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Non-homologous sex chromosomes in two species of the genus Eigenmannia (Teleostei : Gymnotiformes)

HENNING, F.; TRIFONOV, V.; FERGUSON-SMITH, M. A.; ALMEIDA-TOLEDO, L. F. de
Fonte: KARGER Publicador: KARGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.02%
The Neotropical genus Eigenmannia is a fish group with unknown species diversity where representatives possess a broad range of chromosomal sex determining systems namely XY/XX, X1X2Y/X1X1X2X2, ZZ/ZW as well as homomorphic sex chromosomes. To test the homology of two heteromorphic XY sex chromosome systems present in two sympatric populations, reciprocal cross-species FISH experiments were performed using probes derived by microdissection of X and Y chromosomes present in analyzed specimens of Eigenmannia virescens and Eigenmannia sp.2, respectively. While X and Y paint probes hybridized to species-specific sex chromosomes, in reciprocal cross-FISH both probes hybridized exclusively to autosomes. The result suggests multiple independent origins of the XY systems in the analyzed populations. Copyright (C) 2008 S. Karger AG, Basel.

Inferring paternal history of rural african-derived brazilian populations from y chromosomes

Kimura, L; Nunes, K; Souza, Lúcia Inês Macedo de; Auricchio, Maria Teresa Balester de Mello; Netto, Regina Celia Mingroni
Fonte: Sociedade Brasileira de Genática - SBG; Águas de Lindóia Publicador: Sociedade Brasileira de Genática - SBG; Águas de Lindóia
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
55.91%
About four million Africans were brought to Brazil as slaves during four centuries. Many communities, named quilombos, were founded by runaway or abandoned African slaves. ere are many quilombo remnants in the ‘Vale do Ribeira’ region in the southern part of São Paulo State, Brazil. In order to shed light on their origins, patterns of genetic diversity and to estimate genetic admixture, we used ve biallelic Y chromosome markers (YAP, M3, M242, M168 and M2) and a set of 17 microssatelites (AmpFlSTR Y ler, Applied Biosystems) to de ne haplotypes and haplogroups. e aim of the study was to investigate how Amerindians, Europeans and Africans contributed to the Y chromosome pool in ten African-derived populations (about 300 individuals) from ‘Vale do Ribeira’ region. Allelic and haplotype frequencies were estimated by direct counting using the Arlequin ver 3.5 software (Exco er and Lischer, 2010; Mol Ecol Resour. May; 10(3): 564-7). Haplotype diversity and degrees of interpopulational genetic variation (FST) were inferred using the same software. Y-chromosomal haplogroups predictions based on the set of microsatellites were generated using Haplogroup Predictor (http://www.hprg.com/hapest5/). Admixture analysis based on the biallelic markers indicated that 32.2% of Y chromosomes lineages were African...

"Variabilidade molecular do cromossomo Y em remanescentes de quilombos do Vale do Ribeira" ; Molecular variabilite in Y cromosome in quilombo remnants in Vale do Ribeira

Souza, Lúcia Inês Macedo de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/08/2003 PT
Relevância na Pesquisa
46.1%
Resumo O Vale do Ribeira é uma área que ocupa cerca de 10% da região sul do estado de São Paulo e abriga pelo menos 25 comunidades remanescentes de quilombos. Dessas, 13 já foram oficialmente reconhecidas ou estão em fase de reconhecimento. Com o objetivo de contribuir para o conhecimento da estrutura populacional e da história da formação desses remanescentes de quilombos, estudamos os indivíduos do sexo masculino de seis comunidades: Abobral Margem Esquerda (48), Galvão (22), São Pedro (22), Pedro Cubas (60), Pilões (15) e Maria Rosa (9), além de uma amostra de 81 homens da cidade de São Paulo, em relação a quatro locos polimórficos do cromossomo Y: dois microssatélites (DYS19 e DYS390), um SNP (DYS199) e uma inserção de Alu (DYS287). Os genótipos foram identificados por meio da amplificação do DNA pela reação em cadeia da polimerase (PCR), seguida de eletroforese em gel de poliacrilamida. Um quinto marcador foi estudado, um SNP (M168), apenas em alguns indivíduos selecionados. Nesse caso os genótipos foram identificados por seqüenciamento direto do DNA. As freqüências alélicas no DYS19 e DYS390 indicaram que nas populações por nós estudadas há uma importante contribuição patrilinear portuguesa. O SNP DYS199...

