A New Species of Thraulodes (Ephemeroptera: Leptophlebiidae) from Mexico

A new species of Thraulodes from Mexico is described from male and female imagines. The male imagines of this species have very characteristic genitalia that allow its easy separation from the other known species of the genus.     

Soil Carbon Turnover Measurement by Physical Fractionation at a Forest-to-Pasture Chronosequence in the Brazilian Amazon

The effect of conversion from forest-to-pasture upon soil carbon stocks has been intensively discussed, but few studies focus on how this land-use change affects carbon (C) distribution across soil fractions in the Amazon basin. We investigated this in the 20 cm depth along a chronosequence of sites from native forest to three successively older pastures. We performed a physicochemical fractionation of bulk soil samples to better understand the mechanisms by which soil C is stabilized and evaluate the contribution of each C fraction to total soil C. Additionally, we used a two-pool model to estimate the mean residence time (MRT) for the slow and active pool C in each fraction. Soil C increased with conversion from forest-to-pasture in the particulate organic matter (>250 μm), microaggregate (53–250 μm), and d-clay (<2 μm) fractions. The microaggregate comprised the highest soil C content after the conversion from forest-to-pasture. The C content of the d-silt fraction decreased with time since conversion to pasture. Forest-derived C remained in all fractions with the highest concentration in the finest fractions, with the largest proportion of forest-derived soil C associated with clay minerals. Results from this work indicate that microaggregate formation is sensitive to changes in management and might serve as an indicator for management-induced soil carbon changes, and the soil C changes in the fractions are dependent on soil texture.     

Specific and Selective Bacteriophages in the Fight against Multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients. Several A. baumannii strains are multidrug resistant and infect wounds, bones, and the respiratory tract. Current studies are focused on finding new effective agents against A. baumannii. Phage therapy is a promising means to fight this bacterium and many studies on procuring and applying new phages against A. baumannii are currently being conducted. As shown in animal models, phages against multidrug-resistant A. baumannii may control bacterial infections caused by this pathogen and may be a real hope to solve this dangerous health problem.     

Secretases as therapeutic targets for Alzheimer's disease

Accumulation of amyloid-β (Aβ) is widely accepted as the key instigator of Alzheimer’s disease (AD). The proposed mechanism is that accumulation of Aβ results in inflammatory responses, oxidative damages, neurofibrillary tangles and, subsequently, neuronal/synaptic dysfunction and neuronal loss. Given the critical role of Aβ in the disease process, the proteases that produce this peptide are obvious targets. The goal would be to develop drugs that can inhibit the activity of these targets. Protease inhibitors have proved very effective for treating other disorders such as AIDS and hypertension. Mutations in APP (amyloid-β precursor protein), which flanks the Aβ sequence, cause early-onset familial AD, and evidence has pointed to the APP-to-Aβ conversion as a possible therapeutic target. Therapies aimed at modifying Aβ-related processes aim higher up the cascade and are therefore more likely to be able to alter the progression of the disease. However, it is not yet fully known whether the increases in Aβ levels are merely a result of earlier events that were already causing the disease.     

Quantitative determination of gene strand bias in prokaryotic genomes

Comparative genometrics of microorganisms is a relatively new area, in which genome properties are translated into numerical indexes. Such indexes can be used for a comprehensive and comparative analysis of microbial genomes, contributing to the understanding of their evolution. This work presents a new method for quantitative determination of gene strand bias in prokaryotic chromosomes, in which data transformation of gene position skew leads to a numerical index that can be applied to quantitative comparisons of genome organization. It was applied in the comparative analysis of 49 completely sequenced Firmicutes genomes, allowing the distinction of groups defined according to their patterns of gene strand preference. The resulting groups revealed that, regarding gene strand bias, reduced genomes are, in general, the more disordered among Firmicutes, while genomes of extremophile organisms comprehend those with the highest degree of genome organization in this phylum.     

