44 research outputs found
Does the Polymorphism in the Length of the Polyalanine Tract of FOXE1
Background. Recent data have suggested that polymorphisms in the length of the polyalanine tract (polyA) of FOXE1 gene may act as a susceptibility factor for thyroid dysgenesis. The main purpose of this study was to investigate the influence of polyA of FOXE1 gene on the risk of thyroid dysgenesis. Method. A case-control study was conducted in a sample of 90 Brazilian patients with thyroid dysgenesis and 131 controls without family history of thyroid disease. Genomic DNA was isolated from peripheral blood samples and the genotype of each individual was determined by automated sequencing. Results. More than 90% of genotypes found in the group of patients with thyroid dysgenesis and in controls subjects were represented by sizes 14 and 16 polymorphisms in the following combinations: 14/14, 14/16, and 16/16. Genotypes 14/16 and 16/16 were more frequent in the control group, while genotype 14/14 was more frequent in the group of patients with thyroid dysgenesis. There was no difference between agenesis group and control group. Genotype 14/14 when compared to genotypes 14/16 and 16/16A showed an association with thyroid dysgenesis. Conclusion. PolyA of FOXE1 gene alters the risk of thyroid dysgenesis, which may explain in part the etiology of this disease
Caracterização citogenética de um Craniofaringioma por bandeamento G/ Cytogenetic characterization of a Craniopharyngioma by g banding
Os Cânceres do Sistema Nervoso Central (SNC) representam cerca de 2% de todas as neoplasias. Por afetar o sistema nervoso mostram uma grande variação de sintomas, porque esse órgão coordena todas as funções do corpo. Craniofaringiomas são tumores da região selar presumivelmente derivado de bolsa do epitélio Rathke, com um comportamento benigno. Os casos de craniofaringiomas correspondem a 1,2 a 4,6% dos tumores do SNC. Duas variantes são conhecidas: craniofaringioma adamantinomatoso e papilar. Pouco se sabe sobre alterações cromossômicas deste tipo de tumor, e os estudos por CGH falharam em demostrar alterações cromossômicas especificas até o momento e sugeriram que a presença de múltiplas alterações cromossômicas são eventos raros em craniofaringioma. Nosso trabalho teve como objetivo caracterizar as anormalidades cromossômicas de um paciente com craniofaringioma. A amostra foi obtida no Hospital Ophir Loyola, Belém-PA, e foi cultivada após desagregação enzimática (colagenase tipo IV) para obtenção de cromossomos. As células foram cultivadas com DMEM suplementado com 10% de Soro Bovino Fetal. A colheita cromossômica foi feita com 0,1 ml de colcemid e KCl 0,075 M foi usado para a hipotonização. As lâminas com os cromossomos foram incubadas a 37 ° C por 24 horas antes do tratamento com 2 x SSC a 45 ° C por min 2'30''. A coloração foi realizada em tampão fosfato (pH 6,8) e Wright (3:1). As aquisições de imagens foram feitas em um microscópio Leyca DM 500 com uma câmera ICC Leyca HD 50. Após análise observamos cariótipos muito complexos, com alterações numéricas e estruturais em quase todos os pares de cromossomos. Os números de cromossomos variaram de 44 a 52, exibindo cariótipos próximos a diploidia. O número modal de cromossomos foi de 46. Sendo assim foi construído o seguinte cariótipo composto: 44~52, XY, -X, del (1)(p32-> pter), +2, -4, del (6)(q24 -> qter), -7, -8, -9, -9, -10, +10, +11, -12, +12, +13, +14, -15, +15, -16, -17, +18, -20, -21, +21, +22, +r, +mar(x3), para demostrar as alterações clonais. Os craniofaringiomas foram pouco analisados citogeneticamente até agora, e apenas os cromossomos, o 2 e o 12, foram consistentemente envolvidos. Nosso trabalho contribui para compreensão da biologia dos craniofaringiomas, pois, poucos casos foram citogeneticamente analisados até o momento
The molecular cytogenetic characterization of Conopophaga lineata indicates a common chromosome rearrangement in the Parvorder Furnariida (Aves, Passeriformes).
Cytogenetic analyses of the Suboscines species are still scarce, and so far, there is no karyotype description of any species belonging to the family Conopophagidae. Thus, the aim of this study is to describe and analyze the karyotype of Conopophaga lineata by chromosome painting using Gallus gallus (GGA) probes and to identify the location of the 18/28S rDNA cluster. Metaphases were obtained from fibroblast culture from two individuals of C. lineata. We observed a diploid number of 2n=78. GGA probes showed that most ancestral syntenies are conserved, except for the fission of GGA1 and GGA2, into two distinct pairs each. We identified the location of 18S rDNA genes in a pair of microchromosomes. The fission of the syntenic group corresponding to GGA2 was observed in other Furnariida, and hence may correspond to a chromosomal synapomorphy for the species of Parvorder Furnariida
Chromosomal Evolution in the Phylogenetic Context: A Remarkable Karyotype Reorganization in Neotropical Parrot Myiopsitta monachus (Psittacidae).
