Myxobolus haichengensis Chen, 1958 forms numerous small plasmodia on the gill filaments of wild cyprinid Abbottina rivularis Basilewaky. The species described originally was lacking important characters, which made the accurate identification difficult. Here, we supplemented its characteristics with morphological and molecular data. Plasmodia of M. haichengensis are oval. Mature spores are ellipsoidal-shaped in frontal view and fusiform-shaped in lateral view, measuring (10.8±0.7) μm (10.1—11.5 μm) long, (8.1±0.5) μm (7.5—9.0 μm) wide, and (5.7±0.4) μm (5.2—9.0 μm) thick; two unequal polar capsule are pyriform with tapering anterior, large polar capsule averaging (4.7±0.5) μm (4.8—6.7 μm) long and (2.5±0.2) μm (3.2—4.3 μm) wide; small polar capsule averaging (4.4±0.2) μm (4.1—4.8 μm) long and (2.2±0.1) μm (2.0—2.5 μm) wide; polar filaments coil with four to five turns. The nuclear 18S rDNA sequence was obtained and deposited in GenBank (KY965936), and sequences alignment analyses revealed that M. haichengensis was most similar with the actinosporean Hexactinomyxon type 2 (AY162272, 97%) released from the freshwater tublificid oligochaete Limnodrilus hoffmeisteri.
Food quality can significantly affect the phosphorus content, growth, reproduction, as well as physiological behavior of zooplankton, leading to regulate the energy transfer efficiency at the primary producer-consumer interface. However, the elemental coupling between zooplankton and food is scarcely observed at the community level. In this study, the elemental coupling and the elemental imbalances between seston and mesozooplankton assemblage in addition to the ecological impacts of such imbalances on zooplankton-phytoplankton interaction were detailed by analyzing the compositions of carbon, nitrogen, and phosphorus in seston and mesozooplankton assemblage derived from 13 samples containing water bodies in the Hubei province, China. The achieved results showed that both C﹕N and C﹕P ratios in mesozooplankton were positively correlated with the corresponding ratios in seston. Besides, the elemental imbalances between seston and mesozooplankton were positively correlated with the corresponding seston ratio (C﹕N,r=0.97, P<0.001; C﹕P,r=0.81, P=0.001). Further analysis also revealed that the energy transfer efficiency between zooplankton and phytoplankton declined with the increase of elemental imbalance in C﹕P ratio (r= –0.58, P=0.037). Moreover, a similar decline in zooplankton biomass was found as well as increase of imbalance in C﹕P ratio (r= –0.59, P=0.033). These results indicated that seston stoichiometry could remarkably impact the elemental stoichiometry of mesozooplankton assemblage, and the elemental imbalances tended to be greater with the increase of seston stoichiometry; consequently, the energy transferred to mesozooplankton was decreased as well.
In order to comprehensively evaluate the eutrophication status in China lakes, this study scientifically analyzed the eutrophication and its regional heterogeneity in 22 representative lakes of China, and the quantitative relationship between TP and eutrophication was also studied. The results showed that 59.1% of the surviving lakes are in different eutrophication status from 2010 to 2011. Among them, Yunnan-Guizhou Lake area has the highest eutrophication level, but Menggu-Xinjiang Lake area has a bipolar levels. The lakes at Northeast Mountain and Plain area, and also the lakes at eastern area generally have a level between middle nutrition to mild eutrophication. The lowest eutrophication level is at the area of Qinghai-Tibet Plateau. Based on the relationship between sunshine amount, frost-free period, temperature, water depth, altitude, precipitation and lake nutrition status, it reveals that the geographical location of lakes is the fundamental factor affecting lake eutrophication and its regional distribution. The results of comprehensive analysis showed that there is a significant correlation between chlorophyll a and total phosphorus concentrations in lakes nationwide. Cubic curve regression equation fits the relation between chlorophyll a and total phosphorus concentrations at the areas of eastern plain, northeastern plain - mountain, Qinghai - Tibet Plateau and Yun - Gui Plateau. S-curve equation fits the relation between concentrations of chlorophyll a and total phosphorus in the Menggu-Xinjiang Lake area. With the increase of total phosphorus concentration, there was a minimum value of chlorophyll concentration in the lake areas of eastern plain, northeastern plain - mountain, Qinghai -Tibet Plateau at the beginning, and then followed by a maximum value. The minimum concentrations of total phosphorus in the three lake areas were 0.054 mg/L, 0.089 mg/L and 0.072 mg/L, respectively. This study can provide information for the control of lake eutrophication in future.
Submerged macrophytes have an important effect on the restoration of the degraded aquatic ecosystem, and the light intensity is the main limiting factor for its growth and development. This study investigated 7 different light intensities (100%, 60%, 40%, 20%, 10%, 5% and 1% of natural light) on the morphological index (plant height, leaf number) and physiological index (chlorophyll, root activity, antioxidant enzyme activity and malondialdehyde), of Potamogeton crispus to provide the theoretical basis for the construction of eutrophic water plant community. The results showed: (1) With the increase of light intensity, the plant heights, leaf numbers and biomass growth rate increased significantly, but the growth was inhibited in high light intensity (CK group) and the low intensity (1% group). (2) The chlorophyll content of P. crispus increased first and then decreased with the increase of light intensity. The contents of Chl. a, Chl. b, Chl. a + b and Car in 1% and CK groups were lower than those of the others. (3) With the extension of the test time, the root activity increased first and then decreased with higher root activity in the group of 20%, 40% and 60%. (4) The activity of SOD, POD and CAT increased first and then decreased during the whole experiment, and in the later stage of experiment, 1% and CK groups had higher content of SOD but lower content of POD and CAT. The content of MDA of leaf increased during the experiment associated with reduced growth of P. crispus. The best growth conditions of P. crispus were the 20%—60% of natural light, and the sustained weak light stress would cause the metabolism disorders of active oxygen, cells damage, and ultimate death.
In order to investigate the effects of indole-3-acetic acid (IAA) on physiological characteristics of Microcystis aeruginosa (M. aeruginosa), the growth, photosynthetic pigment content, chlorophyll fluorescence, lipid oxidation, and microcystin biosynthesis characteristics were studied. The achieved results showed that there was no significant variation in cell density, chlorophyll content, chlorophyll fluorescence characteristics, and microcystin contents at low concentrations of IAA (e.g., 0.04 and 0.2 mg/L). However the contents of phycocyanin, allophycocyanin, and malondialdehyde (MDA) decreased in comparison with the control group. High concentrations of IAA (0.04 and 0.2 mg/L) accelerate the algal growth and increased chlorophyll content, while that inhibited the contents of phycocyanin and allophycocyanin and reduced the peroxidation of membrane lipid peroxidation as well as synthetization of intracellular algal toxins. The findings also demonstrated that low concentrations of IAA have no clear influence on the growth and photosynthesis of M. aeruginosa CHAB-6301. However, high concentrations of IAA can promote the growth and photosynthesis of this alga, which may increase the possibility of formation of Microcystis-based water blooms.
