My areas of research interest are; Biology, Marine Science, Biotechnology, Molecular Biology, Analytical Chemistry, and Ecological and Biodiversity Conservation Studies.
ONGOING RESEARCH
Distribution, Taxonomy and Conservation of the Millipede Fauna of Sri Lanka
Millipedes (Sinhalese; Hakaralla) are group of arthropods (invertebrates with jointed limbs) that are characterised by having two pairs of jointed legs on most body segments, which differ from centipedes as they having one pair of legs per body segments. Most of the animal in this group have very elongated cylindrical or flattened bodies with the segments, although pill millipedes are shorter and can roll into a ball (In Sinhalese; Kithula ataya, Hakuru bole and Handunkaraduwa.
Swiss naturalist Aloïs Humbert (1865) was the first person to document the millipedes of Sri Lanka reporting 26 species, including 19 new species. In 1981, Jean-Paul Mauriès reported the only endemic family of millipedes from Sri Lanka, Lankasomatidae, while Richard Hoffman (1997) reported the only endemic genus from Sri Lanka, Singhalocryptus. All known millipede species reported in Sri Lanka have been described by foreign scientists during the last 150 years and consequently, the Sri Lankan Diplopoda checklist was updated to a total of 103 species belonging to 17 families, 43 genera and 82 species are endemic to Sri Lanka. Most of the millipede species have been recorded from a few localities in the central highlands of Sri Lanka during the colonial era. Thus, the diversity could be higher than currently known if other localities are sampled.
Currently, Faculty of Technology and Faculty of Applied Sciences, Rajarata University of Sri Lanka are conducting an Islandwide collaborative survey on “Diversity, Distribution and Taxonomy of Millipedes in Sri Lanka”. It is expected that after the survey, we will have a better understanding on the total diversity, distribution and the conservation status of the millipede fauna.
PAST RESEARCH ACTIVITIES
Analysis of the prostaglandin pathway gene expression in Skeletonema marinoi [2019/20].
This study was focused on the understanding of prostaglandin (PG) pathway of Skeletonema marinoi grown under light stress conditions. Lipids derived molecules are one of the most important molecules derived from diatoms and microalgae in general, whose composition varies from 1 % to 85 % of their dry weight. PGs belong to biologically active lipid derivatives family. Also, PGs are considered as lipid autacoids derived from AA or EPA and they have both homeostatic functions and ability to mediate pathogenic mechanisms including the inflammatory response in the cells. The biosynthesis of PGs occurs only in the presence of the COX enzyme. Inside the cells, there are two types of isoforms of COX enzyme, and those differ by the localization in the cells. Besides, no studies have revealed to what extent those mechanisms are used by diatoms to overcome stress adaptations. Hence, the overall aim of this study is to understand the expression of the main enzyme of the prostaglandin pathway (COX- 1) of FE7 strain of S. marinoi under stress conditions such as high light and low light using the comparative gene expressions by Reverse Transcription-quantitative PCR (RT-qPCR).
This study reveals how the expression of the COX-1 gene, which is the main enzyme responsible for the biosynthesis of the PGs in S. marinoi, is regulated by exposure to light stress conditions (low light (LL) and high light (HL)) with different exposure times. In conclusion, this study confirms the modulation of the expression of PGs biosynthesis pathway with the involvement of the expression of COX-1 gene in the S. marinoi. The longer exposure under both LL and HL upregulate the COX-1 expression but it is relatively higher with LL conditions than the HL. However, further studies of PG biosynthesis in different strains of S. marinoi are also very important to understand the possible variability of biosynthesis of PGs at the clone level. Besides, this identification of expression with light stress may become helpful to develop cheaper methods for large scale extraction of PGs from natural sources, creating a new opportunity for the pharmaceutical industries as diatoms are most successful groups of organisms in the world.
Effect of Feeding Habits and Habitats on Fatty Acids Profile of Ehirava fluviatilis (Malabar Sprat)in Sri Lanka [2015-2018].
The E. fluviatilis is a clupeid found in Southern India and Sri Lanka, and their distribution is limited to the South-west part of the coastline of Sri Lanka including the Negombo lagoon and Bolgoda Lake (Brackish water body). They are also inhabited to the Parakarama Samudra and Rajanaganaya freshwater in mainly two reservoirs as secondarily colonised habitats. Therefore, this study was carried out to collect baseline information focusing on the impact of fatty acid profiles of their foods and flesh of E. fluviatilis fish species in the Bolgoda Lake and Rajanganaya reservoirs in Sri Lanka. When comparing the food and stomach content of this species, the only recorded difference from both populations was presence of C 18:2 (n-4) in the Rajanganaya reservoir population. Thus, it was revealed this study that the presence of specific FAs could be used as biomarkers to identify species. It may also be hypothesized that the difference in the FA profile may lead to colonization of marine origin E. fluviatilis in Rajanganaya reservoir as a freshwater lacustrine habitat.
