Abstract:Transcription factors Runx2 and Osterix play a vital role in the formation and differentiation of the skeleton in mammals. To date, there have been few reports on the regulatory mechanisms of the skeleton development in fish. In this study, we cloned the cDNA sequences of Runx2 and Osterix in Cynoglossus semilaevis, and examined their expression patterns in 13 tissues of both female and male adults using qRT-PCR. The results showed that Runx2 and Osterix mRNA were highly expressed in spleen, and moderately expressed in dorsal fin and brain. Next we detected and measured the levels of Runx2 and Osterix mRNA at early developmental stages including the egg, larva, juvenile and fingerling stages. The temporal expression patterns are: 1) the mRNA level of Osterix was always significantly higher than Runx2 during all developmental stages in this study; 2) at stages prior to hatching, the highest level of Runx2 was observed in the cleavage and gastrula stages and then it dropped to a very low level, and the Osterix mRNA level increased and reached the peak in the embryonic stage; 3) at early larvae stages (1−5 days old), the expression of both Runx2 and Osterix first increased followed by a decline; 4) as for the 10−90 day-old fish, there was no variation in the expression pattern of Runx2 or Osterix mRNA. These results suggested that Runx2 and Osterix could participate in the regulation of early development in C. semilaevis. However, further studies are needed to explore their roles in the skeleton development.

Abstract:Seasonal investigations on zooplankton community in Liusha Bay were carried out from May 2012 to January 2013. A total of 41 species and 17 groups of pelagic larvae were recorded, in which the copepod was the majority (29 species). Subeucalanus subcrassus, Brachyuran larva and Macruran larva were the dominant species seasonally in three quarters. The annual average density and biomass were 48.12 ind./m3 and 13.43 mg/m3, respectively. In general, the density, biomass and diversity index of zooplankton were lower in autumn than those in spring and summer, and these indices in inner bay were lower than those in outer bay. The zooplankton density was barely positively correlated to nitrite, while the zooplankton biomass had significant correlations with multiple environmental factors such as nitrite, ammonium and total nitrogen. Compared with the control (non-culture area), the density and biomass in the main scallop culture area, the fish culture area and the oyster culture area were lower. Rarely found in culture areas, large and medium-sized zooplankton mainly appeared in the non-culture area. In autumn, the density of Acartia erythraea was higher in the fish culture area than those in the other areas. During winter, the diversity index of zooplankton in the main scallop culture area was the highest (2.97). Large and medium sized species of zooplankton mainly appeared in the control area in all reasons. In spring, Subeucalanus subcrassus appeared with absolute predominance (66.04%) in the control area. In summer, the biomass of S. subcrassus and Flaccisagitta enflata were the highest in the control area (accounting for 0.3% and 0.8%, respectively) and the lowest in the main scallop culture area (accounting for 0 and 0.8%, respectively). In autumn, a spot of A. erythraea were merely found in the control area and the fish culture area. The density and biomass in the main scallop culture area were rapidly increased from autumn to winter, although they were lower than those in the non-culture area but higher than those in the fish culture area and the oyster culture area. The results indicate an obvious decline in the density and biomass of zooplankton and a severe miniaturization of zooplankton in size in Liusha Bay with the culture of fish and shellfish.

Abstract:To identify snailfish specimens collected in the central and southern Yellow Sea, both morphology method and cytochrome oxidase subunit geneⅠanalysis were conducted in this paper. The results showed that 22 specimens were Liparis tanakae according to meristic and measurable characteristics, including the fin ray number of pectoral fin, anal fin, dorsal fin, caudal fin, the number of pyloric caecum, the ratios of head length/body length, body depth/body length, head length/snout length, interorbital space/eye diameter etc. In all L. tanakae specimens, 4 specimens were covered with obvious brown transverse spots. Five specimens had irregular spots, white radiation lines in ocular region, obvious longitudinal grain in the head and caudal fin. Nine specimens had the brown or black brown fine spots on the head and body side, one white patch in the base of caudal fin, and black anal fin. Another 4 specimens had reddish-brown with longitudinal striate, the fin membrane edge of dorsal fin, anal fin, pectoral fin, and caudal fin. There was one specimen belonged to Liparis chefuensis that had the irregular white spots in the head and body back, long caudal fin, the round convex at its back end, 6−7 dense spots in the two sides of the base of dorsal fin. These results were supported by the cytochrome oxidase subunit geneⅠanalysis. The genetic distance between 22 L. tanakae specimens were 0.002−0.003, and the genetic distance between L. tanakae and L. chefuensis was 0.134. The genetic distance between L. tanakae and the other species, for example L. dennyi, L. gibbus, L. fucensis were 0.057−0.067. These findings indicated that Liparidae species in the Yellow Sea were mainly composed of L. tanakae.

