Pacific White Shrimp Litopenaeus Vannamei Research Articles

Aquaporins in Pacific White Shrimp (Litopenaeus vannamei): Molecular Characterization, Expression Patterns, and Transcriptome Analysis in Response to Salinity Stress

Aquaporins (AQPs) are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. These proteins are vital for maintaining water homeostasis in living organisms. In mammals, thirteen aquaporins have been characterized, but in crustaceans, especially penaeid shrimp, the diversity, structure, and substrate specificity of these membrane channel proteins are largely unknown. We here presented the three types of AQPs from Litopenaeus vannamei based on genome and transcriptome sequencing. Phylogenetic analysis showed that each AQP separately represented members of aquaglyceroporins, classical aquaporins, and unorthodox aquaporins, thus they were named as LvAQP3, LvAQP4, and LvAQP11. The LvAqp4 was mostly expressed in hepatopancreas, stomach, and gill, meanwhile LvAqp3 and LvAqp11 were separately predominantly expressed in intestine and muscle, respectively. To investigate possible roles of aquaporins in osmoregulation, mRNA expression changes in mainly expressed tissues were analyzed after acute exposure or long-term acclimation to different salinities. The results revealed that the expression levels of aquaporins genes were significantly decreased in most tissues (except hepatopancreas) under salinity stress, though the expression patterns were variable among isoforms and tissues. Moreover, comparative transcriptome analysis indicated the combination roles of aquaglyceroporin and amino acid metabolism related genes and pathways in response to acute salinity changes in the intestine. This study opened new windows for future investigations and provided new insights into the role of aquaporins in osmoregulation in L. vannamei.

Supplementing Sulfate-Based Alginate Polysaccharide Improves Pacific White Shrimp (Litopenaeus vannamei) Fed Fishmeal Replacement with Cottonseed Protein Concentrate: Effects on Growth, Intestinal Health, and Disease Resistance

Sulfate-based alginate polysaccharide (SAP) is a novelty marine prebiotic. To investigate the beneficial effects of SAP in Pacific white shrimp (Litopenaeus vannamei) fed low-fishmeal diets, six diets (whole fishmeal group: FM; fishmeal replacement with cottonseed protein concentrate and SAP supplementary groups: SAP0, SAP1, SAP2, SAP3, and SAP4) were formulated and fed shrimp for 56 days. The results showed that SAP2 and SAP3 groups reached the best weight gain and specific growth rate ( P < 0.05 ). In serum, the activities of lysozyme and acid phosphatase showed the trend of firstly increased and then decreased ( P < 0.05 ). In the gut, the highest activities of trypsin, lipase, and amylase were found in SAP2 and SAP3 groups ( P < 0.05 ); the histological indexes gradually improved with SAP levels increased ( P < 0.05 ); sequencing of microbiota revealed that the composition and structure of microbiota have been improved, especially in the decreasing abundance of Vibrio, Pseudoalteromonas, and Candidatus Bacilloplasma at genus level. Besides, transcriptomics revealed a degree of similarity in differential gene expression patterns in shrimp; the comparison of RNA-Seq and qRT-PCR verified that SAP improved antioxidant and immunity in shrimp. The challenge revealed that SAP strengthened the resistance against Vibrio parahaemolyticus. Totally, the supplementary SAP to low-fishmeal diets improved growth, intestinal health, and disease resistance in shrimp. Based on the polynomial curve analysis of specific growth rate among SAPs groups, the optimum SAP supplementary level was 1.91%.

Replacement of Commercial Feed with Fresh Black Soldier Fly (Hermetia illucens) Larvae in Pacific White Shrimp (Litopenaeus vannamei)