Evolução cromossômica: estudo da variabilidade cariotípica em Platyrrhini e das homeologias e sintenias com cromossomos humanos; Chromosome evolution: Karyotype variability in Platyrrhini and studies of sinteny and homologies between human chromosomes

Iughetti, Cristiani Gifalli
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/09/2008 PT
Relevância na Pesquisa
46.26%
Estudamos os cariótipos de espécimes de macacos brasileiros (Platyrrhini, Primates) com técnicas citogenéticas tradicionais e de FISH com as sondas totais dos cromossomos 14, 15 e X humanos e do cromossomo Y de Brachyteles arachnoides obtida por microdissecção cromossômica. Vinte e quatro espécimes de Alouatta guariba clamitans, doze machos e doze fêmeas foram estudados. Para os machos, encontramos um número diplóide de 2n = 49, devido à ausência aparente do cromossomo Y provavelmente decorrente de uma translocação Y-autossomo, e 2n = 46 cromossomos, com variação nas fórmulas cromossômicas com 17, 19, 20, 21 ou 24 cromossomos metacêntricos ou submetacêntricos e 22, 28, 29, 30 ou 32 acrocêntricos. Para as fêmeas, uma variabilidade maior no número diplóide foi observada com 46, 48 e 50 cromossomos e as fórmulas cromossômicas encontradas mostraram 18, 19, 20, 21, 27 ou 28 cromossomos metacêntricos ou submetacêntricos e 18, 19, 27, 30, 31 e 32 acrocêntricos. Os cromossomos X eram submetacêntricos. Pares heteromórficos foram observados. Uma fêmea com 48 cromossomos foi descrita pela primeira vez, este número diplóide só havia sido descrito em um único exemplar macho. A confirmação da subespécie dos indivíduos analisados se deu pela presença do par cromossômico característico de Alouatta guariba clamitans...

Modelos evolucionários de envelhecimento: regimes reprodutivos e a degeneração do cromossomo Y.; Evolutionary aging models: reproductive regimes and the Y chromosome degeneration.

Lôbo, Matheus Pereira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/06/2003 PT
Relevância na Pesquisa
46.11%
As teorias de envelhecimento biológico podem ser divididas em duas categorias: as teorias bioquímicas e as teorias evolucionárias. As teorias bioquímicas explicam o envelhecimento como oriundo das imperfeições dos mecanismos bioquímicos responsáveis pela manutenção da vida. As teorias evolucionárias explicam o envelhecimento sem recorrerem a mecanismos bioquímicos, mas sim a fatores adaptativos. Neste trabalho estudamos modelos teóricos de envelhecimento a luz das teorias evolucionárias. Um dos modelos evolucionários de envelhecimento mais bem-sucedido é o modelo Penna. Estudamos alguns de seus principais resultados, entre eles a senescência catastrófica e a lei de Gompertz. Discutimos também a versão sexuada do modelo, dando especial ênfase às conseqüências da fidelidade sexual e da seletividade sexual. Em 1995, simultaneamente ao surgimento do modelo Penna, foi proposto o modelo Heumann-Hotzel. Inicialmente este modelo não foi bem-sucedido devido a algumas características pouco realistas. Mas seu insucesso foi rapidamente suplantado por algumas modificações simples e essenciais. Neste trabalho investigamos, através de simulações numéricas, regimes alternativos de reprodução no modelo Heumann-Hotzel modificado. Os regimes estudados foram: reprodução sexuada com e sem recombinação genética...