Thalassiosira Cleve is one of the most speciose marine diatom genera, that has been globally distributed. To assess the diversity of the genus Thalassiosira species, monoclonal strains were isolated and established from Chinese coast. The morphology was observed by using a light microscope (LM) and a scanning electron microscope (SEM). Sequences of the large subunit (LSU) and small subunit (SSU) of the nuclear rRNA-encoding genes (rDNA) were obtained to form a phylogenetic relationship. Among 14 established Thalassiosira allenii (T. allenii) Takano strains, morphological variation was found involving some with and without marginal ribs on the valve edge. After comparing with the original description of T. allenii, the strains without marginal ribs were assigned as a type of T. allenii, and those with marginal ribs were proposed as a new variety, T. allenii var. striata. Morphological divergence was supported by molecular data as well. On the phylogenetic trees inferred from both LSU and SSU of the nuclear rDNA, accordingly, T. allenii was clustered with var. striata, and formed as sister groups (Bayesian posterior probability (BPP) > 0.90), demonstrating their firm relationship. SSU sequences are totally identical, without any different base pair, between these two varieties. However, 11 different base pairs among 556 LSU base pair, which used for analysis, could be found, and divergence of distance among them is only 0.01.
HSJ296, a Scenedesmus strain isolated and purified by this lab, can grow heterotrophically in the dark and contains a relatively high amount of α-linolenic acid. Comparisons of heterotrophic growth at different temperatures and concentrations of glucose, or with different nitrogen sources, indicated that the optimal culture conditions included 30℃, 4 g/L urea and 20—40 g/L glucose. As shown with fatty acid composition analyses under different conditions, the fatty acids of HSJ296 were mainly composed of hexadecanoic acid (C16:0), oleic acid (C18:1), linoleic acid (C18:2) and α-linolenic acid (α-C18:3), and the α-linolenic acid content in total lipids was between 35%—45% in independent experiments. The fermentation product of Scenedesmus HSJ296 may be used as a fish dietary supplement to supply α-linolenic acid and other nutrients.
In this study, an oil-producing alga was isolated and identified from soil at Pangquangou National Nature Reserve (Shanxi province, China), and cultivated under axenic conditions. Based on morphological observations, it was similar to the genus Chlorella. The phylogenetic analysis according to ribulose-bisphosphate carboxylase gene (rbcL) and 18S ribosomal RNA (18S rDNA) showed that it has the highest homology with Ch. vulgaris, so the strain was identified as Ch. vulgaris PQG67. It produced a lipid content within 30% after continuous culture with different light intensities, as well as more than 40% after affecting by salt (NaCl) stress. Fourier-transform infrared spectroscopy (FTIR) of the produced oil showed lipid band intensity from spectra vCO at 1634/cm, and continued to increase in Ch. vulgaris PQG67 cells during experimental test. The alga possessed high biomass and oil-producing potentials for utilization in biodiesel production.
Illex argentinus is one of the most important ommastrephid squids, due to its annual landing volume, and its key role as transient ‘biological pumps’ in southwest Atlantic ecosystem. In order to understand the fecundity characteristics of male ommastrephids, specimens of male I. argentinus, collected from December 2012 to March 2013, were used to analyze the fecundity and its relationship to reproductive development with biological statistics analysis. The results showed that the minimum biological size was 207.29 mm for mantle length (ML) and 162.55 g for body weight (BW). The effective fecundity (EF), defined as the sum of normal spermatophores in spermatophoric complex and spermatophoric sac, was in an average of (374±280.33) spermatophores. The mean value of relative effective fecundity by mantle length was (179.18±117.66) spermatophores per millimeter. The length of spermatophores (SL) varied from 6.34 to 33.14 mm, and its mean value was (21.57±4.17) mm, which was (10.22±1.82)% of mantle length. Both EF and SL significantly increased with the onset of sexual maturation (P<0.05). EF attained the maximum value at functionally maturity stage (VI), with a mean value of (811±181.34) spermatophores. SL increased up to the mating stage (VII), whereby it attained a mean value of (23.89±3.87) mm. Meanwhile, both EF and SL showed significantly linear relation with mantle length (EF=–581.92+4.56ML, R2=0.17, P<0.05;SL=5.77+0.075ML, R2=0.23, P<0.05) and body weight (EF=16.55+1.77BW, R2=0.37, P<0.05;SL=17.96+0.017BW, R2=0.17, P<0.05), indicating that individual with bigger size has larger EF and longer SL. Furthermore, the compare datasets of fitted model analysis revealed that there was no significant difference between the linear relationship of EF-ML and that of EF-BW (P>0.05). Based on multiple regression analysis, however, the influence on EF from body weight was more significant than that from mantle length (P<0.05). The compare datasets of fitted model analysis for SL showed that there was significant difference between the linear relationship of SL-ML and that of SL-BW (P<0.001), although the multiple regression analysis suggested a comparative influence on SL from both mantle length and body weight (P<0.001). These findings indicated that the EF of maleI. argentinus was a strategy of adaptability to its short lifespan by producing and accumulating spermatophores along with reproductive development and body growth, and the length of spermatophores will also increase with time.
The Asian giant softshell turtle Pelochelys cantorii (Trionychidae) is seriously endangered and has designated as the first grade of protected animal in China in 1989. In 2000, it has been listed as endangered species by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and put on par along with the Giant panda Ailuropoda melanoleuca and the white-flag dolphin Lipotes vexillifer. This animal typically suffers from gradual reduction in its total population because of inadequate safety, food, and health protections. Sparse data, extensively referred in the literature, emphasize on the reproductive for this species, in order to enhance individuals’ knowledge about the reproduction of P. cantorii. For this purpose, we attempted to study the nesting behavior, clutch size, egg size, incubation period, as well as other reproductive characteristics of 4 adults (2♂, 2♀) under captive conditions from 2015 to 2017. Oviposition season is commenced from May to August; the egg-laying behaviors are typically occurred at the night. Clutches are made up of eggs with spherical and rigid shells without parental care behaviors. All adult females laid 5—6 clutches [mean egg number=(42.6±5.3); (32—55); n=21] during the breeding season in 2015 and 2016. In 2016, the mean egg’s mass, egg’s diameter, and mass of the newly hatchings were (16.82±1.99) g (n=476), (3.10±0.18) cm (n=476), and (13.60±0.85) g (n=202), respectively. Analysis of reproductive data obtained by 2016 based on the size and mass of the eggs, which were positively correlated (r=0.916, P<0.01), showed that there was no significant difference in average size of clutch between these two females (Using analysis of variance (ANOVA),F1,9=0.442, P=0.283). The weight of female No. 1 was more than that of female No. 2, the mass of female No. 1’s egg and newly hatchings were both more than that of female No. 2 as well. The juveniles fed by live fish seedlings could be reared to (510.30±82.77) g in the greenhouse for one year. The achieved findings affiliated with reproduction traits in P. cantorii can shield some light, and those results might be used to improve the conservation of the species.
