Female Swimming Crab Research Articles

Mating behaviour and cholesterol nutritional strategies promoted ovarian development of female swimming crab (Portunus trituberculatus).

Female crabs enter a stage of rapid ovarian development after mating, and cholesterol is a substrate for steroid hormone synthesis. Therefore, in this experiment, an 8-week feeding trial was conducted to investigate the effects of mating treatments (mated crab and unmated crab) and three dietary cholesterol levels (0·09 %, 0·79 % and 1·40 %) on ovarian development, cholesterol metabolism and steroid hormones metabolism of adult female swimming crab (Portunus trituberculatus). The results indicated that crabs fed the diet with 0·79 % cholesterol significantly increased gonadosomatic index (GSI) and vitellogenin (VTG) content than other treatments in the same mating status. Moreover, mated crabs had markedly increased GSI and VTG content in the ovary and hepatopancreas than unmated crabs. The histological observation found that exogenous vitellogenic oocytes appeared in the mated crabs, while previtellogenic oocytes and endogenous vitellogenic oocytes were the primary oocytes in unmated crabs. The transmission electron microscopy analysis showed that when fed diet with 0·79 % cholesterol, the unmated crabs contained more rough endoplasmic reticulum and mated crabs had higher yolk content than other treatments. Furthermore, mating treatment and dietary 0·79 % cholesterol level both promoted cholesterol deposition by up-regulation of the mRNA and protein expression levels of class B scavenger receptors 1 (Srb1), while stimulating the secretion of steroid hormones by up-regulation of the mRNA and protein expression of steroidogenic acute regulatory protein (Star). Overall, the present results indicated that mating behaviour plays a leading role in promoting ovarian development, and dietary 0·79 % cholesterol level can further promote ovarian development after mating.

Effect of dietary β‐carotene supplementation on growth and antioxidant capability of female swimming crab Portunus trituberculatus

AbstractDietary supplementation with synthetic β‐carotene was investigated in this study to assess its impact on gonad development, antioxidant status, color parameters, and carotenoid composition in adult female swimming crab (Portunus trituberculatus). Four diets, designated as Diet 1 to 4, were formulated to contain 3.07, 53.78, 103.23, and 205.22 mg/kg dry diets of synthetic β‐carotene. The findings revealed the following: (1) No significant differences in body weights or feed utilization were observed, indicating that β‐carotene did not significantly enhance the growth of adult P. trituberculatus. (2) The inclusion of 50–100 mg/kg β‐carotene in the diets led to improvements in antioxidant capacity indicators (T‐AOC, MDA) and immune‐related parameters (AKP, ACP) in both hepatopancreas and hemolymph. (3) Notably, the redness of ovaries and hepatopancreas increased significantly with higher dietary β‐carotene supplementation for color enhancement. In conclusion, incorporating β‐carotene into the diet enhanced the antioxidative capability, nonspecific immunity, and tissue carotenoid contents in adult female P. trituberculatus, and the optimal level of dietary synthetic β‐carotene supplementation for adult female P. trituberculatus was suggested to be around 100 mg/kg.

Nutrient Composition of Ovary, Hepatopancreas and Muscle Tissues in Relation to Ovarian Development Stage of Female Swimming Crab, Portunus trituberculatus.

The swimming crab Portunus trituberculatus is one of the most important economic species in China and its mature ovary often determines its commercial value and production. Although the ovary maturation of crustaceans is generally affected by exogenous nutrition, the specific nutritional needs of ovary maturation of P. trituberculatus are poorly understood. To this end, we collected the P. trituberculatus samples with five ovarian maturation stages and measured their biochemical composition of the ovary, hepatopancreas, and muscle at each ovarian developmental stage. We further analyzed their relation to the ovarian developmental stage of P. trituberculatus by principal components analysis (PCA). We found the levels of branched-chain amino acids, long-chain polyunsaturated fatty acids (LC-PUFA), and monounsaturated fatty acids (MUFAs) in the ovary and hepatopancreas increased during the ovary maturation process, and also passively correlated with ovarian developmental stage, which highlights the necessity of these specific nutrients for oogenesis and for improving the nutrient quality of crabs. In addition, we found an increasing tendency of carotenoid content and phosphatidylcholine in phospholipid in the ovary from the pre-developmental stage to the proliferative stage, but not in the hepatopancreas and muscle, which highlights the possible involvement of carotenoids during the rapid oocyte development process. Our study may provide valuable information for developing a suitable broodstock diet that promotes the ovarian maturation of adult P. trituberculatus and ensures high-quality larval production.

