Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.517
Filtrar
1.
Mol Genet Genomics ; 295(1): 221-231, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31641857

RESUMO

The Xinjiang Uyghur Autonomous Region of China (XUARC) with 47 ethnic groups is a very colorful ethnic region of China, harboring abundant genetic and cultural diversity. The Kazakhs are the third largest ethnic group (7.02%) after Uyghur (46.42%) and Han (38.99%) in Xinjiang, but their genetic diversity and forensic characterization are poorly understood. In the current study, we genotyped 15 autosomal short tandem repeat (STR) loci and ten Y-STRs in 889 individuals (659 male and 230 female) collected from Kazak population of the Ili Kazak Autonomous Prefecture using AGCU Expressmarker 16 and 10Y-STR Kit (EX16 + 10Y). For autosomal STRs, we observed a total of 174 different alleles ranging from 6 to 34.2 repeat units and FGA showed the greatest power of discrimination (20 alleles) in Ili Kazakh population. We have not observed departures from Hardy-Weinberg equilibrium (HWE) after sequential Bonferroni correction and only found a minimal departure from linkage equilibrium (LE) for a very small number of pairwise combinations of loci. The combined power of exclusion (CPE) was 0.99999998395 and combined power of discrimination (CPD) was 99.999999999999999798%. For Y-STRs, we observed a total of 496 different haplotypes in these ten Y-STR loci. The gene diversities ranged from 0.5023 (DYS391) to 0.8357 (DYS385a/b). The overall haplotype diversity (GD) was 0.9985 with random matching probability (RMP) of 0.0015. The results of population genetic analysis based on both autosomal and Y-chromosome STRs demonstrated that the genetic affinity among populations is generally consistent with ethnic, linguistic, and continental geographical classifications.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Cromossomos/genética , Polimorfismo Genético/genética , Alelos , Feminino , Frequência do Gene/genética , Testes Genéticos/métodos , Genética Populacional/métodos , Haplótipos/genética , Humanos , Masculino , Repetições de Microssatélites/genética , Filogenia
2.
Zool Res ; 41(1): 94-96, 2020 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-31840950

RESUMO

Many functional elements associated with traits and diseases are located in non-coding regions and act on distant target genes via chromatin looping and folding, making it difficult for scientists to reveal the genetic regulatory mechanisms. Capture Hi-C is a newly developed chromosome conformation capture technology based on hybridization capture between probes and target genomic regions. It can identify interactions among target loci and all other loci in a genome with low cost and high resolution. Here, we developed CaptureProbe, a user-friendly, graphical Java tool for the design of capture probes across a range of target sites or regions. Numerous parameters helped to achieve and optimize the designed probes. Design testing of CaptureProbe showed high efficiency in the design success ratio of target loci and probe specificity. Hence, this program will help scientists conduct genome spatial interaction research. CaptureProbe and source code are available at https://sourceforge.net/projects/captureprobe/.


Assuntos
Cromossomos/genética , Sondas de DNA/genética , Genômica/métodos , Software , Animais , Humanos
3.
BMC Bioinformatics ; 20(Suppl 20): 641, 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31842730

