The Sperm Of Hexagenia (pseudeatonica) Albivitta Walker (ephemeroptera: Fossoriae: Ephemeridae)

This study describes the sperm morphology of the mayfly Hexagenia (Pseudeatonica) albivitta (Ephemeroptera). Its spermatozoon measures approximately 30 μm of which 9 μm corresponds to the head. The head is composed of an approximately round acrosomal vesicle and a cylindrical nucleus. The nucleus has two concavities, one in the anterior tip, where the acrosomal vesicle is inserted and a deeper one at its base, where the flagellum components are inserted. The flagellum is composed of an axoneme, a mitochondrion and a dense rod adjacent to the mitochondrion. A centriolar adjunct is also observed surrounding the axoneme in the initial portion of the flagellum and extends along the flagellum for at least 2 μm, surrounding the axoneme in a half-moon shape. The axoneme is the longest component of the flagellum, and it follows the 9+9+0 pattern, with no central pair of microtubules. At the posterior region of the flagellum, the mitochondrion has a dumb-bell shape in cross sections that, together with the rectangular mitochondrial-associated rod, is responsible for the flattened shape of the flagellum. An internal membrane is observed surrounding both mitochondrion and its associated structure.

Imunofenótipo e evolução de câncer de mama: comparação entre mulheres muito jovens e mulheres na pós-menopausa

OBJETIVO: avaliar características clínicas, patológicas e moleculares de carcinomas mamários em mulheres muito jovens em comparação a tumores de mulheres na pós-menopausa. MÉTODOS: foram selecionados 106 casos de câncer de mama de mulheres jovens e 130 casos de mulheres pós-menopausa. Foram analisados dados clínicos (idade ao diagnóstico, estadiamento, ocorrência de metástases, tempo de sobrevida global e livre de doença), anátomo-patológicos (tamanho do tumor, tipo e grau histológico do tumor primário) e marcadores moleculares (receptores de estrógeno e progesterona, HER2, p53, p63, citoqueratinas 5 e 14 e EGFR) com uso da imunoistoquímica empregando microarranjo de tecido. Foi analisada a relação entre as características clínico-patológicas, imunoistoquímicas e de sobrevidas global e livre de doença. RESULTADOS: as pacientes muito jovens apresentaram maior frequência de nuliparidade (p=0,03), maior diâmetro dos tumores (p<0,000), estadiamento clínico mais avançado (p=0,01), maior número de linfonodos positivos (p=0,001) e tumores pouco diferenciados (p=0,004). A maioria das pacientes jovens recebeu tratamento com quimioterapia (90,8%) e radioterapia (85,2%) e em menor proporção com tamoxifeno (31,5%), comparado às mulheres na pós-menopausa. Observamos baixa positividade para o receptor de estrógeno (49,1%; p=0,01) e alta positividade para a proteína HER2 (28,7%; p=0,03) nas mulheres jovens. O fenótipo triplo-negativo foi observado em 29,6% no grupo jovem e em 20% nas mulheres na pós-menopausa. Os tumores de fenótipo basal foram mais frequentes nas mulheres jovens (50%). As metástases sistêmicas ocorreram em 55,3% dos casos nas jovens e em 39,2% nas idosas. As sobrevidas global e livre de doença em cinco anos foram, respectivamente, 63 e 39% para as mulheres jovens e 75 e 67% para o grupo de mulheres na pós-menopausa. CONCLUSÕES: carcinomas mamários de mulheres muito jovens têm características clínicas, patológicas e moleculares mais agressivas quando comparadas às mulheres acima de 50 anos.

Time evolution of the South Atlantic Magnetic Anomaly

The South Atlantic Magnetic Anomaly (SAMA) is one of the most outstanding anomalies of the geomagnetic field. The SAMA secular variation was obtained and compared to the evolution of other anomalies using spherical harmonic field models for the 1590-2005 period. An analysis of data from four South American observatories shows how this large scale anomaly affected their measurements. Since SAMA is a low total field anomaly, the field was separated into its nondipolar, quadrupolar and octupolar parts. The time evolution of the non-dipole/total, quadrupolar/total and octupolar/total field ratios yielded increasingly high values for the South Atlantic since 1750. The SAMA evolution is compared to the evolution of other large scale surface geomagnetic features like the North and the South Pole and the Siberia High, and this comparison shows the intensity equilibrium between these anomalies in both hemispheres. The analysis of non-dipole fields in historical period suggests that SAMA is governed by (i) quadrupolar field for drift, and (ii) quadrupolar and octupolar fields for intensity and area of influence. Furthermore, our study reinforces the possibility that SAMA may be related to reverse fluxes in the outer core under the South Atlantic region.