This study conducted isolation, identification and drugs sensitivity of pathogen from sick Trionyx sinensis to provide a reference for control and prevention disease for Trionyx sinensis. The pathogenic bacteria were isolated and purified from skin, liver, kidney and spleen of Trionyx sinensis. The identification of the isolated pathogen was analyzed by biochemical reactions and 16S rRNA gene sequence. The artificial infection test was performed with intraperitoneal injection, and drugs susceptibility test was conducted by K-B method and double broth dilution method. The results showed that strain J22 was the pathogen of Trionyx sinensis, and the LD50 was 3.30×104 CFU/g. According to morphological and biochemical characteristics as well as 16S rRNA gene sequence analysis, strain J22 was identified as Chryseobacterium indologenes. Strain J22 was susceptible to neomycin, gentamicin and amoxicillin and other 9 antibiotics but resistant to florfenicol and doxycycline, etc. The chlorine dioxide, bleaching powder and potassium ferrate had great antiseptic effect on the isolated pathogeb. These results indicate that Strain J22-induced disease of Trionyx sinensis can be treat by drugs such as neomycin, gentamicin and amoxicillin for oral administration, and that chlorine dioxide, bleaching powder and potassium ferrate are suitable for external use in farming.
In this study, the cDNA sequence of Vitellogenin (Vtg) gene in Chinese sturgeon Acipenser sinensis was amplified with the rapid amplification of cDNA end (RACE) method, and its theoretical molecular mass is 196 kD. The antigenic site of the encoded amino acid sequence was cloned, which was used to construct recombinant plasmid and express recombinant protein. The polyclonal antiserum was obtained by immunizing rabbits with purified recombinant protein, and its specificity to Vtg was examined by western blotting. A competitive Enzyme-linked immunosorbent assay (ELISA) was established to detect Vtg in the serum of A. sinensis using antiserum of Vtg as antibody and the purified recombinant protein as antigen. The linear regression of the standard curve was y=–0.2916x+0.6794 (R2=0.9976). The sensitivity of this method was 4.12 μg/mL, and the lowest threshold for detection was 0.3 μg/mL. The inter- and intra-assay coefficients of variation was 2.52% (n=3) and 3.42% (n=3), respectively. The test results of blood sample for the female A. sinensis at different developmental stages showed that the method could be used to monitor the gonadal development of female Chinese sturgeon.
Ink turtle is one stain of P. sinensis in south Anhui province, which is very popular in local market. In this study, the differences of basic nutrient compositions, including amino acid and fatty acid contents in the muscles, and collagen contents in the calipash of four strains of P.sinensis were compared, which are ink turtle, wild turtle, Huai River turtle, and T. japonicus. The results showed as follows: (1) the moisture contents in the muscles of four strains were 80.40%, 79.48%, 81.57% and 79.25%, respectively. The moisture contents in ink turtles and Huai River turtles were significantly higher than those in the wild turtle and T. japonicas (P<0.05). The crude protein contents in the four strains were 17.82%, 17.60%, 15.93% and 16.40%, respectively. The crude protein content in ink turtle was the highest, which was significantly higher than that in the Huai River turtle andT. japonicus (P<0.05). The crude fat contents were 0.42%, 1.43%, 0.65% and 1.06%, respectively. The crude fat content in ink turtles was significantly lower than that in other strains (P<0.05), while the ash showed no significant difference among each other (P>0.05). (2) The ink turtle had the highest contents of TAA and DAA in muscles. (3) The UFA in the four strains ofP. sinensis was 65.19%, 56.44%, 59.20% and 54.73%, respectively, which was significantly higher in the ink turtle than in other strains (P<0.05). The content of MUFA in ink turtle was significantly lower than in wild turtle, while the content of PUFA in ink turtle was significantly higher than in other strains (P<0.05). The contents of SFA in the four strains ofP. sinensis were 35.20%, 41.85%, 39.41% and 39.98%, respectively, which was significantly lower in ink turtle than that in other strains (P<0.05). (4) The contents of DHA and EPA in ink turtle were significantly higher than those in the Huai River turtle andT. japonicus , which had no significant difference with those in wild turtle. AA in muscles of ink turtle was significantly higher than that in other stains (P<0.05). (5) There was no obvious difference in the collagen content at calipash among the four strains ofP. sinensis (P>0.05). Therefore, the ink turtle is an indigenous strain with high nutritive value and delicious flavor.
Age structure and growth characteristics of Culter alburnus provide a theoretical basis for the artificial reproduction, sexual maturity age, survival rate to optimize the structure of fish stocks, the scientific use of its germplasm resources and to provide reference resource utilization and conservation of the species. To study the relationship between age structure and growth characteristics, a total of 452 Culter alburnus individuals were collected in the Dianshan Lake from May 2016 to July 2017. The results showed that the body length of Culter alburnus ranged from 15.32 to 77.91 cm, and that body weight ranged from 43 to 5567 g. There were no significant differences in body length and body weight between female and male (P>0.05). The relationship between body weight and body length was described by the linear equation: W=0.00002L2.9211 (R2=0.9143, n=452), which is consistent with uniform growth characteristics. The growth pattern of Culter alburnus was described by the von Bertalanffy equation as Lt=99.65[1–e–0.1357(t+0.6287)], Wt=11874.27[1–e–0.1357(t+0.6287)]2.9211, selection of scale identification age, measurement scale radius. The age of the fish ranged from one to six years with dominated ones with three year-old (55.71%), which revealed a growth trend of youth and miniaturization. The inflection point of the growth curve occurred at 7.2711 years with a body length of 65.54 cm and weight of 3471.79 g.
According to previous studies on fish angling, a correlation has been established between vulnerability to angling and metabolic traits in fish. However, it still remains unknown that whether other phenotypes (i.e., swimming performance and personality) of fish are related to the vulnerability to angling. To examine the phenotypic basis, ecological consequences and fasting responses to angling in Cyprinids fish, juvenile gibel carp (Carassius auratus gibelio) was used as experimental model in this study. This study first measured the phenotypic traits (i.e. energy metabolism, swimming performance and personality) of the experimental fish, and then the fish were angled in the buckets (named as control group) under laboratory condition. After all measurements of phenotypes and angling having been completed, all fish were fasted for 7 days and angled again at the end of fasting period (named as fasting group), following by a 14-day period of continuous feeding (named as refeeding group). There were four parallel angling samples (n=40 individuals per sample) in each angling test, which was ceased when the 20th individual was successfully angled. The angled 20 individuals were considered as angling group (i.e. higher vulnerability to angling), and the other 20 individuals were considered as un-angling group (i.e. lower vulnerability to angling). The factorial aerobic scope of the angling group was smaller than that of the un-angling group. The results showed that no differences in morphology (body weight, body length and condition factor), energy metabolism (standard metabolic rate, SMR; maximum metabolic rate, MMR; and aerobic scope, AS), swimming performance (maximum accelerated swimming capacity, Ucat; and gait transition speed, Ugt), and personality (exploration, activity and boldness) between the angling group and the un-angling group. The fish had a higher percent latency in the exploration test than that in the boldness test, which led to shorter time spent in moving and lower frequency in passing through door in the exploration test than those in the boldness test. SMR was not related to Ucat and Ugt (P>0.05), whereas MMR and AS were positively correlated with bothUcat and Ugt (P<0.05). The energy metabolic parameters were related to some personality parameters. Fasting increased the total angling time, average individual angling time and coefficient variance of the individual angling time in juvenile gibel carp. The specific growth rate (SGR) of body mass was higher in the un-angling group than that in the angling group during the fasting period, but no difference in SGR was found between the un-angling group and the angling group during the refeeding period. With the exception of MMR and AS, SMR was negatively related to SGR during both the fasting period and the refeeding period (P<0.05), suggesting that higher SMR individuals decreased their body mass faster during fasting, and grew slower during refeeding. Our study suggested that the juvenile gibel carp may not have the phenotypic basis, and would decrease their vulnerability to angling due to fasting. There was difference in the ecological consequences between two phenotypes of vulnerability to angling, but this difference disappeared after the 14-day period of refeeding, indicating that the vulnerability to angling of the juvenile gibel carp is context-dependent to some extent.
