The Yku70-Yku80 complex contributes to regulate double-strand break processing and checkpoint activation during the cell cycle

DNA double-strand breaks (DSBs) are repaired by non-homologous end joining (NHEJ) or homologous recombination (HR). HR requires 5' DSB end degradation that occurs in the presence of cyclin-dependent kinase (CDK) activity. Here, we show that a lack of any of the NHEJ proteins Yku (Yku70-Yku80), Lif1 or DNA ligase IV (Dnl4) increases 5' DSB end degradation in G1 phase, with ykuDelta cells showing the strongest effect. This increase depends on MRX, the recruitment of which at DSBs is enhanced in ykuDelta G1 cells. DSB processing in G2 is not influenced by the absence of Yku, but it is delayed by Yku overproduction, which also decreases MRX loading on DSBs. Moreover, DSB resection in ykuDelta cells occurs independently of CDK activity, suggesting that it might be promoted by CDK-dependent inhibition of Yku.     

Pressure induced stability: from pneumatic structures to Tensairity~

1 Introductionready for the breakthrough of manned air travel. ItThe fascination of pneumatic structures beginstook more than a hundred years to establish reliablewith the fascination of the sky. The first techno-passenger transport through air with gas-filled air-logically relevant realisations of inflatable devicesships. Dirigibles had a boom at the beginning of thedate back to 1783, when the Mongolfier brothers with20th century, but the technology could soon notheir hot air balloon were th…     

An overview of pancreatic beta-cell defects in human type 2 diabetes: implications for treatment

Type 2 diabetes is the most common form of diabetes in humans. It results from a combination of factors that impair beta-cell function and tissue insulin sensitivity. However, growing evidence is showing that the beta-cell is central to the development and progression of this form of diabetes. Reduced islet and/or insulin-containing cell mass or volume in Type 2 diabetes has been reported by several authors. Furthermore, studies with isolated Type 2 diabetic islets have consistently shown both quantitative and qualitative defects of glucose-stimulated insulin secretion. The impact of genotype in affecting beta-cell function and survival is a very fast growing field or research, and several gene polymorphisms have been associated with this form of diabetes. Among acquired factors, glucotoxicity, lipotoxicity and altered IAPP processing are likely to play an important role. Interestingly, however, pharmacological intervention can improve several defects of Type 2 diabetes islet cells in vitro, suggesting that progression of the disease might not be relentless.     

The role of Li+, Na+, and K+ in the ligand binding inside the human acetylcholinesterase gorge

Alkali cations can affect the catalytic efficiency of enzymes. This is particularly true when dealing with enzymes whose substrate bears a formal positive charge. Computational and biochemical approaches have been combined to shed light on the atomic aspects of the role of Li(+), Na(+), and K(+) on human acetylcholinesterase (hAChE) ligand binding. In this respect, molecular dynamics simulations and our recently developed metadynamics method were applied to study the entrance of the three cations in the gorge of hAChE, and their effect on the dynamical motion of a ligand (tetramethylammonium) from the bulk of the solvent into the deep narrow enzyme gorge. Furthermore, in order to support the theoretical results, K(M) and k(cat) for the acetylcholine hydrolysis in the presence of the three cations were evaluated by using an approach based on the Ellman's method. The combination of computational and biochemical experiments clearly showed that Li(+), Na(+), and K(+) may influence the ligand binding at the hAChE gorge.     

Characterizing cultivable soil microbial communities from copper fungicide-amended olive orchard and vineyard soils

Use of copper-based fungicides has led to an increase in the total Cu content in agriculture soils. The focus of this study was to determine fractionation of Cu and to investigate the structure and the diversity of cultivable bacterial communities in two vineyards (one 25 years old and one 2 years old), one olive orchard and two forest soils. All soils developed on an Oligocene sandstone. The concentration of total Cu in the old vineyard (176.6 mg kg⁻¹) and olive orchard (145.5–296.7 mg kg⁻¹) was from 5 to 10 times higher than in forest soils. The major amount of Cu was found bound to the humic substances in cultivated soils, whereas in forest soils Cu was found in the residual mineral fraction. A relationship was found between the number of cultivable Cu-tolerant bacteria and total Cu content in soil. In the cultivated soils, Cu had a toxicological effect on bacterial community, and thereby Cu-levels > to 145 mg kg⁻¹ could be a risk to soil biota. Microbial communities were analysed by community level physiological profiling (CLPP), using the Biolog system, and by the amplified ribosomal DNA restriction analysis (ARDRA) approach. Only when cell suspensions containing 10⁴ colony-forming units (c.f.u.) were inoculated in each well of Biolog EcoPlates it was possible to discriminate microbial communities from different soil samples. As expected, 16S ARDRA showed that cultivated soils had a lower microbial diversity in respect to forest soils.     

