The ultrastructure of malpighian tubules and the chemical composition of the cocoon of Aeolothrips intermedius Bagnall (Thysanoptera)

The secretory activity of the two branched malpighian tubules (MTs) of the second‐instar larva in Aeolothrips intermedius is described. MTs of adult thrips have the typical ultrastructure of excretory epithelium with apical microvilli containing long mitochondria and a rich system of basal membrane infoldings. In the second‐instar larva just before pupation, the ultrastructure of MT epithelial cells is dramatically different, and there are numerous huge Golgi systems in the cytoplasm. These cells are involved in an intense secretory activity to produce an electron‐dense product which is released into the MTs lumen. This secretion is extruded from the hindgut and used by the second‐instar larva to build an elaborate protective cocoon for pupation. Electron‐spray‐ionization mass spectrometry analysis of the cocoon revealed the presence of a β‐N‐acetyl‐glucosamine, the main component of chitin, which is also present in the cocoons of Neuroptera and some Coleoptera. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Adenine release is fast in MutY-catalyzed hydrolysis of G:A and 8-Oxo-G:A DNA mismatches

MutY, a DNA repair enzyme, is unusual in that it binds exceedingly tightly to its products after the chemical steps of catalysis. Until now it was not known whether the product being released in the rate-limiting step was DNA, adenine, or both. MutY hydrolyzes adenine from 8-oxo-G:A (OG:A) base pair mismatches as the first step in the base excision repair pathway, as well as from G:A mismatches. The products are adenine and DNA containing an apurinic (AP) site. Tight product binding may have a physiological role in preventing further damage at the OG:AP site. We developed a rate assay using [8-14C]adenine in OG:A or G:A mismatches that distinguishes between adenine hydrolysis and adenine release. [8-14C]Adenine was released quickly from the MutY.AP-DNA.[8-14C]adenine complex, with a rate constant greater than 5 min-1. This was much faster than the rate-limiting step, at 0.006-0.015 min-1. Gel retardation experiments showed that AP-DNA release was very slow, consistent with it being the rate-limiting step. Thus, the kinetic mechanism involves fast adenine release after hydrolysis followed by rate-limiting AP-DNA release. Adenine appears to be buried deep in the protein.DNA interface, but there is enough flexibility or open space for it to dissociate from the MutY.APDNA.adenine complex. These results have implications for the catalytic mechanism of MutY.     

Importance of the lid and cap domains for the catalytic activity of gastric lipases

Human gastric lipase (HGL) is an enzyme secreted by the stomach, which is stable and active despite the highly acidic environment. It has been clearly established that this enzyme is responsible for 30% of the fat digestion processes occurring in human. This globular protein belongs to the alpha/beta hydrolase fold family and its catalytic serine is deeply buried under a domain called the extrusion domain, which is composed of a 'cap' domain and a segment consisting of 58 residues, which can be defined as a lid. The exact roles played by the cap and the lid domains during the catalytic step have not yet been elucidated. We have recently solved the crystal structure of the open form of the dog gastric lipase in complex with a covalent inhibitor. The detergent molecule and the inhibitor were mimicking a triglyceride substrate that would interact with residues belonging to both the cap and the lid domains. In this study, we have investigated the role of the cap and the lid domains, using site-directed mutagenesis procedures. We have produced truncated mutants lacking the lid and the cap. After expressing these mutants and purifying them, their activity was found to have decreased drastically in comparison with the wild type HGL. The lid and the cap domains play an important role in the catalytic reaction mechanism. Based on these results and the structural data (open form of DGL), we have pointed out the cap and the lid residues involved in the binding with the lipidic substrate.     

