Ashoktaru Barat

Genetic variation between four species of Indian major carps as revealed by random amplified polymorphic DNA assay

Information on the genetic structure of cultivable fish species is essential for studying molecular systematics and optimising fisheries management and fish farming. The random amplified polymorphic DNA (RAPD) assay was evaluated for studying genetic relationships and diversities in four species of Indian major carps (Family Cyprinidae). Thirty-four arbitrary primers were screened to identify species-specific RAPD markers among rohu (Labeo rohita), kalbasu (L. calbasu), catla (Catla catla) and mrigal (Cirrhinus mrigala). Distinct and highly reproducible RAPD profiles with a great degree of genetic variability were detected among species. On average, 45% of the scorable RAPD bands were specific to each species. Phylogenetic analysis demonstrated that kalbasu is the closest to rohu and the farthest from mrigal. Data are presented with regard to the applications of RAPD markers for hybrid identification, genetic diversity assessment and studying taxonomic relationships at a molecular level.

Complete mitochondrial genome organization of Tor tor (Hamilton, 1822)

Abstract The complete mitochondrial genome of Tor tor, a threatened “Mahseer” was sequenced for the first time. The mitochondrial genome size determined to be 16,554 bp in length and consisted of 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNA genes and a control region or displacement loop (D-Loop) region, resembling the typical organizational pattern of most of the teleost. The overall base composition found was A: 31.8%, T: 25%, G: 15.7% and C: 27.4%; A + T: 56.9% and G + C: 43.1%. The phylogenetic tree constructed using 11 other cyprinids’ total mtDNA datasets confirmed the location of present species among mahseers. The total sequence data could support further study in molecular systematics, species identification, evolutionary and conservation genetics.

Molecular characterization of rainbow trout, Oncorhynchus mykiss (Walbaum, 1792) stocks in India

In India, rainbow trout was introduced by British more than 100 years ago (Agarwal 2006) for recreational purposes. The fish is being cultured in both government and private farms of different coldwater states of India, mainly in Jammu and Kashmir, Himachal Pradesh, Sikkim, Arunachal Pradesh and Uttarakhand, and also in Nilgiri hills of south India for breeding and rearing purposes. In recent past, growth and production rate of this fish in various farms has been reduced. Microsatellite markers in combination with recent statistical approaches represent a useful tool for genetic characterization which ultimately supports the management of cultured stocks. These markers have been successfully used to evaluate the wild and farm stocks of rainbow trout in western Australia (Ward et al. 2003); resident and anadromus forms in the Walla Walla river (Narum et al. 2004); domesticated strains of rainbow trout in USA (Silverstein et al. 2004); strains in northern and eastern Europe (Gross et al. 2007) and three groups of different origin in north of Iran (Yousefian et al. 2012). Hence, the present study was carried out to assess the genetic variability in different stocks of rainbow trout in India using microsatellite markers.

Genetic characterization of two coldwater fishes from Kumaun Hills, Uttarakhand

Two species of fishes, Acanthocobitis botia and Barilius bendelisis, belonging to the families Cobitidae and Cyprinidae, respectively, were studied using karyotype and the cytochrome b gene. Both the species were collected from Kosi River, near Almora, Uttarakhand, India (29°37′ N, 79°40′ E). The somatic karyotypes of A. botia (2n = 50; 12m + 14sm + 10st + 14T; NF = 80) and B. bendelisis (2n = 50; 16m + 14sm + 10st + 10T; NF = 80) were described. A fragment of approximately 307 bp that corresponds to the cytochrome b region of mtDNA was also amplified by polymerase chain reaction (PCR). The mtDNA sequencing study indicated high per cent sequence divergences between the two species. Overall average percentage of nucleotide composition in A. botia was A(0.303), T(0.329), G(0.136) and C(0.232) and in B. bendelisis A(0.216), T(0.293), G(0.207) and C(0.284). Phylogenetic analysis based on the neighbor-joining (NJ) method using p-distance revealed that A. botia and B. bendelisis belonged to two different clades; this was also supported by species-specific karyotypes in the two species.