EVALUATION OF SEMINAL PLASMA IONIC COMPOSITION DURING OFF-SEASON SPAWNING OF Cyprinus carpio (LINNAEUS, 1758) FROM MANIMUTHAR REGION OF SOUTH INDIA
Electrolytes such as Ca2+, K+, Mg2+ and Cl- in the seminal plasma modulate the osmolality of the milt which in turn triggers sperm motility in cyprinids like C. carpio whose peak spawning occurs during July to August and January to March. The concentration of these ions highly varies depending on spawning period, serving to be a suitable biomarker of sperm quality. Thus, the present study aimed at analyzing the ionic composition of seminal plasma during off-season spawning of C. carpio from Government Fish Seed Farm, Manimuthar in Southern India. This investigation would help delineating the role of different ions in sperm motility for formulating suitable extenders during its cryopreservation.
Milt was collected from proficient milters weighing 725±300 g without any contamination of urine, blood and faeces and was pooled together. The milt volume was noted in graduated vials. The collected samples were stored at 4°C immediately and transported to the laboratory. One µl of was placed on microscopic slides and activated using 10 µl tap water and the motility duration was recorded using phase contrast microscope (Nikon E360) at 200X. The milt pH was recorded using non-bleeding pH indicator strips (pH 0-14; Merck, Germany).
The seminal plasma was separated from milt by centrifugation at 10,000 g for 10 mins at room temperature and the spermatocrit value was recorded. The supernatant was stored immediately at -20°C until analysis. The ionic composition of the seminal plasma was estimated using an UV-Vis
Spectrophotometer (Perkin Elmer - Lambda 25). All glasswares used were ensured ion free. The analysis of Ca2+, Mg2+, K+ and Cl- were done using OCPC, Calmagite, Tetraphenylboron and Thiocyante methods respectively and the values are presented in Table 1.
