Volume 74, 2022
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ItemThe effect of Artemia nauplii (Artemia franciscana) enriched with different commercial products on the growth performance of the larvae of freshwater angelfish, Pterophyllum scalare (Lichtenstein, 1823)( 2022)The present study was planned to determine an optimum live-feeding protocol for angelfish larvae (Pterophyllum scalare). Larvae with an initial weight of 0.10 mg, a length of 4.5 mm, and a depth of 1 mm were reared on three different feeding regimens for 30 days. All experimental larval groups were fed Artemia nauplii from the end of the yolk-sac resorption. The control treatment (Group I) was maintained on Artemia nauplii on days 14-28, and on Artemia nauplii + dry feed on days 29 and 30. Group II was reared with Artemia nauplii enriched with Algamac 3050 on days 14-28 and with dry feed + Artemia nauplii enriched with Algamac 3050 on days 29 and 30, whereas Group III was fed with Artemia nauplii enriched with Red Pepper on days 14-28, and with dry food + Artemia nauplii enriched with Red Pepper on days 29 and 30. The highest weight (37.8±0.51 mg) and length (15.8±0.35 mm) were determined in Group II with significant differences from the control group (p<0.05). However, enrichment treatments were comparable in terms of growth performance (p>0.05). The survival rate of the larvae in the treatments varied between 70-75% without significant differences (p>0.05). Overall, the study results suggest that a feeding protocol for angelfish larvae with the administration of Artemia nauplii during the first two weeks after hatching and then enriched Artemia with Algamac 3050 over the following 14-28 days followed by a gradual weaning onto dry feed.
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ItemTranscriptome analysis reveals the molecular basis of the response to acute hypoxic stress in blood clam Scapharca broughtonii( 2022)Hypoxia tolerance and adaptive regulation are important for aquatic animals, especially for species with poor mobility, such as most bivalves. Previous studies have confirmed that the blood clam Scapharca broughtonii has strong hypoxia resistance. However, the molecular mechanism supporting its hypoxic tolerance is still largely limited. To further screen the genes and their potential regulation of hypoxia tolerance, the transcriptome changes of S. broughtonii after acute hypoxic stress were explored by RNA sequencing. In this study, the average value of Q30 is 92.89%, indicating that the quality of sequencing is relatively high. The Unigenes obtained were annotated using four databases, namely Interpo, KEGG, Swisspro and TrEMBL. The annotation rates in these four databases were 71.82%, 75.95%, 92.98%, and 79.26%, respectively. And also, there were 649 DEGs in group B (dissolved oxygen (DO) of 2.5 mg/L) compared with group D (DO of 7.5 mg/L), among which 252 were up-regulated, and 397 were down-regulated. There were 965 DEGs in group A (DO of 0.5 mg/L), 2.5 mg/L, and 7.5 mg/L, compared with group B, among which 530 were up-regulated, and 435 were down-regulated. Meanwhile, there were 2,040 DEGs in group A compared with group D, among which 901 were up-regulated, and 1,139 were down-regulated. The main metabolic-related pathways of KEGG enriched in this study included Insulin secretion, Insulin signaling pathway, MAPK signal transduction pathway, and PPAR signaling pathway. These pathways may be critical metabolic pathways to solve energy demand and rebuild energy balance in S. broughtonii under hypoxic conditions. This study preliminarily clarified the response of S. broughtonii to hypoxia stress on the molecular levels, providing a reference for the following study on the response laws of related genes and pathways under environmental stress of S. broughtonii.
