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In the present study, quantitative real-time RT-PCR was used to monitor the transcriptional responses of seven key genes related to some innate immune pathways in shrimp postlarvae after being placed in a recirculating aquaculture system (RAS) with or without biofloc (BF or no-BF). Each system consisted of the main tank with 400 L of seawater and six glass aquariums (50 L each). Besides, the nucleotide sequences of myosin light chain (LvMyo) from Litopenaeus vannamei related to the phagocytosis pathway were described. The sequence analysis indicated that LvMyo is a conserved protein among crustaceans and is present in other arthropods. The transcriptional response to the treatments showed several expression patterns. The prophenoloxidase gene was up-regulated in both systems (P < 0.05) and was higher in BF than in no-BF (P < 0.01). Phagocytosis-related genes depicted differential expressions. LvMyo, Ras-associated binding 6, and Ras-related nuclear protein expressions were higher in BF than in no-BF (P < 0.05). Regarding antioxidant genes, glutathione peroxidase was up-regulated only in BF (P < 0.05). Superoxide dismutase expression was lower in BF at 12 h (P < 0.05), but higher at 24 h (P < 0.05). These findings suggest that biofloc modulates the transcription of genes related to the immune response in shrimp as an early response or at the mid-term. Besides, the biological filter in a RAS without biofloc seems to be able to maintain a bacterial population that promotes a lower but similar response to that induced in the biofloc system. [ABSTRACT FROM AUTHOR]

In the whiteleg shrimp Litopenaeus vannamei, the existence of six sinus gland peptides (SGPs) possessing vitellogenesis-inhibiting hormone (VIH) function has been previously demonstrated. Genomic and cDNA sequence information for two of these is already known. Here, we cloned cDNAs for the remaining three, i.e., those encoding Liv-SGP-A, -B, and -F. The deduced amino acid sequences were comprised of a signal peptide, a CHH precursor-related peptide, a mature peptide, and a C-terminal amidation signal. The genomic DNA for Liv-SGP-A, -B, -C, -F, and -G, was found to be organized as three exons and two introns. The insertion of the two introns were conserved in all VIH genes, with intron I being inserted six residues following the signal peptide, and intron II after the 40th residue of the mature peptide. We also quantified the relative simultaneous expression of Liv-SGP-A, -B, -C, -F, and -G in relation to molting and unilateral eyestalk ablation. The expression levels of each gene in the eyestalks of adults did not change significantly during molting or following unilateral eyestalk ablation. However, unilateral eyestalk ablation significantly decreased expression levels at 10 and 20 days for Liv-SGP-A and -C, and at 20 days for Liv-SGP-G in the eyestalks of subadults. This study has therefore clarified the genomic structure of the five major subtype I VIHs in L. vannamei, and elucidated their expression levels in the eyestalks in relation to molting and unilateral eyestalk ablation. [ABSTRACT FROM AUTHOR]

Infection with shrimp hemocyte iridescent virus (SHIV), a new virus of the family Iridoviridae isolated in China, results in a high mortality rate in white leg shrimp (Litopenaeus vannamei). The complete genome sequence of SHIV was determined and analyzed in this study. The genomic DNA was 165,809 bp long with 34.6% G+C content and 170 open reading frames (ORFs). Dotplot analysis showed that the longest repetitive region was 320 bp in length, including 11 repetitions of an 18-bp sequence and 3.1 repetitions of a 39-bp sequence. Two phylogenetic trees were constructed based on 27 or 16 concatenated sequences of proteins encoded by genes that are conserved between SHIV homologous and other iridescent viruses. The results of this study, suggest that SHIV should be considered a member of the proposed new genus “Xiairidovirus”. [ABSTRACT FROM AUTHOR]