Differences in Agonistic Behavior and Energy Metabolism between Male and Female Swimming Crab Portunus trituberculatus Based on the Analysis of Boldness.

Simple SummaryBoldness is a widely studied personality trait that is positively related to an individual’s willingness to fight. To explore the agonistic behavior between female and male crabs with different degrees of boldness, we quantified the boldness of females and males using a behavior observation system and used the experimentally determined boldness and classification. The results showed that boldness affected the agonistic behavior between female and male swimming crabs, the fighting willingness and capacity of male crabs is higher than that of female individuals and is higher in bold crabs than in shy individuals. Energy reserves and metabolic rates may be one of the factors affecting the agonistic behavior in crabs and that the agonistic behavior resulted in significant changes in key energy metabolites.Individual differences in metabolism and agonistic behavior have been a key research area in evolution and ecology recently. In this study, we investigated the boldness of swimming crabs Portunus trituberculatus and explored the agonistic behavior between female and male crabs, specifically examining competitions between bold females vs. bold males (BF–BM), bold females vs. shy males (BF–SM), shy females vs. shy males (SF–SM), and shy females vs. bold males (SF_BM) and its relationship with energy metabolism. The main results revealed the following: There was no significant difference in boldness between females and males, while there were more bold individuals than shy in both females and males. Bold individuals initiated significantly more fights than shy individuals, and male initiators won significantly more fights than female initiators. The duration and intensity of fight between bold individuals was significantly higher than fights between shy individuals. For males, the concentration of glucose in the hemolymph was significantly higher in shy crabs than bold crabs, while there was no significant difference between shy and bold individuals in females. After fighting, the concentration of glycogen in claws was lower than that before fighting, and the concentrations of glucose and lactate in hemolymph were significantly higher after fighting than before. We found that the fighting willingness and ability were higher in male crabs than females and higher in bold crabs than shy. Fighting ability varied between sexes and was influenced by boldness and energy state.

Integrated physiological, transcriptome and metabolome analyses of the hepatopancreas of the female swimming crab Portunus trituberculatus under ammonia exposure

Ammonia is a common environmental pollutant in aquatic ecosystem and is also a significant concern in closed aquaculture systems. The threat of ammonia has been increasing with rising anthropogenic activities including intensified aquaculture. In this study, we aimed to investigate ammonia toxicity and metabolism mechanisms in the hepatopancreas, a major organ for Vitellogenin (Vtg) synthesis and defending against ammonia stress, of female swimming crab Portunus trituberculatus which is an important fishery and aquaculture species, by integrating physiological, transcriptome and metabolome analyses. The results revealed that ammonia exposure (10 mg/L, an environmentally relevant concentration) resulted in a remarkable reduction in vtg expression and depression of multiple signaling pathways for reproductive regulators including methyl farnesoate, ecdysone and neuroparsin, demonstrating for the first time that ammonia impairs swimming crab female reproduction. In addition, a number of important genes and metabolites in glycolysis, the Krebs cycle, fatty acid β-oxidation and synthesis were significantly downregulated, indicating that changes in ammonia levels lead to a general depression of energy metabolism in hepatopancreas. After ammonia exposure, an increased level of urea and a reduction of amino acid catabolism were observed in hepatopancreas, suggesting that urea cycle was utilized to biotransform ammonia, and amino acid catabolism was decreased to reduce endogenous ammonia generation. Furthermore, antioxidant systems were altered following ammonia exposure, which was accompanied by proteins and lipid oxidations, as well as cellular apoptosis. These results indicate that ammonia leads to metabolic suppression, oxidative stress and apoptosis in P. trituberculatus hepatopancreas. The findings improve the understanding for the mechanisms of ammonia toxicity and metabolism in P. trituberculatus, and provide valuable information for assessing potential ecological risk of environmental ammonia and improving aquaculture management.