RESUMO

BACKGROUND: Many cancer genomes are extensively rearranged with highly aberrant chromosomal karyotypes. Structural and copy number variations in cancer genomes can be determined via abnormal mapping of sequenced reads to the reference genome. Recently it became possible to reconcile both of these types of large-scale variations into a karyotype graph representation of the rearranged cancer genomes. Such a representation, however, does not directly describe the linear and/or circular structure of the underlying rearranged cancer chromosomes, thus limiting possible analysis of cancer genomes somatic evolutionary process as well as functional genomic changes brought by the large-scale genome rearrangements. RESULTS: Here we address the aforementioned limitation by introducing a novel methodological framework for recovering rearranged cancer chromosomes from karyotype graphs. For a cancer karyotype graph we formulate an Eulerian Decomposition Problem (EDP) of finding a collection of linear and/or circular rearranged cancer chromosomes that are determined by the graph. We derive and prove computational complexities for several variations of the EDP. We then demonstrate that Eulerian decomposition of the cancer karyotype graphs is not always unique and present the Consistent Contig Covering Problem (CCCP) of recovering unambiguous cancer contigs from the cancer karyotype graph, and describe a novel algorithm CCR capable of solving CCCP in polynomial time. We apply CCR on a prostate cancer dataset and demonstrate that it is capable of consistently recovering large cancer contigs even when underlying cancer genomes are highly rearranged. CONCLUSIONS: CCR can recover rearranged cancer contigs from karyotype graphs thereby addressing existing limitation in inferring chromosomal structures of rearranged cancer genomes and advancing our understanding of both patient/cancer-specific as well as the overall genetic instability in cancer.


Assuntos
Cromossomos/genética , Rearranjo Gênico/genética , Cariótipo , Neoplasias/genética , Algoritmos , Sequência de Bases , Genoma , Humanos
4.
Cytogenet Genome Res ; 159(4): 208-214, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31846969

RESUMO

The karyotypes and other chromosomal markers of 4 catfish species, namely Lasiancistrus schomburgkii, Lasiancistrus sp., Araichthysloro, and Megalancistrus sp., members of a taxonomically complex and speciose tribe of catfishes Ancistrini, Hypostominae, were examined using conventional (Giemsa staining, Ag-NOR, and C-banding) and molecular cytogenetic protocols (FISH) and DNA barcoding. In L. schomburgkii, Lasiancistrus sp., and A.loro a diploid number 2n = 54 was observed, with karyotypes composed of 28m + 16sm + 10st, 36m + 12sm + 6st chromosomes, while Megalancistrus sp. had 2n = 52, with the karyotype composed of 28m + 16sm + 8st chromosomes. The Ag-NOR phenotypes were simple in all 4 species, which was confirmed by FISH with an 18S rDNA probe. However, the positive 5S rDNA sites varied among species: 2 chromosome pairs in L. schomburgkii, Lasiancistrus sp., and A. loro, and only 1 pair in Megalancistrus sp. The blocks of constitutive heterochromatin were poorly visible in the pericentromeric and telomeric regions of most chromosomes of the examined species by C-banding. The genetic distance analysis, based on mtDNA COI gene sequences (DNA barcoding), confirmed the species as 4 taxonomic units. Ours and other published data indicate that karyotype differentiation among Ancistrini is complex and divergent and indicates the occurrence of common chromosomal rearrangements, such as pericentric inversions conserving the diploid number, and other rearrangements that are more frequent in some genera, such as centric fusions in Ancistrus.


Assuntos
Peixes-Gato/genética , Animais , Inversão Cromossômica/genética , Cromossomos/genética , Citogenética/métodos , DNA Ribossômico/genética , Diploide , Feminino , Heterocromatina/genética , Cariótipo , Masculino , Filogenia , Telômero/genética
5.
Cytogenet Genome Res ; 159(4): 169-181, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31846971

RESUMO

Here, we report the findings of a 25-year cytogenetic follow-up study on a male patient who received 2 rounds of radioiodine treatment within a span of 26 months (1.78 GBq in 1992 and 14.5 GBq in 1994). The patient was 34 years old with a body mass index of 25 at the time of the first radioiodine treatment. Multicolor FISH and multicolor banding (mBAND) techniques performed on the patient detected inter- and intrachromosomal exchanges. Although the frequency of chromosome translocations remained essentially the same as reported in our earlier study (0.09/cell), the percentage of reciprocal (balanced) translocations increased from 54.38 to 80.30% in the current study. In addition to simple chromosome translocations, complex exchanges (0.29%) involving more than 2 chromosomes were detected for the first time in this patient. Strikingly, a clonal translocation involving chromosomes 14 and 15, t(14p;15q), was found in 7 of the 677 cells examined (1.03%). The presence of complex and clonal translocations indicates the onset of chromosomal instability induced by internal radioiodine exposure. mBAND analysis using probes specific for chromosomes 1, 2, 4, 5, and 10 revealed 5 inversions in a total of 717 cells (0.69%), and this inversion frequency is several-fold higher than the baseline frequency reported in healthy individuals using the classical G-banding technique. Collectively, our study suggests that stable chromosome aberrations such as translocations and inversions can be useful not only for retrospective biodosimetry but also for long-term monitoring of chromosomal instability caused by past radioiodine exposure.