Myiopsitta monachus is a small Neotropical parrot (Psittaciformes: Arini Tribe) from subtropical and temperate regions of South America. It has a diploid chromosome number 2n = 48, different from other members of the Arini Tribe that have usually 70 chromosomes. The species has the lowest 2n within the Arini Tribe. In this study, we combined comparative chromosome painting with probes generated from chromosomes of Gallus gallus and Leucopternis albicollis, and FISH with bacterial artificial chromosomes (BACs) selected from the genome library of G. gallus with the aim to shed light on the dynamics of genome reorganization in M. monachus in the phylogenetic context. The homology maps showed a great number of fissions in macrochromosomes, and many fusions between microchromosomes and fragments of macrochromosomes. Our phylogenetic analysis by Maximum Parsimony agree with molecular data, placing M. monachus in a basal position within the Arini Tribe, together with Amazona aestiva (short tailed species). In M. monachus many chromosome rearrangements were found to represent autopomorphic characters, indicating that after this species split as an independent branch, an intensive karyotype reorganization took place. In addition, our results show that M. monachus probes generated by flow cytometry provide novel cytogenetic tools for the detection of avian chromosome rearrangements, since this species presents breakpoints that have not been described in other species
Cytogenetic study in the Brazilian semiarid lizard Tropidurus hispidus (Squamata, Tropiduridae)
Different classes of repetitive DNA sequences are found in eukaryotes, often composing substantial portions of the genome, associated with their important role in the structural and functional genome organization. In this work, we mapped repetitive DNA sequences (18S rDNA, microsatellites and telomeric motifs) in the karyotype of Tropidurus hispidus, a species of lizard from the Brazilian semiarid region. We found a diploid number of 2n = 36 (6 pairs of biarmed macrochromosomes and 12 pairs of microchromosomes). The 18S rDNA clusters were localized at the subterminal region of the long arm of pair 2. The telomeric probes produced signals at terminal, interstitial and centromeric positions of some chromosome pairs, which might indicate the occurrence of chromosomal rearrangements via chromosome fusions. Microsatellite sequences were found in at least two distinct patterns - clustered in the telomeric/pericentromeric regions or observed as scattered signals in the chromosomes. This study represents an initial step to explore the evolutionary dynamics of repetitive sequences in the Tropidurus genus and considering the scarcity of data concerning the chromosomal mapping of repetitive sequences in Tropiduridae species, it reinforces the importance of integrating other methodologies, including the isolation and physical mapping of different repetitive DNA sequences, contributing to understanding the patterns of karyotypic evolution in lizards.Asociación Herpetológica Argentin
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Karyotype Evolution in Birds: From Conventional Staining to Chromosome Painting.
In the last few decades, there have been great efforts to reconstruct the phylogeny of Neoaves based mainly on DNA sequencing. Despite the importance of karyotype data in phylogenetic studies, especially with the advent of fluorescence in situ hybridization (FISH) techniques using different types of probes, the use of chromosomal data to clarify phylogenetic proposals is still minimal. Additionally, comparative chromosome painting in birds is restricted to a few orders, while in mammals, for example, virtually all orders have already been analyzed using this method. Most reports are based on comparisons using Gallus gallus probes, and only a small number of species have been analyzed with more informative sets of probes, such as those from Leucopternis albicollis and Gyps fulvus, which show ancestral macrochromosomes rearranged in alternative patterns. Despite this, it is appropriate to review the available cytogenetic information and possible phylogenetic conclusions. In this report, the authors gather both classical and molecular cytogenetic data and describe some interesting and unique characteristics of karyotype evolution in birds
Dispersión geográfica de la familia Phyllostomidae (Chiroptera) basada en las secuencias del citocromo b
Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil / Universidade Federal do Pará. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Centro de Inovações Tecnológicas. Ananindeua, PA, Brasil / Universidade Estadual do Pará. Centro de Ciências Biológicas e da Saúde. Laboratório de Biologia Molecular. Belém, PA, Brasil.The Chiroptera order is one of the most successful species of mammals with a wide geographical distribution. This order
has been traditionally divided into two suborders, Microchiroptera and Megachiroptera, and the family Phyllostomidae
is included in the suborder Microchiroptera. However, studies with molecular analysis show a different classification in
two different suborders: Yangochiroptera and Yinpterochiroptera. Studies with various species describe a wide dispersal
of these animals from Central America to South America and specimens of different places, creating new karyotypes
and different nucleotide sequences, especially in the widely known Cytochrome b gene. In this study, we analyzed a
phylogeographic dispersion of the Pyllostomidae family using the mitochondrial Cytochrome b gene, a possible dispersion
