2018 Vol. 42 No. 1
2018, 42(1): 1-10.
DOI: 10.7541/2018.001
Abstract:
To investigate the roles of two Cpx component systems in the growth and virulence of Aeromonas hydrophila, we constructed the cpxRA gene cluster mutant Δcpx with the deletion of 57—1879 bp using suicide plasmid pRE112 as the vector. This procedure was based on fusion PCR and gene homologous recombination principles. Through electrophoresis and fluorescence quantitative PCR, the partial deletion of the cpxRA gene cluster in the mutant was confirmed. Then we compared the differences between mutant and wild strains in biological characteristics including growth, biofilm formation, stress tolerance and virulence. The results showed that the mutant had no significant difference with the wild strain in morphology, growth, biofilm formation and virulence. The main differences existed in the response to high osmotic pressure, SDS (Sodium dodecyl sulfate), EDTA (Ethylene Diamine Tetraacetic Acid) and polymyxin B stimulation. This study reveals that the Cpx system of Aeromonas hydrophila is involved in the response to external stimulus factors, and plays a relatively minor role in virulence.
To investigate the roles of two Cpx component systems in the growth and virulence of Aeromonas hydrophila, we constructed the cpxRA gene cluster mutant Δcpx with the deletion of 57—1879 bp using suicide plasmid pRE112 as the vector. This procedure was based on fusion PCR and gene homologous recombination principles. Through electrophoresis and fluorescence quantitative PCR, the partial deletion of the cpxRA gene cluster in the mutant was confirmed. Then we compared the differences between mutant and wild strains in biological characteristics including growth, biofilm formation, stress tolerance and virulence. The results showed that the mutant had no significant difference with the wild strain in morphology, growth, biofilm formation and virulence. The main differences existed in the response to high osmotic pressure, SDS (Sodium dodecyl sulfate), EDTA (Ethylene Diamine Tetraacetic Acid) and polymyxin B stimulation. This study reveals that the Cpx system of Aeromonas hydrophila is involved in the response to external stimulus factors, and plays a relatively minor role in virulence.
2018, 42(1): 11-16.
DOI: 10.7541/2018.002
Abstract:
The bacteria community in the gastrointestinal tract of fish has been the subject of numerous studies. However, most of those researches have focused on the molecular ecology of intestinal microbiota. Few studies pay attention to the bacterial culture, especially to the culture of the anaerobic intestinal bacteria, which leads to poor description in anaerobic autochthonous bacteria of gut. In this study, we investigated the autochthonous microflora of intestinal mucosa in grass carp (Ctenopharyngodon idellus) with the culture dependent method. The bacterial numbers in foregut, midgut and hindgut of the fish were 3.17×104, 1.63×105 and 1.79×108 cfu/g, respectively. A total of 274 bacterial isolations were sequenced and identified as genus Bacteroides, Cetobacterium, Fusobacterium, Aeromonas, Shewanella, Bacilluss, Pantoea and Citrobacter. 9.1% of which were obligate anaerobic bacteria and the others were facultative bacteria. The anaerobic bacteria, Bacteroides paurosaccharolyticus and Bacteroides. Eggerthii, were only found in midgut and hindgut, while Cetobacterium somerae and Fusobacterium varium were only found in hindgut. The facultative bacteria existed in the whole gut, among which Aeromonas hydrophila was dominant. Our results suggest that species and quantities of intestinal bacterial vary with the segments of C. idellus, and hindgut presents higher bacterial abundance and diversity.
The bacteria community in the gastrointestinal tract of fish has been the subject of numerous studies. However, most of those researches have focused on the molecular ecology of intestinal microbiota. Few studies pay attention to the bacterial culture, especially to the culture of the anaerobic intestinal bacteria, which leads to poor description in anaerobic autochthonous bacteria of gut. In this study, we investigated the autochthonous microflora of intestinal mucosa in grass carp (Ctenopharyngodon idellus) with the culture dependent method. The bacterial numbers in foregut, midgut and hindgut of the fish were 3.17×104, 1.63×105 and 1.79×108 cfu/g, respectively. A total of 274 bacterial isolations were sequenced and identified as genus Bacteroides, Cetobacterium, Fusobacterium, Aeromonas, Shewanella, Bacilluss, Pantoea and Citrobacter. 9.1% of which were obligate anaerobic bacteria and the others were facultative bacteria. The anaerobic bacteria, Bacteroides paurosaccharolyticus and Bacteroides. Eggerthii, were only found in midgut and hindgut, while Cetobacterium somerae and Fusobacterium varium were only found in hindgut. The facultative bacteria existed in the whole gut, among which Aeromonas hydrophila was dominant. Our results suggest that species and quantities of intestinal bacterial vary with the segments of C. idellus, and hindgut presents higher bacterial abundance and diversity.
2018, 42(1): 17-25.
DOI: 10.7541/2018.003
Abstract:
A disease called " Shuibiezi” in Eriocheir sinensis was prevailed on Xinghua city, Jiangsu province since 2015, and slowly spread to other main areas of crab rearing in the whole nation. To explore the causes, the etiology by parasites examination, pathogenic bacteria isolation, challenge experiment and electron microscopy observation, and the histopathology by routine paraffin-section technique were conducted with healthy E. sinensis as control groups. Results showed that no pathogenic microorganism was detected by etiology research. Pathological changes with different degrees were observed in gills, muscles and hepatopancreas of diseased crabs, and the main pathological characteristics were gill tissue thickening, enlarged gill cavity, increased number of hemocyte, and marginalized nucleus. Vacuolization of the epithelial cells of the hepatopancreas and transferred vacuoles appeared. With the severity of the conditions, hepatic cells were irregular-arranged, and the number and volume of vacuoles and transferred vacuoles increased, and the number of granular materials in transferred vacuoles increased. With the most severe disease, the hepatic tubles were so ruptured that substances in cells were leaked, and the nucleus of hepatic cells were broken and hepatic cells appeared necrosis. The main lesion characteristics of muscle were muscular fibers appeared to be relaxed and pyknotic of nuclei. Etiology and incidence investigation revealed that the disease was caused by non living agents. Based on the main pathological characteristics and pathogenesis, this disease nominate scientifically as hepatopancreatic necrosis syndrome.
A disease called " Shuibiezi” in Eriocheir sinensis was prevailed on Xinghua city, Jiangsu province since 2015, and slowly spread to other main areas of crab rearing in the whole nation. To explore the causes, the etiology by parasites examination, pathogenic bacteria isolation, challenge experiment and electron microscopy observation, and the histopathology by routine paraffin-section technique were conducted with healthy E. sinensis as control groups. Results showed that no pathogenic microorganism was detected by etiology research. Pathological changes with different degrees were observed in gills, muscles and hepatopancreas of diseased crabs, and the main pathological characteristics were gill tissue thickening, enlarged gill cavity, increased number of hemocyte, and marginalized nucleus. Vacuolization of the epithelial cells of the hepatopancreas and transferred vacuoles appeared. With the severity of the conditions, hepatic cells were irregular-arranged, and the number and volume of vacuoles and transferred vacuoles increased, and the number of granular materials in transferred vacuoles increased. With the most severe disease, the hepatic tubles were so ruptured that substances in cells were leaked, and the nucleus of hepatic cells were broken and hepatic cells appeared necrosis. The main lesion characteristics of muscle were muscular fibers appeared to be relaxed and pyknotic of nuclei. Etiology and incidence investigation revealed that the disease was caused by non living agents. Based on the main pathological characteristics and pathogenesis, this disease nominate scientifically as hepatopancreatic necrosis syndrome.
2018, 42(1): 26-32.
DOI: 10.7541/2018.004
Abstract:
Rotten-skin disease is very common in the artificial culture of the giant spiny frog (Quasipaa spinosa). To screen pathogenic bacteria that cause illness of giant spiny frog, gram stain, morphological observation, physiological, and biochemical identification, and sequence analysis of 16S rDNA were performed and three bacteria (BS1, BS2, and BS3) were identified. The results showed that BS1, BS2, and BS3 are Bacillus cereus. Liver, lung, tongue, and muscle were impaired with degeneration, necrosis, and inflammatory cell infiltration. Moreover, basophilic inclusions were observed in the lung of diseased giant spiny frog. The drug sensitivity test showed that all three pathogenic bacteria were highly sensitive to gentamicin and streptomycin, moderate sensitive to tobramycin, kanamycin and tetracycline, and resistant to ampicillin and ceftazidime. This study explored pathogenesis of rotten-skin disease of giant spiny frog, would provide theoretical basis for prevention and cure of rotten-skin disease of giant spiny frog.
