RESUMEN
The genus Ctenomys has been widely used in karyotype evolution studies due to the variation in their diploid numbers. Ctenomys minutus is characterized by intraspecific variation in diploid number (2n = 42, 46, 48, and 50), which makes it an interesting model to investigate genomic rearrangements mechanisms that could lead to different cytotypes in this species. Thereupon, it has been already shown that DNA methylation may participate in chromosome structure. Therefore, we aimed to investigate whether telomeres and global DNA methylation had a role in the genome rearrangements that led to this variation in C. minutus. We also realized an analysis for the presence of intrachromosomal telomeric repeats (ITRs) by fluorescence in situ hybridization. Our study demonstrated that neither telomere length nor DNA methylation had significant differences among the cytotypes. However, if only females were considered, there were significant differences for telomere length and methylation. Young individuals, regardless of their cytotypes, had the most methylated DNA. Regarding the ITRs, we found a signal on chromosome 1 in 2n = 50b. No evidence was found that telomere length or methylation could have influenced chromosomal rearrangements, although new cytotypes seem to have emerged within the distribution of parental cytotypes by the accumulation of different chromosomal rearrangements.
Asunto(s)
Roedores , Telómero , Humanos , Animales , Hibridación Fluorescente in Situ , Metilación , Cariotipo , Cariotipificación , Roedores/genética , Telómero/genéticaRESUMEN
Glioma is a term used to describe tumors derived from glial cells. These tumors are divided into subgroups based on the histological morphology and similarity of their differentiated glia cells. Traditionally, they are classified according to the World Health Organization and include astrocytomas, oligodendrogliomas, ependymomas, and oligoastrocytomas. Like most cancers, gliomas develop as a result of genetic changes that accumulate with tumor progression. Alterations in isocitrate dehydrogenase 1 (IDH1) and IDH2 were found to be relevant in the classification and prognostic of gliomas. Because of the importance of mutations in these genes, particularly in IDH1, in different proposals of the genesis and progression of gliomas, we analyzed the occurrence of mutations in these genes in samples obtained from patients from Belém (PA, Brazil) using polymerase chain reaction-single-strand conformation polymorphism followed by sequencing. We compared the results obtained from tumors of different malignancy grades, evaluating the significance of the associations between different variables. R132H was the only mutation found in 17.6% (6/34) of cases, including in astrocytomas, anaplastic astrocytomas, oligodendroglioma, and anaplastic oligoastrocytoma. No mutations were found in the IDH2 gene. We found no significant relationship between the identified mutations in IDH1 and the variables. Our data could not confirm that mutations in IDH1/IDH2 are indicative of malignancy and prognosis. However, the results support that the mutation in IDH1 gene was an early event in the development of gliomas, as it was found in tumors of different malignancy grades.
Asunto(s)
Glioma/genética , Isocitrato Deshidrogenasa/genética , Pronóstico , Adolescente , Adulto , Anciano , Brasil , Niño , Preescolar , Femenino , Glioma/patología , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Lactante , Masculino , Persona de Mediana Edad , Mutación , Clasificación del Tumor , Polimorfismo Conformacional Retorcido-SimpleRESUMEN
Breast cancer is the second most common origin of brain metastases, after lung cancer, and represents 14-20% of all cases. Abnormalities of chromosome 17 are important molecular genetic events in human breast cancer, and several oncogenes and tumor suppressor genes are located on this chromosome. In about half of all human cancers, the tumor suppressor gene TP53, located at 17p13.1, is either lost or mutated. Loss of p53 protein function influences not only cell cycle checkpoint controls and apoptosis, but also the regulation of other important stages of metastatic progression, such as cell migration and tissue invasion. The aim of our study was to identify numerical aberrations of chromosome 17 and TP53 in 5 subjects with brain metastasis from breast cancer using dual-color fluorescence in situ hybridization experiments. Deletion of TP53 was the most frequent alteration observed, suggesting that if this alteration is present in the primary tumors, breast tumors with loss of TP53 copies have a poorer prognosis and a higher chance for metastasis. If this is true, the analyses of chromosome 17 and TP53 in primary breast cancer could be important for predicting its metastatic potential.
