Study of Chromosome Morphology of Venerid Clam Paphia Textile

Abstract

In recent years, the number of cytogenetic studies on bivalves has remarkably increased. Karyotypes of mollusc species have been studied by banding techniques and fluorescence in situ hybridization (FISH), although most of them are limited to a few families, such as Mytilidae, Ostreidae, Pectinidae, Cardiidae and Veneridae. Chromosome spreads of bivalves were also used using different tissues: gonad, embryos, and adult gills. During the present study, chromosome spreads of venerid clam, P. textile were used to study the karyotypes of this clam. The study indicated that the species had 38 chromosomes with 7 metacentric, 5 submetacentric, 3 subtelocentric and 4 telocentric pairs. The Absolute length of the chromosomes ranged from 1.1 to 2.8. The Relative length ranged from 3.23 to 8.24. The Centromeric index ranged from 0 to 48.14. The Arm ratio showed a variation between 1.08 to “. Fundamental arm number for P. textile was 64. During the current study, the percentage of euchromatin observed in both the long and short arms of the chromosomes of the clam species was more compared to the heterochromatin, indicating active regions of replication and transcription. This also indicated that the phenotypic expression of genes and also the variations observed in the species were due to the euchromatin.