Estudos imuno-histoquímico das proteínas p53, p16, Fhit, caspase 3 e antígeno Ki67 ; e citogenético molecular em lesões benignas e carcinoma de esôfago

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytogenetic studies in fishes of the genera Hassar, Platydoras and Opsodoras (Doradidae, Siluriformes) from Jarí and Xingú Rivers, Brazil

We studied the karyotypes of Hassar cf. orestis and an undescribed Hassar species from the Jarí River and Opsodoras ternetzi, H. orestis and Platydoras cf. costatus from the Xingú River, all with 2n = 58. Constitutive heterochromatin is located in the centromere in most metacentric pairs; in some chromosomes this banding is not present, or it is located on the whole chromosome arm or in the distal regions. The NOR is located on a single biarmed pair at a distal region of the short arm in H. cf. orestis, H. orestis and P. cf. costatus at a distal region of the long arm in O. ternetzi and at a proximal region of the long arm in the Hassar species. In all species (except for Hassar sp.) the CMA3 analysis revealed a rich G-C region coincident with the NOR. Probably inversions occurred in the NOR chromosome during the chromosomal differentiation of the Doradidae species here described.

Screening de polimorfismos e análise comparativa de alterações no número de copias do gene tp53 em gliomas

As neoplasias astrocitárias correspondem a cerca de (60%) dos tumores do sistema nervoso central, sendo que atingem principalmente adultos numa fase altamente produtiva da vida e com evoluções pouco satisfatórias apesar dos tratamentos disponíveis. Um melhor entendimento de sua biologia molecular se faz necessário na tentativa de compreender sua evolução e melhor planejar e tratamento, assim como na busca de novas terapias. Este trabalho teve como objetivo analisar modificações no gene TP53 com relação ao número de cópias e polimorfismos nos éxons de 4 a 11, considerados hotspots para mutações. Um total de 14 amostras de diferentes graus de malignidade foram analisadas por experimentos de FISH interfásico com sondas loco-específicas do gene TP53 e centroméricas para o cromossomo 17, e também pela técnica de SSCP para o screening de polimorfismos dos éxons 4-10. Foram comparados os resultados obtidos entre tumores de graus I e II (benignos) com aqueles de graus III e IV (malignos). Os resultados referentes às sondas loco-específicas (gene TP53 e centrômero do cromossomo 17) mostraram que a ocorrência de deleções ou amplificações, apesar de importantes estatisticamente em relação aos núcleos com número de marcações normais, não apresentou correlação com idade, sexo ou grau de malignação. Entretanto, as alterações foram encontradas com maior freqüência nos paciente portadores de astrocitomas de grau intermediário (III). A técnica de SSCP revelou polimorfismos nos éxons 5, 7 e 10, e apesar de não estarem associados à malignidade tumoral, os casos polimórficos corresponderam aos pacientes com menor sobrevida após tratamentos, sugerindo, uma associação entre mutações nesses éxons e uma maior agressividade tumoral.

Prevalência do gene TSPY em pacientes com anomalias do desenvolvimento sexual no Pará

Pacientes portadores de Distúrbios da Diferenciação Sexual (DDS) apresentam maior risco de desenvolver neoplasias. As alterações neoplásicas mais frequentes nestes pacientes são: o gonadoblastoma, o carcinoma in situ/tumores de células germinativas intra-tubulares não classificados. As células germinativas tipo II são as percussoras destas lesões na maioria dos casos. O gonadoblastoma é uma neoplasia benigna que não metastiza, mas pela alta prevalência e risco de evolução para as formas malignas de neoplasias gonadais, merece especial atenção. Em uma região próxima ao centrômero no braço curto do cromossomo Y, foi mapeado o gene TSPY, imputado como o gene do gonadoblastoma. Este gene expressa-se em grande quantidade nas células que constituem o gonadoblastoma. Foram avaliados 47 pacientes com DDS nos seus cariótipos e na pesquisa da prevalência do TSPY através da técnica da reação em cadeia de polimerase (PCR). As análises revelaram que 50% das pacientes com síndrome de Turner, mesmo sem o cromossomo Y, íntegro ou não, evidente no cariótipo, foram positivas para a presença do gene TSPY. Estes dados evidenciam a importância da investigação do referido gene no acompanhamento e orientação de gonadectomia em pacientes com DDS.

