Resistance Of Shrimp Research Articles

INCREASED RESISTANCE OF PENAEUS MONODON TO WHISPOVIRUS CAUSES WHITE SPOT SYNDROME THROUGH ANTIVIRUS GENE TRANSFER

The shrimp species Penaeus monodon is the main commodity of Indonesian aquaculture. One of the obstacles when cultivating tiger prawns is the attack of white spot disease (White Spot Syndrome Virus) which makes the quality and quantity of production decrease. One attempteffective for overcoming the white spot virus attack on shrimp, namely through the transfer of antiviral genes. Previous researchers carried out the transfer of antiviral genes to provide immunological effects so that they were resistant to pathogen attack and could prevent the death of tiger prawns. Destinationwriting article that is This study aims to determine the increase in resistance of tiger shrimp to Whispovirus that causes White Spot Syndrome through the transfer of antiviral genes. The type of research conducted is descriptive qualitative with a literature review method that discusses five focus studies, namely Whispovirus as a cause of White Spot Syndrome Virus (WSSV) disease in tiger prawns, tiger shrimp infected with White Spot Syndrome Virus, the use of PmAV antiviral genes in the treatment of Whispovirus , the mechanism of transfection of antiviral genes in the treatment of Whispovirus infection against tiger prawns, and changes in tiger shrimp resistance after insertion of antiviral genes. The conclusion obtained is that the addition of antiviral genes in tiger shrimp DNA can increase its resistance to Whispovirus.

Probiotic, Lactobacillus pentosus BD6 boost the growth and health status of white shrimp, Litopenaeus vannamei via oral administration

This study aims to assess and determine the oral-administration of probiotic, Lactobacillus pentosus BD6 on growth performance, immunity and disease resistance of white shrimp, Litopenaeus vannamei. Lac. pentosus BD6 effectively inhibited the growth of aquatic pathogens, which was used in the test. Shrimp were fed with the control diet (without probiotic supplement) for 60 days and the probiotic-containing diets at 107, 108, 109, and 1010 cfu kg−1, respectively. Shrimp fed with the diet containing probiotic at the doses of 109−10 cfu kg−1 showed significant increase in growth performance as well as feed efficiency than that of the control. After a challenge test with Vibrio alginolyticus, shrimp fed with a probiotic diet at a dose of 1010 cfu kg−1 showed a significantly lower mortality as compared to the control and that of shrimp fed the diet containing probiotic at the levels up to 107−8 cfu kg−1. In addition, a therapeutic potential of Lac. pentosus BD6 was discovered because the cumulative mortalities of shrimp fed with probiotic and pathogen V. parahaemolyticus simultaneously were significantly lower when compared to control shrimp. Probiotic in diet at a dose of 109−10 cfu kg−1 significantly increased PO activity of shrimp, while shrimp receiving probiotic at the doses of 108−10 cfu kg−1 showed significant increase in lysozyme activity and phagocytic activity. Shrimp fed with the diet containing probiotic at the level of 1010 cfu kg−1 also indicated higher gene expression of prophenoloxidase (proPO) I, but not proPO II, lipopolysaccharide and β-1,3-glucan-binding protein and penaeidin 4. Analysis of the bacterial microbiota of the shrimp intestine revealed that oral administration of probiotic increased the relative abundance of beneficial bacteria and reduced the abundance of harmful pathogenic bacteria in the gut flora of shrimp. Despite no statistically significant difference, an analysis of microbial diversity recorded higher species richness, Shannon–Weaver diversity index and evenness in the probiotic group, compared to the control group. It was concluded that Lac. pentosus BD6 has great antibacterial ability against a wide range of pathogens and has therapeutic potential to reduce the mortality of shrimp infected with V. parahaemolyticus. Additionally, dietary Lac. pentosus BD6 at the level of 1010 cfu kg−1 was recommended to improve growth performance, immunity and disease resistance of shrimp against V. alginolyticus.

