Invasive snails in the genus Pomacea have spread across Southeast Asia including Peninsular Malaysia. Their effects on natural and agricultural wetlands are appreciable, but species-specific effects are less clear because of morphological similarity among the species. Our objective was to establish diagnostic characteristics of Pomacea species in Malaysia using genetic and morphological criteria. The mitochondrial COI gene of 52 adult snails from eight localities in Peninsular Malaysia was amplified, sequenced, and analysed to verify species and phylogenetic relationships. Shells were compared using geometric morphometric and covariance analyses. Two monophyletic taxa, P. canaliculata and P. maculata, occurred in our samples. The mean ratio of shell height: aperture height (P = 0.042) and shell height: shell width (P = 0.007) was smaller in P. maculata. P. maculata co-occurred with P. canaliculata in five localities, but samples from three localities contained only P. canaliculata. This study is the first to confirm the presence of two of the most invasive species of Pomacea in Peninsular Malaysia using a molecular technique. P. canaliculata appears to be the more widespread species. Despite statistical differences, both quantitative and qualitative morphological characteristics demonstrated much interspecific overlap and intraspecific variability; thus, shell morphology alone cannot reliably verify species identity. Molecular techniques for distinguishing between these two highly invasive Pomacea species are needed to understand their specific ecological niches and to develop effective protocols for their management.
Schistosomiasis is a neglected tropical disease that affects more than 200 million people worldwide. The main disease-causing agents, Schistosoma japonicum, S. mansoni and S. haematobium, are blood flukes that have complex life cycles involving a snail intermediate host. In Asia, S. japonicum causes hepatointestinal disease (schistosomiasis japonica) and is challenging to control due to a broad distribution of its snail hosts and range of animal reservoir hosts. In China, extensive efforts have been underway to control this parasite, but genetic variability in S. japonicum populations could represent an obstacle to eliminating schistosomiasis japonica. Although a draft genome sequence is available for S. japonicum, there has been no previous study of molecular variation in this parasite on a genome-wide scale. In this study, we conducted the first deep genomic exploration of seven S. japonicum populations from mainland China, constructed phylogenies using mitochondrial and nuclear genomic data sets, and established considerable variation between some of the populations in genes inferred to be linked to key cellular processes and/or pathogen-host interactions. Based on the findings from this study, we propose that verifying intraspecific conservation in vaccine or drug target candidates is an important first step toward developing effective vaccines and chemotherapies against schistosomiasis.
Love darts are hard 'needles' that many snails and slugs use to pierce their partner during mating. In a few species, darts have been shown to play a role in sperm competition. Two new papers, by Davison et al., and Koene and Schulenburg, might further pique researchers' interest, because they show how the full potential of darts can be tapped for studies of sexual selection in hermaphrodites.
A study of heavy metal contents in freshwater snails from rice fields have been made. The results indicate that the levels of heavy metals, Pb, Cu, Zn and Cd, are low and within the permissible limit of Malaysian Food Regulations. The results can serve as background data for further reference.
The objective of this study is to establish conditions that allow optimal yield and antioxidant
activity for Golden Apple Snail (GAS) (Pomacea canaliculata) protein hydrolysate by employing
response surface methodology (RSM). A three level, face-centered, central composite design
(CCD) was adapted to assess the effects of temperature (45–65˚C); pH (8–10); the ratio of
enzyme to substrate (2–4%); and hydrolysis time (60–180 min). The antioxidative activity
of the hydrolysate obtained under optimized conditions was then evaluated via the following
metrics: hydroxyl radical scavenging, reducing power, and chelating effects on ferrous ion.
Established optimal conditions for the enzymatic protein hydrolysis of GAS were a temperature
of 45˚C, a pH of 10, an enzyme concentration of 2%, and hydrolysis time of 159 minutes. The
optimized GAS protein hydrolysate produced an experimental yield of 9.72% and antioxidant
activity of 73.54%—slightly less than the predicted yield of 11.36% and antioxidant activity of
78.88%. The optimized GAS protein hydrolysate formed demonstrated both higher chelating
effects and hydroxyl scavenging activity but had lower reducing power. These results suggest
that GAS protein hydrolysate holds potential as a natural antioxidant for use in food processing.
The purpose of this paper was to provide a practical guide assisting field workers in identification and interpretation of frequently occurring bioerosional textures created in limestone by intertidal organisms along the coasts of Langkawi Islands, Malaysia. The discussion follows the textural succession from the supratidal down to the lower intertidal zone. Traces left by lichens, boring sponges, molluscs (littorinid snails, the chiton Acanthopleura, the bivalve Lithophaga) and the echinoid Echinometra are illustrated. Products of bioconstructing organisms, specifically oysters and barnacle are also described. Ecological tolerance of each group is given.
Limestone hills are now gaining global conservation attention as hotspots for short-range endemic species. Levels of land snail endemism can be high at limestone hills, especially at hill clusters that are geographically isolated. In the State of Perak, Peninsular Malaysia, limestone hills have been opportunistically surveyed for land snails in the past, but the majority have yet to be surveyed. To address this knowledge gap, we systematically surveyed the terrestrial malacofauna of 12 limestone hills that, based on our opinion, are a representation of the limestone land snail assemblages within the State. Our inventory yielded high sampling completeness (>85%). We found 122 species of land snails, of which 34 species were unique to one of the surveyed hills. We identified 30 species that are potentially new to science. The number of land snail species recorded at each hill ranged between 39 and 63 species. Four of the sampled limestone hills namely, Prk 01 G. Tempurung, Prk 55 G. Pondok, Prk 47 Kanthan, and Prk 64 Bt Kepala Gajah, have high levels of species richness and unique species, representing 91% of the total species recorded in this study. We identified two clusters of limestone hills in central Perak with distinct differences in land snail species composition - a northern hill cluster on elevated granite bedrock and southern hill cluster in a low-lying valley surrounded by alluvial soils. As limestone hills continue to be quarried to meet the cement demand, the four identified limestone hills, along with other hills from the two clusters, warrant urgent conservation attention in order to maintain high species diversity within Perak's terrestrial malacofauna.
Schistosomiasis in Southeast Asia, caused by Schistosoma japonicum, Schistosoma mekongi and Schistosoma japonicum-like, have been reported from six different countries. The S. japonicum infections are highly prevalent in the Philippines with Oncomelania hupensis quadrasi as the vector snail, and in localized areas in Indonesia with O.h. lindoensis as the snail vector. The S. mekongi infections are recent discovery in the Lower Mekong Basin in Laos and Kampuchea, with Tricula aperta as the vector snail. The S. japonicum-like infections are found as isolated cases diagnosed by the finding of S. japonicum-like eggs in the faeces, rectal biopsy, tissue biopsy or at necropsy in Thailand and Malaysia. The control measures of schistosomiasis have been implemented in the Philippines and Indonesia, while further research studies are being conducted in Thailand and Malaysia.
As part of a search for novel inhibitors of HIV-1 reverse transcriptase, the acetone extract of the giant African snail, Achatina fulica, was shown to be active. Fractionation of the extract yielded inophyllums A, B, C, and E and calophyllolide (1a, 2a, 3a, 3b, and 6), previously isolated from Calophyllum inophyllum Linn., a known source of nutrition for A. fulica. From a methanol/methylene chloride extract of C. inophyllum, the same natural products in considerably greater yield were isolated in addition to a novel enantiomer of soulattrolide (4), inophyllum P (2b), and two other novel compounds, inophyllums G-1 (7) and G-2 (8). The absolute stereochemistry of inophyllum A (1a) was determined to be 10(R), 11(S), 12(S) from a single-crystal X-ray analysis of its 4-bromobenzoate derivative, and the relative stereochemistries of the other inophyllums isolated from C. inophyllum were established by a comparison of their 1H NMR NOE values and coupling constants to those of inophyllum A (1a). Inophyllums B and P (2a and 2b) inhibited HIV reverse transcriptase with IC50 values of 38 and 130 nM, respectively, and both were active against HIV-1 in cell culture (IC50 of 1.4 and 1.6 microM). Closely related inophyllums A, C, D, and E, including calophyllic acids, were significantly less active or totally inactive, indicating certain structural requirements in the chromanol ring. Altogether, 11 compounds of the inophyllum class were isolated from C. inophyllum and are described together with the SAR of these novel anti-HIV compounds.
