Biological and DNA evidence of two dissimilar populations of the Rhipicephalus sanguineus tick group (Acari : Ixodidae) in South America

In this work, the biology, mitochondrial DNA and fertility of hybrids from two strains of Rhipicephalus sanguineus, from Brazil and Argentina, were compared. Engorged larvae, nymphs and adults from Argentina weighed more and the engorgement period of adult females was significantly longer than those of their Brazilian counterparts, whereas adult female tick yield rate was higher for the Brazilian strain. High intraspecific divergence of mitochondrial DNA was detected between R. sanguineus from Brazil and Argentina. on the other hand, a strong genetic relationship was detected between European and Argentinean R. sanguineus populations while the Brazilian population appeared to be related to the African Rhipicephalus turanicus. Adult hybrid females laid eggs, which were mostly unviable, whereas a mean of more than 1400 larvae hatched per egg mass from pure Brazilian and Argentinean strains. These results showed that differences between these strains are greater than previously assumed and that the biosysternatic status of R. sanguineus ticks from South America should be re-evaluated. Wide variations, such as these might account for the reported worldwide differences in biology and vector capacity of this species. (c) 2005 Elsevier B.V. All rights reserved.

Molecular phylogeny of Moenkhausia (Characidae) inferred from mitochondrial and nuclear DNA evidence

Moenkhausia is one of the most speciose genera in Characidae, currently composed of 75 nominal species of small fishes distributed across South American hydrographic basins, primarily the Amazon and Guyanas. Despite the large number of described species, studies involving a substantial number of its species designed to better understand their relationships and putative monophyly are still lacking. In this study, we analysed a large number of species of Moenkhausia to test the monophyly of the genus based on the phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes. The in-group included 29 species of Moenkhausia, and the out-group was composed of representatives of Characidae and other members of Characiformes. All species of Moenkhausia belong to the same clade (Clade C); however, they appear distributed in five monophyletic groups along with other different genera, which means that Moenkhausia is polyphyletic and indicates the necessity of an extensive revision of the group. © 2013 Blackwell Verlag GmbH.

Chromosomal mapping of repetitive DNAs in the beetle Dichotomius geminatus provides the first evidence for an association of 5S rRNA and histone H3 genes in insects, and repetitive DNA similarity between the B chromosome and A complement

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

Electrochemical and theoretical evaluation of the interaction between dna and amodiaquine: evidence of the guanine adduct formation

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

Evidence of Leishmania spp. antibodies and DNA in bush dogs (Speothos venaticus) in Brazil

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

NO EVIDENCE of PATHOLOGICAL AUTOIMMUNITY FOLLOWING MYCOBACTERIUM LEPRAE HEAT-SHOCK PROTEIN 65-DNA VACCINATION IN MICE

Heat-shock proteins (HSPs) are currently one of the most promising targets for the development of immunotherapy against tumours and autoimmune disorders. This protein family has the capacity to activate or modulate the function of different immune system cells. They induce the activation of monocytes, macrophages and dendritic cells, and contribute to cross-priming, an important mechanism of presentation of exogenous antigen in the context of MHC class I molecules, These various immunological properties of HSP have encouraged their use in several clinical trials. Nevertheless, an important issue regarding these proteins is whether the high homology among HSPs across different species may trigger the breakdown of immune tolerance and induce autoimmune diseases. We have developed a DNA vaccine codifying the Mycobacterium leprae Hsp65 (DNAhsp65), which showed to be highly immunogenic and protective against experimental tuberculosis. Here, we address the question of whether DNAhsp65 immunization could induce pathological autoimmunity in mice. Our results show that DNAhsp65 vaccination induced antibodies that can recognize the human Hsp60 but did not induce harmful effects in 16 different organs analysed by histopathology up to 210 days after vaccination. We also showed that anti-DNA antibodies were not elicited after DNA vaccination. The results are important for the development of both HSP and DNA-based immunomodulatory agents.

Molecular evidence of ribosomal DNA (rDNA) amplification of a minichromosome derived from Drosophila arizonae in D. mulleri-D. arizonae hybrid males

We present data supporting cytogenetic observations on nucleolar dominance in hybrids between Drosophila arizonae and D. mulleri. Our approach was to compare the rDNA restriction patterns between the parental species and their hybrids. Results demonstrated that the minichromosome attached to the nucleolus in hybrid males is derived from D. arizonae.

