oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Search Results: 1 - 10 of 2600 matches for " Iracilda Sampaio "
All listed articles are free for downloading (OA Articles)
Page 1 /2600
Display every page Item
The morphology of the foregut of larvae and postlarva of Sesarma curacaoense De Man, 1892: a species with facultative lecithotrophy during larval development
Melo, Marlon Aguiar;Abrunhosa, Fernando;Sampaio, Iracilda;
Acta Amazonica , 2006, DOI: 10.1590/S0044-59672006000300014
Abstract: previous study on the resistance of larvae of sesarma curacaoense submitted to starvation has revealed a facultative lecithotrophy during zoeal stages, but megalopa and first juvenile stages are exclusively feeding stages. in the present study, the gross morphology and fine structure of the foregut of s. curacaoense were investigated during larval, megalopa and first juvenile stages. the foregut of the zoea i show specific setae and a filter press apparently functional. the foregut undergoes changes in the zoea ii (last larval stage) with increment of setae number, mainly on the cardiopyloric valve and complexity of the filter press. after metamorphosis to megalopa stage the foregut become rather complex, with a gastric mill supporting a medial and two lateral teeth well-developed. the foregut of the first juvenile is more specialized compared to the previous stage, showing similar characteristics of the decapod adults. these results provide further evidence of facultative lecithotrophic development in the larvae of s. curacaoense.
Novel 12S mtDNA findings in sloths (Pilosa, Folivora) and anteaters (Pilosa, Vermilingua) suggest a true case of long branch attraction
Barros, Maria Claudene;Sampaio, Iracilda;Schneider, Horacio;
Genetics and Molecular Biology , 2008, DOI: 10.1590/S1415-47572008000400029
Abstract: 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.
Genetic differentiation of Macrodon ancylodon (Sciaenidae, Perciformes) populations in Atlantic coastal waters of South America as revealed by mtDNA analysis
Santos, Sim?ni;Schneider, Horacio;Sampaio, Iracilda;
Genetics and Molecular Biology , 2003, DOI: 10.1590/S1415-47572003000200008
Abstract: the king weakfish (pescada-gó in portuguese - macrodon ancylodon (sciaenidae), a demersal (bottom-feeding) species found in south america atlantic coastal waters from the gulf of paria in venezuela to baia blanca in argentina, is an economically important species because of its abundance and wide acceptance by consumers. because of its wide distribution this fish may be subject to geographic isolation and this may have resulted in distinct populations along its coastal range. considering that this species represents an important economic resource, confirmation of whether m. ancylodon is a single species or there are different genetic stocks spread over its wide distribution would be an important contribution to conservation policies and population management of the king weakfish. to investigate differences between king weakfish populations we used the cytochrome b and 16s rrna genes to characterize m. ancylodon specimens caught throughout its south american range from venezuela to argentina. our results clearly distinguished two genetically different groups which show nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species, disagreeing with the widely accepted traditional taxonomy that accepts only one species of macrodon in the western atlantic.
Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters
Barros, Maria Claudene;Sampaio, Iracilda;Schneider, Horacio;
Genetics and Molecular Biology , 2003, DOI: 10.1590/S1415-47572003000100002
Abstract: 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.
Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters
Barros Maria Claudene,Sampaio Iracilda,Schneider Horacio
Genetics and Molecular Biology , 2003,
Abstract: 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.
Genetic differentiation of Macrodon ancylodon (Sciaenidae, Perciformes) populations in Atlantic coastal waters of South America as revealed by mtDNA analysis
Santos Sim?ni,Schneider Horacio,Sampaio Iracilda
Genetics and Molecular Biology , 2003,
Abstract: The king weakfish (pescada-gó in Portuguese - Macrodon ancylodon (Sciaenidae), a demersal (bottom-feeding) species found in South America Atlantic coastal waters from the Gulf of Paria in Venezuela to Baia Blanca in Argentina, is an economically important species because of its abundance and wide acceptance by consumers. Because of its wide distribution this fish may be subject to geographic isolation and this may have resulted in distinct populations along its coastal range. Considering that this species represents an important economic resource, confirmation of whether M. ancylodon is a single species or there are different genetic stocks spread over its wide distribution would be an important contribution to conservation policies and population management of the king weakfish. To investigate differences between king weakfish populations we used the cytochrome b and 16S rRNA genes to characterize M. ancylodon specimens caught throughout its South American range from Venezuela to Argentina. Our results clearly distinguished two genetically different groups which show nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species, disagreeing with the widely accepted traditional taxonomy that accepts only one species of Macrodon in the western Atlantic.