Abstract:In the present study, monthly carapace length frequency data of Culter alburnus were collected from the set net fishery survey in the waterway connecting the Poyang Lake and the Yangtze River from March 2012 to February 2013. ELEFAN І and Shepherd’s methods in the software package FiSAT II were used to analyze the growth, mortality rates and recruitment pattern of an unexploited population of C. alburnus. The results showed that the length of C. alburnus population ranged from 93 to 645 mm, and that the relationship between body length (L, mm) and body weight (W, g) can be expressed as W=0.9×10-5L3.029(R2=0.975, n=317). The estimated parameter for von Bertalanffy growth equation was L∞=677.25 mm，K= 0.140, and t0 =−0.854. Total mortality (Z) was 1.514/a, natural mortality (M) was 0.173/a, and fishing mortality (F) was 1.341/a. The exploitation rate of C. alburnus was 0.886, suggesting resources of C. alburnus were on the state of overexploitation in the study area. The recruitment pattern with less efficiency from April to August suggested that fishing ban period should be adjusted in order to restore and conserve the populations of C. alburnus.

Abstract:Most water environmental factors have a nonlinear correlation. To assess sea water quality, the Back Propagation (BP) artificial neural network model was established based on the concept and principle of artificial neural network. Taking DO, COD, DIN, PO43- and petroleum as the evaluation factors, the BP neural network was established to evaluate the water quality for Dagu River wetland. The results indicated that the sea water quality of Dagu River was worse than the class Ⅳ water quality standard, and the water quality of its surrounding area were or exceeded the class III water quality standard. The survey sea area was mainly affected by inorganic nitrogen and phosphate. The study found that the number of inorganic nitrogen content that exceeded Ⅳ levels accounted for 59.3% of all respondents, and that eutrophication was obvious. These results indicated that BP neural network method was reasonable in design and higher in generalization compared with single factor evaluation and Nemerow pollution index, and that it is an objective, effective and practical environmental quality evaluation method. Thus, BP artificial neural network was a better level of fast, handy and valid ability to evaluate the sea water quality.

Abstract:The humphead wrasse, Cheilinus undulatus, is one of the most famous endangered reef fish in the world. As a social hermaphroditic fish, it has special biological characteristics and high economic value. In this study, we observed the embryonic development of C. undulatus and analyzed its features under a microscopy. Six periods, including zygote, cleavage, blastula, gastrula-neural, organogenesis, and hatching, were divided during the embryonic development of C. undulatus. These 6 periods include 26 stages, including zygote, blastoderm formation, multi-cell, morula, and tail bud stage etc. The results showed that C. undulatus had a float, transparent, spherical egg with a big oil globule. The diameter (635.6±50.0) μm of the egg was obviously shorter than eggs of many marine fishes. The neural plate appeared in the mid to late gastrula stage, and the embryonic development of C. undulatus was remarkably quicker than other fishes under the same condition. The fertilized eggs were hatched after 15.5 h at water temperature of 27.7−29.0℃ and salinity of 30. The total length of newly-hatched larvae were (1305.5±50.0) μm with an elliptic large yolk sac over the head and a shining oil globule in the front of it. These results suggest that the embryo development of C. undulatus was faster than many other fishes due to smaller egg. The special embryonic development features of the humphead wrasse may cause high mortality in the post embryonic stage.

