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Fulltext Female-specific SNP markers provide insights into a WZ/ZZ sex determination system for mud crabs Scylla paramamosain, S. tranquebarica and S. serrata with a rapid method for genetic sex identification

Shi X, Waiho K, Li X, Ikhwanuddin M, Miao G, Lin F, et al.

BMC Genomics, 2018 Dec 29;19(1):981.
PMID: 30594128 DOI: 10.1186/s12864-018-5380-8

BACKGROUND: Mud crabs, Scylla spp., are commercially important large-size marine crustaceans in the Indo-West Pacific region. As females have the higher growth rate and economic value, the production of all female stocks is extremely essential in aquaculture. However, the sex determination mechanism is still unclear. Development of sex-specific genetic markers based on next-generation sequencing proved to be an effective tool for discovering sex determination system in various animals.
RESULTS: Restriction-site associated DNA sequencing (RAD-seq) was employed to isolate sex-specific SNP markers for S. paramamosain. A total of 335.6 million raw reads were obtained from 20 individuals, of which 204.7 million were from 10 females and 130.9 million from 10 males. After sequence assembly and female-male comparison, 20 SNP markers were identified to be sex-specific. Furthermore, ten SNPs in a short sequence (285 bp) were confirmed heterozygous in females and homozygous in males in a large population by PCR amplification and sequencing. Subsequently, a female-specific primer was successfully designed according to the female-specific nucleotide which could amplify an expected band from females but not from males. Thus, a rapid and effective method for molecular sexing in S. paramamosain was developed, meanwhile, this method could successfully identify the sex of S. tranquebarica and S. serrata. Finally, nine and four female-specific SNP markers were detected in S. tranquebarica and S. serrata, respectively.
CONCLUSIONS: Sex-specific SNP markers were firstly identified in crab species and showed female heterogamety and male homogamety, which provided strong genetic evidence for a WZ/ZZ sex determination system in mud crabs S. paramamosain, S. tranquebarica and S. serrata. These findings will lay a solid foundation for the study of sex determination mechanism, sex chromosome evolution, and the development of mono-sex population in crustaceans.

Matched MeSH terms: Brachyura/genetics*
Fulltext Transcriptome Analysis and Differential Gene Expression on the Testis of Orange Mud Crab, Scylla olivacea, during Sexual Maturation

Waiho K, Fazhan H, Shahreza MS, Moh JH, Noorbaiduri S, Wong LL, et al.

PLoS One, 2017;12(1):e0171095.
PMID: 28135340 DOI: 10.1371/journal.pone.0171095

Adequate genetic information is essential for sustainable crustacean fisheries and aquaculture management. The commercially important orange mud crab, Scylla olivacea, is prevalent in Southeast Asia region and is highly sought after. Although it is a suitable aquaculture candidate, full domestication of this species is hampered by the lack of knowledge about the sexual maturation process and the molecular mechanisms behind it, especially in males. To date, data on its whole genome is yet to be reported for S. olivacea. The available transcriptome data published previously on this species focus primarily on females and the role of central nervous system in reproductive development. De novo transcriptome sequencing for the testes of S. olivacea from immature, maturing and mature stages were performed. A total of approximately 144 million high-quality reads were generated and de novo assembled into 160,569 transcripts with a total length of 142.2 Mb. Approximately 15-23% of the total assembled transcripts were annotated when compared to public protein sequence databases (i.e. UniProt database, Interpro database, Pfam database and Drosophila melanogaster protein database), and GO-categorised with GO Ontology terms. A total of 156,181 high-quality Single-Nucleotide Polymorphisms (SNPs) were mined from the transcriptome data of present study. Transcriptome comparison among the testes of different maturation stages revealed one gene (beta crystallin like gene) with the most significant differential expression-up-regulated in immature stage and down-regulated in maturing and mature stages. This was further validated by qRT-PCR. In conclusion, a comprehensive transcriptome of the testis of orange mud crabs from different maturation stages were obtained. This report provides an invaluable resource for enhancing our understanding of this species' genome structure and biology, as expressed and controlled by their gonads.

Matched MeSH terms: Brachyura/genetics*; Brachyura/physiology*
Green-synthesized CdS nano-pesticides: Toxicity on young instars of malaria vectors and impact on enzymatic activities of the non-target mud crab Scylla serrata

Sujitha V, Murugan K, Dinesh D, Pandiyan A, Aruliah R, Hwang JS, et al.

