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Abstract:By using the GNOME model of oil spillage, the drift trajectory and diffusion distribution of the “Century Light” oil spill were simulated. First, the FVCOM hydrodynamic model was used to simulate the tidal field, which was broadly consistent with the results of the tide tables. The wind field was determined by using the Climate Forecast System Reanalysis Data (CFSR) of the National Center for Environmental Prediction (NCEP). The GNOME oil spill model was used for numerical simulation, and Tyson’s method was used for the analysis of the contaminated area. The “minimum regret” trajectory and the best forecast region were obtained through numerical simulation. The comparison of the simulation results after 21 hours with the MODIS remote sensing monitoring data showed that the drift position was basically consistent. This paper describes the assessment criteria for various fishery resources and methods for determining marine ecological damage and loss compensation assessment. Combining the simulation results with the trawl survey data, the direct economic loss of swimming animals was calculated to be 61000 yuan, with the direct loss of fishery resources, within 4 days, reaching a value of 511900 yuan. The oil loss from the “Century Light” event reached a value of 2112600 yuan within 4 days. In this paper, the method of numerical simulation was related to the assessment of fishery resources, and the loss of fishery resources was estimated without on-site observation. The GNOME oil spill model can be applied to similar oil spill trajectories and for rapid prediction of flooding, to provide a method and reference for emergency response to oil spill accidents. The combination of numerical simulation of oil spills and on-site observations will be an important reference method for new ideas in future calculations of fishery resource losses and fishing losses, leading to more comprehensive and scientific handling of oil spills.

Abstract:Ocean acidification caused by increasing amounts of carbon dioxide has a great impact on marine organisms, especially calcified coccolithophores. However, culture experiments examining the response of coccolithophores to elevated CO2 pa have mostly been based on investigations of a single strain and have yielded differences and even contradictory results from experiments between and even within species. Here, four strains of the coccolithophores, which contained naked and calcifying strains, were investigated simultaneously for the first time. Four carbon dioxide concentration gradients (400 µatm, 750 µatm, 1000 µatm, and 2000 µatm) were set up to systematically study the effects of ocean acidification on growth, photosynthesis, nitrogen source absorption, element composition and calcification efficiency of four coccolithophore species by batch aeration culture. The results did not show a uniform response from the different strains to elevated CO2 concentrations up to 2000 µatm, and the naked strain Emiliania huxleyi (N-E) was seriously suppressed, which was in sharp contrast to the positive response of the other three algae to the different levels. On the other hand, photosynthetic parameters Fv/Fm, Y(II) and pigment show overall downward trend for all four strains, and calcification efficiency of C-E and C-G decrease 35.4% and 68.9% respectively, on the seventh day. In addition, the four coccolithophore strains of particulate organic nitrogen production show an increasing trend and the resulting POC/PON and PIC/POC declin. We determined that the responses of coccolithophores to ocean acidification are specific, and this variation may cause changes to biodiversity and other ecosystem processes in the ocean of the future.

Abstract:Laminaria hyperborea is an economically and ecologically important kelp. It can grow lushly in the subtidal zone and from the seaweed forest, playing a significant ecological function. In this study, the absorption rates of nitrogen and phosphorus of L. hyperborea was determined at different temperatures (5℃, 9℃, 13℃, 17℃), as well as relative growth rate (RGR) and accumulation of selected heavy metal ions (arsenic ions As5+, cadmium ions Cd2+, lead ions Pb2+), aiming to evaluate whether L. hyperborea is a potentially feasible candidate species for marine bioremediation. The main results are as follows: (1) the experimental specimens illustrated maximum absorption rates of nitrogen and phosphorus at 9℃~13℃ after 72 h. The maximum absorption rates of phosphorus, ammonia nitrogen and nitrogen nitrate were 95%~98%, 96% and 42% respectively, indicating that the removal of nitrogen nitrate, ammonia nitrogen, and phosphorus by L. hyperborea from seawater is significant. (2) The total arsenic ions content accumulated in the L. hyperborea was 168.33 mg/kg, there was no significant difference between the surface (55%) and inner (45%) of the algae; the relative growth rate was –0.92%/d when L. hyperborea were treated with arsenic ions for 6 days. The total cadmium ions content accumulated in L. hyperborea was 15 mg/kg, and the surface content (91%) was significantly higher compared to the inner content (9%); the relative growth rate of those individuals who were treated with Cd2+ enriched solution for 6 days was 5.78%/d (lower than the control). The total lead ion content accumulated in the L. hyperborea was 320 mg/kg. The surface concentration (96.5%) was significantly higher compared to that of the inner concentration (3.5%) of the algae; the relative growth rate of those individuals who were treated in Pb2+ enriched solution for 6 days was 6.73%/d, which had no significant difference with control condition. The results suggested L. hyperborea could be an ideal candidate in marine bioremediation.

