Evaluation of carboxylated poly-l-lysine for cryopreservation of Labeo rohita sperm.

Carboxylated poly-l-lysine (CPLL) is an anti-freeze agent having pronounced non-permeating yet membrane stabilizing cryoprotective capabilities. The objective was to evaluate the CPLL supplementation in extender in terms of post-thaw quality (sperm), total anti-oxidant activity (milt) and fertilization potential of cryopreserved Labeo rohita sperm. For this purpose, male brood fish reared at a fish seed hatchery, Rawal Town Islamabad, Pakistan were captured from different rearing ponds and acclimatized in hatchery ponds for 6 h. The brooder was injected with Ovaprim (0.2 mL/kg), and milt was collected after 8 h in cooled sterilized falcon tubes, maintained at 4°C and evaluated for sperm motility. The milt collected from three brooders (n = 3) was diluted in extenders viz., modified Kurokura-2 extender having 10% methanol (control); experimental extenders with CPLL supplementation at the rate of 0.5%, 1% and 1.5%. Diluted milt was filled in 0.5 mL straws, exposed to liquid nitrogen vapours and cryopreserved. Cryopreserved milt was thawed at 25°C and assessed for post-thaw sperm quality. Sperm motility, motility duration, viability, total anti-oxidant capacity and DNA integrity was significantly higher (p < 0.05) in the extender having 1.5% CPLL than control. To evaluate the fertilization rates, male and female brooders were injected with Ovaprim at 0.2 mL/Kg and 0.5 mL/Kg body weight respectively. Fresh eggs and milt were collected through abdominal stripping. Batches of 10 g of eggs from each female (n = 2) were fertilized with one straw, each from frozen sperm with KE + methanol (control), KE + methanol + 1.5% CPLL and 50 µL fresh milt (negative control). After 1.5 h of fertilization, eggs were collected from all jars and a total of 200 eggs were counted. The fertilized eggs appeared clear and transparent while unfertilized eggs looked opaque with disintegrated nuclei. Sperm fertilization rate (%) was higher (p < 0.05) in extender KE + methanol + 1.5% CPLL (78.7 ± 0.5) compared to control (KE + methanol) (52.0 ± 0.4) however, it was lower compared to that of negative control, the fresh milt (85.2 ± 0.6). In conclusion, supplementation of carboxylated poly-l-lysine (1.5%) to modified Kurokura-2 extender having 10% methanol improves post-thaw motility, motility duration, viability, DNA integrity, anti-oxidant capacity (milt) and fertilizing ability of cryopreserved L. rohita sperm.

Seasonal variation in non-point source heavy metal pollution in Satpara Lake and its toxicity in trout fish.

Heavy metal contamination in surface water is widespread throughout the world as a result of numerous anthropogenic activities and geo-genic mechanisms. This contamination is also affecting aquatic life, as fish have the potential to acquire heavy metals in their tissues making them vulnerable. Worldwide lakes are an important source of water for the inhabitants of the area. So, in the present study, we have focused on the Satpara Lake to check the extent of heavy metal pollution and their accumulation in fish to provide baseline data for metal pollution management. Samples were collected from three locations (inflow, center, and outflow sites) during two seasons (summer and winter). Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to analyze heavy metals concentration. Among the metals, Cd, Pb, As, and Fe revealed relatively higher concentrations. The highest concentration of heavy metal found in water and fish was of Cd, i.e., 8.87 mg L-1 and 18.19 mg L-1 in summer season, respectively. Arsenic concentration was also higher than the permissible limits in both water (0.76) and fish (1.17 mg L-1). The water quality assessment showed that in the summer season, the HPI (heavy metal pollution index) value 253.01 was more than 100, indicating the bad quality of water for drinking purposes. However, the HPI value 35.72 was less than 100 in winter. Toxicity hazard calculation of fish in summer seasons gives Hi values greater than 10.0, indicating the acute effect on human health as compared to winter.