This study evaluated survival, growth performance, digestive enzyme activities, intestinal histology, and antioxidant enzyme activities of the Pacific white shrimp (Litopenaeus vannamei), which were fed with five different diets, containing 0%, 25%, 50%, 75%, and 100% fresh black soldier fly larvae (BSFL), respectively, to replace commercial feed at an equal wet weight. The cultured experiment was lasted for 45 days, and the results showed that survival rate (SR), final body weight (FBW), and weight gain (WG) were negatively related with the replacement rate of fresh BSFL in the diet, where the maximum value was found in the BSFL 25% group, while the minimum value appeared in the BSFL 100% group. When BSFL replacement level was equal to or above 75%, the SR, FBW and WG were significantly decreased. However, hepatosomatic index (HSI) was increased with the increasing BSFL replacement level, which was significantly higher in BSFL 75% and BSFL 100% groups than the other groups. No significant differences on hepatopancreatic amylase and lipase activities of the shrimp were observed among all the groups. However, compared with the control group, protease activity in hepatopancreatic of the shrimp was significantly higher when up to 25% of commercial feed was replaced. The histological structure of the intestine gradually changed pathologically, such as tissue disruption, with increasing proportion of fresh BSFL in the diets. A significant reduction in intestinal fold height was found in the BSFL 100% group, and a decreased thickness of intestinal muscular was also observed in all treatment groups. The serum SOD and GSH-PX activities of shrimp in all treatment groups were significantly higher than that of the control group. In conclusion, replacing commercial feed up to 50% with fresh BSFL could be feasible for L. vannamei farming when growth performances, digestive enzyme activities, intestinal histology, and antioxidant enzymes were being considered.

Characterization of spray-dried carotenoprotein powder from Pacific white shrimp (Litopenaeus vannamei) shells and head waste extracted using papain: Antioxidant, spectroscopic, and microstructural properties

Spray-dried carotenoprotein powder from Pacific white shrimp shells (CPSS) and head (CPSH) waste extracted using papain enzyme were investigated for their antioxidant, spectroscopic, and microstructural properties. The enzymatic hydrolysis conditions were optimized through an experimental Box-Behnken design using response surface methodology (RSM). Optimum hydrolysis conditions to acquire a maximum degree of hydrolysis (DH) of 52.45% for CPSS and 55.36% for CPSH were the enzyme/substrate ratio (CPSS: 2 g/100 g; CPSH: 1.09 g/100 g), temperature (CPSS: 54.41 °C; CPSH: 46.23 °C), pH (CPSS: 6.82; CPSH: 7.22), and time (CPSS: 48.91 min; CPSH: 51.17 min). The analysis of the carotenoprotein powder indicated that protein content (86.16%), DPPH activity (89.55%), and FRAP (2230.5 μmol TE/mL) were higher in the CPSH compared to CPSS. The intensity of the β-sheets were higher in CPSH. The microstructure of the CPSS were rounder and wrinkle-free compared to CPSH powder. The study found that spray-dried carotenoprotein powder recovered from the head waste of Litopenaeus vannamei possessed excellent characteristics compared to shell waste and might be used for fortification and enrichment as a nutraceutical in the food processing industry.

Effects of the addition of oak (Quercus robur L.) and yucca (Yucca schidigera) on the water quality and growth performance of pacific white shrimp (Litopenaeus vannamei) cultured intensively in concrete tanks

AbstractThe application of mixed natural extracts from oak (Quercus robur L.) and yucca (Yucca Schidigera) (OY) in an intensive culture system for Pacific white shrimp (Litopenaeus vannamei) was able to improve the growth performance of shrimp and the quality of its rearing media. Twelve tanks sized 8 × 8 × 1.3 m were stocked with 500 post‐larvae m−2 per tank and treated with 2, 2.5, and 3 Kg Ha−1 of OY. Physical and chemical water parameters, including pH, dissolved oxygen, temperature, and salinity, were measured 4 times day−1 during the trial. Measurements of other chemical parameters, including Ammonia (NH3‐N), Nitrite (NO2‐N), and Nitrate (NO3‐N), were performed the second and sixth day after the addition of OY. The same measurements were conducted in the control treatment every seventh‐day post water exchange during the 90 days of the culture period. The growth performance parameters (biomass, final body weight, feed conversion ratio, survival rate, and percentage weight gain) and nutrient retention rate were evaluated after 90 days of shrimp culture. The utilization of OY significantly increased the final body weight (FBW), percentage weight gain (PWG), feed conversion ratio (FCR), survival rate (%), and the final biomass of shrimp. Different dose applications of OY significantly reduced the accumulation of ammonia (NH3‐N), nitrite (NO2‐N), and nitrate (NO3) in the rearing media compared to the control. However, there were no significant differences in protein, fat, ash, dry fiber, and water content among the shrimp treated with different addition levels of OY. This research concludes that the application of OY could maintain a safe level of ammonia and other nitrogen metabolites in the rearing media and enhance the growth performance of shrimp cultured in intensive production systems using commercial concrete tanks.