Rotten-skin disease is very common in the artificial culture of the giant spiny frog (Quasipaa spinosa). To screen pathogenic bacteria that cause illness of giant spiny frog, gram stain, morphological observation, physiological, and biochemical identification, and sequence analysis of 16S rDNA were performed and three bacteria (BS1, BS2, and BS3) were identified. The results showed that BS1, BS2, and BS3 are Bacillus cereus. Liver, lung, tongue, and muscle were impaired with degeneration, necrosis, and inflammatory cell infiltration. Moreover, basophilic inclusions were observed in the lung of diseased giant spiny frog. The drug sensitivity test showed that all three pathogenic bacteria were highly sensitive to gentamicin and streptomycin, moderate sensitive to tobramycin, kanamycin and tetracycline, and resistant to ampicillin and ceftazidime. This study explored pathogenesis of rotten-skin disease of giant spiny frog, would provide theoretical basis for prevention and cure of rotten-skin disease of giant spiny frog.
Abstract:
To identify Ligula intestinalis pleroceroid parasitizing in the abdominal cavity of Gymnocypris przewalskii and analyze its phylogenic status from Qinghai Lake, China, polymerase chain reaction (PCR) of 18S ribosomal RNA gene, COⅠand COB gene was carried out. Their sequences homologies with other tapeworm species were analyzed and the phylogenetic relationships were inferred. The results showed that the noodle-like parasite was identified as L. intestinalis, and that its 18S rRNA gene homogeneity was 100.00% with AF254121 (China), and COⅠand COB gene homogeneities were 99.49% and 93.32% with AF153910 (China) and JQ279109 (Algeria), respectively. Furthermore, the phylogenetic trees based on the 18S rRNA, COⅠand COB gene sequences indicated that the collected tapeworm was in the same branch with L. intestinalis, which are close to the isolated species from China. The phylogenetic relationship between the identified L. intestinalis and other tapeworm species was elucidated.
To identify Ligula intestinalis pleroceroid parasitizing in the abdominal cavity of Gymnocypris przewalskii and analyze its phylogenic status from Qinghai Lake, China, polymerase chain reaction (PCR) of 18S ribosomal RNA gene, COⅠand COB gene was carried out. Their sequences homologies with other tapeworm species were analyzed and the phylogenetic relationships were inferred. The results showed that the noodle-like parasite was identified as L. intestinalis, and that its 18S rRNA gene homogeneity was 100.00% with AF254121 (China), and COⅠand COB gene homogeneities were 99.49% and 93.32% with AF153910 (China) and JQ279109 (Algeria), respectively. Furthermore, the phylogenetic trees based on the 18S rRNA, COⅠand COB gene sequences indicated that the collected tapeworm was in the same branch with L. intestinalis, which are close to the isolated species from China. The phylogenetic relationship between the identified L. intestinalis and other tapeworm species was elucidated.
2018, 42(1): 39-46.
DOI: 10.7541/2018.006
Abstract:
The goal of this study was to prepare the alginate-chitosan microcapsules containing the Srr-protein of Streptococcus iniae, and to determine its immune effect in channel catfish by oral route. The alginate-chitosan-Srr-protein microcapsules were prepared by an emulsification method, and the encapsulation efficiency, drug-loaded rate, and immunogenicity integrity were tested. Healthy fish were divided into 4 groups, named Srr group, Srr-microcapsules group, empty-microcapsules group, and control group to immune, respectively. The serum antibody level was detected by an indirect ELISA method, and serum non-specific indexes were detected by reagent kits. 4 weeks after the immunization, the relative percent survivals (RPSs) of each group were calculated by challenging the fish with S. iniae, and the mRNA levels of immune related genes were analyzed by real-time PCR. The alginate-chitosan-Srr-protein microcapsules showed round or oval in shapes, with a mean diameter of 4.26±1.13 μm, an encapsulation efficiency of 92.38%, and a drug-loaded rate of 19.41%. Western-blot indicated a good immunogenicity of the microcapsules. The peak of antibody titer appeared at the 4th week after the immunization, among which, antibody titer in the Srr-microcapsules group was the highest. The serum total protein, T-SOD and lysozyme activity of Srr-microcapsules group were obviously higher than those of the other groups. The relative percentage of survival in Srr-microcapsules group was 60%. The results of real-time PCR presented that mRNA levels of immune related genes in kidneys and spleens from the Srr group increased more notably than those in the other groups during the 24h to 48h post injection. In conclusion, the alginate-chitosan-Srr-protein microcapsules vaccine was able to protect channel catfish from S. iniae infection.
The goal of this study was to prepare the alginate-chitosan microcapsules containing the Srr-protein of Streptococcus iniae, and to determine its immune effect in channel catfish by oral route. The alginate-chitosan-Srr-protein microcapsules were prepared by an emulsification method, and the encapsulation efficiency, drug-loaded rate, and immunogenicity integrity were tested. Healthy fish were divided into 4 groups, named Srr group, Srr-microcapsules group, empty-microcapsules group, and control group to immune, respectively. The serum antibody level was detected by an indirect ELISA method, and serum non-specific indexes were detected by reagent kits. 4 weeks after the immunization, the relative percent survivals (RPSs) of each group were calculated by challenging the fish with S. iniae, and the mRNA levels of immune related genes were analyzed by real-time PCR. The alginate-chitosan-Srr-protein microcapsules showed round or oval in shapes, with a mean diameter of 4.26±1.13 μm, an encapsulation efficiency of 92.38%, and a drug-loaded rate of 19.41%. Western-blot indicated a good immunogenicity of the microcapsules. The peak of antibody titer appeared at the 4th week after the immunization, among which, antibody titer in the Srr-microcapsules group was the highest. The serum total protein, T-SOD and lysozyme activity of Srr-microcapsules group were obviously higher than those of the other groups. The relative percentage of survival in Srr-microcapsules group was 60%. The results of real-time PCR presented that mRNA levels of immune related genes in kidneys and spleens from the Srr group increased more notably than those in the other groups during the 24h to 48h post injection. In conclusion, the alginate-chitosan-Srr-protein microcapsules vaccine was able to protect channel catfish from S. iniae infection.
2018, 42(1): 47-56.
DOI: 10.7541/2018.007
Abstract:
This study investigated the effects of sulfadiazine exposure at three different concentrations (1 μg/L, 100 μg/L and 10 mg/L) for 28d on histopathology of the liver, kidney, gill, muscle and gut of Carassius auratus gibelio by semi-static test method. The results showed that different pathological changes occurred on the liver, kidney, gill and muscle of Carassius auratus gibelio under different concentrations of sulfadiazine stress, which included the congestion, vacuolation, karyopyknosis, necrosis of liver cell, the vacuolar degeneration of epithelial cells, necrocytosis in glomerulus and congestion in renal interstitium, the edema of epithelial cell in gill lamellae, hyperplasia and disappearance of gill lamellae, the exfoliation of microvilli, thicker submucosa and vacuoles degeneration and necrosis of muscularis, the widened gap, disorder and fragmentation of myofiber. Among all the tissues, liver, gill and kidney presented more serious pathological lesions than other two tissues and damage of tissues was inhibited obviously in a time and dose dependant manner. Thus, this study can provide theoretical guidance for the rational use of sulfonamides drugs in the aquaculture process.
This study investigated the effects of sulfadiazine exposure at three different concentrations (1 μg/L, 100 μg/L and 10 mg/L) for 28d on histopathology of the liver, kidney, gill, muscle and gut of Carassius auratus gibelio by semi-static test method. The results showed that different pathological changes occurred on the liver, kidney, gill and muscle of Carassius auratus gibelio under different concentrations of sulfadiazine stress, which included the congestion, vacuolation, karyopyknosis, necrosis of liver cell, the vacuolar degeneration of epithelial cells, necrocytosis in glomerulus and congestion in renal interstitium, the edema of epithelial cell in gill lamellae, hyperplasia and disappearance of gill lamellae, the exfoliation of microvilli, thicker submucosa and vacuoles degeneration and necrosis of muscularis, the widened gap, disorder and fragmentation of myofiber. Among all the tissues, liver, gill and kidney presented more serious pathological lesions than other two tissues and damage of tissues was inhibited obviously in a time and dose dependant manner. Thus, this study can provide theoretical guidance for the rational use of sulfonamides drugs in the aquaculture process.
2018, 42(1): 57-67.