Starvation is a special period when fish cannot effectively obtain food, resulting to some problems (i.e., lack of energy required). DHA (Docosahexaenoic acid), being highly unsaturated fatty acids retained in body during starvation, is postulated to contain special energy regulation effect on the starving fish body. To explore the effect of DHA fortification on body weight loss and lipid metabolism of starved common carp (Cyprinus carpio L.) in two dietary lipid levels, a feeding trail, which followed with starvation, was conducted. Firstly, 3% DHA product was added to 6% and 12% lipid levels diets to formulate four different kinds of diet respectively, (i.e., basic diet, basic-DHA diet, high lipid diet, and high lipid-DHA diet). A total of 360 common carp (14.81±0.13) g/tail were randomly divided into four groups (triplicate per each group), fed with four diets and reared in a recycling water rearing tanks, respectively. After 74 days of feeding, some fish per each tank were sampled and eventually 6 fish per each tank were left to endure 36 days of starvation. Then, all staved fish were sampled and weight of fish and the relative indexes were determined. Result showed that the body weight loss ratio of fish in DHA groups was significantly higher than that of the non-DHA groups in the same lipid level. Besides, the hepatocyte diameter and lipid content in muscle and intestine of starved fish in DHA groups were remarkably lower than that of the non-DHA groups (P<0.05). The lipid content in hepatosomatic and serum biochemical index of fish showed that there is no significant difference. The achieved result demonstrated that DHA fortification dietary groups had significantly lower body weight, hepatocyte diameter, as well as lipid content of muscle and intestine in starved common carp, which may reflect that DHA fortification had no great advantages in fostering common carp endure starvation.
The study was conducted to evaluate the effects of dietary protein levels on evolution, body composition, liver biochemical indices, as well as digestive enzymes activities of juvenile Chinese crucian carp. Six isolipidic and isoenergetic diets were formulated containing 30.18%, 33.13%, 36.16%, 39.34%, 42.32%, and 45.46%, respectively. A total of 540 juvenile Chinese crucian carp with the average initial weight of (3.10 ± 0.01) g were randomly distributed into six groups with three replicates per group, containing 30 juvenile Chinese crucian carp per replicate, which were fed for eight weeks. The results indicated that with the increase of dietary protein level, the weight gain rate (WGR), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), the whole body protein content (WBPC), the hepatic glutamic-pyruvic transaminase (GPT), and intestinal trypsin (TPS) activities of fish in 36.16% group were significantly higher than those in other groups (P<0.05). The hepatic total cholesterol (HTC) and triglyceride (TG) content of fish in 30.18% group were remarkably higher than those in other groups except for 33.13% group. Based on the quadratic regression analysis of theSGR, PER, and dietary protein levels, it was revealed that the rate of optimal dietary protein for Chinese crucian carp ranges from 35.29% to 37.07% under the experimental condition.
To assess the effects of dietary supplementation with glutathione (GSH) on tissue GSH levels, immunity, and antioxidant capacity of juvenile yellow catfish (Pelteobagrus fulvidraco), a total of 800 yellow catfish with a mean body weight of (1.32±0.01) g were considered and randomly divided into 5 groups with 4 replicates per each group and 40 fish per each replicate as well. During 56d, the fish were fed by a basal diet and four test diets, which supplemented with 100, 300, 500, and 700 mg/kg of reduced GSH, respectively. The results indicated that, except for 100 mg/kg group, supplementation with GSH significantly increased the GSH content in liver and serum of yellow catfish (P<0.05). When GSH level was 300 mg/kg or higher, GSH content in liver and serum was in a stable state. With the increase of glutathione level, the immunity and antioxidant indices were initially increased, and then decreased. The lysozyme and alkaline phosphatase activities in 300 and 500 mg/kg groups, immunoglobulin M (IgM) and complement component 4 (C4) contents in 300 mg/kg group, and acid phosphatase activity in 500 mg/kg group markedly increased, compared with the control group (P<0.05). There were no significant differences (P>0.05) in complement component 3 (C3) and nitric oxide contents among all groups. Compared with the control and 700 mg/kg groups, the liver superoxide dismutase, catalase and glutathione peroxidase activities, total antioxidant capacity and the serum superoxide dismutase, as well as glutathione peroxidase activities in 300 mg/kg group were significantly higher (P<0.05), while the serum malondialdehyde content in that group was considerably lower (P<0.05). Under ammonia-nitrogen stress for 96h, compared with the control group, the liver and serum superoxide dismutase, catalase, and glutathione peroxidase activities in 300 mg/kg group were significantly greater (P<0.05), however, the serum malondialdehyde content in the mentioned group was significantly lower (P<0.05). In conclusion, dietary supplementation with GSH could enhance the tissue GSH level, immunity and antioxidant capacity of juvenile yellow catfish, and the effective range of this enhancement was 300 to 500 mg/kg as well.
An experiment was conducted to investigate the effects of replacing fish meal (FM) and soybean meal (SBM) by fermented soybean meal (FSBM) on growth performance, serum biochemical indices, and immune genes in giant river prawn, Macrobrachium rosenbergii, and to find a suitable proportion of FSBM to replace FM in diets. Five isonitrogenous and isoenergetic diets were formulated for giant river prawn, among which a basal diet (T0) containing 30% FM and 18% SBM was treated as the control group, and the FM and SBM (2﹕1) in the basal diets replaced by 2% (T2), 5% (T5), 8% (T8) and 15% (T15) of FSBM respectively were treated as experimental diets. Giant river prawns with initial average body weight of (0.17±0.02) g were cultured for 64 days in indoor net cages at a cement tank. Results showed that with increasing FSBM supplemental level, the growth rate and specific growth rate increased firstly and then decreased, and the highest value was found in group T8. Serum superoxide dismutase activity and malondialdehyde content firstly increased and then decreased. MDA of all experimental groups was higher than that of the control group. Serum aspartate transaminase, alanine aminotransferase activity and total protein content had decreasing trend followed by an increasing trend, and the values in all experimental groups were lower than the control group. Gills Toll receptor mRNA and NF-κB mRNA expression levels and hepatopancreas heat shock protein mRNA relative expression levels in group T15 were the highest among all groups. All these results indicated that the replacement of FM and SBM with FSBM would affect growth, antioxidant ability and immunity, and the optimum amount of FSBM was 8% in the diets in this experiment.