Abstract:Heavy metal contamination of the natural environment has always been a great concern, because of toxicity and non-biodegradability of the metals. Copper (Cu) is an abundant trace element found in a variety of rocks and minerals and has received much attention due to its widespread use, persistence in nature, tendency to accumulate in and toxicity to aquatic organisms. There are many documented physiological effects of waterborne Cu2+ exposure in a variety of shellfish species, but further research is needed to explain the relationship between Cu2+ and shellfish species. To study the toxicological effects of Cu2+ on mussel Mytilus coruscus, juvenile M. coruscus were exposed to aqueous solutions of Cu2+. Ninety-six-hour acute toxicity effect experiments and 7 days stress experiments were carried out. Biomarkers including superoxide dismutase (SOD), catalase (CAT), lipid peroxidation (LPO), and metallothioneins (MT) in gill and visceral mass were determined after seven days of exposure. Integrated biomarker response (IBR) was calculated by combining multiple biomarkers into a single value in order to assess the responses of different tissues. The acute toxicity experiments showed 1.55 mg/L to be the 96 h median lethal concentration in juvenile M. coruscus. The 7 days stress experimental results showed that the activity of biomarkers were inhibited by all test concentrations and each index hadits own variation trend.Biomarkers SOD and CAT showed activity in gill and visceral mass, MT content in the gill firstly increased and then tended to decrease later, while the MT content in visceral mass and MDA content in gill and visceral mass exhibited an upward tendency. IBR values exhibited an increase at first then tended to decrease later, the IBR value in the visceral mass was higher than that in the gill. Changes of biomarkers’ activity were related to different exposure concentrations. IBR analysis allowed good discrimination between the different exposure concentrations and might be a useful tool for the quantification of various biomarker responses induced by toxic chemicals.

Abstract:In this study, computational fluid dynamics (CFD) technology was used to study the flow patterns around porous square artificial reefs with different disposal spaces. The aim was to increase our knowledge base of the fish harvesting principles of artificial reefs and the deployment and layout of the artificial reefs in the construction of marine pastures. Four kinds of disposal spaces were used in the study; they were 0.5, 1.0, 1.5, and 2.0 times the height of the reef. Based on the computer numerical simulation technology, the process of water flowing past the two reefs at a speed of 0.8 m/s was simulated, and the flow around the reef was observed. The results show that there were obvious characteristics of slow flow areas, back eddy current areas, upwelling areas, and dead water areas inside and around the porous square artificial reef. The ratio of the maximum upwelling velocity to the inflow velocity of the porous square artificial reef was about 0.95 times. The ratio of the maximum upwelling height to the reef height around the porous square artificial reef is about 2∶1. To some extent, the structure of the artificial reef provides a favorable role for the diversity of flow patterns around the reef. The spacing of the porous square artificial reef has a great influence on the number, size, distribution, and direction of vortices between the two reefs. Within a certain range, the larger the spacing, the larger the vorticity and the wider the distribution range. Beyond a certain range, the vorticity does not increase and the distribution range does not expand. The larger the spacing of the porous square artificial reefs, the larger the influence area of the back eddy current in the X and Y directions is. The results clearly show the flow field effects of artificial reefs with different disposal spaces, which is of great significance to the deployment and layout of artificial reefs under specific conditions.