Molecular systematics of Thorea (Rhodophyta, Thoreales) species in Brazil

This study aimed to evaluate species level taxonomy and phylogenetic relationship among Thorea species in Brazil and other regions of the world using two molecular markers - RUBISCO large subunit plastid gene (rbcL) and nuclear small-subunit ribosomal DNA (SSU rDNA). Three samples of Thorea from Brazil (states of Mato Grosso do Sul and São Paulo) and one sample from Dominican Republic (DR) were sequenced. Analyses based on partial sequences of rbcL (1,282 bp) and complete sequences of SSU (1,752 bp) were essentially congruent and revealed that Thoreales formed a distinct monophyletic clade, which had two major branches with high support, representing the genera Thorea and Nemalionopsis. Thorea clade had four main branches with high support for all analyses, each one representing the species: 1) T. gaudichaudii C. Agardh from Asia (Japan and Philippines) - this clade occurred only in the rbcL analyses; 2) T. violacea Bory from Asia (Japan) and North America (U.S.A. and DR); 3) T. hispida (Thore) Desvaux from Europe (England) and Asia (Japan); 4) a distinct group with the three Brazilian samples (sequence identity: rbcL 97.2%, 1,246 bp; SSU 96.0-98.1%, 1,699-1,720 bp). The Brazilian samples clearly formed a monophyletic clade based on both molecular markers and was interpreted as a separate species, for which we resurrected the name T. bachmannii Pujals. Morphological and molecular evidences indicate that the Thoreales is well-resolved at ordinal and generic levels. In contrast, Thorea species recognized by molecular data require additional characters (e.g. reproductive and chromosome numbers) to allow consistent and reliable taxonomic circumscription aiming at a world revision based on molecular and morphological evidences.

Thaptomys Thomas 1915 (Rodentia, Sigmodontinae, Akodontini) with karyotypes 2n = 50, FN = 48, and 2n = 52, FN = 52: two monophyletic lineages recovered by molecular phylogeny

A novel karyotype with 2n = 50, FN = 48, was described for specimens of Thaptomys collected at Una, State of Bahia, Brazil, which are morphologically indistinguishable from Thaptomys nigrita, 2n = 52, FN = 52, found in other localities. It was hence proposed that the 2n = 50 karyotype could belong to a distinct species, cryptic of Thaptomys nigrita, once chromosomal rearrangements observed, along with the geographic distance, might represent a reproductive barrier between both forms. Phylogenetic analyses using maximum parsimony and maximum likelihood based on partial cytochrome b sequences with 1077 bp were performed, attempting to establish the relationships among the individuals with distinct karyotypes along the geographic distribution of the genus; the sample comprised 18 karyotyped specimens of Thaptomys, encompassing 15 haplotypes, from eight different localities of the Atlantic Rainforest. The intra-generic relationships corroborated the distinct diploid numbers, once both phylogenetic reconstructions recovered two monophyletic lineages, a northeastern clade grouping the 2n = 50 and a southeastern clade with three subclades, grouping the 2n = 52 karyotype. The sequence divergence observed between their individuals ranged from 1.9% to 3.5%.

Synteny of human chromosomes 14 and 15 in the platyrrhines (Primates, Platyrrhini)

In order to study the intra- and interspecific variability of the 14/15 association in Platyrrhini, we analyzed 15 species from 13 genera, including species that had not been described yet. The DNA libraries of human chromosomes 14 and 15 were hybridized to metaphases of Alouatta guariba clamitans, A. caraya, A. sara, Ateles paniscus chamek, Lagothrix lagothricha, Brachyteles arachnoides, Saguinus midas midas, Leontopithecus chrysomelas, Callimico goeldii, Callithrix sp., Cebus apella, Aotus nigriceps, Cacajao melanocephalus, Chiropotes satanas and Callicebus caligatus. The 14/15 hybridization pattern was present in 13 species, but not in Alouatta sara that showed a 14/15/14 pattern and Aotus nigriceps that showed a 15/14/15/14 pattern. In the majority of the species, the HSA 14 homologue retained synteny for the entire chromosome, whereas the HSA 15 homologue displayed fragmented segments. Within primates, the New World monkeys represent the taxon with the highest variability in chromosome number (2n = 16 to 62). The presence of the HSA 14/15 association in all species and subspecies studied herein confirms that this association is the ancestral condition for platyrrhines and that this association has been retained in most platyrrhines, despite the occurrence of extensive inter- and intrachromosomal rearrangements in this infraorder of Primates.

Astyanax hastatus Myers, 1928 (Teleostei, Characidae): a new species complex within the genus Astyanax?

Four populations of Astyanax hastatus Myers 1928 from the Guapimirim River basin (Rio de Janeiro State) were analyzed and three distinct cytotypes identified. These cytotypes presented 2n = 50 chromosomes, with 4M+8SM+10ST+28A (Cytotype A), 8M+10SM+14ST+18A (Cytotype B), 6M+8SM+4ST+32A (Cytotype C) and scanty heterochromatin, mainly located throughout pericentromeric regions of several chromosomal pairs. No homologies with the As-51 satellite DNA were observed in the three cytotypes, although all of them presented multiple 18S rDNA sites, as detected by both silver nitrate staining and FISH (fluorescent in situ hybridization). The application of the term "species complex" in Astyanax is discussed from a cytotaxonomic viewpoint.