DOI: 10.7541/2018.008
Abstract:
Transcriptome analysis of yellow catfish (Pelteobagrus fulvidraco) by RNA-seq method extracting gastrointestinal mucosa Total RNA was studied in this paper. The fish were fed with oxidized fish oil and fish oil respectively for 7d. Differential expression of genes related to melanin synthesis, melanosomes movement, melanocyte stimulating hormone-α pathway and three signal pathways controlling melanocyte differentiation were analyzed. The results showed that there were metabolic networks of melanocyte differentiation and development, melanin synthesis and regulation in the gastrointestinal mucosa. The genetic information of key enzymes and protein of melanin synthesis were introduced with plotting metabolic networks graph. The melanin content was deficient because of the genes expression level were significantly down-regulation related to controlling melanin synthesis after fed with oxidized fish oil. While melanocyte differentiation and development were improved because of the genes expression level were significantly up-regulation related to melanocyte stimulating hormone-α pathway (α-MSH). In the same time, genes expression level of WNT/β-catenin, EDN3 / EDNRB and KIT/KITL signal pathways were different. In conclusion, feeding oxidized fish oil affected melanocyte differentiation and development and reduced melanocyte number which benefited to maturity in yellow catfish. Insufficient melanin biosynthesis also led to body color variation of yellow catfish.
Transcriptome analysis of yellow catfish (Pelteobagrus fulvidraco) by RNA-seq method extracting gastrointestinal mucosa Total RNA was studied in this paper. The fish were fed with oxidized fish oil and fish oil respectively for 7d. Differential expression of genes related to melanin synthesis, melanosomes movement, melanocyte stimulating hormone-α pathway and three signal pathways controlling melanocyte differentiation were analyzed. The results showed that there were metabolic networks of melanocyte differentiation and development, melanin synthesis and regulation in the gastrointestinal mucosa. The genetic information of key enzymes and protein of melanin synthesis were introduced with plotting metabolic networks graph. The melanin content was deficient because of the genes expression level were significantly down-regulation related to controlling melanin synthesis after fed with oxidized fish oil. While melanocyte differentiation and development were improved because of the genes expression level were significantly up-regulation related to melanocyte stimulating hormone-α pathway (α-MSH). In the same time, genes expression level of WNT/β-catenin, EDN3 / EDNRB and KIT/KITL signal pathways were different. In conclusion, feeding oxidized fish oil affected melanocyte differentiation and development and reduced melanocyte number which benefited to maturity in yellow catfish. Insufficient melanin biosynthesis also led to body color variation of yellow catfish.
Abstract:
Trypsin is a serine protease that plays a major role in protein digestion. It is synthesized and secreted by pancreas as a prepro enzyme, trypsinogen. In the present study, a full-length cDNA of goldfish trypsinogen (gfTryp) was successfully cloned from the hepatopancreas by rapid amplification of cDNA ends technique. The obtained gfTryp cDNA was 864 bp long with a 21 bp 5′-untranslated region (UTR), a 114 bp 3′-UTR containing the consensus polyadenylation signal AATAAA, and a 729 bp open reading frame encoding a protein of 242 amino acid residues. Sequence alignment showed that the gfTryp possessed all the characteristic features of trypsin family, suggesting its conserved function in protein digestion. Its mRNA expression was observed in all tissues examined, and the relatively higher levels were detected in hepatopancreas, intestine and fat. Hepatopancreatic gfTryp mRNA level decreased significantly after fasting for one week. Further periprandial expression analysis showed that gfTryp mRNA expression level in hepatopancreas dramatically up-regulated after meal. Hepatopancreatic gfTryp mRNA expression level increased significantly with 0.5 and 5 μg/mL cadmium (3.2 and 4.7 fold, respectively), and decreased with cadmium concentration up to 10 μg/mL. Strikingly, H2O2 exposure significantly decreased gfTryp mRNA expression in hepatopancreas at 3h, 6h, 12h and 24h. Our study provides the evidence that nutritional status, cadmium and oxidative stress can regulate the trypsinogen expression at the transcript level, and sheds new light on the physiological expression of trypsinogen in fish.
Trypsin is a serine protease that plays a major role in protein digestion. It is synthesized and secreted by pancreas as a prepro enzyme, trypsinogen. In the present study, a full-length cDNA of goldfish trypsinogen (gfTryp) was successfully cloned from the hepatopancreas by rapid amplification of cDNA ends technique. The obtained gfTryp cDNA was 864 bp long with a 21 bp 5′-untranslated region (UTR), a 114 bp 3′-UTR containing the consensus polyadenylation signal AATAAA, and a 729 bp open reading frame encoding a protein of 242 amino acid residues. Sequence alignment showed that the gfTryp possessed all the characteristic features of trypsin family, suggesting its conserved function in protein digestion. Its mRNA expression was observed in all tissues examined, and the relatively higher levels were detected in hepatopancreas, intestine and fat. Hepatopancreatic gfTryp mRNA level decreased significantly after fasting for one week. Further periprandial expression analysis showed that gfTryp mRNA expression level in hepatopancreas dramatically up-regulated after meal. Hepatopancreatic gfTryp mRNA expression level increased significantly with 0.5 and 5 μg/mL cadmium (3.2 and 4.7 fold, respectively), and decreased with cadmium concentration up to 10 μg/mL. Strikingly, H2O2 exposure significantly decreased gfTryp mRNA expression in hepatopancreas at 3h, 6h, 12h and 24h. Our study provides the evidence that nutritional status, cadmium and oxidative stress can regulate the trypsinogen expression at the transcript level, and sheds new light on the physiological expression of trypsinogen in fish.
2018, 42(1): 77-85.
DOI: 10.7541/2018.010
Abstract:
Ikaros is a kind of transcription factor with zinc finger structure that is essential to the development of lymphocyte. In order to reveal the structure characteristic of Ikaros gene and the immune modulatory mechanisms of Ikaros gene on disease resistant, the cDNA of Ikaros were obtained from Oreochromis niloticus with RT-PCR and RACE methods, and the genomic DNA of Ikaros were obtained by using PCR and Genome Walking technique in this study. Quantitative real-time PCR was used for analyzing the organization distribution and the response of Ikaros to Streptococcus agalactiae infection. The genomic DNA is 20545 bp with 7 introns and 8 exons encoding 6 kinds of mRNA splicing isoform via alternative splicing. The deduced amino acid sequences of the six splicing isoforms with zinc finger domain have high homology (70.6%—93.7%) in other teleost fish. The Ikaros gene expressed in all tested tissues, which strongly expressed in blood, and moderately expressed in thymus, spleen and head kidney. After challenged with pathogenic bacteria Streptococcus agalactiae, the Ikaros gene expression levels rose in blood, thymus, spleen and head kidney, and then reached to the peak after 48 hours. The results suggested that Ikaros gene participated in the immune response of Nile tilapia against Streptococcus agalactiae infection. This research laid a foundation for further study on the disease resistant mechanism of Ikaros gene.
Ikaros is a kind of transcription factor with zinc finger structure that is essential to the development of lymphocyte. In order to reveal the structure characteristic of Ikaros gene and the immune modulatory mechanisms of Ikaros gene on disease resistant, the cDNA of Ikaros were obtained from Oreochromis niloticus with RT-PCR and RACE methods, and the genomic DNA of Ikaros were obtained by using PCR and Genome Walking technique in this study. Quantitative real-time PCR was used for analyzing the organization distribution and the response of Ikaros to Streptococcus agalactiae infection. The genomic DNA is 20545 bp with 7 introns and 8 exons encoding 6 kinds of mRNA splicing isoform via alternative splicing. The deduced amino acid sequences of the six splicing isoforms with zinc finger domain have high homology (70.6%—93.7%) in other teleost fish. The Ikaros gene expressed in all tested tissues, which strongly expressed in blood, and moderately expressed in thymus, spleen and head kidney. After challenged with pathogenic bacteria Streptococcus agalactiae, the Ikaros gene expression levels rose in blood, thymus, spleen and head kidney, and then reached to the peak after 48 hours. The results suggested that Ikaros gene participated in the immune response of Nile tilapia against Streptococcus agalactiae infection. This research laid a foundation for further study on the disease resistant mechanism of Ikaros gene.
2018, 42(1): 86-93.
DOI: 10.7541/2018.011
Abstract:
This study cloned the cDNA of hemocyanin subunit from Exopalaemon carinicauda (named EcHcL) by rapid amplification of cDNA ends (RACE). The EcHcL cDNA was 2192 bp in length including a 2034 bp open reading frame (ORF) that encoded a 667 amino acids polypeptide with a signal peptide sequence (1—21 amino acid residues). The predicted molecular weight of the mature peptide was 78.5 kD. The homology analysis revealed that the amino acid sequence of EcHcL was highly conserved with other arthropod. The homology similarities of EcHcL amino acids with Macrobarchium nipponense hemocyanin and Litopenaeus vannamei amino acid sequence were 87% and 73%, respectively. The similarity of the M domain of the amino acid sequence between EcHcL and other shrimp was about 90%. EcHcL was detected in all tested tissues including gill, ovary, hepatopancreas, heart, intestine, muscle, stomach, abdominal ganglion, eyestalk and haemocytes with the highest expression in hepatopancreas. EcHcL was induced distinctly in the hepatopancreas and haemocytes of shrimp by Staphylococcus aureus, Vibrio parahaemolyticus and white spot syndrome virus (WSSV). The results suggest that the different temporal expression pattern of EcHcL might play an important role in shrimp immune system.