Dinosaurs and the Cretaceous Terrestrial Revolution

The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125-80 Myr ago, when flowering plants, herbivorous and social insects, squamates, birds and mammals all underwent a rapid expansion. Although an apparent explosion of dinosaur diversity occurred in the mid-Cretaceous, coinciding with the emergence of new groups (e.g. neoceratopsians, ankylosaurid ankylosaurs, hadrosaurids and pachycephalosaurs), results from the first quantitative study of diversification applied to a new supertree of dinosaurs show that this apparent burst in dinosaurian diversity in the last 18 Myr of the Cretaceous is a sampling artefact. Indeed, major diversification shifts occurred largely in the first one-third of the group's history. Despite the appearance of new clades of medium to large herbivores and carnivores later in dinosaur history, these new originations do not correspond to significant diversification shifts. Instead, the overall geometry of the Cretaceous part of the dinosaur tree does not depart from the null hypothesis of an equal rates model of lineage branching. Furthermore, we conclude that dinosaurs did not experience a progressive decline at the end of the Cretaceous, nor was their evolution driven directly by the KTR.     

Deorphanisation of G protein-coupled receptors: A tool to provide new insights in nervous system pathophysiology and new targets for psycho-active drugs

G protein-coupled receptors represent the largest family of membrane receptors translating extracellular into intracellular signals. Endogenous ligands for these receptors range from physical stimuli (e.g., light and odorants) to ions and chemical transmitters, such as "classical" biogenic amines, nucleotides and peptides. Some of these receptors are pathologically altered in neurodegenerative and psychiatric diseases and indeed represent the target for a variety of already marketed psycho-active drugs. With the publication of the human genome, it has become evident that there still are many "orphan" G protein-coupled receptors, i.e., receptors responding to yet-unidentified endogenous ligands. A large amount of these receptors are expressed in nervous tissues, but, apart from their molecular structure, we have no information concerning their physiological roles and alterations in disease states. In this review, we summarise the advancements and pitfalls of the strategies that have been exploited in recent years to "deorphanise" some of these receptors. We also show how, in some cases, this deorphanisation process has resulted in the identification of new potential targets for drug development as well as in the discovery of previously unknown neurotransmitters, including bioactive peptides and substances that had been merely known as metabolic intermediates. We envisage that the deorphanisation of the remaining orphan G protein-coupled receptors will further advance our knowledge of nervous system pathophysiology and unveil additional targets for new therapeutic approaches to human diseases, including psychosis, depression, anxiety, pain and aging-associated neurodegenerative disorders.     

Pseudomonas pseudoalcaligenes KF707 upon biofilm formation on a polystyrene surface acquire a strong antibiotic resistance with minor changes in their tolerance to metal cations and metalloid oxyanions

The susceptibility to various biocides was examined in planktonic cells and biofilms of the obligate aerobe, PCBs degrader, Pseudomonas pseudoalcaligenes KF707. The toxicity of two antibiotics, amikacin and rifampicin, three metalloid oxyanions (AsO(2) (-), SeO(3) (2-), TeO(3) (2-)) and three metal cations (Cd(2+), Ni(2+), Al(3+)) was tested at two stages of the biofilm-development (4 and 24 h) and compared to planktonic cells susceptibility. Mature biofilms formed in rich (LB, Luria-Bertani) medium were thicker (23 mum) than biofilms grown in minimal (SA saccarose-arginine) medium (13 mum). Early grown (4 h) SA-biofilms, which consisted of a few sparse/attached cells, were 50-100 times more resistant to antibiotics than planktonic cells. Conversely, minor changes in tolerance to metal(loid)s were seen in both SA- and LB-grown biofilms. In contrast to planktonic cells, no reduction of TeO(3) (2-) to elemental Te(0) or SeO(3) (2-) to elemental Se(0) was seen in KF707 biofilms. The data indicate that: (a) metal tolerance in KF707 biofilms, under the growth and exposure conditions described here, is different than antibiotic tolerance; (b) KF707 planktonic cells and biofilms, are almost equally susceptible to killing by metal cations and oxyanions, and (c) biofilm-tolerance to TeO(3) (2-) and SeO(3) (2-) is not linked to metalloid reduction; this means that KF707 planktonic cells and biofilms differ in their physiology and strategy to counteract metalloid toxicity.     

Interactions in the error-prone postreplication repair proteins hREV1, hREV3, and hREV7

Most mutations after DNA damage in yeast Saccharomyces cerevisiae are induced by error-prone translesion DNA synthesis employing scRev1 and DNA polymerase zeta that consists of scRev3 and scRev7 proteins. Recently, the human REV1 (hREV1) and REV3 (hREV3) genes were identified, and their products were revealed to be involved in UV-induced mutagenesis, as observed for their yeast counterparts. Human REV7 (hREV7) was also cloned, and its product was found to interact with hREV3, but the biological function of hREV7 remained unknown. We report here the analyses of precise interactions in the human REV proteins. The interaction between hREV1 and hREV7 was identified by the yeast two-hybrid library screening using a bait of hREV7, which was confirmed by in vitro and in vivo binding assays. The homodimerization of hREV7 was also detected in the two-hybrid analysis. In addition, the precise domains for interaction between hREV7 and hREV1 or hREV3 and for hREV7 homodimerization were determined. Although hREV7 interacts with both hREV1 and hREV3, a stable complex formation of the three proteins was undetectable in vitro. These findings suggest the possibility that hREV7 might play an important role in regulating the enzymatic activities of hREV1 and hREV3 for mutagenesis in response to DNA damage.