In Brazil, studies and production of penaeid shrimp in a biofloc technology (BFT) system are recent, but the results point to a promising future. Research with feed restriction inducing compensatory growth in shrimps has been shown to be a technique that allows a saving of around 25% in the use of feed for shrimp production. It also allows the reduction of costs with salaries and adapts shrimp farming to the world demand for environmentally friendly production, with the reduction of nitrogen and phosphorus levels in its effluents, as well as lower water use in shrimp farming. In crustaceans, it has been shown that after a period of feed restriction, the animals show a pronounced compensatory growth when they return to a sufficient food source. Studies with the penaeid shrimp Litopenaeus vannamei reported the ability of the species to obtain a complete compensatory growth after short feeding periods (1 to 3 days) followed by feeding; These short periods of fasting presented a greater efficiency in the feed conversion besides the decrease in the concentration of phosphorus present in the aquatic environment, coming from the excreta. The adoption of a restriction program in the feeding using BFT may contribute to a reduction in operating costs, reduction of metabolic nutrients dissolved in water, and, consequently, an increase in the number of cycles in which the same water can be reused for production reducing production costs and improving productivity indices in shrimp farming. [ABSTRACT FROM AUTHOR]

The peritrophic membrane plays an important role in the defense system of the arthropod gut. The digestive tract is considered one of the major tissues targeted by white spot syndrome virus (WSSV) in shrimp. In this study, the nucleotide sequence encoding peritrophin-like protein of Litopenaeus vannamei (LvPT) was amplified from a yeast two-hybrid library of L. vannamei. The epitope peptide of LvPT was predicted with the GenScript OptimumAntigen™ design tool. An anti-LvPT polyclonal antibody was produced and shown to specifically bind a band at ~27 kDa, identified as LvPT. The LvPT protein was expressed and its concentration determined. LvPT dsRNA (4 μg per shrimp) was used to inhibit LvPT expression in shrimp, and a WSSV challenge experiment was then performed with reverse gavage. The pleopods, stomachs, and guts were collected from the shrimp at 0, 24, 48, and 72 h post-infection (hpi). Viral load quantification showed that the levels of WSSV were significantly lower in the pleopods, stomachs, and guts of shrimp after LvPT dsRNA interference than in those of the controls at 48 and 72 hpi. Our results imply that LvPT plays an important role during WSSV infection of the digestive tract. [ABSTRACT FROM AUTHOR]

Microcystins (MCs) in freshwater and marine waters released by toxin-producing cyanobacteria have negative impacts to the aquatic environment. This study aimed to investigate the effect of pure microcystin-LR on activity and transcript level of immune-related enzymes in the white shrimp Litopenaeus vannamei. After exposed to varying concentrations of pure microcystin-LR (MC-LR) for 30 days, the activity of superoxide dismutase (SOD), lysozyme (LZM), glutathione peroxidase (GPx), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP) and transcript level of cMn-sod, lzm, gpx were investigated in the hepatopancreas of white shrimp ( L. vannamei). Immune-related enzyme activities responded differently to MC-LR exposure. SOD, GPx, and POD activity in the hepatopancreas were activated in a concentration-dependent manner while LZM activity was significantly inhibited in the treatment groups. ACP and AKP activity showed an increase, followed by a decrease. The transcript levels of cMn-sod, lzm, and gpx were consistent with changes in their encoding enzyme activity. These results demonstrated that sub-chronical exposure to MC-LR induced the alteration of immune-related enzymes and corresponding genes in the hepatopancreas, which may help explain the presence of detoxification mechanisms in crustaceans and how they were protected from MC-LR stress for a long period of time. [ABSTRACT FROM AUTHOR]

Comparisons of natural mortality rates can be used to identify essential habitat and nursery areas for fishery species. We estimated and compared natural mortality rates of juvenile white shrimp Litopenaeus setiferus using length-frequency and mark-recapture data and attempted to identify factors that may affect these mortality rates. Daily instantaneous natural mortality rates (95 % confidence interval (CI)) obtained from length-frequency data by following individual cohorts were 0.043 (0.031-0.054) and 0.014 (0.0-0.039). Combining all length-frequency data, converting to age-frequency data, and using two types of catch-curve analyses yielded estimates of 0.069 (0.042-0.095) and 0.060 (0.046-0.073). Mark-recapture estimates obtained in a separate study from two ponds were 0.129 (0.054-0.203) and 0.014 (−0.048-0.076). These estimates are comparable to previously reported values for this species, but we are the first to report a measure of precision with our estimates. In the mark-recapture study, mortality rates appeared to be related to predator abundance in ponds and flooding patterns of the surrounding marsh. The only mortality rate significantly different from any of the other estimates was the lower of the two length-frequency estimates, but this result should be interpreted with caution because of the uncertainty in that estimate, relative imprecision of our estimates, and confounding factors between the methods we used to estimate mortality. Despite this caveat, the results from our study can be used to improve population models for L. setiferus and our understanding of the role of marsh habitats as nursery areas. [ABSTRACT FROM AUTHOR]