This study cloned the cDNA of hemocyanin subunit from Exopalaemon carinicauda (named EcHcL) by rapid amplification of cDNA ends (RACE). The EcHcL cDNA was 2192 bp in length including a 2034 bp open reading frame (ORF) that encoded a 667 amino acids polypeptide with a signal peptide sequence (1—21 amino acid residues). The predicted molecular weight of the mature peptide was 78.5 kD. The homology analysis revealed that the amino acid sequence of EcHcL was highly conserved with other arthropod. The homology similarities of EcHcL amino acids with Macrobarchium nipponense hemocyanin and Litopenaeus vannamei amino acid sequence were 87% and 73%, respectively. The similarity of the M domain of the amino acid sequence between EcHcL and other shrimp was about 90%. EcHcL was detected in all tested tissues including gill, ovary, hepatopancreas, heart, intestine, muscle, stomach, abdominal ganglion, eyestalk and haemocytes with the highest expression in hepatopancreas. EcHcL was induced distinctly in the hepatopancreas and haemocytes of shrimp by Staphylococcus aureus, Vibrio parahaemolyticus and white spot syndrome virus (WSSV). The results suggest that the different temporal expression pattern of EcHcL might play an important role in shrimp immune system.
2018, 42(1): 94-98.
DOI: 10.7541/2018.012
Abstract:
The Chinese sturgeon (Acipenser sinensis), an endangered and national protected species, is an important resource for sturgeon aquaculture industry. This study cloned the full-length cDNA of the gonadotropin-releasing hormone receptor (GnRH-R) from pituitary cDNA library of a 24 years old female Chinese sturgeon using rapid amplification of cDNA ends (RACE). The nucleotide sequences of AsGnRH-R is 1530 bp in length, containing a 478 bp 5′-untranslated region (UTR), a 473 bp 3′-UTR, and a 579 bp open reading frame (ORF) with a mature peptide of 192 amino acids encompassing 5 putative N-glycosylation sites. Multiple sequence alignment and phylogenetic analysis of the deduced amino acid sequence of AsGnRH-R indicated that the most similar ortholog was red sea bream (Pagrus major) (76%), and that the least similar ortholog was Callorhinchus milii (39%). Real-time quantitative PCR analysis indicated that the AsGnRH-R was expressed in tissues including liver, spleen, kidney, testis, muscle, intestine, and brain with the highest level in the testis.
The Chinese sturgeon (Acipenser sinensis), an endangered and national protected species, is an important resource for sturgeon aquaculture industry. This study cloned the full-length cDNA of the gonadotropin-releasing hormone receptor (GnRH-R) from pituitary cDNA library of a 24 years old female Chinese sturgeon using rapid amplification of cDNA ends (RACE). The nucleotide sequences of AsGnRH-R is 1530 bp in length, containing a 478 bp 5′-untranslated region (UTR), a 473 bp 3′-UTR, and a 579 bp open reading frame (ORF) with a mature peptide of 192 amino acids encompassing 5 putative N-glycosylation sites. Multiple sequence alignment and phylogenetic analysis of the deduced amino acid sequence of AsGnRH-R indicated that the most similar ortholog was red sea bream (Pagrus major) (76%), and that the least similar ortholog was Callorhinchus milii (39%). Real-time quantitative PCR analysis indicated that the AsGnRH-R was expressed in tissues including liver, spleen, kidney, testis, muscle, intestine, and brain with the highest level in the testis.
2018, 42(1): 99-105.
DOI: 10.7541/2018.013
Abstract:
In order to determine the species composition of genus Sillago, this study measured 411 Sillago individuals, which were collected from the coastal waters of Zhoushan and Wenzhou, Zhejiang Province. The mitochondrial cytochrome c oxidase subunit 1 (CO I) gene sequences were used for genetic diversity and molecular phylogenetic analysis. The results showed that only Sillago japonica and Sillago sinica distributed in the coastal waters of Zhejiang. These two species were different in morphology, especially in the shape of swim bladder. We obtained 600 bp CO I sequences, and the GC contents for S. japonica and S. sinica in all position were 46.6% and 49.9%, respectively. The mean genetic distances by Kimura-2-parameter model within S. japonica and S. sinica were 0.002 and 0.000, respectively; and the mean genetic distance between S. japonica and S. sinica was 0.211. The NJ tree revealed that all 7 Sillago species formed monophyletic groups. This study classified the Sillago species in the coastal waters of Zhejiang, and reinforced the validity of DNA barcoding on classification of Sillago species based on CO Ⅰ gene.
In order to determine the species composition of genus Sillago, this study measured 411 Sillago individuals, which were collected from the coastal waters of Zhoushan and Wenzhou, Zhejiang Province. The mitochondrial cytochrome c oxidase subunit 1 (CO I) gene sequences were used for genetic diversity and molecular phylogenetic analysis. The results showed that only Sillago japonica and Sillago sinica distributed in the coastal waters of Zhejiang. These two species were different in morphology, especially in the shape of swim bladder. We obtained 600 bp CO I sequences, and the GC contents for S. japonica and S. sinica in all position were 46.6% and 49.9%, respectively. The mean genetic distances by Kimura-2-parameter model within S. japonica and S. sinica were 0.002 and 0.000, respectively; and the mean genetic distance between S. japonica and S. sinica was 0.211. The NJ tree revealed that all 7 Sillago species formed monophyletic groups. This study classified the Sillago species in the coastal waters of Zhejiang, and reinforced the validity of DNA barcoding on classification of Sillago species based on CO Ⅰ gene.
Abstract:
This study investigated the genetic diversity and population demographic history of Hemiculterella sauvagei based on the sequence analysis of mtDNA (Cyt b) of 168 individuals from five geographical populations including Shuiliao, Maotai, Erhe, Taiping and Chishui. After alignment, 1137 bp sequence including 42 variable sites, 13 singleton sites, 29 parsimony informative sites and 38 haplotypes were acquired and revealed, among which Hap1, Hap2 and Hap6 were shared by all populations. The haplotype diversity (Hd) and nucleotide diversity (Pi) were 0.895±0.012 and 0.00487±0.00695, respectively. Analysis of molecular variance (AMOVA) indicated that genetic variations between different geographical populations in the Chishui River were mainly within group. Genetic differentiation index (Fst) indicated high genetic differentiation between Chishui and Maotai, Erhe and Shuiliao population as well as medium genetic differentiation between Chishui and Taiping population. The overall mean genetic distances among five populations were between 0.004—0.006. Tajima’s D and Fu’s Fs neutral tests showed that historical population expansion observed in Taiping, Shuiliao and Chishui population but not in Maotai and Erhe. The population expansion of Shuiliao, Taiping and Chishui appeared in 0.43 Mya, 0.40 Mya and 0.37 Mya, respectively.
This study investigated the genetic diversity and population demographic history of Hemiculterella sauvagei based on the sequence analysis of mtDNA (Cyt b) of 168 individuals from five geographical populations including Shuiliao, Maotai, Erhe, Taiping and Chishui. After alignment, 1137 bp sequence including 42 variable sites, 13 singleton sites, 29 parsimony informative sites and 38 haplotypes were acquired and revealed, among which Hap1, Hap2 and Hap6 were shared by all populations. The haplotype diversity (Hd) and nucleotide diversity (Pi) were 0.895±0.012 and 0.00487±0.00695, respectively. Analysis of molecular variance (AMOVA) indicated that genetic variations between different geographical populations in the Chishui River were mainly within group. Genetic differentiation index (Fst) indicated high genetic differentiation between Chishui and Maotai, Erhe and Shuiliao population as well as medium genetic differentiation between Chishui and Taiping population. The overall mean genetic distances among five populations were between 0.004—0.006. Tajima’s D and Fu’s Fs neutral tests showed that historical population expansion observed in Taiping, Shuiliao and Chishui population but not in Maotai and Erhe. The population expansion of Shuiliao, Taiping and Chishui appeared in 0.43 Mya, 0.40 Mya and 0.37 Mya, respectively.
2018, 42(1): 114-122.