Genome-Wide Analysis Indicates a Complete Prostaglandin Pathway from Synthesis to Inactivation in Pacific White Shrimp, Litopenaeus vannamei.

Prostaglandins (PGs) play many essential roles in the development, immunity, metabolism, and reproduction of animals. In vertebrates, arachidonic acid (ARA) is generally converted to prostaglandin G2 (PGG2) and H2 (PGH2) by cyclooxygenase (COX); then, various biologically active PGs are produced through different downstream prostaglandin synthases (PGSs), while PGs are inactivated by 15-hydroxyprostaglandin dehydrogenase (PGDH). However, there is very limited knowledge of the PG biochemical pathways in invertebrates, particularly for crustaceans. In this study, nine genes involved in the prostaglandin pathway, including a COX, seven PGSs (PGES, PGES2, PGDS1/2, PGFS, AKR1C3, and TXA2S), and a PGDH were identified based on the Pacific white shrimp (Litopenaeus vannamei) genome, indicating a more complete PG pathway from synthesis to inactivation in crustaceans than in insects and mollusks. The homologous genes are conserved in amino acid sequences and structural domains, similar to those of related species. The expression patterns of these genes were further analyzed in a variety of tissues and developmental processes by RNA sequencing and quantitative real-time PCR. The mRNA expression of PGES was relatively stable in various tissues, while other genes were specifically expressed in distant tissues. During embryo development to post-larvae, COX, PGDS1, GDS2, and AKR1C3 expressions increased significantly, and increasing trends were also observed on PGES, PGDS2, and AKR1C3 at the post-molting stage. During the ovarian maturation, decreasing trends were found on PGES1, PGDS2, and PGDH in the hepatopancreas, but all gene expressions remained relatively stable in ovaries. In conclusion, this study provides basic knowledge for the synthesis and inactivation pathway of PG in crustaceans, which may contribute to the understanding of their regulatory mechanism in ontogenetic development and reproduction.

Effects of Pelleted and Extruded Diets of Different Protein Levels on Growth, Digestive Enzyme Activity, Antioxidant Capacity, Nonspecific Immunity, and Ammonia‐N Stress Tolerance of Postlarval Pacific White Shrimp

AbstractThe present study was conducted to evaluate the effects of pelleted and extruded diets of different protein levels on the growth performance, digestive enzyme activity, antioxidant capacity, nonspecific immunity, and ammonia‐N stress tolerance of postlarval Pacific white shrimp Litopenaeus vannamei. The shrimp were fed six diets, including extruded diets with dietary 41% protein (E41), 43% protein (E43), and 46% protein (E46) and pelleted diets with dietary 41% protein (P41), 43% protein (P43), and 46% protein (P46), for 60 d. The Pacific white shrimp that consumed diets with 43% and 46% protein had significantly higher final body weight, specific growth rate, and protease activity than those that consumed diets with 41% protein regardless of processing methods. The shrimp that consumed the extruded diets showed significantly higher final body weight, specific growth rate, and protease activity than those that consumed the pelleted diets when 41% and 43% protein were supplemented in the diets. The shrimp that consumed the extruded diets had significantly higher alpha‐amylase activity in the hepatopancreas than those that consumed the pelleted diets regardless of dietary protein levels. The extruded diet and dietary 43% and 46% protein showed higher activities of antioxidant enzymes, nonspecific immunity‐related indices, and acute ammonia‐N stress resistance when compared with the pelleted diets and dietary 41% protein, respectively. These results suggest that dietary 43% and 46% protein can promote the growth performance and enhance the digestive and antioxidant capacities, nonspecific immunity, and ammonia‐N resistance of Pacific white shrimp and that the extrusion process is a better method for promoting the growth performance and enhancing the digestive capacity, activities of antioxidant enzymes, nonspecific immunity, and ammonia‐N resistance of Pacific white shrimp.