Asunto(s)
Adenocarcinoma/patología , Neoplasias Encefálicas/genética , Neoplasias de la Mama/patología , Aberraciones Cromosómicas , Cromosomas Humanos Par 17/genética , Proteína p53 Supresora de Tumor/genética , Adulto , Neoplasias Encefálicas/secundario , Femenino , Eliminación de Gen , Humanos , Persona de Mediana EdadRESUMEN
During the last decades, New World monkey (NWM, Platyrrhini, Anthropoideae) comparative cytogenetics has shed light on many fundamental aspects of genome organisation and evolution in this fascinating, but also highly endangered group of neotropical primates. In this review, we first provide an overview about the evolutionary origin of the inferred ancestral NWM karyotype of 2n = 54 chromosomes and about the lineage-specific chromosome rearrangements resulting in the highly divergent karyotypes of extant NWM species, ranging from 2n = 16 in a titi monkey to 2n = 62 in a woolly monkey. Next, we discuss the available data on the chromosome phylogeny of NWM in the context of recent molecular phylogenetic analyses. In the last part, we highlight some recent research on the molecular mechanisms responsible for the large-scale evolutionary genomic changes in platyrrhine monkeys.
Asunto(s)
Cromosomas de los Mamíferos/genética , Evolución Molecular , Platirrinos/clasificación , Platirrinos/genética , Animales , Atelidae/clasificación , Atelidae/genética , Cebidae/clasificación , Cebidae/genética , Pintura Cromosómica , Análisis Citogenético , Cariotipo , Filogenia , Pitheciidae/clasificación , Pitheciidae/genética , Especificidad de la EspecieRESUMEN
This contribution describes and illustrates the male genitalia of two new species of Ectobiidae belonging to Pseudophyllodromiinae, Chorisoneura Brunner von Wattenwyl, and Blattellinae, Xestoblatta Hebard. Both species were collected in the Santa Lúcia Biological Reserve in the state of Espírito Santo, Brazil.
Asunto(s)
Cucarachas/anatomía & histología , Cucarachas/clasificación , Animales , Brasil , Ecosistema , Femenino , MasculinoRESUMEN
Callicebus is a complex genus of neotropical primates thought to include 29 or more species. Currently, the genus is divided into 5 species groups: donacophilus, cupreus, moloch, torquatus and personatus. However, the phylogenetic relationships among the species are still poorly understood. This genus is karyotypically diverse and shows extensive variation in diploid number (2n = 16 to 50). To foster a better understanding of the chromosomal diversities and phylogenetic relationships among the species of Callicebus, we performed a chromosome-painting analysis on the Callicebus personatus genome using human probes, and compared the resulting hybridization map to those of previously mapped titi species. We detected 38 hybridization signals per haploid autosomal set of C. personatus. Few ancestral syntenies were conserved without rearrangement, but 4 human associations (HSA20/13, 3c/8b, 1b/1c and 21/3a/15a/14) were demonstrated to be apomorphic traits for C. persona tus. G-banding suggested that these associations are shared with C. nigrifrons and C. coimbrai (personatus group), while C. personatus is linked with C. pallescens (donacophilus group) by 2 synapomorphies: HSA10b/11 (submetacentric) and an inversion of HSA1a.
Asunto(s)
Genoma , Pitheciidae/genética , Animales , Pintura Cromosómica , Cromosomas Humanos , Cromosomas de los Mamíferos , Femenino , Humanos , CariotipificaciónRESUMEN
The spectacled owl (Pulsatrix perspicillata), a species found in the Neotropical region, has 76 chromosomes, with a high number of biarmed chromosomes. In order to define homologies between Gallus gallus and Pulsatrixperspicillata (Strigiformes, Strigidae), we used chromosome painting with chicken DNA probes of chromosomes 1-10 and Z and telomeric sequences. This approach allowed a comparison between Pulsatrixperspicillata and other species of Strigidae already analyzed by chromosome painting (Strix nebulosa and Bubo bubo, both with 2n = 80). The results show that centric fusions and fissions have occurred in different chromosomal pairs and are responsible for the karyotypic variation observed in this group. No interstitial telomeric sequences were found. Although the largest pair of chromosomes in P. perspicillata and Bubo bubo are submetacentric, they are homologous to different chicken chromosomes: GGA1/GGA2 in P. perspicillata and GGA2/GGA4 in B. bubo.