pattern for family and new evolutionary proposals. All the sequences were obtained from the online database (GenBank)
and the analysis and formation of phylogenetic trees were performed by maximum parsimony and maximum likelihood
methods. Some dispersion patterns were observed for species of genus Carollia and Glossophaga in individual analysis
and other species pattern of dispersion from South to West. But in general analysis, a pattern of dispersal to the North
of the American Continent was evidenced for the family, following South America to Central America, despite many
landforms that could cause speciation of some genera such as isolation by the Andes mountains. Further analysis, with a
greater number of specimens from different locations, must be done to confirm this theoryA ordem Chiroptera é uma das espécies de mamíferos mais bem sucedidas com uma grande distribuição geográfica. Essa
ordem foi tradicionalmente dividida em duas subordens, Microchiroptera e Megachiroptera, e a família Phyllostomidae
está incluída na primeira. No entanto, estudos com análise molecular mostram uma classificação diferente em duas
subordens distintas: Yangochiroptera e Yinpterochiroptera. Os estudos com várias espécies descrevem uma grande
dispersão desses animais da América Central para a América do Sul e espécimes de vários lugares, a criação de novos
cariótipos e sequências de nucleotídeos diferentes, especialmente no gene citocromo b amplamente conhecido. Neste
estudo, analisou-se uma dispersão filogeográfica da família Pyllostomidae usando o gene mitocondrial citocromo b, um
possível padrão de dispersão para essa família e novas propostas evolutivas. Todas as sequências foram obtidas a partir
da base de dados on-line (GenBank), a análise e a formação de árvores filogenéticas foram realizadas pelos métodos
de máxima parcimônia e de máxima verossimilhança. Foram observados alguns padrões de dispersão de espécies do
gênero Carollia e Glossophaga na análise individual e outro padrão de dispersão de espécies do sul ao oeste. Porém,
na análise geral, um padrão de dispersão para o norte do Continente Americano foi evidenciado para a família, depois
da América do Sul à América Central, apesar de muitos acidentes geográficos causarem especiação de alguns gêneros,
tais como o isolamento das montanhas dos Andes. Uma análise mais aprofundada, com um maior número de amostras
de diferentes locais, deve ser feita para confirmar esta teoria
The karyotype of Alouatta fusca clamitans from Rio de Janeiro, Brazil: Evidence for a y-autosome translocation
The chromosome complements of four males of Alouatta fusca clamitans, caught in Rio de Janeiro State, Brazil, were analyzed by G-, C-, and NOR-banding techniques. The diploid number found was 49 in all the specimens. The presence of a heteromorphic pair of submetacentric chromosomes in the analyzed specimens, not present in males and females with 2n = 50 previously reported, and its G-banding pattern, led us to assume that this pair is involved in a Y-autosome translocation. Thus, the sex determination system appears modified to X1X1X2X2 /X1X2Y. Heterochromatic segments were found in the pericentromeric region of all the chromosomes, in the telomeric region of the short arm in pair 2, in the complete length of the short arm of pairs 5 and 6 and in the intercalary region of the long arm in pair 17. The nucleolar organizer regions were situated in the intercalary region of the long arm in two small acrocentric pairs.Os cariótipos referentes a quatro machos de Alouatta fusca clamitans oriundos do Rio de Janeiro foram analisados através de técnicas de bandamento G, C e NOR. O número diplóide em todos os espécimes foi igual a 49, com a presença de três cromossomos não pareados. A comparação dos padrões de bandamento G com espécimes previamente descritos com 2n = 50 revelou a ocorrência de uma translocação do tipo Y-autossomo, modificando o sistema cromossômico de determinação sexual para o tipo múltiplo, X1X2Y/X1X1 X2X2. Os blocos de heterocromatina constitutiva se distribuíram na região pericentromérica de todos os cromossomos; segmentos intercalares e teloméricos foram visualizados em um par acrocêntrico e em outro submetacêntrico, respectivamente. As regiões organizadoras de nucléolo se localizaram no braço longo de dois pares de pequenos acrocêntricos
Karyotype Organization of the Endangered Species Yellow Cardinal (Gubernatrix cristata)
Karyotypic analyses have several applications in studies of chromosome organization, evolution, and cytotaxonomy. They are also essential to genome assembly projects. Here, we present for the first time the karyotype description of the endangered species yellow cardinal, Gubernatrix cristata (Passeriformes, Thraupidae), using conventional staining with Giemsa and 18S rDNA probes. This species has 78 chromosomes, with 12 pairs of macrochromosomes and 27 microchromosome pairs. The 18S rDNA clusters were found in four microchromosomes. Our results revealed that G. cristata has a typical avian karyotype (approximately 80 chromosomes). However, G. cristata has an apomorphic state in relation to the 18S rDNA distribution since the ancestral condition corresponds to only two microchromosomes with these sequences. Probably, duplications and translocations were responsible for increasing the number of 18S rDNA clusters in G. cristata. The results were compared and discussed with respect to other Thraupidae and Passeriformes members. Considering the globally threatened status of G. cristata, we believe that its karyotype description could be a starting point for future cytogenetics and sequencing projects