Volume 05 No. 01 July 1994

The In vitro Effect of Exogenous Melatonin on Motility of Human Spermatozoa

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The In vitro Effect of Exogenous Melatonin on Motility of Human Spermatozoa Ratnasooriya, W.D.; Jayawardena, P.A.H.L.; Perera, P.A.C.T. Melatonin, a hormone secreted by the pineal gland is preesnt in the semen and melatonin binding sites have been demonstrated on the plasma membrane of sperm. These observations suggest a possible modulatory role of melatonin on sperm function. The aim of this study was to investigate the effects of melatonin on motility of human sperm in vitro. The concentration tested were 75, 150, 300, 450 and 900 pg mL-1 and the period of investigation was 120 min. The results show that, at all concentrations tested, melatonin suppressed motility of sperm. This antimotility effect was not dose-dependent but was time-dependent ; the greatest inhibition for a particular concentration being evident at the highest time point of incubation. Melatonin was not necrospermic but was only spermiostatic. Furthermore, it did not markedly alter the functional integrity of sperm of plasma membrane as revealed from the hypoosmotic swelling test. It is suggested that the sperm antimotility effect of melatonin may be due to its membrane stabilizing actions.

Some Micronutrient and Macronutrient Contents of Some Sri Lanka Food Varieties

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Some Micronutrient and Macronutrient Contents of Some Sri Lanka Food Varieties Deraniyagala, S.A.; Mudalige, K.T.; Anula, H.M.; Jamburuthugoda, M.Y.P.R. The food tables used today in Sri Lanka contain only little data on Sri Lanka food varieties : besides they do not contain information about some of the nutritionally important minerals present in these food varieties. As a result food composition data users are dependent on a food table that is inadequate. As a remdial measure some nutritionally important minerals (Na,K,Ca,Mg, Fe, Zn, &Cu,) present in some Sri Lanka fruits, leafy vegetables, pulses and cereals; the total available carbohydrate content of cereals, pulses & fruits, the protein content of cereals & pulses and the fibre & moisture content of fruits and leafy vegetables have been determined.

Some Aspects of Biology of the Snakehead, Ophicephalus striatus Bloch in Muthurajawela, a Peaty Swamp in Sri Lanka

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Some Aspects of Biology of the Snakehead, Ophicephalus striatus Bloch in Muthurajawela, a Peaty Swamp in Sri Lanka Wijeyaratne, M.J.S. Growth, reproduction and mortality of the snakehead, Ophicephalus striatus Bloch, inhabiting the Muthurajawela swamp, a low pH environment in Sri Lanka, were studied using monthly samples collected by angling and indigenous fish traps. The asympototic standard length and growth coefficient were estimated to be 49.5 em. and 0.194 year" respectively. These figures were smaller than those estimated for this species in other regions of the country. The estimated total and natural mortality coefficients were 3.7'year-1 and 1.7 year " respectively. The exploitation ratio was 0.5 and indicates that this stock is exploited at the optimum level. The absolute fecundity of the fish ranging from 23.8 em to 29.5 cm in standard length varied from 3800 to 10800 eggs. These figures are higher than those recorded for O. striatus in other regions of Sri Lanka. The relative fecundity ranged from 19 to 38 eggs/g of body weight. The minimum size at maturity for the females and males were 19.5 em and 24.5 em respectively. The sex ratio was found to be 1 female : 3.6 males.

Similarities among Eleven Species of Cyprinids (Teleostei) as Indicated by Their Counts of Gillrakers, Meristics and Morphometry

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Similarities among Eleven Species of Cyprinids (Teleostei) as Indicated by Their Counts of Gillrakers, Meristics and Morphometry Kotalawala, A.B. The numbers of gill rakers, 12 meristic characters and 20 morphometric ratios were studied in 11 species of Sri Lankan cyprinids by using digested stained specimens and preserved specimens. The statistical analysis of characters show. d that the counts of gill rakers, vertebrae, lateral line scales, pectoral fin rays and most of the morphometric ratios made significant differences among the species studied. In the analysis of results of ANOV A tests using matrices showed that the 11 species of cyprinids fall in to 4 clusters : Danio malabaricus (Jerdon) and Chela laubuca (Hamilton - Buchanan) in cluster one, Rasbora vaterifloris (Deraniyagala) and Horadandiya athukorali (Deraniyagala) in cluster two, Rasbora daniconius (Hamilton-Buchanan), Amblypharyngodon melettinus (Valenciennes), Rasbora caveri (Hora), and Esomus danrica thermoicos (Valenciennes) in cluster three,