Cold Plasma: An Alternative in Litopenaeus vannamei Shrimp Preservation

This study aimed evaluating the effects of cold plasma on the quality attributes of Pacific white shrimp (Litopenaeus vannamei). Shrimp were divided into 4 sample groups: one control and the remaining groups subjected to cold plasma at frequencies of 5, 10, and 15 kHz, respectively, during 10 minutes of application followed by evaluation of chemical, physical, microbiological, and sensorial characteristics. Cold plasma contributed significantly to the maintenance of shrimp quality during storage, delaying the melanization process, microbial growth, improving the physicochemical and sensorial qualities of the samples. Exposure of white shrimp to non-thermal plasma at 15 kHz promoted better physicochemical, microbiological, and sensorial results, and increased the shelf life of samples by 5 days, suggesting that the treatment is effective to preserve the quality of shrimp.

Hydrolysed fish protein powder is better at the growth performance, hepatopancreas and intestinal development of Pacific white shrimp (Litopenaeus vannamei)

The effect of hydrolysed fish protein powder (HFP) on the growth, aspartate transaminase (AST) and alanine transaminase (ALT) content in the serum, malondialdehyde (MDA) and superoxide dismutase (SOD) content in the hepatopancreas, total protease, trypsin, and chymotrypsin in the intestine of Pacific white shrimp (Litopenaeus vannamei) was assessed after an 8-week experiment. Pacific white shrimps were fed six isonitrogenous (39%) and isolipidic (8%) diets with 0% (CT), 1% (T1), 2% (T2), 2.5% (T3), 3% (T4) and 4% (T5) HFP. A positive effect on weight gain rate, survival rate and feed conversion ratio was observed in shrimp fed HFP diets. In the serum, AST and ALT levels were significantly high in the T1 group compared to the other groups (P < 0.05). Total protease, trypsin and chymotrypsin were significantly high in the T4 group than in the CT group (P < 0.05). The insulin-like growth factor-I mRNA expression level in the intestine, hepatopancreas and muscle were significantly high in shrimp fed HFP diet compared to the CT group (P < 0.05). Muribaculaceae, Lactobacillus, and Lachnospiraceae were the most abundant bacteria at the genus level in the intestine. Results from this study suggest HFP has a positive effect on the growth and intestinal development of Pacific white shrimp.

Responses of lipid metabolism and lipidomics in the hepatopancreas of Pacific white shrimp Litopenaeus vannamei to microcystin-LR exposure

Microcystin-LR (MC-LR) is a toxic substance that threatens the health of aquatic animals. Hepatopancreas is the target organ of MC-LR toxicity. In this study, we investigated the effects of MC-LR on hepatopancreas lipid metabolism and lipidomic responses in Litopenaeus vannamei. After MC-LR exposure for 72 h, the hepatopancreas showed obvious tissue damage, and the activities of several lipase isoenzymes were decreased. Furthermore, the relative gene expression levels of lipolysis (CPT1, AMPKα), lipogenesis (SREBP, FAS, ACC, 6PGD), and long-chain fatty acid β-oxidation (ACDL, ACDVL, ACBP) were increased. MC-LR exposure also affected lipidomics homeostasis. Specifically, the levels of glycerophospholipids (phosphatidylcholine, phosphatidic acid, lyso-phosphatidylcholine, lyso-phosphatidylethanolamine, lyso-phosphatidylglycerol), sphingolipids (sphingomyelin and ceramides) and cholesteryl ester were increased, and those of phosphatidylinositol and triglyceride were decreased. The significantly altered lipid molecules were mainly associated with the pathways of lipid and fatty acid metabolism and autophagy. These results reveal that MC-LR exposure influences lipid metabolism and lipidomic homeostasis in the shrimp hepatopancreas.

Classical aquaporins from Pacific white shrimp (Litopenaeus vannamei): Molecular characterization and expression analysis in hypersalinity

