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The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini.

Fil: Ferro, Juan Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina

Fil: Boeris, Juan Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina. Universidad Nacional de Misiones; Argentina

The severe phenotype of human females whose karyotype includes tiny ring X chromosomes has been attributed to the inability of the small ring X chromosome to inactivate. The XIST locus is expressed only from the inactive X chromosome, resides at the putative X inactivation center, and is considered a prime player in the initiation of mammalian X dosage compensation. Using PCR, Southern blot analysis, and in situ hybridization, we have looked for the presence of the XIST locus in tiny ring X chromosomes from eight females who have multiple congenital malformations and severe mental retardation. Our studies reveal heterogeneity within this group; some rings lack the XIST locus, while others have sequences homologous to probes for XIST. However, in the latter, the locus is either not expressed or negligibly expressed, based on reverse transcription-PCR analysis. Therefore, what these tiny ring chromosomes have in common is a level of XIST transcription comparable to an active X. As XIST transcription is an indicator of X chromosome inactivity, the absence of XIST transcription strongly suggests that tiny ring X chromosomes in females with severe phenotypes are mutants in the X chromosome inactivation pathway and that the inability of these rings to inactivate is responsible for the severe phenotypes.

Populations of the diploid-tetraploid treefrogs Hyla chrysoscelis and H. versicolor can be defined by the polymorphic positions of the nucleolar organizing regions (NORs) on their chromosomes. Evidence from NOR positions and interstitial telomere sequence data shows that gene flow between H. chrysoscelis populations appears to be restricted, with contact occurring only in narrow \"hybrid\" zones. Hyla versicolor appears to have had multiple origins from H. chrysoscelis populations, and this, too, is reflected in the NOR positions. We used replication banding to determine if genetic isolation of H. chrysoscelis populations was accompanied by karyotype evolution in the populations or in contact zones. We also sought to detect karyotype alteration or replication differences associated with polyploidy in H. versicolor. Homologous chromosome pairs of all H. chrysoscelis studied displayed no differences in replication banding patterns, nor did they differ from those of H. versicolor. Although NOR positions differed between the populations studied, no disturbance of the replication banding patterns was found, indicating that structural rearrangements were not involved in creating the multiple NOR positions seen in populations of H. versicolor and H. chrysoscelis.

Chromosomes from 12 species of treefrogs were treated with trypsin and stained with Giemsa stain (G-banded). Banded karyotypes were compared within and between species. Based on this analysis, three species groups were discerned: the Pseudacris triseriata group, consisting of P. t. feriarum, P. brimleyi, P. ornata and H. crucifer; the Hyla gratiosa group, consisting of H. gratiosa, H. squirella, H. cinerea; and the Hyla chrysoscelis group, consisting of H. andersoni, H. chrysoscelis (two chromosome morphs), H. versicolor, H. avivoca and H. femoralis. These groupings generally agree with groupings from morphological, osteological, electrophoretic, immunological and hybridization studies. Chromosome inversions and translocations have played a role in chromosome evolution of the species examined. Populations of H. chrysoscelis have probably been involved in the origin of the tetraploid species H. versicolor. Two chromosome polymorphisms were discovered in the populations of H. chrysoscelis studied.

Hyla chrysoscelis and Hyla versicolor are a diploid-tetraploid complex of morphologically indistinguishable species of treefrogs. Karyotypes, male reproductive calls, electrophoretic patterns, albumin immunology and external morphology have been determined for relatively few areas of these species ranges. Several explanations of the origin of the tetraploid from its diploid progenitor have been hypothesized. Most recently, Ralin et al. compared allele frequencies of H. chrysoscelis and H. versicolor and proposed that H. versicolor had a single origin from central populations of H. chrysoscelis during the Sangamon interglacial period. However, the distributions of these species in large areas of their collective range is unknown, and whether present distributions of H. chrysoscelis and H. versicolor are compatible with a single, central origin of the tetraploid species is poorly understood. (DBO)

The phorbol ester, 12-0-tetradecanoyl-phorbol-13-acetate (TPA) was used as a comitogen with the plant lectins phytohemagglutinin (PHA) and concanavalin A (ConA) in short-term cultures of whole blood from nonmammalian vertebrates. Stimulation with TPA in addition to standard mitogens resulted in a synergistic effect, consistently yielding more metaphases than cultures stimulated with either PHA, ConA, or TPA alone and is successful with blood samples as small as 0.1 ml. The increased mitotic index makes it possible to use different banding procedures for systematic studies. Also, because the amount of blood needed is so small, this procedure, unlike other published techniques, does not require the destruction of smaller animals to do chromosome studies.