First Chromosome Characterization of the Indian Giant Flying Squirrel (<i>Petaurista philippensis</i>) and Lesser Giant Flying Squirrel (<i>Petaurista elegans</i>)

Abstract

We report the first chromosome analysis of the Indian giant flying squirrel (Petaurista philippensis) and lesser giant flying squirrel (P. elegans) from Northeast of Thailand. Blood samples were taken from one female squirrel. After standard whole blood lymphocytes had been cultured at 37°C for 72 h in the presence of colchicine, metaphase spreads were performed on microscopic slides and air-dried. Giemsa’s staining, GTG-banding, high resolutions GTG-banding, and CBG-banding techniques were used to stain chromosomes. The results showed that the diploid chromosome number of P. philippensis and P. elegans were 2n=38 and the fundamental numbers (NF) were 76 in both species. The chromosomes presences of metacentric and submetacentric chromosomes were 12–26 and 8–28, respectively. The largest submetacentric chromosome pair 1 showed clearly observable difference size (heteromorphic, 1a1b) in both species. GTG-banding and high-resolution GTG-banding techniques showed that number of bands of P. philippensis was 127 and 166, respectively. From the CBG-banding technique of P. philippensis showed C-positive (dark band) on the centromere of all chromosomes. Moreover, we also found dark bands on telomere of the short arm of chromosome pairs 1a, 4, 6, 7 and 9. In addition, the long arm of chromosome pair 17 showed clearly observable interstitial nucleolar organizer regions (NORs). This is the first report on polymorphism of NORs in P. elegans. The result showed that a heteromorphic had a different size of NORs of chromosome pair 17 (17a17b). The karyotype formulae could be deduced as: