Showing papers in "Vidyodaya Journal of Science in 2013"

Occurrence of heterotrophic bacteria causing lysis of M. aeruginosa in Beira Lake, Sri Lanka

Abstract: Field and the laboratory studies were carried out to ascertain the potential impact of algicidal bacteria on Microcyctis aeruginosa from June 2005 to March 2007 in Beira Lake, Sri Lanka. M. aeruginosa, and M. wesenbergii quantitatively dominated in most sampling dates and constituted>75% of the phytoplankton cell densities when the bloom reached to its peaks. Densities of algicidal bacteria were relatively high with large fluctuations between 2.3x10 2 PFU ml -1 to 0.3x10 2 PFU ml -1 . Three algicidal bacteria species were isolated from the lake and identified as Alcaligenes denitrificans, A. xyosoxydans , and Flavobacterium marinotypicum . The algicidal effect of the bacterium was studied and the results suggest that the bacteria did not release extracellular products inhibitory to M . aeruginosa, and that the bacteria killed the algae by direct contact. In the field, rapid decline of Microcystis bloom was detected when algicidal bacteria were increased. In the laboratory, when the bacterium were inoculated at low densities (10 4 cells ml -1 ) together with Microcystis, the bacterium proliferated to 107 cells ml -1 and caused Microcystis cell lysis. Thus, the result of the present study strongly suggests that algicidal bacteria degrade M. aeruginosa bloom in natural freshwater environments. Vidyodaya Journal of Science Vol.16 2011

Limnology project at Mahaweli reservoirs:I. some physical properties of Kotmale, Victoria and Randenigala rservoirs

Abstract: The Physical properties of Kotmale, Victoria and Randenigala reservoirswere studied since 1987 upto now and this paper presents the data obtained during1987. The transparency values changed with the reservoir and the season. Thehighest frequency percentage of Secchi depth observed at each reservoir were.Victoria 1.21-1.61m, Randenigala 2.51-3. Olm and Kotmale 2.10-2.30m, indicatinghighest values at Randenigala and lowest values at Victoria. Accordingly themean euphotic limits were 5.00m at Victoria, 6.25m at Randenigaia and 5.lOmat Kotmale. The highest differences in temperature gradients were observedfrom surface to about 25m depths in all three reservoirs, in the deeper layers thetemperature gradient is distinctly low. The highest conductivity values wereobserved closer to the dams of all three reservoirs indicating the accumulation ofdissolved ions towards the dams. Range of 30-87pslcm at Kotmale, 85-139pslcm at Victoria and 110-188 pslcm at Randenigala. The highest values wererecordedfrom Randenigala. The highest conductivity values were correlated withthe water rentenion levels of the reservoirs. Fluctuations in pH values with theseasons follow a similar pattern in all three reservoirs. The mean pH values ofthe three reservoirs were in between 6.0 and 8.7. In all three reservoirs, the pHgradient was higher above 10m depth whereas below this depth it remained moreor less constant. The high dissolved Oxygen concentrations were closely linked with theeuphotic zones of the three reservoirs. The mean Oxygen concentration calculatedduring 1987 investigation period from surface to 5m depth were 4.75-7.50mg]; at Kotmale, 4.70-6.60 mgjl at Victoria and 4.70-6.65 mgfl at Randenigalareservoirs. Dissolved concentrations were very low below the depth of 20min all three reservoirs. However there was no evidencefor the presence of deoxygenated layers in all three reservoirs.

Fat contents and fatty acid profiles of Indian Scad

Abstract: Indian Scad ( Decapterus russelli , Sinhala:Linna) is one of the less expensive fish varieties in the Sri Lankan market. Total fat contents in white muscle, red muscle and skin; and fatty acid composition in white muscle of the Indian Scad were evaluated. The total fat content was relatively high in the skin (3.64%) and red muscle (3.17%) while the white muscle contained low amount (0.65%). Fatty acid profiles of white muscle showed 32.66% saturated fatty acid (SFA), 16.07% monounsaturated fatty acids (MUFA) and 39.38% polyunsaturated fatty acids (PUFA). Among SFA, those occurring in the highest proportions were palmitic acid (C16:0, 18.36%) and stearic acid (C18:0. 12.21%). Oleic acid (C18:1 n -9, 10.61%) and palmotoleic acid (C16:1 n -7, 3.91%) were the main MUFAs. Eicosapentaenoic acid (EPA, C20:5 n-3, 8.83%) and docosahexaenoic acid (DHA, C22:6 n-3, 19.76%) were the main PUFAs. The PUFA/SFA ratio was 1.21 and n-6/n-3 ratio was 0.13. Sum of EPA+DHA was 28.59%. Therefore it can be concluded that although the fat content is low the nutritional value of the fat contained in the white muscle of Indian Scad is high. Vidyodaya Journal of Science Vol.16 2011

Interrelationships among the Species of the Genus Puntius (Teleostei, Cyprinidae) as Indicated by the Meristic and Morphological Characters

Abstract: The studies of two morphological and fifteen meristic characters of twelvespecies of Puntius showed that the most successful characters in separating'species were the counts of gill rakers, lateral line scales, vertebrae and pectoralrays. The other characters are less successful. The number of spines andrays of anal and pelvic fins are constant in the genus. Based on the 17 charactersstudied the twelve species of Puntius fall into three clusters: one containing'five species, the other containing two species and the third cluster with five':species. The species of the first two clusters were associated with higher meris-, tic characters, presence of barbels and complete lateral line. The species ofthe third cluster were associated with low meristic features and they werewithout barbels with the exception of one species with two barbels. Fourspecies of the third cluster contained with incomplete lateral line whilethe other one had a complete lateral line.