To evaluate the effects of different dietary protein levels on the growth performance, non-specific immunity and protein metabolism enzymes of Rhynchocypris lagowskii Dybowski, diets with 24.98%, 30.02%, 34.99%, 40.01% and 44.98% protein formulated with fish meal, soybean meal, rapeseed meal and cottonseed meal were fed to Rhynchocypris lagowskii Dybowski (6.98±0.01) g for 8 weeks in this study. After the feeding trial, a national standard method was used for determining muscle nutrients, and kits were used to measure serum alkaline acid enzyme (AKP), acid phosphatase (ACP), superoxide dismutase (SOD) and lysozyme (LZM) activity. The results showed that, with the increase in protein levels, final mean body weight, weight gain rate and specific growth rate firstly increased with increasing protein levels, and then decreased. When the protein levels were 34.99% and 40.01%, the final mean body weight, weight gain rate and specific growth rate were significantly higher than that in the groups with 24.98% level (P<0.05). With increasing protein levels in diets, feed and protein efficiencies ofRhynchocypris lagowskii Dybowski firstly increased, and then decreased. Feed and protein efficiencies in 40.01% groups were significantly higher than those in 24.98% groups (P<0.05), but there was no significant difference among groups with 30.02%, 34.99%, and 40.01% protein levels (P>0.05). According to the polynomial regression analysis, the specific growth rate ofRhynchocypris lagowskii Dybowski was the highest when protein level was at 35.89%, and the feed efficiency was the highest when the protein level was at 36.11%. The content of crude protein in muscles increased first, and then decreased with increasing protein levels in diets. Among them, the crude protein content in muscles of 40.01% group was significantly higher than that in the other four groups (P<0.05). However, the crude fat content in muscles decreased first, and then increased with increasing protein levels. The crude fat content in 40.01% group is significantly lower than that in the 24.98%, 30.02%, and 34.99% groups (P<0.05), but the 44.98% group showed no significant difference from other groups (P>0.05). The activities of alkaline phosphatase (AKP), acid phosphatase (ACP), superoxide dismutase (SOD) and lysozyme (LZM) in hepatopancreas increased first, and then decreased with increasing protein levels. The activities of AKP, ACP, SOD, and LZM in the 40.01% group were significantly higher than those in the other four groups (P<0.05). The RNA and RNA/DNA ratios in muscles increased firstly, and then decreased with increasing protein levels. Among them, the RNA content and RNA/DNA in 40.01% group were significantly higher than those in the other four groups (P<0.05). According to the polynomial regression analysis, the RNA content in white muscle was highest when the protein level was 36.10%, and the RNA/DNA ratio was highest in white muscle when the protein level was 35.91%. Therefore, in the formulated diets, the most suitable protein level is 34.99% to 40.01%.
Swimming crab (Portunus trituberculatus) is an important mariculture crab, and the light color of the pond-reared crabs may be related to low level of dietary astaxanthin. This study was designed to investigate the effects of dietary astaxanthin on ovarian development, coloration, antioxidant capacity, immune performance and biochemical composition of female P. trituberculatus. Haematococcus pluvialis powder was used as natural astaxanthin source to formulate four experimental diets with different astaxanthin levels (0, 26.60, 41.62, and 81.37 mg/kg, defined as Diet 1#—4#). The four experimental diets were fed to female P. trituberculatus for 45 days during the ovarian development; therefore, there were four treatments in this study. The results showed as follows: (1) Dietary astaxanthin had no significant effects on gonadosomatic index (GSI) and hepatosomatic index (HSI). (2) Total carotenoids content, redness (a*) and yellowness (b*) values of hepatopancreas, ovaries and carapace increased significantly with increasing dietary astaxanthin, while the lightness (L*) values of these tissues showed a decreasing trend (P<0.05). (3) For antioxidant indices, the activities of super oxide dismutase (SOD) and peroxidase (POD) in treatments (Diet 2#—4#) with supplementation of astaxanthin were significantly lower than those in Diet 1# treatment without supplementation of astaxanthin. The activities of total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) in hemolymph as well as the SOD, T-AOC in hepatopancreas increased significantly with elevated dietary astaxanthin, while a decreasing trend was found for the malondialdehyde (MDA) content in the hemolymph and hepatopancreas. (4) For the immune indices, Diet 4# treatment had the highest activity of acid phosphatase (ACP) in hemolymph and hepatopancreas, while Diet 1# treatment had the significantly higher hemolymph hemocyanin (Hc) content than other treatments (P<0.05). (5) As for the biochemical composition, the increasing trend was found on the contents of total lipids and total carbohydrate in the muscle and hepatopancreas as well as ovarian lipids with increasing dietary astaxanthin, while Diet 2# treatment had the highest total carbohydrate content in the ovaries among the four treatments (P<0.05). In conclusion, dietary supplementation of astaxanthin had no significant effect on ovarian development ofP. trituberculatus, but could improve the coloration, antioxidant capacity and the contents of total lipids and total carbohydrate in edible tissues. These results suggest the appropriate level of astaxanthin in fattening diet was approximately 50 mg/kg for adult female P. trituberculatus.
Myeloid differentiation factor 88 (MYD88) is a key adapter protein in Toll-like receptor (TLR) signaling, which plays significant role on the innate and adaptive immunity. In this study, a myd88 gene from lamprey (Lampetra japonica) was obtained. The ORF of myd88 is 852 bp in length, encoding a polypeptide of 283 amino acids. The theoretical molecular weight of lamprey Myd88 is 32.432 kD with a theoretical isoelectric point of 6.25. Lamprey Myd88 was predicted to have no signal peptide. Multiple protein sequence alignment revealed highly conserved death domain in N-terminal, and Box1, Box2, and Box3 in the C-terminal TIR domain, which indicated that lamprey Myd88 is homologous with the MYD88 in other species. Quantitative real-time PCR analysis showed lamprey myd88 gene was extensively expressed in all detected tissues. The highest expression level was observed in gill, which was followed by marrow and kidney. Under in vivo stimulation by lipopolysaccharide (LPS), the expression of myd88 significantly increased in leukocytes, followed by gill, which implicated its role in the defense of L. Japonica against bacteria. Furthermore, increasing expressions of downstream proteins in Myd88-dependent TLR signaling pathway, including Irak1, Traf6, Ikkβ, and Nfkb, were detected in the tested tissues stimulated with LPS. These results suggested that a conserved Myd88-dependent TLR signaling pathway was found in the lamprey, which play a fundamental role on the exploration of the origin and evolution of the signaling pathway in immune response in future.
In this study, microsatellite markers were used to assess the genetic structure and genetic diversity of the second generation of Tegillarca granosa. In addition, the correlation of these markers with growth-related traits was assessed to explore their potential use for marker-assisted breeding. Genome-wide identification and structural analysis herein led to detect 59 alleles through 18 pairs of primers. Among these, the average values of alleles (Na) in the families of F19, F21, and F22 were 2.500, 2.722, and 2.722, respectively. The average observed heterozygosity (Ho) was 0.446, 0.510, and 0.628; the average expected heterozygosity (He) was 0.394, 0.433, and 0.464, respectively. In addition, the corresponding values of polymorphism information content (PIC) were 0.346, 0.379, and 0.403, respectively. Correlation analyses of these polymorphic markers and growth traits revealed significant association of three loci with shell height, shell length, shell width, and total weight. Specifically, genotype BB of Teg-30 in F19 was remarkably associated with shell height and total weight, while genotype BB of Teg-03 and genotype BC of Teg-20 in F21 showed a significant correlation with the shell height, shell length, shell width, and total weight. As a result, the growth-related markers, identified in the present study, may provide precious genetic information and novel insights for molecular marker-assisted breeding of T. granosa.