Comparative RH Maps of the River Buffalo and Bovine Y Chromosomes

Stafuzza, N. B.; Abbassi, H.; Grant, J. R.; Rodrigues-Filho, E. A.; Ianella, P.; Kadri, S. M.; Amarante, M. V.; Stohard, P.; Womack, J. E.; de Leon, F. A. Ponce; Amaral, M. E. J.
Fonte: Karger Publicador: Karger
Tipo: Artigo de Revista Científica Formato: 132-138
ENG
Relevância na Pesquisa
55.99%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 02/10150-5; Processo FAPESP: 04/08768-6; Radiation hybrid maps were constructed for river buffalo and cattle Y chromosomes. A total of 41 cattle-derived Y-chromosome molecular markers were selected and tested with 2 previously described 5,000-rad whole-genome radiation hybrid (RH) panels (river buffalo - BBURH(5000) and cattle - BTARH(5000)) for generation of maps. Among the initial 41 selected markers, a subset of 26 markers generated PCR products suitable for scoring with the BBURH(5000) panel. of these, 19 markers (73%) were distributed in 1 linkage group spanning 341.3 cR. Retention frequencies (RF) for individual markers ranged from 17.8% for SMCY to 56.7% for BTY1, with an average RF of 37.6%. From the selected markers, 37 generated reliable scores using the BTARH(5000) panel. The newly constructed BTAY RH map contains 28 markers distributed within 1 linkage group. Twenty- four of these markers had been previously mapped on BTAY using a 7,000- rad cattlehamster WG- RH panel and 4 markers were mapped for the first time (ZFY, SeqRep, RepSeqS4 and BTY1). The length of the BTAY RH map was estimated to be 602.4 cR. Retention fre- quencies for individual mapped markers ranged from 10% (INRA126) to 63.3% (SeqRep)...

Recent common ancestry of human Y chromosomes: Evidence from DNA sequence data

Thomson, Russell; Pritchard, Jonathan K.; Shen, Peidong; Oefner, Peter J.; Feldman, Marcus W.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 20/06/2000 EN
Relevância na Pesquisa
46.1%
We consider a data set of DNA sequence variation at three Y chromosome genes (SMCY, DBY, and DFFRY) in a worldwide sample of human Y chromosomes. Between 53 and 70 chromosomes were fully screened for sequence variation at each locus by using the method of denaturing high-performance liquid chromatography. The sum of the lengths of the three genes is 64,120 bp. We have used these data to study the ancestral genealogy of human Y chromosomes. In particular, we focused on estimating the expected time to the most recent common ancestor and the expected ages of certain mutations with interesting geographic distributions. Although the geographic structure of the inferred haplotype tree is reminiscent of that obtained for other loci (the root is in Africa, and most of the oldest non-African lineages are Asian), the expected time to the most recent common ancestor is remarkably short, on the order of 50,000 years. Thus, although previous studies have noted that Y chromosome variation shows extreme geographic structure, we estimate that the spread of Y chromosomes out of Africa is much more recent than previously was thought. We also show that our data indicate substantial population growth in the effective number of human Y chromosomes.

A molecular and FISH analysis of structurally abnormal Y chromosomes in patients with Turner syndrome

Robinson, D; Dalton, P; Jacobs, P; Mosse, K; Power, M; Skuse, D; Crolla, J
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /04/1999 EN
Relevância na Pesquisa
46.1%
Fourteen patients with Turner syndrome and a structurally abnormal Y chromosome were analysed by PCR amplification and fluorescence in situ hybridisation for the presence of sequences specific to defined regions of the Y chromosome. Thirteen patients had a mosaic karyotype including a 45,X cell line and one case was non-mosaic in cultured lymphocytes. Ten patients had a pseudodicentric Yp chromosome, two an isodicentric Yq, one a pseudodicentric Yq, and one a derived Y chromosome. Two of the patients with a psu dic(Yp) chromosome had complex karyotypes with more than two cell lines, one of which exhibited five morphologically distinct mar(Y) chromosomes, presumably derived from a progenitor psu dic(Yp). Nine of the ten psu dic(Yp) chromosomes were positive for all Yp and Yq probes used except DYZ1 which maps to Yq12, suggesting a common breakpoint near the Yq euchromatin/heterochromatin boundary. In the three patients with a dicentric Yq chromosome two different breakpoints were observed; in two it was between PABY and the subtelomeric repeat sequence and in one it was between DYZ5 and AMGY in proximal Yp. Our results suggest that the great majority of structurally abnormal Y chromosomes found in Turner syndrome mosaics contain two copies of virtually all of the functional Y chromosome euchromatin.