Metabolomic Profiles in the Intestine of Shrimp Infected by White Spot Syndrome Virus and Antiviral Function of the Metabolite Linoleic Acid in Shrimp

White spot syndrome virus (WSSV) is a threatening pathogenic virus in shrimp culture, and at present, no effective strategy can prevent and control the disease. Intestinal flora and its metabolites are important for the resistance of shrimp to lethal pathogenic viruses. However, the changes of metabolites in the shrimp intestines after WSSV infection remain unclear. We established an artificial oral infection method to infect shrimp with WSSV and analyzed the metabolites in intestinal content of shrimp by HPLC and tandem mass spectrometry. A total of 78 different metabolites and five different metabolic pathways were identified. Among them, we found that the content of linoleic acid, an unsaturated fatty acid, increased significantly after WSSV infection, indicating that linoleic acid might be involved in antiviral immunity in shrimp. Further study showed that, after oral administration of linoleic acid, WSSV proliferation decreased evidently in the shrimp, and survival rate of the shrimp increased significantly. Mechanical analysis showed that linoleic acid directly bound to WSSV virions and inhibited the viral replication. Linoleic acid also promoted the expression of antimicrobial peptides and IFN-like gene Vago5 by activating the ERK-NF-κB signaling pathway. Our results indicated that WSSV infection caused metabolomic transformation of intestinal microbiota and that the metabolite linoleic acid participated in the immune response against WSSV in shrimp.

Replacement of fish meal with Methanotroph (Methylococcus capsulatus, Bath) bacteria meal in the diets of Pacific white shrimp (Litopenaeus vannamei)

Methanotroph (Methylococcus capsulatus, Bath) bacteria meal is a kind of bacterial protein meal (BPM) with an excellent nutrition profile. This study evaluated the effects of replacing fish meal (FM) with BPM on growth, antioxidant capacity, intestinal morphology, and gut microbiota of Pacific white shrimp (Litopenaeus vannamei). A basal diet was formulated to contain 25% FM, then 15, 30 and 45% of FM was replaced with BPM, which were identified FM, BPM15, BPM30, and BPM45 diets, respectively. Triplicate groups (40 shrimp per replicate) of shrimp (0.88 ± 0.01 g) were fed the test diets to apparent satiation four times daily for 7 weeks. There were no significant differences in growth performance among four groups. Malondialdehyde content and anti-oxidative enzymes activity in hepatopancreas were significantly increased with increasing BPM levels. For intestinal histology, the circular muscle layer thickness was significantly increased in BPM45. The mucosal folds height of shrimp fed BPM45 was significantly higher than those fed BPM15. The width of mucosal folds in BPM15 and BPM30 was significantly reduced comparing with FM. Transmission electron microscopy results showed that intestinal microvilli was impaired and endoplasmic reticulum stress was present in shrimp fed BPM45 diet. However, dietary BPM improved the diversity of intestinal microbiota, and more beneficial microbiota such as Pseudoalteromonas, Ruegeria, and Lactobacillus, as well as less harmful microbiota such as Vibrio were found in the gut of BPM45. A 12-day challenge study with Vibrio parahaemolyticus showed that shrimp fed diet BPM15 had a significantly lower mortality throughout the challenge trial. To conclude, BPM replacement of fish meal did not affect growth performance and feed utilization of shrimp. The high dietary inclusion of BPM increased the oxidation level in the hepatopancreas of shrimp and BPM was able to increase the height of the mucosal folds, improve the gut microbiota structure and increase the disease resistance of shrimp.

A gelatinized lipopeptide diet effectively modulates immune response, disease resistance and gut microbiome in Penaeus vannamei challenged with Vibrio parahaemolyticus

Penaeus vannamei is one of the most economically vital shrimp globally, but infectious diseases have hampered its proper production and supply. As antibiotics pose a huge threat to the environment and humankind, it is essential to seek an alternative strategy to overcome infection and ensure proper culture and production. The present study investigates the effect of an anti-infective biosurfactant derivative lipopeptide MSA31 produced by a marine bacterium on the growth performance, disease resistance, and the gut microbiome of P. vannamei when challenged with pathogenic Vibrio parahaemolyticus SF14. The shrimp were fed with a commercial and lipopeptide formulated diet for 60 days and the growth performance was analyzed. The lipopeptide fed shrimp group showed enhanced growth performance and specific growth rate with improved weight gain than the control group. The challenge experiment showed that the survival rate was significant in the lipopeptide fed group compared to the control group. The results revealed 100% mortality in the control group at the end of 12 h of challenge, while 50% of the lipopeptide diet-fed group survived 24 h, which indicates the enhanced disease resistance in shrimp fed with a lipopeptide diet. The test group also showed higher levels of digestive and immune enzymes, which suggests that the lipopeptide diet could positively modulate the digestive and immune activity of the shrimp. The gut microbiome profiling by Illumina high-throughput sequencing revealed that the most abundant genera in the lipopeptide diet-fed group were Adhaeribacter, Acidothermus, Brevibacillus, Candidatus, Mycobacterium, Rodopila, and Streptomyces, while opportunistic pathogens such as Streptococcus, Escherichia, Klebsiella, Neisseria, Rhizobium, and Salmonella were abundant in the control diet-fed shrimp. Also, lipopeptide diet-fed shrimp were found to have a high abundance of ammonia and nitrogen oxidizing bacteria, which are essential pollutant degraders. Therefore, the study reveals that the dietary supplementation of lipopeptide in shrimp aquaculture could positively modulate the gut microbiome and enhance the shrimp's overall health and immunity in an eco-friendly manner.

