RESUMO
A physical chromosome mapping of the H1 histone and 5S and 18S ribosomal RNA (rRNA) genes was performed in interspecific hybrids of Pseudoplatystoma corruscans and P. reticulatum. The results showed that 5S rRNA clusters were located in the terminal region of 2 chromosomes. H1 histone and 18S ribosomal genes were co-localized in the terminal portion of 2 chromosomes (distinct from the chromosomes bearing 5S clusters). These results represent the first report of association between H1 histone and 18S genes in fish genomes. The chromosome clustering of ribosomal and histone genes was already reported for different organisms and suggests a possible selective pressure for the maintenance of this association.
Assuntos
Peixes-Gato/genética , Proteínas de Peixes/genética , Histonas/genética , RNA Ribossômico/genética , Animais , Peixes-Gato/classificação , Mapeamento Cromossômico , Cromossomos/genética , Genes de RNAr/genética , Hibridização Genética , Hibridização in Situ Fluorescente , Família Multigênica/genética , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 18S/genética , RNA Ribossômico 5S/genéticaRESUMO
Two to 14 alleles were found to be segregating per locus (mean 5·2), with observed and expected heterozygosities ranging from 0·08 to 0·78 and 0·08 to 0·94, respectively. Cross-amplification of six of these microsatellite loci indicated that they are also polymorphic in three species of Carcharhiniformes and two species of Lamniformes. The newly developed primers reported here constitute a useful tool for genetic population analyses on Prionace glauca and, potentially, other related species.
Assuntos
Repetições de Microssatélites/genética , Tubarões/genética , Alelos , Animais , Dados de Sequência Molecular , Polimorfismo Genético , Especificidade da EspécieRESUMO
We report here on the physical mapping of the H1 histone genes (hisDNA) and the 5S ribosomal DNA (rDNA) in 3 Neotropical fish species of the genus Astyanax(A. altiparanae, A. bockmanni and A. fasciatus) and the comparative analysis of the chromosomes bearing these genes. Nucleotide analyses by sequencing of both genes were also performed. The distribution of the H1 histone genes was more conserved than that of the rRNA genes, since these were always located in the pericentromeric regions of 2 chromosome pairs. 5S rDNA was found on one of the pairs that presented an H1 histone cluster; this seems to be a conserved chromosomal feature of the genus Astyanax. In addition, individuals of A. bockmanni and A. fasciatus showed clusters of 5S rDNA on 1 pair of acrocentric chromosomes, not found in A. altiparanae. The results obtained by chromosome mapping as well as by sequencing of both genes showed that A.bockmanni is more closely related to A. fasciatus than to A. altiparanae. The results allow the characterization of cytogenetic markers for improved elucidation of the processes involved in karyotype differentiation of fish genomes.
Assuntos
Peixes/genética , Histonas/genética , Família Multigênica , RNA Ribossômico 5S/genética , Animais , Mapeamento CromossômicoRESUMO
Rhinobatos percellens, Rhinobatos horkelli and Zapteryx brevirostris, known as guitarfish, are commonly found inshore and caught by trawl nets. Recently, these species have been suffering sharp population declines. One of the main impediments to the development of conservation plans is the lack of information related to each species catch. Gathering this information is made more difficult by the fishermen's practice of removing parts of the animals before landing, as well as the morphological similarities among the three species. To address these issues, this work presents multiplex-PCR protocols that were developed to distinguish among these species using their genetic characteristics.
RESUMO
Interspecific hybrids of fish can offer important advances in the zootechnical exploration of this animal group. However, hybrids can pose serious biological risks to the environment and natural populations, making genetic characterization and monitoring of hybrids produced in fish culture important concerns. In the present study, individuals of the hybrid 'Piaupara' were characterized by fluorescence in situ hybridization (FISH) using sex-specific probes to differentiate the respective parental contributions from female Leporinus macrocephalus (Piauçu) and male Leporinus elongatus (Piapara). The application of this technique demonstrated a difference in hybridization patterns between males and females of L. elongatus and L. macrocephalus, mainly due to the fact that the NOR-bearing chromosomes of L. elongatus contain some homology with the probe. This allowed us to detect a clear sex-specific distinction of the hybrid 'Piaupara', demonstrating that this technique is well-suited for the characterization of these hybrids. Moreover, this technique offers an important methodological advance for the study of diverse sex chromosome systems of Leporinus, supplying valuable information about the origin and establishment of a recently described sexual system in this genus.
Assuntos
Sondas de DNA/metabolismo , Peixes/genética , Hibridização Genética , Sequências Repetitivas de Ácido Nucleico/genética , Cromossomos Sexuais/genética , Clima Tropical , Animais , Feminino , Masculino , Metáfase , Região Organizadora do NucléoloRESUMO
Rhizoprionodon lalandii and R. porosus are widely distributed along the Atlantic coast of the Americas, living close to coastal areas and therefore frequently captured by seaboard fisheries. However, morphological identification of species in this genus is very difficult, especially when sharks have their heads and fins removed, making information about fishing, trading, and the evaluation of fishery effects on species conservation very difficult. This study's main objective is to develop molecular tools to identify these species using multiplex polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism techniques. Both techniques result in good low-cost markers and may be very useful in future studies about the exploitation of these species.
RESUMO
Os autores relatam um caso de bezoar na infancia em um lactente com dois anos incompletos. Dado a raridade desta patologia na faixa etaria assinalada, bem como so fatores psiquicos correlacionados, e apresentado o caso, estudo radiologico realizado e terapeutica cirurgica, chamando atencao para a assistencia psiquiatrica no tratamento e prevencao de recidiva