Whole-genome duplication and hemoglobin differentiation traits between allopatric populations of Brazilian Odontophrynus americanus species complex (Amphibia, Anura).

Two allopatric populations of Brazilian diploid and tetraploid Odontophrynus americanus species complex, both from São Paulo state, had their blood hemoglobin biochemically analyzed. In addition, these specimens were cytogenetically characterized. Biochemical characterization of hemoglobin expression showed a distinct banding pattern between the allopatric specimens.

Polyploidy and epigenetic events in the evolution of Anura.

This article reviews the polyploidy events that have long been demonstrated to play a role in the evolution of Anura, while also discussing the importance of epigenetic control of gene expression and diversity. Findings on Brazilian autopolyploid anurans, mainly of the genus Odontophrynus, obtained in previous studies on their cytogenetics, chromatin ultrastructure, and molecular gene regulation are discussed here. Our data on genome duplication and on epigenetic events were analyzed here regarding phylogenetic trees, including the classic 2R model for vertebrate evolution and the growing evidence of similar epigenetic mechanisms in animal and allopolyploid plants.

The kinin B(2) receptor gene structure, product processing and expression in adult and fetal rats: evidence for gene evolution.

We examined the structure of the rat kinin B2 receptor gene (KB2r) and encoding messenger RNA (mRNA) processing. Differently from the closely related mouse and rabbit genes that have three exons and two introns, the rat gene purportedly consists of four exons and three introns. There are two purported gene products; one of them contains an upstream approximately 180-bp open reading frame region ("exon-X") potentially expressed as a result of alternative processing.

Pore-linked filaments in anura spermatocyte nuclei.

Pore-linked filaments were visualized in spreads of anuran spermatocyte nuclei using transmission electron microscope. We used Odontophrynus diplo and tetraploid species having the tetraploid frogs reduced metabolic activities. The filaments with 20-40 nm width are connected to a ring component of the nuclear pore complex with 90-120 nm and extend up to 1 microm (or more) into the nucleus.

Evolution by polyploidy and gene regulation in Anura.

The evolution of the metazoa has been characterized by gene redundancy, generated by polyploidy, tandem duplication and retrotransposition. Polyploidy can be detected by looking for duplicated chromosomes or segments of orthologous chromosomes in post-polyploid animals. It has been proposed that the evolutionary role of polyploidy is to provide extra-copies of genes, whose subsequent alteration leads to new functions, increased biological complexity, and, ultimately, speciation.