Aquat Toxicol, 2017 Jul;188:100-108.
PMID: 28482328 DOI: 10.1016/j.aquatox.2017.04.015

Currently, nano-formulated mosquito larvicides have been widely proposed to control young instars of malaria vector populations. However, the fate of nanoparticles in the aquatic environment is scarcely known, with special reference to the impact of nanoparticles on enzymatic activity of non-target aquatic invertebrates. In this study, we synthesized CdS nanoparticles using a green protocol relying on the cheap extract of Valoniopsis pachynema algae. CdS nanoparticles showed high toxicity on young instars of the malaria vectors Anopheles stephensi and A. sundaicus. The antimalarial activity of the nano-synthesized product against chloroquine-resistant (CQ-r) Plasmodium falciparum parasites was investigated. From a non-target perspective, we focused on the impact of this novel nano-pesticide on antioxidant enzymes acetylcholinesterase (AChE) and glutathione S-transferase (GST) activities of the mud crab Scylla serrata. The characterization of nanomaterials was carried out by UV-vis and FTIR spectroscopy, as well as SEM and XRD analyses. In mosquitocidal assays, LC50 of V. pachynema-synthesized CdS nanoparticles on A. stephensi ranged from 16.856 (larva I), to 30.301μg/ml (pupa), while for An. sundaicus they ranged from 13.584 to 22.496μg/ml. The antiplasmodial activity of V. pachynema extract and CdS nanoparticles was evaluated against CQ-r and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. IC50 of V. pachynema extract was 58.1μg/ml (CQ-s) and 71.46μg/ml (CQ-r), while nano-CdS IC50 was 76.14μg/ml (CQ-s) and 89.21μg/ml (CQ-r). In enzymatic assays, S. serrata crabs were exposed to sub-lethal concentrations, i.e. 4, 6 and 8μg/ml of CdS nanoparticles, assessing changes in GST and AChE activity after 16days. We observed significantly higher activity of GST, if compared to the control, during the whole experiment period. In addition, a single treatment with CdS nanoparticles led to a significant decrease in AChE activity over time. The toxicity of CdS nanoparticles and Cd ions in aqueous solution was also assessed in mud crabs, showing higher toxicity of aqueous Cd ions if compared to nano-CdS. Overall, our results underlined the efficacy of green-synthesized CdS nanoparticles in malaria vector control, outlining also significant impacts on the enzymatic activity of non-target aquatic organisms, with special reference to mud crabs.

Matched MeSH terms: Brachyura/drug effects*; Brachyura/enzymology
Fulltext A review of maturation diets for mud crab genus Scylla broodstock: Present research, problems and future perspective

Azra MN, Ikhwanuddin M

Saudi J Biol Sci, 2016 Mar;23(2):257-67.
PMID: 26981008 DOI: 10.1016/j.sjbs.2015.03.011

Study of broodstock maturation diets is important in order to increase the quality of berried females, which indirectly improve the larval quantity in the hatchery production of cultured species. This paper reviewed the studies on the maturation diets for mud crab broodstock, genus Scylla and compared independently to identify their effect on reproductive performance and larval quality. The broodstock is usually caught from the wild and held in the spawning or maturation tank for further use of hatchery seed production. Mud crab broodstock was fed either natural diet, artificial diet or mixed diet. Trash fishes were commonly used as a natural feed for mud crab broodstock; meanwhile artificial diets are from formulated fish meal and various kinds of feed. The results indicated that mud crab broodstock has a high dietary requirement for lipids, fatty acids and protein which are to be used during the maturation and breeding processes. However, the natural diet produce better larval quality compared to the artificial diet. The mixed diet is the better diet which resulted in better reproductive performances such as growth, survival, fecundity and maturation processes. This review also discusses the problems in the previous studies for the potential future research to develop very high quality and cost-effective formulated diet for the enhancement of broodstock and seed production technology. Information from this review can be useful in developing a better quality of crustacean broodstock's diet for commercial hatchery production.