Abstract:To investigate the effects of soy peptides on hepatic metabolism of juvenile starry flounder (Platichthys stellatus), two isonitrogenous (43.98±0.14% dry weight) and iso-energetic (19.89±0.08 kJ/g dry weight) experimental diets were formulated to contain 0% SPH (control, FM) and 24% SPH (SPH) respectively. Two hundred and forty juvenile starry flounders (initial weight of 5.73±0.36 g) were randomly distributed to 2 groups with three replicates per group (40 fish/replicate). Each group was fed one diet for 50 days before collecting liver samples for analysis. The results showed that 448−470 protein spots were detected in the gel area of pH 4−7 and Mr 14.4−97.4 kDa after 2-dimensional gel electrophoresis. Among them, fourteen hepatic proteins showed over 2-fold difference in expression abundance including 3 structural proteins (intermediate filament protein ON3-like, type II cytoskeletal 8-like isoform X2 and β-actin) and 11 proteins involved in different metabolism. Nine metabolic proteins and 3 structural proteins were up-regulated by at least 2-fold and other 2 metabolic proteins were decreased by 2-fold in fish fed SPH diet compared those fed FM diet. The present results revealed that SPH affected hepatic metabolism by enhancing synthesis of high density lipoprotein and stress protein, promoting glycolysis metabolism for energy production while reducing synthesis of trypsin. The present study elucidated the global metabolic response of fish liver to soy peptides using comparative proteomics technology and provides a theoretical basis to apply the novel plant proteins in aquatic feed.

Abstract:Serine proteases are enzymes that have serine, histidine and aspartic acid in their active domain and same catalytic mechanisms, which play important roles in many diseases and intracellular signal transduction. In this study, we amplified the coding sequence and promoter sequence (2605 bp) of serine protease I-1 from Japanese flounder Paralichthys olivaceus (PoSP I-1). We identified 9 single nucleotide polymorphisms (SNPs) and 28 SNPs in the coding sequence and promoter sequence of PoSP I-1, respectively. The analysis of all SNPs indicated that the frequency of SNP365A/G in the coding sequence of PoSP I-1 is significantly different between the resistant group (60%) and the susceptible group (40%) (P=0.01). Vibrio anguillarum injection reduced the expression of PoSP I-1 in the susceptible individuals but induced its expression in the resistant individuals. Moreover, PoSP I-1 in the resistant individuals is higher than that in the susceptible individuals. These results implied that PoSP I-1 is involved in the resistance of Japanese flounder to V. anguillarum. 365A/G of PoSP I-1 is a potential marker associated with the resistant Japanese flounders. In conclusion, PoSP I-1 365A/G is a candidate marker that could apply to disease resistant selective-breeding of Japanese flounder in the future.

Abstract:Chuzhou Crucian Carp (Carassius auratus in Chuzhou) is one of the natural gynogenetic crucian carp originated from Anhui Province in China. It belongs to the genus of Carassius within the family of Cyprinidae. To investigate the species status of this fish, we performed the direct DNA sequencing on the PCR products of the complete mitochondrial DNA (mtDNA). The total length of the mtDNA was 16581 bp, including 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and a non-coding control region. The composition and location of genes in the mitochondrial genome of Chuzhou Crucian Carp were consistent with those of Cyprinidae fishes published in GenBank. The tRNA genes formed typical secondary structures except for tRNA-Ser (AGY). The COⅠ gene had GTG as its initiation codon, and the other 12 protein-coding genes had ATG as the initiation codon. Among the 13 protein-coding genes, 9 had complete stop codons but COⅡ, ND3, ND4 and Cyt b had an incomplete T as the stop codon. Sequence analysis showed that there was high similarity between the mtDNA sequences of Chuzhou Crucian Carp and other species in genus Carassius recorded in GenBank (>94%). The nucleotide composition of Chuzhou Crucaian Carp was 31.6% (A), 26.2% (T), 16.1% (G) and 26.2% (C). We conducted the phylogenetic analysis of the mitochondrial genomes of 9 Carassius fishes and 1 Cyprinus carpio, based on their nucleotide and amino acid sequences of all protein-coding genes. The results indicated that the phylogenetic relationship between C. auratus gibelio in Chuzhou and in Fangzheng was the closest while C. auratus gibelio in Chuzhou and Carassius carassius was the farthest. Our study may provide basic data and contribute to the classification of Carassius and Cyprinidae fishes.

Abstract:Molecular biology technologies have been widely used in aquatic animal disease diagnosis and molecular pathology studies, which require high quality of nucleic acid. However, how to preserve sample quality at normal temperature is rarely investigated. In this study, we compared the preserving effect of RNA in the tissues of shrimp Litopenaeus vannamei stored in different preservation solutions at normal temperature to find one preservation solution that can be used at normal temperature and long-distance transportation. Saturated solutions of ammonium sulfate and ammonium acetate in a serial of solvents with different ethanol concentrations were used to preserve shrimp tissues. The results showed that ammonium acetate has higher solubility in ethanol solution than ammonium sulfate. The molarity of ammonium ion of ammonium acetate is steadier in 0−80% ethanol. Ammonium acetate penetrates into the tissue of intact shrimp faster and reaches a higher concentration than ammonium sulfate does. RNA with better integrity, higher copies, and longer half-life period was achieved in the tissue preserved in more than 70% ethanol, saturated ammonium sulfate in the solvent of 50% and 70% ethanol, saturated ammonium acetate in the solvent of 50% ethanol. These results suggest that the saturated ammonium acetate in 50% ethanol as the solvent (pH=6.0) can be used as sample preserving solution to preserve RNA in shrimp tissues at normal temperature.

