Karyological Analysis of Lesser Bamboo Rat, Cannomys badius (Rodentia, Rhizomyinae) by Classical and Molecular Cytogenetic Techniques

Abstract

The lesser bamboo rat (Cannomys badius) from Phetchabun Province, Thailand was cytogenetically studied by classical and molecular cytogenetic techniques. Blood samples were taken from lesser bamboo rat and then subjected to standard whole blood T-Lymphocyte culture. The chromosomes were harvested by colchicine-hypotonic-fixation-air drying technique. Conventional, Ag-NOR banding and fluorescence in situ hybridization (FISH) techniques were used to apply on the metaphase chromosomes. The results showed that the karyotype of lesser bamboo rat had the diploid chromosome number of 2n=50 and the fundamental number (NF) of 94. The autosomes consisting of 12 large acrocentric, two medium submetacentric, 10 medium acrocentric, four small metacentric, six small submetacentric, eight small acrocentric and six small telocentric chromosomes. The X chromosome is the largest metacentric chromosome. The nucleolar organizer regions (NORs) were observed in the short arms of chromosome pairs 7, 10 and 17 for the first time. In addition, the molecular probe, microsatellite d(CA)₁₅ was revealed the hybridization signal detected at subcentromeric region in the long arms of chromosomes pair 13. The obtained results suggested that NORs and microsatellite d(CA)₁₅ probe can be used as specific markers for this species. Our results are also fulfilled the basic cytogenetic knowledge for C. badius.