ROUNDUPS

• Advances of fish muscle growth

  HE Yuhui, LI Xiang, SHI Jun

  2024,48(9):099601-099601, DOI: 10.11964/jfc.20240114344

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  Fish is a vital source of animal-based protein due to its abundant muscle content. The objective of fish aquaculture is to enhance muscle fibers hyperplasia and hypertrophy through optimal breeding conditions and technologies, thereby accelerating muscle growth and increasing the economic viability of industry. The fundamental processes of fish muscle growth involve hyperplasia and hypertrophy of muscle fibers, coupled with the ongoing fusion of muscle cells, culminating in the development of larger myotubes or thicker myofibers. Before the differentiation of myotubes into two distinct muscle fibers—white (fast) and red (slow) muscle tissues—the cells undergo gradual specilization, assembling and expressing muscle-specific proteins, including various myosin isoforms. This review summarizes the latest insights into fish muscle growth, encompassing cell proliferation, migration, differentiation, cell-cell fusion and muscle fibers formation. It also identifies key regulatory factors (pax3, pax7, myf5, myod, myog and mrf4) and the GH-IGF signaling pathway that influence muscle development. The review elucidates the transition of mononucleated muscle cells into syncytial fibers during growth and development. Notably, two novel gene orthologs, mymk and mymx, are implicated in muscle cell fusion and are conserved across vertebrate. The determinants of fusion, such as cell adhesion molecules, fusogens, and actin cytoskeletal regulators, which facilitate the formation of finger-like projections, are crucial for muscle cell fusion. This review further explores potential aquatic genetic resources for breeding to enhance muscle growth and discusses dietary approaches to improve fish meat quality. By integrating these findings, we introduce a novel perspective on muscle growth enhancement through nutritional and genetic interventions. Collectively, this review offers a comprehensive overview of aquaculture traits development, focusing on rapid growth and enhanced muscle quality.

PAPERS

• Lipid-lowering effect of PPARα activated by feed EPA and ALA in GIFT Oreochromis niloticus

  CHEN Sen, GAO Min, YANG Jiawen, CHEN Xiaoying, WU Kun, WEN Xiaobo, RONG Hua, SUN Yuping, NING Lijun

  2024,48(9):099602-099602, DOI: 10.11964/jfc.20231114238

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  Dietary fat is an essential nutrient for fish growth, yet the impact of PPARα activation by fatty acids on lipid metabolism in fish is not well understood. This study aimed to investigate the role of PPARα activation and its regulatory effects on lipid metabolism in response to fatty acids in GIFT Oreochromis niloticus using both in vitro and in vivo approaches. Primary hepatocytes from tilapia were incubated with seven individual fatty acids: oleic acid (OA), palmitic acid (PA), alpha-linolenic acid (ALA), linoleic acid (LA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), and lipid metabolism were measured. ALA, AA and EPA significantly up-regulated the expressions of key fatty acid catabolic genes such as PPARα, carnitine palmitoyltransferase 1 (CPT1) and acyl-CoA oxidase (ACO). ALA specifically up-regulated the expressions of lipolysis related genes adipose triglyceride lipase (ATGL), adipose triglyceride lipase (HSL) and fatty acid transport-related genes adipose triglyceride lipase (LPL), respectively. EPA inhibited the expression of ACC, and ALA, EPA and AA could reduce the content of triglycerides in cells. In contrast, PA and OA increased triglyceride content and the number of lipid droplets. In vivo experiments were conducted with two fatty acids, EPA and ALA, which showed distinct gene activation patterns. Six semi-purified diets varying in ALA (0.6%, 1.2%) and EPA (0.6%, 1.2%) were formulated for normal fat (7%) group, high fat (12%) group (HF) and high fat group with EPA or ALA (0.6%, 1.2%), respectively. Tilapia with an initial body weight of (3.53±0.03) g were fed these diets for eight weeks. No significant differences in growth were observed among the groups. However, body fat was significantly reduced in all four treatment groups compared to the high-fat group. As ALA and EPA content increased, the condition factor (CF), hepatosomatic index (HSI), and muscle fat index (MFI) decreased, along with serum and liver triglycerides (TG) and cholesterol. No significant differences were found in levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), superoxide dismutase (SOD), and malondialdehyde (MDA) among the groups. Notably, MDA in the liver was significantly increased in the EPA (1.2%) group, and the expression of PPARα, CPT1, ACO, ATGL and HSL was significantly enhanced with EPA and ALA supplementation. Collectively, these findings indicate that diets containing 0.6% EPA or ALA can up-regulate the expression of PPARα and its lipid metabolism-related target genes, leading to a lipid lowering effect. The study's outcomes offer valuable insights for feed formulation and fat source screening.