Update on the use of yeast in shrimp aquaculture: a minireview

Growth in shrimp farming has shown an expansion of rearing farms and intensification of production methods, which have affected shrimp health, growth and survival and environmental integrity of the coastal areas, making the long-term viability of this farming industry doubtful. This industry demands alternative strategies to improve shrimp production, enhance disease resistance and take good care of the environment. Yeasts (live cell, total cell, or their active by-products) confer a benefit to the host by providing nutrition and protection against pathogens. This review summarizes the current knowledge of yeast species on: (i) shrimp aquaculture; (ii) shrimp nutrition; (iii) shrimp immunity; (iv) water and environment. Yeasts are used as alternative feed ingredients in aquaculture because of their nutritional value. Some products, such as b-glucans, chitin, nucleic acids, mannan oligosaccharides, b-carotene, B-complex, torulene, and torularhodin have been used in shrimp diets, showing direct effect on shrimp growth. Amylases, chitinases, phytases, and proteases are used to enhance gut maturity and digestive enzyme activity in shrimp larvae. The immune and antioxidant proprieties of yeasts have an important role as probiotics and immunostimulants to enhance shrimp resistance against common viral and bacterial diseases. Yeast bioactive products, such as glucans, nucleotides, polysaccharides, carotenoid pigments, lipids, proteins, and vitamins, activate the immune response directly or improve intestinal microbiota, specially glucans, which enhance shrimp circulating hemocytes (THC), phagocytosis, encapsulation, ProPO activity and melanization. Different yeast species, such as Debaryomyces sp., Candida sp., Rhodosporidium sp., Saccharomyces sp., and Yarrowia sp. have recently gained popularity as beneficial candidates in farmed organisms to maintain health conditions and well-being of different aquatic animals, including rearing shrimp. In addition, this study condensed current knowledge of the ability of yeasts to sustain the performance of marine shrimp and provide information for future research and development of yeast application in aquaculture.

Analysis of Vannamei shrimp DNA fragment resistant to White Spot Virus Syndrome

The attack of WSSV in Vannamei shrimp cultivation is still common. Shrimp quality improvement can be made through selection with the help of markers (marker-assisted choice). This study aimed to evaluate the DNA fragment profile of white shrimp that was resistant to WSSV disease. The analysis was performed using the PCR-RAPD method. WSSV challenged four groups of 100 Vannamei shrimp, then DNA was extracted from live and dead shrimp. The results showed that 2 of the 17 primers tested had high potential as markers, namely OP-09 and OPD-2. PCR products with OPC-09 primers had specific DNA bands measuring about 1.2 kb in all post-challenge WSSV resistant shrimp individuals. The amplification results using OPD-02 primers showed a particular band of DNA with a length of about 1.0 kb, with 60 % of the appearance in WSSV-resistant shrimp. In contrast, the WSSV-susceptible shrimp group did not have specific DNA fragments. Thus, the two RAPD primers had a high chance of being used in the selection with the help of markers to produce WSSV resistant shrimp.

Effects of the Monomeric Components of Poly-hydroxybutyrate-co-hydroxyhexanoate on the Growth of Vibrio penaeicida In Vitro and on the Survival of Infected Kuruma Shrimp (Marsupenaeus japonicus).