Structural and functional evidence that a B chromosome in the characid fish Astyanax scabripinnis is an isochromosome

Astyanax scabripinnis possesses a widespread polymorphism for metacentric B chromosomes as large as the largest chromosome pair in the A complement. on the basis of C-banding pattern, it was hypothesized that these B chromosomes are isochromosomes that have arisen by means of centromere misdivision and chromatid nondisjunction. In the present paper we test this hypothesis by analysing (i) the localization of a repetitive DNA sequence on both B chromosome arms, and (ii) synaptonemal complex formation, in order to test the functional homology of both arms. Genomic DNA digested with KpnI and analysed by gel electrophoresis showed fragments in a ladder-like pattern typical of tandemly repetitive DNA. These fragments were cloned and their tandem organization in the genome was confirmed. A 51-bp long consensus sequence, which was AT-rich (59%) and contained a variable region and two imperfect reverse sequences, was obtained. Fluorescence in situ hybridization (FISH) localized this repetitive DNA into noncentromeric constitutive heterochromatin which encompasses the terminal region of some acrocentric chromosomes, the NOR region, and interstitial polymorphic heterochromatin in chromosome 24. Most remarkably, tandem repeats were almost symmetrically placed in the two arms of the B chromosome, with the exception of two additional small clusters proximally located on the slightly longer arm. Synaptonemal complex (SC) analysis showed 26 completely paired SCs in males with 1B. The ring configuration of the B univalent persisting until metaphase I suggests that the two arms formed chiasmata. All these data provided strong support for the hypothesis that the B chromosome is an isochromosome.

Heteroplasmy in Hair: Study of Mitochondrial DNA Third Hypervariable Region in Hair and Blood Samples

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

Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies

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

DNA viruses in human cancer: An integrated overview on fundamental mechanisms of viral carcinogenesis

The first experimental data suggesting that neoplasm development in animals might be influenced by infectious agents were published in the early 1900s. However, conclusive evidence that DNA viruses play a role in the pathogenesis of some human cancers only emerged in the 1950s, when Epstein-Barr virus (EBV) was discovered within Burkitt lymphoma cells. Besides EBV, other DNA viruses consistently associated with human cancers are the hepatitis B virus (HBV), human papillomavirus (HPV), and Kaposi sarcoma herpesvirus (KSHV). Although each virus has unique features, it is becoming clearer that all these oncogenic agents target multiple cellular pathways to support malignant transformation and tumor development. (c) 2006 Elsevier B.V.. All rights reserved.

DNA damage in multiple organs after exposure to chlorhexidine in Wistar rats

Since chlorhexidine is effective against microorganisms, it is widely recommended in dentistry. However, studies have provided evidence that chlorhexidine is toxic for a variety of cell types. In order to identify potential genotoxins in different cell types, the purpose of this study was to investigate whether chlorhexidine digluconate is able to cause, in terms of DNA damage, alterations in leukocytes, liver, kidney and urinary bladder by the single cell gel (comet) assay. Ten male Wistar rats were divided into two groups: a negative control and the experimental group treated with 3 ml of 0.12% chlorhexidine digluconate by gavage once a day for 8 days. Statistically significant increases of DNA damage was observed in leukocytes and kidney cells of the chlorhexidine digluconate treated group as depicted by the mean tail moment. Taken together, the data indicate that leukocytes and kidney cells are potential targets for primary DNA damage following oral exposure to chlorhexidine digluconate as detected by single cell gel (comet) assay. (c) 2006 Elsevier GmbH. All rights reserved.

Evidence of epigenetic regulation of the tumor suppressor gene cluster flanking RASSF1 in breast cancer cell lines

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

Species delimitation in sharpnose sharks (genus Rhizoprionodon) in the western Atlantic Ocean using mitochondrial DNA

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

Populations analysis of the Brazilian Sharpnose Shark Rhizoprionodon lalandii (Chondrichthyes: Carcharhinidae) on the São Paulo coast, Southern Brazil: inferences from mt DNA sequences

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