• Synergistic effects of dietary bile acid and taurine on growth performance, liver health and intestinal barrier of Micropterus salmoides

  HUANG Jia, RAN Xudong, LIU Xinping, HU Wei, TANG Renjun, ZHENG Juan, CHEN Yongjun, HE Yuanfa, LIN Shimei

  2024,48(9):099603-099603, DOI: 10.11964/jfc.20240214379

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  Micropterus salmoides is a significant species in China's aquaculture industry, offering considerable economic benefits. Diet and nutrition are crucial for addressing various issues in the aquaculture of M. salmoides, including growth, health and disease resistance. Bile acids and taurine are bioactive substances that participate in various biological and physiological processes in animals. To investigate the synergistic effects of bile acid and taurine in the M. salmoides diets, four isonitrogenous (46%) and isobaric (10%) experimental diets were designed respectively by adding 0.03% bile acid (BA), 0.5% taurine (Tau), and 0.03% bile acid + 0.5% taurine (BA + Tau) to the basal diet. M. salmoides, with an initial weight of (15.33±0.23) g, were reared in an indoor recirculating system for 8 weeks. The result indicated that the growth performance of M. salmoides significantly improved with the addition of bile acid and taurine, whether used separately or combined, while also reducing serum glucose (GLU), triglycerides (TG) and cholesterol (TC) levels, and activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Compared with the control group, the experimental group exhibited a significant increase in liver antioxidant enzyme activities—superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)—and a decreased malondialdehyde (MDA) levels. Additionally, mRNA expression of lycometabolic genes (gck, pklr, pygl, pck1) and lipid metabolism genes (cpt1, acaca) in liver was regulated. Additionally, it decreased liver lipid and glycogen content and notably enhanced the hepatic histomorphological structure. It significantly increased the activity of intestinal antioxidant enzymes (SOD, CAT, GSH-Px) and reduced the relative expression levels of intestinal pro-inflammatory cytokines (IL-1β, IL-8, and TNF-α). Furthermore, it elevated the relative expression level of the intestinal tight junction protein gene zo-1, and the bile acid and taurine combination notably upregulated claudin-1 and occludin-1. Moreover, the content of D-lactic acid (D-lac) and diamine oxidase (DAO) activity in serum in the bile acid group were significantly lower than those in control group (basal diet). In conclusion, supplementing feed with bile acid and taurine, either individually or in combination, enhances liver and intestinal antioxidant capacity, modulates glycolipid metabolism, boosts immune function, and fosters the growth of M. salmoides. The combination of bile acids and taurine exerts a synergistic effect on M. salmoides.