Simple SummaryOutbreaks of bacterial disease in shrimp aquaculture are major causes of economic and production losses. It is, therefore, important to prevent such outbreaks, preferably without the use of antibiotics to avoid encouraging the development of antibiotic-resistant bacterial strains. Several hydroxyalkanoic acids are known to inhibit the growth of pathogenic Vibrio species. Poly-hydroxybutyrate-co-hydroxyhexanoate is a biodegradable, water-insoluble polymer comprising two hydroxyalkanoic acids: 3-hydroxybutyrate and 3-hydroxyhexanoate. Here, we evaluated the inhibitory activities of 3-hydroxybutyrate and 3-hydroxyhexanoate on the growth of the shrimp-pathogenic bacterium Vibrio penaeicida in vitro, and the effect of adding poly-hydroxybutyrate-co-hydroxyhexanoate to the diet on the survival of infected kuruma shrimp (Marsupenaeus japonicus). We found that the activities of 3-hydroxybutyrate and 3-hydroxyhexanoate were pH dependent and that they inhibited bacterial growth at pH close to that found in the shrimp gut (pH 5.9–6.7). Moreover, in shrimp infected with V. penaeicida, survival rates were significantly increased in individuals reared on feed containing poly-hydroxybutyrate-co-hydroxyhexanoate compared with those reared on standard diet, without any negative effects on shrimp growth. These findings suggest that supplementation of standard diet with poly-hydroxybutyrate-co-hydroxyhexanoate could protect aquaculture shrimp from infection by V. penaeicida, which is expected to increase production and reduce overall operational costs.Here, we investigated the inhibitory effects of the biodegradable, water-insoluble polymer poly-hydroxybutyrate-co-hydroxyhexanoate (PHBH) and its two constituent monomers, the hydroxyalkanoic acids 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HH), on the growth of the shrimp-pathogenic bacterium Vibrio penaeicida. In vitro experiments revealed that 3HH showed greater growth inhibitory activity than 3HB against V. penaeicida. In addition, the activities of hydroxyalkanoic acids were pH dependent, being greater at pH 6.0 than at pH 7.0. Investigation of the pH of the shrimp gut revealed a pH range of 5.9–6.7 (mean 6.29 ± SD 0.20), indicating that the physiological environment was suitable for 3HB and 3HH to exert their inhibitory activities against V. penaeicida. In vivo bacterial challenge experiments revealed that survival rates in kuruma shrimp (Marsupenaeus japonicus) infected by V. penaeicida were significantly increased in shrimp reared on feed containing PHBH (0.1%–5% w/w PHBH) compared with that in shrimp reared on standard diet alone. Supplementation with PHBH had no significant effects on three shrimp growth parameters: increase in body weight, daily feeding rate, and feed conversion ratio. These results suggest that supplementation of standard diet with PHBH will increase shrimp resistance to infection by V. penaeicida, thereby increasing shrimp aquaculture productivity.

English

White spot syndrome virus (WSSV) is a significant cause of tiger shrimp mortality, and has a profound economic impact on commercial shrimp farming. A transgenic technology provides an effective method to control the viral disease by increasing the shrimp resistance. The study aimed to assess the overexpression of the PmAV (Penaeus monodon antiviral) gene on the embryo/larvae of tiger shrimp and the performance of transgenic shrimp by WSSV-challenge test. Transfection of pProAV-PmAV gene construct into the embryo was conducted using jetPEI reagent. Transient antiviral gene expression was detected at 12, 18, 24 and 30 h post transfection (hpt). The tiger shrimp larvae of PL-25 were challenged by waterborne infection technique. Survival and expression of antiviral genes were observed after challenge test. The results showed that the PmAV gene and the jetPEI reagent did not have the toxicity to the tiger shrimp larvae. The transient antiviral gene expression was exhibited at 12 hpt until the peak reached within 24 hpt and then decreased slightly at 30 hpt. This suggested that the expression of PmAV during infection was an up-regulated sign. The challenge test result showed that the transgenic tiger shrimp exhibited higher resistance (P < 0.05) to the WSSV infection (95.6% survival rate) than the control shrimp (71.1% survival rate). The 47-day transgenic tiger shrimp did not show significant difference (P > 0.05) in body weight and length gain as well as appearance, morphology, and activity from normal control shrimps. © 2021 Friends Science Publishers

Effects of dietary hydrolyzable tannins on growth performance, antioxidant capacity, intestinal microflora and resistance against Vibrio parahaemolyticus of juvenile Pacific white shrimp, Litopenaeus vannamei (Boone, 1931)