Abstract:Corbicula fluminea is a common macrozoobenthos in the freshwater of the Hongze Lake, which plays an important role in the cycle of mass and energy fluxes of fresh water ecosystem. However, the wild source of C. fluminea has sharply decreased recently due to over-fishing and water pollution. The genetic diversity of C. fluminea in the Hongze Lake has not been widely investigated. The present study analyzed the genetic diversity of C. fluminea population in the Hongze Lake using mitochondrial DNA cytochrome coxidase subunit Ⅰ (COⅠ) gene molecular marker. The mitochondrial DNA COⅠgene fragments were amplified and sequenced from 50 individuals of wild C. fluminea in the Hongze Lake. The contents of A, T, G and C in the 614-base pair fragments of COⅠgene were 22.6%, 42.4%, 21.0% and 14.0%, respectively, and the content of A+T was significantly higher than that of G+C. Sixty-seven polymorphic sites were detected, accounting for 10.9% of the total sequences, and of which sixty-three were parsimony- informative sites and four were singleton sites. Fifteen haplotypes were defined in 50 individuals of C. fluminea. The mean haplotype diversity, nucleotide diversity, and the average number of nucleotide difference in the C. fluminea population were 0.870, 0.045 and 27.370, respectively. The genetic distance among fifteen haplotypes ranged from 0.002 to 0.095. Neighbor-joining (NJ) and maximum-parsimony (MP) trees divided fifteen haplotypes into two clades, suggesting that C. fluminea populations had significant genetic difference. Mismatch distribution analysis showed a multiple type, and Tajima’s D value (2.724) of neutrality test is positive but significantly different, demonstrating that C. fluminea in the Hongze Lake hadn’t experience a recent population expansion. These results suggest that the genetic diversity of C. fluminea population in the Hongze Lake is high, which provides scientific information for the conservation and sustainable exploitation of C. fluminea.

Abstract:In this study we explored the elimination rules of semicarbazide (SEM) and its effect on the activities of hepatopancreas enzymes in Fenneropenaeus chinensis. Experimental shrimps were fed with a diet supplemented with nitrofurazone for five days before they were randomly selected from the tank and sampled in different days after the last oral administration. The concentrations of SEM in the hemolymph，hepatopancreas, gill, muscle and carapace were measured with LC-MS/MS, and the activities of ethoxylcumarin odethylase (ECOD) and aminopyrine N-demethylase (APND) in the hepatopancreas were examined with UV spectrophotometry and fluorospectrophotometry. The results showed that 1 h post treatment, the mean concentrations of SEM in the shrimp tissues were in the order of hepatopancreas>gill>carapace>muscle>plasma. At the end of the 20th day post treatment, SEM was still detectable in all tissues and the order of the concentration was muscle>gill>carapace>plasma> hepatopancreas. The half life of the elimination phase in the muscle, carapace, gill, plasma and hepatopancreas was 5.89 d, 4.66 d, 2.95 d, 2.70 d and 1.47 d respectively. Our results indicated that the elimination of SEM was the fastest in the hepatopancreas and the slowest in the muscle, and that SEM remained in the body of F. chinensis for long. Compared to the control, the activities of ECOD and APND in the experimental group were first reduced, followed by an increase, and finally returned to the normal levels. The activity of ECOD in the experimental group was significantly lower than the control 1 h post treatment (P<0.05), and the statistical significance was even greater than 3 h post treatment (P<0.01). Afterward the activity was enhanced and became significantly higher than the control at 48 h, 72 h, 96 h, 120 h, and 240 h (P<0.01) post treatment. The activity of APND was significantly lower than the control at 6 h and 9 h (P<0.01) but obviously higher at 96 h (P<0.05) and 240 h (P<0.01), and the final level was lower than the control at 480 h. These data suggested that SEM was eliminated slowly in F. chinensis and had an impact on the activities of ECOD and APND. Moreover, ECOD and APND may be involved in the metabolism of nitrofurazone.