Mapeamento fino de qtls e polimorfismos de genes candidatos associados ao crescimento no cromossomo 1 da galinha

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inibição da divisão celular em Xanthomonas citri subsp. citri e Bacillus subtilis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

First cytogenetic characterization of the giant Amazonian catfish Brachyplatystoma filamentosum (Siluriformes, Pimelodidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Karyotype variability in tropical maize sister inbred lines and hybrids compared with KYS standard line

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

First description of the karyotype and localization of major and minor ribosomal genes in Rhoadsia altipinna Fowler, 1911 (Characiformes, Characidae) from Ecuador

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosome aberrations in lymphocyte cultures from paracoccidioidomycosis patients

Blood cell lymphocyte chromosomes from untreated (UT) and clinically-cured (CC) patients with paracoccidioidomycosis and from healthy (control) people (CO) were studied. The frequency of aneuploid cells in the UT patients was higher than in the CC and CO individuals. The frequency of metaphase cells with premature centromere division was significantly higher in the UT than in the CC and CO group. No structural aberration and no statistically significant difference in the frequency of polyploidy was observed in the three groups studied. Our findings are indicative of an aneugenic (aneuploidy-inducing) action of infection by Paracoccidioides brasiliensis.

Systemic sclerosis sine scleroderma associated with antiphospholipid syndrome

The antiphospholipid syndrome (APS) can be primary, when it occurs alone, or secondary, when it is associated with another autoimmune disease, mainly systemic lupus erythematosus and rarely other autoimmune diseases. Cases described in literature (Medline 1966 to December 2009) associate the presence of antiphospholipid antibodies with the presence of APS and systemic sclerosis (SS). Currently, however, no cases of the SS variant sine scleroderma with APS have been described. In this study, the authors describe the case of a patient with APS characterised by thrombosis of the retinal veins, in May 2006, the presence of lupus anticoagulant and an anticardiolipin IgG antibody. In May 2007, this patient developed Raynaud's phenomenon, a lack of oesophageal motility and nailfold capillaroscopy with a scleroderma pattern. The patient was positive for the anti-centromere antibody but lacked any evidence of cutaneous thickening or involvement. In summary, the authors describe the first case of a patient with APS associated with SS sine scleroderma.

Humoral autoimmune response heterogeneity in the spectrum of primary biliary cirrhosis

Objective To compare autoantibody features in patients with primary biliary cirrhosis (PBC) and individuals presenting antimitochondria antibodies (AMAs) but no clinical or biochemical evidence of disease. Methods A total of 212 AMA-positive serum samples were classified into four groups: PBC (definite PBC, n = 93); PBC/autoimmune disease (AID; PBC plus other AID, n = 37); biochemically normal (BN) individuals (n = 61); and BN/AID (BN plus other AID, n = 21). Samples were tested by indirect immunofluorescence (IIF) on rat kidney (IIF-AMA) and ELISA [antibodies to pyruvate dehydrogenase E2-complex (PDC-E2), gp-210, Sp-100, and CENP-A/B]. AMA isotype was determined by IIF-AMA. Affinity of anti-PDC-E2 IgG was determined by 8 M urea-modified ELISA. Results High-titer IIF-AMA was more frequent in PBC and PBC/AID (57 and 70 %) than in BN and BN/AID samples (23 and 19 %) (p < 0.001). Triple isotype IIF-AMA (IgA/IgM/IgG) was more frequent in PBC and PBC/AID samples (35 and 43 %) than in BN sample (18 %; p = 0.008; p = 0.013, respectively). Anti-PDC-E2 levels were higher in PBC (mean 3.82; 95 % CI 3.36–4.29) and PBC/AID samples (3.89; 3.15–4.63) than in BN (2.43; 1.92–2.94) and BN/AID samples (2.52; 1.54–3.50) (p < 0.001). Anti-PDC-E2 avidity was higher in PBC (mean 64.5 %; 95 % CI 57.5–71.5 %) and PBC/AID samples (66.1 %; 54.4–77.8 %) than in BN samples (39.2 %; 30.9–37.5 %) (p < 0.001). PBC and PBC/AID recognized more cell domains (mitochondria, nuclear envelope, PML/sp-100 bodies, centromere) than BN (p = 0.008) and BN/AID samples (p = 0.002). Three variables were independently associated with established PBC: high-avidity anti-PDC-E2 (OR 4.121; 95 % CI 2.118–8.019); high-titer IIF-AMA (OR 4.890; 2.319–10.314); antibodies to three or more antigenic cell domains (OR 9.414; 1.924–46.060). Conclusion The autoantibody profile was quantitatively and qualitatively more robust in definite PBC as compared with AMA-positive biochemically normal individuals.

