Chromosome mechanisms of sex determination, G- and C-band patterns and nucleolus organizer regions in Tropidurus torquatus (Sauria, Iguanidae)

Abstract

The mitotic and meiotic chromosomes of two groups of the iguanid lizard Tropidurus torquatus were studied after conventional staining, G-and C-banding and silver staining of nucleolar-organizer regions. Karyotypic variations involving the microchromosomes were observed in both groups and are, probably, related to the mechanisms of sex determination of the X ~X2Y/X ~X IX2X2 type in the one group, and of the XY/XX type in the other.

Chromosomal diversification in the gekkonid Tarentola mauritanica (Reptilia, Gekkonidae)

“…The differences in the tip length of these chromosomes might be due to different levels of amplification of the satellite-DNA sequences contained in that heterochromatin, as it has been suggested for similar polymorphisms of various species, e.g. the insect Caledia captiva (Shaw et al, 1976), the iguanid Tropidurus torquatus (Kasahara et al, 1983), and several species of Thomomys (Patton & Sherwood, 1982). However, heterochromatin would not seem to be directly responsible for the varying number of biarmed elements in the last five pairs of homologs.…”

Comparative Cytogenetic Studies of Eleven Species of the Tropidums Torquatus Group (Sauria, Tropiduridae), with Banding Patterns

“…All the specimens were deposited in the Museu de Zoologia, Universidade de Slo Paulo (MZUSP). Part of the present sample was referred previously in KASAHARA et al (1983KASAHARA et al ( , 1987aKASAHARA et al ( , 1988, RODRIGUES et al (1988), YONENAGA-YAS- SUDA et al (1988), andPELLEGRINO et al (1994).…”

“…Later, cytogenetic analyses of two species assigned to the torquatus group, using banding techniques, showed some minor chromosome differences as well as distinct mechanisms of sex-determination ( KASAHARA et al 1983). Additionally, intraspecific geographical variation was revealed for some species as different populations were karyotyped ( KASAHARA et al 1987a;KASAHARA et al 1988).…”

High-resolution RBG-banding pattern in the genus <i>Tropidurus </i>(Sauria, Iguanidae)

“…This group is characterized by the presence of keeled and imbricate dorsal scales and the absence of a mid-dorsal crest. The species belonging to this genus arc currently the subject of exhaustive cytogenetic investigations (Kasahara et al, 1983;Kasahara et al, 1987a, b;Rodrigues etal., 1988). In some species, such as T. hispidus (Kasahara et al, 1987a), T. amathiles, and T. divaricatus, longitudinal chromosome differentiation was obtain ed after in vivo injection of BrdU or FudR.…”