Matched MeSH terms: Brachyura
Fulltext Chitosan extracted from mud crab (Scylla olivicea) shells: physicochemical and antioxidant properties

Sarbon NM, Sandanamsamy S, Kamaruzaman SF, Ahmad F

J Food Sci Technol, 2015 Jul;52(7):4266-75.
PMID: 26139891 DOI: 10.1007/s13197-014-1522-4

The aim of this study is to report the yield of extraction, as well as the physicochemical and antioxidant properties of extracted chitosan from mud crabs (S.olivacea) as compared to commercial chitosan. The yield obtained for extracted chitosan was 44.57 ± 3.44 % with a moisture and ash content of 9.48 ± 0.59 % and 5.97 ± 0.90 %, respectively. Commercial chitosan demonstrated a higher degree of deacetylation (58.42 ± 2.67 %), water (250 ± 9.90 %) and fat (329 ± 7.07 %) binding capacity, solubility (73.85 %), viscosity (463.25 ± 13.10 %) and also the whiteness value (77.8 ± 0.47) compared to the extracted chitosan, which were only 53.42 ± 0.88 %, 180 ± 0.00 %, 260 ± 0.00 %, 53.38 %, 383.9 ± 28.43 % and 62.1 ± 7.52 %, respectively. The structure of extracted and commercial chitosan was also investigated using Fourier Transform Infrared Spectroscopy (FTIR). In conclusion, the extracted chitosan possessed potential properties similar to the commercial chitosan with high reducing power but low in the scavenging activity on the DPPH and hydroxyl radicals compared to the commercial chitosan.

Matched MeSH terms: Brachyura
Fulltext Data on population density, growth, survival, water quality, larval stage index and ingestion rate of selected microalgae of portunids crabs at different feeding regimes

Syafaat MN, Muhammad T, Abol-Munafi AB, Ikhwanuddin M

Data Brief, 2019 Oct;26:104438.
PMID: 31528675 DOI: 10.1016/j.dib.2019.104438

Population density, growth, survival, water quality and larval stage index of purple mud crab, Scylla tranquebarica at different feeding regimes and the data on ingestion rate of chosen microalgae, survival and larval development of blue swimming crab, Portunus pelagicus are presented. A twenty days of S. tranquebarica larval culture from zoeal 1 until megalopa stage under two different feeding regimes of A) Rotifer, Artemia nauplii and shrimp meat and B) Rotifer, Artemia nauplii and artificial feed is shared. A method on investigation of individual larvae of P. pelagicus capability to catch four different types of microalgae within 24 h is also shared. Direct eye observation, data collected through the larval rearing culture of S. tranquebarica and further statistical analysis were done daily until the crabs reached the megalopa stage. The result obtained from the optimum density of selected microalgae fed by individual larvae of P. pelagicus will be combined with the highest survival rate and larval stage index to develop feeding schedule for crab larvae P. pelagicus. This dataset has not previously been published and is of great potential for further comparison with other - and future investigation of various feeding regimes affected the crab culture. The collected information could be used as a standard feeding regime for nursery and hatchery seed production of others portunids crabs. The data described in this article are available as a supplementary file to this article.

Matched MeSH terms: Brachyura
Fulltext Improving Survival of Juvenile Scalloped Spiny Lobster (Panulirus homarus) and Crucifix Crab (Charybdis feriatus) Using Shelter and Live Prey

Ma CH, Huang PY, Chang YC, Pan YJ, Azra MN, Chen LL, et al.

Animals (Basel), 2021 Feb 02;11(2).
PMID: 33540637 DOI: 10.3390/ani11020370

Cannibalism is a major problem in lobster and crab aquaculture. Reducing the aggressive characteristics of lobsters and crabs can improve survival during the culturing process. In this study, juvenile scalloped spiny lobsters (Panulirus homarus) and crucifix crabs (Charybdis feriatus) were both cultured under different shelter and live prey conditions. Groups with shelter (seaweed and cotton filter) showed a better survival rate than the control group (no shelter; p < 0.05) for both Pa. homarus and Char. feriatus. Co-culturing with live prey (Litopenaeus vannamei) significantly benefited the juveniles of Pa. homarus and visibly increased the survival of juvenile Char. feriatus. Although providing shelter is currently the main method for reducing agonistic behavior, it must be continually altered as the lobsters and crabs grow. Live prey can grow and attract lobsters and crabs to hunt them, and live prey can be supplemented at any time. They can also be used as an additional source of income during the harvest season.

Matched MeSH terms: Brachyura
Fulltext High-Density Genetic Linkage Maps Provide Novel Insights Into ZW/ZZ Sex Determination System and Growth Performance in Mud Crab (Scylla paramamosain)

Waiho K, Shi X, Fazhan H, Li S, Zhang Y, Zheng H, et al.

