Volume 74, 2022
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ItemEffects of vitamin E on growth and maturation in the Asian catfish (Clarias macrocephalus) at puberty( 2022)The maturation of male fish is a problematic aspect of Clarias macrocephalus and probably one of the causes of the population's disappearance in the usual places where they once abound. The present study aimed to explore feed additives to enhance its maturation from puberty. Vitamin E (VE) is essential in the reproduction of animals, including fish. A growth trial was conducted in which groups of C. macrocephalus were fed experimental diets containing graded levels of VE in the form of α-tocopheryl acetate (α-TA), namely, 0, 100, 200, 300 and 400 mg VE·kg-1 diet. After 90 days, growth and maturation were assessed, and reproductive performance was tested by conducting induced spawning and artificial fertilization. Results showed growth and nutrient utilization indices were better in groups fed diets containing VE than in the control group. Maturation indices such as GSI, gonad weight, lengths, egg diameter, and fecundity were enhanced in the VE-treated groups. Reproductive performance, such as fertilization, hatching, and larval survival rate, was enhanced in C. macrocephalus broodstock in VE-treated groups. Quantitative estimates for optimal VE dose that elicited maximal response values ranged from 202.1 to 230.0 mg VE·kg-1 diet.
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ItemEffects of salinity and alkalinity on growth and survival of all-male giant freshwater prawn (Macrobrachium rosenbergii De Man, 1879) juveniles( 2022)All-male giant freshwater prawns (AMGFPs) have been a popular crop cultivated in the Mekong Delta, Vietnam, due to their proven production efficiency compared to all-female or mixed-sex prawn cultures. However, the crucial water quality factors impacting AMGFP aquaculture efficiency have yet to be elaborately investigated. Two separate experiments were randomly arranged with three replicates to evaluate the effects of salinity or alkalinity on the growth and survival of AMGFP juveniles during the grow-out period. The results show that the prawn survival rate in the salinity range of 0–15‰ varied from 66.1 to 74.8％ and in a salinity range of 0–5‰ was relatively low compared to the range of 10-15‰; however, the difference was not significant among salinities after 90 days of culture (p > 0.05). All the prawn growth performance parameters significantly decreased with increasing salinities of 0, 5, 10, and 15‰ after 30, 60, and 90 days of culture (p < 0.05). Notably, the prawn yield did not significantly differ between salinities of 0 and 5‰ (p > 0.05), and both were significantly higher than those at salinities of 10 and 15‰ (p < 0.05) after 90 days of culture. In addition, the survival rate reached 82.5–84.4％ and did not significantly differ among alkalinities of 80, 100, 120, 140, and 160 mgCaCO3 L−1. However, the growth performance parameters and yield of AMGFPs at an alkalinity of 160 mg L−1 were significantly higher than those at lower alkalinities (80, 100, 120, and 140 mg CaCO3 L−1) after 90 days of culture. Therefore, it is recommended that a salinity range of 0–5‰ and alkalinity of 160 mgCaCO3 L−1 is optimal for the growth-out culture of AMGFP juveniles.
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ItemAutophagy genes of ATG5-ATG12 complex in response to exogenous stimulations in Litopenaeus vannamei( 2022)Autophagy plays an important role in resisting pathogens infection and environmental stress. However, there are few studies on autophagy and its regulation in Litopenaeus vannamei. In this study, the autophagy-related genes of ATG5-ATG12 complex (ATG5, ATG7, ATG10 and ATG12) were cloned and investigated on the response to exogenous stimulations in L. vannamei. Multiple sequence alignment and phylogenetic analysis of different species showed that four autophagy genes were conserved among different species. Tissue detection showed that the four autophagy genes were expressed in all tissues, and the expression level was the highest in the hepatopancreas in L. vannamei. Furthermore, the expression levels of the four autophagy genes were up-regulated significantly after stimulation with Vibrio harveyi and the virus analog poly(I:C) (p<0.05), and their peak values occurred at 24-48h. These results indicated that ATG5, ATG7, ATG10 and ATG12 may be involved in resisting pathogen infection in L.vannamei, which provided a basis for studying the molecular mechanism of autophagy in resistance to pathogen infection of L. vannamei.