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ItemEffect of Vitamin B Complex and Phosphorus on Stress Resistance and Phosphorus Uptake in Barramundi( 2022)Barramundi, the Asian sea bass (Lates calcarifer Bloch 1790), is a valuable aquaculture commodity, but seed survival is generally low. This study used a completely randomized design (two factors; 16 treatments; 3 replicates) to examine the effect of adding vitamin B complex and phosphorus to the rearing media on the survival, stress resistance, and phosphorus content of barramundi larvae. Barramundi larvae aged two days were stocked at a density of 25 fish L-1 in 40 L green plastic basins (30 L water) and reared for 30 days with natural feed (Chlorella and rotifers). The factor I was vitamin B complex with 4 levels: 0, 75, 150, and 225 mg L-1. Factor II was phosphorus with four levels: 0, 0.5, 1.0, and 1.5 mg L-1. Commercially available B vitamin complex and phosphorus mineral supplements were dissolved in water and added to the larval-rearing media. Analysis of variance showed that the combination of vitamin B complex and phosphorus treatments had a significant effect (P < 0.01) on survival, stress resistance, and phosphorus uptake. Survival and phosphorus content in barramundi larvae were highest with a combination of 150 mg L-1 vitamin B complex and 1.0 mg L-1 phosphorus and lowest in control (0 mg L-1 of both additives).
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ItemHematological parameters of red tilapia (Oreochromis sp.) fed lemongrass essential oil (Cymbopogon citratus) after challenge with Streptococcus agalactiae( 2022)The study involved feeding lemongrass essential oil (LEO) supplements to red tilapia (Oreochromis sp.) at concentrations including Control - 0 mg, T1 – 200 mg, T2 – 300 mg, and T3 – 400 mg per kg of feed. The research investigated changes in hematological (HCT, Hb, RBC, WBC & thrombocytes) and erythrocyte’s morphological (major/minor axis; perimeter, and area of erythrocyte) parameters before infection, 5- and 10-days post-infection (DPI). According to analytical findings, a diet containing LEO enhanced the synthesis of both erythrocytes and leukocytes in the peripheral blood of red tilapia after 20 days of being used. Therefore, the indicators of this group of fish showed better performance than those that did not use LEO supplement five days after bacterial infection. Fish fed 200 mg/kg of LEO after being challenged with S. agalactiae for ten days showed an improved effect on red blood cell production. White blood cells decreased at all concentrations because of citral’s immunomodulatory properties.
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ItemPreliminary screening, identification and biological characteristic analysis of Bacillus probiotics isolated from Cynoglossus semilaevis( 2022)To screen local probiotic strains to promote antibiotic-free farming, two potential probiotic strains (S3, S5) were recognized among 89 cultivable bacterial strains isolated from the intestine of healthy Cynoglossus semilaevis. The two potential probiotic isolates were analyzed in terms of their morphology, physiology, biochemistry, the similarity of 16S rDNA sequences, growth characteristics, enzyme production capacity, bacterial antagonism, and safety in C. semilaevis. The results revealed that the bacterial morphology and physiological and biochemical characteristics of S3 and S5 were similar to those of Bacillus subtilis. The 16S rDNA sequences had 99.9 % similarity to that of Bacillus subtilis MH 145363.1. Therefore, S3 and S5 were identified as B. subtilis. In addition, we found that S3 and S5 had a strong ability to secrete amylase, protease, and lipase. During the safety tests of S3 and S5 in C. semilaevis with high concentrations, C. semilaevis in immersion, injection, and feeding groups remained in good condition without falling ill or dying. Moreover, we found that S3 and S5 exhibited superior growth at 25~50℃, salinities of 10 to 40, and pH values of 5 to 9. Furthermore, S3 and S5 had significant bacteriostatic activity against Vibrio anguillarum, Aeromonas salmonicida, and Shewanella algae, which are the main pathogenic bacteria of mariculture fish. In summary, S3 and S5 showed superb inhibition of the pathogenic bacteria of marine fish, rapid growth, eurythermal and euryhaline features, and suitability for the intestinal environment of C. semilaevis. Thus, strains S3 and S5 have excellent commercial development potential. These results provide a basis for ecological disease prevention strategies and are also valuable for developing and utilizing probiotics.