Free radical Scavenging Activity and Phenolic content of decoctions of some medicinal plants

Abstract: Free radicals are normally generated in substantial amounts in the body; excessive amounts cause oxidative damage through chain reactions forming disorders like diabetes mellitus, cardiovascular and pulmonary diseases. In diabetic conditions, a non enzymatic reaction occurs with proteins and reducing sugars forming glycated protein named Amadori products. Further rearrangement, oxidation and reduction of Amadori products leads to form Advanced Glycated End products which causing spontaneous damage to proteins in physiological system leading various complications like Nephropathy, Neuropathy ,Retinopathy and this process accompanying the formation of free radicals. In this process oxidation plays an important role to form Advanced Glycated End Products. Therefore antioxidants are highly important in prevention or slowing the glycation reaction. Humans have evolved a complex antioxidant system, but this may not be sufficient to maintain optimal cellular functions in diabetic conditions. Medicinal plants usually contain different phenolic compounds having antioxidant properties. Therefore, a study was carried out to examine the in vitro free radical scavenging activity and total phenolic content of the decoctions of plants, Cassia auriculata (Ranawara, flower) Phyllanthus emblica (Nelli, fruit) and Scoparia dulcis (Walkottamalli, whole plant) which are used in the treatment for diabetics. Three fresh samples from each plant collected from different areas where they are grown and commercial dried sample from the traditional market was selected to prepare the decoctions and compared phenolic contents and antioxidant activity. The total phenolic content of each extract was determined using Folin-Ciocalteu reagent and evaluation of free radical scavenging activity was assessed using DPPH assay and ABTS assay. Decoctions of the commercial samples of P. emblica showed the highest total phenolic content as 625 mgGAE/g and C auriculata and S dulcis showed 459 and 131 mgGAE/g respectively. Samples dried under laboratory conditions of C.auriculata had total phenolic content from 226 – 287 mgGAE/g, P.emblica from 479 -517 mgGAE/g and S dulcis from 167 – 186 mgGAE/g. The highest DPPH antioxidant activity showed the commercial sample of P. emblica as 27 μg/ml and other samples dried under laboratory conditions were in the range of 41 – 49 μg/ml. No significant difference between the DPPH activity of C. auriculata commercial sample and other samples dried in the dehydrator and were in the range of 248 -309 μg/ml while S. dulcis all the samples showed DPPH antioxidant activity from 437 – 540 μg/ml. The reference standard, Butylated Hydroxy Toluene showed 20 μg/ml. ABTS antioxidant activity was high in all commercial samples of C.auriculata, P.emblica and S. dulcis and were as 648,625 and 615 mmol/g while other samples dried using the dehydrator showed 313 – 536 mmol/g,479 -517 mmol/g and 549-550 mmol/g respectively. Key words: Antioxidant properties, Glycation, Diabetes, DPPH assay, ABTS assay

Limnology project at Mahaweli reservoirs:II A limnological study at Kotmale, Victoria and Randenigala rservoirs

Abstract: The objective of this study was to collect basic data to ascertain statusof Kotrnale, Victoria and Randenigala reservoirs and to understand the trophicevolution of the reservoirs. The transparency values changed with the reservoirs.The highest frequency percentage of secchi depth observed at eachreservoir are; Victoria 1.21--1.6Im, Randenigala 2.51-3.0Im and Kotmale2.10-2.30 indicatin.g highest value at Randenigala and the lowest value atVictoria. All three reservoirs are thermally stratified and the highest differencesin temperature gradients were observed from surface to about 25m depth.In the deeper layers the temperature gradient is distin.ctly low. The highestconductivity values were observed closer to the dams of the three reservoirsindicating accumulation of dissolved ions towards the dams. In all threereservoirs the pH gradient was higher at the surface compared to the valuesbellow 10m depths. The high dissolved Oxygen concentrations are closelylinked with the euphotic zones. Oxygen concentrations were markedly lowbelow the depth of 20m. However there is no completely deoxygenatedlayers at the bottom of the reservoirs. Data on chemical substances also proves the development of a strongchemocline below 20m depth level. Water hardness values are high whenwater retention levels of the reservoirs are low. High levels of HydrogenSulfide concentrations have been observed at the bottom layers ofRandenigala reservoir from time to time. Sulfide concentration increasedwith the increasing depth of the reservoirs. The range of Nitriteconcentrations recorded for Victoria is 0.005-D.l ppm and for RandenigalaO.01-D.08 ppm. Ammonia was recorded only in deeper layersbelow the 45m level at Randenigala. The zooplankton community of the three reservoirs consists of Copepods,Rotifers and Cladocerans. The phytoplankton community of the three reservoirs consist mainly ofgreen and blue green algae.

Effect of carbachol on fertility of male rats when administered locally to epididymis

Abstract: This study examines the effect of carbachol, a potent cholinoceptor agonist drug, on fertility of male rats, when administered to epididymis using stlastic formulations, in the form of rods. 10% and 25% carbachol rods were found to be toxic, and resulted in death within 25 min. On the other hand, 5% rods were tolerable. These rods significantly reduced sperm numbers both in the cauda epididymis and ejaculate but failed to Impair fertility. Libido (sexual desire) remained essentially unaltered. In organ bath experiments, carbachol induced rhythmic contrations in isolated vasa deferentia and cauda epididymal tubules in e ' dose-related manner. Short running head: carbachol and fertility of male rats Key words: carbachol, silastic rods, epididymis fertility oligozoospermia, cholinomimetics