Asunto(s)
Pollos/genética , Cromosomas/genética , Evolución Molecular , Estrigiformes/genética , Animales , Pintura Cromosómica , Hibridación Fluorescente in Situ , Cariotipificación , Telómero/genéticaRESUMEN
BACKGROUND: Chromosomal painting, using whole chromosome probes from humans and Saguinus oedipus, was used to establish karyotypic divergence among species of the genus Cebus, including C. olivaceus, C. albifrons, C. apella robustus and C. apella paraguayanus. Cytogenetic studies suggested that the species of this genus have conservative karyotypes, with diploid numbers ranging from 2n = 52 to 2n = 54. RESULTS: Banding studies revealed morphological divergence among some chromosomes, owing to variations in the size of heterochromatic blocks. This analysis demonstrated that Cebus species have five conserved human associations (i.e., 5/7, 2/16, 10/16, 14/15, 8/18 and 3/21) when compared with the putative ancestral Platyrrhini karyotype. CONCLUSION: The autapomorphies 8/15/8 in C. albifrons and 12/15 in C. olivaceus explain the changes in chromosome number from 54 to 52. The association 5/16/7, which has not previously been reported in Platyrrhini, was also found in C. olivaceus. These data corroborate previous FISH results, suggesting that the genus Cebus has a very similar karyotype to the putative ancestral Platyrrhini.
Asunto(s)
Cebus/genética , Bandeo Cromosómico/métodos , Pintura Cromosómica/métodos , Cromosomas de los Mamíferos , Filogenia , Animales , Cebus/clasificación , Humanos , Cariotipificación , Saguinus/genética , Especificidad de la EspecieRESUMEN
The Neotropical Phyllostomidae family is the third largest in the order Chiroptera, with 56 genera and 140 species. Most researchers accept this family as monophyletic but its species are anatomically diverse and complex, leading to disagreement on its systematics and evolutionary relationships. Most of the genera of Phyllostomidae have highly conserved karyotypes but with intense intergeneric variability, which makes any comparative analysis using classical banding difficult. The use of chromosome painting is a modern way of genomic comparison on the cytological level, and will clarify the intense intergenus chromosomal variability in Phyllostomidae. Whole chromosome probes of species were produced as a tool for evolutionary studies in this family from two species from different subfamilies, Phyllostomus hastatus and Carollia brevicauda, which have large morphological and chromosomal differences, and these probes were used in reciprocal chromosome painting. The hybridization of the Phyllostomus probes on the Carollia genome revealed 24 conserved segments, while the Carollia probes on the Phyllostomus genome detected 26 segments. Many chromosome rearrangements have occurred during the divergence of these two genera. The sequence of events suggested a large number of rearrangements during the differentiation of the genera followed by high chromosomal stability within each genus.
Asunto(s)
Quirópteros/genética , Pintura Cromosómica , Cromosomas de los Mamíferos/genética , Animales , Fibroblastos , Citometría de Flujo , Genoma , Cariotipificación , Metafase , América del SurRESUMEN
This paper presents the karyotype of Callicebus donacophilus pallescens for the first time. The analysis included G-, C-, NOR-banding techniques and FISH with chromosome painting probes from Saguinus oedipus and Homo sapiens. The results were compared with the karyotypes of Callicebus moloch donacophilus and C. moloch previously published. These three karyotypes display the same diploid number (2n = 50) but diverge about the number of biarmed and acrocentric chromosomes. The acrocentrics 14 and 15 from C. m. donacophilus and C. moloch have undergone an in-tandem fusion originating a large acrocentric (pair 10) in C. d. pallescens. The major submetacentric pair (pair 1) from C. d. donacophilus and C. moloch have undergone fission originating two acrocentric pairs in C. d. pallescens (pairs 15 and 22). Herein was evidence that, in spite of the high interspecific variation among Callicebus, most of the chromosomes remained conserved.