Keywords: Turner syndrome; Y chromosomes; marker chromosomes; fluorescence in situ hybridisation

Distribution of Y chromosomes among Native North Americans: A study of Athapaskan population history

Malhi, Ripan Singh; Gonzalez-Oliver, Angelica; Schroeder, Kari Britt; Kemp, Brian M; Greenberg, Jonathan A.; Dobrowski, Solomon Z.; Smith, David Glenn; Resendez, Andres; Karafet, Tatiana; Hammer, Michael; Zegura, Stephen; Brovko, Tatiana
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/2008 EN
Relevância na Pesquisa
46.12%
In this study 231 Y chromosomes from 12 populations were typed for four diagnostic SNPs to determine haplogroup membership and 43 Y chromosomes from three of these populations were typed for eight Simple Tandem Repeats (STRs) to determine haplotypes. These data were combined with previously published data, amounting to 724 Y chromosomes from 26 populations in North America, and analyzed to investigate the geographic distribution of Y chromosomes among Native North Americans and to test the Southern Athapaskan migration hypothesis. The results suggest that European admixture has significantly altered the distribution of Y chromosomes in North America and because of this caution should be taken when inferring prehistoric population events in North America using Y chromosome data alone. However, consistent with studies of other genetic systems, we are still able to identify close relationships among Y chromosomes in Athapaskan from the Subarctic and the Southwest, suggesting that a small number of proto-Apachean migrants from the Subarctic founded the Southwest Athapaskan populations.

Origin and Evolution of Y chromosomes: Drosophila tales

Carvalho, A. Bernardo; Koerich, Leonardo B.; Clark, Andrew G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.09%
Classically Y chromosomes are thought to originate from X chromosomes through a process of degeneration and gene loss. Now, the availability of 12 Drosophila genomes provides the opportunity to study the origin and evolution of Y chromosomes in an informative phylogenetic context. Surprisingly, the majority of Drosophila Y-linked genes are recent acquisitions from autosomes, and Y chromosome gene gains are more frequent than gene losses. Moreover, the D. pseudoobscura Y chromosome lacks homology with the Y of most Drosophila species. Thus the Drosophila Y has a different evolutionary history from canonical Y chromosomes (such as the mammalian Y), and it also might have a different origin.

Natural variation of the Y chromosome suppresses sex ratio distortion and modulates testis-specific gene expression in Drosophila simulans

Branco, A T; Tao, Y; Hartl, D L; Lemos, B
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.13%
X-linked sex-ratio distorters that disrupt spermatogenesis can cause a deficiency in functional Y-bearing sperm and a female-biased sex ratio. Y-linked modifiers that restore a normal sex ratio might be abundant and favored when a X-linked distorter is present. Here we investigated natural variation of Y-linked suppressors of sex-ratio in the Winters systems and the ability of these chromosomes to modulate gene expression in Drosophila simulans. Seventy-eight Y chromosomes of worldwide origin were assayed for their resistance to the X-linked sex-ratio distorter gene Dox. Y chromosome diversity caused males to sire ∼63% to ∼98% female progeny. Genome-wide gene expression analysis revealed hundreds of genes differentially expressed between isogenic males with sensitive (high sex ratio) and resistant (low sex ratio) Y chromosomes from the same population. Although the expression of about 75% of all testis-specific genes remained unchanged across Y chromosomes, a subset of post-meiotic genes was upregulated by resistant Y chromosomes. Conversely, a set of accessory gland-specific genes and mitochondrial genes were downregulated in males with resistant Y chromosomes. The D. simulans Y chromosome also modulated gene expression in XXY females in which the Y-linked protein-coding genes are not transcribed. The data suggest that the Y chromosome might exert its regulatory functions through epigenetic mechanisms that do not require the expression of protein-coding genes. The gene network that modulates sex ratio distortion by the Y chromosome is poorly understood...

Epigenetic Effects of Polymorphic Y Chromosomes Modulate Chromatin Components, Immune Response, and Sexual Conflict

Silva, Bernardo Lemos; Hartl, Daniel L.; Branco, Alan T.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
56.09%
Genetic conflicts between sexes and generations provide a foundation for understanding the functional evolution of sex chromosomes and sexually dimorphic phenotypes. Y chromosomes of Drosophila contain multi-megabase stretches of satellite DNA repeats and a handful of protein-coding genes that are monomorphic within species. Nevertheless, polymorphic variation in heterochromatic Y chromosomes of Drosophila result in genome-wide gene expression variation. Here we show that such naturally occurring Y-linked regulatory variation (YRV) can be detected in somatic tissues and contributes to the epigenetic balance of heterochromatin/euchromatin at three distinct loci showing position-effect variegation (PEV). Moreover, polymorphic Y chromosomes differentially affect the expression of thousands of genes in XXY female genotypes in which Y-linked protein-coding genes are not transcribed. The data show a disproportionate influence of YRV on the variable expression of genes whose protein products localize to the nucleus, have nucleic-acid binding activity, and are involved in transcription, chromosome organization, and chromatin assembly. These include key components such as HP1, Trithorax-like (GAGA factor), Su(var)3–9, Brahma, MCM2, ORC2, and inner centromere protein. Furthermore...

How Do Y-Chromosomes Modulate Genome-Wide Epigenetic States: Genome Folding, Chromatin Sinks, and Gene Expression

Francisco, Flávio O.; Lemos, Bernardo
Fonte: Ivyspring International Publisher Publicador: Ivyspring International Publisher
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
55.9%
The Y chromosomes of Drosophila melanogaster and D. simulans contain only a handful of protein-coding genes, which are related to sperm mobility and reproductive fitness. Despite low or absent protein coding polymorphism, the Drosophila Y chromosome has been associated with natural phenotypic variation, including variation in the expression of hundreds to thousands of genes located on autosomes and on the X chromosome. Polymorphisms present in the large blocks of heterochromatin and consisting of differences in the amounts and kinds of sequences for satellite DNA and transposable elements may be the source of this modulation. Here we review the evidence and discuss mechanisms for global epigenetic regulation by repetitious elements in the Y chromosome. We also discuss how the discovery of this new function impacts the current knowledge about Y chromosome origin, its current dynamics, and future fate.

Bird-like sex chromosomes of platypus imply recent origin of mammal sex chromosomes

Veyrunes, F.; Waters, P.; Miethke, P.; Rens, W.; McMillan, D.; Alsop, A.; Grutzner, F.; Deakin, J.; Whittington, C.; Schatzkamer, K.; Kremitzki, C.; Graves, T.; Ferguson-Smith, M.; Warren, W.; Graves, J.
Fonte: Cold Spring Harbor Lab Press Publicador: Cold Spring Harbor Lab Press
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
46.19%
In therian mammals (placentals and marsupials), sex is determined by an XX female: XY male system, in which a gene (SRY) on the Y affects male determination. There is no equivalent in other amniotes, although some taxa (notably birds and snakes) have differentiated sex chromosomes. Birds have a ZW female: ZZ male system with no homology with mammal sex chromosomes, in which dosage of a Z-borne gene (possibly DMRT1) affects male determination. As the most basal mammal group, the egg-laying monotremes are ideal for determining how the therian XY system evolved. The platypus has an extraordinary sex chromosome complex, in which five X and five Y chromosomes pair in a translocation chain of alternating X and Y chromosomes. We used physical mapping to identify genes on the pairing regions between adjacent X and Y chromosomes. Most significantly, comparative mapping shows that, contrary to earlier reports, there is no homology between the platypus and therian X chromosomes. Orthologs of genes in the conserved region of the human X (including SOX3, the gene from which SRY evolved) all map to platypus chromosome 6, which therefore represents the ancestral autosome from which the therian X and Y pair derived. Rather, the platypus X chromosomes have substantial homology with the bird Z chromosome (including DMRT1) and to segments syntenic with this region in the human genome. Thus...

Analysis of SINE and LINE repeat content of Y chromosomes in the platypus, Ornithorhynchus anatinus

Kortschak, R.; Tsend-Ayush, E.; Grutzner, F.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
56.15%
Monotremes feature an extraordinary sex-chromosome system that consists of five X and five Y chromosomes in males. These sex chromosomes share homology with bird sex chromosomes but no homology with the therian X. The genome of a female platypus was recently completed, providing unique insights into sequence and gene content of autosomes and X chromosomes, but no Y-specific sequence has so far been analysed. Here we report the isolation, sequencing and analysis of approximately 700 kb of sequence of the non-recombining regions of Y2, Y3 and Y5, which revealed differences in base composition and repeat content between autosomes and sex chromosomes, and within the sex chromosomes themselves. This provides the first insights into repeat content of Y chromosomes in platypus, which overall show similar patterns of repeat composition to Y chromosomes in other species. Interestingly, we also observed differences between the various Y chromosomes, and in combination with timing and activity patterns we provide an approach that can be used to examine the evolutionary history of the platypus sex-chromosome chain.; Kortschak, RD; Tsend-Ayush, E. and Grutzner, F.