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ItemHepatopancreatic transcriptome response of Penaeus vannamei to dietary ulvan( 2022)The study aimed to determine the effect of feeding dietary ulvan on some genes and pathways of Penaeus vannamei juveniles. Feeding a diet containing ulvan at 1.0 g·kg-1 resulted in differentially expressed genes (DEGs) between the treatments and the control group. Ulvan resulted in 53 DEGs with 26 up and 27-down-regulated DEGs. The DEGs were immune-related, while several affected the energy and substrate metabolic pathways. Specific genes upregulated were Glycerol-3-phosphate acyltransferase (GPAT) of the glycerolipid synthesis, centrosomal protein 120 involved in cell cycling and other activities, RNA helicase, an enzyme involved in opening up DNA molecules, ATP-binding cassette, TATA-binding protein, taurine transporter, transcriptional enhancer factor (TEF), C-type lectin among others. Down-regulated genes included gamma-crystallin, which acts as molecular chaperones; catenin alpha, which is involved in adhesion complex; dystrophin, which is involved in scaffolding for several signaling molecules; and maintenance muscle integrity, among others. Top DEGs that affected significantly important pathways include TEAD (transcriptional enhancer factor domain), GSK3B (glycogen synthase Kinase 3 beta), SLC6A1 (i.e., solute carrier Family 6 Member 1), and ADCY2, which affected signal transduction, environmental adaptation as well as the endocrine, immune, nervous, and digestive systems. In conclusion, dietary ulvan resulted in the up-regulation of immune-related DEGs, which could probably be used to adapt to unfavorable conditions and also affected some energy and substrate metabolic pathways that could potentially be used to direct the overall metabolism.
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ItemAnalysis of intestinal flora and environmental microbial diversity of Takifugu rubripes( 2022)Takifugu rubripes (T. rubripes) is marine fish rich in protein and essential amino acids. With the continuous development of T. rubripes farming, intensive aquaculture has increased the infection rate with fish diseases. To explore the relationship between environmental microbial communities and gut microbiota, we sequenced the 16s rRNA gene V3–V4 region of the microorganisms in the aquaculture water and gut flora of T. rubripes. The results indicated 934 operational taxonomic units for T. rubripes gut contents and aquaculture samples. A total of 31 phyla and 498 genera were identified. At the phylum level, except for the phylum Proteobacteria, the dominant phyla in intestinal contents were Firmicutes, Acidobacteria, and Fusobacteria. However, the dominant phyla in water were Actinobacteria, Cyanobacteria, and Patescibacteria. At the genus level, intestinal contents included Photobacterium, Arcobacter, Vibrio, and Ruminococcaceae. The water samples mainly included CladeIa, Rhodobacteraceae, Eutreptiella pomquetensis, Lentibacter, CladeIII, and PeM15. Principal component analysis showed that the microbial compositions of samples from the same source were similar. There were significant differences between the intestinal flora and water microorganisms. Therefore, the research results showed the differences between the microbial communities in the intestinal tract and aquaculture water of T. rubripes and the characteristics of the main pathogenic bacteria; this could help guide the environmental regulation and disease prevention of T. rubripes aquaculture.
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Item17α-Methyltestosterone enhances growth and reproductive performance of immature male Asian catfish (Clarias macrocephalus)( 2022)This study aimed to assess the effects of 17α-methyltestosterone (MT) on the growth and reproductive performance of male Asian catfish (Clarias macrocephalus). A total of 36 immature male Asian catfish (ABW = 125.97 g) were randomly distributed into 12 circular tanks, and fed with either the control diet (with no MT) or diets containing MT at 60 mg·kg-1, 90 mg·kg-1, or 120 mg·kg-1 for 45 days. Results showed that weight gain (WG), specific growth rate (SGR) and feed intake (FI) were significantly higher in the male catfish fed with diets containing 60 and 90 mg·kg-1 MT than in those fed with the control diet. Also, the diet attractability test revealed that the 60 and 90 mg·kg-1 MT groups significantly attracted more catfish than did the control diet; however, increasing MT to 120 mg·kg-1 reduced its attractability to the immature male catfish. MT-treated male catfish exhibited significantly heavier and significantly longer testes than male catfish fed the control diet at the termination of the feeding trial. These male catfish also exhibited significantly higher gonadosomatic indices (GSI) than catfish in the control group. Following induced spawning of nontreated female catfish and artificial fertilization of its eggs using testis preparation from the experimental male catfish at the termination of the feeding trial, results showed that testis preparations from all MT-treated males resulted in significantly higher fertilization (FR) and hatching rates (HR) of the eggs. In conclusion, incorporating MT to the diet improved both the growth and reproductive performance of the male Clarias macrocephalus. Precisely, dosages of optimal dietary MT using a quadratic model for maximal SGR, GSI, FR, and HR values were estimated to be 58.3, 75.0, 90.6, and 78.2 mg·kg-1, respectively.
