Pacific Whiteleg Shrimp Litopenaeus Vannamei Research Articles

Shrimp industry in China: overview of the trends in the production, imports and exports during the last two decades, challenges, and outlook

China’s shrimp farming industry has experienced significant growth in recent years. With such a development, some major constraints linked to the industry’s sustainable development have emerged. This paper aims to present an overview of China’s shrimp industry over the last two decades, with special attention to farm-raised shrimp both in marine and inland waters. Documentary research on its recent evolution was carried out based on data collected from China Fishery Statistics Yearbooks 2003 to 2022 coupled with data from FAO. Findings indicated that there has been an upward trend in China’s total shrimp production over the last 20 years, with a growth rate of 120%, representing an average annual growth rate of 4.3%. The observed higher shrimp production was driven by expanded shrimp aquaculture production, with major species dominated by the Pacific whiteleg shrimp (litopenaeus vannamei), the black tiger shrimp (Penaeus monodon), the Chinese shrimp (Penaeus chinensis), and the Japanese prawn (Penaeus japonicus). Challenges associated with the intensification of the production and the driven environmental deterioration need to be properly addressed. First, the shrimp farming industry should be practiced while considering both environment and ecosystem protection. Applying such an organic farming principle presupposes some practices for addressing the existing issues threatening the sustainable growth of the industry. To that end, there is a need for innovative techniques that should be strengthened. Second, possible solutions to shrimp disease problems, namely prevention, early diagnosis, and various control techniques, should also be developed and improved, with an emphasis on the former. In addition, encouraging the use of good-quality feed in appropriate quantity and form is also of paramount importance. It is thus worth noting that further policies need to focus on promoting a large range of ecological shrimp aquaculture technologies that should be encouraged among farmers.

Impacts of Dietary Selenium Nanoparticles from Spirulina platensis on Growth Performance, Physio-Biochemical Components and Alleviating Effect against Cadmium Toxicity in Pacific White Shrimp Litopenaeus vannamei

Shrimp culture is quite important and popular across the world. This study aimed to evaluate the growth-promoting potential of synthesized selenium nanoparticles from Spirulina platensis extract (SP-SeNPs) as a food source for Pacific whiteleg shrimp (Litopenaeus vannamei). However, pollution is considered a significant element affecting shrimp health and development. The effectiveness of SP-SeNPs in alleviating the negative effects of cadmium toxicity was also evaluated. Firstly, the shrimps (about 120 individuals with 6.0 ± 0.12 g of initial weight) were divided randomly into four groups in triplicates (30 shrimps/ treatment). The control group (SP-SeNPs—0 mg/kg diet) and three treatments were fed dietary SP-SeNPs (0.250, 0.50, and 1.0 mg/kg diet) for 56 days. Growth performance, digestive enzymes activities (protease, amylase, and lipase), and other biochemical components (total protein, lipid, amino acids, and carbohydrate) were evaluated. After 56 days of growth, another 150 adult shrimps were used under laboratory conditions to determine median lethal concentration of cadmium (96 h LC50), and 30 individuals were treated with cadmium (1/2 of LC50, 0.2 mg L−1) for 10 days only. Tissue samples were collected for measuring catalase (CAT), total antioxidant capacity (TAC), superoxide dismutase (SOD), malondialdehyde (MDA) levels, cadmium bioaccumulation, and histopathological investigation. The results illustrated that the application of SP-SeNPs as feed additives at varying levels significantly improved growth performance (high weight gain, specific growth rate, and low feed conversion rates) relative to the control group. Furthermore, dietary SP-SeNPs enhanced digestive enzyme activities and the concentrations of biochemical components more than the control group. Upon concurrent exposure to cadmium, the antioxidative status was significantly enhanced, and histopathological alterations were mitigated. In conclusion, this study recommended supplementation of SP-SeNPs at 0.50 mg/kg diet to enhance optimal growth rate, digestive enzyme activities, levels of antioxidants in Litopenaeus vannamei, and mitigate the pathological alternations induced with Cd toxicity.