Abstract:Mannan-binding lectin-associated serine protease 1 (MBL associated serine protease 1, MASP1) is an important activator in the complement lectin pathway. In this study, the cDNA of the MASP1 gene from Cynoglossus semilaevis (CsMASP1) was cloned using a RACE method based on the partial sequence of CsMASP1, and gene expression was performed by qRT-PCR. The results showed that the full length of cDNA was 2507 bp in size, including a 5′-untranslated region (UTR) of 82 bp, 3′-UTR of 142 bp, and a complete open reading frame (ORF) of 2283 bp, encoding 760 amino acids. The theoretical isoelectric point (pI) of the predicted protein was 5.33 and the molecular weight was 84.95 kDa. Homologous alignment showed that the amino acids sequence of CsMASP1 had a high identity with those of other species, approximately 42%~76%. The CsMASP1 gene was expressed in all tested tissues (liver, intestine, spleen, head-kidney, gill, blood, brain, skin, heart, trunk-kidney, and gonad) in the healthy C. semilaevis and the highest expression was in the liver (185.4). To study the expression patterns of the CsMASP1 gene in an immune response, the specific expression of CsMASP1 was performed after Vibrio anguillarum infection. The results showed that the expression of the CsMASP1 gene was up-regulated in the liver, gill, blood, intestine, head-kidney, and spleen after V. anguillarum infection. The most significantly up-regulated expression and the peak level at 6 h reached 15.4 times baseline in the spleen. The results indicate that the CsMASP1 genes are involved in the immune response.

Abstract:To determine the optimal dietary selenium requirement of golden pompano (Trachinotus ovatus), a total of 450 fish with an initial body weight of (15.04±0.20) g were randomly assigned into 6 groups with 3 replicates per group and 25 fish per replicate. The fish were fed isonitrogenous and isolipidic diets with sodium selenite (Na2SeO3) as the selenium source for 50 days, which the selenium contents were 0.41, 0.60, 0.73, 0.80, 0.90 and 1.12 mg/kg, respectively. The results showed that weight gain rate and specific growth rate firstly increased and then remained stable with the increased dietary selenium content, while the feed conversion ratio had an opposite trend. No significant difference was found in the whole body composition (P>0.05). In serum, with the dietary selenium levels increasing, the contents of albumin and high density lipoprotein cholesterol firstly increased and then decreased, while the activity of alkaline phosphatase increased and then remained stable. The selenium in the feed had significant effects on the activities of glutathione peroxidase and superoxide dismutase in the serum, and glutathione peroxidase, glutathione S-transferase, glutathione reductase, catalase in the liver (P<0.05). As the dietary selenium levels increased, the activities of glutathione peroxidase, glutathione S-transferase and catalase firstly increased and then remained stable, whereas the activities of superoxide dismutase and glutathione reductase increased and then decreased. The selenium levels in feed significantly affected the selenium concentration in the whole body (P<0.05), as the dietary selenium content increased, whole body selenium concentration increased and then remained stable. Broken-line regression analysis based on the weight gain rate, serum glutathione peroxidase activity and whole body selenium concentration indicate that the optimal dietary selenium requirements for golden pompano are 0.66, 0.82 and 0.76 mg/kg, respectively.

Abstract:This work focused on the histological study of the ontogeny of lymphoid organs by paraffin tissue sections and HE staining techniques in Eleutheronema tetradactylum, from 1 to 60 dph (day post hatching). The results showed that in the conditions of salinity 9.0±0.5 and water temperature (28±2)℃, thymus primordium appears at 3 dph that composed of 4~6 layers of undifferentiated stem cells and lymphocyte-like cells; thymus differentiated rapidly and mainly filled with lymphocytes; at 25 dph, the cortex and medulla are clearly distinguished and thymus development was basically completed. Similarly, the head kidney primordium formed at 3 dph, it consists of pronephric tubules and a few of hematopoietic stem cells; at 5 dph, the head kidney began to lymphatize when the thymic lymphocytes migrate there, and hematopoietic stem cells differentiated into different types of cells as the fish grew; at 18 dph, pronephric tubules began to degenerate and disappeared completely until 53 dph, when the head kidney is mainly composed of lymphopoietic tissue supported by reticular endothelial system. At 7 dph, the spleen primordium appears and begins to lymphatize obviously until 16 dph. The endothelial system of spleen is more developed than that of head kidney, but its development speed is significantly slower than thymus and head kidney, and lymphocytes are less than in the thymus and head kidney. These observations suggested that the respective lymphoid organs primordium becomes the thymus, head kidney and spleen successively. The structure and function of the lymphatic organs in E. tetradactylum have not been fully developed and maybe one of the main causes of high mortality during the metamorphosis period. This study is of great significance for optimizing breeding conditions, improving juvenile cultivation and healthy aquaculture technology.