Front Genet, 2019;10:298.
PMID: 31024620 DOI: 10.3389/fgene.2019.00298

Mud crab, Scylla paramamosain is one of the most important crustacean species in global aquaculture. To determine the genetic basis of sex and growth-related traits in S. paramamosain, a high-density genetic linkage map with 16,701 single nucleotide polymorphisms (SNPs) was constructed using SLAF-seq and a full-sib family. The consensus map has 49 linkage groups, spanning 5,996.66 cM with an average marker-interval of 0.81 cM. A total of 516 SNP markers, including 8 female-specific SNPs segregated in two quantitative trait loci (QTLs) for phenotypic sex were located on LG32. The presence of female-specific SNP markers only on female linkage map, their segregation patterns and lower female: male recombination rate strongly suggest the conformation of a ZW/ZZ sex determination system in S. paramamosain. The QTLs of most (90%) growth-related traits were found within a small interval (25.18-33.74 cM) on LG46, highlighting the potential involvement of LG46 in growth. Four markers on LG46 were significantly associated with 10-16 growth-related traits. BW was only associated with marker 3846. Based on the annotation of transcriptome data, 11 and 2 candidate genes were identified within the QTL regions of sex and growth-related traits, respectively. The newly constructed high-density genetic linkage map with sex-specific SNPs, and the identified QTLs of sex- and growth-related traits serve as a valuable genetic resource and solid foundation for marker-assisted selection and genetic improvement of crustaceans.

Matched MeSH terms: Brachyura
Fulltext Sexual dimorphism in mud crabs: a tale of three sympatric Scylla species

Fazhan H, Waiho K, Fujaya Y, Rukminasari N, Ma H, Ikhwanuddin M

PeerJ, 2021;9:e10936.
PMID: 33954025 DOI: 10.7717/peerj.10936

Sexual dimorphism is a common phenomenon in the animal kingdom. To test the consistency of sexual dimorphism patterns among sympatric species of the same genus, ten morphometric characteristics of mud crabs Scylla olivacea, S. tranquebarica and S. paramamosain were measured and compared using Discriminant Function Analysis (DFA). The descriptive analysis revealed that in all three species, body size dimensions and cheliped dimensions were significantly larger in males whereas the abdomen width was female-biased. Also, we described a morphological variation (carapace width, CW ≤ CW at spine 8, 8CW) that is unique to S. olivacea. Discriminant function analysis revealed that all nine morphometric characteristics were sexually dimorphic in S. olivacea, S. tranquebarica (except right cheliped's merus length, ML) and S. paramamosain (except 8CW). The obtained discriminant functions based on the morphometric ratios (with CW as divisor) correctly classified 100% of adults of known sex of all three species. Further, based on the selected body traits, DFA was able to almost completely distinguish males (94%), but not females (74%), among the three Scylla species. This study highlights that congeneric species of portunids (e.g., Scylla spp.) show similar sexually dimorphic characteristics (body size and secondary sexual characteristics).

Matched MeSH terms: Brachyura
Seasonal variation of total mercury transfer through a tropical mangrove food web, Setiu Wetlands

Siau YF, Le DQ, Suratman S, Jaaman SA, Tanaka K, Kotaro S

Mar Pollut Bull, 2021 Jan;162:111878.
PMID: 33341077 DOI: 10.1016/j.marpolbul.2020.111878

Seasonal variations in total mercury concentrations [Hg] and trophic transfer through the food web were assessed using stable isotopic tracers for the Setiu Wetlands, Terengganu. The [Hg] measured in surface sediments and biota varied inversely between wet and dry seasons. Increased rainfall and water disturbance during the wet season are suggested as the main factors releasing Hg from surface sediments and enhancing the bioavailability of Hg to biota. The elevated Hg levels associated with the leaf stage suggested that litterfall and atmospheric deposition may be the main Hg inputs into mangrove food webs. The positive relationships between log [Hg] and δ15N provided evidence for Hg biomagnification, however low trophic magnification slopes in both seasons indicated that the ecological risk of Hg in the wetland would be negligible. The [Hg] in fish and commercial crabs were below the permitted limits for human consumption.

Matched MeSH terms: Brachyura
Gonadal microRNA Expression Profiles and Their Potential Role in Sex Differentiation and Gonadal Maturation of Mud Crab Scylla paramamosain

Waiho K, Fazhan H, Zhang Y, Zhang Y, Li S, Zheng H, et al.