The choice of the source of organic carbon utilized in the fertilization of the farming system in bioflocs is important as it influences the nutritional composition of the bioflocs and should consider factors such as costs, local availability, and biodegradability. Therefore, the study aimed to evaluate the effect of brewery residues, an industrial by-product, as a source of organic carbon in bioflocs technology (BFT) farming system, on the performance of juvenile Litopenaeus schmitti (initial weight 0.64 ± 0.36 g) and compare it with two other sources already used for this purpose: sugarcane molasses and cassava flour. After 60 days of study, the superior growth performance of L. schmitti grown in fertilized BFT brewery residues system was evidenced by significantly higher final weight ( p < 0.05) in prawns grown in this system (2.47 ± 0.19 g) compared to the cultivated systems with sugarcane molasses (2.07 ± 0.23 g) and cassava flour (2.38 ± 0.27 g). The nutritional composition of bioflocs varied significantly according to the carbon source ( p < 0.05), with the largest concentrations of lipids (2.39 %) found in molasses and ash (71.56 %) for the brewery residues. The bioflocs formed in the brewery residues system had the highest density of diatoms (27 × 10 cells ml) and nematodes (6 org mL). The results showed that the brewery residues is a good source of organic carbon for L. schmitti farming in BFT system, presenting advantages in improving the zootechnical performance of the species and the low cost compared to other sources studied. [ABSTRACT FROM AUTHOR]

Bioassays are essential in detecting resistant animals based on standardized challenge tests. A controlled bioassay system for Infectious myonecrosis virus (IMNV) was developed through two methods of infection, by ingestion and injection, in Litopenaeus vannamei. For ingestion bioassays, shrimp (2-3.9 g) were exposed to four feeding infection treatments (feeding with infected tissue-FIT without stress; FITS-salinity stress; FITES-temperature and salinity stresses and FITA-alkalinity stress). No signs of disease were observed and 30 % of the animals were infected, with FITS treatment exhibited the higher proportion of infected animals ( p ≤ 0.05). In the injection treatments, a stock inoculum was quantified (viral load of 9.82 × 10 IMNV copies µg of total RNA) and a tenfold serial dilution was tested at 28 °C and, from 10 to 10 at 26 °C. Over 60 % of infected animals were obtained for dilutions between 10 and 10 at 28 °C, while at 26 °C; these values ranged from 30 to 50 %, with a clear effect of low water temperature in reducing the proportion of infected shrimp. In general, higher survival probabilities of infected shrimp were achieved 5 days after exposure, followed by a quick decrease at the tenth day post-inoculation. Median infectious dose (ID) was determined between 2.44 × 10 and 1.19 × 10 at 28 °C and between 1.76 × 10 and 1.28 × 10 at 26 °C for 15 days post-infection, respectively. Injection treatments based on known infectious dose were the most reliable method of estimating viral infectivity for IMNV selection. Moreover, FITS treatment was identified as an environmental risk factor, contributing to increase in IMNV infection prevalence. [ABSTRACT FROM AUTHOR]

This study was designed to determine the isoleucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50-0.70 g L). Six diets were formulated to contain 410 g kg crude protein with fish meal, peanut meal and pre-coated crystalline amino acids with different concentration of l-isoleucine (9.35, 11.85, 14.35, 16.85, 19.35, and 21.85 g kg dry diet, defined as diet I1, diet I2, diet I3, diet I4, diet I5 and diet I6, respectively.). Each diet was randomly assigned to triplicate treatments of 30 shrimps (0.43 ± 0.005 g), and the feed trial lasted for 8 weeks. The results indicated that the weight gain significantly increased with increasing isoleucine concentration up to 14.35 g kg (diet I3), whereas it was reduced in the treatments exceeding 16.85 g kg isoleucine (diet I4) significantly ( P < 0.05). Moreover, the highest body protein deposition and protein efficiency ratio, and the lowest feed conversion ratio, haemolymph aspartate aminotransferase and alanine aminotransferase activities were also found at treatment I3-I4 ( P < 0.05). And the haemolymph urea nitrogen concentration of shrimps-fed diet I6 was particularly higher than those fed with diets I1-I5 ( P < 0.05). The results of polynomial regression based on weight gain, feed efficiency and body protein deposition indicated that the optimal dietary isoleucine requirement for L. vannamei reared in low-salinity water was 15.95 g kg isoleucine of dry diet, correspondingly 38.81 g kg of dietary protein. [ABSTRACT FROM AUTHOR]