DOI: 10.7541/2018.015
Abstract:
Baits is an important factor for fish growth and development. In order to find a proper bait for the larvae and juvenile Gobiocypris rarus, we divided newly hatched larvae into three groups randomly: live bait group, artificial diet group and food conversion group. Each group has three parallel samples. The fish of each group were fed since 3 dah (day after hatching) with the three different diets mentioned before, and the growth and survival rates of the larvae and juveniles were measured on 10, 15, 20, 25, 30, 35 dah. We also studied the structure and the function of the digestive tract by histological methods, and measured the digestive enzyme activities on 35 dah. Results showed that: (1) the live bait group had the highest survival rate on 35 dah; (2) from 15 dah, fish in the live bait group showed the best growing performance, and kept that trend until 35 dah; (3) muscle layer thickness and mucous cell numbers of the entire digestive tract in the live bait group were the highest, which suggested a more developed digestive tract and thus a better capacity in digestion and absorption; (4) the maximum activity of trypsase was observed in the larvae and juvenile group fed with baits. All those results mentioned above indicated that: compared with artificial diet and food conversion, live baits were the best choice for the growth and development of larvae and juvenile Gobiocypris rarus. We suggested that live baits should be taken to feed larvae and juvenile Gobiocypris rarus in the process of standardized cultivation.
Baits is an important factor for fish growth and development. In order to find a proper bait for the larvae and juvenile Gobiocypris rarus, we divided newly hatched larvae into three groups randomly: live bait group, artificial diet group and food conversion group. Each group has three parallel samples. The fish of each group were fed since 3 dah (day after hatching) with the three different diets mentioned before, and the growth and survival rates of the larvae and juveniles were measured on 10, 15, 20, 25, 30, 35 dah. We also studied the structure and the function of the digestive tract by histological methods, and measured the digestive enzyme activities on 35 dah. Results showed that: (1) the live bait group had the highest survival rate on 35 dah; (2) from 15 dah, fish in the live bait group showed the best growing performance, and kept that trend until 35 dah; (3) muscle layer thickness and mucous cell numbers of the entire digestive tract in the live bait group were the highest, which suggested a more developed digestive tract and thus a better capacity in digestion and absorption; (4) the maximum activity of trypsase was observed in the larvae and juvenile group fed with baits. All those results mentioned above indicated that: compared with artificial diet and food conversion, live baits were the best choice for the growth and development of larvae and juvenile Gobiocypris rarus. We suggested that live baits should be taken to feed larvae and juvenile Gobiocypris rarus in the process of standardized cultivation.
2018, 42(1): 123-130.
DOI: 10.7541/2018.016
Abstract:
In order to evaluate the effect of DHA on the growth and lipid metabolism of common carp (Cyprinus carpio L.), using casein, dextrin, cellulose, soybean oil and fish compound premix as the raw feed two diets with lipid level of 6% and 12% were prepared for Cyprinus carpio L. 3% soybean oil in the two diets was replaced by 50% DHA to produce four diets, which included 6L group, 6L-DHA group, 12L group and 12L-DHA group. A total of 360 common carps (14.81±0.13 g) were randomly divided into four groups (triplicate per group), and fed with four diets, respectively, for 74 days. After then, growth performance, biological parameters, body composition, serum biochemical indicators and tissue morphological were determined. The results showed that compared with 6L group, the feed efficiency, absolute growth rate and relative growth rate decreased significantly in 6L-DHA group (P<0.05). The absolute growth rate was significantly lower in 12L-DHA group than that of 12L group (P<0.05). The intraperiotenal fat index and adipocyte area of intraperiotenal fat tissue were significantly lower in 6L-DHA group than that in 6L group (P<0.05). The crude lipid content in the muscle decreased significantly in DHA diet (P<0.05). However, the content of serum total cholesterol increased significantly in DHA diet. Results showed that the growth and health status of common carp were compromised by adding DHA in lipid diets, which was probably caused by the high level of DHA in diet and it would be avoided by increasing dietary lipid level.
In order to evaluate the effect of DHA on the growth and lipid metabolism of common carp (Cyprinus carpio L.), using casein, dextrin, cellulose, soybean oil and fish compound premix as the raw feed two diets with lipid level of 6% and 12% were prepared for Cyprinus carpio L. 3% soybean oil in the two diets was replaced by 50% DHA to produce four diets, which included 6L group, 6L-DHA group, 12L group and 12L-DHA group. A total of 360 common carps (14.81±0.13 g) were randomly divided into four groups (triplicate per group), and fed with four diets, respectively, for 74 days. After then, growth performance, biological parameters, body composition, serum biochemical indicators and tissue morphological were determined. The results showed that compared with 6L group, the feed efficiency, absolute growth rate and relative growth rate decreased significantly in 6L-DHA group (P<0.05). The absolute growth rate was significantly lower in 12L-DHA group than that of 12L group (P<0.05). The intraperiotenal fat index and adipocyte area of intraperiotenal fat tissue were significantly lower in 6L-DHA group than that in 6L group (P<0.05). The crude lipid content in the muscle decreased significantly in DHA diet (P<0.05). However, the content of serum total cholesterol increased significantly in DHA diet. Results showed that the growth and health status of common carp were compromised by adding DHA in lipid diets, which was probably caused by the high level of DHA in diet and it would be avoided by increasing dietary lipid level.
2018, 42(1): 131-137.
DOI: 10.7541/2018.017
Abstract:
Intermuscular bones, existing only in teleosts among advanced vertebrates, are segmental, serially homologous ossifications in the myosepta. However, there is limited information on the development and ossification of intermuscular bones. In the present study, the morphological development of intermuscular bone in rice eel (Monopterus albus) and weather loach (Misgurnus anguillicaudatus) was investigated using bone clearing and staining method. Study of these two species may imply the evolutionary ossification in teleost due to their different evolutionary status and different swimming modes. The results showed that in M. albus, a typical anguilliform swimmer and belonging to Synbranchidae of Synbgranchiformes, initial intermuscular bones (epicentrals) were ossified at anterior part at 30 days post hatching (dph) with the body length (BL) of 40 mm. Then intermuscular bones were ossified from the anterior to the posterior part. At 55 dph (BL 100 mm), all the intermuscular bones were basically appeared with all type " I” epicentral bones. However, in M. anguillicaudatus, carangiform swimmer and belonging to Cobitidae of Cypriniformes, initial intermuscular bones including epineurals and epipleural bones were ossified at posterior part at 27 dph (BL 17 mm). Then intermuscular bones were ossified from the posterior to the anterior part. At 40 dph (BL 35 mm), all the intermuscular bones were basically appeared with the types of " I”, " Y” and " 卜”. Moreover, through the use of osteoblast specific transcription factor (osterix) green fluorescent protein transgenic (osterix GFP) zebrafish (Danio rerio), the process of development and ossification of intermuscular bones were observed in vivo and the results showed that the intermuscular bones were ossified from the posterior to the anterior parts in D. rerio. The results from this study indicated that the ossification of intermuscular bones might be related to fish swimming mode, and their morphological polymorphism may be correlated with fish swimming mode and body type. However, whether the ossification of intermuscular bones has relation with fish phylogenetic evolution needs to be further explored.
Intermuscular bones, existing only in teleosts among advanced vertebrates, are segmental, serially homologous ossifications in the myosepta. However, there is limited information on the development and ossification of intermuscular bones. In the present study, the morphological development of intermuscular bone in rice eel (Monopterus albus) and weather loach (Misgurnus anguillicaudatus) was investigated using bone clearing and staining method. Study of these two species may imply the evolutionary ossification in teleost due to their different evolutionary status and different swimming modes. The results showed that in M. albus, a typical anguilliform swimmer and belonging to Synbranchidae of Synbgranchiformes, initial intermuscular bones (epicentrals) were ossified at anterior part at 30 days post hatching (dph) with the body length (BL) of 40 mm. Then intermuscular bones were ossified from the anterior to the posterior part. At 55 dph (BL 100 mm), all the intermuscular bones were basically appeared with all type " I” epicentral bones. However, in M. anguillicaudatus, carangiform swimmer and belonging to Cobitidae of Cypriniformes, initial intermuscular bones including epineurals and epipleural bones were ossified at posterior part at 27 dph (BL 17 mm). Then intermuscular bones were ossified from the posterior to the anterior part. At 40 dph (BL 35 mm), all the intermuscular bones were basically appeared with the types of " I”, " Y” and " 卜”. Moreover, through the use of osteoblast specific transcription factor (osterix) green fluorescent protein transgenic (osterix GFP) zebrafish (Danio rerio), the process of development and ossification of intermuscular bones were observed in vivo and the results showed that the intermuscular bones were ossified from the posterior to the anterior parts in D. rerio. The results from this study indicated that the ossification of intermuscular bones might be related to fish swimming mode, and their morphological polymorphism may be correlated with fish swimming mode and body type. However, whether the ossification of intermuscular bones has relation with fish phylogenetic evolution needs to be further explored.
2018, 42(1): 138-147.