Abstract:To investigate the effects of different brands of commercial diets on the weight gain rate, specific growth rate, feed conversion ratio, feeding rate, and apparent protein digestibility of the juvenile sea cucumber, the juvenile sea cucumber (Apostichopus japonicus) (initial wet weight 5.0-6.7 g) were fed with the diets containing various particle diameters of Asterias echino-skin powder (two commercial feeds as control) for 60 days. The results showed that the survival rate of A. japonicus is not impacted by diets (P>0.05). The trend of the average weight gain rate was same with the specific growth rate of sea cucumber, which was higher in commercial feed 2 group and lower in commercial feed 1 group. The feed conversion ratios (FCR) of sea cucumber fed with Asterias echino-skin was the lowest (0.993) but no significant difference with the other two groups (P<0.05). The feeding rate (FR) of sea cucumber was similar between Asterias echino-skin group and commercial feed 1 group (P>0.05), but it was significantly lower than that of the commercial feed 2 group (P<0.05). The feed efficiency of sea cucumber fed with Asterias echino-skin group was significantly higher than those of other two groups that have no significant difference (P>0.05). The highest apparent protein digestibility of sea cucumber was in Asterias echino-skin group (67.28%), which was significantly higher compared with commercial feed 1 group but without significant difference compared with the commercial feed 2 group (P>0.05). These findings indicate that supplementation of Asterias echino-skin in diets could improve the growth performance and feed utilization of A. japonicus, and the Asterias echino-skin powder can be used as a feed additive.

Abstract:High scatter ratio (ScR) of feed diets and the lack of effective disease prevention and control method have been hindering the cage culture of sea cucumbers (Apostichopus japonicus). In this study we used adhesive feed with bio-gel and 3 types of feed supplements (Enteromorpha, microecologics and Chinese herbal medicine) to evaluate their effects on the growth and survival of the cultured sea cucumbers. We designed two categories of feed (adhesive feed with 20% bio-gel and control feed without bio-gel), and divided them into eight groups including the blank adhesive feed (AF-b), the enteromorpha adhesive feed (AF-en), the microecologics adhesive feed (AF-mi), the Chinese herbal medicine adhesive feed (AF-h), the blank control feed (CF-b), the enteromorpha control feed (CF-en), the microecologics control feed (CF-mi), and the Chinese herbal medicine control feed (CF-h). The survival rates (SR), the weight gain rates (WGR), the specific growth rates, the activities of protease, amylase, cellulose, and the microstructure of foregut were measured as the indicators of the effects of feed supplements during the 42-day feeding experiment. The average ScR of the adhesive feed groups (AF-b, AF-en, AF-mi, and AF-h) was reduced by 33.42% compared to the control groups (CF-b, CF-en, CF-mi, and CF-h). There was no significant difference between the 3 groups with food supplements (P>0.05). The WGR and SGR of AF-h were (41.50±1.39)% and (0.82±0.02) %/d respectively, which were the highest among all groups and the values were significantly different from other 4 groups (CF-b, AF-b, AF-en, and AF-mi) (P<0.05). The SR of AF-h (94.03%±2.28%) was the highest among all groups. The SRs of AF-h and AF-mi were significantly higher than that of CF-b and AF-b (P<0.05). The activity of amylase of AF-en, AF-mi and AF-h reached the maximum on the 10th, 20th and 30th day during the experiment, and the peak values were (1.70±0.05) U∙mg prot-1, (1.60±0.04) U∙mg prot-1 and (1.77±0.04) U∙mg prot-1 respectively. Compared to the other 4 groups, the activity of protease of AF-b fluctuated tremendously and reached (1.78±0.09) U·mg prot-1 on the 10th day during the experiment. The activity of cellulose of CF-b, AF-en and AF-b first increased during the early stage and decreased later; the activity of cellulose of AF-h continued to increase during the entire experiment; the activity of cellulose of AF-mi decreased during the first 20 days and then increased in the later 20 days. The microstructures of the foregut of the 5 groups (CF-b, AF-b, AF-en, AF-mi, and AF-h) were normal. The microscopic observation revealed an intense secretion activity of the epithelial cells in AF-mi and AF-h. The relative thickness of the mucosa of AF-b and the muscular layer of AF-en increased significantly (P<0.05). These results indicated that the adhesive feed with bio-gel could effectively decrease ScR of feed diets, and that WGR, SR and digestion activities could be increased with the addition of microecologics and Chinese herbal medicine. Furthermore, Enteromorpha did not affect the growth of cage-cultured sea cucumbers, which indicated that it could be used as a substitute in the feed diets for sea cucumbers.