• Effects of VD₃ on survival rate and glucose metabolism ability in Monopterus albus fed a high carbohydrate diet

  LUO Tianlun, WU Shanshan, LI Jiamin, SHEN Kaikai, FANG Peng, JIANG Jiawei, PENG Mo

  2024,48(9):099604-099604, DOI: 10.11964/jfc.20240214388

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  To investigate the impact of dietary vitamin D₃ (VD₃) on the survival rate and glucose metabolism ability of Monopterus albus fed high-carbohydrate diets, healthy M. albus juveniles (17.13±0.08) g were randomly assigned into 3 groups, each with 4 replicates of 60 fish. The fish were fed diets with normal, high carbohydrate level, and high carbohydrate level supplementing with 2 000 IU/kg VD₃ (referred to as the CON, HC and HCVD₃ groups, respectively). After 8 weeks, no significant differences in growth performance or body composition were observed among the groups. However, The survival rate of HC group (82.22%) was significantly decreased, but after addition of VD3, SR (88.89%) was significantly increased, and the difference was not significant compared with CON group (90.42%). The visceral somatic index (VSI) and condition factor (CF) were significantly higher in the HCVD₃ group than in the HC group. The HC group showed the highest levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), while the HCVD₃ group had the highest serum triglyceride (TG) content. Intestinal amylase and trypsin activities were lower than in the HC group but higher in lipase. Liver glycogen content in HC group (124.45 mg/g) was significantly higher than CON group (99.55 mg/g), as were the activities of hexokinase (HK) and phosphofructokinase (PFK). In contrast, the HCVD₃ group (89.44 mg/g) had lower liver glycogen but higher PFK activity. Muscle PFK activity peaked in the HCVD₃ group. Additionally, catalase (CAT) activities in the liver and intestinal tract of M. albus were lower in the HC group, while total superoxide dismutase (T-SOD) was increased, and malondialdehyde (MDA) activities were decreased with VD₃ supplementation. The HCVD₃ group also showed significantly higher relative expression levels of intestinal proinflammatory cytokines (IL-1β, MyD88), anti-inflammatory cytokines (IL-10) and intestinal compact linking protein genes (ZO-1, ZO-2, Claudin-12) than the HC group. In conclusion, a high carbohydrate diet reduced the survival rate, increased liver glycogen accumulation, reduced antioxidant capacity, and impaired intestinal health in M. albus. Supplementation with 2 000 IU/kg VD₃ mitigated these effects, improving survival and enhancing carbohydrate utilization in fish fed a high-carbohydrate diet. This study provides foundational insights and guidance for glucose metabolism regulation and the artificial feed formulation for M. albus.

• Effects of arachidonic acid (ARA) on reproduction, immunity, and lipid metabolism of Penaeus vannamei broodstocks

  ZHONG Xiao, XU Bin, LIU Jiaxin, WANG Yilei

  2024,48(9):099605-099605, DOI: 10.11964/jfc.20231214295

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  Pacific white shrimp (Penaeus vannamei) is a staple in aquaculture due to its rapid growth cycle, adaptability to both freshwater and saltwater, broad temperature tolerance, minimal nutritional needs, and high meat yield. It is recognized the Chinese shrimp (P. chinensis) and black tiger shrimp (P. monodon), as one of the three most important shrimp species for global aquaculture. The industry's sustainable growth hinges on the development of superior feed, breeding of high-quality stocks, and the provision of premium seedlings to enhance the reproductive performance and quality of the Pacific white shrimp's offspring. The research investigates the impact of arachidonic acid (ARA) on the reproduction, immunity, and lipid metabolism of the Pacific white shrimp's broodstock, offering insights for selective breeding and feed formulation. Males at six months of age and unilaterally eyestalk-ablated female shrimps were selected to reflect actual breeding practices. They were randomly assigned to five groups, with females and males reared separately. The groups were fed with different levels of ARA (0.03%, 2.70%, 4.99%, 10.63%) in pelleted feed (designated as Z1-Z4) and a control group with natural feed (clam worms) (designated as Z5). Findings indicate that the weight gain rate (WG) of female shrimps on the pelleted feed was significantly superior to the control. The hepatopancreatic index (HSI) of the broodstock showed an initial increase followed by a decrease with escalating ARA concentrations. At an ARA concentration 4.99%, optimal hepatopancreatic development, peak hatching rate, and superior larval yield and quality were observed, along with heightened expression of genes pivotal to ovarian development (Vtg, VtgR, VASA, and FAMeT2). This ARA level also modulated lipid metabolism in the female hepatopancreas, enhancing the expression of genes associated with lipid processing and transport (PL, SREBP and FATB), thereby influencing the fatty acid profile of fertilized eggs. Notably, it elevated the functional fatty acid DHA content and adjusted the ratios of ∑n-3 and ∑n-6 polyunsaturated fatty acids (PUFA). Due to the antagonistic relationship between reproduction and immunity, this ARA concentration led to a reduction in oxidant stress and non-specific immune responses. In conclusion, different ARA levels in feed significantly influence the growth, reproductive success, immune function, and lipid metabolism of the Pacific white shrimp's broodstock. To prioritize reproductive performance, an ARA content of 4.99% in the broodstock feed is recommended for its positive effects on ovary development and larval production, offering valuable guidance for the ARA application during the breeding phase of the Pacific white shrimp.

