The Karyology of <i>Uraeotyphlus gansi</i>, and Its Implications for the Systematics and Evolution of Uraeotyphlidae (Amphibia: Gymnophiona)

Abstract

The gross karyotype of the uraeotyphlid caecilian Uraeotyphlus gansi is described as comprising 2n = 42 and fundamental number = 58. These are the first karyotype data for any species of malabaricus-group Uraeotyphlus, and the diploid number is the same as those ichthyophiids thus far studied and differs from the oxyurus-group Uraeotyphlus (2n = 36). These data support the recognition of two species groups within Uraeotyphlus, the monophyly of the oxyurus group, and the understanding that the ancestral diatriatan was more ichthyophiid- than uraeotyphlid-like.

Chromosomal homology of Uraeotyphlus oxyurus group of species (Amphibia, Gymnophiona, Ichthyophiidae)

“…This karyolgical description lends support to Gower and Wilkinson’s (2007) contention that it is possible to draw conclusions as to the karyological affinities between the two taxa through a comparison of the primitive uraeotyphlid karyotype with that of ichthyophiid karyotypes. The karyogrammic and morphometric data on the karyotype of Uraeotyphlus gansi and that of representative karyotype of Ichthyophis and Caudacaecilia ( Nussbaum 1991 ; Venkatachalaiah and Venu 2002 ; Matsui et al 2006 ; Venu 2008 ) lend support to the concept of closer phylogenetic affinity between the two taxa within the family ( Wilkinson et al 2011 , Venu et al 2011 ).…”

“…Until now, none of these species karyotypes were known except a publication citing a variable karyotype for the species belonging to the genus, Uraeotyphlus , Uraeotyphlus gansi . Venu et al (2011) have described the karyotype of Uraeotyphlus gansi bearing a different basic chromosomal number (2n=42) and morphology. A major attribute of Uraeotyphlus gansi karyotype is that it is similar to any of the known karyotypes of the species belonging to Ichthyophis and Caudacaecilia of the family Ichthyophiidae ( Venkatachalaiah and Venu 2002 , Matsui et al 2006 , Venu 2008 , Venu et al 2011 ).…”

“…After in vivo colchicine treatment, chromosome preparations were obtained from the liver, the gut epithelium and the testis. Cell suspensions, hypotonic treatment and fixation of cells were performed as described earlier ( Venkatachalaiah and Venu 2002 , Venu et al 2011 ). Chromosome number and standard karyotype (in respect of somatic metaphase and meiotic pachytene) morphology were determined by conventional Giemsa staining technique.…”

“… Venkatachalaiah and Venu (2002) gave a detailed karyotypic characteristic of what was then mistakenly thought to be Ichthyophis malabarensis Taylor, 1960 (2n=36, FN= 60) but which was subsequently found to be Uraeotyphlus prope interruptus of Ichthyophiidae . With this surge of interest to elucidate the phylogeny and evolution, Venu et al (2011) have presented the chromosomes of a member of the Uraeotyphlus malabaricus species group, Uraeotyphlus gansi , bearing2n=42, FN=58, highest diploid number known thus far for a member of the genus Uraeotyphlus of the family Ichthyophiidae .…”

Modelo experimental de cárie dentária como ferramenta educativa em escolares

“…O tecido dentário, nessa faixa de pH, sofre o processo de des-remineralização com participação ativa da saliva, tentando regular a perda e ganho de mineral. Após a formação da mancha branca, se o pH continuar frequentemente ácido, há colapso do esmalte formando cavidade (13)(14)(15).…”