title: Length variation and sequence divergence in mitochondrial control region of Schizothoracine (Teleostei: Cyperinidae) species.
abstract: Schizothoracine fish commonly called snow trouts inhibit the entire network of snow and spring fed cool waters of Kashmir, India. Over 10 species reported earlier, only five species have been found, these include Schizothorax niger, Schizothorax esocinus, Schizothorax plagiostomus, Schizothorax curvifrons and Schizothorax labiatus. The relationship between these species is contradicting. To understand the evolutionary relation of these species, we examined the sequence information of mitochondrial D-loop of 25 individuals representing five species. Sequence alignment showed D-loop region highly variable and length variation was observed in di-nucleotide (TA)n microsatellite between and within species. Interestingly, all these species have (TA)n microsatellite not associated with longer tandem repeats at the 3' end of the mitochondrial control region and do not show heteroplasmy. Our analysis also indicates the presence of four conserved sequence blocks (CSB), CSB-D, CSB-1, CSB-II and CSB-III, four (Termination Associated Sequence) TAS motifs and 15bp pyrimidine block within the mitochondrial control region, that are highly conserved within genus Schizothorax when compared with other species. The phylogenetic analysis carried by Maximum likelihood (ML), Neighbor Joining (NJ) and Bayesian inference (BI) generated almost identical results. The resultant BI tree showed a close genetic relationship of all the five species and supports two distinct grouping of S. esocinus species. Besides the species relation, the presence of length variation in tandem repeats is attributed to differences in predicting the stability of secondary structures. The role of CSBs and TASs, reported so far as main regulatory signals, would explain the conservation of these elements in evolution.
authors.affiliation: a Division of Biotechnology, Faculty of Veterinary Sciences and Animal Husbandry , Shuhama, Sher-e-Kashmir University of Agricultural Sciences and Technology , Kashmir , India and.
authors.forename: Mudasir Ahmad
authors.initials: MA
authors.lastname: Syed
authors.affiliation: b Faculty of Fisheries , Rangil, Sher-e-Kashmir University of Agricultural Sciences and Technology - Kashmir , Shuhama Srinagar , India.
authors.forename: Farooz Ahmad
authors.initials: FA
authors.lastname: Bhat
authors.affiliation: b Faculty of Fisheries , Rangil, Sher-e-Kashmir University of Agricultural Sciences and Technology - Kashmir , Shuhama Srinagar , India.
authors.forename: Masood-ul Hassan
authors.initials: MU
authors.lastname: Balkhi
authors.affiliation: b Faculty of Fisheries , Rangil, Sher-e-Kashmir University of Agricultural Sciences and Technology - Kashmir , Shuhama Srinagar , India.
authors.forename: Bilal Ahmad
authors.initials: BA
authors.lastname: Bhat
mesh_terms: D000818:Animals; D017124:Conserved Sequence; D003530:Cyprinidae / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D049810:Genetic Speciation; D018895:Microsatellite Repeats; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012045:Regulatory Sequences, Nucleic Acid
chemical_list: D004272:DNA, Mitochondrial
keywords: CSB; D-loop; Schizothoracine fishes; TAS; length variation; microsatellites; species variation