Use of chromosome microdissection in fish molecular cytogenetics

Chromosome microdissection is a technique in which whole chromosomes or chromosomal segments are dissected under an inverted microscope yielding chromosome-specific sequences. Several protocol modifications introduced during the past 15 years reduced the number of chromosomes required for most applications. This is of particular interest to fish molecular cytogenetics, since most species present highly uniform karyotypes which make impossible the collection of multiple copies of the same chromosome. Probes developed in this manner can be used to investigate chromosome homologies in closely related species. Here we describe a protocol recently used in the gymnotiform species group Eigenmannia and review the major steps involved in the generation of these markers focusing on protocol modifications aiming to reduce the number of required chromosomes.

Localization of ribosomal genes in three Pimelodus species (Siluriformes, Pimelodidae) of the São Francisco River: 5S genes as species markers and conservation of the 18S rDNA sites

Pimelodidae is one of the most representative of Neotropical catfish families. However, these fish are still poorly studied in terms of cytogenetics, especially regarding the application of more accurate techniques such as the chromosomal localization of ribosomal genes. In the present work, fluorescent in situ hybridization with 5S and 18S rDNA probes was employed for rDNA site mapping in Pimelodus sp., P. fur and P. maculatus from the São Francisco River in the Três Marias municipality - MG. The results from the application of the 18S probe confirmed the previous data obtained by silver nitrate staining, identifying a simple nucleolar organizing region system for these species. However, the labeling results from the 5S rDNA probe demonstrated a difference in the number and localization of these sites between the analyzed species. The obtained data allowed inferences on the possible processes involved in the karyotypic evolution of this genus.

Biologia molecular como ferramenta no esporte de alto rendimento: possibilidades e perspectivas

Várias estratégias têm sido pensadas com o propósito de se utilizar a biologia molecular como ferramenta na pré-seleção e na seleção de talentos esportivos, na manipulação genética visando ao aumento ou à diminuição da produção de determinadas substâncias pelo organismo, na prescrição do treinamento e na recuperação de lesões. Portanto, o objetivo desta revisão é apresentar o DNA como regulador do funcionamento do organismo e de que forma alterações no perfil genético, tanto espontâneas como induzidas artificialmente, podem modular respostas fisiológicas e morfológicas por alterar a expressão de determinadas proteínas. Será dada especial atenção à descrição dos procedimentos utilizados para a manipulação genética, nos baixos riscos associados e nas estratégias que têm sido desenvolvidas com o objetivo de detectá-la. Com base em conhecimentos científicos, coerência e bom senso, diversas visões devem ser expostas e amplamente discutidas para ser definido o que é permitido e o que é proibido nas competições esportivas.

Molecular markers and genetic diversity of Plasmodium vivax

Enhanced understanding of the transmission dynamics and population genetics for Plasmodium vivax is crucial in predicting the emergence and spread of novel parasite phenotypes with major public health implications, such as new relapsing patterns, drug resistance and increased virulence. Suitable molecular markers are required for these population genetic studies. Here, we focus on two groups of molecular markers that are commonly used to analyse natural populations of P. vivax. We use markers under selective pressure, for instance, antigen-coding polymorphic genes, and markers that are not under strong natural selection, such as most minisatellite and microsatellite loci. First, we review data obtained using genes encoding for P. vivax antigens: circumsporozoite protein, merozoite surface proteins 1 and 3α, apical membrane antigen 1 and Duffy binding antigen. We next address neutral or nearly neutral molecular markers, especially microsatellite loci, providing a complete list of markers that have already been used in P. vivax populations studies. We also analyse the microsatellite loci identified in the P. vivax genome project. Finally, we discuss some practical uses for P. vivax genotyping, for example, detecting multiple-clone infections and tracking the geographic origin of isolates.

A phylogenetic analysis of Brycon and Henochilus (Characiformes, Characidae, Bryconinae) based on the mitochondrial gene 16S rRNA

The genus Brycon, the largest subunit of the Bryconinae, has 42 valid species distributed from southern Mexico to the La Plata River in Argentina. Henochilus is a monotypic genus, comprising a single species (H. wheatlandii) found in the upper Rio Doce basin. In the present study, partial sequences of the mitochondrial gene 16S were obtained for fifteen species of Brycon and for Henochilus wheatlandii. The results showed that the genus Brycon is paraphyletic, since Henochilus is the sister-group of B. ferox and B. insignis. The most basal species analyzed were the trans-Andean species B. henni, B. petrosus, and B. chagrensis.

Enzyme kinetics, structural analysis and molecular modeling studies on a series of Schistosoma mansoni PNP inhibitors

The enzyme purine nucleoside phosphorylase from Schistosoma mansoni (SmPNP) is an attractive molecular target for the development of novel drugs against schistosomiasis, a neglected tropical disease that affects about 200 million people worldwide. In the present work, enzyme kinetic studies were carried out in order to determine the potency and mechanism of inhibition of a series of SmPNP inhibitors. In addition to the biochemical investigations, crystallographic and molecular modeling studies revealed important molecular features for binding affinity towards the target enzyme, leading to the development of structure-activity relationships (SAR).