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Nishimura M.,Okinawa Prefectural Institute of Health and Environment
International Journal of Tropical Medicine | Year: 2011

Practical cheap tools are required to protect the inhabitants of the Okinawa and Amami islands, Japan against encounters and bites of the venomous pit viper snake Habu (Protobothrops flavoviridis) in their houses and the surrounding environment. In this study, the researchers conducted laboratory and field experiments to identify the most effective net settings (i.e., mesh size and short supported nets versus long unsupported nets) for capturing Habu. We found that short net-traps of approximately 1 min length with 25 mm mesh were the most effective with Habu being captured at a rate of > 1 snake per 10m net length per year in the field. This tool which is cheap and easy to maintain, entangles few non-target animals and applicable to reduce risk of other venomous snake species permanently in residential and farming areas. © Medwell Journals, 2011. Source

Aird S.D.,Okinawa Institute of Science and Technology | Watanabe Y.,Okinawa Institute of Science and Technology | Villar-Briones A.,Okinawa Institute of Science and Technology | Roy M.C.,Okinawa Institute of Science and Technology | And 2 more authors.
BMC Genomics | Year: 2013

Background: Advances in DNA sequencing and proteomics have facilitated quantitative comparisons of snake venom composition. Most studies have employed one approach or the other. Here, both Illumina cDNA sequencing and LC/MS were used to compare the transcriptomes and proteomes of two pit vipers, Protobothrops flavoviridis and Ovophis okinavensis, which differ greatly in their biology. Results: Sequencing of venom gland cDNA produced 104,830 transcripts. The Protobothrops transcriptome contained transcripts for 103 venom-related proteins, while the Ovophis transcriptome contained 95. In both, transcript abundances spanned six orders of magnitude. Mass spectrometry identified peptides from 100% of transcripts that occurred at higher than contaminant (e.g. human keratin) levels, including a number of proteins never before sequenced from snakes. These transcriptomes reveal fundamentally different envenomation strategies. Adult Protobothrops venom promotes hemorrhage, hypotension, incoagulable blood, and prey digestion, consistent with mammalian predation. Ovophis venom composition is less readily interpreted, owing to insufficient pharmacological data for venom serine and metalloproteases, which comprise more than 97.3% of Ovophis transcripts, but only 38.0% of Protobothrops transcripts. Ovophis venom apparently represents a hybrid strategy optimized for frogs and small mammals. Conclusions: This study illustrates the power of cDNA sequencing combined with MS profiling. The former quantifies transcript composition, allowing detection of novel proteins, but cannot indicate which proteins are actually secreted, as does MS. We show, for the first time, that transcript and peptide abundances are correlated. This means that MS can be used for quantitative, non-invasive venom profiling, which will be beneficial for studies of endangered species. © 2013 Aird et al.; licensee BioMed Central Ltd. Source

Igawa T.,Hiroshima University | Oumi S.,Section of Agriculture and Forest | Katsuren S.,Okinawa Prefectural Institute of Health and Environment | Sumida M.,Hiroshima University
Heredity | Year: 2013

Isolation by distance and landscape connectivity are fundamental factors underlying speciation and evolution. To understand how landscapes affect gene flow and shape population structures, island species provide intrinsic study objects. We investigated the effects of landscapes on the population structure of the endangered frog species, Odorrana ishikawae and O. splendida, which each inhabit an island in southwest Japan. This was done by examining population structure, gene flow and demographic history of each species by analyzing 12 microsatellite loci and exploring causal environmental factors through ecological niche modeling (ENM) and the cost-distance approach. Our results revealed that the limited gene flow and multiple-population structure in O. splendida and the single-population structure in O. ishikawae were maintained after divergence of the species through ancient vicariance between islands. We found that genetic distance correlated with geographic distance between populations of both species. Our landscape genetic analysis revealed that the connectivity of suitable habitats influences gene flow and leads to the formation of specific population structures. In particular, different degrees of topographical complexity between islands are the major determining factor for shaping contrasting population structures of two species. In conclusion, our results illustrate the diversification mechanism of organisms through the interaction with space and environment. Our results also present an ENM approach for identifying the key factors affecting demographic history and population structures of target species, especially endangered species. © 2013 Macmillan Publishers Limited All rights reserved. Source

Blanco A.C.,Tokyo Institute of Technology | Blanco A.C.,University of the Philippines at Diliman | Nadaoka K.,Tokyo Institute of Technology | Yamamoto T.,Tokyo Institute of Technology | Kinjo K.,Okinawa Prefectural Institute of Health and Environment
Hydrological Processes | Year: 2010

Excessive terrestrial nutrient loadings adversely impact coral reefs by primarily enhancing growth of macroalgae, potentially leading to a phase-shift phenomenon. Hydrological processes and other spatial and temporal factors affecting nutrient discharge must be examined to be able to formulate effective measures for reducing nutrient export to adjacent reefs. During storm events and baseflow periods, water samples were obtained from the tropical Todoroki River, which drains an intensively agricultural watershed into Shiraho coral reef. In situ nutrient analyzers were deployed for 6 months to hourly measure dissolved nutrient (NO3 --N and PO4 3--P) concentrations. Total phosphorus (TP) and suspended solid concentration (TSS) were increased by higher rainfall intensity (r = 0·94, p < 0·01) and river discharge Q (r = 0 88, p < 0 01). In contrast, NO3 --N concentration tends to decrease drastically (e.g. from 3 to 1 mg l-1) during flood events. When base flow starts to dominate afterwards, NO3 --N manifested an increasing trend, but decreases when baseflow discharge becomes low. This counter-clockwise hysteresis for NO3 --N highlights the significant influence of groundwater discharge. N delivery can therefore be considered a persistent process compared to sediment and P discharge, which are highly episodic in nature. Based on GIS analysis, nutrient concentration along the Todoroki River was largely affected by the percentage of sugarcane/bare areas and bedrock type. The spatial distribution of N concentration in the river reflects the considerable influence of subsurface geology-higher N levels in limestone-dominated areas. P concentrations were directly related to the total length of artificial drainage, which enhances sediment transport. The use of high-resolution monitoring data coupled with GIS-based spatial analysis therefore enabled the clarification of control factors and the difference in the spatio-temporal discharge characteristics between N and P. Thus, although erosion-reduction schemes would reduce P discharge, other approaches (e.g. minimize fertilizer) are needed to reduce N discharge. Copyright © 2010 John Wiley & Sons, Ltd. Source

Ishihara Y.,Tohoku University | Lee N.,Tohoku University | Oshiro N.,Okinawa Prefectural Institute of Health and Environment | Matsuoka S.,University of Tokyo | And 3 more authors.
Chemical Communications | Year: 2010

Ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, are potent neurotoxic polycyclic ethers. We report herein the total synthesis of a 10-membered F-ring analogue of 51-hydroxyCTX3C, which constitutes the first example of an F-ring modified ciguatoxin that exhibits potent cytotoxicity as well as mouse acute toxicity. © The Royal Society of Chemistry 2010. Source

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