Ovarian fullness affects biochemical composition and nutritional quality of female swimming crab Portunus trituberculatus

Ovary is an important edible component of female crabs in many countries, and ovarian fullness (maturity) had become an important quality indicator used for crab marketing. Adult females Portunus trituberculatus are typically divided into four grades (Grade I - Ⅳ) based on ovarian fullness in the carapace during the marketing. This study investigated the chemical composition and nutritional quality of market size female P. trituberculatus. The gonadosomatic index (GSI), hepatosomatic index (HSI) and total edible yield (TEY) showed a stepwise increase from Grade Ⅰ to Ⅳ (P < 0.05). Crude protein and total lipid content in both ovaries and muscle significantly increased with fullness, where Grade Ⅱ - Ⅳ had significantly higher lipid contents in the hepatopancreas compared to Grade Ⅰ. Redness (a*) of carapace and ovaries was consistent with the total carotenoid contents in tissues. Σ MUFA in both ovaries and muscle increased with crab grade, while Σ PUFA in ovaries and muscle, as well as Σ MUFA in the hepatopancreas decreased. For most amino acids in ovaries and muscle were also found to increase with grade. Higher-graded females generally had higher TEY, color parameters and better nutritional quality in edible tissues than the Grade I and II, which appears related to their different ovary stages of P. trituberculatus.

Ovarian development and nutritional quality changes of the wild-caughtPortunus trituberculatusduring the artificial fattening period

A female swimming crab (Portunus trituberculatus) with fully developed ovaries is considered one of the most nutritious types of seafood. The fishing yield of P. trituberculatus in China has always been high; however, its economic value has been low and unreliable due to poor ovarian development and low nutritional value. Artificial fattening is an effective way to improve the value of wild-caught crabs, and this study focused on analysing the ovarian development and nutritional quality of the female P. trituberculatus during an artificial fattening period. Therefore, this study provides scientific evidence on the effects of artificial fattening on female P. trituberculatus and can guide the development of nutritional quality regulations for wild-caught female crabs during the fattening process. The results showed that the ovaries of the wild female P. trituberculatus developed gradually. The ovarian morphology became bulkier, while the gonadosomatic index (GSI) and total edible yield (TEY) were significantly improved after artificial fattening. Significant changes in the nutritional components of the edible tissues were observed, and the moisture content in the ovaries and hepatopancreas decreased continually, while both the protein and fat content in the ovaries significantly increased. Moreover, the fat content in the hepatopancreas significantly increased. The saturated fatty acids(ΣSFA) in the ovaries and hepatopancreas had an increasing trend after fattening, while ΣPUFA and Σn-3PUFA first decreased and then increased. In contrast, the ratio of Σn-3PUFA to Σn-6PUFA decreased steadily. However, the fatty acid composition of the muscles did not change significantly. The levels of all the amino acids increased continuously during the fattening process, and EAA increased significantly in the early stages of the fattening period. Consequently, all amino acids became nonlimiting amino acids after fattening. Furthermore, the ratio of EAA/NEAA in the ovaries increased continually until the end of the fattening period. On the other hand, the fatness and TEY increased significantly after artificial fattening. In addition, the nutritional value significantly improved with the exception of the high-quality fatty acids in the ovaries and hepatopancreas, which were slightly lower in both.