Identification of mediator complex 26 (Crsp7) gametologs on platypus X1 and Y5 sex chromosomes: a candidate testis-determining gene in monotremes?

Tsend-Ayush, E.; Kortschak, R.; Bernard, P.; Lim, S.; Ryan, J.; Rosenkranz, R.; Borodina, T.; Dohm, J.; Himmelbauer, H.; Harley, V.; Grutzner, F.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
56.09%
The basal lineage of monotremes features an extraordinarily complex sex chromosome system which has provided novel insights into the evolution of mammalian sex chromosomes. Recently, sequence information from autosomes, X chromosomes, and XY-shared pseudoautosomal regions has become available. However, no gene has so far been described on any of the Y chromosome-specific regions. We analyzed sequences derived from Y-specific BAC clones to identify genes with potentially malespecific function. Here, we report the identification and characterization of the mediator complex protein gametologs on platypus Y5 (Crspy). We also identified the X-chromosomal copy which unexpectedly maps to X1 (Crspx). Sequence comparison shows extensive divergence between the X and Y copy, but we found no significant positive selection on either gametolog. Expression analysis shows widespread expression of Crspx. Crspy is expressed exclusively in males with particularly strong expression in testis and kidney. Reporter gene assays to investigate whether Crspx/y can act on the recently discovered mouse Sox9 testis-specific enhancer element did reveal a modest effect together with mouse Sox9+Sf1, but showed overall no significant upregulation of the reporter gene. This is the first report of a differentiated functional male-specific gene on platypus Y chromosomes...

Construction of a highly enriched marsupial Y chromosome-specific BAC sub-library using isolated Y chromosomes

Sankovic, N.; Delbridge, M.; Grutzner, F.; Ferguson-Smith, M.; O'Brien, P.; Graves, J.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
55.94%
The Y chromosome is perhaps the most interesting element of the mammalian genome but comparative analysis of the Y chromosome has been impeded by the difficulty of assembling a shotgun sequence of the Y. BAC-based sequencing has been successful for the human and chimpanzee Y but is difficult to do efficiently for an atypical mammalian model species (Skaletsky et al. 2003, Kuroki et al. 2006). We show how Y-specific sub-libraries can be efficiently constructed using DNA amplified from microdissected or flow-sorted Y chromosomes. A Bacterial Artificial Chromosome (BAC) library was constructed from the model marsupial, the tammar wallaby (Macropus eugenii). We screened this library for Y chromosome-derived BAC clones using DNA from both a microdissected Y chromosome and a flow-sorted Y chromosome in order to create a Y chromosome-specific sub-library. We expected that the tammar wallaby Y chromosome should detect approximately 100 clones from the 2.2 times redundant library. The microdissected Y DNA detected 85 clones, 82% of which mapped to the Y chromosome and the flow-sorted Y DNA detected 71 clones, 48% of which mapped to the Y chromosome. Overall, this represented a approximately 330-fold enrichment for Y chromosome clones. This presents an ideal method for the creation of highly enriched chromosome-specific sub-libraries suitable for BAC-based sequencing of the Y chromosome of any mammalian species.; N. Sankovic...

Tamaño del genoma, heterocromatina, polimorfismo numérico y herencia de cromosomas B en razas nativas del maíz; Genome size, heterochromatin, B chromosome numerical polymorphism and B transmission rate in native races of maize

Rosato, Carmen Luisa Marcela
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //1997 SPA
Relevância na Pesquisa
46.19%
Se realizaron estudios citogenéticos en poblaciones nativas de maíz del norte argentino adaptadas a diferentes alturas de cultivo. Los mismos consistieron en: determinación del polimorfismo numérico para cromosomas B y del tamaño del genoma, caracterización de la heterocromatina mediante técnicas de bandeos cromosómicos y la relación de éstos con parámetros geográficos como la altitud. Además, se estudió la tasa de transmisión femenina de cromosomas B en una población de la raza Pisingallo. Se estudiaron 21 poblaciones (1120 individuos) cultivadas a diferentes altitudes (80-3620m). Se encontró polimorfismo numérico para cromosomas B en 19 poblaciones. Las frecuencias media de individuos portadores de cromosomas B varían entre 0 y 94%. El análisis de correlación entre el número medio de cromosomas B y la altitud indica que se correlacionan positivamente. El tamaño del genoma (contenido de ADN) fue determinado en 17 poblaciones (107 individuos). Con la finalidad de estudiar la variación del contenido de ADN en los cromosomas A (A-ADN) independientemente de la variación aportada por los Bs, ésta estimación fue llevada a cabo en plantas sin Bs. El rango de variación hallada entre las poblaciones estudiadas fue del 36% (5...