Molecular discrimination of pouched four-eyed opossums from the Mamirauá Reserve in the Brazilian Amazon
Nunes, Cláudia;Ayres, Jose Marcio;Sampaio, Iracilda;Schneider, Horacio;
Genetics and Molecular Biology , 2006, DOI: 10.1590/S1415-47572006000200015
Abstract: previous cytochrome b (cytb) mtdna studies have suggested four species for the opossum genus philander (four-eyed opossums), three (p. mcilhennyi, p. andersoni and p. opossum) from the amazon and one (p. frenata) from the brazilian atlantic forest. during a faunal survey nine specimens of philander sp. and four of didelphis marsupialis were collected in the mamirauá sustainable reserve, amazonas state, brazil. preliminary analyses based on morphology and geographical distributions were not conclusive, suggesting that philander specimens could belong to either p. andersoni or p. opossum. in order to elucidate the relationship of this taxon to the remaining amazonian taxa, seven philander and two didelphis specimens animals were sequenced for the cytb mtdna gene and compared to other previously studied taxa. the maximum likelihood (ml), neighbor-joining (nj) and maximum parsimony (mp) consensus bootstrap trees depicted six groups: didelphis., p. frenata, p andersoni, p. mcilhennyi, p.o. opossum and philander sp. and philander canus in a common assemblage supported by significant bootstrap values, suggesting that the philander sp. from mamiraua in fact belongs to the species philander canus.
Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage
Vinson, Christina;Gomes, Grazielle;Schneider, Horacio;Sampaio, Iracilda;
Genetics and Molecular Biology , 2004, DOI: 10.1590/S1415-47572004000200008
Abstract: sciaenids are fish which are normally abundant in tropical estuaries of the western atlantic. studies on the caeté river estuary in the northern brazilian state of pará have revealed that in this area sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. in this paper we present the results of the first phylogenetic study on south american estuarine sciaenids, during which we obtained mitochondrial gene 16s sequences from 15 species belonging to eight genera occurring in the caeté estuary. intergeneric nucleotide divergences varied from 5 to 15%, lonchurus and menticirrhus being the most divergent lineages. nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (stellifer microps x stellifer naso) to 8.4% (menticirrhus americanus x menticirrhus littoralis). cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western atlantic sciaenid assemblage. our analysis further reveals a very close relationship between bairdiella and stellifer, a monophyletic clade which emerged during the more recent diversification events of the sciaenidae family. the phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the bairdiella/stellifer group.
Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)
Barros, Maria Claudene;Sampaio, Iracilda;Schneider, Horacio;Langguth, Alfredo;
Iheringia. Série Zoologia , 2009, DOI: 10.1590/S0073-47212009000400006
Abstract: 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.
Mitochondrial DNA-like sequence in the nuclear genome of Saguinus (Callitrichinae, Primates): transfer estimation
Vallinoto Marcelo,Sena Leonardo,Sampaio Iracilda,Schneider Horacio
Genetics and Molecular Biology , 2000,
Abstract: Mitochondrial DNA-like sequences have been found in the nuclei of a variety of organisms. These nuclear pseudogenes can be used to estimate relative evolutionary rates of mitochondrial genes, and can be used as outgroups in phylogenetic analyses. In this study, mitochondrial sequences with pseudogene-like characteristics, including deletions and/or insertions and stop codons, were found in tamarins (Saguinus spp., Callitrichinae, Primates). Phylogenetic analysis allowed estimation of the timing of the migration of these sequences to the nuclear genome, and also permitted inferences on the phylogeny of the genus. The choice of an inadequate outgroup (Aotus infulatus) prevented a good phylogenetic resolution of the subfamily Callitrichinae. The relatively ancient divergence of the Cebidae (Callitrichinae, Aotinae and Cebinae) may have favored confounding homoplasies.
Page 1 /2600
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.