Mar Biotechnol (NY), 2019 Jun;21(3):320-334.
PMID: 30835008 DOI: 10.1007/s10126-019-09882-1

Although the sexual dimorphism in terms of gonadal development and gametogenesis of mud crab has been described, the internal regulating mechanism and sex differentiation process remain unclear. A comparative gonadal miRNA transcriptomic study was conducted to identify miRNAs that are differentially expressed between testes and ovaries, and potentially uncover miRNAs that might be involved in sex differentiation and gonadal maturation mechanisms of mud crabs (Scylla paramamosain). A total of 10 known miRNAs and 130 novel miRNAs were identified, among which 54 were differentially expressed. Target gene prediction revealed a significant enrichment in 30 KEGG pathways, including some reproduction-related pathways, e.g. phosphatidylinositol signalling system and inositol phosphate metabolism pathways. Further analysis on six differentially expressed known miRNAs, six differentially expressed novel miRNAs and their reproduction-related putative target genes shows that both miRNAs and putative target genes showed stage-specific expression during gonadal maturation, suggesting their potential regulatory roles in sex differentiation and reproductive development. This study reveals the sex-biased miRNA profile and establishes a solid foundation for understanding the sex differentiation and gonadal maturation mechanisms of S. paramamosain.

Matched MeSH terms: Brachyura
Transcriptome-Guided Identification of Carbohydrate Active Enzymes (CAZy) from the Christmas Island Red Crab, Gecarcoidea natalis and a Vote for the Inclusion of Transcriptome-Derived Crustacean CAZys in Comparative Studies

Gan HM, Austin C, Linton S

Mar Biotechnol (NY), 2018 Oct;20(5):654-665.
PMID: 29995174 DOI: 10.1007/s10126-018-9836-2

The Christmas Island red crab, Gecarcoidea natalis, is an herbivorous land crab that consumes mostly fallen leaf litter. In order to subsist, G. natalis would need to have developed specialised digestive enzymes capable of supplying significant amounts of metabolisable sugars from this diet. To gain insights into the carbohydrate metabolism of G. natalis, a transcriptome assembly was performed, with a specific focus on identifying transcripts coding for carbohydrate active enzyme (CAZy) using in silico approaches. Transcriptome sequencing of the midgut gland identified 70 CAZy-coding transcripts with varying expression values. At least three newly discovered putative GH9 endo-β-1,4-glucanase ("classic cellulase") transcripts were highly expressed in the midgut gland in addition to the previously characterised GH9 and GH16 (β-1,3-glucanase) transcripts, and underscoring the utility of whole transcriptome in uncovering new CAZy-coding transcripts. A highly expressed transcript coding for GH5_10 previously missed by conventional screening of cellulase activity was inferred to be a novel endo-β-1,4-mannase in G. natalis with in silico support from homology modelling and amino acid alignment with other functionally validated GH5_10 proteins. Maximum likelihood tree reconstruction of the GH5_10 proteins demonstrates the phylogenetic affiliation of the G. natalis GH5_10 transcript to that of other decapods, supporting endogenous expression. Surprisingly, crustacean-derived GH5_10 transcripts were near absent in the current CAZy database and yet mining of the transcriptome shotgun assembly (TSA) recovered more than 100 crustacean GH5_10s in addition to several other biotechnological relevant CAZys, underscoring the unappreciated potential of the TSA database as a valuable resource for crustacean CAZys.

Matched MeSH terms: Brachyura
Fulltext Nutrient Contents of the Freshwater Crab, Isolapotamon bauense from Sarawak, Malaysia (Borneo)

Grinang J, Tyan PS, Tuen AA, Das I

Trop Life Sci Res, 2017 Jul;28(2):75-87.
PMID: 28890762 MyJurnal DOI: 10.21315/tlsr2017.28.2.6