Abstract:Iridovirus has a wide infection spectrum in aquatic animals, which is harmful to aquaculture. In spotted knifejaw (Oplegnathus punctatus), iridovirus is the major factor causing large-scale mortality. Iridovirus infection results in high mortality rate and thus limits the development of the spotted knifejaw industry. As an important immunoregulatory factor, TGF-β1 plays a vital role in viral immune response. In order to study its role in the process of iridovirus infection, we have cloned this gene and studied its spatiotemporal expression patterns. The total length of TGF-β1 gene is 3157 bp, including 5′-untranslated region (UTR) of 712 bp, 3′-UTR of 1278 bp. The open reading frame length is 1167 bp that encodes 388 amino acids, including 6 exons and 5 introns. Homologous alignment showed that the amino acid sequence of TGF-β1 in spotted knifejaw had a close identity to Cynoglossus semilaevis, of about 76.67%. TGF-β1 is widely distributed in tissues, and high expressed in the head kidney, intestine, liver, skin, but shows a relatively low expression in the spleen and kidney. To further illustrate the expression patterns of TGF-β1 during viral infection, we have analyzed the expression patterns of TGF-β1 in the spleen, liver, kidney, and head kidney at different time points after iridovirus infection. In head kidney, spleen and liver, the expression of TGF-β1 was increased post infection. The peak level in the spleen and liver appeared 4 days post infection (dpi), and in the head kidney the peak appeared at 10 dpi. In the kidney, viral infection seemed to downregulate TGF-β1 expression. The highest expression was observed at day 0, then decreased at 4 dpi and reach the lowest level at 7 dpi. At 10 dpi, the expression had recovered but still lower than level of day 0. These results suggest that TGF-β1 could respond to iridovirus infection and may play an important role in the process of viral immunity. However, the different expression pattern of TGF-β1 in different tissues after viral infection requires further study.

Abstract:The long-spread nuclear element-1 (LINE1) retrotransposon is a mobile element in genome. Previous comparative genomic studies found that Antarctic Notothenioid fish underwent a long low-temperature adaptation evolution, and compared with Notothenioid fish outside the Antarctic circle, LINE1 genes were duplicated by 8~300 fold. The link between this augmentation and the resistance of fish to cold is not known. In this study, zebrafish (Danio rerio) embryonic fibroblasts ZF4 were exposed to a low temperature (18℃) for 5 days and 30 days, and adult zebrafish were exposed to a low temperature (10℃) for 3 h, 6 h, 1 d, 3 d, and 5 d. The mRNA expression of LINE1 was examined using RT-qPCR. The promoter regions of zebrafish LINE1 gene were cloned and the biological activity of LINE1 5'UTR at low temperature were verified in ZF4 cells by using the dual-luciferase reporter system. The following results were obtained: (1) In ZF4 cells, LINE1 mRNA expression was decreased by short-term low temperature treatment, but was significantly increased by long-term low temperature treatment. (2) In adult fish, LINE1 mRNA expression was decreased by short-term low temperature treatment, but was significantly increased in long-term low temperature treatment. (3) The LINE1 5'UTR was found to be biologically active in ZF4 cells. (4) It was found that during low temperature treatment (18℃, 3 d), the reporter gene signal was weakened, which indirectly indicated that the LINE1 promoter activity was weakened. The results showed that low temperature stress affected LINE1 expression in fish, which presents a foundation for further study on the mechanism of action of LINE1 in fish adaptation to a low temperature environment.

