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)

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.

Increased B chromosome frequency and absence of drive in the fish Prochilodus lineatus

The neotropical freshwater fish species Prochilodus lineatus (Pisces, Prochilodontidae) shows 2n = 54 chromosomes plus supernumerary microchromosomes ranging in number from zero to seven among different animals. The transmission rates of B chromosomes were studied by the analysis of the parental and F1 generations in 10 controlled crosses performed with specimens from a natural population. The mean transmission rate observed for B chromosomes (k(B) = 0.511) was consistent with that expected from a regular meiotic behaviour orbs in both sexes and with the theoretical value under a Mendelian mode of transmission (0.5). Possible explanations for the dramatic increase in B frequency observed in this population during the last 10 years are discussed, bearing in mind the current absence of drive.

A cytogenetic study of Diplomystes mesembrinus (Teleostei, Siluriformes, Diplomystidae) with a discussion of chromosome evolution in siluriforms

The mitotic chromosomes, nucleolus organizer regions (NORs), C-banding pattern and nuclear DNA content of Diplomystes mesembrinus were studied. The karyotype, with 2n=56 chromosomes (22m+24sm+6st+4a), has a high chromosome arm number (NF = 102), one chromosome pair with NORs, and a very small amount of heterochromatin. The NOR-bearing arm is entirely heterochromatic and exhibits a marked size polymorphism. The diploid DNA content detected in erythrocyte nuclei of D. mesembrinus was 2.57 ± 0.15 pg/nucleus. The chromosome evolution in Siluriformes is discussed on the basis of available cytogenetic data and it is proposed that 2n=56 is synapomorphic for the order.

In vivo clastogenicity assessment of the Austroplenckia populnea (Celastraceae) leaves extract using micronucleus and chromosome aberration assay

The clastogenic effect of the A. populnea leaves extract was tested in vivo on bone marrow cells of Wistar rats by evaluating the induction of chromosome aberrations and micronuclei induction on polychromatic erythrocytes. The extract was administered by gavage at doses of 300, 600 and 900mg/kg body weight. Experimental and control animals were submitted to euthanasia 24 h after the treatment. Under the conditions used, A. populnea leaves extract did not induce decrease in mitotic index and did not induce a statistically significant increase in the mean number of micronucleated polychromatic erythrocytes or chromosome aberrations in the bone marrow cells of Wistar rats. © 2007 The Japan Mendel Society.

Chromosomal diversification of diploid number, heterochromatin and rDNAs in two species of Phanaeus beetles (Scarabaeidae, Scarabaeinae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chromosome Evolution in Dendropsophini (Amphibia, Anura, Hylinae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetic analysis in three Bryconamericus species (Characiformes, Characidae): first description of the 5S rDNA-bearing chromosome pairs in the genus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The conservation of number and location of 18S sites indicates the relative stability of rDNA in species of Pentatomomorpha (Heteroptera)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

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

A method for chromosome preparations from large fish specimens using in vitro short-term treatment with colchicine

This paper describes a new technique for preparing mitotic fish chromosomes using short-term in vitro treatment with colchicine. The results show that a large number of good quality metaphases (many suitable for chromosome banding) can be obtained by this technique, which requires an average of 1 h and 30 min for all steps. The procedure considerably reduces the time normally required for chromosome preparations in fish.