[01] Diana Conrad Thelagathoti, Department of Zoology, Andhra University, Visakhapatnam, Andhra Pradesh, India. [02] Manjulatha Chapara, Department of Zoology, Andhra University, Visakhapatnam, Andhra Pradesh, India.

Karyotypic and cytogenic characteristics of threadfin bream Nemipterus japonicus described from Visakhapatnam coast, India was studied by examining 200 metaphase chromosome spreads from the kidney cells of 25 healthy and 25 diseased specimens. The diploid chromosome number of this species 2n=60. The karyotype consisted of 18= metacentric (M), 6= submetacentric (Sm) and 36= subtelocentric (St) chromosomes. The chromosome formula can be represented as 2n= 18 M+ 6 Sm+ 36St. No heteromorphic sex chromosomes were cytotypically detected. In diseased fish increased sets of chromosomes was observed causing pathological changes in response to cellular stress, or in state of tumorogenesis. The present study is the first report on the karyology and in particular ploidies of this species. Thus this study is of importance in the analysis of karyotypic trends and role of polyploidy in development of tumours.

Metaphase, Chromosome, Karyotype, Nemipterus Japonicus

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