Abstract:To study the effect of morphological difference and morphological characteristics on body weight of reciprocally-crossed subgroups of Oreochromis niloticus × O. Aureus, this study undertook to track and measure body weight and seven growth-related morphological traits, including total length, standard length, head length, body depth, caudal peduncle length, caudal peduncle depth, body width. Fifty individuals were randomly selected in the orthogonal group, and 50 males and 50 females were randomly selected in the backcrossing group for our analysis. All experimental fish are cultured in the same pond. The results showed that the total length, body depth and caudal peduncle depth 3 traits have a major impact on the weight of forward hybrid subgroups, thus establishing a multivariate regression equation related to body weight as YBW=–154.286+9.016XTL+10.065XBD+17.884XCPD; Meanwhile for female individuals of reverse hybrid subgroups, total length and body depth, were two traits found to have a major impact on body weight, thus establishing a multivariate regression equation related to body weight as YBW=–92.582+7.415XTL+8.727XBD; for male individuals, standard length and body depth are the two traits which have a major impact on body weight, thus establishing a multivariate regression equation related to body weight as YBW=–120.299+8.661XSL+16.590XBD. In order to eliminate the influence of differences in body size among the individuals, we obtained seven proportion characteristics including BS, TS, HS, BDS, CLS, CDS, and BWS, respectively. In the characteristic coefficients plots of principal components factor scores, those seven proportion characteristics were divided into two groups, the first group concluded TS, BDS, CDS, BWS and HS, the other concluded BS and CLS. We drew a scatter plot through the score coefficients of every individuals in principal component factors PCR1 and PCR2. In the plot, the individuals of forward hybrid males could obviously be differentiated with reverse hybrid females. The conclusion showed that the morphological traits affecting body weight were different between different hybridization methods and different genders. In the selection of broodstock and the breeding of progeny, comprehensive traits selection should be adopted to improve the accuracy and stability of the breeding results.

Abstract:Controlling the inbreeding level is an important task in animal breeding. Genetic analysis such as genetic diversity and genetic distance estimate could provide information for the artificial selection of animals. In the present study, the genetic information of Pacific white shrimp Litopenaeus vannamei from six different populations in China were analyzed using genotyping data of eight SSR loci. The results showed that the mean Na ranged from 3.67 to 9.33, the mean Ne range from 2.20 to 5.67, the mean Ho ranged from 0.12 to 0.71, the mean He ranged from 0.41 to 0.81, and the mean PIC ranged from 0.36 to 0.76. The cluster analysis results showed that the individual shrimps from populations of different companies were clustered in different nodes. The individual shrimps from three hatcheries from the same company were clustered in one node. Among the six populations of L. vannamei, the genetic identity ranged from 0.4229 to 0.8265, and the genetic distance ranged from 0.1905 to 0.8607. The mean value of FST was 0.1837. The FIS value was 0.2514. And the Ho value was smaller than the He value. The results suggested that genetic diversity between L. vannamei from different populations could be high, while, genetic relationship of L. vannamei in populations of the same company might be quite close. There might be an inbreeding phenomenon.

Abstract:In this study, homogenization, centrifugation, microscopy, and marker enzyme assays were used to study the separation and identification techniques for subcellular fractions of the digestive gland tissues of Chlamys farreri. The results showed that after Hoechst 33258 staining, a large number of intact cells, which were round or elliptical, with complete cell membrane and high fluorescence intensity, were observed in the 2 min homogenization group. In the 3, 4, and 5 min homogenization group, the number of intact cells gradually decreased, and many cell fragments with small morphology, weak fluorescence, and blurred outline appeared. Additionally, the blood cell counting results were consistent with the Hoechst staining results. With the increase in homogenization time (2~5 min), the broken cell rate was increased under an optical microscope and when the 2 min homogenization group was used as the control group, the broken cell rate reached 94.24% in the 5 min homogenization group. There were more fluorescent particles in C2 with appropriate size, and clear structure, and fewer fluorescent particles were observed in other separated fractions, when fractions (S2, C2, C4, S5, and C5) of the digestive gland tissues of C. farreri were stained with Hoechst 33258. Therefore, the nucleus mainly presented in the C2 fraction. At the same time, the marker enzyme activity of the cell membrane (5ʹ-nucleotidase), mitochondria (succinate dehydrogenase), cytoplasmic (lactate dehydrogenase), and microsomes (glucose-6-phosphatase) accounted for a high proportion (63.90%, 64.89%, 77.82%, and 67.55%) in the S2, C4, S5, and C5 fractions, respectively; however, there were also a small amount found in other subcellular fractions. As a result, the separated fractions of S2, C2, C4, S5, and C5 were cell membrane, nucleus, mitochondria, cytoplasm, and microsomes, respectively, and the technical methods for separation and identification of subcellular fractions of the digestive gland tissues of C. farreri were successfully determined.

Abstract:The effects of acute hypersalinity stress on the antioxidant and photosynthetic enzyme activities of Gracilaria chouae were studied. Plants were exposed to different levels of salinity ranging from 33 (control) to 60 under laboratory conditions. After incubation, plants were then transferred to seawater with a controlled level of salinity and recovered after 12 or 24 hours, respectively. The activity of antioxidant enzyme SOD increased (P<0.05), the activity of POD was fluctuated (P<0.05), the activity of CAT gradually decreased without significant difference (P>0.05) but the content of MDA was significantly increased (P<0.01). The activity of SOD、POD、CAT and MDA reached the maximum in 50~55 psu groups but decreased significantly at salinity 60; The activity of Rubisco, a key enzyme in photosynthesis of C3, gradually decreased with the increase of salinity (P<0.01). The content of CA slightly increased with the increase of salinity (P<0.05). With the increase of recovery time, SOD, POD and CAT activities gradually increased (P<0.05), and the activity of each antioxidant enzyme showed a maximum value in 50~55 psu groups, but MDA content decreased considerably (P<0.05). Rubisco activity was significantly higher than that in 0.5 h (P<0.05), and CA content fluctuated with salinity. Short period high-salinity stress significantly affected the activities of antioxidant enzymes and photosynthetic enzymes in G. chouae. Algae responded to hypersalinity stress by increasing the activities of antioxidant enzymes, and enhancing the absorption and utilization of inorganic carbon by CA. The alga gradually returned to the normal level after the stress was removed. The purpose of this study is to provide a theoretical basis for improving the efficiency of large-scale cultivation of G. chouae, and to provide basic data for the study of salt tolerance mechanism of macroalgae.

Abstract:As an economically important alga growing in the intertidal zone, Pyropia yezoensis has the unique characteristics of adapting to high ultraviolet radiation in the open air and to desiccation conditions. In this experiment, light without UV-B radiation was used as a control, and low UV-B radiation of 0.5 W/m2 and high UV-B radiation of 2 W/m2 were used to detect changes in chlorophyll fluorescence photosynthetic parameters, multi-spectral fluorescence parameters, and tyrosinase activity in response to UV-B ultraviolet radiation in the gametophytes of P. yezoensis. The results showed that the chlorophyll fluorescence photosynthetic parameters (QY_max, NPQ_Lss, qP_Lss, Rfd_Lss) of P. yezoensis under UV-B radiation displayed a gradient decline with irradiation time, and the values of photosynthetic parameters were lower at high radiation intensity (2 W/m2) than at low radiation intensity (0.5 W/m2). The early stress parameters of F440/F690 and F440/F740, which are positively related to secondary metabolites such as phenol or aldehyde concentration, showed that the group under conditions of 2 W/m2 entered a forced state earlier than the group under 0.5 W/m2. Secondary metabolites such as phenol or aldehyde showed concentration declines. F690/F740, which is negatively correlated with chlorophyll concentration, indicated that the chlorophyll concentration under 0.5 W/m2 irradiation was higher than that under no UV-B irradiation, but was lower than the maximum value in the rising period of 2 W/m2 irradiation. The chlorophyll concentration increased initially and then decreased rapidly after 4 h under 2 W/m2, indicating that the chlorophyll concentration is less sensitive to UV-B radiation under low radiation intensity, whereas it is more sensitive under high radiation intensity. The results showed that the tyrosinase activity was significantly higher in P. yezoensis gametophytes irradiated with UV-B than in the control group and that the enzyme activity under 2 W/m2 UV-B was higher than that under 0.5 W/m2 UV-B.

