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අරුම පුදුම ගස්වැල්
(Colombo : National Science Council ; NA Colleciton, 2015-01) Ranwala, S.M.W.
National Science and Technology Awards 2006
(Colombo : National Science Foundation ; NA Collection, 2006) National Science Foundation of Sri Lanka
Submergence tolerance and tolerance mechanism: A study on traditional and improved rice genotypes at the seedling stage under complete submergence stress in Sri Lanka
(National Science Foundation: Colombo, 2023-10-12) Shyamalee, H.A.P.A.; Ranawake, A.L.
Submergence-tolerant genotypes in rice are essential for flood-prone lands, and recent studies have focused on dissecting tolerance mechanisms considering morphological and physiological changes in the plants upon submergence. Thirty improved rice varieties and sixty-two traditional rice accessions were screened for submergence tolerance under complete 9-day and 14-day submergence stress at the two-week-old seedling stage. The submergence tolerance level of each rice genotype was evaluated according to IRRI guidelines based on survival rates. Accordingly, rice genotypes were categorized into four groups: tolerant, moderately tolerant, moderately susceptible, and highly susceptible. Two Mawee accessions (3704, 3618) were submergence tolerant at 14-day submergence stress. The traditional rice accessions Ratawee3466, Mawee (8552, 4145), and Heenati4935 and improved rice varieties Bw400 were moderately submergence tolerant at 14-day submergence stress. Survival rates of the rice genotypes, their initial plant height, and shoot elongation at 9-day and 14-day submergence stress showed that seedling elongation (escape strategy) or reduction of elongation compared to control plants (quiescence strategy) under submergence stress cannot be used as phenotypic markers for selecting rice genotypes for submergence tolerance in rice. Further, the escape strategy or the quiescence strategy was not unique to the genotype, and the survival strategy of some rice genotypes changed with prolonged submergence stress. The escape strategy tended to be an SOS (Save Our Souls) strategy under prolonged submergence stress from 9 days to 14 days. No correlations between initial plant height and survival rate or survival rate and the height gain or reduction at 9-day and 14-day submergence stress showed that the submergence tolerance mechanism in rice was genotype-specific. The submergence-tolerant and moderately tolerant rice genotypes could be further investigated in future studies.
Pulsed-field gel electrophoresis typing and molecular characterization of Listeria monocytogenes isolates in raw milk samples from Polonnaruwa District, Sri Lanka
(National Science Foundation: Colombo, 2023-10-12) Wijendra, W.A.S.; Kaushalya, A.G.G.; Kuruppuarachchi, K.G.R.; Harshani, H.B.C.; Fonseka, W.A.S.I.; Ramesh, R.
Listeria monocytogenes is an important food borne human pathogen associated with severe diseases in humans and animals. Human infection is associated with high mortality rates. Our previous studies done in 2012 on milk and milk products revealed 4b as the dominant serotype followed by 1/2a, 1/2b and 1/2c. Listeria monocytogenes is an important food borne human pathogen associated with severe diseases in humans and animals. Human infection is associated with high mortality rates. Our previous studies done in 2012 on milk and milk products revealed 4b as the dominant serotype followed by 1/2a, 1/2b and 1/2c. Therefore, this study was conducted to determine the sources of contamination and to identify the strain differences (pulsotypes) by pulsed-field gel electrophoresis (PFGE) typing and serotype profiles of L. monocytogenes isolates from farm collected raw milk samples from randomly identified locations in Grama Niladhari divisions of the Polonnaruwa district, Sri Lanka. Eighty isolates obtained from raw milk samples were confirmed as L. monocytogenes by Polymerase Chain Reaction, belonging to serotypes 4b, 1/2a, 1/2b and 1/2c. The strains were identified by PFGE. PFGE analysis digested with AscI and ApaI enzymes revealed different banding patterns. All the pulsotypes were found to be serotype 4b. The sub typing indicated the diversity of the Listeria species. The presence of serotypes 1/2a, 1⁄2b, 1/2c, and 4b in raw milk is a public health concern, as these serotypes are frequently associated with foodborne outbreaks and sporadic cases of human listeriosis. In our study, PFGE analysis allowed discrimination among isolates of the same serogroup. Further PFGE analysis showed heterogeneity among isolates recovered from both same sampling areas and different areas.
Single and combined effect of fluoride and hardness of drinking water on nephrotoxicity: in-vivo study using Wistar rats as an animal model
(National Science Foundation: Colombo, 2023-10-12) Dilrukshi, K.T.; Beneragama, D.H.; Suresh, T.S.; Wanigasuriya, J.K.P.; Manage, P.M.
Drinking water in areas with a high prevalence of chronic kidney disease of unknown aetiology (CKDu) in Sri Lanka is known to have high concentrations of fluoride and hardness. The present study evaluated the individual and combined effects of water hardness and fluoride on potential nephrotoxicity, using Wistar rats as an animal model. Thirty-five Wistar rats were randomly assigned into five groups (n=7). Test groups F, H, RL, and RH were given de-ionized water containing 1.5 mg/L fluoride, 200 mg/L hardness, 1.5:200 mg/L fluoride: hardness, and 5:800 mg/L fluoride: hardness respectively, while control group C was given de-ionized water. Body weight and daily water consumption were measured. Serum creatinine, urine creatinine, and urinary biomarker KIM-1 were analyzed. Histopathological changes in the kidneys were observed. There were no significant differences in body weights (p>0.05) while daily water consumption was reduced significantly in the test groups RL and RH (p<0.05). A significant increment in serum creatinine in the RL and RH groups (p<0.05), and a significant reduction in urine creatinine in the F, H, RL and RH groups (p<0.05), were recorded compared to the control. However, the highest magnitude of the effect on serum creatinine and urine creatinine was recorded in the RL group. Significant increment in KIM-1 levels were recorded in the RH group (p<0.05) while the RH group indicated a more rapid increment from the 28th day. When considering histopathology, renal tubular changes were observed in the test groups. The individual and combined effects of water hardness and fluoride may contribute to the aetiology of CKDu in Sri Lanka.