Polystyrene nanoplastics induce lipid metabolism disorder and alter fatty acid composition in the hepatopancreas of Pacific whiteleg shrimp (Litopenaeus vannamei)

The impact of nanoplastics (NPs) on environmental pollution and aquatic organisms has gradually attracted attention, but there are relatively few reports of the effects of NPs on the lipid metabolism of crustaceans. In this study, we exposed Pacific whiteleg shrimp (Litopenaeus vannamei) to different concentrations of polystyrene NPs (0, 0.1, 1, 5, and 10 mg/L) for 28 days. We then evaluated the effects of NP exposure on metabolite content, histology, lipid metabolism-related enzyme activity, and gene expression. Our results showed that with increasing NPs concentrations and exposure time, (1) the crude protein and crude fat content decreased and fatty acid composition changed; (2) the tissue structure was destroyed and the number of lipid droplets increased in the hepatopancreas; (3) the activities of acetyl-CoA carboxylase, fatty acid synthase, carnitine palmitoyl transferase-1, pyruvate kinase and low-density lipoprotein content tended to decrease and that of lipase and high-density lipoprotein content first increased and then decreased; the content of triglycerides and total carbohydrate first decreased and then increased; (4) the expression of fatty acid synthesis-related genes (Fas, SREBP, and FAD), fatty acid transport-related genes (FATP, FABP, and ACBP), and fatty acid decomposition-related genes (Ampk and lip1) first increased and then decreased. These results indicate that exposure to NPs can cause physiological disorders of fat metabolism in L.vannamei and that high concentrations of NPs have a negative impact on lipid metabolism. These results of this study provide valuable ecotoxicological data for better interpretation of the mechanism of action of NPs in crustaceans.

Bioaccumulation of Metals in Pacific White-Leg Shrimp (Litopenaeus vannamei) and Sediment in Shrimp Farms of Gwatr Bay, Iran: Effects of Culture Cycle and Diet

Bioaccumulation of Metals in Pacific White-Leg Shrimp (Litopenaeus vannamei) and Sediment in Shrimp Farms of Gwatr Bay, Iran: Effects of Culture Cycle and Diet

Dynamic N6-methyladenosine RNA methylation landscapes reveal epi-transcriptomic modulation induced by ammonia nitrogen exposure in the Pacific whiteleg shrimp Litopenaeus vannamei

Despite the versatility of RNA m6A methylation in regulating various biological processes, its involvement in the physiological response to ammonia nitrogen toxicity in decapod crustaceans like shrimp remains enigmatic. Here, we provided the first characterization of dynamic RNA m6A methylation landscapes induced by toxic ammonia exposure in the Pacific whiteleg shrimp Litopenaeus vannamei. The global m6A methylation level showed significant decrease following ammonia exposure, and most of the m6A methyltransferases and m6A binding proteins were significantly repressed. Distinct from many well-studied model organisms, m6A methylated peaks in the transcriptome of L. vannamei were enriched not only near the termination codon and in the 3′ untranslated region (UTR), but also around the start codon and in the 5′ UTR. Upon ammonia exposure, 11,430 m6A peaks corresponding to 6113 genes were hypo-methylated, and 5660 m6A peaks from 3912 genes were hyper-methylated. The differentially methylated genes showing significant changes in expression were over-represented by genes associated with metabolism, cellular immune defense and apoptotic signaling pathways. Notably, the m6A-modified ammonia-responsive genes encompassed a subset of genes related to glutamine synthesis, purine conversion and urea production, implying that m6A methylation may modulate shrimp ammonia stress responses partly through these ammonia metabolic processes.

Phenotypic Differences in Pacific Whiteleg Shrimp (Litopenaeus vannamei, Boone 1931) Reared in Different Types of Culture Ponds-Statical Approach

Phenotypic Differences in Pacific Whiteleg Shrimp (Litopenaeus vannamei, Boone 1931) Reared in Different Types of Culture Ponds-Statical Approach

Study on the Microflora Structure in a Litopenaeus vannamei–Sinonovacula constricta Tandem-Culture Model Based on High-Throughput Sequencing under Different Culture Densities