DOI: 10.7541/2018.018
Abstract:
To study age and growth of Creteuchiloglanis macropterus, 230 specimens were collected from the Nu River, Binlang River and Longchuan River from November 2013 to September 2014. Simplified decalcified histological sections of pectoral fin spines were used to estimate the age. Reader agreement rate of ages between pectoral fin spines and vertebra was 86.36%. Pectoral fin spines could be used for estimating the age efficiently. There were nine age groups of collected samples, and most individuals were 1—3 year-old accounting for about 65% of total samples. The relationship between the radius of pectoral fin spines (RC) and total length (L) was L=2.0787·RC0.6273 (R2=0.8866, n=180). There was no significant difference between measured body length and back-calculated body length at each age group (χ2=0.776, df=8, P=0.999). Meanwhile, the relationship between total length (L) and body weight (W) showed no significant difference between females and males, and it expressed as W=1E–4L2.4807 (R2=0.8189, n=180). Von Bertalanffy growth function was Lt=377.015·[1–e–0.0491(t+4.0195)], Wt=246.134·[1–e–0.0491(t+4.0195)]2.4807. In addition, the age at the inflection point of body weight growth was 14.48 years, in which total length and body weight were 225.00 mm and 68.40 g, respectively. C. macropterus was allometric growth and individual miniaturization. Its resources were heavy damaged. We should take action to strictly ban unreasonable catching in the future and strengthen scientific research on C. macropterus to preserve the resources.
To study age and growth of Creteuchiloglanis macropterus, 230 specimens were collected from the Nu River, Binlang River and Longchuan River from November 2013 to September 2014. Simplified decalcified histological sections of pectoral fin spines were used to estimate the age. Reader agreement rate of ages between pectoral fin spines and vertebra was 86.36%. Pectoral fin spines could be used for estimating the age efficiently. There were nine age groups of collected samples, and most individuals were 1—3 year-old accounting for about 65% of total samples. The relationship between the radius of pectoral fin spines (RC) and total length (L) was L=2.0787·RC0.6273 (R2=0.8866, n=180). There was no significant difference between measured body length and back-calculated body length at each age group (χ2=0.776, df=8, P=0.999). Meanwhile, the relationship between total length (L) and body weight (W) showed no significant difference between females and males, and it expressed as W=1E–4L2.4807 (R2=0.8189, n=180). Von Bertalanffy growth function was Lt=377.015·[1–e–0.0491(t+4.0195)], Wt=246.134·[1–e–0.0491(t+4.0195)]2.4807. In addition, the age at the inflection point of body weight growth was 14.48 years, in which total length and body weight were 225.00 mm and 68.40 g, respectively. C. macropterus was allometric growth and individual miniaturization. Its resources were heavy damaged. We should take action to strictly ban unreasonable catching in the future and strengthen scientific research on C. macropterus to preserve the resources.
2018, 42(1): 148-154.
DOI: 10.7541/2018.019
Abstract:
Fish behavior change can be used as a sensitive indicator to identify sudden environmental pollution. This study conducted a quantitative analysis on a respiratory metabolism, swim behavior and copper content in tissues of silver carp under different copper concentration (0, 1, 2, 3, 4 mg/L). The results indicated that the exercise duration and the respiratory frequency of juvenile silver carp were significantly affected by the copper concentration. As the copper concentration increased, the exercise duration declined significantly. When the copper concentration was 4.00 mg/L, the exercise duration decreased by 72.41% compared with the control group. The increased copper concentration reduced the average speed, average acceleration and total distance in 5-min exercise duration. The minimum average speed, minimum average positive acceleration and the minimum average negative acceleration were 29.50 mm/s, 45.18 mm/s2 and 42.64 mm/s2, respectively. Positive acceleration was higher than the negative acceleration. The copper content in tissues of juvenile silver carp was: liver>gill>muscle, but without significant difference among tissues. The study provides basic data and theoretical basis of water quality by monitoring fish behaviors changes to give early warning and comprehensive evaluation on the toxicity level.
Fish behavior change can be used as a sensitive indicator to identify sudden environmental pollution. This study conducted a quantitative analysis on a respiratory metabolism, swim behavior and copper content in tissues of silver carp under different copper concentration (0, 1, 2, 3, 4 mg/L). The results indicated that the exercise duration and the respiratory frequency of juvenile silver carp were significantly affected by the copper concentration. As the copper concentration increased, the exercise duration declined significantly. When the copper concentration was 4.00 mg/L, the exercise duration decreased by 72.41% compared with the control group. The increased copper concentration reduced the average speed, average acceleration and total distance in 5-min exercise duration. The minimum average speed, minimum average positive acceleration and the minimum average negative acceleration were 29.50 mm/s, 45.18 mm/s2 and 42.64 mm/s2, respectively. Positive acceleration was higher than the negative acceleration. The copper content in tissues of juvenile silver carp was: liver>gill>muscle, but without significant difference among tissues. The study provides basic data and theoretical basis of water quality by monitoring fish behaviors changes to give early warning and comprehensive evaluation on the toxicity level.
2018, 42(1): 155-161.
DOI: 10.7541/2018.020
Abstract:
The effects of testosterone, estradiol and the combination of the two hormones on the main development stages and population growth rate of Asplanchna brightwelli were studied with ecological experiment methods. The results showed that the 48h LC50 of testosterone (T) was 9.56 mg/L, Y=1.9793X+3.0591 (R2=0.9211); 48h LC50 of estradiol (E) was 8.18 mg/L, Y=3.5292X+1.7788 (R2=0.9195). Testosterone and estradiol significantly reduced the lifespan, the number of offspring, and population growth rate (r) except the condition under the concentration of 0.5 mg/L. Treatment with testosterone at the concentration of 8 mg/L significantly prolonged the pre-reproductive time by 11.71%, and decreased the lifespan and the number of offspring by 52.22% and 82.20%, respectively. Treatment with estradiol at the concentration of 8 mg/L significantly prolonged the pre-reproductive time by 7.10%, and decreased the lifespan and the number of offspring by 49.75% and 83.33%, respectively. When the two hormones were at a total concentration of 8 mg/L, compared with the control groups, the pre-reproductive period significantly prolonged by 34.17%—48.01%; the mean life significantly shortened by 31.56%—42.12%; the number of offspring reduced by 24.44%—80.33%. At the 5d, the population growth rate of rotifers significantly declined by 30.00%, 37.14%, 41.43%, 60.00% and 65.71% when they were exposed to T6E2, T4E4, T8E0, T0E8 and T2E6, respectively. Consequently, testosterone and estradiol showed significant effects on the durations of different development stages of Asplanchna brightwelli and the characteristics of its population growth. Simultaneously, the two hormones showed synergistic effects and the rotifers were more sensitive to estradiol.
The effects of testosterone, estradiol and the combination of the two hormones on the main development stages and population growth rate of Asplanchna brightwelli were studied with ecological experiment methods. The results showed that the 48h LC50 of testosterone (T) was 9.56 mg/L, Y=1.9793X+3.0591 (R2=0.9211); 48h LC50 of estradiol (E) was 8.18 mg/L, Y=3.5292X+1.7788 (R2=0.9195). Testosterone and estradiol significantly reduced the lifespan, the number of offspring, and population growth rate (r) except the condition under the concentration of 0.5 mg/L. Treatment with testosterone at the concentration of 8 mg/L significantly prolonged the pre-reproductive time by 11.71%, and decreased the lifespan and the number of offspring by 52.22% and 82.20%, respectively. Treatment with estradiol at the concentration of 8 mg/L significantly prolonged the pre-reproductive time by 7.10%, and decreased the lifespan and the number of offspring by 49.75% and 83.33%, respectively. When the two hormones were at a total concentration of 8 mg/L, compared with the control groups, the pre-reproductive period significantly prolonged by 34.17%—48.01%; the mean life significantly shortened by 31.56%—42.12%; the number of offspring reduced by 24.44%—80.33%. At the 5d, the population growth rate of rotifers significantly declined by 30.00%, 37.14%, 41.43%, 60.00% and 65.71% when they were exposed to T6E2, T4E4, T8E0, T0E8 and T2E6, respectively. Consequently, testosterone and estradiol showed significant effects on the durations of different development stages of Asplanchna brightwelli and the characteristics of its population growth. Simultaneously, the two hormones showed synergistic effects and the rotifers were more sensitive to estradiol.