Structural and functional analysis of centromeric chromatin

Animal neocentromeres are defined as ectopic centromeres that have formed in non-centromeric locations and avoid some of the features, like the DNA satellite sequence, that normally characterize canonical centromeres. Despite this, they are stable functional centromeres inherited through generations. The only existence of neocentromeres provide convincing evidence that centromere specification is determined by epigenetic rather than sequence-specific mechanisms. For all this reasons, we used them as simplified models to investigate the molecular mechanisms that underlay the formation and the maintenance of functional centromeres. We collected human cell lines carrying neocentromeres in different positions. To investigate the region involved in the process at the DNA sequence level we applied a recent technology that integrates Chromatin Immuno-Precipitation and DNA microarrays (ChIP-on-chip) using rabbit polyclonal antibodies directed against CENP-A or CENP-C human centromeric proteins. These DNA binding-proteins are required for kinetochore function and are exclusively targeted to functional centromeres. Thus, the immunoprecipitation of DNA bound by these proteins allows the isolation of centromeric sequences, including those of the neocentromeres. Neocentromeres arise even in protein-coding genes region. We further analyzed if the increased scaffold attachment sites and the corresponding tighter chromatin of the region involved in the neocentromerization process still were permissive or not to transcription of within encoded genes. Centromere repositioning is a phenomenon in which a neocentromere arisen without altering the gene order, followed by the inactivation of the canonical centromere, becomes fixed in population. It is a process of chromosome rearrangement fundamental in evolution, at the bases of speciation. The repeat-free region where the neocentromere initially forms, progressively acquires extended arrays of satellite tandem repeats that may contribute to its functional stability. In this view our attention focalized to the repositioned horse ECA11 centromere. ChIP-on-chip analysis was used to define the region involved and SNPs studies, mapping within the region involved into neocentromerization, were carried on. We have been able to describe the structural polymorphism of the chromosome 11 centromeric domain of Caballus population. That polymorphism was seen even between homologues chromosome of the same cells. That discovery was the first described ever. Genomic plasticity had a fundamental role in evolution. Centromeres are not static packaged region of genomes. The key question that fascinates biologists is to understand how that centromere plasticity could be combined to the stability and maintenance of centromeric function. Starting from the epigenetic point of view that underlies centromere formation, we decided to analyze the RNA content of centromeric chromatin. RNA, as well as secondary chemically modifications that involve both histones and DNA, represents a good candidate to guide somehow the centromere formation and maintenance. Many observations suggest that transcription of centromeric DNA or of other non-coding RNAs could affect centromere formation. To date has been no thorough investigation addressing the identity of the chromatin-associated RNAs (CARs) on a global scale. This prompted us to develop techniques to identify CARs in a genome-wide approach using high-throughput genomic platforms. The future goal of this study will be to focalize the attention on what strictly happens specifically inside centromere chromatin.

Holocentric chromosomes: convergent evolution, meiotic adaptations, and genomic analysis

In most eukaryotes, the kinetochore protein complex assembles at a single locus termed the centromere to attach chromosomes to spindle microtubules. Holocentric chromosomes have the unusual property of attaching to spindle microtubules along their entire length. Our mechanistic understanding of holocentric chromosome function is derived largely from studies in the nematode Caenorhabditis elegans, but holocentric chromosomes are found over a broad range of animal and plant species. In this review, we describe how holocentricity may be identified through cytological and molecular methods. By surveying the diversity of organisms with holocentric chromosomes, we estimate that the trait has arisen at least 13 independent times (four times in plants and at least nine times in animals). Holocentric chromosomes have inherent problems in meiosis because bivalents can attach to spindles in a random fashion. Interestingly, there are several solutions that have evolved to allow accurate meiotic segregation of holocentric chromosomes. Lastly, we describe how extensive genome sequencing and experiments in nonmodel organisms may allow holocentric chromosomes to shed light on general principles of chromosome segregation.

Higher frequency of chromosomal aberrations in ovarian endometriosis compared to extragonadal endometriosis: A possible link to endometrioid adenocarcinoma

Endometriosis may progress to invasive endometrioid adenocarcinoma, particularly in the ovary. Up to now, little is known of the molecular mechanisms possibly involved in the malignant transformation of endometriosis. Therefore, in this study, extragonadal endometriosis (n = 10), ovarian endometriosis without malignancy (n = 10), ovarian endometriosis with direct transition into endometrioid adenocarcinoma (n = 8), and normal endometrium (n = 12) were investigated for numerical chromosomal aberrations by fluorescence in situ hybridization using centromere enumeration probes. The proportions of cells with aneusomies were semiquantitatively assessed. Trisomies 1 and 7, and monosomies 9 and 17 were found in endometriosis, ovarian endometrioid adenocarcinoma, and normal endometrium. The proportions of aneusomic cells were significantly higher in ovarian endometrioid carcinoma compared with ovarian endometriosis (P < 0.001), and in ovarian endometriosis compared with extragonadal endometriosis and normal endometrium (P < 0.001). The data provide new evidence of a common lineage of endometriosis and ovarian endometrioid carcinoma. The higher frequency of chromosomal aberrations in endometrioid carcinoma than in endometriosis may reflect an expansion of aberrant cell clones already present in endometriosis during the progression to cancer. The higher frequency of chromosomal aberrations in ovarian endometriosis than in extragonadal endometriosis suggests a role of the ovarian stromal milieu in the induction of genetic changes, which may eventually lead to invasive cancer.