In this study, we evaluated the intestinal contents of Pacific whiteleg shrimp (Litopenaeus vannamei), the visceral mass of razor clams (Sinonovacula constricta) and the water columns and the substrate sediments in different culture-density groups in a L. vannamei–S. constricta tandem-culture model by high-throughput sequencing of the 16S rRNA gene. The results show that the culture density affected the bacterial floral structure of the water columns, substrate sediment and razor-clam gut masses without making significant differences in the bacterial flora structure of the shrimp gut; the Shannon diversity indexes of the bacterial communities in the substrate sediment, shrimp gut and razor-clam gut masses were not significantly different among the density groups, and the Shannon diversity index of the bacterial communities in the water column was higher in the group with higher culture densities; at the phylum level, the dominant bacteria common to the shrimp guts, razor-clam visceral mass, water columns and substrate sediment were Proteobacteria and Bacteroidetes; Chloroflexi was the dominant bacterium specific to the substrate sediment; and Firmicutes was the dominant bacterium specific to the shrimp gut and razor-clam gut mass. We used national standards (GB 17378.4-2007, China) to evaluate the content of water-quality factors through the environmental factors and the genus-level correlation analysis of bacterial flora that follow: the dominant bacterium in the water column, uncultured_bacterium_f_Rhodobacteraceae, was negatively correlated with PO43−-P; the dominant bacteria in the substrate sediments, uncultured_bacterium_f_Anaerolineaceae and Woeseia, were significantly and negatively correlated with DO; and the dominant bacteria Lactococcus spp. in the razor-clam gut mass and the shrimp intestines were positively correlated with DO. These results show that culture density directly affects water-quality factors, which in turn affect the culture environment and the composition structure of the bacterial flora in a cultured organism.

Impacts of ammonia stress on different Pacific whiteleg shrimp Litopenaeus vannamei families and the underlying adaptive mechanisms

Ammonia stress in aquaculture systems poses a great threat to the growth and survival of the Pacific whiteleg shrimp Litopenaeus vannamei. Although the ammonia stress tolerance capacity of L. vannamei has been found to vary significantly among different breeding families, the underneath mechanisms are still largely unknown. In this study, the ammonia tolerance capacity of different L. vannamei breeding families was compared. Results confirmed the significant differences in the ammonia adaptability among different families. To ascertain the underlying adaptive strategies, ATP status, ATP synthase activity, expression and activities of ammonia excretion and metabolism-related enzymes, and apoptosis in shrimp gills were analyzed. Furthermore, transcriptomic analyses were also performed to elucidate the molecular mechanisms. Our results indicated that ammonia-tolerant L. vannamei may possess (1) enhanced ability to excrete ammonia, (2) better capacity to convert ammonia into less toxic products, and (3) sufficient energy reserves for ammonia-compensating processes.

LvCD14L Acts as a Novel Pattern Recognition Receptor and a Regulator of the Toll Signaling Pathway in Shrimp.

Leucine-rich repeat (LRR) is a structural motif has important recognition function in immune receptors, such as Tolls and NOD-like receptors (NLRs). The immune-related LRR proteins can be divided into two categories, LRR-containing proteins and LRR-only proteins. The latter contain LRR motifs while they are without other functional domains. However, the functional mechanisms of the LRR-only proteins were still unclear in invertebrates. Here, we identified a gene encoding a secretory LRR-only protein, which possessed similarity with vertebrate CD14 and was designated as LvCD14L, from the Pacific whiteleg shrimp Litopenaeus vannamei. Its transcripts in shrimp hemocytes were apparently responsive to the infection of Vibrio parahaemolyticus. Knockdown of LvCD14L with dsRNA resulted in significant increase of the viable bacteria in the hepatopancreas of shrimp upon V. parahaemolyticus infection. Further functional studies revealed that LvCD14L could bind to microorganisms' PAMPs, showed interaction with LvToll1 and LvToll2, and regulated the expression of LvDorsal and LvALF2 in hemocytes. These results suggest that LvCD14L functions as a pattern recognition receptor and activates the NF-κB pathway through interaction with LvTolls. The present study reveals a shrimp LvCD14L-Tolls-NF-κB signaling pathway like the CD14/TLR4/NF-κB signaling pathway in mammalians, which enriches the functional mechanism of secretory LRR-only immune receptors during pathogens infection in invertebrates.