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ItemTranscriptome response of pubertal male Clarias macrocephalus to dietary 17α-methyltestosterone( 2022)We studied the mechanism of the effects of 17α-methyltestosterone (MT) on previously reported enhanced growth and maturation of the Asian catfish Clarias macrocephalus. A total of 18 pubertal male (3 fish·tank-1) catfish (ABW=125.97 g) were stocked into six experimental circular tanks and fed with a basal diet (control) or a basal diet containing 60 mg MT kg-1 diet for 90 days. At the termination of the experiment, livers were excised, and total RNA was extracted, evaluated, and reverse transcribed to cDNA. Six libraries of cDNA (3 for the control and 3 for the MT-treated group) were subjected to bioinformatics. Differentially expressed genes (DEGs) were identified using similarity scores of the de novo assembled transcript with those in the seven public databases. There were 141 up- and 72 down-regulated DEGs, mostly belonging to uncharacterized/not yet identified proteins. Thus, DEGs in the top enriched KEGG pathways were used to characterize the effects of MT. Upregulated DEGs included tyrosine hydroxylase (TH), Cytoplasmic Polyadenylation Element Binding (CPEB), Fas-associated death domain (FADD), Major Histocompatibility Complex class 1 (MHC-1), other immune-related genes, among others. Down-regulated DEGs included Cytochrome P450 family one subfamily A member 1 (CYP1A1), Alternative oxidase (AOX), UDP-glycosyltransferase (UGT), Acyl-CoA Synthase Bubblegum Family Member 1 (ACSBG), Stearoyl-CoA Desaturase (SCD), among others. In conclusion, MT-treated male Clarias macrocephalus exhibited up-regulation of pathways protecting cellular conditions like cell proliferation, survival, development and homeostasis processes, for development and homeostasis processes. MT also affected changes in bile acid production and the inhibition of the production/conversion of testosterone. MT resulted in the down-regulation of a serotonergic system that possibly affected gonadal development, inhibition of the retinoid enzyme that would otherwise diminish the full effects of MT or its metabolite, and inhibition of the formation of estrogen, leading to down-regulation of several estrogen-related KEGG pathways. The results provide valuable information about the key genes for use as biomarkers of maturation and reproduction for the Asian catfish and contribute to our understanding of the molecular mechanisms and regulative pathways behind these two processes in fish.
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ItemEffects of Glyphosate-Resistant Genetically Modified Soybean on Blood Biochemical Indexes, Hepatopancreatic Antioxidant Capacity and Tissue Morphology of Cyprinus carpio( 2022)The juvenile carps (Cyprinus carpio) were fed diets with four protein sources (15% and 30% glyphosate-resistant genetically modified (GM) named GM 15 and GM 30, respectively, and 15% and 30% non-genetically modified (NGM) soybean named NGM 15 and NGM 30) for 180 days. Results showed that alkaline phosphatase (ALP) activity for the GM30 group was significantly lower than that of the NGM30 group. The activity of glutathione peroxidase (GSH-Px) in the hepatopancreas of carp for the GM30 group was significantly higher than that of the NGM15 group (P<0.05). And the content of malondialdehyde (MDA) for the GM30 group was higher than that of the NGM30 group during the whole culturing process (P<0.05). The activity of catalase (CAT) for the GM30 group was significantly lower than that of the NGM30 group during 60 days and 180 days (P<0.05). While no significant differences were observed in the growth indexes, organ indexes, and muscle nutritional components of carp among the four groups (P>0.05). This study indicates that it may aggravate the damage degree of intestinal epithelial cells of carp and more easily cause liver cell damage in the short term when the amount of GM soybean in the feeds was 30%. Therefore, higher glyphosate-resistant GM soybean may have adverse effects on the carp's serum, intestinal, and hepatopancreas and considerably reduce the hepatopancreatic carp's antioxidant capacity.