To quantify the response to selection, heritability and genetic correlations between weight and size of Litopenaeus vannamei, the body weight (BW), total length (TL), body length (BL), first abdominal segment depth (FASD), third abdominal segment depth (TASD), first abdominal segment width (FASW), and partial carapace length (PCL) of 5-month-old parents and of offspnng were measured by calculating seven body measunngs of offspnng produced by a nested mating design. Seventeen half-sib families and 42 full-sib families of L. vannamei were produced using artificial fertilization from 2-4 dams by each sire, and measured at around five months post-metamorphosis. The results show that hentabilities among vanous traits were high: 0.515±0.030 for body weight and 0.394±0.030 for total length. After one generation of selection. the selection response was 10.70% for offspring growth. In the 5 month, the realized heritability for weight was 0.296 for the offspnng generation. Genetic correlations between body weight and body size were highly variable. The results indicate that external morphological parameters can be applied dunng breeder selection for enhancing the growth without sacrificing animals for determining the body size and breed ability; and selective breeding can be improved significantly, simultaneously with increased production. [ABSTRACT FROM AUTHOR]

10-week feeding experiment was conducted to evaluate the nutritional value of menhaden oil (MO), soybean oil (SO) and soybean lecithin oil (SL) at different ratios (MO/SO/SL) in practical diets for juvenile Litopenaeus vannamei by determining their effects on survival, growth, blood chemistry and fatty acid composition of hepatopancreas and muscle tissue. Eight isonitrogenous and isolipidic diets were formulated using 3% MO(3/0/0), 3% SO(0/3/0), 3% SL(0/0/3), 1% MO + 1% SO + 1% SL (1/1/1), 1% SO + 2% SL (0/1/2), 1% MO + 2% SL (1/0/2), 2% SO + 1% SL (0/2/1) and 2% MO +1% SL (2/0/1), respectively. There were no significant differences in body weight gain among all treatments. However, shrimp fed diets with SL supplementation showed significantly ( P < 0.05) higher survival than those fed diets without SL supplementation (3% MO and 3% SO diets). The fatty acid (FA) composition of hepatopancreas and muscle tissue reflected, to a certain extent, FA composition of the test diets. Shrimp fed the 3% SL diets showed significantly ( P < 0.05) higher triglyceride (TG) concentration in serum than those fed the other experimental diets. Shrimp fed diets containing SL have relatively higher total cholesterol (TC) and phospholipid (PL) concentration in serum than those fed the diets without SL (3% MO and 3% SO). The results of the present investigation are encouraging and confirmed soybean lecithin supplement in shrimp practical diets, when sufficiently high levels of phospholipid are present, survival is enhanced. [ABSTRACT FROM AUTHOR]