Aquaporins (AQPs) are major intrinsic proteins that facilitate the transport of water, small solutes, and ions through membranes. In mammals, the classical aquaporin AQP4 plays a central role in the preservation of central nervous system (CNS) water homeostasis. Litopenaeus vannamei is a typical euryhaline crustacean, with a salinity tolerance range of 0.5–78. Compared to those reared at low-salinity, shrimps cultured at high-salinity have better taste and qualities, but slower growth, lower product yield, and higher mortality. Thus, there is an urgent need to research the osmoregulation of L. vannamei under high-salinity. Previous studies mainly focus on the osmoregulation of gill and hepatopancreas, whereas there is a lack of research on the osmoregulatory roles of CNS in L. vannamei. In the current study, we first presented another two classical AQPs from L. vannamei, of which the arthropod-specific big brain aquaporin (LvBib) was expressed as C-terminal splice variants (LvBib_L and LvBib_S), and the aquaporin-like protein (LvAqpl) was a new type of aquaporin in crustaceans. Tissue distribution revealed that LvAqp4, LvAqpl, and LvBib_L were mostly expressed in the CNS of brain and thoracic ganglion. Then, the expression pattern of aquaporins in brain and thoracic ganglion were examined under both acute and chronic high-salinity stresses. The LvAqpl was found to be down-regulated in both tissues in the two experiments; LvAqp4 was elevated in both tissues under acute stress, whereas it was decreased in the thoracic ganglion during early periods of adaption to high-salinity; LvBib_L was up-regulated in brain but down-regulated in thoracic ganglion under acute stress, whereas it showed the opposite expression pattern during chronic stress. The results suggest that these aquaporins have an important role in the CNS response to high-salinity challenge. Our study provides a base for future mechanistic studies on the role of classical aquaporins in osmoregulation.

Single-Cell Ribonucleic Acid Sequencing Clarifies Cold Tolerance Mechanisms in the Pacific White Shrimp (Litopenaeus Vannamei).

To characterize the cold tolerance mechanism of the Pacific white shrimp (Litopenaeus vannamei), we performed single-cell RNA sequencing (scRNA-seq) of ∼5185 hepatopancreas cells from cold-tolerant (Lv-T) and common (Lv-C) L. vannamei at preferred and low temperatures (28°C and 10°C, respectively). The cells fell into 10 clusters and 4 cell types: embryonic, resorptive, blister-like, and fibrillar. We identified differentially expressed genes between Lv-T and Lv-C, which were mainly associated with the terms “immune system,” “cytoskeleton,” “antioxidant system,” “digestive enzyme,” and “detoxification,” as well as the pathways “metabolic pathways of oxidative phosphorylation,” “metabolism of xenobiotics by cytochrome P450,” “chemical carcinogenesis,” “drug metabolism-cytochrome P450,” and “fatty acid metabolism.” Reconstruction of fibrillar cell trajectories showed that, under low temperature stress, hepatopancreas cells had two distinct fates, cell fate 1 and cell fate 2. Cell fate 1 was mainly involved in signal transduction and sensory organ development. Cell fate 2 was mainly involved in metabolic processes. This study preliminarily clarifies the molecular mechanisms underlying cold tolerance in L. vannamei, which will be useful for the breeding of shrimp with greater cold tolerance.

Histopathological of the hepatopancreas of Pacific white shrimp (Litopenaeus vannamei) infected by white feces disease

The high production of Pacific white shrimp (Litopenaeus vannamei) in Pidie Jaya impacts water quality decline around the ponds due to aquaculture waste. This condition causes shrimp to be susceptible to diseases, one of which is white feces disease (WFD). The objective of the study is to determine the level of hepatopancreatic damage caused by WFD through histopathological performance. Four shrimp samples were taken randomly from two semi-intensive ponds in Meurah Dua District, Pidie Jaya Regency, Aceh, Indonesia. The results showed that the histopathology in the hepatopancreas was severely damaged. The damages include vacuolization, fat degeneration, and necrosis in ponds with higher ammonia concentrations. According to pH, temperature, salinity, and ammonia concentrations, ponds near residential areas were more polluted than ponds far from residential areas. This condition is projected by the more damaged histopathological obstruction of the shrimp’s hepatopancreas.

Dietary recombinant human lysozyme improves the growth, intestinal health, immunity and disease resistance of Pacific white shrimp Litopenaeus vannamei

The present study was conducted to investigate the effects of dietary recombinant human lysozyme (RHL) on the growth, immune response, anti-oxidative activity, intestinal morphology, intestinal microflora and disease resistance of shrimp Litopenaeus vannamei. Shrimps with an initial body weight of 2.36 ± 0.02 g were fed diets supplemented with 0 (control group, R0), 0.0025% (R1), 0.005% (R2), 0.01% (R3), 0.02% (R4) and 0.04% (R5) of RHL, respectively. After a 10-week feeding trial, the final body weight, survival rate, weight gain ratio and protein efficiency rate of the shrimps in dietary RHL supplemented groups were significantly higher than that in the control group, while feed conversion ratio was significantly lower (P < 0.05). The total haemocyte count, total anti-oxidative capacity, respiratory burst, activities of phagocytosis, nitric oxide synthase, phenol oxidase and lysozyme in serum were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Meanwhile, the intestinal pile height and wall thickness were significantly higher in dietary RHL supplemented groups than those in the control group (P < 0.05). Dietary RHL significantly improved the expressions of immune-related genes in gill, such as lipopolysaccharide-β-glucan binding protein, Toll, immune deficiency, heat shock protein 70 and Crustin (P < 0.05). The abundance of proteobacteria and bacteroidetes in intestine was higher, while the abundance of firmicutes and cyanobacteria was lower than those in the control group at the phylum level. In addition, dietary RHL supplementation significantly improved the protective ability of shrimp against V. parahaemolyticus infection (P < 0.05). Based on the broken-line model analysis for weight gain ratio after the feeding trial, the optimal level of dietary RHL supplementation for shrimp was estimated to be 0.006375%.

Effects of Dietary Yeast Culture on Health Status in Digestive Tract of Juvenile Pacific White Shrimp Litopenaeus Vannamei

Effects of Dietary Yeast Culture on Health Status in Digestive Tract of Juvenile Pacific White Shrimp Litopenaeus Vannamei

In Silico Analysis of the Cross-Reactivity of Pacific White Shrimp (&amp;lt;i&amp;gt;Litopenaeus vannamei&amp;lt;/i&amp;gt;) Allergens with Other Arthropod Species

This study provided new data in the area of cross-reactivity for Pacific white shrimp (Litopenaeus vannamei). Although the cross-reactivity between the most prominent allergenic proteins of shrimp and other crustaceans has been extensively studied, few data are showing the frequency of arthropod-shrimp Litopenaeus vannamei cosensitization in an in silico analysis. A comparative analysis of “typical and non-typical” shrimp L. vannamei allergens with other species was achieved, revealing new allergens and previously characterized shrimp allergens, which validated the comprehensive identification approach used in this study. Importantly, up to 192, amino acid sequences were identified that had matches to shrimp L. vannamei allergens that matched allergenic proteins in mites, insects, fish, bacteria, mammals, birds, and plants.

Evaluation of Nutrient Removal Efficiency with Chitosan: Nutrient Composition and Bacterial Removal in Effluents of Nile Tilapia (Oreochromis niloticus) in the Hatchery

Effluents from aquaculture systems contain large volumes of chemical substances and microbial load such as polychlorinated biphenyls and antibiotics that are often used to control infection and pathogenic bacteria originating from feed or water. These substances, if discharged, create pollution in the aquatic environment. Mitigating this problem requires implementing appropriate treatment methods. This study investigated the efficiency of uptake of nutrients in the wastewater and reduction of microbial pollution by chitosan. This product is a linear polysaccharide composed of β-linked D-glucosamine and N-acetyl-D-glucosamine and can be extracted from the shells of shrimps, lobsters, crabs and other crustaceans that are discarded in bulk quantities by seafood restaurants. The performance of laboratory-produced chitosan (S1) which was prepared from shells of Pacific white leg shrimp (Litopenaeus vannamei) was compared with that of the commercial grade chitosan (S2). While the latter was more effective in nitrogen and phosphorus removal and reduction of total faecal coliform, the two products were comparable in the uptake of minerals from the effluents from a tilapia culture system. The results showed that S1 and S2 adsorbed the nutrients from aquaculture effluents, especially ammonia (NH4 + ), nitrite (NO2 - ), nitrate (NO3 - ) and phosphate (PO4 3-). However, differences were evident in terms of the efficiency of their removal and duration of treatment required for the purpose. In this respect, S2 performed better. Moreover, the anti-bacterial activity of S2 was higher than that of S1, and this appeared to be linked to differences in surface features of the two products. The chitosan extracted from shrimp waste and processed locally provides a low-cost solution to the environmental problems caused by aquaculture effluents.