• Expression patterns of tyrosinase, peroxidase and alkaline phosphatase genes during larval shell formation of the mollusk Haliotis discus hannai

  YIN Xiaowen, TAN Sujian, XU Fei, HUAN Pin, LIU Baozhong

  2024,48(9):099606-099606, DOI: 10.11964/jfc.20240214355

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  To elucidate the mechanisms underlying larval shell development, this study examined the morphological traits of shell field in the Pacific abalone Haliotis discus hannai using scanning electron microscopy and assessed the expression profiles of five candidate genes related to shell formation, including tyrosinases gene (Hdi-Tyr1, Hdi-Tyr2), peroxidases gene (Hdi-Prx1, Hdi-Prx2), and alkaline phosphatase gene (Hdi-Alp). The results revealed that the shell field consisted of at least three distinct cell populations displaying a characteristic "rosette" pattern. Expression of the Hdi-Tyr1 and Hdi-Tyr2 displayed U-shaped patterns in the shell field of trochophore larvae, and their mRNA were identified in columnar cells at the mantle edge of veliger larvae. However, Hdi-Alp, Hdi-Prx1 and Hdi-Prx2 were exclusively expressed in the prototroch and head of the larvae and showed no detectable expression in the shell field. These findings indicate that Hdi-Tyr1 and Hdi-Tyr2 may be involved in the larval shell formation of H. discus hannai, whereas Hdi-Prx1, Hdi-Prx2 and Hdi-Alp are not involved in this process. These insights provide a foundation for subsequent research into the shell development mechanisms and genetic improvement of shell-related traits in mollusks.

• Sequence characteristics of V-ATPase-d gene in Pinctada fucata martensii and its relationship with low temperature tolerance

  LAI Zhuoxin, SONG Xinlin, PAN Ruozhe, TAN Youxuan, WANG Qingheng

  2024,48(9):099107-099107, DOI: 10.11964/jfc.20220313351

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  V-ATPase plays an important role in biological response to various environmental stress, in order to explore the role of V-ATPase in the low temperature adaptation of Pinctada fucata martensii, the V-ATPase-d gene of P. fucata.martensii was identified, and the changes in the expression of Pm-V-ATPase-d under low temperature stress were analyzed. Screening and comparative analysis of the gene in the low temperature resistant breeding line (R) F₃ and Beibu Gulf wild population (W) SNP loci in the exon region. Sequence analysis showed that Pm-V-ATPase-d has a total length of 1 473 bp and open reading frame (ORF) of 1 140 bp, encoding 379 amino acids, with a typical ATP domain, Pfam vATP-synt_AC39. The results of motif analysis and tertiary structure prediction showed that Pm-V-ATPase-d was highly conserved, and it clustered with Crassostrea gigas in the phylogenetic tree. Whole tissue fluorescence quantitative results showed that Pm-V-ATPase-d was expressed in all the tested tissues, and the expression level was higher in hepatopancreas, gonads and gill tissues (P<0.05). Under low temperature stress, the expression level of Pm-V-ATPase-d gene increased first and then decreased with the extension of time, and the expression level of the low temperature group was significantly higher than the control group(P<0.05), indicating that Pm-V-ATPase-d may be involved in the response of P. fucata martensii to temperature stress. The SNP analysis of the exon region of Pm-V-ATPase-d resulted in a total of 35 SNPs, which 34 were synonymous mutations, only one site was a non-synonymous mutation, and 26 SNPs were significantly different between genotypes and alleles in W and R populations(P<0.05), the results of haplotype linkage disequilibrium analysis showed that the Pm-V-ATPase-d gene SNPs could form 6 haplotype blocks and 14 haplotypes, the haplotypes GAAT, CGC, TC, TG and AG were significantly correlated with low temperature resistance traits of P. fucata martensii (P<0.05). These research data indicate that Pm-V-ATPase-d may be a candidate gene involved in regulating the adaptation to low temperature of P. fucata martensii. This study can provide a research basis for the adaptation mechanism of P. fucata martensii to low temperature. The SNPs and haplotypes associated with low temperature resistance traits can be used in molecular assisted breeding.

• Taxonomy and morphological comparison of larva and juvenile stages in the genera of Lobianchia and Idiolychnus

  LIU Shufang, LIU Qiaohong, WANG Huan, LI Ang, AN Changting, WAN Ruijing, ZHUANG Zhimeng

  2024,48(9):099108-099108, DOI: 10.11964/jfc.20230914147

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  Globally, the fish genera Lobianchia Gatti, 1904 and Idiolychnus Nafpaktitis et Paxton, 1978 belong to the Myctophidae family, within the Myctophiformes order. The genus Lobianchia includes two species: Lobianchia dofleini (Zugmayer, 1911) and Lobianchia gemellarii (Cocco, 1838) , while the genus Idiolychnus comprises only one species Idiolychnus urolampus (Gilbert et Cramer, 1897) . Currently, there are limited reports on Lobianchia and Idiolychnus in Chinese waters, with adults, larvae and juveniles of Lobianchia gemellarii documented in the waters off eastern Taiwan, and larvae and juveniles identified as Lobianchia gemellari and Lobianchia urolampus collected from the Kuroshio Current region off the East China Sea. To further elucidate the taxonomy and early developmental morphology of these species, an identification key for the these two genera Lobianchia Gatti, 1904 and Idiolychnus Nafpaktitis et Paxton, 1978 was compiled. Following a review of the data and samples from the aforementioned surveys conducted from June to July 1984 (summer) and December 1984 to January 1985 (winter), the larvae and juveniles previously identified as L. gemellari and L. urolampus, were corrected to L. gemellarii (Cocco, 1838) and I. urolampus (Gilbert et Cramer, 1897), respectively. Additionally, the early developmental morphology of L. gemellarii post-larva of 5.10 mm in BL and the I. urolampus juvenile of 6.80 mm in BL were described respectively. The developmental morphological characteristics of larvae and juveniles of L. dofleini, L. gemellarii, and I. urolampus juvenile were discussed. Upon comparison, the aliform pectoral fins of Lobianchia and Idiolychnus larvae and juveniles represent a distinctive morphological feature. A comparative analysis of melanophore shape, quantity, and distribution on the body surface of larvae and juveniles from these two genera was performed. As analyzed, melanophores shape and quantity, which conceivably vary with habitats, exhibit species-specificity. Thus, melanophores shape and quantity can be used as morphological characteristics for species identification. The developmental sequence and distribution of the branchiostegal organ (Br) in Lobianchia and Idiolychnus larvae and juveniles were elucidated. Analysis of the distribution data of Lobianchia and Idiolychnus larvae and juveniles across various oceans suggests that Lobianchia dofleini larvae and juveniles are rarely found in the Northwest Pacific. Spawning stocks of Lobianchia gemellarii in the Kuroshio Current region off the East China Sea reproduce during winter, spring and summer, but the specifics of their spawning habits remain unclear. This study contributes to understanding of the morphology and ecology of lanternfishes early life stages and offers scientific evidence for the utilization and management of these small-sized marine fish resources.

• Feeding and migration of Todarodes pacificus in the East China Sea based on the stable isotopic information of gladius

  WANG Rui, LU Huajie, CHEN Jing, OU Yuzhe

  2024,48(9):099309-099309, DOI: 10.11964/jfc.20220213348

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  Todarodes pacificus, a significant warm oceanic cephalopod species, is relatively well understood in terms of population structure, age, growth and reproduction. However, the species' migration patterns and feeding habits remain elusive due to limitations in artificial breeding techniques and the shortcomings of stomach contents analysis. Further research is essential to elucidate the migration path and feeding habits of T. pacificus for effective resource management. This study focused on the the proostracum of gladius of T. pacificus caught collected from the East China Sea in 2018 and 2019. The proostracum was sequentially sectioned, and the carbon and nitrogen stable isotope ratios of fragments were measured. Using trophic niche and stable isotope sequence, we examined the migration and feeding behaviors of T. pacificus across its life history over two years and preliminarily explored the reasons for interannual variations in these behaviors. The trophic niche analysis revealed distinct and non-overlapping ranges for T. pacificus in 2018, while in 2019, the ranges were similar and overlapping [2018: total area (TA) 3.11‰², standard ellipse area (SEAc) 0.81‰²; 2019: TA 3.51‰², SEAc 0.77‰²]. The stable isotope sequence indicated significant changes in the values for T. pacificus when the gladius proostracum reached 120 mm from the distal end in both years. On the population level, the average δ¹³C and δ¹⁵N values of T. pacificus from each spawning ground population in 2018 were positively correlated with gladius growth, while in 2019, only the average δ13C values showed such a correlation. Statistical tests revealed significant differences in the average δ¹³C values between 2018 and 2019 (t-test, F=1.104, P<0.01), but no significant differences in average δ¹⁵N values (t-test, F=3.903, P>0.05). The analysis indicated that T. pacificus individuals in 2018 originated from various spawning grounds, and all the individuals of T. pacificus in 2019 came from the same spawning grounds, whereas in 2019, they all came from the same grounds. In both years, the T. pacificus began migrating to low latitudes and coastal waters once the gladius proostracum reached 120 mm, with prior movements confined to the vicinity of spawning ground. The broader migration range in 2019 may be attributed to the El Ni?o event. As T. pacificus individuals grew and migrated, their trophic level increased in 2018, whereas in 2019, it remained relatively stable. This study demonstrated the utility of continuous gladius sampling for analyzing the feeding and migration of T. pacificus, providing a scientific foundation for future research on T. pacificus.

• Fish species diversity in the Zhongjieshan Islands based on environmental DNA metabarcoding

  ZHONG Lanping, GAO Tianxiang, ZHANG Haobo, CHEN Zhi, WANG Xiaoyan

  2024,48(9):099310-099310, DOI: 10.11964/jfc.20220613527

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  Rocky reef habitats are critical for supporting exceptionally high fish species diversity, a vital element of biodiversity. However, monitoring fish species in these habitats using traditional fisheries resource survey methods poses significant challenges. Therefore, there is an urgent need to develop sensitive and efficient methods for biodiversity monitoring. Four sampling stations were strategically selected around the Miaozihu Islands within the Zhongjieshan archipelago, and surface seawater samples were collected across four seasons (February, May, August and November in 2019). The spatial and temporal distribution of fish was analyzed using environmental DNA metabarcoding technology. The findings revealed a total of 37 fish species across 10 orders 26 families 36 genera. The seasonal abundance of fish species followed a trend of summer >winter > autumn > spring. Remarkably, only 2 fish species were observed in all four seasons, representing approximately 5.41% of the total species count, while 54.05% of the species were detected in a single season only. The non-metric multidimensional scaling (NMDS) analysis and the analysis of similarities (ANOSIM) test indicated significant variation in fish composition among seasons (P<0.05), but not among stations. The fish community's uniformity remained relatively stable. Although the diversity and richness indices did not exhibit significant differences among stations, they peaked in summer and troughed in spring. Overall, the distribution of fish in the coastal waters of the Zhongjieshan Islands is significantly influenced by the seasonal changes rether than station locations. This study introduces an innovative, environmentally friendly approach to fish diversity assessment in marine environments akin to those of the Zhoushan islands and reefs, offering valuable technical insights for the management and conservation of fisheries resources.

