Faculdade de Ciências Biológicas - FBIO/IECOS

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2253

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Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Innovative molecular approach to the identification of Colossoma macropomum and its hybrids
(2012-06) CUNHA, Maria de Fátima Gomes; SCHNEIDER, Horacio; BARROS, Maria Claudene; SAMPAIO, Dioniso de Souza; HASHIMOTO, Diogo Teruo; PORTO-FORESTI, Fábio; SAMPAIO, Maria Iracilda da Cunha
Tambaqui (Colossoma macropomum) is the fish species most commonly raised in the Brazilian fish farms. The species is highly adaptable to captive conditions, and is both fast-growing and relatively fecund. In recent years, artificial breeding has produced hybrids with Characiform species, known as "Tambacu" and "Tambatinga". Identifying hybrids is a difficult process, given their morphological similarities with the parent species. This study presents an innovative molecular approach to the identification of hybrids based primarily on Multiplex PCR of a nuclear gene (α-Tropomyosin), which was tested on 93 specimens obtained from fish farms in northern Brazil. The sequencing of a 505-bp fragment of the Control Region (CR) permitted the identification of the maternal lineage of the specimen, all of which corresponded to C. macropomum. Unexpectedly, only two CR haplotype were found in 93 samples, a very low genetic diversity for the pisciculture of Tambaqui. Multiplex PCR identified 42 hybrids, in contrast with 23 identified by the supplier on the basis of external morphology. This innovative tool has considerable potential for the development of the Brazilian aquaculture, given the possibility of the systematic identification of the genetic traits of both fry-producing stocks, and the fry and juveniles raised in farms.
Acesso aberto (Open Access)
Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)
(2009-12) BARROS, Maria Claudene; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio; BONINO, Alfredo Ricardo Langguth
A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree was enriched with the area of occurrence and with information on the karyotype of the samples. Based on this enriched tree, and with a described methodology, hypotheses were proposed on the karyotype and area of occurrence of the ancestors of each Clade. Thus it was possible to discuss hypotheses on chromosome evolution of the group, and on dispersion events from the "area of original differentiation" of akodontines in the Andes. Chromosome evolution started with high diploid numbers (2n=52) and showed a tendency to reduction (until 2n=14 in more recent clades). Independent side-branches of the tree showed 2n reduction and in one case the 2n increased. At least four dispersion events from the Andes down to South-eastern Brazil were proposed. The results should suggest the direction of new studies on comparative karyology.
Acesso aberto (Open Access)
Novel 12S mtDNA findings in sloths (Pilosa, Folivora) and anteaters (Pilosa, Vermilingua) suggest a true case of long branch attraction
(2008) BARROS, Maria Claudene; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
We sequenced 12S RNA mtDNA for the majority of the extant species of sloths and anteaters and compared our results with previous data obtained by our group using 16S RNA mtDNA in the same specimens and to GenBank sequences of the extinct giant sloth Mylodon. Our results suggest that pigmy-anteaters may be a case of the long-branch attraction phenomenon and also show the large genetic difference between the Amazonian and Atlantic forest three-toed sloths, contrasting with the small differences observed between the two non-Atlantic forest forms of sloths. These results have important implications for the taxonomy of sloths and anteaters and strongly suggest the placement of pigmy anteaters in their own family (Cyclopidae) and raising the taxonomic status of Bradypus torquatus to a genus.
Acesso aberto (Open Access)
Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters
(2003) BARROS, Maria Claudene; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths and anteaters) and used these sequences along with GenBank sequences of both extant and extinct sloths to perform phylogenetic analysis based on parsimony, maximum-likelihood and Bayesian methods. By increasing the taxa density for anteaters and sloths we were able to clarify some points of the Pilosa phylogenetic tree. Our mitochondrial 16S results show Bradypodidae as a monophyletic and robustly supported clade in all the analysis. However, the Pleistocene fossil Mylodon darwinii does not group significantly to either Bradypodidae or Megalonychidae which indicates that trichotomy best represents the relationship between the families Mylodontidae, Bradypodidae and Megalonychidae. Divergence times also allowed us to discuss the taxonomic status of Cyclopes and the three species of three-toed sloths, Bradypus tridactylus, Bradypus variegatus and Bradypus torquatus. In the Bradypodidae the split between Bradypus torquatus and the proto-Bradypus tridactylus / B. variegatus was estimated as about 7.7 million years ago (MYA), while in the Myrmecophagidae the first offshoot was Cyclopes at about 31.8 MYA followed by the split between Myrmecophaga and Tamandua at 12.9 MYA. We estimate the split between sloths and anteaters to have occurred at about 37 MYA.

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Navegando Faculdade de Ciências Biológicas - FBIO/IECOS por Autor "BARROS, Maria Claudene"