LBH (limb-bud and heart) is a novel high-conserved transcription cofactor in vertebrates involved in embryonic development and pathogenesis of some human disease. We screened the lbh-b gene that was abundantly expressed in the pituitary of gibel carp, and cloned the lbh-b (Cglbh-b) cDNA sequence of lbh gene family from gibel carp cDNA library by RACE-PCR. The full-length of Cglbh-b cDNA was 1526 bp with a 549 bp long open reading frame (ORF) coding a 182 amino acid protein. Bioinformatics analysis showed that CgLbh-b protein shared high homology (>68%) with other vertebrate LBH and is one of intrinsic disordered proteins.Cglbh-b was abundantly expressed in pituitary, telencephalon, ovary and eye of adult gibel carp. The expression of Cglbh-b in female pituitaries was 4.66 times higher than that in male pituitaries, and Cglbh-b in pituitary was up-regulated during the process of oocyte maturation. During the early embryonic development, maternal mRNA of Cglbh-b was detected in embryos from 4-cells stage to gastrula stage, and its transcripts were synthesized at bud stage. The results of whole mount in situ hybridization showed that Cglbh-b was distributed on the brain and eyes of embryos from 2 days post fertilization (dpf) to 3dpf. These results suggest that Cglbh-b may play important roles in brain and retina development, and reproductive regulation in oocyte maturation of gibel carp.
This study was conducted to explore the effects of berberine on the mRNA expression of G protein coupled receptors 43 (GPR43) and the lipid metabolism performance of blunt snout bream fed with high-fat diet. GPR43 in blunt snout bream was cloned and sequenced with a RACE assays. The effects of berberine on GPR43 mRNA expression in tissues were also investigated. The obtained full-length nucleotide sequence covers 2026 bp, which has an open reading frame of 981 bp, and translates a total of 326 amino acids. Moreover, GPR43 mRNAs were detected in different tissues of blunt snout bream. In blunt snout bream, the expression of GPR43 in intestine, hepatopancreas, gill and white muscle were the highest. 320 fish (80.00±0.90) g were randomly divided into four trial groups (each has four replicates) and fed with 4 diets (normal diet, normal diet with 50 mg/kg berberine, high-fat diet, and high-fat diet with 50 mg/kg berberine, among which normal diet has 5% lipid and high-fat diet has 10% lipid), respectively. The expression of GPR43 mRNA in the high-fat diet group decreased compared with control group, while it significantly increased (P<0.05) after adding in berberine. Compared with the control group, the contents of free fatty acids (FFA), triglycerides (TG), cholesterol (CHO), and mRNA expressions of Cytokinins protein kinase (p38), and Peroxidase value-added factor (PPARγ) all increased (P<0.05) in the high-fat group, but a dramatic decrease (P<0.05) happened after adding in berberine. The same result was found on the composition of Polyunsaturated fatty acids (PUFA) in hepatopancreas and muscle tissues. A completely inverse variation was presented on the mRNA expressions of Carnitine palm acyltransferaseⅠ (CPTⅠ), Peroxidase value-added factor (PPARα&β) and AMP dependent protein kinase (AMPK), as well as on the compositions of Saturated fatty acids (SFA) and Monounsaturated fatty acids (MUFA) in both tissues. Nevertheless, the difference between berberine supplemental normal diet group and control group was out of regular pattern. so further work is still needed to explore the role of berberine in normal circumstances. Overall, the results showed the supplement of berberine could slow down lipid deposition in hepatopancreas, and restore lipid homeostasis which has been damaged by continuous high-fat diet feeding.
This study attempted to theoretically support and comprehensively perceive genetic diversity and reproduction of Corbicula fluminea from the Laodao River in Liuyang city was investigated. Partial sequences of the cytochrome oxidase c subunit 1 (COⅠ) of mitochondrial genes were utilized to evaluate the genetic diversity, and reproductive characteristics were observed by gonadal histology and sperm morphology using light microscopy. Among examined 40 individuals, only 4 haplotypes and 17 variable sites were detected in the partial sequences of the COⅠ, with an average haplotype diversity, nucleotide diversity, and number of variable sites equal to 0.664±0.042, 0.014±0.006, and 8.595, respectively. Hermaphrodite was a predominant reproduction in the population studied, and the hybrid hermaphrodite-sex ratio was 6﹕3﹕1. Furthermore, there were two types of reproductive follicles in hermaphroditic individuals, including sperm and egg cells in the same and in different follicular cells. The observation of sperm morphology revealed that biflagellate spermatozoa were discovered in both hermaphrodite (n=23) and male (n=8) cases. The results also showed that Corbicula fluminea samples from the Laodao River of Liuyang city contained a relatively low genetic diversity, but with multiple reproduction modes, and the predominant mode was androgenesis. This study attempted to present significant biological reproduction information required for Corbicula fluminea protection in China.
This study investigated cell ultrastructure of Rhopilema esculentum during embryogesis and metamorphosis into a polyp using scanning and transmission electron microscopy combined with protargol staining method. Our study showed that (1) Cell cleavage was almost equal from fertilized egg to gastrula. All divided cells were similar in morphology, and cell junctions were observed among adjacent cells; (2) Vacuoles in cell were firstly observed at ectoderm of early planula, and became bigger as developing to 4-tentacle polyp, while the vacuoles of entoderm were firstly found at 4-tentacle polyp stage. The suspected apoptotic body were observed at scyphostoma and polyp stages; (3) Immature cnidocytes were firstly observed in ectodermal area closed to mesoglea ectoderm at early planula stage, moved to outside, located at outermost layer, and matured at polyp stage; (4) Cilium was observed at early planula stage, gradually degraded, and completely disappeared at polyp stage; (5) Lots of yolk bodies with dark stain were observed at all developmental stages, and the phagocytosis of ectodermal cell of planula was firstly observed. These phenomena suggest that planulae of R. esculentum were both planktotrophic and lecithotrophic, which would provide the scientific basis for illuminating the developmental pattern of embryonic and metamorphosis of cnidarians.
In the present study, the effects of isoleucine on the mammalian target of rapamycin signaling (mTOR) pathway and nitrogen metabolism were investigated through Intraventricular (ICV) administration in Chinese perch (Siniperca chuatsi). In one hand, the ammonia excretion significantly increased, and mRNA levels of nitrogen metabolism genes involving glutamate dehydrogenase (GDH), glutamic oxaloacetic transaminase (GOT), and adenosine monophosphate deaminase (AMPD) remarkably increased after ICV injection of isoleucine as well (P<0.05). On the other hand, the results showed that blood glucose levels markedly decreased at 0.5 h post-injection. The expression of liver ribosomal protein S6 was also notably enhanced, demonstrating that mTOR signaling pathway was activated. The results also indicated that isoleucine could activate the mTOR signaling pathway, mediate amino acid metabolism, and enhance ammonia-N excretion via nitrogen metabolism genes in Chinese perch.