Tannins have great potential as an alternative to in-feed antibiotics. However, no study has investigated the effects of tannins on shrimp. The present study assessed the eff ;ects of hydrolyzable tannins (HTs) fed at different inclusion levels (F0: control, F0.5: 0.05 %, F1: 0.1 %, F1.5: 0.15 % and F2: 0.2 % (g−1 feed) on the growth performance, antioxidant capacity, immune response, intestinal microflora and resistance to Vibrio parahaemolyticus of juvenile Pacific white shrimp (Litopenaeus vannamei). After 60 days of the feeding trial, a significant increase (P < 0.05) of weight gain rate (WGR), specific growth rate (SGR), activities of alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD) and trypsin in serum and hepatopancreas, and the expression level of catalase (CAT), Cu/Zn superoxide dismutase (Cu/Zn-SOD) and glutathione peroxidase (GPx) gene in the hepatopancreas of 0.15 % HT treated groups were achieved. The dietary supplementation of HTs also changed the composition of intestinal microflora. At the phylum level, Proteobacteria accounted for the majority of bacteria, followed by Firmicutes, Bacteroidetes and Actinobacteria. At the genus level, Stenotrophomonas, Ruegeria, and Photobacterium were dominant in the F0.5, F1, and F1.5 groups, respectively. The relative abundance of Vibrio and Carboxylicivirga decreased in the intestines of shrimp fed with HTs diets. Furthermore, F1.5 group showed the highest relative percent survival value (80 %) (P < 0.05), which indicates that the supplementation of 0.15 % HTs in challenge test significantly enhanced the resistance of shrimp against V. parahaemolyticus infection after 24 h. These results indicated that 0.15 % HTs could remarkably improve the growth performance, antioxidant capacity, intestinal microflora, and resistance against V. parahaemolyticus of L. vannamei, and can be a potential feed additive for shrimp in aquaculture. According to our study, the optimal dietary supplementation dosage of HTs is 0.15 % feed in diets.

Effects of dietary supplementation of monobutyrin and tributyrin on growth, feed efficiency, innate immunity, digestibility and disease resistance of Pacific white shrimp ( Litopenaeus vannamei ) against Vibrio harveyi

This study was conducted to evaluate the supplemental effects of esterified monobutyrin (MB) and tributyrin (TB) on growth performance, feed efficiency, digestibility, innate immunity, antioxidant status and disease resistance of Pacific white shrimp, Litopenaeus vannamei. A basal (control) experimental diet was formulated without MB or TB, and four other diets were prepared by supplementing powder forms of MB at 2 and 4 g/kg (0.2% and 0.4%) or TB at 1 and 2 g/kg (0.1% and 0.2%) (designated as MB0.2, MB0.4, TB0.1 and TB0.2, respectively). Quadruplicate groups of shrimps were hand-fed with one of the diets four times daily for 53 days. Shrimp fed MB or TB diets showed significantly higher growth performance, feed utilization, phagocytosis and glutathione peroxidase activity than shrimp fed the control diet. Increased digestibility of dietary protein, lipid and dry matter was found in shrimp fed MB- or TB-supplemented diets. Relative mRNA expression levels of IGF-binding protein and prophenoloxidase gene were significantly increased in shrimp fed MB- or TB-supplemented diets than in shrimp fed the control diet. The results of a challenge test with Vibrio harveyi showed that the disease resistance of shrimp can be significantly enhanced against V. harveyi when they were fed TB0.2 diet. The results of this study indicate that dietary supplementation of 2 g/kg MB or 1–2 g/kg TB can improve growth and feed efficiency, innate immunity, antioxidant activity, digestibility and disease resistance of L. vannamei.

Research Article: Dietary administration of aqueous Zingiber officinale extract on growth performance, antioxidant activity and resistance of shrimp Litopenaeus vannamei against Photobacterium damselae