Effect of exogenous estrogen on the ovarian development and gene expression in the female swimming crab Portunus trituberculatus (Miers, 1876) (Decapoda: Brachyura: Portunidae)

Effect of exogenous estrogen on the ovarian development and gene expression in the female swimming crab Portunus trituberculatus (Miers, 1876) (Decapoda: Brachyura: Portunidae)

De novo transcriptome sequencing and analysis of male and female swimming crab (Portunus trituberculatus) reproductive systems during mating embrace (stage II)

BackgroundThe swimming crab Portunus trituberculatus is one of the most commonly farmed crustaceans in China. As one of the most widely known and high-value edible crabs, it crab supports large crab fishery and aquaculture in China. Only large and sexually mature crabs can provide the greatest economic benefits, suggesting the considerable effect of reproductive system development on fishery. Studies are rarely conducted on the molecular regulatory mechanism underlying the development of the reproductive system during the mating embrace stage in this species. In this study, we used high-throughput sequencing to sequence all transcriptomes of the P. trituberculatus reproductive system.ResultsTranscriptome sequencing of the reproductive system produced 81,688,878 raw reads (38,801,152 and 42,887,726 reads from female and male crabs, respectively). Low-quality (quality <20) reads were trimmed and removed, leaving only high-quality reads (37,020,664 and 41,021,030 from female and male crabs, respectively). A total of 126,188 (female) and 164,616 (male) transcripts were then generated by de novo transcriptome assembly using Trinity. Functional annotation of the obtained unigenes revealed that a large number of key genes and some important pathways may participate in cell proliferation and signal transduction. On the basis of our transcriptome analyses and as confirmed by quantitative real-time PCR, a number of genes potentially involved in the regulation of gonadal development and reproduction of P. trituberculatus were identified: ADRA1B, BAP1, ARL3, and TRPA1.ConclusionThis study is the first to report on the whole reproductive system transcriptome information in stage II of P. trituberculatus gonadal development and provides rich resources for further studies to elucidate the molecular basis of the development of reproductive systems and reproduction in crabs. The current study can be used to further investigate functional genomics in this species.

Taste evaluations of ovigerous and soft-shelled female swimming crab &lt;i&gt;Portunus trituberculatus&lt;/i&gt; meat extracts

Taste evaluations of ovigerous and soft-shelled female swimming crab &lt;i&gt;Portunus trituberculatus&lt;/i&gt; meat extracts

Effect of estradiol on vitellogenesis and oocyte development of female swimming crab, Portunus trituberculatus

The vitellogenesis process of crustacean includes endogenous vitellogenic stage and exogenous vitellogeneic stage because the major vitellogenesis sites of two stages are localized in ovary and hepatopancreas, respectively. The present study was conducted to investigate the effects of different concentrations (0, 10−10, 10−9, 10−8, 10−7and 10−6mol/L) of exogenous estradiol (E2) on Vitellogenin (Vg)-mRNA expressions and Vg/Vitellin (Vn) levels in the ovaries and hepatopancreas for both endogenous and exogenous vitellogenic stage via in vitro experiment, and the oocyte diameters were further measured for the female swimming crab (Portunus trituberculatus). During endogenous vitellogenic stage, the Vg-mRNA expression level, Vn contents and the oocyte diameters of endogenous vitellogenic ovaries were significantly promoted in low concentration of E2 treatment (10−9mol/L and 10−8mol/L). However, the Vg-mRNA level in hepatopancreas was not enhanced by increasing concentrations of exogenous E2 and the hepatopancreatic Vg/Vn level was not detectable in this stage. During exogenous vitellogenic stage, only high-concentration of E2 treatment (10−6mol/L) could significantly improve the Vg-mRNA expression levels in ovary, while exogenous E2 had no significant effect on Vn contents and oocyte diameters. Moreover, the higher Vg-mRNA expression and Vg/Vn level in the hepatopancreas were detected in the high-concentration E2 treatment (10−7mol/ L-10−6mol/L). In conclusion, all results together indicated that exogenous E2 had a significant effect on vitellogenesis in ovaries at endogenous vitellogenic stage and in hepatopancreas at exogenous vitellogenic stage, but the effects of E2 were dose dependent and stage-specific.

Cloning, tissue expression of the fatty acid-binding protein (Pt-FABP1) gene, and effects of dietary phospholipid levels on fabp and vitellogenin gene expression in the female swimming crab Portunus trituberculatus

In the present study, the cDNA of fatty acid-binding protein (Pt-FABP1) from the hepatopancreas of swimming crab (Portunus trituberculatus) was cloned by rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of Pt-fabp1 was 730bp and encoded a 130 amino acids polypeptide that was highly homologous to related genes from other crustacean. Quantitative PCR analysis revealed that Pt-fabp1 expression was detected in various tissues, and the highest expression levels was occurred in the hepatopancreas. The Pt-fabp1 expression levels in the ovary would depend on the stages of ovarian development, and the expression of Pt-fabp1 reached the maximum at the stage IV. The effects of dietary soybean lecithin (SL) on the Pt-fabp1 and vitellogenin (VTG) expression, and steroid hormones levels were investigated. After 16weeks of feeding, the results showed that the expression level of Pt-fabp1 in hepatopancreas and the content of progesterone (PG) in hemolymph did significantly increase with dietary SL supplementation up to 2% (P<0.05). Swimming crab fed the diet containing 4% SL had higher hepatopancreas vtg gene expression and the content of 17 β-estradiol (E2) in hemolymph than those fed the control diet (P<0.05). This study suggested that Pt-FABP may have a positive function in ovary maturation of female swimming crab. Meanwhile, these results not only demonstrated that the gene expression of Pt-fabp1 and vtg in hepatopancreas can be modulated by dietary SL levels, but also clearly supported the hypothesis that the positive effects of dietary SL on the ovarian development of female swimming crab.

Effects of starvation and feeding on blood chemistry, fatty acid composition and expression of vitellogenin and fatty acid-binding protein genes in female swimming crab Portunus trituberculatus broodstock

Portunus trituberculatus broodstock were stocked in plastic tanks to evaluate the effects of starvation and feeding on gonadal development, blood chemistry, fatty acid composition, and expression of vitellogenin (Vtg) and fatty acid-binding protein genes (FABP) in females. Two treatments (starved and fed) were randomly assigned to triplicate groups of 90 swimming crab broodstock (approximately 230 ± 45 g). In the starved treatment, crabs were starved for 30 days, whereas in the fed treatment crabs were fed once a day with clams. The gonadosomatic index decreased significantly in starved crabs (P 0.05). Starvation suppressed gonadal development in female swimming crab broodstock.

Current fishing practices may induce low risk of sperm limitation in female swimming crab Portunus trituberculatus in the East China Sea

Potential sperm limitation of the swimming crab Portunus trituberculatus was exam- ined during the reproductive season from September 2006 to April 2007 in the East China Sea. We documented developmental variations between the spermatheca and ovary and distinguished these into 5 stages. We counted the number of stored sperm in paired spermathecae and found that more than 50% of sperm initially received during mating disappeared as the sperm plug degenerated; around 1.70 × 10 8 were used for final fertilization, and there was significant correla- tion between the final number of stored sperm and female carapace width. Lastly, using knowl- edge of the reproductive characteristics of P. trituberculatus, we calculated potential sperm:egg ratios of 221:1 or 153:1 for the first brood, and 55:1 or 38:1 for lifetime broods—either from the per- spective of a fishery resource assessment or from the perspective of seed production. From com- parison to sperm:egg ratios of Callinectes sapidus (for lifetime broods this ranges from 10:1 to 42:1), we can infer that female P. trituberculatus in the East China Sea may be at low risk of sperm limitation under current fishing practices. This may be the result of greater fishing mortality of females, causing an increase in the operational sex ratio. The present study improves our knowl- edge of sperm limitation in brachyurans as fishing management in China is non-selective, which differs from other exploited decapod crustacean species around the world.

