Effects of environmental pollution on the rDNAomics of Amazonian fish.

Pollution is a growing environmental problem throughout the world, and the impact of human activities on biodiversity and the genetic variability of natural populations is increasingly preoccupying, given that adaptive processes depend on this variability, in particular that found in the repetitive DNA. In the present study, the mitochondrial DNA (COI) and the distribution of repetitive DNA sequences (18S and 5S rDNA) in the fish genome were analysed in fish populations inhabiting both polluted and unpolluted waters in the northern Amazon basin. The results indicate highly complex ribosomal sequences in the fish genome from the polluted environment because these sequences are involved primarily in the maintenance of genome integrity, mediated by a systematic increase in the number of copies of the ribosomal DNA in response to changes in environmental conditions.

Comparative Cytotaxonomy of Two Species of Fish from the Genus Satanoperca Reveals the Presence of a B Chromosome.

The taxonomy of Satanoperca spp. is still unresolved, especially because coloring, one of the main diagnostic characters, is variable among species of this genus. Thus, the aim of this study was to elucidate the relationship between the genome and the organization of the chromosome in two Satanoperca species.

Genomic Organization Under Different Environmental Conditions: Hoplosternum Littorale as a Model.

The Amazon has abundant rivers, streams, and floodplains in both polluted and nonpolluted environments, which show great adaptability. Thus, the goal of this study was to map repetitive DNA sequences in both mitotic chromosomes and erythrocyte micronuclei of tamoatás from polluted and nonpolluted environments and to assess the possible genotoxic effects of these environments. Individuals were collected in Manaus, Amazonas (AM), and submitted to classical and molecular cytogenetic techniques, as well as to a blood micronucleus test.

Cytogenetic analyses of five amazon lizard species of the subfamilies Teiinae and Tupinambinae and review of karyotyped diversity the family Teiidae.

Lizards of the family Teiidae (infraorder Scincomorpha) were formerly known as Macroteiidae. There are 13 species of such lizards in the Amazon, in the genera Ameiva (Meyer, 1795), Cnemidophorus (Wagler, 1830), Crocodilurus (Spix, 1825), Dracaena (Daudin, 1801), Kentropyx (Spix, 1825) and Tupinambis (Daudin, 1802). Cytogenetic studies of this group are restricted to karyotype macrostructure.