Chromosomal evolution in Gekkonidae. I. Chromosome painting between Gekko and Hemidactylus species reveals phylogenetic relationships within the group

Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6.

A Comparative Cytogenetic Analysis of 2 Bothriuridae Species and Overview of the Chromosome Data of Scorpiones

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Application of dissociation curve analysis to radiation hybrid panel marker scoring: generation of a map of river buffalo (B-bubalis) chromosome 20

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosome analysis in Pseudopaludicola (Anura, Leiuperidae), with description of sex chromosomes XX/XY in P-saltica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Different responses to doxorubicin-induced chromosome aberrations in Brazilian deer species

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sex chromosome differentiation in Belostoma (Insecta: Heteroptera: Belostomatidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chromosome banding patterns of four species of bats, with special reference to a case of X-autosome translocation

The karyotypes of 4 species of bats, Artibeus lituratus (Phyllostomatidae), Pipistrellus pipistrellus (Vespertilionidae), Pteropus alecto and P. giganteus (Pteropodidae), were studied after several banding techniques. For A. lituratus, in which an X-autosome translocation was observed, an analysis of the replication pattern in the rearranged chromosome was also made after BrdU incorporation.

Chromosome numbers and their taxonomic implications for eight Brazilian andropogons (Poaceae: Andropogoneae)

Eleven chromosome counts are reported for Brazilian populations of eight species of Andropogon. Counts for five of the species are first reports for the species. Four of these species, A. arenarius, A. glaziovii, A. lateralis, and A. lindmanii, are hexaploids (n=30) and belong to a group of about a dozen species informally referred to as the Andropogon lateralis complex. Two other species of this complex, A. bicornis and A. hypogynus, we also found to be hexaploids, in agreement with previous reports. Diploid counts (n=10) for A. macrothrix (a first report) and A. virgatus (the same as two previous reports) support the morphological affinities of these two species to other species complexes within Andropogon. © 1986 the New York Botanical Garden.

Interstitial long-arm deletion of chromosome 7 and ectrodactyly

An interstitial deletion of 7q21 was found in a boy with mental retardation, microcephaly, convergent strabismus, micrognathia, genital anomalies, and other findings, including ectrodactyly.

A case of terminal long arm deletion of chromosome 6

A four-year-old girl with deletion of chromosomal band 6q24 → qter is described. Clinical features include growth and psychomotor retardation, microcephaly, convergent strabismus, bulbous nose, long philtrum, short neck and cardiopathy.

New occurrence of a macro B-chromosome in Astyanax scabripinnis paranae (Pisces, Characiformes, Characidae)

Cytogenetic studies performed on 17 specimens (11 females and six males) of Astyanax scabripinnis paranae from the Cascatinha stream showed that this population has 2n = 50 chromosomes (8M + 22SM + 10ST + 10A), two chromosome pairs with NORs and conspicuous C-band positive blocks in the terminal position of the long arm of five chromosome pairs. Three females presented 2n = 51 chromosomes and the extra chromosome was a large metacentric similar in size and morphology to the first chromosome pair in the karyotype. This accessory chromosome was entirely heterochromatic in C-banded metaphases, which permitted its classification as a supernumerary chromosome. Some aspects related to the morphology of such macro B-chromosomes are discussed.

Paracentric inversion involving a NOR-bearing chromosome of rainbow trout (Oncorhyncus mykiss): Electron microscopy studies of the synaptonemal complex

Cytogenetic studies conduced on a sample of 19 specimens of rainbow trout (Oncorhyncus mykiss) showed that 6 presented two chromosomes with a single subterminal AgNOR on the short arms and 13 presented one chromosome with a single subterminal Ag-NOR and a second chromosome with two small subterminal Ag-NORs. Synaptonemal complex studies showed the presence of a pairing failure involving the two lateral elements (LEs) of the NOR-bearing chromosomes only in those specimens with two different NOR-bearing chromosomes, suggesting that the chromosomes with two Ag-NORs originated from a paracentric inversion involving a terminal segment of the original NOR-bearing chromosome. A comparative analysis between three normal and three heterozygous fishes suggest that in the latter group the LEs of the NOR-bearing chromosomes initiate the synaptic process in a more delayed manner, the synapsis develops more quickly, and the nucleolus stays associated with chromosomes for a longer time.

Chromosome sensitivity to bleomycin in G2 lymphocytes from Down syndrome patients

Several studies have demonstrated that lymphocytes from patients with Down syndrome (DS) exhibit an increased frequency of chromosome aberrations when they are exposed to ionizing radiation or to chemicals at the G0 or G1 phases of the cell cycle, but not at G2 when compared to normal subjects. To determine the susceptibility of DS lymphocytes at G2 phase, bleomycin, a radiomimetic agent, was used to induce DNA breaks in blood cultures from 24 Down syndrome patients. All the patients with DS showed free trisomy 21 (47,XX + 21 or 47,XY + 21). Individuals that showed an average number of chromatid breaks per cell higher than 0.8 were considered sensitive to the drug. No control child showed susceptibility to bleomycin, and among the 24 patients with DS, only one was sensitive to the drug. No significant difference was observed between the two groups, regarding chromatid break frequencies in treated G2 lymphocytes. The distribution of bleomycin-induced breaks in each group of chromosomes was similar for DS and controls. No significant difference was found in the response to bleomycin between male and female subjects. Probably, the main factor involved in chromosome sensitivity of lymphocytes from patients with DS is the phase of the cell cycle in which the cell is treated.