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Biomedical subjects

S K Atreja

Publications and source records attributed to S K Atreja.

9 recordsLinked to original sources
PubMed2004

Phospholipase A2 activation by hydrogen peroxide during in vitro capacitation of buffalo spermatozoa.

Progressively motile, washed buffalo spermatozoa (50 x 10(6) cells in 0.5 ml) were in vitro capacitated in HEPES containing Bovine Gamete Medium 3 (BGM3) in presence of heparin (10 microg/ml), and different concentrations of hydrogen peroxide (10 to 100 microM). Spermatozoa (60%) were capacitated in presence of heparin compared to 56% in presence of 25 microM H2O2 (optimally found suitable for capacitation). The extent of capacitation was measured in terms of acrosome reaction (AR) induced by lysophosphatidyl choline (100 microg/ml). The acrosome reacted cells were counted after triple staining. Catalase (100 microg/ml) significantly reduced the sperm capacitation to 16-18% when added with H2O2, or alone in the capacitation medium. Phospholipase A2 activity of spermatozoa increased linearly up to 50 microM H2O2 concentration included in the assay system. Moreover, significant increase in phospholipase A2 activity was observed after capacitation by both, the heparin and 25 microM H2O2. The activity was always higher in acrosome reacted cells.

Acrosome Reaction↗
PubMed1991

Phosphoinositide specific phospholipase C activity of goat spermatozoa in transit from the caput to the cauda epididymis.

Goat sperm lysate from cauda epididymis was incubated in the presence of [14C]phosphatidyl-choline, -ethanolamine, -inositol and diphosphatidyl-glycerol. The release of [14C]diacylglycerol from only phosphatidyl inositol confirmed the presence of phosphatidyl inositol specific phospholipase C. The enzyme activity was linear up to 1 hr of incubation at a sperm concentration of 1-10 x 10(9). It had pH optimum of 7.5 in a broad range of pH activity profile (pH 6-9). Maximum activity was observed at 8 mM calcium ion concentration. EDTA and EGTA (5 mM) did not inhibit the activity completely. A comparative study on spermatozoa and fluid from caput, corpus and cauda epididymis revealed 6.5-fold increase of activity in spermatozoa and a 4-fold decrease in case of fluid during the epididymal transit. However, the total protein content remained unchanged in fluid and decreased up to the extent of 2.4-fold in spermatozoa during this process. Thirty five percent of the caudal sperm activity was soluble and the rest was associated with head (44%), mid-piece (10%) and tail (10%).

Animals↗
PubMed1989

In vitro capacitation of goat spermatozoa.

Goat epididymal and ejaculated spermatozoa were incubated in Krebs-Ringer bicarbonate buffer containing pyruvate and lactate as energy source. A 3 hr incubation for epididymal and 4 hr for ejaculated spermatozoa was required for the capacitation and acrosome reaction to take place. Calcium is an essential requirement which was needed for motility maintenance/activation and for the initiation of acrosome reaction. A 2-fold increase in cAMP content was measured over 3 hr period of incubation of goat epididymal spermatozoa which was not seen when calcium ions were either omitted or chelated with EGTA. There is thus a definite involvement of Ca2+ ions and cAMP in capacitation and acrosome reaction of goat spermatozoa.

Acrosome↗
PubMed1985

Phospholipase and lysophospholipase activities of goat spermatozoa in transit from the caput to the cauda epididymidis.

Phospholipase and lysophospholipase activities were assayed in goat epididymal spermatozoa. Lysophospholipase was 10 times more active than phospholipase, and both enzymes decreased in activity substantially in the transit of spermatozoa from the caput to the cauda epididymidis. A comparative study revealed that phosphatidyl-ethanolamine, -choline and -inositol and phosphatidic acid were hydrolysed by goat sperm phospholipase. Hydrolysis of phosphatidylethanolamine/phosphatidylcholine revealed the end products to be glycerophosphoethanolamine/choline but neither diglycerides nor lysophosphatidylethanolamine/lysophosphatidylcholine were detected.

Animals↗
PubMed1978

Uptake of glusose-C14 and fructose-C14 by buffalo spermatozoa in extenders during cold storage.

Buffalo spermatozoa exhibit insignificant uptake of glucose-C14 and fructose-C14 when semen samples were preserved in cold for 96 h in 2 extenders. Incorporation of C14 in spermatozoa, TCA precipitable proteins and soluble sugar phosphates was either equal or less in semen samples preserved in cold. CAW appeared to be a better extender than SKMEY as revealed by sugar uptake in cold.

Animals↗