Data on nutrient contents of freshwater crabs are important for ecological studies and species conservation assessments, especially when the species concerned is threatened among others by habitat destruction and uncontrolled resources utilisation. Indeed comprehensive biological information is required to reconcile the needs between sustainable resources utilisation and conservation of the species. This study documents the nutrient contents of a freshwater crab, Isolapotamon bauense which is listed as 'Vulnerable' in the IUCN Red List of Threatened Species and also being harvested by local community for dietary supplement. Results show that muscles of the freshwater crab contain a substantial amount of nutrients in particular water content (male = 79.31 ± 2.30 %, female = 77.63 ± 0.56 %), protein (male = 77.47 ± 6.11 %, female = 63.28 ± 3.62 %), magnesium (male = 51.48 ± 16.10 mg/g, female = 39.73 ± 6.99 mg/g) and calcium (male = 25.50 ± 6.98 mg/g, female = 39.73 ± 6.99 mg/g). Means of nutrient contents between male and female crabs are not significantly different. It is estimated that an individual of I. bauense with weight range of 56-139 g contained on average of 0.35 ± 0.15 g of protein. Our estimation also shows that the number of individuals of the freshwater crab required to meet the recommended daily protein intakes of the community concerned is in the range 35-96 individuals for children, 130-188 individuals for adolescents, 171-179 individuals for men and 149-159 individuals for women. The results imply that harvesting of wild I. bauense as a source of protein supplement naturally may not be practical because of its relatively low population abundance, and conservation of the species for its ecological roles may thus be preferred.

Matched MeSH terms: Brachyura
Fabrication of nano-mosquitocides using chitosan from crab shells: Impact on non-target organisms in the aquatic environment

Murugan K, Anitha J, Dinesh D, Suresh U, Rajaganesh R, Chandramohan B, et al.

Ecotoxicol Environ Saf, 2016 Oct;132:318-28.
PMID: 27344400 DOI: 10.1016/j.ecoenv.2016.06.021

Mosquitoes are arthropods of huge medical and veterinary relevance, since they vector pathogens and parasites of public health importance, including malaria, dengue and Zika virus. Currently, nanotechnology is considered a potential eco-friendly approach in mosquito control research. We proposed a novel method of biofabrication of silver nanoparticles (AgNP) using chitosan (Ch) from crab shells. Ch-AgNP nanocomposite was characterized by UV-vis spectroscopy, FTIR, SEM, EDX and XRD. Ch-AgNP were tested against larvae and pupae of the malaria vector Anopheles stephensi obtaining LC50 ranging from 3.18 ppm (I) to 6.54 ppm (pupae). The antibacterial properties of Ch-AgNP were proved against Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi, while no growth inhibition was reported in assays conducted on Proteus vulgaris. Concerning non-target effects, in standard laboratory considtions the predation efficiency of Danio rerio zebrafishes was 68.8% and 61.6% against I and II instar larvae of A. stephensi, respectively. In a Ch-AgNP-contaminated environment, fish predation was boosted to 89.5% and 77.3%, respectively. Quantitative analysis of antioxidant enzymes SOD, CAT and LPO from hepatopancreas of fresh water crabs Paratelphusa hydrodromous exposed for 16 days to a Ch-AgNP-contaminated aquatic environment were conducted. Notably, deleterious effects of Ch-AgNP contaminating aquatic enviroment on the non-target crab P. hydrodromous were observed, particularly when doses higher than 8-10ppm are tested. Overall, this research highlights the potential of Ch-AGNP for the development of newer control tools against young instar populations of malaria mosquitoes, also highlighting some risks concerned the employ of nanoparticles in aquatic environments.

Matched MeSH terms: Brachyura
Fulltext Characterization of major allergens of local mud crab (Scylla serrata)

Rosmilah Misnan, Nurul Izzah Abdul Rahman, Zailatul Hani Mohd Yadzir, Noormalin Abdullah, Mohd Faizal Bakhtiar, Shahnaz Murad

Scientific Research Journal, 2015;12(1):1-7.
MyJurnal

Crab meat is widely consumed in several countries around the world. However, when consumed, crab meat are frequent cause of allergic reactions throughout the world. Scylla serrata is among the most common mud crab in Malaysia. In a previous study two major allergens of mud crab at 36 and 41 kDa was identified. Thus, the aim of this study is to further identify these major allergens by a proteomic approach. Protein extract was prepared and resolved by 2-dimensional electrophoresis (2-DE). Immunoblotting was then performed using reactive sera from patients with crab allergy. Major allergenic spots were then excised from the 2-DE gel and analysed by mass spectrometry. The 2-DE profile of the extract revealed approximately >100 protein spots between pH of 4.00 to 8.00. Mass spectrometry analysis has identified the 36 and 41 kDa proteins as tropomyosin and arginine kinase, respectively. Our findings indicated that tropomyosin and arginine kinase play a major role in allergic reaction to mud crab meat among local patients with crab meat allergy, and should be included in diagnostics and therapeutic strategies of this allergy.

