Category Archives: Publications

Authors: PS Dharmadasa, GY Liyanage, PM Manage
Journal: Journal of Tropical Forestry and Environment

Pollution reaches its most serious proportion in past few decades and adversely effect on animals and human health. Reduction of pollutant in the environment take place with microbial metabolism and remediation studies by microbes have proved their feasibility on clean up the contaminated environment. Thus, the present study reports the biodegradation of Micocystins (MC-LR) and antibiotics [Oxytetracycline (OTC) and Ampicillin (AMP)] by Bacillus cereus, Enterobacter ulcerans, Enterobacter sp. and Micrococcus sp. strains which were previously reported as potential crude oil degraders.  A 0.5 ml of overnight starved bacterial suspensions was introduced into medium containing antibiotic (OTC, AMP) at 60 µg/ml and Microcystin-LR at 10 µg/ml respectively. Triplicate samples were incubated at 28⁰C while shaking at 100 rpm. A 0.5 ml of aliquots was removed at 2 days interval for a period of 14 days and analysis was done by High Performance Liquid Chromatography (HPLC). The highest degradation of MC- LR was shown by Micrococcus sp. (97%) where as other stains; E. ulcerans (96 %), Enterobactor sp. (95 %) and B. cereus (88%) also showed comparative high degradation after 14 days of incubation. B. cereus, Enterobacter sp. and Micrococcus sp. were identified as AMP resistance bacteria and degraded AMP at 81%, 22% and 39% respectively. It was found that B. cereus was resistance to OTC and showed 56% reduction at 14 days of incubation. The results of the present study revealed that the bioremediation potential of harnessing microbes can cleanup of pollutant in the environment and use as eco friendly tool for removal of environmental pollutants.

Authors: Beneeta Jayawardena, Gayani  Senevirathne, Nayana Wijayathilaka, Kanishka Ukuwela, Kelum Manamendra-Arachchi and Madhava Meegaskumbura
Journal: Ceylon Journal of Science

Species boundaries and patterns of gene flow in Dwarf toads, Duttaphrynus scaber and D. atukoralei, were assessed using mitochondrial DNA markers. Samples from four populations in Sri Lanka (Mihintale, Ampara, Yala, Galle) were analyzed for three mitochondrial gene fragments (16S rRNA, COI and Cyt b) along with four Genbank sequences of 16S rRNA from Indian samples (Thiruvananthapuram, Maharashtra, Mudigere). Phylogenetic trees and haplotype networks were generated, and morphology was assessed. Analyses suggest a single species (Duttaphrynus scaber) with three major clades: a widespread clade shared between India and Northern Sri Lanka, an Eastern and Southeastern Sri Lankan clade (previously referred to as D. atukoralei, the validity of which, however, our analysis disputes), and a distinct Southern wet-zone clade from Galle (referred previously to as D. atukoralei). Duttaphrynus atukoralei (topotypes from Yala, Sri Lanka) is genetically too close to  (Indian and northern Sri Lankan clade) to be distinguished as a species; these two clades have a genetic distance of 0.95 – 1.55% for the 16S rRNA fragment. The haplotype networks for the 16S rRNA gene suggest incomplete lineage sorting between the Ampara and Yala populations; COI and Cyt b show complete sorting for all populations analyzed, suggesting strong population structure. All analyses suggest substantially restricted gene flow to the southern wet-zone population (Galle). This population also assumes a basal phylogenetic position, suggesting that D. scaber first evolved in southern Sri Lanka’s wet zone and dispersed across the lowland areas of the island and to India. Here, we provisionally recognize this population (Galle) as an evolutionarily significant unit of D. scaber; future analyses using multiple criteria may indicate this to be a new Dwarf toad species. External morphology is largely uninformative as the Yala, Ampara and Galle populations cannot be distinguished from each other; the morphological distinction between Yala, Ampara, Galle versus Mihintale is restricted to only the shape of the parotid glands – slightly oval versus rounded – a minor difference. Both genetic and morphological evidence so far suggest that there is only a single Dwarf toad species in Sri Lanka, which is also shared with India, namely Duttaphrynus scaber; however, with strong population structure, including an evolutionarily significant unit (Southern wet-zone population).

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Authors: Prof. Dinithi Champika Peiris, Thamali Dhanushka
Journal: Environmental Science and Pollution Research

Use of pesticides results in indirect effects on human health. We aimed to evaluate implications of toxicological effects of subchronic chlorpyrifos exposure on reproductive function in male rats. A total of 48 adult Wistar male rats were separated into four groups (n = 12). Animals were gavaged with 2.5 mg/kg (T1), 5 mg/kg (T2), or 10 mg/kg (T3) body weight of chlorpyrifos (CPF) or distilled water (control) daily for 30 days. Organ weights, epididymal sperm parameters, DNA integrity, sex hormonal (FHS and LH) levels, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and creatinine concentrations were determined on day 31. Another two sets of (four groups/set; n = 10) animals were orally treated with the same doses of CPF, control animal groups were treated with distilled water only for 30 days, and fertility indices and blood plasma acetylcholine esterase (AchE) were determined on day 31. Exposure to CPF resulted in a significant (p < 0.05) decrease in weights of testis and epididymis. An increase in liver weight resulted in reduced sperm counts and sperm motility and an increase in sperm abnormalities. Significant reduction in serum testosterone (p < 0.01), luteinizing hormone (p < 0.05), and follicular stimulating hormone (p < 0.05) levels was evident in animals treated with the highest dose. A significant decrease in the number of viable implantation sites and pups was observed in female rats mated with the T3 (p < 0.01) and T2 (p < 0.05) males. The ALT, AST, GGT, and creatinine contents were significantly increased (p < 0.05 and p < 0.01, respectively) on CPF exposure. A significant (p < 0.01) reduction in blood plasma AchE enzyme was observed with the highest dose. Our results demonstrated that prolonged exposure of CPF induces spermatogenesis damage, possibly through interference with sex hormones and AchE enzyme resulting in reduction of fertility. Therefore, awareness programs on handling CPF (pesticides) to enhance safety warrant minimization of its hazards.

Authors: WKDL Hegoda , Fernando HSD and Prof. BGDNK de Silva
Journal: Journal of Entomology and Zoology Studies

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