Aportes al conocimiento de los cromosomas holocíneticos de Hemiptera: estudios citogenéticos y evolutivos en especies de Cimicomorpha; Contributions to the knowledge of the holokinetic chromosomes of Hemiptera: cytogenetic and evolutionary studies in species of Cimicomorpha

Poggio, María Georgina
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2012 SPA
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El presente trabajo de Tesis Doctoral se basa en el estudio citogenético clásico, molecular y evolutivo de especies de insectos hematófagos y predadores pertenecientes a las familias Cimicidae y Reduviidae del infraorden Cimicomorpha (Hemiptera: Heteroptera), que se caracterizan por presentar cromosomas holocinéticos. Se analizó el complemento cromosómico, el desarrollo meiótico masculino, el contenido, distribución y composición de la heterocromatina y el número y la localización de los genes de ADN ribosomal en las siguientes especies: Acanthocrios furnarii 2n=10A+XY/XX (macho/hembra) y Psitticimex uritui 2n=28A+X1X2Y (macho) (Cimicidae: Haematosiphoninae); Brontostoma colossus 2n=28A+XY (macho) y B. discus 2n=34A+X1X2Y (macho) (Reduviidae: Ectrichodiinae); Microtomus lunifer 2n=26A+2m+X1X2Y (macho) (Reduviidae: Hammacerinae); Apiomerus lanipes 2n=22A+XY (macho), Atrachelus (Atrachelus) cinereus 2n=26A+XY/XX (macho/hembra), Cosmoclopius annulosus 2n=24A+X1X2X3Y/X1X1X2X2X3X3 (macho/hembra), Graptocleptes bicolor 2n=22A+XY/XX (macho/hembra) y Zelus obscuridorsis 2n=16A+XY/XX (macho/hembra) (Reduviidae: Harpactorinae); Zelurus femoralis longispinis 2n=20A+XY/X1X2Y (macho) (Reduviidae: Reduviinae); Rhodnius prolixus 2n=20A+XY/XX (macho/hembra) y Triatoma infestans 2n=20A+XY (macho) (Reduviidae: Triatominae). El análisis citogenético clásico realizado en ejemplares de A. furnarii y P. uritui demuestra que la meiosis masculina en ambas especies es aquiasmática y de tipo collochores ...

Evolution of mammalian sex chromosomes and sex determination genes: insights from monotremes.

Toledo-Flores, Deborah Fernanda
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015
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Genetic sex determination systems are generally based on the presence of differentiated sex chromosomes. Birds have a ZZ/ZW sex chromosome system in which males are ZZ and females ZW, whereas mammals have an XX/XY system with males being XY and females XX. Monotremes have an extraordinary sex chromosome system that consists of multiple sex chromosomes: 5X5Y in platypus and 5X4Y in echidna. Intriguingly, the monotreme sex chromosomes show extensive homology to the bird ZW and not to the therian XY. However, sex determination in monotremes is still a mystery; the Y-specific Sry gene that triggers male sex determination in therian mammals is absent and so far very few genes have been identified on Y chromosomes in monotremes. To gain more insights into the gene content of Y-chromosomes and to identify potential sex determination genes in the platypus a collaborative large scale transcriptomic approach led to the identification of new male specific genes including the anti-Muellerian hormone AMH that I mapped to Y₅, this makes Amhy an exciting new candidate for sex determination in monotremes. Platypus chromosome 6 is largely homologous to the therian X and therefore it represents the therian proto sex chromosome. In addition, this autosome features a large heteromorphic nucleolus organizer region (NOR) and associates with the sex chromosomes during male meiosis (Casey and Daish personal communication). I investigated chromosome 6 heteromorphism in both sexes and found a number of sex-specific characteristics related to the extent of the NOR heteromorphism...