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ItemIndustry-finance integration activities is beneficial to the improvement of business performance of fishery companies—Based on DEA-CCR Model and DEA-Malmquist Model( 2022)Fisheries are an essential component of the national economy. The evaluation of fishery enterprises' business performance helps reveal the fishery industry's operating efficiency and serve the fishery economy's sustainable and high-quality development. This study used the data of fishery companies with industry-finance integration on the stock market from 2012-2021 and conducted a comparative study on the business performance of fishery companies with industry-finance integration on the stock market based on the DEA-CCR model and DEA- Malmquist index method. Two main results were revealed (i) the integration of industry and finance was an effective means to improve business performance, and the financial gains from the integration of industry and finance by listed fishery companies improve the overall efficiency and total factor productivity (TFP) of enterprises. (ii) The average TFP of listed fishery companies in China is declining, and technological decline is the main reason for the decline in TFP.
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ItemMicrobial-environmental interactions reveal the evaluation of fermentation time on the nutrient properties of soybean meal( 2022)Microbial fermentation techniques are often used to improve their quality, where the keys are fermentation strains and fermentation time. This study studied the interaction between microbiota and environmental (or nutritional) factors and microbiota at different fermentation times to determine the most appropriate time, using lactic acid bacteria as fermentation strains. It can be concluded that fermentation improved the nutritional value of soybean meals. In the early stages of fermentation, debris in soybean meal highly proliferated and destabilized the microbial community, while pH and nutritional conditions played an important role in helping its stabilization. In addition, we must pay attention to the interspecific interactions of microorganisms, which makes it easy to understand how the microbial community maintains community stability. A 4-day fermentation of soybean meal with Lactobacillus is recommended.
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ItemDietary calcium requirements of bighead carp (Aristichthys nobilis)( 2022)To investigate dietary calcium requirement of bighead carp (Aristichthys nobilis), six purified diets were formulated to contain different concentrations of calcium (0.09% (control), 0.43%, 0.76%, 1.12%, 1.44%, and 1.79% of dry diets). Each diet was hand-fed to triplicate 30 fish with an average initial body weight (3.31 ± 0.09 g) for 60 days. The results showed that weight gain (WG) and specific growth rate (SGR) significantly increased when dietary calcium level was from 0.09% to 0.76% (P < 0.05). The phosphorus and calcium contents of whole fish body were highest in the 0.76% and 1.12% group, respectively (P < 0.05). The serum phosphorus content in the 1.79% group was significantly lower than those in other groups (P < 0.05). As dietary calcium content was from 0.09% to 0.76%, the activities of lipase and proteinase in the intestine had a significant increase (P < 0.05), while the glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activities were significantly decreased (P < 0.05). Based on quadratic curve model analysis with WG and WGR as the appraising criteria, the appropriate dietary requirement of calcium for the bighead carp larvae (3.31 ± 0.09 g) was 1.01% - 1.02%.
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ItemTranscriptome profiling of Penaeus vannamei hepatopancreas infected with WSSV following feeding diet containing ulvan( 2022)The present study aimed to elucidate the mechanism of protection provided by dietary ulvan as observed in previous studies. Thirty shrimps (3.35 ± 0.08 g average body weight) were stocked in six polyethylene tanks (5 shrimps tank-1, treatments were in three replicate/tank) and were fed either a diet containing no ulvan (control) or containing ulvan at 1 g kg diet-1 for 35 days at 10% body weight twice daily. At the termination of the feeding, the shrimps were subjected to a white spot syndrome virus (WSSV) challenge test via intramuscular injection of the viral inoculum. Shrimps were sacrificed after 24 h of exposure, and the hepatopancreas was excised for total RNA extraction for transcriptome profiling. Biological validation of the RNA-seq results was also performed for 10 immune-related genes (6 up- and 4 down-regulated genes). A comparison of the ulvan group with the control group revealed that 69 differentially expressed genes (DEGs) were significantly up-regulated, whereas 640 were significantly down-regulated. 184 DEGs between the control and ulvan-treated groups were classified into six KEGG categories of Metabolism (145 DEGs), Organismal systems (16), Human disease (4), Genetic Information Processing (10), Cellular Processes (2), and Environmental Information Processing (7). The 145 DEGs under Metabolism were distributed to Level 2 subcategories as carbohydrate metabolism (59 DEGs), global and overview maps (44), energy metabolism (27), and amino acid metabolism (15). All candidate immune-related genes (67) were down-regulated except for 5 genes. The validation experiment showed proportionality of gene expressions of the qPCR and of those in the assembled transcriptome, justifying the acceptability of the RNA-seq results. In conclusion, data from the present study provided mechanisms for protecting the white shrimp by dietary ulvan against WSSV infection.