The overall purpose of this study was to develop a quantitative model to assess the influence of L. setiferus predation on subtidal macrobenthic abundance cycles in an estuarine creek system. Subtidal macrobenthic populations in temperate marine soft-bottom environments are known to undergo seasonal abundance cycles. Although the factors responsible for driving these seasonal shifts in abundance are difficult to identify, both environmental and biological factors have received credit. Juvenile white shrimp ( Litopenaeus setiferus) are seasonally abundant epibenthic predators in the North Inlet estuary that have significant influence upon estuarine macrobenthic densities. Data generated from field and laboratory studies were combined with 20 years of long-term monitoring data to simulate seasonal variations in macrobenthos abundance under different levels of L. setiferus predation. Model simulations generated clear reductions in subtidal macrobenthos densities, confirming the role of L. setiferus as major consumers of macrobenthos. Model uncertainty was small, and model accuracy increased with shrimp density. In years with low or medium shrimp densities, predicted macrobenthos densities tended to be higher than those observed, yet predicted rates of decline still paralleled long-term observations. Model simulations best matched observed data for the representative high shrimp density year tested. Results indicate that variability in multiple factors, including L. setiferus predation, likely control macrobenthos abundance cycles. Predation by earlier-arriving epibenthic feeders may drive initial macrobenthos declines earlier in the year, with L. setiferus predation then intensifying and extending these declines throughout the summer and fall. This modeling approach is an important step toward understanding the role of multiple factors driving seasonal macrobenthos dynamics, and the L. setiferus population was tractable for examining the importance of epibenthic... [ABSTRACT FROM AUTHOR]

Electroporation of Litopenaeus schmitti embryos was used to transfer the pE300tiGH15 plasmid that contains the tilapia growth hormone gene (tiGH) complexed with a nuclear localization signal peptide into the zygotes. The gene construct was detected in 35 (36%) of the 98 larvae screened by PCR and Southern blot analyses. Western blot analyses revealed that 34% of the screened larvae expressed a single tiGH-specific band with the expected molecular mass (23.1 kDa). The development index and larval length indicated a significant growth enhancement from day 3 on after electroporation, with an average of 32% of the growth enhancement. To our knowledge, this is the first report on gene transfer enhanced growth in crustaceans. [ABSTRACT FROM AUTHOR]

White shrimp (Litopenaeus vannamei) population genetic structure from the eastern Pacific was determined by restriction fragment length polymorphism analysis of the mitochondrial DNA control region. Four localities were surveyed with four endonucleases (Alu I, Taq I, Spe I, Ssp I) yielding 48 composite haplotypes. White shrimp showed high average within-locality haplotype (0.823) and nucleotide (5.41%) diversities and also high average nucleotide divergence between all pairs of localities (0.73%). A mismatch analysis of pairwise differences between haplotypes indicated that white shrimp does not fit the sudden population expansion model. An analysis of molecular variance showed significant geographic variation in the frequencies of haplotypes (ΦST=0.1382, P<0.0001). Population differentiation may be maintained by a combination of physical, oceanographic, and biological factors acting as barriers to gene flow among localities. Because of its high polymorphism, the control region might be useful as a genetic marker for monitoring genetic diversity in aquaculture stocks. [ABSTRACT FROM AUTHOR]

Besides some mammals and a few model organisms, the presence of genetic variation in ovary or gonad development at ages before that of reproduction has not been established for marine oviparous species nor has the correlation with reproductive traits at maturity. In this investigation, ovary development was evaluated for genetic variability in a full-sib family structured population of subadult shrimp. The numbers of each oocyte type that were present were counted, measured, and used to evaluate the following traits: total oocyte number, mean oocytes diameter, and ovary maturity (OM). The total ovary area was also measured for each female. Genetic variation was assessed through the estimation of the parameter ‘heritability’. The heritability ( h 2) of total number of oocytes was zero, but large heritability values were seen for mean oocytes diameter ( h 2=0.57±0.27) and OM ( h 2=0.71±0.26). Family means correlations between traits in subadults with traits measured in their full-sibs when adults (days to first spawn, total number of spawns, total fecundity, and fecundity at first spawn) indicated the existence of some significant associations between reproductive traits at the two ages. These findings point toward an early genetic determination of reproductive capacity in this crustacean. [ABSTRACT FROM AUTHOR]

We report on the data mining of publicly available Litopenaeus vannamei expressed sequence tags (ESTs) to generate simple sequence repeat (SSRs) markers and on their transferability between related Penaeid shrimp species. Repeat motifs were found in 3.8% of the evaluated ESTs at a frequency of one repeat every 7.8 kb of sequence data. A total of 206 primer pairs were designed, and 112 loci were amplified with the highest success in L. vannamei. A high percentage (69%) of EST-SSRs were transferable within the genus Litopenaeus. More than half of the amplified products were polymorphic in a small testing panel of L. vannamei. Evaluation of those primers in a larger testing panel showed that 72% of the markers fit Hardy-Weinberg equilibrium, which shows their utility for population genetic analysis. Additionally, a set of 26 of the EST-SSRs were evaluated for Mendelian segregation. A high percentage of monomorphic markers (46%) proved to be polymorphic by singles-stranded conformational polymorphism analysis. Because of the high number of ESTs available in public databases, a data mining approach similar to the one outlined here might yield high numbers of SSR markers in many animal taxa. [ABSTRACT FROM AUTHOR]

The study assesses the concentration of seven heavy metals in the edible muscle of shrimp Litopenaeus vannamei and L. stylirostris from six coastal lagoons located in the northwest coast of Mexico. In each coastal lagoon, shrimp samples were obtained from local fishermen between September and October 2003. Concentrations of cadmium, cobalt, copper, iron, nickel, lead and zinc were assessed in the edible muscle of the shrimps. In conclusion, the observed differences between coastal lagoons may be a consequence of different concentrations of metals in the sediments and the environment, and/or by different metal bioavailability in those environments.

The article studies the effects of the heavy metals cadmium (Cd) and zinc (Zn) on the growth of Litopenaeus(L.) vannamei. It was observed that both Cd and Zn caused very obvious growth retardation in L. vannamel. Compared to the control shrimp, growth retardation of L. vannamei exposed to Cd was apparent after 14 days with both the 0.1 and 0.2 Cd/I treatments, and after 7 days with the 0.4 Cd/I treatment. Zn showed milder effects on the growth of L. vannamei compared to Cd. Growth retardation caused by both Cd and Zn appeared much earlier than the appearance of a significant decrease in food consumption.

Genetic variation and population structure of wild white shrimp (Litopenaeus vannamei) from 4 geographic locations from Mexico to Panamas were investigated using 5 microsatellite DNA loci. The genetic diversity between populations was indicated by the mean number of alleles per locus and mean observed heterozygosity, which ranged from 7.4 to 8.6 and from 0.241 to 0.388, respectively. Significant departures from Hardy-Weinberg equilibrium were found at most locations at each locus, with the exception Guatemala at Pvan0013, and were caused by high heterozygote deficiencies. Genetic differences between localities were detected by pairwise comparison based on allelic and genotypic frequencies, with the exception of locus Pvan1003. Significant pairwise FST values between locations and total FST showed that the white shrimp population is structured into subpopulations. However, population differentiation does not follow an isolation-by-distance model. Knowledge of the genetic diversity and structure of L. vannamei populations will be of interest for aquaculture and fisheries management to utilize and preserve aquatic biodiversity. [ABSTRACT FROM AUTHOR]

Genetic variability within the Cuban population of the white shrimp Litopenaeus schmitti (Burkenroad, 1936) was assessed using five microsatellite loci and samples collected from four sites (Batabanó, Cienfuegos, Tunas de Zaza, and Manzanillo) from November 1999 to March 2000. All loci were polymorphic, and a total of 80 alleles were found, 13 of them private alleles occurring only in a single population and always in low frequencies. The Cienfuegos sample had the highest observed heterozygosity (Ho=0.653), and the Tunas de Zaza sample had the lowest values (Ho=0.605), but there were no significant differences among samples in heterozygosity or in the mean numbers of alleles per locus (ranging from 11.0 to 11.6). Significant differentiation among populations was detected (FST=0.012, P<0.001). Low but significant FST values were revealed in pairwise comparisons between populations. Assignation tests correctly assigned high percentages of individuals to their original populations (74.5%) using a Bayesian approach. The significant differentiation among populations could be due to the restriction of gene flow among populations of L. schmitti and is concordant with previous allozyme studies on Cuban populations. [ABSTRACT FROM AUTHOR]

The article cites a study to determine acute toxicity of copper, zinc, iron and manganese and of mixtures copper-zinc and iron-manganese to Whiteleg Shrimp Litopenaeus vannamel Postlarvae. Results of the study revealed that no relation was observed between mortality and ecdysis in the iron and manganese bioassays. During the copper and iron assays, researchers observed the presence of particulates at the bottom of the experimental vessels. Researchers concluded that dissolved metals are supposed to be more toxic, because aquatic organisms more easily absorb them than the particulate fraction.

