Examination of naturally infected felids and viverrids in Malaysia confirmed previously published records which indicated that P. westermani occurred only in felid cats. Felis planiceps and F. temnickli were reported as new host records. Analysis of stomach contents revealed no crab remains in either family of cats, but confirmed that felids were strictly carnivorous while viverrids were often omnivorous. In feeding experiments, only viverrids ate the host crabs Potomiscus johorensis and Parathelphusa maculata. The probable transmission of P. westermani to felids via paratenic hosts was discussed.
An ecologic study on Paragonimus in Malaysia was attempted from May to September 1967. Seven streams located in various directions and distances from Kuala Lumpur were surveyed for the study of intermediate hosts, snail and crab. One Malayan village and one aborigine village where infected crabs were found, and two tuberculosis hospitals in K.L. were surveyed for the study of human population. Intradermal tests along with sputum or stool examination to detect human infection by Paragonimus were employed. Wild animals, only a few, were shot in the vicinity of the aborigine village and several domestic cats from the Malayan village were bought. These animals were autopsied and examined for adult Paragonimus. Among five species of crab collected from the study areas, only two species, Potamon jahorenes and Parathelphusa maculata were found to be infected with Paragonimus. P. maculata seemed to be better crab host for the Paragonimus because this species had higher infection rate and metacercarial density than the other in the very same area. Three out of seven streams had infected crabs and the infection rate as well as the infection intensity varied from one stream to another. Only avilable snail in the streams was identified as Brotia costula. The infection rate of the snail was very low, six snails out of 11,898, which is about the same rate reported from other countries. Infected snail, however, had thousands of rediae uncountable containing about twelve microcercocercariae in each redia, sufficient enough to maintain the life cycle of the parasite even with only a few infected snail, the amplifier. This is the first confirmed report on the snail host of Paragonimus from Malaysia where the existence of Paragonimus had been reported in 1923. The first trial to study human population by means of intradermal test, sputum and/or stool examinations in Malaysia showed no evidence of human infection of Paragonimus. The number of animals, wild and domestic, examined for natural infection was too small to draw any statement. These examined animals were all negative for adult Paragonimus. Even though more extensive studies on wild animals and human population may be necessary for the definite conclusion, the facts that infected crabs from jungle stream where human contacts are extreamely rare, and also highly infected crabs from the area where none of humans or domestic animals were infected, strongly suggest the life cycle of Paragonimus in this area may be maintained by wild animal hosts rather than by human host. The morphology of all stages of the parasite, the pattern of penetrating glands, flame cells and excretroy bladder of cercaria, lancet shaped single cuticular spines and 6 branched ovary of adult worm obtained from experimentally infected cat, and the shape of egg including all measurements agree well with the characteristics of Paragonimus westermani.
Three species of tropical estuarine invertebrates were exposed to copper sulfate and cadmium chloride to investigate their potential as test specimens for sediment toxicity assays in the South-east Asian regions. The larvae of the reef sea urchin (Diadema setosum), the oyster (Crassostrea iradalei), and the mud crab (Scylla seratta Forskall) were used in the 48-hr assays with copper and cadmium as reference toxicants. In addition the sea urchin were tested for end point measurements at different stages of the larval development and a 60-min sperm bioassay. The study revealed that the sea urchin first cleavage, which is an assay end point and which takes place about 1 hr after fertilization, was the most sensitive stage for both toxicants, with copper being more toxic than cadmium. Sensitivity comparisons between the three invertebrate larvae revealed the mud crab zoea larvae to be most sensitive for cadmium with an LC50 value of 0.078 microgram/ml, while the sea urchin was more sensitive for copper, with EC50 values of 0.01 microgram/ml at the first cleavage stage and 0.04 microgram/ml at the pluteus larva stage. All the invertebrates tested gave responses that made them suitable test organisms for metal bioassays in the tropical estuarine environment.
The significance of food specific serum IgG4 antibody in food allergy is unclear and this led us to investigate the relevance of specific IgG4, along with IgG and IgE antibodies to two common food allergens in Malaysia. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum antibodies in 143 allergic rhinitis patients' sera, of which 47 were from patients with clinical indication of shrimp allergy, 46 with clinical indication of crab allergy and 50 without indication to either allergy. Clinical indication of allergy was based on answers to a questionnaire or results of the skin prick test. We found that the elevation of specific IgE or IgG4 is associated with shrimp and crab allergies but elevation of specific IgG is not associated with either allergy. However, the clinical utility of elevated specific IgG and IgG4 levels is pending further investigation.
Study site: Allergic rhinitis clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
A recent rise in crab aquaculture activities has intensified the generation of waste shells. In the present study, the waste shells were utilized as a source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shell is calcium carbonate which transformed into calcium oxide when activated above 700 degrees C for 2 h. Parametric studies have been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 5 wt.%; reaction temperature, 65 degrees C; and a stirring rate of 500 rpm. The waste catalyst performs equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to 11 times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity.
Aquaculture activity has increased the population of crab, hence increasing the generation of related wastes, particularly the shell. In addition, the number of molting process in crabs compounds further the amount of waste shell generated. As such, in the present work, the application of the waste crab shell as a source of CaO in transesterification of palm olein to biodiesel (methyl ester) was investigated. Preliminary XRD results revealed that thermally activated crab shell contains mainly CaO. Parametric study has been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 4 wt. %; and reaction temperature, 338 K. As compared to laboratory CaO, the catalyst from waste crab shell performs well, thus creating another low-cost catalyst source for producing biodiesel as well as adding value to the waste crab shell. Reusability of crab shell CaO has also been studied and the outcome confirmed that the catalyst is capable to be reutilized up to 11 times, without any major deterioration.
The prophenoloxidase activating system is an important innate immune response against microbial infections in invertebrates. The major enzyme, phenoloxidase, is synthesized as an inactive precursor and its activation to an active enzyme is mediated by a cascade of clip domain serine proteinases. In this study, a cDNA encoding a prophenoloxidase activating enzyme-III from the giant freshwater prawn Macrobrachium rosenbergii, designated as MrProAE-III, was identified and characterized. The full-length cDNA contains an open reading frame of 1110 base pair (bp) encoding a predicted protein of 370 amino acids including an 22 amino acid signal peptide. The MrProAE-III protein exhibits a characteristic sequence structure of a long serine proteases-trypsin domain and an N- and C-terminal serine proteases-trypsin family histidine active sites, respectively, which together are the characteristics of the clip-serin proteases. Sequence analysis showed that MrProAE-III exhibited the highest amino acid sequence similarity (63%) to a ProAE-III from Atlantic blue crab, Callinectes sapidus. MrProAE-III mRNA and enzyme activity of MrProAE-III were detectable in all examined tissues, including hepatopancreas, hemocytes, pleopods, walking legs, eye stalk, gill, stomach, intestine, brain and muscle with the highest level of both in hepatopancreas. This is regulated after systemic infectious hypodermal and hematopoietic necrosis virus infection supporting that it is an immune-responsive gene. These results indicate that MrProAE-III functions in the proPO system and is an important component in the prawn immune system.
Blue swimming crab, Portunus pelagicus is widely study and research throughout the Indo-West Pacific, but little is known of its reproductive biology in Malaysia. The present study describes the fecundity, embryonic development and ovarian development stages of the P. pelagicus from Johor coastal water, Malaysia. Carapace width range of berried crabs sampled was from 9.64 to 13.32 cm, while the body weight range was from 75 to 235 g. The mean number of egg produced by females in different sizes ranged from 105443.333 +/- 35448.075 per eggs batch. Mean egg size during embryonic development at stage 1 was 0.307 +/- 0.037, while 0.386 +/- 0.039 and 0.396 +/- 0.033 for stage 2 and stage 3, respectively. Study showed that there was significant (p < 0.05) relationship between the number of eggs and carapace width/body weight. Mean diameter oocyte during ovarian development at stage 1 was 97.732 +/- 12.391 while for stage 2 was 149.516 +/- 23.287. Stage 3 showed increasingly of size with mean diameter was 158.506 +/- 27.616 and 181.013 +/- 24.339 for stage 4.