De Zoysa, H.K.S., Amarasinghe U.S., Edirisinghe, E.M.R.K.B. & T.V. Sundarabarathy. (2019). Habitat related variations and comparison of fatty acid composition of muscle and stomach contents of secondarily colonized Malabar Sprat (Ehirava fluviatilis) in Sri Lanka. NeBIO, An international journal of environment and biodiversity. 10(3): 152-163pp.
De Zoysa, H. K. S., Edirisinghe, E.M.R.K.B., Sundarabarathy, T.V. (2017). Fatty acid profiles of Malabar sprat (Ehirava fluviatilis) from brackish water and freshwater habitats in Sri Lanka, NARA Scientific Sessions – 2017, 57 pp.
Freshwater Crab Diversity and Distribution in Dry Zone, North Central Province, Sri Lankas [2015-2017]
Provincial survey has been conducted in the North Central Province (NCP), which focused on the diversity, distribution of freshwater crabs and the impacts of anthropogenic activities. During the survey that we found new distributional locations on the Oziothelphusa mineriyaensis in the NCP, Sri Lanka. The findings expand the extent of occurrence from 168 km2 to 1467 km2. Our new records are 62 km from the type locality and up to 89 km from the previous records in Anuradhapura District and 20 km from previous record in Polonnaruwa District. These data provide important new information needed for the conservation of this endangered species in Sri Lanka. Also, we found that main impacts on this creatures were pesticide as most of the farmers apply those for their fields and appearing of fragmented habitat due to developmental activities conducting without concern of this sensitive animals etc.,
De Zoysa, H. K. S., Samarasinghe, D. P., Dissanayake, D.S.B., Wellappuliarachi, S.M. & Wickramasinghe, S. (2017). Range extension of Oziothelphusa mineriyaensis Bott, 1970 (Decapoda, Gecarcinucidae) in North Central Province, Sri Lanka, Check List 13(5):1-4 pp.
Nutritional Composition and Trace Metals Accumulation of Edible Sea Urchin (Stomopneustes variolaris) in Selected areas of Sri Lanka [2014]
The sea urchins are very important marine creatures in the world and widely distributed in all seas from the Arctic to Antarctic regions. The shell and gonads of sea urchins with an economical value. They harvested for their gonads, which are a highly prized delicacy in some parts of Asia, Mediterranean and the Caribbean countries and worldwide. Gonads of a sea urchin have mainly consisted of a higher number of eggs (roe/gonads) which have high nutritional value than other seafood with organic and inorganic components and gonads are consisting of main water, protein, lipid, carbohydrate, fatty acids, vitamins and minerals. This research is done to identify the common edible species of sea urchin in selected areas, to assess the nutritional analysis of identified common species' gonads and to assess trace metals accumulation. Sampling was done from Mount- lavinia (n=43), Beruwala (n=96) and Tangalle (n=54) reefs and the study were conducted from May 2014 to October 2014 after conducting a preliminary survey around Sri Lankan sea (Indian Ocean). Sea urchins (Stomopneustes variolaris) were hand collected.
This study reveals that the sea urchins gonads nutritionally rich seafood and can be used as bioindicator (by race metal assessment) to get an idea about the ocean environment where they live.
De Zoysa, H.K.S., Jinadasa B.K.K.K., Edirisinghe, E.M.R.K.B & Jayasinghe, G.D.T.M. (2018). The association of test diameter and gonad weight with some toxic trace metals level in black sea urchin (Stomopneustes variolaris), Agriculture & Food Security, 7(58): 1-12pp.
De Zoysa, H.K.S., Jinadasa B.K.K.K., Edirisinghe, E.M.R.K.B. & Jayasinghe, G.D.T.M. (2017). Length-weight relationship of black sea urchin (Stomopneustes variolaris) in Sri Lanka, International Journal of Aquatic Biology (IJAB). 5 (6): 408-412pp.
Jinadasa B.K.K.K., De Zoysa, H.K.S., Jayasinghe, G.D.T.M. & Edirisinghe, E.M.R.K.B. (2016). Determination of the biometrical parameters, biochemical composition and essential trace metals of edible sea urchin (Stomopneustes variolaris) in Sri Lanka, Cogent Food & Agriculture. 2 (1):1-12pp.
De Zoysa, H.K.S., Jinadasa B.K.K.K., Jayasinghe, G.D.T.M. & Edirisinghe, E.M.R.K.B. (2015). Proximate Analysis and Fatty acids Profile of Edible Sea Urchin (Stomopneustes variolaris) in Sri Lanka, Extended abstract, NARA Scientific Sessions – 2015, 101-104 pp.
De Zoysa, H.K.S., Jinadasa B.K.K.K. & Edirisinghe, E.M.R.K.B. (2015). Fatty acids and Trace metals composition of Stomopneustes variolaris (Class: Echinoidea) in Sri Lanka. Proceedings of the International Journal of Food Science and Technology Conference (IJFST) 50th Celebration Conference. Lincoln, New Zealand