Genética da conservação aplicada ao tráfico ilegal de aves

Birds represent the greater part of the animals associated to illegal trade/commerce in Brazil, specially due to some characteristics as song and feathers colors. Nowadays, genetic analyses comprehend one of the most effi cient approaches to generate data in order to solve and minimize the results of environmental crimes and illegal trade of wild animals. In birds, one of the genetic survey that can be used to subside conservation plans associated to illegal trade refers to molecular sexing, since it is not possible to identify the gender in some avian species based on morphological characters. The molecular sexing can be performed using DNA from different samples, as feathers and blood, and further amplifi cation of the CHD-Z e CHD-W (chromo helicaseDNA binding) gene regions. The sex-specifi c genetic profi les can support conservation programs of captive maintenance and/or reproduction and subsequent release or reintroduction of the animals on wild environment.Entre os animais silvestres envolvidos em tráfico/comércio ilegal no Brasil, as aves compreendem um dos grupos mais atingidos, especialmente devido a características como canto e colorido das penas. Atualmente, análises genéticas compreendem uma das formas mais eficazes de gerar dados para solucionar e minimizar os resultados de crimes ambientais e comércio ilegal de animais silvestres. Uma das análises genéticas que podem ser utilizadas com o intuito de subsidiar programas conservacionistas associados ao tráfico ilegal de aves refere-se à sexagem molecular, dado que neste grupo de vertebrados nem sempre é possível identificar o gênero por meio de caracteres morfológicos. A sexagem molecular pode ser feita com base em amostras de DNA obtidas de diferentes fontes, como penas e sangue, e posterior amplificação de regiões dos genes CHD-Z e CHD-W (chromo helicase-DNA binding). Os dados de perfis genéticos sexoespecíficos servem de subsídio a programas conservacionistas de manutenção e/ou reprodução em cativeiro e posterior soltura ou reintrodução dos animais em ambiente natural

Organization and Variation Analysis of 5S rDNA in Different Ploidy-level Hybrids of Red Crucian Carp × Topmouth Culter

Through distant crossing, diploid, triploid and tetraploid hybrids of red crucian carp (Carassius auratus red var., RCC♀, Cyprininae, 2n = 100) × topmouth culter (Erythroculter ilishaeformis Bleeker, TC♂, Cultrinae, 2n = 48) were successfully produced. Diploid hybrids possessed 74 chromosomes with one set from RCC and one set from TC; triploid hybrids harbored 124 chromosomes with two sets from RCC and one set from TC; tetraploid hybrids had 148 chromosomes with two sets from RCC and two sets from TC. The 5S rDNA of the three different ploidy-level hybrids and their parents were sequenced and analyzed. There were three monomeric 5S rDNA classes (designated class I: 203 bp; class II: 340 bp; and class III: 477 bp) in RCC and two monomeric 5S rDNA classes (designated class IV: 188 bp, and class V: 286 bp) in TC. In the hybrid offspring, diploid hybrids inherited three 5S rDNA classes from their female parent (RCC) and only class IV from their male parent (TC). Triploid hybrids inherited class II and class III from their female parent (RCC) and class IV from their male parent (TC). Tetraploid hybrids gained class II and class III from their female parent (RCC), and generated a new 5S rDNA sequence (designated class I–N). The specific paternal 5S rDNA sequence of class V was not found in the hybrid offspring. Sequence analysis of 5S rDNA revealed the influence of hybridization and polyploidization on the organization and variation of 5S rDNA in fish. This is the first report on the coexistence in vertebrates of viable diploid, triploid and tetraploid hybrids produced by crossing parents with different chromosome numbers, and these new hybrids are novel specimens for studying the genomic variation in the first generation of interspecific hybrids, which has significance for evolution and fish genetics

The 5S rDNA family evolves through concerted and birth-and-death evolution in fish genomes: an example from freshwater stingrays

Background: Ribosomal 5S genes are well known for the critical role they play in ribosome folding and functionality. These genes are thought to evolve in a concerted fashion, with high rates of homogenization of gene copies. However, the majority of previous analyses regarding the evolutionary process of rDNA repeats were conducted in invertebrates and plants. Studies have also been conducted on vertebrates, but these analyses were usually restricted to the 18S, 5.8S and 28S rRNA genes. The recent identification of divergent 5S rRNA gene paralogs in the genomes of elasmobranches and teleost fishes indicate that the eukaryotic 5S rRNA gene family has a more complex genomic organization than previously thought. The availability of new sequence data from lower vertebrates such as teleosts and elasmobranches enables an enhanced evolutionary characterization of 5S rDNA among vertebrates.Results: We identified two variant classes of 5S rDNA sequences in the genomes of Potamotrygonidae stingrays, similar to the genomes of other vertebrates. One class of 5S rRNA genes was shared only by elasmobranches. A broad comparative survey among 100 vertebrate species suggests that the 5S rRNA gene variants in fishes originated from rounds of genome duplication. These variants were then maintained or eliminated by birth-and-death mechanisms, under intense purifying selection. Clustered multiple copies of 5S rDNA variants could have arisen due to unequal crossing over mechanisms. Simultaneously, the distinct genome clusters were independently homogenized, resulting in the maintenance of clusters of highly similar repeats through concerted evolution.Conclusions: We believe that 5S rDNA molecular evolution in fish genomes is driven by a mixed mechanism that integrates birth-and-death and concerted evolution