The plant glycosyltransferase clone collection for functional genomics

The glycosyltransferases (GTs) are an important and functionally diverse family of enzymes involved in glycan and glycoside biosynthesis. Plants have evolved large families of GTs which undertake the array of glycosylation reactions that occur during plant development and growth. Based on the Carbohydrate‐Active enZymes (CAZy) database, the genome of the reference plant Arabidopsis thaliana codes for over 450 GTs, while the rice genome (Oryza sativa) contains over 600 members. Collectively, GTs from these reference plants can be classified into over 40 distinct GT families. Although these enzymes are involved in many important plant specific processes such as cell‐wall and secondary metabolite biosynthesis, few have been functionally characterized. We have sought to develop a plant GTs clone resource that will enable functional genomic approaches to be undertaken by the plant research community. In total, 403 (88%) of CAZy defined Arabidopsis GTs have been cloned, while 96 (15%) of the GTs coded by rice have been cloned. The collection resulted in the update of a number of Arabidopsis GT gene models. The clones represent full‐length coding sequences without termination codons and are Gateway^® compatible. To demonstrate the utility of this JBEI GT Collection, a set of efficient particle bombardment plasmids (pBullet) was also constructed with markers for the endomembrane. The utility of the pBullet collection was demonstrated by localizing all members of the Arabidopsis GT14 family to the Golgi apparatus or the endoplasmic reticulum (ER). Updates to these resources are available at the JBEI GT Collection website http://www.addgene.org/ .     

β-Amyloid carrying the Dutch mutation has diverse effects on calpain-mediated toxicity in hippocampal neurons

Hereditary cerebral hemorrhage with amyloidosis-Dutch type is a disorder associated with a missense mutation (E693Q) in the β-amyloid (Aβ)-coding region of the amyloid precursor protein (APP). This familial disease is characterized by cognitive deficits secondary to intracerebral hemorrhage and, in some cases, progressive Alzheimer's disease (AD)-like dementia. Although this mutation was the first ever reported in the human APP gene, little is known about the molecular mechanisms underlying the direct toxic effects of this mutated Aβ on central neurons. In the present study, we assessed the role of calpain-mediated toxicity in such effects using an AD primary culture model system. Our results showed that Dutch mutant Aβ (E22Q) induced calpain-mediated cleavage of dynamin 1 and a significant decrease in synaptic contacts in mature hippocampal cultures. These synaptic deficits were similar to those induced by wild-type (WT) Aβ. In contrast, calpain-mediated tau cleavage leading to the generation of a 17-kDa neurotoxic fragment, as well as neuronal death, were significantly reduced in E22Q Aβ-treated neurons when compared with WT Aβ-treated ones. This complex regulation of the calpain-mediated toxicity pathway by E22Q Aβ could have some bearing in the pathobiology of this familial AD form.     

A new genus of Syllidae (Polychaeta) from Western Australia

During a study carried out on the subfamily Exogoninae (Syllidae) from Australia, several specimens of a new genus and species were found in samples of dead coral substrate from Western Australia. They have long palps, fused except for a terminal notch, long median and two short lateral antennae, a single pair of short tentacular cirri, and short dorsal cirri, somewhat longer than the parapodial lobes. These characters resemble those of the genus Exogone Örsted, 1845. However, all these appendages are articulated. The chaetae are very similar to those of several species of Syllis Lamarck, 1818, having coarse spines on the margin of compound chaetal blades and truncated dorsal simple chaetae. Furthermore, the pharynx begins in chaetiger 3, posterior to the peristomium, as in many species of the genus Syllis; this condition does not occur in any described species of Exogone. The new genus is provisionally proposed to belong to the subfamily Syllinae, although it has some characters typical of the Exogoninae. Examination under the SEM shows another peculiar feature, the nuchal organs are distinctly laterally located. Within the Syllinae, only Paratyposyllis Hartmann-Schröder, 1962 has a single pair of tentacular cirri, but in that genus, the palps are only basally fused.