Oxyhemocyanin (OxyHc), blood protein, glucose, acylglycerol (AG), and lactate of Litopenaeus vannamei juveniles were investigated. Statistical analyses were done on baseline values for each metabolite and on OxyHc from shrimp cultured in outdoor (20-m2 ponds) and indoor (90-l tanks). The values obtained were compared with blood metabolites reported in the literature for L. vannamei maintained under similar conditions. Normal distribution was only found for samples from indoor shrimp. The distribution values for blood metabolites from shrimp cultured in outdoor ponds and indoor tanks were right or left skewed. OxyHc, blood proteins, and glucose levels were higher in shrimp cultured in outdoor ponds than those observed in shrimp maintained in indoor tanks. These differences were attributed to availability of live food in outdoor culture ponds. The OxyHc/protein ratio showed that 60% of blood protein is OxyHc in outdoor-cultured shrimp and was lower than in indoor-cultured shrimp, and this ratio was lower than that found (97%) in indoor-cultured shrimp. The type of food was identified as a dominant factor affecting blood metabolites. AG in outdoor-cultured shrimp was significantly lower than that observed in indoor-maintained shrimp. Blood lactate concentration of shrimp was not affected by the culture conditions. The blood levels for protein, glucose, and lactate reported here are similar to those reported previously for other crustacean species, indicating that these can be used as a reference for evaluating the physiological status of L. vannamei. When we compared the OxyHc, blood protein, glucose, and lactate levels of L. vannamei juveniles with other crustacean species, we observed that crabs, lobsters (low-activity species), and closed-thelycum shrimp species (mean-activity species) had lower values in comparison to those observed in open-thelycum shrimp species, including L. vannamei juveniles. Possibly the blood metabolites and OxyHc could be reflecting the morphological and physiological adaptation of crustaceans, because these metabolites will depend on energetic demands. [ABSTRACT FROM AUTHOR]

The article focuses on a study related to the mortality of a whiteleg shrimp, Litopenaeus Vannamei postlarvae, exposed under laboratory conditions to individual concentrations of Cadmium (Cd), mercury (Hg) and lead (Pb). Postlarvae were obtained from a commercial facility in Mexico and held for three days under laboratory conditions. No shrimp died in the controls run in parallel with the bioassays of postlarvae exposed to different concentrations of total Cd, Hg, and Pb. These metals accumulate to high levels in the tissues causing death of the test organisms. Statistical analysis showed that the probit of mortality had a positive linear relationship with each metal.

The article discusses the effects of ammonia on mortality and feeding of postlarvae shrimp litopenaeus vannamei. The whiteleg shrimp Litopenaeus vannamei is a tropical species that is geographically distributed from Sonora, Mexico, to northern Peru. This decapod is cultured in extensive, intensive, and semi-intensive systems and is, with Litopenaeus stylirostris, the most popular shrimp for aquaculture in Mexico and Central and South America countries. The rearing of L. vannamei in closed systems results in metabolic wastes (as ammonia) accumulating in the ponds, even with frequent water replacement.

The Pacific white shrimp Litopenaeus vannamei is the dominant crustacean species in global seafood mariculture. Understanding the genome and genetic architecture is useful for deciphering complex traits and accelerating the breeding program in shrimp. In this study, a genome survey was conducted and a high-density linkage map was constructed using a next-generation sequencing approach. The genome survey was used to identify preliminary genome characteristics and to generate a rough reference for linkage map construction. De novo SNP discovery resulted in 25,140 polymorphic markers. A total of 6,359 high-quality markers were selected for linkage map construction based on marker coverage among individuals and read depths. For the linkage map, a total of 6,146 markers spanning 4,271.43 cM were mapped to 44 sex-averaged linkage groups, with an average marker distance of 0.7 cM. An integration analysis linked 5,885 genome scaffolds and 1,504 BAC clones to the linkage map. Based on the high-density linkage map, several QTLs for body weight and body length were detected. This high-density genetic linkage map reveals basic genomic architecture and will be useful for comparative genomics research, genome assembly and genetic improvement of L. vannamei and other penaeid shrimp species. [ABSTRACT FROM AUTHOR]