Abstract:In this culture experiments of Litopenaeus vannamei, we explore the effect of compound probiotics on the ability of L. vannamei to resist Vibrio parahaemolyticus infection at different experimental stages. One strain of Bacillus licheniformis (BL-9), one B. subtilis (BS-12), and one Pseudoalteromonas flavipulchra (CDM8) were selected to make up a compound of probiotics at the same concentration (107 CFU/ml). The effect of compound probiotics on the V. parahaemolyticus infection of L. vannamei was observed by adding the compound probiotics to the culture water of the L. vannamei. The experiment took place over 30 d, including a temporary period (7 d), a probiotics immersion period (15 d), and a V. parahaemolyticus infection period (10 d). The experiment results showed that the addition of compound probiotics in the culture water could significantly increase the total number of bacteria culture in the water and the intestinal tract of L. vannamei (P<0.05). The cumulative survival rate of shrimp in the experimental group was (73.33±6.83)% at the end of the infection periodwhich was significantly higher than that of the positive control group (25.33±15.43)%. The disease-resistant-related gene: heat shock protein 70 (Hsp70), β-1,3-glucan binding protein-lipoprotein (βGBP-HDL), lipopolysaccharide-β-1, 3-glucan binding protein(LGBP), crustin, and immune related enzymes catalase (CAT), was up-regulated by different degrees in the probiotics immersion phase. And all the genes up-regulated extensively during the V. parahaemolyticus infection stage, but expressed at different levels. The results suggested that the compound probiotics with BL-9, BS-12, and CDM8 in water could improve the ability of shrimp to resist V. parahaemolyticus infection. The increase of disease resistance of L. vannamei may be related to the colonization of probiotics in the intestinal tract, and the expression level of disease resistance related genes and catalase activity in L. vannamei. It is hoped that the results of this study can provide a reference for the application of compound probiotics in the cultivation of L. vannamei.

Abstract:Flatfish are the major industrial aquaculture marine fish species bred in North China. During the culturing process, members of this species are exposed to infection from a variety of pathogens. Diseases caused by bacterial pathogens are the major cause of harm to cultured flatfish in China. To investigate the bacterial pathogens that affect flatfish, we focused on 124 strains isolated from organs of diseased flatfish in Shandong, Jiangsu, Hebei, Tianjin and other similar places between 1999 and 2012. The 16S rRNA gene of the isolates was sequenced, analyzed using BLAST (GenBank), and subjected to phylogenetic analysis by using Mega 5.05. The results identified 66.90% of isolates as Vibrio (83 strains), 8.90% as Aeromonas (11 strains), 3.20% as Edwardsiella (4 strains), and other 15 genera (26 strains). According to the phylogenetic tree, 66 strains were identified as 16 species; the dominant species were V. alginolyticus, V. harveyi, V. anguillarum, V. damselae, V. furnissii, V. splendidus, A. allosaccharophila, A. salmonicida, and E. tarda. To evaluate the pathogenicity of isolates, the virulence of V. anguillarum and E. tarda strains isolated from diseased fish was further determined by experimental infection based on the 50% lethal dose (LD50) in turbot (Scophthalmus maximus). The results showed that seven V. anguillarum strains and three E. tarda strains were pathogenic to fish. The LD50 values were 105.1 to 106.8 CFU/fish for pathogenic V. anguillarum and 103.4 to 104.1 CFU/fish for pathogenic E. tarda. There were also two strains of V. anguillarum and one strain of E. tarda that showed low virulence to turbot, with an LD50 higher than 107 CFU/fish. The presented results provide significant information to ascertain the bacterial pathogens of flatfish, which is important for establishing strategies for the epidemiology, monitoring, and control of bacterial diseases.

Abstract:The largemouth bass Micropterus salmoides has been widely cultured in China due to its considerable economic value. Recently, the species suffered from serious M. salmoides rhabdovirus (MSRV) disease during the juvenile phase, particularly in aquaculture conditions. In this study, a strain of M. salmoides rhabdovirus isolated from dying juvenile fish was cultured in a grass carp ovary (CO) cell line. To take advantage of passive immunity, we explored anti-MSRV immunoglobin Y (IgY) by discontinuously immunization on laying hens with a formalin-killed vaccine of MSRV. The antibody was purified by saturated ammonium sulfate, and displayed virus resistance with an ELISA antibody titer of 1∶256 detected. The bioactivity of anti-MSRV IgY was tested simultaneously after being added to a CO cell line incubated with MSRV. This antibody showed antiviral activity, with 38.29% of neutralizing effectiveness detected at a dilution of 1∶64. The RNA copies of MSRV in the test group were clearly fewer in number compared with those of members of a control group. By the florescent real-time quantitative PCR, the intracellular lectin experienced significantly up-regulated pick-up to nearly 10-fold at 72 h compared with the control group. In conclusion, we successfully isolated a strain of MRSV and cultured it in a CO cell line. Anti-MSRV IgY prepared with vaccinations of inactive virus displayed antiviral activity in this study, laying a foundation for the application of yolk antibodies as an immune preparation.

Abstract:Telomerase reverse transcriptase (TERT) gene is a key structure and major regulatory subunit of telomerase. TERT synthesizes telomeric DNA repeats by reverse transcription of telomerase RNA template sequences and adds them to the ends of chromosomes to maintain and extend the ends. Golden cuttlefish (Sepia esculenta) is an annual species that dies quickly after spawning. This characteristic makes it a potential research object for the study of reproduction and aging. In this study, the phylogenetic and homologous sequence analysis revealed that the gene was a Sepia esculenta TERT gene with a sequence length of 2415 bp. Quantitative Real-time PCR (qRT-PCR) was used to detect the relative expression of TERT gene in the growth stages, spawning stages and aging stages of S. esculenta, and to analyze life cycle differences and gender differences. The research results show that TERT gene expression in six tissues, including heart, liver, pancreas, gill, gonad and esophageal nerve mass, showed a downward trend, which was supposed to be related to the decline of organ division and proliferation in the near-death stage. TERT gene has obvious specificity in different tissues of, Sepia esculenta. It shows that the aging status of different tissues and organs of Sepia esculenta is different. The results of this study can provide basic data for the further study of the regulation mechanism of Telomerase in reproduction and senescence of cephalopod.

Abstract:With the increase of fishing intensity, fish gradually evolve to adapt in response to fishing pressures to maintain the reproduction of the population. This process is called fishing-induced evolution (FIE). Nowadays, many fish in the world have evolved these biological characteristics. For example, Atlantic cod (Gadus morhua), small yellow croaker (Larimichthys polyactis) and other fish became smaller size and earlier mature. These lead to further the simplification of fish population structure, the decline of ecosystem stability and the reduction of fishing economic benefits, finally FIE seriously affects the sustainable development of fish resources in many countries. Therefore, it is essential to recognize the fishing-induced adaptive evolution and grasp the mechanism of fishing effects on fish resources, in order to formulate a scientific and rational strategy for recovery and management of fishing resources. Although FIE has caused wide concerns, the mechanisms underlying the impact of fishing on physiological, ecological and genetic characteristics of fish are not clear, especially in the dynamic environment of climate change and multi-species interactions. The role of FIE is more complex due to a number of influencing factors and the complex evolutionary process. The existing studies mainly focus on fishing-induced changes in fish biological traits, computer-simulated population resilience and fish resource management strategies, but rarely on the mechanisms of FIE. Here, we reviewed the main research methods of fish FIE including methods of field ecology, experimental ecology, numerical simulation, and genetics. We summarized the related research results that fishing affects fish body length, sexual maturity, behavior and other factors, by selecting the larger individuals caught by the most important kind of fishing, bottom trawling, and analyzed the effects on the fish population recovery and management of fish stocks. Finally, we concluded that the key scientific problems to be solved, in order to provide help for further FIE research and scientific management of fish resources.

Abstract:Melanocortins are the products of the precursor protein proopiomelanocortin (POMC) with extensive localization in the central nervous system and peripheral tissues. Melanocortins play important roles in the skin, stress response, immune system, feeding behavior, and sexual function. In recent years, the -melanocyte stimulating hormone (-MSH) and melanocortin-4 receptor (MC4R) have received considerable attention for their regulation of energy homeostasis and reproduction. Previous studies have shown that POMC, -MSH, and MC4R regulate food intake and the reproductive system by mediating the secretion of hormones related to the hypothalamic-pituitary-gonadal (HPG) axis. In this review, we summarize the physiological functions of POMC, -MSH, and MC4R in energy homeostasis and reproduction. We also summarize the results of several studies reporting the pharmacological characteristics of teleost MC4R and discuss the potential commercial applications in aquaculture.