High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups

We recently proposed that patterns of evolution of non-LTR retrotransposable elements can be used to study patterns of spontaneous mutation. Transposition of non-LTR retrotransposable elements commonly results in creation of 5' truncated, "dead-on-arrival" copies. These inactive copies are effectively pseudogenes and, according to the neutral theory, their molecular evolution ought to reflect rates and patterns of spontaneous mutation. Maximum parsimony can be used to separate the evolution of active lineages of a non-LTR element from the fate of the "dead-on-arrival" insertions and to directly assess the relative frequencies of different types of spontaneous mutations. We applied this approach using a non-LTR element, Helena, in the Drosophila virilis group and have demonstrated a surprisingly high incidence of large deletions and the virtual absence of insertions. Based on these results, we suggested that Drosophila in general may exhibit a high rate of spontaneous large deletions and have hypothesized that such a high rate of DNA loss may help to explain the puzzling dearth of bona fide pseudogenes in Drosophila. We also speculated that variation in the rate of spontaneous deletion may contribute to the divergence of genome size in different taxa by affecting the amount of superfluous "junk" DNA such as, for example, pseudogenes or long introns. In this paper, we extend our analysis to the D. melanogaster subgroup, which last shared a common ancestor with the D. virilis group approximately 40 MYA. In a different region of the same transposable element, Helena, we demonstrate that inactive copies accumulate deletions in species of the D. melanogaster subgroup at a rate very similar to that of the D. virilis group. These results strongly suggest that the high rate of DNA loss is a general feature of Drosophila and not a peculiar property of a particular stretch of DNA in a particular species group.      

"Healthy Men" and High Mortality: Contributions from a Population-Based Study for the Gender Paradox Discussion

Background

Inequalities between men and women in morbidity and mortality show a contrast, which has been called gender paradox. Most studies evaluating this paradox were conducted in high-income countries and, until now, few investigations have been performed in Brazil. This study aims to estimate the magnitude of inequalities between adult men and women in several dimensions: demographic and socioeconomic, health behaviors, morbidity, use of health services and mortality.

Methods

The data were obtained from population-based household survey carried out in Campinas (Campinas Health Survey 2008/09) corresponding to 957 people, and data from the Mortality Information System (MIS) between 2009 and 2011. Prevalences and prevalence ratios were analyzed in order to verify the differences between men and women regarding socioeconomic and demographic variables, health behaviors, morbidities and consultations in the last two weeks. Mortality rates and the ratio between coefficients considering the underlying causes of death were calculated.

Results

Women had a greater disadvantage in socioeconomic indicators, chronic diseases diagnosed by a health professional and referred health problems as well as make more use of health services, while men presented higher frequency of most unhealthy behaviors and excessive mortality for all causes investigated.

Conclusions

The findings contribute to the discussion of gender paradox and demonstrate the need to employ health actions that consider the differences between men and women in the various health dimensions analyzed. The premature male mortality from preventable causes was outstanding, making clear the need for more effective prevention and health promotion directed to this segment of the population.     

Morphology and development of additional bony elements in the genus Brachycephalus (Anura: Brachycephalidae)

We describe the extra bony elements, plates, and osteoderms present in species of the genus Brachycephalus. Samples of eight species of Brachycephalus, including seven populations of Brachycephalus ephippium, were examined. The large additional elements associated with the skull (parotic plate) and vertebrae (vertebral and paravertebral plates) all comprise intramembranous bone, similar to that of the frontoparietal or nasal bones of the skull of most of frogs. Additionally, in the dermis of one unnamed species, we discovered and described true osteoderms. We discuss the morphological nature and diversity of theses elements and their importance as evidence of phylogenetic relationship within Brachycephalus. In summary, three distinct conditions of extra bony elements occur in the genus Brachycephalus: (1) bony plates may be present or absent in species of the genus; (2) a few, small bony plates may be developed and these may be represented by (a) paravertebral plates small and restricted to the distal ends of the transverse processes of the presacral IV, (b) parotic plates small and not covering the tops of the squamosals, and (c) ornamented spinal plates on all vertebrae; and (3) well‐developed bony plates may be present as (a) paravertebral plates forming a ‘bone‐shield’ on the dorsal surface of the trunk, ornamented, and visible through the integument, (b) parotic plates covering the tops of the squamosals, and (c) spinal plates associated with all vertebrae, and ornamented on vertebrate I–VI. Although the phenomenon of miniaturization may be associated with the appearance of new elements in at least some of the species in the genus, the traditional rule may not be universally applicable. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 752–767.