This study was conducted to evaluate the effect of Zingiber officinale extract (ZE) on growth performance, antioxidant activity and resistance of shrimp (Litopenaeus vannamei) challenged with Photobacterium damselae bacteria. A total of 600 post larvae shrimps (initial weight, 1.06 ± 0.7 g) were randomly distributed into 12 fiberglass tanks representing four treatments at a rate of 50 shrimp in each tank. The control shrimp group (ZE0) was fed a ZE free basal diet. Other shrimp groups were fed the basal diet supplemented with 0.5 (ZE 0.5), 1.0 (ZE1) and 1.5 (ZE 1.5) g kg-1 diet. Diets were offered to shrimp at a feeding rate of 10% of live body weight for 8 weeks. After 8 week experimental trial 30 shrimp from each group was infected with LD70 bacteria P. damselae over 10 days to evaluated disease resistance of infected shrimp. Results revealed that growth performance (WG, SGR, FW and PER), the antioxidant activity (SOD, PO, GPx, CAT) and cumulative mortality percentage of the shrimp have significantly increased (p <0.05) in the ZE1 group compared with the other groups. Meanwhile, the lowest FCR and MDA value observed in shrimp fed ZE1 supplemented diet. It can be concluded that Z. officinale extract at 1g kg-1(ZE1) diet seems to be the most appropriate level for increasing growth performance antioxidant activity and disease resistance of L. vannamei

Effect of Brachionus plicatilis and Navicula sp. on Pacific white shrimp growth performance, Vibrio, immunological responses and resistance to white spot virus (WSSV) in nursery biofloc system

The purpose of this study was to evaluate the effect of Brachionus plicatilis and Navicula sp. addition on growth performance, Vibrio count, immunological responses and resistance to white spot syndrome virus (WSSV) of Litopenaeus vannamei in nursery biofloc system. The study was divided into two phases and four treatments were examined in the first phase: BFT (biofloc); BFT-N (addition of 10×104 cells mL−1 of Navicula sp.); BFT-B (addition of 30 org mL−1 of B. plicatilis) and; BFT-BN (addition of 10×104 cells mL−1 of Navicula sp. and 30 org mL−1 of B. plicatilis), all in triplicate and; the second phase included a viral challenge, also in triplicate. Shrimp (PL10, 2 ± 0,01 mg) were reared in biofloc system (fertilized with inorganic and anaerobic and aerobic carbon process with a microbial mix), for 45 days at a density of 3000 shrimp m-3, with controlled temperature, without water exchange and fed with commercial feed. The diatoms and rotifers were added every 10 days, and at the end, shrimp performance, water quality, Vibrio count and total hemocyte count were evaluated. After 45 days, 300 shrimp m−3 were challenged with WSSV (2.2 × 107 copies of WSSV μL−1 of DNA) for 9 days. The BFT-N, BFT-B and BFT-BN treatments had higher values of final weight (1.02 to 1.16 g) and yield (2.85 to 3.30 kg m−3) which were higher than the BFT (0.86 g and 2.46 kg m−3). There were no differences in water quality among treatments. Vibrio count from water samples was significantly lower at the end of experiment with significant decrease of non-sucrose-fermenting gram-negative bacteria. However, for hepatopancreas, the Vibrio count was significant higher at the end, however with significantly increase of sucrose-fermenting gram-negative bacteria (98 to 100%). There was no significant difference between the THC and hyalyne count for all treatments. Massive mortality rate was firstly achieved in BFT and BFT-B treatments in the second phase. However, all treatments reported complete mortality and WSSV infection was confirmed by nested-PCR and histopathologically, with lesions suggestive of WSD (presence of nodules and tissue deformations). The Navicula sp. and B. plicatilis addition contributed to better performance parameters of shrimp in the nursery biofloc system, although there was no significant effect on the WSSV resistance of shrimp. Absence of tissue degeneration in WSSV infected shrimp from BFT-N treatment indicated benefit of using diatoms under standardized conditions.

Genomic selection for white spot syndrome virus resistance in whiteleg shrimp boosts survival under an experimental challenge test

White spot syndrome virus (WSSV) causes major worldwide losses in shrimp aquaculture. The development of resistant shrimp populations is an attractive option for management of the disease. However, heritability for WSSV resistance is generally low and genetic improvement by conventional selection has been slow. This study was designed to determine the power and accuracy of genomic selection to improve WSSV resistance in Litopenaeus vannamei. Shrimp were experimentally challenged with WSSV and resistance was evaluated as dead or alive (DOA) 23 days after infestation. All shrimp in the challenge test were genotyped for 18,643 single nucleotide polymorphisms. Breeding candidates (G0) were ranked on genomic breeding values for WSSV resistance. Two G1 populations were produced, one from G0 breeders with high and the other with low estimated breeding values. A third population was produced from “random” mating of parent stock. The average survival was 25% in the low, 38% in the random and 51% in the high-genomic breeding value groups. Genomic heritability for DOA (0.41 in G1) was high for this type of trait. The realised genetic gain and high heritability clearly demonstrates large potential for further genetic improvement of WSSV resistance in the evaluated L. vannamei population using genomic selection.