Crab is an important source of food allergen. Tropomyosin represents the main crab allergen and is responsible for IgE cross-reactivity between various species of crustaceans. Recently, other new crab allergens including arginine kinase have been identified. However, information on allergens of the local Portunidcrab is not available. Thus, the aim of this study was to identify the major allergens of Portunus pelagicus (blue swimming crab) using the allergenomics approach. Raw and cooked extracts of the crab were prepared from the crab meat. Protein profile and IgE binding pattern were demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from 30 patients with crab allergy. The major allergens of the crab were then identified by two-dimensional electrophoresis (2-DE), followed by mass spectrometry analysis of the peptide digests. The SDS-PAGE of raw extract revealed approximately 20 protein fractions over a wide molecular weight range, while cooked extract demonstrated fewer protein bands. The raw extract also demonstrated a higher number of IgE reactive bands than the cooked extract. A heat-resistant protein of 36 kDa has been identified as the major allergen in both raw and cooked extracts. In addition, a heat-sensitive protein of 41 kDa was also recognized as a major allergen in raw crab. The 2-DE gel profile of the raw extract demonstrated about >100 distinct proteins spots and immunoblotting of the 2-DE profile demonstrated at least 12 different major IgE reactive spots with molecular masses between 13 to 250 kDa and isoelectric point (pI) values ranging from 4.0 to 7.0. The 36 and 41 kDa proteins were identified as the crab tropomyosin and arginine kinase, respectively by mass spectrometry. Therefore, this study confirmed that tropomyosin and arginine kinase are the major allergens of the local Portunid crab, P. pelagicus.
Tropomyosin and arginine kinase have been identified as the major allergens in multiple species of crab. Charybdis feriatus is an important commercial crab in this country.
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.
A primary factor in population management and wildlife conservation is the delineation of population units derived from descriptions of population genetic structure. Yet, predicting factors that influence the patterns of gene flow in a population particularly at landscape scales remains a major challenge in evolutionary biology. Here we report a population genetic study of the mud crab Scylla olivacea examined based on a 542 bp segment of the mitochondrial DNA cytochrome c oxidase I gene among 91 individuals from six localities in the west and east coast of Peninsular Malaysia. In total 55 unique haplotypes were distinguished with 45 private haplotypes and a single common haplotype shared among all populations studied. The other ten haplotypes were shared among various populations. The sharing of this haplotype reflects the connection of the mangrove areas between east and west coast of Peninsular Malaysia. High haplotype diversity (h = 0.968 ± 0.021; mean ± SD) and low nucleotide diversity (π = 0.120 ± 0.015; mean ± SD) were displayed, which may be indicative of genetic bottleneck events. No significant phylogenetic lineages were recognized using neighbour-joining and maximum parsimony methods. Hierarchical AMOVA analysis indicated that 99.33 % of the genetic variation was contained within populations and 0.67 % occurred among populations, suggesting no geographical patterning among populations studied, supported by F st test. Mismatch distribution analysis showed that the observed distribution of the pairwise mutation differences among haplotypes was multimodal, which is not concordant with a sudden range expansion scenario. However, neutrality tests showed non-significant negative values suggesting that the populations studied may have experienced past population growth, but the expansion may have been restricted to separate local areas that resulted in the non-significant negative Fu's Fs and Tajima's D value. Overall, this present preliminary study was able to be a reference on the phylogenetic relationships and assessment of genetic structure of Scylla sp. in Malaysia.
A new species of terrestrial sesarmid crab, Scandarma raymondi, is described from Sabah, Malaysia. This is the third species in the genus; others are from Taiwan, Japan and Sarawak, Borneo. The new species differs from congeners in the live coloration, proportions of the carapace and ambulatory legs and morphologies of the male abdomen, chela and male first gonopod.