• Changes of phytoplankton community structure in Litopenaeus vannamei culture ponds and outer river

  PAN Fan, JIANG Min, WU Hao, TANG Yan, XI Wenshuang, YE Junqiang, YU Zhongli

  2024,48(9):099111-099111, DOI: 10.11964/jfc.20220313405

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  This study aimed to elucidate the dynamics of phytoplankton community structure in Litopenaeus vannamei culture ponds, compare them with those in surrounding waters, and explore the correlation between phytoplankton and environmental factors. Samples were collected from the aquaculture ponds and the adjacent river of a L. vannamei farm in Fengxian District, Shanghai. Multivariate analysis was employed to examine the relationships between phytoplankton and environmental parameters. The study identified 67 genera across 7 phyla in the ponds, with Chlorophyta predominating at 51%. The dominant genera included 28 genera from 5 phyla, with Chlorella being the most prevalent in Bacillariophyta (F=1.0). The overall average phytoplankton density was 1.09×10⁷ ind/L, with Chlorophyta, Cyanophyta and Bacillariophyta contributing 47%, 30% and 11%, respectively. Positive correlation were observed between the phytoplankton community structure and levels of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD). In the adjacent river, 7 phyla and 56 genera were detected with Chlorophyta account for 46%, among which 6 phyla and 26 genera were dominant with Cryptococcus and Cryptomonas being the dominant genera. The average phytoplankton density was 1.18×10⁵ ind/L, with Cryptophyta, Bacillariophyta and Chlorophyta comprising 46%, 27% and 13%, respectively. The river's phytoplankton structure was primarily influenced by the abundance of colonies and rotifers. The pond's phytoplankton density was significantly higher and more complex than that of the river, with Microcystis blooms posing a risk to the healthy of L. vannamei during September and October. This necessitates close monitoring of TN, TP, and organic matter levels. The study thus highlights the differences in phytoplankton community structure between shrimp culture system under artificial intervention and natural ecosystem.

• Structure of olfactory epithelium and evolution of V1Rs gene family in nine fish species