Matched MeSH terms: Brachyura
Fulltext Infestation of parasitic rhizocephalan barnacles Sacculina beauforti (Cirripedia, Rhizocephala) in edible mud crab, Scylla olivacea

Waiho K, Fazhan H, Glenner H, Ikhwanuddin M

PeerJ, 2017;5:e3419.
PMID: 28674645 DOI: 10.7717/peerj.3419

Screening of mud crab genus Scylla was conducted in four locations (Marudu Bay, Lundu, Taiping, Setiu) representing Malaysia. Scylla olivacea with abnormal primary and secondary sexual characters were prevalent (approximately 42.27% of the local screened S. olivacea population) in Marudu Bay, Sabah. A total of six different types of abnormalities were described. Crabs with type 1 and type 3 were immature males, type 2 and type 4 were mature males, type 5 were immature females and type 6 were mature females. The abdomen of all crabs with abnormalities were dented on both sides along the abdomen's middle line. Abnormal crabs showed significant variation in their size, weight, abdomen width and/or gonopod or pleopod length compared to normal individuals. The mean body weight of abnormal crabs (type 1-5) were higher than normal crabs with smaller body size, while females with type 6 abnormality were always heavier than the normal counterparts at any given size. Sacculinid's externa were observed in the abdomen of crabs with type 4 and type 6 abnormalities. The presence of embryos within the externa and subsequent molecular analysis of partial mitochondrial COI region confirmed the rhizocephalan parasite as Sacculina beauforti. Future in-depth descriptions of the life cycle and characteristics of S. beauforti are recommended as it involves a commercially important edible crab species and the effect on human health from the consumption of crabs is of crucial concern.

Matched MeSH terms: Brachyura
Fulltext Serological prevalance of leptospiral infection in captive Malayan porcupiness (Hystrix brachyura)

Siti-Nurdyana, A.K., Bahaman, A.R., Sharma, R.S.K., Azlan, C.M., Abdul Razak, M.F.A.

Jurnal Veterinar Malaysia, 2016;28(2):1-3.
MyJurnal

Leptospirosis is recognised as one of the leading zoonotic diseases and rodents have been implicated as one of the natural reservoirs of the disease. The Malayan porcupines (Hystrix brachyura) which are also a rodent could possibly be a carrier of leptospiral organisms. This study was conducted to determine the serological prevalence of leptospiral infection among captive Malayan porcupines and to disclose the possibility of porcupines as a reservoir for leptospiral infection. Fifty serum samples were obtained from the Malayan porcupines kept in captivity at the Wildlife Conservation Centre, Sungai Dusun, Malaysia. The microscopic agglutination test (MAT) was performed on the serum samples to detect the presence of agglutinating antibodies to a panel of 16 Leptospira serovars (Australis, Autumnalis, Ballum, Bataviae, Canicola, Celledoni, Djasiman, Hardjobovis, Hardjopratjino, Hebdomadis, Hurstbridge, Icterohaemorrhagiae, Javanica, Pomona, Pyrogenes and Sejroe). From the serological test, 18% (n=9/50) of the Malayan porcupines tested had leptospiral antibodies to serovars Javanica (8%), Hurstbridge (4%), Ballum (2%), Celledoni (2%) and Hardjoprajitno (2%). It is seen that this study disclosed a high prevalence of leptospiral infection in the Malayan porcupines tested and indicated that the Malayan porcupines could possibly be a source of leptospirosis to other animals including humans and that they might play an important role in the epidemiology of leptospiral infection in the country.

Matched MeSH terms: Brachyura
Dataset on body weight, carapace width increment and growth band count of mud crabs, Scylla olivacea

