New analysis sinks eight shrub frogs but finds 14 putative new species

8shrubfrogs

Authors: Gajaba Ellepola, Jayampathi Herath, Kelum Manamendra-Arachchi, Nayana Wijayathilaka, Gayani Senavirathne, Rohan Pethiyagoda and Madhava Meegaskumbura.

Journal: Plosone

Sri Lanka is an amphibian hotspot of global significance. Its anuran fauna is dominated by the shrub frogs of the genus Pseudophilautus. Except for one small clade of four species in Peninsular India, these cool-wet adapted frogs, numbering some 59 extant species, are distributed mainly across the montane and lowland rain forests of the island. With species described primarily by morphological means, the diversification has never yet been subjected to a molecular species delimitation analysis, a procedure now routinely applied in taxonomy. Here we test the species boundaries of Pseudophilautus in the context of the phylogenetic species concept (PSC). We use all the putative species for which credible molecular data are available (nDNA–Rag-1; mt-DNA– 12S rRNA, 16S rRNA) to build a well resolved phylogeny, which is subjected to species delimitation analyses. The ABGD, bPTP, mPTP and bGMYC species delimitation methods applied to the 16S rRNA frog barcoding gene (for all species), 12S rRNA and Rag-1 nDNA grouped P. procax and P. abundus; P. hallidayi and P. fergusonianus; P. reticulatus and P. pappilosus; P. pleurotaenia and P. hoipolloi; P. hoffmani and P. asankai; P. silvaticus and P. limbus; P. dilmah and P. hankeni; P. fulvus and P. silus.. Surprisingly, all analyses recovered 14 unidentified potential new species as well. The geophylogeny affirms a distribution across the island’s aseasonal ‘wet zone’ and its three principal hill ranges, suggestive of allopatric speciation playing a dominant role, especially between mountain masses. Among the species that are merged by the delimitation analyses, a pattern leading towards a model of parapatric speciation emerges ongoing speciation in the presence of gene flow. This delimitation analysis reinforces thespecies hypotheses, paving the way to a reasonable understanding of Sri Lankan Pseudophilautus, enabling both deeper analyses and conservation efforts of this remarkable diversification.

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Modified, optimized method of determination of Tributyltin (TBT) contamination in coastal water, sediment and biota in Sri Lanka

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Authors: K.R.V. Bandara, S.D.M. Chinthaka, S.G. Yasawardene and Pathmalal M. Manage

Journal: Marine Pollution Bulletin

Tributyltin (TBT) is a toxic organotin compound that belongs to the group of Persistent Organic Pollutants (POPs) and it is documented to cause severe sexual disorders development in aquatic fauna. According to the present study, The TBT concentration in coastal water ranged from 303 ± 7.4 ngL− 1 to 25 ± 4.2 ngL− 1 wherein sediment was from 107 ± 4.1 ngKg− 1 to 17 ± 1.4 ngKg− 1 . TBT in Perna viridis was found to range from 4 ± 1.2 ngKg− 1 to 42 ± 2.2 ngKg− 1 wet weight and in ascending order of the body weight. The highest TBT level in water and sediment was found in the Colombo port where the highest level of TBT in P. viridis (42 ± 2.2 ngKg− 1 ) was recorded from the Dikkowita fishery harbor. A positive correlation between the number of male P. viridis and TBT level (p < 0.05) suggests possible reproductive impairment in aquatic animals exposed continuously to a high concentration of TBT.

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Isolation and Identification of Cellulase Producing and Sugar Fermenting Bacteria for Second-Generation Bioethanol Production

 

biofuel

Authors: L.I. Weerasinghe, Tharindu Madusanka and Pathmalal M. Manage

Journal: International Journal of Renewable Energy Development

Over the last decades, the negative impacts of fossil fuel on the environment and increasing demand for energy due to the unavoidable depletion of fossil fuels, has transformed the world’s interests towards alternative fuels. In particular, bioethanol production from cellulosic biomass for the transportation sector has been incrementing since the last decade. The bacterial pathway for bioethanol production is a relatively novel concept and the present study focused on the isolation of potential “cellulase-producing” bacteria from cow dung, compost soil, and termite gut and isolating sugar fermenting bacteria from palm wine. To select potential candidates for cellulase enzyme production, primary and secondary assays were conducted using the Gram’s iodine stain in Carboxy Methyl Cellulose (CMC) medium and the Dinitrosalicylic acid (DNS) assays, respectively. Durham tube assay and Solid-Phase Micro-Extraction (SPME) coupled with Gas Chromatography-Mass Spectrometry (GC-MS) was used to evaluate the sugar fermenting efficiency of the isolated bacteria. Out of 48 bacterial isolates, 27 showed cellulase activity where Nocardiopsis sp. (S-6) demonstrated the highest extracellular crude enzyme activity of endoglucanase (1.56±0.021 U) and total cellulase activity (0.93±0.012 U). The second-highest extracellular crude enzyme activity of endoglucanase (0.21±0.021 U) and total cellulase activity (0.35±0.021 U) was recorded by Bacillus sp. (T-4). Out of a total of 8 bacterial isolates, Achromobacter sp. (PW-7) was positive for sugar fermentation resulting in 3.07% of ethanol in broth medium at 48 h incubation. The results of the study revealed that Nocardiopsis sp. (S-6) had the highest cellulase enzyme activity. However, the highest ethanol percentage was achieved with by having both Bacillus sp. (T-4) and Achromobacter sp. (PW-7) for the simultaneous saccharification and fermentation (SSF) method, as compared to separate hydrolysis and fermentation (SHF) methodologies

Spatiotemporal distribution of cutaneous leishmaniasis in Sri Lanka and future case burden estimates

journal-pntd-0009346-g001Authors: Nadira D. Karunaweera, Sanath Senanayake, Samitha Ginige, Hermali Silva, Nuwani Manamperi, Nilakshi Samaranayake, Rajika Dewasurendra, Panduka Karunanayake, Deepa Gamage, Nissanka de Silva, Upul Senarath, Guofa Zhou

Journal: PLoS Negl Trop Dis

Leishmaniasis is on the rise in Sri Lanka in contrast to the declining trend in rest of South Asia. Spatiotemporal analysis and disease risk factors are useful for understanding transmission mechanisms and predicting future disease distribution to facilitate control. In this study we analyzed data on cutaneous leishmaniasis cases from Sri Lanka from 2001 to 2019. We asked three important questions regarding the driving forces behind the intensified leishmaniasis transmission: 1) Are the transmission dynamics in different areas synchronized? 2) What is the role of neighboring-area dispersal in shaping transmission dynamics? 3) How important is climatic variability in transmission dynamics? We used a multi-step approach to answer these questions. In addition to cross-correlation analysis, we built a mixed spatiotemporal regression-autoregression model to analyze risk factors, which is unique in leishmaniasis research because the simplified model was also useful for predicting future disease distribution. We found that the incidence dynamics in different districts could be divided into three synchronized groups based on similarity. Risk factor analysis indicated that precipitation, neighboring-district dispersal, and local infection carryover played important roles in shaping transmission dynamics. The spatiotemporal model predicted intensifying transmission with increasing case numbers, and expansion of high-transmission areas. Targeted interventions are urgently needed to stem the outbreak.

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