Matched MeSH terms: Brachyura/anatomy & histology; Brachyura/classification*; Brachyura/growth & development
One of the major steps in the innate immune response of shrimp includes the activation of serine proteinases of the pro-phenoloxidase pathway by the prophenoloxidase activation enzyme (PPAF). In this study, the cDNA encoding a serine proteinase homologue (SPH) with prophenoloxidase activating activity of Penaeus monodon (PmPPAF) was cloned and characterized. PmPPAF cDNA consists of 1444 nucleotides encoding a protein with 394 amino acid residues. The estimated molecular weight of PmPPAF is 43.5 kDa with an isoelectric point of 5.19. PmPPAF consists of a signal peptide, a CLIP domain and a carboxyl-terminal trypsin-like serine protease domain. It is highly similar to the masquerade-like protein 2A (61% similarity) of the crayfish Pacifastacus leniusculus, other serine proteases (42.9-67% identity) of P. monodon, and the PPAF of the crab (61% similarity). Unlike other SPH of P. monodon, which express mainly in the hemocytes, PmPPAF transcripts were detected in the hemocytes, eyestalk, hypodermis, gill, swimming leg and brain. Similar to the crab PPAF, PmPPAF transcript level is high in shrimp at the premolt stages and PmPPAF expression is up-regulated in shrimp infected with white spot syndrome virus (WSSV). Gene silencing of PmPPAF decreased expression of a prophenoloxidase-like gene and injection of Anti-PmPPAF antibody causes a decrease in PO activity. Taken together, these results provided evidence that PmPPAF is a serine proteinase homologue, and is involved in the pro-PO activation pathway of the shrimp innate immune system.
The natural diet of blue swimming crabs, Portunus pelagicus, was investigated from October 2008 to October 2009 using hand sampling and a crab gill net. The results showed that the major prey items in the stomach contents of P. pelagicus were teleost fish (29.61%), organic matter (20.69%), crustaceans (18.3%) and shelled molluscs (11.46%). Significant differences were found in diet composition between juvenile and mature crabs, between crabs inside and outside the bay and among seasons. In contrast, significant differences were not found between male and female crabs.
A new species of Opecarcinus Kropp & Manning, 1987, is described from Indonesia and Malaysia. Opecarcinus cathyae sp. nov. is associated with the scleractinian corals Pavona clavus (Dana, 1846) and P. bipartita Nemenzo, 1980, inhabiting crescent-shaped cavities or tunnels on the coral surface. The new species is the ninth assigned to the genus. It can be separated from congeners by the anterolateral orientation of the cornea, the carapace with shallow transverse depressions, lacking longitudinal depressions, and the smooth dorsal margin of the fifth female pereiopod carpus. The distinctive colour pattern can be used as a diagnostic character in live specimens.
A new species of cave crab, Stygothelphusa antu new species, is described from limestone formations in Temurang, Sarawak, Malaysia. The new species is the most highly adapted to a cavericolous lifestyle among the four known species of Stygothelphusa, having a pale body pigmentation, reduced eyes and elongated pereopods. In contrast, the other three species have normal eyes that almost completely fill the orbits. The new species also differs from its congeners by a number of carapace, pereopod and gonopod characters.
The identity of the common lowland freshwater crab in western Sarawak, Borneo, East Malaysia, Parathelphusa oxygona Nobili, 1901 (family Gecarcinucidae), is clarified. The species is redescribed and figured, and its taxonomy discussed. Specimens from western Kalimantan, Borneo, Indonesia, which have been referred to P. oxygona are here referred to a new species, Parathelphusa nobilii. The new species can be differentiated from congeners by its relatively more swollen branchial regions of the carapace, wider and lower external orbital tooth, relatively more slender male abdomen and a straight male first gonopod.
Identifying potential food sources in mangrove ecosystems is complex because of the multifarious inputs from both land and sea. This study, which was conducted in the Manko mangrove ecosystem of Okinawa, Japan, determined the composition of the stable isotopes δ(13)C and δ(15)N in primary producers and macrozoobenthos to estimate the potential food sources assimilated and to elucidate the target trophic levels of the macrozoobenthos. We measured the two stable isotope signatures of three gastropods (Cerithidea sp., Cassidula mustelina, Peronia verruculata), two crabs (Grapsidae sp., Uca sp.), mangrove tree (Kandelia candel) leaves, and sediment from the mangrove ecosystem. The respective carbon and nitrogen isotope signature results were as follows: -22.4‰ and 8.6‰ for Cerithidea sp., -25.06‰ and 8‰ for C. mustelina, -22.58‰ and 8‰ for P. verruculata, -24.3‰ and 10.6‰ for unidentified Grapsidae, -21.87 ‰ and 11.5 ‰ for Uca sp., -29.81‰ and 11‰ for K. candel, and -24.23‰ and 7.2‰ for the sediment. The stable isotope assimilation signatures of the macrozoobenthos indicated sediment as their food source. Considering the trophic levels, the stable isotope values may also indicate that the five macrozoobenthos species were secondary or higher consumers.