The fermented soybean meal (FSM) was used as a replacement of fish meal (FM) in a practical diet with 45% protein and 10% lipid, to investigate its effects on the growth, intestinal histology, and the structure of intestinal dominant bacteria in juvenile large yellow croaker. FM was replaced by 0, 15%, 30%, 45%, 60% and 75% of FSM (FSM0, FSM15, FSM30, FSM45, FSM60 and FSM75), respectively. The fish of 10.49 ± 0.03 g was hand-fed daily to satiation twice for 56 days. Results showed that the survival rate (SR) was not significantly affected with all the diets (P>0.05), but in groups FSM60 and FSM75, theSR had a downward trend. In comparison with FM0, the weight gain rate (WGR) and specific growth rate (SGR) in FSM60 and FSM 75 decreased significantly (P<0.05), while the feed conversion rate (FCR) increased significantly (P<0.05). Feed intake (FI) increased significantly in FSM60 and FSM75 (P<0.05), compared with that in FSM0, FSM15, FSM30 and FSM45. The observed intestinal histology results showed that Mucosa thickness, Mucosafold height, Laminapropria width and Gobletcell quantity were not significantly affected in all the diets (P>0.05). Sequencing results of intestinal contents from Illumina-MiSeq high-throughput sequencing technology showed that the index of Chao1, Shannon, Simpson and Good coverage in FSM0 (TC the control), FSM45 (TB the best group in growth) and FSM75 (TW the worst group in growth) were not significantly affected (P>0.05).Firmicutes group totally dominated the bacterial communities in juvenile large yellow croaker. Paenibacillus genus was the most dominant bacteria in microbial ecosystem. Bacterial composition had certain effect on the growth of large yellow croaker: compared with TW group, the species richness of Paenibacillus and Alkaliphilus increased significantly in TB group and TC group (P<0.05). However, compared with TW group, the species richness ofEnhydrobacter in TB and Paracoccus in TC decreased significantly (P<0.05). These results suggested that the optimal dietary protein level was about 45% without negtive effects on the growth, intestinal histology, and the structure of intestinal dominant bacteria in juvenile large yellow croaker.
It has been discovered that low-head dam could impact local habitat conditions, and alter fish assemblages in streams. However, how fish assemblages respond to the size and function of low-head dams is still not clear. Based on the data collected from 15 impounding segments upstream and 15 plunging areas downstream of low-head dams in the Wannan Mountains at July and November 2016, respectively, we examined how habitat factors and fish assemblages varied seasonally, and the differences in their response to dam size and function. Furtherly, after classifying the collected samples into two types (indigenous species and native-invasive species), we determined whether the indigenous fishes and native-invasive fishes were different in their responses to dam disturbance. A total of 24 fish species representing four orders and ten families were collected, including 11 indigenous species and 13 native-invasive species. Although fish assemblages in the plunging areas did not vary seasonally, the assemblages in the impounding areas was significantly different between July and November, where fishes were more abundant in November than in July. Only the assemblage structure of native-invasive fishes in the plunging areas was influenced by dam size. However, both native fish assemblages in the impounding areas and native-invasive fish assemblages in the plunging areas showed difference in their response to the between-dam-function, suggesting that dam function was more important in impacting fish assemblages than dam size. Compared to those associated with the impounding dams, the irrigating dams had less Zacco platypus but more Cobitis sinensis and Ctenogobius spp. in the impounding areas, and more Rhodeus ocellatus and Misgurnus anguillicaudatus in the plunging areas. In addition, the response of the whole fish assemblages (including both indigenous and native-invasive species) to dam disturbance was similar to the indigenous fish assemblages, instead of the native-invasive fish assemblages. Our results suggest that, in this study area, dam function was more important in influencing local fish assemblages than dam size. Due to their potential differences in response to dam disturbance for the indigenous species and native-invasive species, it is necessary for us to distinguish these two types of species when we assess how anthropogenic activities affect fish diversity in streams.
Many efforts have been devoted to developing, constructing and refining fishways or fish passage facilities to facilitate the target fish species to pass barriers in fluvial systems. Once dominated by an engineering-focused approach, fishways science nowadays involves a wide range of disciplines from fish behaviour to socioeconomics, and to complex modeling of passage prioritization options in river networks. Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovations. After the completion of fishways construction, corresponding management systems usually need to be improved as well. In the current study, we first reviewed international fishways adaptive management systems (e.g., aspects of development, construction, and management) from 1991 to 2017 reporting on " fishway”, " fish passage”, " fish” and " dam”. The functions of fishways gradually transferred from conservation of economic stocks to overall biodiversity conservation, from facilitating upwards to both upwards and downwards passages, from developing a single project to considering the entire river basin, from fish passing function to habitats restorations as well, and from pure engineering construction to considering adaptive management. Finally, we discussed adaptive management systems and management prospects of fishways for China.
The lower Mississippi River (LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to " notch” wing-dike structures that close secondary (side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer (rkm) 628 (Louisiana-Mississippi, U.S.A.) upstream to rkm 1504 (Missouri-Kentucky, U.S.A.). Four secondary channels were termed " permanent” (i.e., with notched dikes) while three secondary channels were termed " temporary” (i.e., without notched dikes). Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from 1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad (Dorosoma cepedianum), threadfin shad (D. petenense), and white bass (Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish (Ictalurus furcatus), flathead catfish (Pylodictis olivaris), and freshwater drum (Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However, temporary secondary channels also contain unique fish species, and also appear to be important sites of riverine primary production. Restoration strategies should consider a balance of both secondary channel types, which should support the greatest biodiversity for the LMR ecosystem.
This study examined anesthetic behaviors of Schizothorax o’connori Llord in two size ranges as induced by MS-222, to acquire useful information on anesthesia of said highland fish species in out-of-water activities (surgery, labeling, measurement, etc.). Test results indicated that for both large (25.0±1.5) cm and small-sized (14.8±2.3) cm specimens, respiration rates showed no significant change in anesthetic stages I to III, and only begun to significantly decline after entering stage IV. The effective concentrations of MS-222 were 150—180 mg/L and 150 mg/L for two sizes, respectively. The 150—180 mg/L caused large specimens to enter anesthetic stage IV within 5min, and recovered within 5min; the 150 mg/L caused small specimens to enter stage IV within 5min, and recovered within 7min; both doses ensured a 100% survival rate after immersion for 20min. For large specimens anesthetized at 180 mg/L for 5min and exposed to air for 0—15min, there was no significant difference in recovery times (P>0.05); for small specimens anesthetized at 150 mg/L for 5min and exposed to air for 0—15min, there were significant differences in recovery (P<0.05).
This study is based on monthly sampling (from April 2013 to April 2015) of 18 fish species representing three families. Samples were obtained using benthic fyke-nets, block nets, and multi-mesh gillnets in Lake Kuilei, a shallow lake of the Yangtze River basin, China (N 31º24', E 120º51'). Using ordinary least-squares linear regression, length-weight relationships of these fish species were estimated, with equations for 3 species reported for the first time. The maximum total length records of the 15 species exceeded those reported in FishBase. This paper provides new LWR equations for these species to be included in FishBase.