Integrated microRNA-mRNA analysis reveals a possible molecular mechanism of enteritis susceptibility in Litopenaeus vannamei

Enteritis is one of the main diseases affecting Pacific whiteleg shrimp (Litopenaeus vannamei) in recent years, and it has resulted in huge losses to the aquaculture industry. Prior to this study, the molecular mechanism underlying enteritis in L. vannamei was unclear, and comprehensive multi-omics analysis had not been conducted. In this study, 1209 differentially expressed genes (DEGs) were identified from the hepatopancreas of L. vannamei with and without enteritis. Kyoto Encyclopedia of Genes and Genomes analysis showed that genes were significantly enriched in immune, metabolic, and endocrine regulatory pathways. Forty-eight significantly different microRNAs (miRNAs) were identified in the miRNA-Seq analysis. Further functional annotation analysis showed that the regulatory pathway of target gene enrichment of differentially expressed miRNAs was consistent with DEGs. Through miRNA-mRNA integration analysis, 47 meaningful miRNA-mRNA pairs were obtained, of which melanogenesis and pancreatic secretion were considered key pathways. Subsequent miRNA-mRNA interaction network analysis revealed that mja-miR-6493-3p, Mja-miR-6494, novel-198, novel-272, novel-261, novel-200, novel-183, novel-184, novel-237, and novel-192 may be key miRNAs involved in the regulation of these two signaling pathways. Finally, the RAS signaling pathway was found to inhibit the translation level of proteins in the hepatopancreas. These results suggest that target gene integration analysis of mRNA-miRNA can reveal the molecular mechanism underlying enteritis in L. vannamei and also provide valuable new insights for resisting enteritis.

A first glimpse into the m6A modification machinery of shrimp: Genomic features, expression patterns and potential roles in molting regulation

N6-methyladenosine (m6A) is the most abundant type of RNA modification in eukaryotes, yet information on the m6A methylation enzymatic machinery of decapod crustaceans is quite scarce. Here, three essential genes for m6A modification, including two m6A methyltransferases (LvMETTL3 and LvWTAP) and a m6A-binding protein (LvYTHDF2), were identified from the Pacific whiteleg shrimp Litopenaeus vannamei. Their genomic structures were dissected in an evolutionary context. Common transcription factor binding sites and conserved functional motifs were identified, but the three m6A modification genes also possessed some unique features, illustrating lineage-specific diversification of regulatory elements and functions of these genes. The three genes displayed ubiquitous tissue expression profiles, and showed dynamic expression changes at different molting stages. Following suppression of LvMETTL3, LvWTAP or LvYTHDF2 by RNA interference, the molting rate of shrimp was significantly accelerated, and expression of the molt inhibiting hormone MIH plummeted, while major genes in the ecdysone signaling pathway including EcR, RXR and E75 all showed significant induction. The results indicated that m6A modification may regulate shrimp molting process via MIH and the ecdysone signaling pathway. The current study provided the first molecular characterization of several key components of the m6A enzymatic machinery in penaeid shrimp, and established a foundation for further exploration of the roles of m6A modification in shrimp development and growth.

Impact of Dietary Administration of Seaweed Polysaccharide on Growth, Microbial Abundance, and Growth and Immune-Related Genes Expression of The Pacific Whiteleg Shrimp (Litopenaeus vannamei)

This work aims to determine the impact of dietary supplementation of polysaccharide, extracted from brown seaweeds Sargassum dentifolium on growth indices, feed utilization, biochemical compositions, microbial abundance, expressions of growth and immunity-related genes, and stress genes of the Pacific Whiteleg shrimp Litopenaeus vannamei. A total of 360 post-larvae of L. vannamei were randomly distributed into a 12-glass aquarium (40 L of each) at a stocking density of 30 shrimp with an initial weight of (0.0017 ± 0.001 g). During the 90-day experiment trial, all shrimp larvae were fed their respective diets at 10% of total body weight, three times a day. Three experimental diets were prepared with different seaweed polysaccharide (SWP) levels. The basal control diet had no polysaccharide level (SWP0), while SWP1, SWP2, and SWP3 contained polysaccharides at concentrations of 1, 2, and 3 g kg-1 diet, respectively. Diets supplemented with polysaccharide levels showed significant improvements in weight gain and survival rate, compared to the control diet. Whole-body biochemical composition and the microbial abundance (the total count of heterotrophic bacteria and Vibrio spp.) of L. vannamei showed significant differences among polysaccharide-treated diets compared to the control. At the end of the feeding experiment, the dietary supplementation of polysaccharide levels enhanced the expression of growth-related genes (Insulin-like growth factors (IGF-I, IGF-II), immune-related genes (β -Glucan-binding protein (β-Bgp), Prophenoloxidase (ProPO), Lysozyme (Lys), and Crustin), and stress genes (Superoxide dismutase (SOD) and Glutathione peroxidase (GPx) in the muscle tissue of L. vannamei. However, the current study concluded that the inclusion rate of 2 g kg-1 of polysaccharide as a dietary additive administration enhanced both weight gain and survival rate of L. vannamei, while the incorporation level of 3 g kg-1 reduces the abundance of pathogenic microbes and enhances the growth-, immunity- and stress-related gene expressions of L. vannamei.