  SONG Chen, Lü Maolin, ZHANG Zhengwei, GAO Zexia, LIU Han

  2024,48(9):099112-099112, DOI: 10.11964/jfc.20230814123

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  Olfaction plays an important role in the survival and reproduction of fish, as it can perceive and identify thousands of different odor molecules, which help fish to carry out life activities such as feeding, reproduction, migration and avoidance of enemies. The ability of V1Rs to recognize pheromones plays an important role in animal reproduction and mate recognition. To investigate the differences in the structure of olfactory epithelium (OE) and the evolution of vomeronasal type-1 receptors (V1Rs) in different fish species, this study compared the structural characteristics of the OE of nine fish species based on histological studies. The sequence, protein structure and evolution of the V1Rs family in these nine fish species were identified and analyzed using comparative genomics and bioinformatics. Additionally, tissue expression patterns of the V1Rs in male and female Misgurnus anguillicaudatus were investigated by qRT-PCR. The results revealed that six species of Cypriniform fish have G-type olfactory plates types, while Siluriform fish have H-type, and Perciform fish have both F-type and G-type. There is a significant variation in the number of olfactory plates among the nine fish species studied, for example, Micropterus salmoides has only seven olfactory plates while Pelteobagrus fulvidraco has eighty. The study identified a total of 58 complete V1Rs genes, divided into six subtypes (V1R1, V1R2, V1R3, V1R4, V1R5, V1R6). Each of the nine fish species genomes contains one V1R1 and one V1R2 gene; however, the genome of the Culter alburnus lacks V1R3 and V1R4 genes, while the Siniperca chuatsi is missing the V1R5 gene. Additionally, the Megalobrama amblycephala, P. fulvidraco and C. alburnus each have two copies of the V1R5 gene. The results of qRT-PCR showed that all seven V1Rs genes were significantly highly expressed in the olfactory epithelium (OE) of both female and male M. anguillicaudatus compared with the control group (muscle tissue) (P<0.05), except for V1R3b which did not show significant expression differences between OE and muscle tissue. Furthermore, there was lower expression in the brain and beard tissues with no significant difference compared to the control group (P>0.05). However, there was a significant difference in gonadal tissues between male and female M. anguillicaudatus. Specifically, V1R1, V1R4, V1R5 and V1R6 were significantly higher in the testis than in the ovary, whereas the V1R3b was significantly higher in ovary than in testis, V1R2 and V1R3a were not significantly different in male and female M. anguillicaudatus. This study not only elucidates the morphological and histological structure of OE and the evolutionary differences of V1Rs in different fishes, but also provides a foundation for further investigation into the mechanisms and roles of fish olfactory mate recognition and the functional aspects of V1Rs genes.

• A preliminary study on the acoustic deterrence system at Xianghe fishway in Xiang River, a tributary of the Yarlung Zangbo River

  LI Jiaxin, LI Xiaobing, BAI Yanqin, SHI Xiaotao, ZHANG Zhan, NIMA Danzeng, DA Wa, YANG Ji, LI Xinyu, SUN Pan, WANG Yan, LIU Guoyong

  2024,48(9):099713-099713, DOI: 10.11964/jfc.20240114345

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  Abstract:

  Acoustic deterrence system (ADS) are pivotal for fish attraction and protection, holding considerable value in fish conservation efforts. Despite this, Chinese research on ADS has predominantly centered on identifying sounds sensitive to fish in laboratory settings, with a dearth of practical engineering studies. This study aimed to determine if sound-driven fish technology could augment fish passage in field conditions. Underwater speakers were strategically positioned at upstream river channel near the entrance of fishway 2^# in the Xianghe River, a Yarlung Zangbo River tributary, broadcasting alligator sinensis predator sounds (Alligator sinensis) on a continuous 24-hour loop. The negative phonotaxis behavior of target fish species (Schizopygopsis younghusbandi; Ptychobarbus dipogon and Triplophysa stoliczkai) was monitored as they traversed the Xianghe River's hydrological hub, employing a Passive Integrated Transponder (PIT) system. To account for the influence of hydrological and environmental factors on this behavior, a multiple-factor logistic regression model was developed. The optimal model was selected based on Akaike Information Criterion (AIC), pinpointing the critical factors influencing fish negative phonotaxis. Findings indicated that: ① the experimental group's fishway entry rate significantly exceeded that of the control group (P<0.05); ② sound exposure and the discharge at fishway entrance 2^# were pivotal in affecting fishway passage rate (P<0.05); ③ post-sound activation, the entry rates for S. younghusbandi and P. dipogon markedly surpassed that of T. stoliczkai (P<0.05); ④ during the study, the flow rate at the fishway entrance 2^# between 0.81-1.32 m³/s, with a negative correlation observed between flow rate and fishway passage rate (P=0.007). Excessive flow rate were found to diminish fishway passage rates. decreased with the increase of fishway flow rate. This research demonstrates that ADS can deter fish from hazardous zones like power station tailwaters while enhancing the likelihood of fish entering fishways in practical engineering applications. This study seeks to offer scientific foundation and reference for the engineering implementation of ADS and the refinement of ecological dispatching at hydroelectric stations.