This study focused on the development of a protocol for cryopreservation of sperm of the endangered fish species, Pabda Catfish Ompok pabda. The activation of sperm motility was tested at various osmolalities of NaCl. The motility of sperm decreased with the increase of osmolality; it was completely inhibited at 319 mOsmol/kg. Toxicity of cryoprotectants to sperm was evaluated using dimethyl sulfoxide (DMSO), methanol, and ethanol at 5, 10, and 15% concentrations at an incubation time of 0–35 min. Five percent and 10% cryoprotectants produced 45–75% and 40–75% motility for the 5‐ and 10‐min incubation times, respectively. Sperm incubated with 15% cryoprotectant had less motility from the beginning of incubation. The cryoprotectant was toxic to sperm. Three extenders, Alsever's solution, egg‐yolk citrate, and urea egg‐yolk, as well as three cryoprotectants, DMSO, methanol, and ethanol, were used for the preservation of sperm. Alsever's solution with DMSO showed best performance producing highest equilibration motility (83 ± 3.3%, mean ± SE) and postthaw motility (71 ± 4.4%) followed by levels of 68 ± 1.7% and 51 ± 1.7%, respectively, with Alsever's solution plus methanol. Sperm preserved with Alsever's solution plus DMSO produced 79.33% fertilization and 42.38% hatching while fresh sperm yielded 82% fertilization and 53.49% hatching. No statistical comparisons between cryopreserved and fresh sperm were made as we did not standardize the sperm concentration for fresh and cryopreserved sperm during breeding. Fry produced from both cryopreserved and fresh sperm were reared in aquaria for 6 weeks and no significant differences for length (P = 0.452) and weight (P = 0.431) were observed between the two groups. The protocols developed through this study can be applied for conservation of endangered Pabda Catfish, and the findings of breeding and growth studies suggest it would be useful to disseminate the cryopreservation technology to commercial hatcheries.

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Characterization and variability analysis is important for the improvement of crop plant. This study aimed to evaluate the morphological and molecular variation of exotic early maturing rice (Oryza sativa L.) lines. A total of 32 exotic rice lines collected from different locations were genotyped and clustered using selected SSR markers. Based on morphological dendrogram, the lines were grouped into three clusters viz.I, II and III. Cluster I, cluster II and cluster III had 12, 11, 9 lines respectively. The results showed that the varieties were closely related belonging to the same cluster. DNA Markers namely Simple Sequence Repeats (SSR) is a useful tool for assessing genetic variations and resolving cultivar identities. Positive correlations were found between gene diversity, number of allele, the allele size range and the maximum number of repeats. Among the primers used RM147 identified more number of alleles and average PIC was 0.88. The UPGMA dendrogram based on Nei's (1972) genetic distance grouped the 32 rice lines into three major clusters. This result indicates that the line which formed grouped together, they are less diverse. A significant level of polymorphism based on morphological and molecular levels was observed. Being grouped into three clusters C1-4-11-7P-2P-1P and IR 79201-49-1-1-1 could be utilized as potential parents for the improvement of yield in early maturing rice lines.