Analisis Finansial Usaha Pembesaran Udang Vaname (Litopenaeus vannamei) pada Tambak Intensif di PT. Mitra Raya Cemerlang, Kabupaten Probolinggo

This pacific whiteleg shrimp (Litopenaeus vannamei) enlargement business has the name PT. Mitra Raya Cemerlang was established in 2017 in Koloran Hamlet, Klaseman Village, Gending District, Probolinggo Regency, East Java. This study aims to describe the marketing mix and analyze the business’s financial feasibility. Types of quantitative and qualitative research used a purposive sampling technique. The data analysis method used is marketing mix analysis and business feasibility by calculating short-term and long-term investment criteria. The results of the study indicate that in terms of the marketing mix, it is relatively simple to carry out directly at the place of business. Then in terms of business feasibility, in the short term, it is profitably seen from the R/C Ratio value of 3,785, BEP unit 31,533 kg, and BEP sales Rp. 2,459,591,932.98, and RTC 62.44% while in the long term it is feasible to see from the NPV value of Rp. 36,230,109,107, Net B/C Ratio 4.02, IRR 109%, and PP 1 where the sensitivity level is said to be not too sensitive.

Effect of sub-lethal ammonia and nitrite stress on autophagy and apoptosis in hepatopancreas of Pacific whiteleg shrimp Litopenaeusvannamei

Oxidative stress caused by ammonia and nitrite, affect the health and growth of aquaculture animals, results in oxidative damages. However, the toxic mechanism and pathogenesis of ammonia and nitrite to aquatic invertebrates are not completely clear. The present study was conducted to investigate the effects of sub-lethal ammonia and nitrite on autophagy and apoptosis in hepatopancreas of Pacific whiteleg shrimp Litopenaeus vannamei. Shrimps were exposed to sub-lethal ammonia (20 mg/L) and nitrite (20 mg/L) for 72 h, respectively. Hepatopancreas was collected for investigating the autophagy and apoptosis under stress conditions. The results showed that ammonia stress could induce up-regulated of autophagy (ATG3, ATG4, ATG10 and ATG12) and apoptosis (Caspase3 and P53) genes transcription. Nitrite stress could also induce up-regulated of autophagy (ATG3, ATG4, ATG5 and ATG10) and apoptosis (Caspase3) genes transcription. The expression of the autophagy related genes increased at first and then decreased with increasing exposure time. The atrophy, lysis, vacuolation of cell and other tissue damages in hepatopancreas were observed after 72h exposure to ammonia and nitrite. The results indicated that ammonia and nitrite stress could induce autophagy and apoptosis, and results in oxidative damage.

Combination of Nigella sativa and Phyllanthus niruri as An Immunostimulant for The Prevention of White Spot Disease in Litopenaeus vannamei

Pacific whiteleg shrimp (Litopenaeus vannamei) is a very important commodity, which accounts for almost 70% of the total world shrimp production. However, this production is still threatened by disease attacks, one of which is caused by white spot disease (WSD). Herbs are widely used as immunostimulants as an effort to prevent diseases. Black cumin (Nigella sativa) and stone breaker (Phyllanthus niruri) have long been known as excellent immunostimulants in human. This study aimed to evaluate the potential of N. sativa and its combination with P. niruri as an immunostimulant in L. vannamei for preventing WSD. Tested shrimp (±3.0 g) were treated by N. sativa (N), P. niruri (P) and the combination of both (1N:1P, 2/3N:1/3P, 3/4N:1/4P, 1/3N:2/3, 3/5N:2/5P, 1/4N: 3/4P, 2/5N:3/5P) through feed for 28 days. They were then infected by white spot syndrome virus (WSSV) and observed for 7 days. The parameters observed included immune response and production performance. N. sativa was able to reduce the mortality of test shrimp infected with WSSV, with an RPS value of 71%. N. sativa can be combined with P. niruri in the right composition (1/2N:1/2P and 2/3N:1/3P), while the other combinations are antagonistic. The administration of the best treatments in this study, relatively did not affect the value of total hemocyte count, phenoloxidase activity, respiratory burst activity, hemolymph clotting time and production performance of tested shrimp.