Reproductive performance and offspring quality of the first and the second brood of female swimming crab, Portunus trituberculatus

Although the swimming crab Portunus trituberculatus females can spawn up to 5 times during a reproductive season, only larvae hatched from the first brood are normally used for larval culture in commercial hatcheries. With the increasing price of swimming crab broodstock and decreasing availability of wild stock, there are increasing interests in the possible utilization of the second brood for larval culture. However, to date, no detailed study has been conducted to assess the reproductive performance and offspring quality from the second brood of female P. trituberculatus. The present study was conducted to compare reproductive performance and offspring quality of the first (1st) and the second brood (2nd) produced by female P. trituberculatus during a reproductive season. No significant differences in several important reproductive parameters, including percentage of females spawned, percentage of berried females successfully hatched, egg production per female and fecundity per unit body weight, was found between the first and the second brood. However, the first brood had significantly higher individual egg wet weight (1st = 40.54 µg; 2nd = 31.40 µg), egg dry weight (1st = 13.51 µg; 2nd = 10.55 µg) and hatchability (1st = 78.41%; 2nd = 66.04%), and significantly higher survival (1st = 88.31%; 2nd = 65.38%) and faster development (1st = 3.82 days; 2nd = 4.34 days) from zoea I to zoea II and showed better starvation resistance in newly hatched larvae (1st = 5.03 days; 2nd = 2.98 days) than the second brood ( P < 0.05). Furthermore, the newly hatched zoea I from the first brood also had significantly higher total lipids, 16:1 n− 7, 18:1 n− 9, threonine (Thr) and arginine (Arg) contents, but lower levels of 18:0 and histidine (His) ( P < 0.05) as compared to those of the second brood. These biochemical differences are likely linked to different larval quality of the first and the second brood.

Annual reproductive cycle of the female swimming crab, Portunus trituberculatus off the coast of Shimizu city, Shizuoka, prefecture, Japan

Annual reproductive cycle of the female swimming crab, Portunus trituberculatus off the coast of Shimizu city, Shizuoka, prefecture, Japan

Folk classification of the crabs and swimming crabs (Crustacea – Brachyura) of the Mamanguape river estuary, Northeastern – Brazil

BackgroundFolk taxonomy is a sub-area of ethnobiology that study the way of how traditional communities classify, identify and name their natural resources. The work present was undertaken in two traditional communities (Barra de Mamanguape and Tramataia). The objective of this study was investigate the ethnobiological classification of the local crabs and swimming crabs used by the crustaceous gatherers of the Mamanguape River Estuary (MRE), Paraíba State, Brazil.MethodsThe methodology used here involved a combination of qualitative methods (open interviews, semi-structured interviews, direct observations, guided tours, surveys, and interviews in synchronic and diachronic situations that crossed-checked and repeated identifications) and quantitative methods (Venn diagram). A total of 32 men and women were interviewed in the two communities. Specimens of the local crustaceans were collected and identified by the harvesters themselves, subsequently fixed in formalin, conserved in 70% ethyl alcohol, identified using appropriate specialized literature, and then deposited in the laboratory of the Zoology Department of the University State of Paraiba.ResultsThe crustaceous gatherers we studied were observed to group crustaceans according to their similarities and differences, producing a hierarchical classification system containing four levels of decreasing taxonomic order: unique beginner, life-form, generic, and specific. A sequential and/or semantic system classification system that is used to classify the ontogeny of the female swimming crab was also identified.Of the nine folk generics identified, 44.5% were monotypic. 55.5% were polytypic and were subdivided into 15 folk specifics.An identification key was elaborated with the data obtained about the folk polytypics generics.ConclusionThe detailed knowledge concerning the crabs and swimming crabs revealed by the MRE crustaceous gatherers demonstrates that these people detain a vast knowledge concerning these marine resources. This local knowledge provides a rich but little-known source of information that will aid future ecological and/or zoological studies in the region that will be indispensable for producing management plans to help guarantee the sustainability of these local natural resources.

Estimation of mortality rates of female swimming crab Portunus tribuberculatus Meirs from single-release marking studies.

This paper describes a field study to estimate instantaneous fishing and natural mortality rates of swimming crab from mark recoveries, denoted by F and M, respectively. Efforts are made to eliminate systematic errors which influence estimates. Paint marks on the carapace of mated or egg holding female crab are assured to be retained for a research period from May through July. The observation is censored at 60 days after release. The goodness of fit of the theoretical model to the recovery data is considered and estimates of F and M are obtained. It is concluded that natural mortality of the crab is small and fishing mortality is large in Hiuchi-Nada area.