Ikhwanuddin M, Amin-Safwan A, Hasyima-Ismail N, Azra MN

Data Brief, 2019 Oct;26:104477.
PMID: 31667242 DOI: 10.1016/j.dib.2019.104477

The present paper contains two datasets; i) the growth band count (GBC) of mud crab, Scylla olivacea collected from Setiu Wetlands, Terengganu coastal water, East coast of Peninsular Malaysia and ii) the increment sizes of body weight (BW) and carapace width (CW) of immature S. olivace after molting. The datasets presented here were associated with the research articles entitled i) "Study on carapace width growth band counts relationship of orange mud crab, S. olivacea (Herbst, 1796) from Terengganu Coastal Waters, Malaysia" (Hasyima-Ismail et al. 2017) [1] and ii) "Relationship between the carapace width and body weight increments and the confirmation of Stage 1 ovary after the molting of immature orange mud crabs, S. olivacea (Herbst, 1796), in captivity" (Amin-Safwan et al. 2019-2020) [2], and provided here as raw data of Supplementary materials. Raw datasets for GBC in the wild were generated by examination of the thin cross sectioning process of the gastric mill of S. olivacea. The GBC were measured for each individual crab wherein band counts ranged from 1 to 3. The analysis provides evidence that the GBC of the crabs can be determined through both mesocardiac and zygocardiac ossicles. This data is of importance to researchers for estimation of stock assessment and improvement of fisheries management to further improve policy. For the BW-CW increment data, a total of 135 immature crabs were sampled from Setiu Wetlands, Terengganu, Malaysia, and were introduced to limb autotomy technique in order to induced molt. Crabs were reared until successful molting and immediately prior to hardened shell, before final measurement of body weight and carapace width determination. Recorded data was analyzed by calculating the increment sizes, along with correlation and regression analysis between body weight and carapace width of mud crabs.

Matched MeSH terms: Brachyura
Feeding ecology and food preferences of Carcinoscorpius rotundicauda collected from the Pahang nesting grounds

Akbar John B, Kamaruzzaman B, Jalal K, Zaleha K

Sains Malaysiana, 2012;41:855-861.

The first time report on the feeding ecology and food preference of mangrove horseshoe crab Carcinoscorpius rotundicauda (Latreille 1802) at their nesting grounds along the Pahang coast is given. Monthly sampling was carried out between March 2010 and February 2011 covering both monsoonal (March to October) and non-monsoonal (November to February) seasons. Major macrobenthic gut contents (bivalves, gastropods, crustaceans, polychaetes and miscellaneous food items including plant materials) were identified using microscopic examination. An electivity index (E1) was calculated for the frequent food items observed in the gut region of C. rotundicauda during monsoon and non-monsoon seasons. The EI was negative for crustaceans and positive for all the other food items including bivalves, gastropods, polychaetes and miscellaneous food items (which include insects, amphipods, Isopods, larval and juvenile stages of fishes, foraminifera and other Annelid worms). It is interesting to note that C. rotundicauda prefered less number of bivalves than polychaetes during non monsoon seasons but it was the reverse during monsoonal period. Male crabs intensely preyed on gastropods and female prefers polychaete worms during the peak mating/nesting season (June - August 2010). Seasonal variations in food composition showed that mollusks formed the main item especially gastropods. Unidentified organic matters in the gut content analysis of C. rotundicauda showed high preference towards plant materials. Gastro Somatic Index (GaSI) analysis showed that the feeding intensity of male crabs was higher during non-monsoon period while it was higher during monsoonal period in female crabs. In conclusion, the feeding ecology of mangrove horseshoe crabs were more similar to its closer and distant conspecifics. However, it was postulated that the higher preference of polychaete worms by the female C. rotundicauda during the peak mating season indicated its role in regulating the nesting behaviour.

Matched MeSH terms: Brachyura
Characterization of Aquimarina hainanensis isolated from diseased mud crab Scylla serrata larvae in a hatchery

Midorikawa Y, Shimizu T, Sanda T, Hamasaki K, Dan S, Lal MTBM, et al.

J Fish Dis, 2020 May;43(5):541-549.
PMID: 32147853 DOI: 10.1111/jfd.13151

Mass mortality due to necrosis signs occurred in hatchery-reared zoea stage larvae of the mud crab Scylla serrata in Okinawa, Japan, and a causative bacterium was isolated. In this study, we identified and characterized the bacterium by genome analysis, biochemical properties and pathogenicity. The bacterium was a Gram-negative, non-motile, long rod, forming yellow colonies on a marine agar plate. It grew at 20-33°C (not at 37°C) and degraded chitin and gelatin. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Aquimarina hainanensis. Genome sequence data obtained from Illumina MiSeq generated 29 contigs with 3.56 Mbp in total length and a G + C content of 32.5%. The predicted 16 chitinase genes, as putative virulence factors, had certain homologies with those of genus Aquimarina. Experimental infection with the bacterium conducted on larvae of four crustacean species, brine shrimp Artemia franciscana, freshwater shrimp Caridina multidentata, swimming crab Portunus trituberculatus and mud crab S. serrata, revealed that this bacterium was highly virulent to these species. The present study suggests that the bacterium caused mass mortality in mud crab seed production was A. hainanensis and can be widely pathogenic to crustaceans.

Matched MeSH terms: Brachyura

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