Length-weight relationship and condition factor of Pacific whiteleg shrimp (Litopenaeus vannamei, Boone, 1931) cultured in polyethylene lined pond

Pacific whiteleg shrimp Litopenaeus vannamei (Boone, 1931) cultured worldwide with developments and revolutions in culture ponds like spread polyethylene liner over earthen ponds. The length-weight relationships in shrimp, Litopenaeus vannamei was evaluated cultured in polyethylene (PE) lined ponds from Bhimpore village of Surat district (Gujarat). For this purpose, 500 specimens from pond were collected during 2021 and their length and weight were recorded as per the standard methods. The length and weight were noted 11.488-15.581 (13.393±0.035) cm and 12.26-31.22 (19.613±0.162) gm during study. The noted length frequency distribution for length group A-23, for B-377 and for C-100. The recorded correlation coefficient (r2) of the shrimp were 0.633 (A), 0.780 (B), 0.809 (C) and 0.906 (pooled) noted. The growth constant or regression coefficient (b) was observed 2.541, 2.812, 3.531 and 2.997 for length group A, B, C and pooled population. The growth constant depicted that growth of shrimp was isometric (b=3.0) and normal. A mean Fulton's condition factor value noted 0.808 (±0.002). These findings are clearly indicating that the growth of studied shrimp was normal and good in the polyethylene (PE) lined pond.

Supplementation of ex situ produced bioflocs improves immune response against AHPND in Pacific whiteleg shrimp (Litopenaeus vannamei) postlarvae.

The emergence of Vibrio diseases, including acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio spp., had resulted in heavy losses in global shrimp production. Biofloc technology is a closed aquaculture system developed as one of the sustainable solutions to increase system resilience in the shrimp industry. In this study, biofloc was formed externally (ex situ biofloc) with probiotics Bacillus sp. strain BME and Bacillus sp. strain BCE, diatom microalgae Chaetoceros calcitrans, and a consortium of nitrifying bacteria, in the ratio of 1:1:6:6 as a starter. The study showed that the ex situ biofloc supplementation in Pacific whiteleg shrimp (L. vannamei) postlarvae culture can increase the shrimp culture performance (shrimp survival and growth), reduce Vibrio counts in the water and shrimp body, and provide stimulation of the shrimp immune response through humoral immune responses, such as pattern recognition protein (C-type lectin) and melanization process (proPO). Overall, the results indicate that the supplementation of ex situ biofloc provided protection to shrimp under Vibrio infection, regardless of the timing of addition (before, simultaneously, or after addition of Vibrio sp. strain VPA). This suggests that the ex situ biofloc can be effective as a preventive and a supportive treatment against potential AHPND infection in L. vannamei postlarvae culture. Taken together, the ability of the ex situ biofloc to modulate immune-related gene expression and resistance of L. vannamei against potentially AHPND-causing Vibrio sp. strain makes it an effective aquaculture technology for infectious disease control in shrimp production with high-density and minimal water exchange culture. KEY POINTS: • Supplementation of ex situ produced biofloc in shrimp postlarvae culture. • Ex situ biofloc reduces Vibrio counts in the water and shrimp body. • Ex situ biofloc stimulates shrimp humoral immune responses and survival.