Abstract:Penglai sea cucumber (Apostichopus sp.) is a newly developed aquaculture species. The nutrient composition in the body wall of Penglai sea cucumber has not been investigated widely. The current study measured the nutrient composition of Penglai sea cucumber and compared with other sea cucumber species. Results showed that the contents of moisture, crude protein, crude fat, and crude ash of the body walls of Penglai sea cucumber were 91.29%, 5.25%, 0.23% and 3.09%, respectively, The contents of crude protein and crude ash were higher than those of Apostichopus japonicus, whereas the contents of moisture and crude fat were lower than those of A. japonicus. The total amino acids (TAA) content of Penglai sea cucumber was 53.76%, which was significantly higher than that of A. japonicus. Furthermore, the flavor amino acids (FAA) content was 25.63%, which accounted for 47.66% of TAA. The FAA contents were higher than those of A. japonicus, suggesting that Penglai sea cucumber might be more delicious than other sea cucumber species. In addition, the contents of PUFA and “DHA+EPA” were 26.47% and 12.08%, respectively and the UFA/SFA ratio was 3.19 in Penglai sea cucumber, which were higher than those in A. japonicus. The body wall of Penglai sea cucumber has great content in major and trace element, VB6, VB1, and suitable Ca/P ratio. The content of VB1 was 1.3 mg/100 g, which was higher than that of A. japonicus. In conclusion, Penglai sea cucumber bears better nutrition condition, and is a promising species for aquaculture and stock enhancement.

Abstract:The dynamic changes and diversity of bacterial communities in two types of ponds (M1: pond with sand around and netted bottom, M2: traditional soil pond) of Portunus trituberculatus- exopalaemon carinicauda polyculture in different seasons were investigated by the technology of terminal restriction fragment length polymorphism (T-RFLP) analysis based on bacterial 16S ribosomal RNA gene and cloning. The results showed that the bacterial communities in both M1 and M2 consisted of Proteobacteria, Bacteroidete, Actinobacteria, and Cyanobacteria. The composition of bacteria community changed dramatically with breeding time with various compositions in different ponds. The bacterial community in M1 is composed of Actinomycetes, Cyanobacterium and Proteobacteria, while the bacterial community in M2 included Cyanobacterium and proteobacteria, indicating that M1 was conducive to the growth of Cyanobacteria. The highest relative abundances of Bacteroidetes were in August and September in both M1 and M2, and M2 always has higher relative abundances of Bacteroidetes than M1 during the whole farming time. The bacterial community of M1 pond changed from high diversity index and stability structure to low diversity index and instability structure over breeding time, while bacterial community of M2 pond remained high diversity index in the late breeding time. PCA analysis showed that the seasonal variations of bacterioplankton were much more obvious in M1 than M2, indicating the greater ability of M2 to resist environmental change than M1. Correlation analysis results indicated that environmental factors have different effects on bacteria community of each pond water.

Abstract:The most effective way to protect wild life resources and to meet the market’s demand is artificial aquaculture. The low survival rate of sea horse juvenile due to low food intake slowed down the development of the culture industry; however, the reasons that impact feeding behavior and its metabolism of the juvenile are unclear. To address this, ten 2- or 3-day-old juveniles of Hippocampus kuda were fixed in paraformaldehyde with PBS, and its skeletal morphology of the snout tube was observed and analyzed. The tube snout’s profile and structure included metapterygoid, quadrate and symplectic, were important to juvenile’s feeding. A hole composed of metapterygoid and the end of symplectic is the smallest diameter in the snout tube, which decided the size of the feeding food. In addition, there is a crevice between metapterygoid and symplectic, which could slightly compensate the limitation in the snout tube and can pass bigger food than the smallest diameter. These observations suggest that properly increasing the size of food might enhance feeding efficiency and promote survival rate.