The ecological risk of a Microcystis bloom was evaluated on the basis of the ecotoxicological risk assessment method. The effects of Microcystis bloom on benthic fauna, zooplankton, fish, and submerged macrophytes were assessed by using exposures of acute and chronic and findings reported by previous studiesThe algal cell densities were calculated using toxicity percentile rank (TPR) method, and aquatic ecological risk assessment for Microcystis bloom was performed using risk quotient approach. The criteria required for acute and chronic ecological risk assessment of Microcystis bloom were defined based on the algal cell density, algal bloom coverage in lake, as well as duration of algae blooms. The ecological risk of an acute was classified as low-, moderate-, and high- levels. A Microcystis bloom with cell density less than 3.4×106 cells/L was defined as low risk-level, with cell density at the range of 3.4×106—3.4×107 cells/L was denoted as moderate-risk level, and with cell density higher than 3.4×107 cells/L was defined as high-risk level. Similarly, an ecological risk of a chronic toxicity was also classified as low-, moderate-, and high-levels of risk. The Microcystis bloom with cell density less than 1.1×106 cells/L was classified as low risk, cell density between 1.1×106—1.1×107 cells/L was classified as moderate risk, the cell density greater than 1.1×107 cells/L was classified as high risk. In practical applications, cell density, algal bloom coverage, and duration of algae blooms are essential factors to formulate a robust ecological risk assessment strategy for Microcystis bloom in Erhai Lake. In presence of moderate-risk level, early warning of Microcystis bloom should be alarmed, and improvement of water quality or implementation of biological control should be carried out. Under the high risk level, emergent removal or control of algal bloom should be undertaken as well.
To investigate the influence of artificial substrates (AS) on the growth performance of fish in pond poly-culture systems, a feeding experiment was conducted in six individual earthen ponds, which were divided into two groups. The ponds with AS in the water were labeled as the " AS group” and that without the use of AS were labeled as the " control group” (three ponds per group). A total of 3867 common carp [Cyprinus carpio, (310±11) g], being artificial-feeds feeding fish, and 370 bighead carp (Aristichthys nobilis) and silver carp [Hypophthalmichthys molitrix, (810±15) g], being plankton filter feeding fish, were divided into six groups and cultured in the ponds respectively. The common carp in each pond were fed with commercial particle feeds three times a day and the feeding period was 62 days. Water quality, concentration of plankton and the bacterial community presenting in the water and sediment were monitored during the experiment. At the end of the experiment, all fish were harvested and the growth of the fish and feed efficiency ratio were determined. Results showed that the weight gain rate and feed efficiency ratio of common carp in AS group was significantly higher than that of the control group. Final body weights of bighead carp and silver carp in the AS group were significantly lower than that of the controls. Water transparency and diversity indices of the bacterial community in the AS group were significantly higher than that of the control (P<0.05) and the concentration of plankton in the AS group was lower than that of the control. Results showed that the application of AS in poly-culture ponds was beneficial for the growth of common carp, being artificial-feeds feeding fish, while it was not beneficial for the growth of bighead carp and silver carp, being plankton filter feeding fish.
To examine the cause of the disease of Sciaenop socellatus of cultured pond in Zhuhai, Guangdong Province from June to October, the epidemiological investigation, the symptom observation, the pathogenic detection, and the pathology detection were used. These results showed that the disease had obvious infectious. The anatomy examination revealed the anemia of the gill filament, swollen spleen and kidney with hemorrhagic spots, and no observed large number of parasites by microscopy. Meanwhile, no pathogenic bacteria were isolated from the liver, spleen, kidney and intestine of the diseased fish. A large number of swelling cells were observed in pathological sections of liver, spleen and kidney of diseased fish. The 570 bp fragment was amplified by PCR using the specific primers of OIE. MCP sequence alignment showed that the amplification of the gene sequence had 99.2% of homology with gene sequence of RSIV. The comprehensive results showed that the cause of the disease of the Sciaenop socellatus is infected by the iridovirus of Megalocytivirus genus.
In order to investigate the diversity of Pseudo-nitzschia species in China’s coast and their ability in producing neurotoxin domoic acid (DA), a total of fifteen monoclonal Pseudo-nitzschia strains were isolated and established. Using a liquid chromatography tandem-mass spectrometry (LC-MS/MS) technique, DA was accordingly detected from ten monoclonal strains. Based on the morphology observed by using a light microscope (LM), a transmission electron microscope (TEM), as well as molecular analysis inferred from an internal transcribed spacer region, these fifteen strains were precisely identified which belonged to three different species involving, P. cuspidata (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, and P. fraudulenta(Cleve) Hasle. In addition, three out of eleven established P. cuspidata strains were nontoxic, while other eight cases were toxic with the DA abundance rate of 0.4—5.5 fg/cell. Also, one P. pseudodelicatissima strain was nontoxic, while DA production rate of 1 fg/cell was detected in another strain. Besides, no DA was tested in the two P. fraudulenta strains. Several strains were selected and their DA productions were induced by the available Artemia salina. As a result, it was shown that the ability of DA production decreased in P. cuspidate (MC4049) and P. pseudodelicatissima (MC3015) strains, from 2 and 1 to 0.2 and 0.4 fg/cell, respectively. However, the ability of DA production in P. fraudulenta(MC4074) strain swiftly increased, from an undetected level to 17.5 fg/cell. The results achieved in this study enrich the diversity of toxic Pseudo-nitzschiaspecies in China’s coast, and may establish strong research basis for conducting further studies.
Metsulfuron-methyl is one of the sulfonylurea herbicides, which have been widely used throughout the world because of its significant advantages and safety. However, long-term use of Metsulfuron-methyl will impose a threat to aquatic ecosystems. Algae are frequently the major primary producers in aquatic ecosystems, often as an indicator to study water pollutants. In this study, dominant species of cyanobacteria (Microcystis aeruginosa PCC7806) were selected to deeply perceive the effect of Metsulfuron-methyl on the growth and photosynthetic of Microcystis aeruginosa. The achieved results show that the growth of M. aeruginosa PCC7806 is significantly inhibited when the concentration of Metsulfuron-methyl exceeds 80 mg/L. The EC50 of the growth of M. aeruginosa PCC7806 is 81.998 mg/L by regression and Probit analysis. The results of cytochrome studies demonstrate that the content of chlorophyll a and carotenoids in unit cell of the treatment group on the 6th day is lower than that of in the control group, and when the concentration of Metsulfuron-methyl is 80 mg/L, the carotenoids content is remarkably lower than that of in the control group. The results of kinetics of chlorophyll fluorescence showed that the energy (ET0/RC) captured by the unit reaction center for electron transport (φE0) is used for quantum yield of photosynthetic of electron transport, which is extraordinary suppressed on the 6th day of the experiment. The results of chlorophyll fluorescence induction and cytochrome analysis show that Metsulfuron-methyl could negatively affect the electronic properties of the electron acceptor in the photosynthetic reaction center. In summary, Metsulfuron-methyl may act on the electron acceptor side of the photosynthetic response center, thereby likely affecting the photosynthetic system of Microcystis aeruginosa.