A newly identified NLR-like gene participates in bacteria and virus infection possibly through regulating hemocytes apoptosis in shrimp

The nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) play important roles in innate immunity. Previously, we identified an NLR-like gene, LvNLRPL1, and found that it participated in Vibrio infection and regulated hemocytes apoptosis in the Pacific whiteleg shrimp Litopenaeus vannamei. However, it is still unclear whether other NLR-like genes exist in shrimp and how they function during virus infection. In the present study, a novel NLR-like gene (LvNLRPL2) was identified and functionally characterized in L. vannamei. LvNLRPL2 was highly expressed in hemocytes and responsive to both Vibrio parahaemolyticus and white spot syndrome virus (WSSV) infection. Knockdown of LvNLRPL2 could markedly increase the proliferation of Vibrio and the mortality of shrimp infected with V. parahaemolyticus, whereas inhibit in vivo WSSV propagation in shrimp, indicating its distinct roles during Vibrio and WSSV infection. After LvNLRPL2 knockdown, the apoptotic rate of hemocytes increased, and the expression levels of LvCaspase 2, 3 and 5 were significantly up-regulated. In addition, LvNLRPL2 could form a hetero-dimer with LvNLRPL1 through their NACHT domains. These results suggest that LvNLRPL2 might resist bacterial infection while promote WSSV propagation by forming hetero-dimer with LvNLRPL1 and then inhibiting apoptosis of hemocytes. These data will be helpful for understanding the functions of NLR-like genes and their regulation mechanisms in crustaceans.

Optimal Dietary Crude Protein in Commercial Feeds for Shrimp and Halophytes in Marine Aquaponic Biofloc Systems

Formulated diets for animals is the primary source of nutrients in aquaponic systems that need to maintain beneficial bacteria as well as for plants. Dietary protein is one of the expensive macronutrients in fish diets, especially when fishmeal is used, and it is the source of nitrogen (N) for other biotic components. Biofloc has the potential to serve as the supplement diet for shrimp and reduce the need of expensive protein. However, it is not clear if low dietary protein will be adequate to support the three organisms (animals, plants, and bacteria) in an aquaponic system operated with biofloc technology. The aim of the present study was to investigate the effect of shrimp feed with different protein concentrations (30, 35, or 40%) on water quality and the growth performance of Pacific whiteleg shrimp (Litopenaeus vannamei) and three edible halophytic plants (Atriplex hortensis, Salsola komarovii, and Plantago coronopus) in biofloc-based marine aquaponics. The experiment was conducted for 12 weeks, the plants were harvested and seedlings transplanted every 4 weeks. Dietary protein content did not influence shrimp growth in the current study, indicating that feeds with lower protein concentrations can be used in biofloc-based marine aquaponic systems. During the early and mid-stages of cultivation, plants grew better when supplied diets with higher protein concentration, whereas no differences were observed for later harvests. Hence, for maximum production with mature systems or in the scenario of high concentration of nitrate, providing a higher protein concentration feed in the early stages of system start-up, and switching to a lower protein concentration feed in later stages of cultivation was recommended.

A Novel TRIM9 Protein Promotes NF-κB Activation Through Interacting With LvIMD in Shrimp During WSSV Infection

The TRIpartite Motif (TRIM) proteins play key roles in cell differentiation, apoptosis, development, autophagy, and innate immunity in vertebrates. In the present study, a novel TRIM9 homolog (designated as LvTRIM9-1) specifically expressed in the lymphoid organ of shrimp was identified from the Pacific whiteleg shrimp Litopenaeus vannamei. Its deduced amino acid sequence possesses the typical features of TRIM proteins, including a RING domain, two B-boxes, a coiled-coil domain, a FN3 domain, and a SPRY domain. The transcripts of LvTRIM9-1 were mainly located in the lymphoid tubules of the lymphoid organ. Knockdown of LvTRIM9-1 could apparently inhibit the transcriptions of some genes from white spot syndrome virus (WSSV) and reduce the viral propagation in the lymphoid organ. Overexpression of LvTRIM9-1 in mammalian cells could activate the promoter activity of NF-κB, and an in vivo experiment in shrimp showed that knockdown of LvTRIM9-1 reduced the expression of LvRelish in the lymphoid organ. Yeast two-hybridization and co-immunoprecipitation (Co-IP) assays confirmed that LvTRIM9-1 could directly interact with LvIMD, a key component of the IMD pathway, through its SPRY domain. These data suggest that LvTRIM9-1 could activate the IMD pathway in shrimp via interaction with LvIMD. This is the first evidence to show the regulation of a TRIM9 protein on the IMD pathway through its direct interaction with IMD, which will enrich our knowledge on the role of TRIM proteins in innate immunity of invertebrates.