Abstract:
This study aimed to reconstruct total phosphorus (TP) concentration in the water column and to reveal the history of environmental changes since the 1970s in Shahu Lake based on subfossil chironomid assemblages analysis of a 41-cm length sediment core, combined with 210Pb dating, chironomid-inferred total phosphorus (CI-TP) transfer function in the middle and lower reaches of the Yangtze River, detrending correspondence analysis (DCA) and documentary data of Wuhan City. Three distinct stages were identified in chironomid assemblages. From 1973 to 1989, the dominance of macrophyte-related taxa (e.g. Cricotopus sylvestris and Dicrotendipes nervosus-type) indicated that the development of macrophytes in the lake, with CI-TP fluctuating from 47 to 55 μg/L. Meanwhile, sedimentary TP maintained around 700 mg/kg. From 1989 to 2000, sedimentary TP doubled its concentration and CI-TP increased to above 100 μg/L, concurrent with a marked decrease of the relative abundance in macrophyte-related taxa. These lines of evidence revealed that the lake had shifted from a mesotrophic status to a eutrophic condition. After 2002, sedimentary TP increased continuously to more than 2000 mg/kg. Concurrently, the chironomid assemblages were dominated by eutrophic species (i.e., Tanypus and Propsilocerus akamusi-type), with the CI-TP concentration above 150 μg/L. The first DCA axis captured 62.1% of total variance in the chironomid data and was significantly correlated with sedimentary TP, suggesting that variations in chironomid assemblages were mainly the consequence of nutrient enrichment. Lake eutrophication was in association with both lake area shrinkage and sewage inputs resulted from the urbanization in Wuhan City. This study revealed that the baseline TP concentration of Shahu Lake was around 50 μg/L and reducing external nutrient inputs is crucial for water environment protection.
This study aimed to reconstruct total phosphorus (TP) concentration in the water column and to reveal the history of environmental changes since the 1970s in Shahu Lake based on subfossil chironomid assemblages analysis of a 41-cm length sediment core, combined with 210Pb dating, chironomid-inferred total phosphorus (CI-TP) transfer function in the middle and lower reaches of the Yangtze River, detrending correspondence analysis (DCA) and documentary data of Wuhan City. Three distinct stages were identified in chironomid assemblages. From 1973 to 1989, the dominance of macrophyte-related taxa (e.g. Cricotopus sylvestris and Dicrotendipes nervosus-type) indicated that the development of macrophytes in the lake, with CI-TP fluctuating from 47 to 55 μg/L. Meanwhile, sedimentary TP maintained around 700 mg/kg. From 1989 to 2000, sedimentary TP doubled its concentration and CI-TP increased to above 100 μg/L, concurrent with a marked decrease of the relative abundance in macrophyte-related taxa. These lines of evidence revealed that the lake had shifted from a mesotrophic status to a eutrophic condition. After 2002, sedimentary TP increased continuously to more than 2000 mg/kg. Concurrently, the chironomid assemblages were dominated by eutrophic species (i.e., Tanypus and Propsilocerus akamusi-type), with the CI-TP concentration above 150 μg/L. The first DCA axis captured 62.1% of total variance in the chironomid data and was significantly correlated with sedimentary TP, suggesting that variations in chironomid assemblages were mainly the consequence of nutrient enrichment. Lake eutrophication was in association with both lake area shrinkage and sewage inputs resulted from the urbanization in Wuhan City. This study revealed that the baseline TP concentration of Shahu Lake was around 50 μg/L and reducing external nutrient inputs is crucial for water environment protection.
2018, 42(1): 171-181.
DOI: 10.7541/2018.022
Abstract:
In the polyculture ponds dominated with grass carp (Ctenopharyngodon idellus), the physico-chemical index and community structure of plankton and microbial in pond water with or without fermented organic fertilizer were measured to analyze the effects of fermented organic fertilizer on water environment of polyculture ponds. The results showed that the diversity and biomass of zooplankton, phytoplankton and bacteria increased significantly in the fermented organic fertilizer ponds. During the experiment, monthly average biomass of phytoplankton, zooplankton, and the average abundance of microbial were (68.21±25.13) mg/L, (9.83±5.74) mg/L and (6.53±2.13)×106 ind./mL, which were 2.78, 4.35 and 1.29 times of those in the control ponds, respectively. Furthermore, the proliferations of beneficial bacteria were significantly promoted by using fermented organic fertilizer. In later stage, the relative proportions of Lactobacillus, Bacillus and Arthrobacter were (0.61±0.17)%, (0.89±0.29)% and (0.04±0.0082)%, which were 3, 3 and 4 times of those in the control ponds, respectively. In rapid accumulation season of -N and -N, the concentrations of -N and -N were significant lower than those of control ponds (P<0.05), which indicated that the fermented organic fertilizer had a remarkable effect on stabilizing the concentration of -N and -N. Moreover, the oxygenation improved significantly by fermented organic fertilizer, while the pH value, TN, TP, -N, and -P concentration were not significantly different (P>0.05) from those of the control ponds. All of the results mentioned above indicated that the effectiveness of fermented organic fertilizer was prominent and it could significantly improve the water environment of polyculture ponds.
In the polyculture ponds dominated with grass carp (Ctenopharyngodon idellus), the physico-chemical index and community structure of plankton and microbial in pond water with or without fermented organic fertilizer were measured to analyze the effects of fermented organic fertilizer on water environment of polyculture ponds. The results showed that the diversity and biomass of zooplankton, phytoplankton and bacteria increased significantly in the fermented organic fertilizer ponds. During the experiment, monthly average biomass of phytoplankton, zooplankton, and the average abundance of microbial were (68.21±25.13) mg/L, (9.83±5.74) mg/L and (6.53±2.13)×106 ind./mL, which were 2.78, 4.35 and 1.29 times of those in the control ponds, respectively. Furthermore, the proliferations of beneficial bacteria were significantly promoted by using fermented organic fertilizer. In later stage, the relative proportions of Lactobacillus, Bacillus and Arthrobacter were (0.61±0.17)%, (0.89±0.29)% and (0.04±0.0082)%, which were 3, 3 and 4 times of those in the control ponds, respectively. In rapid accumulation season of
2018, 42(1): 182-189.
DOI: 10.7541/2018.023
Abstract:
Selection of microalgae strains that are capable of utilizing high concentration of CO2 is essential for industrial application. At present, the microalgae research mainly focus on the biomass, bioactive products and recovery properties, rather than physiological properties. The influence of different CO2 concentrations, including air, 5% CO2 and 20% CO2 (v/v), on the growth and physiological properties of Chlorella sp. FACHB-1580 and Scenedesmus sp. FACHB-1618 were studied. The goal was to clarify the relationship between the physiological properties and the CO2 utilizing capacity. Results showed that both strains were capable to use high concentration of CO2 and had the maximum biomass accumulation, specific growth rate and CO2 fixation rate under 5% CO2 (v/v) culture condition. The maximum biomass was 3.5 g/L in Chlorella sp. FACHB-1580 and 5.4 g/L in Scenedesmus sp. FACHB-1618 which was 1.41 and 1.46 times higher in comparison with the control (air) group, respectively. Both strains had higher biomass under 20% CO2 (v/v) condition than that in the air group (P < 0.05). With the increasing supply of CO2, the affinity of inorganic carbon, the activity of intracellular (CAint) and extracellular (CAext) carbonic anhydrase, as well as the initial activity and activation rate of Rubisco declined in both strains. However, there was no significant difference in the total Rubisco activity across time. In addition, Chlorella sp. FACHB-1580 had significantly higher levels of CAint and CAext activities. By contrast, Scenedesmus sp. FACHB-1618 had very poor CAint and CAext activities and were not detectable, indicating these two strains differed significantly in the utility of inorganic carbon. It was speculated that Chlorella sp. FACHB-1580 can absorb both CO2 and whereas the Scenedesmus sp. FACHB-1618 tends to only absorb CO2. Chlorella sp. FACHB-1580 may obtain its abundant CO2 for Rubisco via high CAint activity; for Scenedesmus sp. FACHB-1618, due to its lower CAint activity, it may increase the amount of CA protein, or higher carboxylase affinity for CO2 to promote the reactions of photosynthesis.
Selection of microalgae strains that are capable of utilizing high concentration of CO2 is essential for industrial application. At present, the microalgae research mainly focus on the biomass, bioactive products and recovery properties, rather than physiological properties. The influence of different CO2 concentrations, including air, 5% CO2 and 20% CO2 (v/v), on the growth and physiological properties of Chlorella sp. FACHB-1580 and Scenedesmus sp. FACHB-1618 were studied. The goal was to clarify the relationship between the physiological properties and the CO2 utilizing capacity. Results showed that both strains were capable to use high concentration of CO2 and had the maximum biomass accumulation, specific growth rate and CO2 fixation rate under 5% CO2 (v/v) culture condition. The maximum biomass was 3.5 g/L in Chlorella sp. FACHB-1580 and 5.4 g/L in Scenedesmus sp. FACHB-1618 which was 1.41 and 1.46 times higher in comparison with the control (air) group, respectively. Both strains had higher biomass under 20% CO2 (v/v) condition than that in the air group (P < 0.05). With the increasing supply of CO2, the affinity of inorganic carbon, the activity of intracellular (CAint) and extracellular (CAext) carbonic anhydrase, as well as the initial activity and activation rate of Rubisco declined in both strains. However, there was no significant difference in the total Rubisco activity across time. In addition, Chlorella sp. FACHB-1580 had significantly higher levels of CAint and CAext activities. By contrast, Scenedesmus sp. FACHB-1618 had very poor CAint and CAext activities and were not detectable, indicating these two strains differed significantly in the utility of inorganic carbon. It was speculated that Chlorella sp. FACHB-1580 can absorb both CO2 and
2018, 42(1): 190-195.