Involvement of oxygenase confers higher resistance to neonicotinoid insecticides in estuarine resident sand shrimp Crangon uritai than in kuruma prawn Penaeus japonicus and mysid Americamysis bahia

Globally, neonicotinoid contamination in aquatic environments, including estuarine areas, is a prevailing environmental concern. The estuarine resident marine crustacean sand shrimp Crangon uritai was previously found to have a higher tolerance to neonicotinoids than the marine crustaceans kuruma prawn Penaeus japonicus and mysid Americamysis bahia. Based on these findings, we aimed to explore the mechanisms underlying their differences in insecticide sensitivity. We hypothesized that differences in the structures of their nicotinic acetylcholine receptors (nAChRs) and/or the involvement of a metabolizing enzyme may confer sand shrimp resistance to neonicotinoids. No obvious differences were found in the amino acid residue (position 81) of the loop D region of the nAChR β-subunit among the three crustaceans. A synergistic toxicity bioassay was used to explore candidate metabolizing enzymes, esterase, glutathione S-transferase, and oxygenase. The three species were exposed to two neonicotinoids (acetamiprid and clothianidin) at concentrations equivalent to 1/15–1/10 of 96-h LC50 values and synergists (inhibitors of metabolizing enzyme) or combinations of both. Treatments with the oxygenase inhibitor and the neonicotinoids resulted in increased mortality in sand shrimps but not in kuruma prawns or mysids. Consequently, it was determined that oxygenase may explain the higher resistance of the sand shrimp to neonicotinoid insecticides.

Exploration of bacteria associated with Nudibranchs to control Vibrio spp.

Shrimp culture process of Litopenaeus vannamei could not be separated from the disease threats. Vibriosis is the main cause of a decrease in aquaculture production. Vibrio harveyi is a pathogenic bacteria that can caused high mortality and Vibro parahaemolyticus can also cause massive financial losses in shrimp culture. The use of antibiotics to control vibriosis, however, has a negative impact. For example, it resulted in the shrimp resistance to pathogenic bacteria. The potential of bacteria that are symbiotic with nudibranchs as anti Vibrio spp. has not been reported yet. The aim of this experiment was to examine the presence of bacterial symbiont in a nudibranch to inhibit or stop the growth of V. harveyi. Antibacterial activity test was done by the overlay method. The tested pathogenic bacteria were used V. harveyi and V. parahaemolyticus. Then the active bacteria were identified by morphological and molecular using 16S rRNA gene sequence. Isolation of bacterial symbiont in Nudibranch revealed 144 isolates. From those isolates only one isolate (SM-N-3(2)/7) was identified as having the ability against V.harveyi and V. parahaemolyticus. The isolate was gram negative rod bacteria. Based in molecular identification using 16S rRNA it was closely related to Pseudoalteromonas piscicida strain NBRC (99%).

Estimating genetic parameters for resistance to Vibrio parahaemolyticus with molecular markers in Pacific white shrimp

Acute hepatopancreatic necrosis disease (AHPND), whose causative agent was Vibrio parahaemolyticus (VPAHPND), has caused large economic loss in shrimp industry. To reduce the loss caused by AHPND, selective breeding aiming to improving the resistance of shrimp to VPAHPND is a significant approach. However, to avoid common environmental effects and deal with situation of no ideal pedigree, developing genetic evaluation method based on molecular markers was necessary. The object of this study was to estimate the genetic parameters of the resistance to VPAHPND in Pacific white shrimp, and to compare the estimation accuracies of shrimp breeding values on the resistance to VPAHPND based on molecular relatedness (MR) and pedigree relatedness (PR) from pedigree reconstruction by cross validation. Twelve microsatellites were applied in 678 offspring (full data set), of which 351 offspring (reduced data set) were assigned to 50 female parents successfully. Heritability of the survival time (ST) and the survival status at the half-lethal time (SS50) were 0.23 ± 0.10 and 0.12 ± 0.08 using PR in reduced data set. When MR was used, they were 0.15 ± 0.07 and 0.10 ± 0.06 estimated by the reduced data set, 0.20 ± 0.05 and 0.11 ± 0.04 estimated by the full data set. Cross-validation of both methods using the reduced data set showed an accuracy of estimated breeding values of 0.584 with PR and 0.608 with MR. Accuracy of estimated breeding values increased to 0.657 when applying MR to the full data set. Our results indicate that genetic improvement of shrimp is feasible and MR is an alternative to pedigree reconstruction in genetic evaluation for this trait.