Construction of a genetic linkage map, QTLs mapping for low salinity and growth-related traits and identification of the candidate genes in Pacific white shrimp (Litopenaeus vannamei)

Low-salinity tolerance and growth are crucial economic traits of shrimp in areas with low-salinity water. In the current study, an F1 full-sib family of Pacific white shrimp (Litopenaeus vannamei) was obtained by the “semidirectional cross” method, and 2 parents and 146 progenies were genotyped using double-digest restriction site-associated DNA sequencing technology (ddRAD-Seq). A total of 3335 high-quality markers were identified and used to construct a genetic linkage map. This genetic map comprised 48 linkage groups (LGs), and the total map length spanned 3954.462 centimorgan (cM) with an average marker interval of 1.186 cM. Three quantitative trait loci (QTLs) for low-salinity tolerance and 3 QTLs for growth (body weight) were detected under the condition of restricted logarithmic odds (LOD) score ≥ 2.50. With the assistance of the genome of L. vannamei and relevant annotations, 3 potential growth-related genes (sob, TJP1 and ZBTB24) and 3 low-salinity response candidate genes (Rnf168, CNOT2 and RPB3) were identified from the genomic scaffolds. Moreover, the qPCR results showed that the expression levels of the 3 candidate genes were significantly affected by low-salinity stress, indicating that they possibly play an important role in low-salinity stress. Here, we present the first report of mapping of low-salinity tolerance QTLs in the genetic mapping of L. vannamei, which will be beneficial for the selection of shrimp breeding markers and might help promote the study of the L. vannamei genome.

MiR-10c Facilitates White Spot Syndrome Virus Infection by Targeting Toll3 in Litopenaeus vannemei.

Toll-like receptors (TLRs) are canonical cell membrane receptors functioning to recognize pathogens and transduce signals to activate immune responses. It has been known that Toll3 in Pacific white shrimp Litopenaeus vannamei (LvToll3) plays a critical role in antiviral immunity by inducing the transcription of interferon regulatory factor (IRF), which mediates a signaling axis that is similar to the interferon system of vertebrates. However, the regulatory mechanism of the Toll3-IRF signaling is still unclear. In this study, a novel microRNA (miRNA) of miR-10 family, temporarily named as miR-10c, was identified from L. vannamei. miR-10c may play a nonnegligible regulatory role in shrimp immune responses since it was constitutively expressed in all detected tissues and transcriptionally induced by immune stimulation. Functional analysis validated that miR-10c could target LvToll3 to inhibit its expression, through which miR-10c blocked the nuclear translocation of IRF and facilitated white spot syndrome virus (WSSV) infection. To our knowledge, the present study revealed the first report of a Toll targeted by miRNA in crustaceans and provided a solid evidence base for supporting the role of LvToll3 in antiviral defense by activating IRF signaling in L. vannamei. Identification of the miR-10c/Toll3/IRF regulatory axis in shrimp provides new insights into the participation of miRNA in the regulation of immune responses and contributes to in-depth understanding of the mechanisms of Toll-induced immune responses in L. vannamei.

Assessment of elemental profiling combined with chemometrics for authenticating the geographical origins of Pacific white shrimp (Litopenaeus vannamei)

Pacific white shrimp (Litopenaeus vannamei) is an important aquaculture species worldwide, and there is a growing concern over misdescribed shrimp products, particularly over their geographical origins. Shrimp samples were collected from 12 locations in northern and southern China to develop traceability methods in identifying their geographic origins. In one of the sampling sites, shrimp were collected from five farms using the same water source but feeding with different brands of feed to investigate the effect of feed on the elemental compositions of shrimp. Totally 35 elements (Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Y, U, Li, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Ag, Cd, Cs, Ba, and Pb) were detected in both shrimp and feed. Only Cd and Tb in shrimp were positively correlated with those in the feed. Moreover, 24 elements (Li, Al, V, Fe, As, Rb, Sr, Cd, Pb, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, and Y) in shrimp were significantly different between northern and southern China. Elements As, Fe, Pb, Rb, Cs, and U, selected by stepwise discriminant analysis (SDA), were used to create a new dataset (SSDAs dataset) to compare with the entire dataset (ATEs dataset) in discrimination analyses. Classification tools, including linear discriminant analysis (LDA), k-nearest neighbor (KNN), and random forest (RF) were used to create a discrimination model to authenticate shrimp provenance based on the ATEs and SSDAs datasets. The highest discrimination rate was achieved with RF using the SSDAs dataset, which achieved an overall correct discrimination rate of 100%, a cross-validation rate of 98.78%, and a predictive discrimination rate of 100%. Therefore, elemental profiling combined with chemometrics is a promising method which can be used to identify shrimp provenance.