Snail is one of the worst causes of food allergy. Thus, the aim of this study was to identify the major and minor allergens of the local marine snail (Cerithidea obtusa) and subsequently to investigate the impacts of heat treatment on the IgE-binding activity of snail allergens. Proteins from raw and heat-treated snails (boiled, roasted and fried) were extracted and then resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunoblotting of all extracts were then performed using sera from patients with snail allergy. The results showed that the raw extract contains numerous protein bands between 12 to>250 kDa. Some thermostable proteins, predominantly the 33 and 42 kDa bands, remained detected in all cooked extracts with decreasing intensities from boiled to roasted to fried extracts, while the majority of thermolabile bands denatured after heating. Boiled snail had more protein bands compared to roasted and fried snails. Immunoblotting of raw extract demostrated 19 IgE-binding bands ranging from 15 to 240 kDa. The thermostable bands of 33 and 42 kDa and a thermolabile of 30 kDa band were identified as the major allergens of this snail. The cooked extracts yielded less allergenic bands. The boiled extract yielded approximately 14 IgE-binding bands with some smeared bands at high molecular weight regions. The roasted extract had lesser IgE-binding bands and the majority appeared as smears, while the IgE-reactivity in the fried extract was less visible and appeared as weak smears. This study indicated that both raw and cooked snails played a crucial role in snail allergenicity, as this species of snail contains both thermostable and thermolabile major allergens. The degree of snail allergenicity was revealed in the order: raw> boiled > roasted> fried. Thus, the results would facilitate in the development of effective diagnosis and management strategies of snail allergy in this country.
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.
A survey of Angiostrongylus malaysiensis among wild rodent and molluscan hosts was made in the Tuaran Central Agricultural Research Station and within the vicinity of Tuaran, Sabah. Three of 19 Rattus rattus diardii, one of 2 R. exulans and one R. argentiventer were found naturally infected with the parasite. In this survey 56 of 382 molluscs comprising of Pila scutata, Achatina fulica and two species of land slugs, Laevicaulis alte and Microparmarion malayanus, were found naturally infected with the parasite. Samples of larvae from each of these molluscs were experimentally transferred to laboratory albino rats and adult worms consistent with A. malaysiensis were recovered. Comparison of the rat hosts and the molluscan intermediate hosts of the parasite in Peninsular Malaysia, Sarawak and Sabah was made, and the finding of A. malaysiensis in Tuaran is the first report of the parasite from Sabah. The distribution of the parasite throughout Malaysia is discussed. Observation on the human consumption of the freshwater snail, P. scutata, was made. Although the infection rate of this snail is low compared with other molluscan hosts examined. The importance of this mollusc as a potential source of human infection should not be overlooked. Hospital records for 1974 and 1975 were examined and clinical human angiostrongyliasis was rarely recorded in Sabah.
This study was conducted to assess the reliability of Nerita lineata as a bioindicator for metals in sediment and the factors influencing the accumulation of metals and methylmercury in its soft tissue. The two matrices were analyzed for Co, Cr, Cu, THg, MeHg, Mn, Ni, Pb, and Zn. The metal concentrations in N. lineata were comparable to previously reported results with the exception of Ni which was higher. Cu, Mn, and Pb in N. lineata were significantly (p