Fortification of chitosan and mangrove flour as windu shrimp feed (Penaeusmonodon) against infection white spot syndrome virus

Langsa is one of the largest Windu shrimp producing areas in ACEH that holds considerable potential in the cultivation of windu shrimp. But recently the production of tiger shrimp has deteriorated due to by various disease attacks that have caused shrimp deaths including White Spot Syndrome Virus. This disease is a crop failure disease with high levels of mordibity and mortality. Transmission of WSSV was very fast and led to a 100% death within 3-10 days since the clinical symptoms arose. Therefore, research is conducted to prevent and treat WSSV by using shrimp skin and mangrove flour as feed. Chitosan flour from shrimp skin waste has the potential to be used as feed. The aim of this study was to determine the effect of fortification of chitosan and mangrove flour as windu shrimp feed on physiological conditions of windu shrimp. Physiological observations carried out include feeding responses, swimming, body redness (body color changes), white spots on the carapace and counting shrimp that die during maintenance. Physiological observations carried out include feeding responses, swimming, body redness (body color changes), white spots on the carapace and counting shrimp that die during maintenance. Based on the results of the study show that the more mangrove flour and chitosan fortified in shrimp feed, the level of shrimp resistance to white spot syndrome virus infection is increasing which is characterized by a low mortality rate.

A Polymorphic (CT)n-SSR Influences the Activity of the Litopenaeus vannamei IRF Gene Implicated in Viral Resistance.

Simple sequence repeats (SSRs) of short nucleotide motifs occur very frequently in the 5′ untranslated coding region (5′-UTR) of genes and have been implicated in the regulation of gene expression. In this study, we identified an SSR with a variable number of CT repeats in the 5′-UTR of the Litopenaeus vannamei IRF (LvIRF) gene that has been shown to mediate antiviral responses by inducing the expression of Vago, a functional homolog of mammalian IFN. We then explored the effects of varying the number of (CT)n repeats on the expression of LvIRF using both dual-luciferase reporter assays and Western blots. Our results demonstrate that the length of the (CT)n-SSR in this gene can influence the expressional level of LvIRF, in that a shorter (CT)n repeat had a stronger ability to induce the expression of LvIRF. Moreover, we found that the (CT)n repeat in LvIRF was associated with viral resistance in shrimp. Individual shrimps with shorter (CT)n repeats in the 5′-UTR of LvIRF exhibited high tolerance to white spot syndrome virus (WSSV), and this trait was inherited in offspring. Taken together, these results indicated that this (CT)n-SSR could be used as a molecular marker for shrimp breeding for WSSV resistance.

Multienzymatic capacity of cultivable intestinal bacteria from captive Litopenaeus vannamei (Boone, 1931) shrimp reared in green water

Equilibrium between the gastrointestinal bacterial population and the environment is a critical factor for the health of captive aquatic animals. The bacterial enzymes are fundamental for proper nutrition and pathogen resistance in shrimp. Therefore, enzymatic profiles reveal essential characteristics for the selection of probiotic strains that can improve animal development. In this work, we analysed shrimp from a green water system where infectious myonecrosis virus (IMNV) was present. We isolated transient and intestine resident bacterial populations, characterising eight functional groups through different culture media. To identify each isolated bacteria, we used sequences from regions V6–V8 of the 16S rRNA. To determine viral load of shrimp samples, we used real-time PCR. The number of colony forming units (CFU) was similar between IMNV-infected and IMNV-uninfected shrimps. The growth of transient bacteria was higher than the growth of resident. In general, lipolytic bacteria presented higher frequency and genus diversity than the other functional groups. All groups showed higher frequency among transitory bacteria, except the amylolytic functional group, which was more frequent among the resident. We found two major orders of cultivable bacteria, Vibrionales and Bacillales. The genus Vibrio was predominant among the Vibrionales, while Staphylococcus and Bacillus were the most frequent among the Bacillales. Recorded Vibrionales and Bacillales included pathogenic and beneficial species of high importance for aquaculture. The results presented here will serve as a basis for improving the nutritional and health conditions of Litopenaeus vannamei in green water farming systems.