DOI: 10.7541/2018.024
Abstract:
The growth, pigment content, maximum variable fluorescence (Fv/Fm), malondialdehyde (MDA) content, and antioxidant enzyme activity were investigated in Microcystis aeruginosa PCC 7806 and a green alga, Chlorella sp. FACHB-31, which were cultured under darkness and at a low-temperature in the present study. After a 30-d incubation under darkness and at a low temperature, chlorophyll a showed a significant decrease and the carotenoid unit content significantly increased in Microcystis and Chlorella. The MDA content and catalase (CAT) activity exhibited significant changes in Microcystis, while MDA content and CAT activity in Chlorella did not change markedly. Additionally, the survival rate of Microcystis was 54.6%, which is higher than that of Chlorella (31.3%). When returning to normal temperature and illumination, both algae showed a rapid growth. These results suggest that Microcystis survived by reducing its metabolic activity, but that Chlorella maintained a stable high metabolic activity under dark, low temperature winter conditions.
The growth, pigment content, maximum variable fluorescence (Fv/Fm), malondialdehyde (MDA) content, and antioxidant enzyme activity were investigated in Microcystis aeruginosa PCC 7806 and a green alga, Chlorella sp. FACHB-31, which were cultured under darkness and at a low-temperature in the present study. After a 30-d incubation under darkness and at a low temperature, chlorophyll a showed a significant decrease and the carotenoid unit content significantly increased in Microcystis and Chlorella. The MDA content and catalase (CAT) activity exhibited significant changes in Microcystis, while MDA content and CAT activity in Chlorella did not change markedly. Additionally, the survival rate of Microcystis was 54.6%, which is higher than that of Chlorella (31.3%). When returning to normal temperature and illumination, both algae showed a rapid growth. These results suggest that Microcystis survived by reducing its metabolic activity, but that Chlorella maintained a stable high metabolic activity under dark, low temperature winter conditions.
2018, 42(1): 196-205.
DOI: 10.7541/2018.025
Abstract:
To investigate the species diversity of Thalassiosira in China and provide molecular data for further phylogenetic studies, monoclonal strains have been isolated and established from some representative sites in Chinese coast. The morphology was studied using light and electron microscopy, and the hypervariable D1‒D3 region of the nuclear large subunit ribosomal RNA-encoding gene region (LSU rRNA gene) was amplified and sequenced. Two newly recorded Thalassiosira species (T. anguste-lineata (Schmidt) Fryxell & Hasle and T. minicosmica Lee & Park) for China were reported based on the combination of morphology and molecular data. Their detailed morphology were described and compared with allied taxa. The results of molecular phylogenetic tree based on sequences data of D1—D3 region of LSU rRNA indicated that neither T. anguste-lineata nor T. minicosmica were clustered with T. nordenskioeldii, the type species of the genus Thalassiosira, suggesting great genetic difference is present among Thalassiosira taxa, and that the present morphology-based genus Thalassiosira is not a natural group because it is separated by some other allied genus, such as Skeletonema, Cyclotella, Planktoniella. These results revealed that the present reported Thalassiosira species should be paraphyletic group and will be gradually revised into multiple independent genera in future phylogenetic study. However, it is difficult to carry out specific taxonomic revisions because of limited molecular data that is an important constraint for the advancement of related researches.
To investigate the species diversity of Thalassiosira in China and provide molecular data for further phylogenetic studies, monoclonal strains have been isolated and established from some representative sites in Chinese coast. The morphology was studied using light and electron microscopy, and the hypervariable D1‒D3 region of the nuclear large subunit ribosomal RNA-encoding gene region (LSU rRNA gene) was amplified and sequenced. Two newly recorded Thalassiosira species (T. anguste-lineata (Schmidt) Fryxell & Hasle and T. minicosmica Lee & Park) for China were reported based on the combination of morphology and molecular data. Their detailed morphology were described and compared with allied taxa. The results of molecular phylogenetic tree based on sequences data of D1—D3 region of LSU rRNA indicated that neither T. anguste-lineata nor T. minicosmica were clustered with T. nordenskioeldii, the type species of the genus Thalassiosira, suggesting great genetic difference is present among Thalassiosira taxa, and that the present morphology-based genus Thalassiosira is not a natural group because it is separated by some other allied genus, such as Skeletonema, Cyclotella, Planktoniella. These results revealed that the present reported Thalassiosira species should be paraphyletic group and will be gradually revised into multiple independent genera in future phylogenetic study. However, it is difficult to carry out specific taxonomic revisions because of limited molecular data that is an important constraint for the advancement of related researches.
2018, 42(1): 206-211.
DOI: 10.7541/2018.026
Abstract:
The information on Rotifera of Hainan Island is limited. To examine the species composition of the Rotifera on Hainan Island, 134 samples were collected from 134 freshwater habits (reservoirs, ponds, temporal ponds, brooks, rivers and rice fields) in November 2010, May and August 2011. Twenty-four species of the genera Trichocerca were identified. Trichocerca agnatha, T. obtusidens, T. rosea and T. pygocera are new to the Oriental Zone, and T. agnatha and T. braziliensis are new to China. Trichocerca pusilla, T. similis, T. braziliensis and T. tenuior are the most common species in this genus. The majority of Trichocerca on Hainan island was widely distributed. There are seventeen cosmopolitan species, three cold-water taxa and two warm-water taxa. The diversity of Trichocerca on Hainan island is much higher than that in the other regions of China, and Bray-Curtis dissimilarity of Trichocerca between Hainan island and the other regions of China increases with higher latitudes.
The information on Rotifera of Hainan Island is limited. To examine the species composition of the Rotifera on Hainan Island, 134 samples were collected from 134 freshwater habits (reservoirs, ponds, temporal ponds, brooks, rivers and rice fields) in November 2010, May and August 2011. Twenty-four species of the genera Trichocerca were identified. Trichocerca agnatha, T. obtusidens, T. rosea and T. pygocera are new to the Oriental Zone, and T. agnatha and T. braziliensis are new to China. Trichocerca pusilla, T. similis, T. braziliensis and T. tenuior are the most common species in this genus. The majority of Trichocerca on Hainan island was widely distributed. There are seventeen cosmopolitan species, three cold-water taxa and two warm-water taxa. The diversity of Trichocerca on Hainan island is much higher than that in the other regions of China, and Bray-Curtis dissimilarity of Trichocerca between Hainan island and the other regions of China increases with higher latitudes.
2018, 42(1): 212-220.
DOI: 10.7541/2018.027
Abstract:
Diatoms are one of the most important primary producers in aquatic ecosystems. Diatoms can provide carbon source for consumers in ecosystems. They are regarded as good indicators of environmental changes, due to their wide distribution, species abundance and short generation time. In this paper, we reviewed the vital role and characteristics of diatoms in aquatic ecosystems, especially in river ecosystems. We also described the responses of diatoms to environmental variables at individual, population, and community levels. The current status and prospects of diatoms (and the diatom index) in the monitoring and assessment of river ecosystem health were also discussed. We introduced the theory and history of the development of diatom indices in general, indices which are now used widely throughout the world, and particularly we discussed the diatom based index of biotic integrity (IBI) in terms of methods, principal and application. The problems associated with the application of diatom based IBI were pointed out.
Diatoms are one of the most important primary producers in aquatic ecosystems. Diatoms can provide carbon source for consumers in ecosystems. They are regarded as good indicators of environmental changes, due to their wide distribution, species abundance and short generation time. In this paper, we reviewed the vital role and characteristics of diatoms in aquatic ecosystems, especially in river ecosystems. We also described the responses of diatoms to environmental variables at individual, population, and community levels. The current status and prospects of diatoms (and the diatom index) in the monitoring and assessment of river ecosystem health were also discussed. We introduced the theory and history of the development of diatom indices in general, indices which are now used widely throughout the world, and particularly we discussed the diatom based index of biotic integrity (IBI) in terms of methods, principal and application. The problems associated with the application of diatom based IBI were pointed out.