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ItemAntibacterial characterization of Bacillus velezensis LG37 and mining of genes related to biosynthesis of antibacterial substances( 2022)Bacillus velezensis LG37 secretes various antibacterial substances and inhibits the growth of other bacteria. Here, we analyzed the antibacterial characteristics and the screening and verification of genes related to the synthesis of the antibacterial substance of LG37 by antibacterial activities experiment, Local BLAST+, and RT-PCR. LG37 was isolated from aquaculture water and preserved in our laboratory. The phylogenetic tree was used to analyze the genetic relationship between LG37 and the bacteriostatic test indicator strain. LG37 had a more substantial inhibitory effect on closely related strains, while the inhibitory effect on the more distantly related strains was weak. Combined with the results of genome sequencing, the ribosomal peptide (RP) bacteriocin gene and non-ribosomal peptide synthetase (NRPSs) related gene clusters were screened and analyzed. A total of six gene-coding RP bacteriocins and two genes coding surfactins and fengycin A NRPSs gene cluster were screened. Local BLAST+ analysis revealed a total of 11 NRPSs gene clusters. The active expression of the NRPSs and RP encoding genes was further validated by RT-PCR. The findings revealed various genes and gene clusters encoding RP bacteriocins and NRPSs in B. velezensis LG37. The bacterium is potentially valuable in diverse applications in aquaculture.
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ItemThe evaluation of ammonia tolerance in introduced and local Pacific white shrimp, Litopenaeus vannamei, populations in China( 2022)The white shrimp, Litopenaeus vannamei, is one of the most valuable commodities in the global seafood trade. Affected by high-density farming environments, ammonia accumulates in shrimp cultures and has a strong toxic effect, resulting in poor shrimp survival and poor immune function and metabolism. We selected six different populations of L. vannamei from Xing Hai No.1 (A and B), CHAI, Sy Aqua, PRIMO, and a second-generation Sy Aqua-PRIMO hybrid population (SP). The shrimps (3.24 ± 0.71 cm body length) were exposed to ammonia (24 h, 48 h), followed by recovery (R48 h, R96 h) to assess the tolerance of different populations. The survival rate (SR), immune-related enzymes (superoxide dismutase SOD, catalase CAT, and Glutathione peroxidase GSH-PX), Malondialdehyde (MDA), and metabolism (glutamate dehydrogenase GDH, glutamine synthetase GS, and aspartic acid transaminase GOT) and were measured at different populations under acute ammonia stress. Multiple comparisons of the ammonia resistance index from six populations showed that the expression of these indicators varied among the populations. The degree of lipid peroxidation in the Sy Aqua and PRIMO was significantly higher than in the other populations (P < 0.05), and the ammonia metabolism index was poor. The GDH and GOT genes for the Xing Hai No.1 (A) were higher than for the other populations. Mortality and physiological indicators recovered to varying degrees for all experimental populations following 96 h of ammonia relief, whereas the Sy Aqua and PRIMO showed a noticeable lag. These results indicated that the immunity and metabolic capacity of Xing Hai No.1 (A) might be higher than those of Sy Aqua and PRIMO. These data could have value in developing future scientific breeding schemes and in the sustainability of shrimp farming.
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ItemEmbryonic Development of Black Neon Tetra Hyphessobrycon herbertaxelrodi Géry, 1961( 2022)The current study described the embryonic development stages of black neon tetra (Hyphessobrycon herbertaxelrodi), an economic ornamental fish. We characterized the stages of the zygote, cleavage, blastula, gastrula, segmentation, pharyngula, and hatching occurring during embryogenesis, which emphasizes changing spectrum of the main development processes from fertilization to incubation. The findings were put forth and photographed by examining live embryos under microscopy. Embryonic development of black neon tetra concluded at 24 ± 0.5°C water temperature at 20-21 hours. The first embryonic division occurs within the first 43 minutes after fertilization, and the process goes on to blastula at 02 hours and 28 minutes. The gastrula stage began at 02.57 hours, while 6 somite segmentation stages were observed to occur at 08.14 hours. Following the pharyngula stage seen between 17 to 20 hours, the hatching occurred at 20-21hours. The results of this study can provide significant benefits to professional breeders in the aquaculture of black neon tetra and other ornamental fish species.