Abstract:The S-3685 strain, a marine bacterium producing neutral protease, was screened from South China Sea. It was identified as a Bacillus sp. based on the morphology, the biochemical characteristics, and the 16S rDNA sequencing results. This strain was gram-positive, and the spore located in the middle had ellipse or columnar shapes. The bacterial colony was round, protuberance, and milk white on the agar culture-medium. The surface of the bacterial colony was smooth and moist (30℃, 24 h). Over time the colony slightly shriveled bumps in the middle. The length was 2.4−3.2 microns. The strain grew under the pH 5.0−11.0, and could grow normally at the temperature 4−40℃. We then explored the fermentation conditions using a 250 ml shake flask. The optimum sources of carbon and nitrogen were glucose (10 g/L) and pulse flour (10 g/L) respectively, plus the beef extract (5 g/L) and the yeast extract (5 g/L). The optimum concentrations of MgSO4·7H2O, Na2CO3 and KH2PO4 were 0.2 g/L, 2.0 g/L and 1.0 g/L respectively. The optimum initial pH of the culture medium for the protease production was 7.0. The optimized culture conditions were: inoculums at 4%, broth content at 15 ml/250ml(v/v), temperature at 30℃, and culture for 72 h. After the optimization, the productivity of protease was increased by 5 times (from 850 to 4250 U/ml).

Abstract:The current in sea can maintain the water quality in the cage, but the strong current can cause serious deformation of the cage and reduce the effective volume of the cage. This study was conducted to research the reduction in flow velocity downstream from square cages in currents. The flow-velocity distribution downstream from cages was invested with four different net mesh shapes and sizes. The reduction in flow velocity was recorded using both the Particle Image Velocimetry (PIV) and Acoustic Doppler Velocimetry (ADV). The results showed that there was an obvious reduction in flow velocity downstream in the four cage models. The height of the flow-reduction region was approximately the same as the height of the cage. The flow velocity increased at the bottom of the cage. The results achieved by PIV consistent with the data recorded by ADV. The average reduction factor of the four cage models was from 0.5 to 0.8 at 0.18 m/s the incoming velocity. The reduction in flow velocity of the cage with small meshes was greater than the cage with big meshes. The reduction in flow velocity of the cage with diamond meshes was slightly greater than the cage with square meshes. The average reduction factor was not obviously impacted by the incoming velocity. The results of the vertical plane through the center of the cage by PIV were visualized by the velocity nephogram. These findings will contribute to the understanding of the flow characteristics around the square cage.

Abstract:The current study measured the contents of main nutrient components in the skin of O. keta by focusing on proteins, common amino acids, hydroxyproline, fat, vitamins, and mineral ions. The results showed that the contents were composed of 31.10% crude protein, 7.40% crude fat, 1.20% ash, 0.23% of total carbohydrate, and various delicious amino acids. There was 682.1 mg/g total amino acids in dry sample having the highest Gly content (185.0 mg/g), followed by Glu (75.8 mg/g) and then hyp (19.3 mg/g). The ratio of EAA/TAA is 22.4% and the ratio of DAA/TAA is 53.7%. The skin has rich collagen content of 214.2 mg/g based on wet weight, accounting for 68.9% of the crude protein. The content of UFA was 10.8%, and the results also indicated that the skin of O. keta was also rich in vitamin B3 (75 mg/kg) and mineral ions such as Ca, Na, Fe, Zn, etc. In summary, the skin of O. keta has high nutritional value, which is a good source for extracting collagen that is widely used in medical, food and chemical industry.

Abstract:he effects of surfactant on the voltammetric behavior of doxycycline (DOC) were investigated using conductive carbon black paste electrode (CCBPE) as working electrode. A new electrochemical method for determining DOC in aqueous solution was developed with the help of surfactant. The electrostatic interaction between the DOC molecules and the sodium dodecyl benzene sulfonate (SDBS) by self-assembled on the surface of CCBPE promoted the accumulation of the analyte. In B-R buffer solution of pH 2.0, the presence of 2.0×10–4 mol/L SDBS significantly improved the sensitivity of detection of DOC. In the presence of SDBS, the voltammetric behavior of DOC was investigated by cyclic voltammetry. An irreversible and adsorption-controlled electrode reaction occurs with 1 proton and 2 electrons participation. Under the optimum conditions, the anodic peak current of DOC is proportional to its concentration in the range of 1.0×10–7−2.3×10–5 mol/L with a detection limit of 4.5×10–8 mol/L (S/N=3). Inorganic ions do not have negative effects on the determination, while organic molecules have positive effects probably due to the competitive adsorption function. The average recoveries in the range of 97.44%−105.28% were obtained. Thus, the developed method for the determination of DOC possesses advantages such as simple operation, fast response, low detection limitation, good recovery, and repeatability.