Assuntos
Cromossomos/genética , Cromossomos/efeitos da radiação , Radioisótopos do Iodo/efeitos adversos , Translocação Genética/genética , Translocação Genética/efeitos da radiação , Adulto , Aberrações Cromossômicas/efeitos da radiação , Bandeamento Cromossômico/métodos , Inversão Cromossômica/genética , Inversão Cromossômica/efeitos da radiação , Citogenética/métodos , Seguimentos , Humanos , Masculino
6.
Cytogenet Genome Res ; 159(4): 201-207, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31865337

RESUMO

Genetic factors are responsible for 15% of male infertility conditions. Numerical and structural chromosomal anomalies (related to the Y chromosome or to the autosomes) are validated genetic factors leading to spermatogenic quantitative defects with a frequency depending on the severity of the phenotype. The most frequent structural chromosomal rearrangements of autosomes are translocations and inversions, whereas dicentric chromosomes involving autosomes are rare. We report a man bearing a pseudodicentric chromosome (9;21) and presenting with oligozoospermia. Extensive cytogenetic analyses were necessary to determine the precise nature of the derivative chromosome and to discount the presence of interstitial telomeric sequences. Defects in spermatogenesis and abnormal segregation at meiosis for existing spermatozoa are proposed and are the likely cause of the reproductive phenotype of the patient.


Assuntos
Cromossomos/genética , Oligospermia/genética , Translocação Genética/genética , Adulto , Inversão Cromossômica/genética , Humanos , Masculino , Espermatogênese/genética , Espermatozoides/fisiologia
7.
Zhonghua Fu Chan Ke Za Zhi ; 54(12): 808-814, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31874470

RESUMO

Objective: To evaluate the application of combinatorial probe anchor synthesis (cPAS)-based high-throughput low coverage whole genome sequencing in chromosomal aberration detection in spontaneous miscarriage. Methods: From September 2015 to May 2017, spontaneous miscarriage samples were collected from Inner Mongolia Maternal and Child Health Care Hospital. Those samples were further analyzed with two independent methods, fluorescence in situ hybridization (FISH) and low coverage whole genome sequencing on the BGISEQ-500 high-throughput platform. The performance of low coverage whole genome sequencing was assessed by comparing to FISH results. Results: In 595 spontaneous miscarried specimens, low coverage whole genome sequencing revealed 144 cases (24.2%, 144/595) chromosomal abnormalities, of which a subset of 137 cases (23.0%, 137/595) were detected as aneuploidies, 2 cases (0.3%, 2/595) as mosaicisms and 5 cases (0.8%, 5/595) as copy number variation (≥5 Mb). Conclusion: cPAS-based high-throughput low coverage whole genome sequencing is a reliable method in detecting chromosomal aberrations inspontaneous abortion tissues, including chromosome aneuploidies, mosaicisms and copy number variation (≥5 Mb).


Assuntos
Aborto Espontâneo/genética , Aberrações Cromossômicas/estatística & dados numéricos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Criança , China , Aberrações Cromossômicas/embriologia , Cromossomos/genética , DNA/genética , Variações do Número de Cópias de DNA/genética , Feminino , Humanos , Hibridização in Situ Fluorescente , Gravidez , Sequenciamento Completo do Genoma/métodos
8.
Genes Dev ; 33(23-24): 1688-1701, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31727772

RESUMO

Human nucleolar organizer regions (NORs), containing ribosomal gene (rDNA) arrays, are located on the p-arms of acrocentric chromosomes (HSA13-15, 21, and 22). Absence of these p-arms from genome references has hampered research on nucleolar formation. Previously, we assembled a distal junction (DJ) DNA sequence contig that abuts rDNA arrays on their telomeric side, revealing that it is shared among the acrocentrics and impacts nucleolar organization. To facilitate inclusion into genome references, we describe sequencing the DJ from all acrocentrics, including three versions of HSA21, ∼3 Mb of novel sequence. This was achieved by exploiting monochromosomal somatic cell hybrids containing single human acrocentric chromosomes with NORs that retain functional potential. Analyses revealed remarkable DJ sequence and functional conservation among human acrocentrics. Exploring chimpanzee acrocentrics, we show that "DJ-like" sequences and abutting rDNA arrays are inverted as a unit in comparison to humans. Thus, rDNA arrays and linked DJs represent a conserved functional locus. We provide direct evidence for exchanges between heterologous human acrocentric p-arms, and uncover extensive structural variation between chromosomes and among individuals. These findings lead us to revaluate the molecular definition of NORs, identify novel genomic structural variation, and provide a rationale for the distinctive chromosomal organization of NORs.


Assuntos
Cromossomos/química , Cromossomos/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Região Organizadora do Nucléolo/química , Região Organizadora do Nucléolo/genética , Animais , Sequência de Bases , Linhagem Celular , Sequência Conservada/genética , Estruturas Genéticas/genética , Variação Genética , Humanos , Células Híbridas , Camundongos , Pan troglodytes/genética
10.
J Cancer Res Clin Oncol ; 145(12): 2901-2910, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31654122

RESUMO

INTRODUCTION: The nuclear pore complex is comprised of approximately 30 proteins named nucleoporins (Nups) and tightly regulates nucleocytoplasmic transport of macromolecules across the nuclear membrane. Genetic alterations in many NUP genes are associated with many human maladies, such as neurological disease, autoimmune disorders and cancer. METHODS: We reviewed the status quo of recent advancement of the knowledge of oncogenic role of nucleoporins in human carcinogenesis, focusing on major non-hematological malignancies in the recent literature. Both clinical study-derived and experiment-based reports were critically reviewed. We have also discussed the potential of nucleoporins as novel cancer biomarkers and promising therapeutic target against human malignancies. RESULTS: Several Nups such as Nup53, Nup88, Nup98, Nup160 and Nup214 modulated a plethora of cellular and physiological pathways involved in tumorigenesis such as GSK3ß-Snail, Wnt/ß-Catenin and RanGap1/RanBP2 signaling axes, DNA damage response, resistance to apoptosis and chemotherapy. CONCLUSION: Although classically, majority of studies have shown oncogenic roles of nucleoporins as genetic fusion partners in several types of leukemia, emerging evidence suggests that nucleoporins also modulate many cellular signaling pathways that are associated with several major non-hematological malignancies, such as carcinomas of skin, breast, lung, prostate and colon. Hence, nucleoporins are emerging as novel therapeutic targets in human tumors.


Assuntos
Cromossomos/genética , Fusão Gênica/genética , Neoplasias/genética , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Oncogenes/genética , Translocação Genética/genética , Animais , Humanos
11.
Cytogenet Genome Res ; 159(1): 48-53, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31610539

RESUMO

Visualizing the spatiotemporal organization of the genome will improve our understanding of how chromatin structure and function are intertwined. Here, we describe a further development of the CRISPR/Cas9-based RNA-guided endonuclease-in situ labeling (RGEN-ISL) method. RGEN-ISL allowed the differentiation between vertebrate-type (TTAGGG)n and Arabidopsis-type (TTTAGGG)n telomere repeats. Using maize as an example, we established a combination of RGEN-ISL, immunostaining, and EdU labeling to visualize in situ specific repeats, histone marks, and DNA replication sites, respectively. The effects of the non-denaturing RGEN-ISL and standard denaturing FISH on the chromatin structure were compared using super-resolution microscopy. 3D structured illumination microscopy revealed that denaturation and acetic acid fixation impaired and flattened the chromatin. The broad range of adaptability of RGEN-ISL to different combinations of methods has the potential to advance the field of chromosome biology.


Assuntos
Amaryllidaceae/genética , Arabidopsis/genética , Sistemas CRISPR-Cas/genética , Replicação do DNA/genética , Zea mays/genética , Cromatina/metabolismo , Cromossomos/genética , DNA de Plantas/genética , Endonucleases/genética , Hibridização in Situ Fluorescente/métodos , RNA Guia/genética , Telômero/genética
12.
Cytogenet Genome Res ; 159(2): 88-96, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31593945

RESUMO

The bush dog (Speothos venaticus, 2n = 74) is a near threatened species taxonomically classified among South American canids. We revised the bush dog karyotype and performed a comparative sequence analysis of satellite and satellite-like DNAs in 6 canids: the bush dog, domestic dog (Canis familiaris, 2n = 78), grey wolf (C. lupus, 2n = 78), Chinese raccoon dog (Nyctereutes procyonoides procyonoides, 2n = 54+B), red fox (Vulpes vulpes, 2n = 34+B), and arctic fox (V. lagopus, 2n = 48-50) to specify the species position among Canidae. Using FISH with painting and BAC probes, we found that the distribution of canid evolutionarily conserved chromosome segments in the bush dog karyotype is similar to that of the domestic dog and grey wolf. The bush dog karyotype differs by 2 acrocentric chromosome pairs formed by tandem fusions of the canine (29;34) and (26;35) orthologues. An interstitial signal of the telomeric probe was observed in the (26;35) fusion site in the bush dog indicating a recent evolutionary origin of this rearrangement. Sequences and hybridisation patterns of satellite DNAs were compared, and a phylogenetic tree of the 6 canid species was constructed which confirmed the bush dog position close to the wolf-like canids, and apart from the raccoon dog and foxes.


Assuntos
Cromossomos/genética , DNA Satélite/genética , Animais , Bandeamento Cromossômico/métodos , Cães , Evolução Molecular , Raposas/genética , Cariótipo , Cariotipagem/métodos , Filogenia , Lobos/genética
13.
BMC Genomics ; 20(1): 764, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31640542

RESUMO

BACKGROUND: A complete understanding of the genetic basis for sexual determination and differentiation is necessary in order to implement efficient breeding schemes at early stages of development. Atlantic salmon belongs to the family Salmonidae of fishes and represents a species of great commercial value. Although the species is assumed to be male heterogametic with XY sex determination, the precise genetic basis of sexual development remains unclear. The complexity is likely associated to the relatively recent salmonid specific whole genome duplication that may be responsible for certain genome instability. This instability together with the capacity of the sex-determining gene to move across the genome as reported by previous studies, may explain that sexual development genes are not circumscribed to the same chromosomes in all members of the species. In this study, we have used a 220 K SNP panel developed for Atlantic salmon to identify the chromosomes explaining the highest proportion of the genetic variance for sex as well as candidate regions and genes associated to sexual development in this species. RESULTS: Results from regional heritability analysis showed that the chromosomes explaining the highest proportion of variance in these populations were Ssa02 (heritability = 0.42, SE = 0.12) and Ssa21 (heritability = 0.26, SE = 0.11). After pruning by linkage disequilibrium, genome-wide association analyses revealed 114 SNPs that were significantly associated with sex, being Ssa02 the chromosome containing a greatest number of regions. Close examination of the candidate regions evidenced important genes related to sex in other species of Class Actinopterygii, including SDY, genes from family SOX, RSPO1, ESR1, U2AF2A, LMO7, GNRH-R, DND and FIGLA. CONCLUSIONS: The combined results from regional heritability analysis and genome-wide association have provided new advances in the knowledge of the genetic regulation of sex determination in Atlantic salmon, supporting that Ssa02 is the candidate chromosome for sex in this species and suggesting an alternative population lineage in Spanish wild populations according to the results from Ssa21.


Assuntos
Genoma/genética , Salmo salar/genética , Processos de Determinação Sexual/genética , Animais , Mapeamento Cromossômico , Cromossomos/genética , Feminino , Ligação Genética , Estudo de Associação Genômica Ampla , Desequilíbrio de Ligação , Masculino , Polimorfismo de Nucleotídeo Único/genética
14.
Nucleic Acids Res ; 47(19): 10166-10180, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31665745

RESUMO

HORMA domain-containing proteins such as Hop1 play crucial regulatory roles in various chromosomal functions. Here, we investigated roles of the fission yeast Hop1 in the formation of recombination-initiating meiotic DNA double strand breaks (DSBs). Meiotic DSB formation in fission yeast relies on multiple protein-protein interactions such as the one between the chromosome axial protein Rec10 and the DSB-forming complex subunit Rec15. Chromatin immunoprecipitation sequencing demonstrated that Hop1 is colocalized with both Rec10 and Rec15, and we observed physical interactions of Hop1 to Rec15 and Rec10. These results suggest that Hop1 promotes DSB formation by interacting with both axis components and the DSB-forming complex. We also show that Hop1 binding to DSB hotspots requires Rec15 and Rec10, while Hop1 axis binding requires Rec10 only, suggesting that Hop1 is recruited to the axis via Rec10, and to hotspots by hotspot-bound Rec15. Furthermore, we introduced separation-of-function Rec10 mutations, deficient for interaction with either Rec15 or Hop1. These single mutations and hop1Δ conferred only partial defects in meiotic recombination, while the combining the Rec15-binding-deficient rec10 mutation with hop1Δ synergistically reduced meiotic recombination, at least at a model hotspot. Taken together, Hop1 likely functions as a stabilizer for Rec15-Rec10 interaction to promote DSB formation.


Assuntos
Proteínas de Ligação a DNA/genética , Recombinação Homóloga/genética , Proteínas de Schizosaccharomyces pombe/genética , Cromossomos/genética , Quebras de DNA de Cadeia Dupla , Meiose/genética , Mutação , Domínios Proteicos/genética , Schizosaccharomyces/genética , Complexo Sinaptonêmico/genética
15.
PLoS Genet ; 15(9): e1008320, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31513569

RESUMO

In all kingdoms of life, DNA is used to encode hereditary information. Propagation of the genetic material between generations requires timely and accurate duplication of DNA by semiconservative replication prior to cell division to ensure each daughter cell receives the full complement of chromosomes. DNA synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset. Here, we discuss commonalities and differences in replication origin organization and recognition in the three domains of life.


Assuntos
Replicação do DNA/genética , Replicação do DNA/fisiologia , Origem de Replicação/genética , Evolução Biológica , Divisão Celular/genética , Cromossomos/genética , Evolução Molecular , Replicon/genética
16.
PLoS Genet ; 15(9): e1008389, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31525198

RESUMO

Gene expression is subject to stochastic noise, but to what extent and by which means such stochastic variations are coordinated among different genes are unclear. We hypothesize that neighboring genes on the same chromosome co-fluctuate in expression because of their common chromatin dynamics, and verify it at the genomic scale using allele-specific single-cell RNA-sequencing data of mouse cells. Unexpectedly, the co-fluctuation extends to genes that are over 60 million bases apart. We provide evidence that this long-range effect arises in part from chromatin co-accessibilities of linked loci attributable to three-dimensional proximity, which is much closer intra-chromosomally than inter-chromosomally. We further show that genes encoding components of the same protein complex tend to be chromosomally linked, likely resulting from natural selection for intracellular among-component dosage balance. These findings have implications for both the evolution of genome organization and optimal design of synthetic genomes in the face of gene expression noise.


Assuntos
Regulação da Expressão Gênica/genética , Expressão Gênica/genética , Ligação Genética/genética , Animais , Cromatina/genética , Mapeamento Cromossômico/métodos , Cromossomos/genética , Bases de Dados Genéticas , Evolução Molecular , Genoma/genética , Genômica/métodos , Humanos , Mamíferos/genética , Camundongos , Seleção Genética , Processos Estocásticos
17.
Cytogenet Genome Res ; 159(1): 32-38, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31542782

RESUMO

Despite the variation observed in the diploid chromosome number of storks (Ciconiiformes, Ciconiidae), from 2n = 52 to 2n = 78, most reports have relied solely on analyses by conventional staining. As most species have similar macrochromosomes, some authors propose that karyotype evolution involves mainly fusions between microchromosomes, which are highly variable in species with different diploid numbers. In order to verify this hypothesis, in this study, the karyotypes of 2 species of storks from South America with different diploid numbers, the jabiru (Jabiru mycteria, 2n = 56) and the maguary stork (Ciconia maguary, 2n = 72), were analyzed by chromosome painting using whole chromosome probes from the macrochromosomes of Gallus gallus (GGA) and Leucopternis albicollis (LAL). The results revealed that J. mycteria and C. maguary share synteny within chromosome pairs 1-9 and Z. The syntenies to the macrochromosomes of G. gallus are conserved, except for GGA4, which is homologous to 2 different pairs, as in most species of birds. A fusion of GGA8 and GGA9 was observed in both species. Additionally, chromosomes corresponding to GGA4p and GGA6 are fused to other segments that did not hybridize to any of the macrochromosome probes used, suggesting that these segments correspond to microchromosomes. Hence, our data corroborate the proposed hypothesis that karyotype evolution is based on fusions involving microchromosomes. In view of the morphological constancy of the macrochromosome pairs in most Ciconiidae, we propose a putative ancestral karyotype for the family, including the GGA8/GGA9 fusion, and a diploid number of 2n = 78. The use of probes for microchromosome pairs should be the next step in identifying other synapomorphies that may help to clarify the phylogeny of this family.


Assuntos
Aves/genética , Coloração Cromossômica/veterinária , Cromossomos/genética , Variação Genética/genética , Cariótipo , Animais , Brasil , Diploide , Evolução Molecular , Feminino , Filogenia
18.
Parasitol Res ; 118(10): 2789-2800, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31485863

RESUMO

An original cytogenetic study combining classical karyotype analysis and modern fluorescence in situ hybridization using telomeric (TTAGGG)n and ribosomal sequences (18S rDNA) was performed in Khawia abbottinae (Cestoda, Caryophyllidea), a parasite of Chinese false gudgeon (Abbottina rivularis) from China. Analyses based on conventional Giemsa staining, DAPI, YOYO-1 dye, and silver (Ag) staining were also carried out. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n=5m + 3t). Constitutive heterochromatin was mainly positioned at pericentromeric regions, and telomeric sequences (TTAGGG)n were restricted to the end of all chromosomes. In mitotic preparations stained with Giemsa, both homologues of chromosome pair 4 showed a distinct secondary constriction. FISH with rDNA probe confirmed that this secondary constriction contains a nucleolar organizer region (NOR). The process of spermatocyte meiosis and the dynamics of nucleolus degradation in dividing cell were scrutinized. The present study and its results enhance the limited knowledge on basic karyotype characteristics and 18S rDNA clusters location in caryophyllidean tapeworms.


Assuntos
Cestoides/genética , Cromossomos/genética , DNA Ribossômico/genética , Telômero/genética , Animais , Cestoides/classificação , Cestoides/isolamento & purificação , China , Cyprinidae/genética , DNA de Helmintos/genética , Proteínas de Helminto/genética , Heterocromatina/genética , Hibridização in Situ Fluorescente , Cariótipo , Cariotipagem , Ribossomos/genética
19.
Nucleic Acids Res ; 47(18): 9666-9684, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31392335

RESUMO

Break induced replication (BIR) is a double strand break repair pathway that can promote genetic instabilities similar to those observed in cancer. Instead of a replication fork, BIR is driven by a migration bubble where asynchronous synthesis between leading and lagging strands leads to accumulation of single-stranded DNA (ssDNA) that promotes mutation. However, the details of the mechanism of mutagenesis, including the identity of the participating proteins, remain unknown. Using yeast as a model, we demonstrate that mutagenic ssDNA is formed at multiple positions along the BIR track and that Pol ζ is responsible for the majority of both spontaneous and damage-induced base substitutions during BIR. We also report that BIR creates a potent substrate for APOBEC3A (A3A) cytidine deaminase that can promote formation of mutation clusters along the entire track of BIR. Finally, we demonstrate that uracil glycosylase initiates the bypass of DNA damage induced by A3A in the context of BIR without formation of base substitutions, but instead this pathway frequently leads to chromosomal rearrangements. Together, the expression of A3A during BIR in yeast recapitulates the main features of APOBEC-induced kataegis in human cancers, suggesting that BIR might represent an important source of these hyper-mutagenic events.


Assuntos
Cromossomos/genética , Citidina Desaminase/genética , Reparo do DNA/genética , Proteínas/genética , Recombinação Genética , Quebras de DNA de Cadeia Dupla , Dano ao DNA/genética , Replicação do DNA/genética , DNA de Cadeia Simples/genética , Humanos , Mutagênese/genética , Mutação , Saccharomyces cerevisiae/genética , Sequenciamento Completo do Genoma
20.
Nucleic Acids Res ; 47(18): 9696-9707, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31400115

RESUMO

Ubiquitous Structural Maintenance of Chromosomes (SMC) complexes use a proteinaceous ring-shaped architecture to organize and individualize chromosomes, thereby facilitating chromosome segregation. They utilize cycles of adenosine triphosphate (ATP) binding and hydrolysis to transport themselves rapidly with respect to DNA, a process requiring protein conformational changes and multiple DNA contact sites. By analysing changes in the architecture and stoichiometry of the Escherichia coli SMC complex, MukBEF, as a function of nucleotide binding to MukB and subsequent ATP hydrolysis, we demonstrate directly the formation of dimer of MukBEF dimer complexes, dependent on dimeric MukF kleisin. Using truncated and full length MukB, in combination with MukEF, we show that engagement of the MukB ATPase heads on nucleotide binding directs the formation of dimers of heads-engaged dimer complexes. Complex formation requires functional interactions between the C- and N-terminal domains of MukF with the MukB head and neck, respectively, and MukE, which organizes the complexes by stabilizing binding of MukB heads to MukF. In the absence of head engagement, a MukF dimer bound by MukE forms complexes containing only a dimer of MukB. Finally, we demonstrate that cells expressing MukBEF complexes in which MukF is monomeric are Muk-, with the complexes failing to associate with chromosomes.


Assuntos
Proteínas Cromossômicas não Histona/química , Proteínas de Escherichia coli/genética , Proteínas Repressoras/genética , Proteínas Cromossômicas não Histona/genética , Cromossomos/química , Cromossomos/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Escherichia coli/química , Escherichia coli/genética , Proteínas de Escherichia coli/química , Complexos Multiproteicos/química , Complexos Multiproteicos/genética , Ligação Proteica , Proteínas Repressoras/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA