New positive regulators of lin-12 activity in Caenorhabditis elegans include the BRE-5/Brainiac glycosphingolipid biosynthesis enzyme

Screens for suppressors of lin-12 hypermorphic alleles in C. elegans have identified core components and modulators of the LIN-12/Notch signaling pathway. Here we describe the recovery of alleles of six new genes from a screen for suppressors of the egg-laying defect associated with elevated lin-12 activity. The molecular identification of one of the new suppressor genes revealed it as bre-5, which had previously been identified in screens for mutations that confer resistance to Bt toxin in C. elegans. bre-5 is the homolog of D. melanogaster brainiac. BRE-5/Brainiac catalyzes a step in the synthesis of glycosphingolipids, components of lipid rafts that are thought to act as platforms for association among certain kinds of membrane-bound proteins. Reducing the activity of several other genes involved in glycosphingolipid biosynthesis also suppresses the effects of constitutive lin-12 activity. Genetic analysis and cell ablation experiments suggest that bre-5 functions prior to ligand-induced ectodomain shedding that activates LIN-12 for signal transduction.     

Reduced expression of the NADPH oxidase NOX4 is a hallmark of adipocyte differentiation

Adipocyte differentiation is a complex process regulated among other factors by insulin and the production of reactive oxygen species (ROS). NOX4 is a ROS generating NADPH oxidase enzyme mediating insulin's action in 3T3L1 adipocytes. In the present paper we show that NOX4 is expressed at high levels both in white and brown preadipocytes and that differentiation into adipocytes results in a decrease in their NOX4 mRNA content. These in vitro results were confirmed in vivo by demonstrating that in intact adipose tissue the majority of NOX4 expressing cells are localized within the preadipocyte containing stromal/vascular fraction, rather than in the portion consisting of mature adipocytes. In line with these observations, quantification of NOX4 mRNA in fat derived from different rodent models of insulin resistance indicated that alteration in NOX4 expression reflects changes in the ratio of adipocyte/interstitial fractions. In conclusion, we reveal that decreased NOX4 mRNA content is a hallmark of adipocyte differentiation and that NOX4 expression measured in whole adipose tissue is not an unequivocal indicator of intact or impaired insulin action.     

Antarctic desert soil bacteria exhibit high novel natural product potential,evaluated through long-read genome sequencing and comparative genomics

Actinobacteria and Proteobacteria are important producers of bioactive natural products (NP), and these phyla dominate in the arid soils of Antarctica, where metabolic adaptations influence survival under harsh conditions. Biosynthetic gene clusters (BGCs) which encode NPs, are typically long and repetitious high G + C regions difficult to sequence with short-read technologies. We sequenced 17 Antarctic soil bacteria from multi-genome libraries, employing the long-read PacBio platform, to optimize capture of BGCs and to facilitate a comprehensive analysis of their NP capacity. We report 13 complete bacterial genomes of high quality and contiguity, representing 10 different cold-adapted genera including novel species. Antarctic BGCs exhibited low similarity to known compound BGCs (av. 31%), with an abundance of terpene, non-ribosomal peptide and polyketide-encoding clusters. Comparative genome analysis was used to map BGC variation between closely related strains from geographically distant environments. Results showed the greatest biosynthetic differences to be in a psychrotolerant Streptomyces strain, as well as a rare Actinobacteria genus, Kribbella, while two other Streptomyces spp. were surprisingly similar to known genomes. Streptomyces and Kribbella BGCs were predicted to encode antitumour, antifungal, antibacterial and biosurfactant-like compounds, and the synthesis of NPs with antibacterial, antifungal and surfactant properties was confirmed through bioactivity assays.     

The mammalian INO80 chromatin remodeling complex is required for replication stress recovery

A number of studies have implicated the yeast INO80 chromatin remodeling complex in DNA replication, but the function of the human INO80 complex during S phase remains poorly understood. Here, we have systematically investigated the involvement of the catalytic subunit of the human INO80 complex during unchallenged replication and under replication stress by following the effects of its depletion on cell survival, S-phase checkpoint activation, the fate of individual replication forks, and the consequences of fork collapse. We report that INO80 was specifically needed for efficient replication elongation, while it was not required for initiation of replication. In the absence of the Ino80 protein, cells became hypersensitive to hydroxyurea and displayed hyperactive ATR-Chk1 signaling. Using bulk and fiber labeling of DNA, we found that cells deficient for Ino80 and Arp8 had impaired replication restart after treatment with replication inhibitors and accumulated double-strand breaks as evidenced by the formation of γ-H2AX and Rad51 foci. These data indicate that under conditions of replication stress mammalian INO80 protects stalled forks from collapsing and allows their subsequent restart.     

Mechanisms of directional asymmetry in the zebrafish epithalamus

The epithalamus of zebrafish presents the best-studied case of directional asymmetry in the vertebrate brain. Epithalamic asymmetries are coupled to visceral asymmetry and include left-sided migration of a single midline structure (the parapineal organ) and asymmetric differentiation of paired bilateral nuclei (habenulae). The mechanisms underlying the establishment of epithalamic asymmetry involve the interplay between anti-symmetry and laterality signals to guide asymmetric parapineal migration. This event triggers the amplification of habenular asymmetries and the subsequent organisation of lateralised circuits in the interpeduncular nucleus. This review will summarise our current understanding on these processes and propose a sequential modular organisation of the events controlling the development of asymmetry along the parapineal–habenular–interpeduncular axis.     

Synthesis of cinnamoyl and hydroxycinnamoyl amino acid conjugates and evaluation of their antioxidant activity.

Fifteen amides of cinnamic, ferulic and sinapic acids with natural and unnatural C-protected amino acids have been synthesized. The amides (E)-N-(feruloyl)-L-tyrosine methyl ester (10), (E)-N-(feruloyl)-L-phenylalanine t-butyl ester (11), (E)-N-(sinapoyl)-L-tyrosine methyl ester (13) and (E)-N-(sinapoyl)-L-phenylalanine t-butyl ester (15) with a free carboxyl group of amino acids have been found in nature. The rest of the compounds are unknown. The hydroxycinnamoyl amino acid conjugates have been studied for their antioxidant activity (AOA) in bulk phase lipid autoxidation. The highest AOA has been found for the compounds 11 and 15, which contain the same phenylalanine moiety.     

Oxidase activity of ceruloplasmin and concentrations of copper and zinc in serum in chronic arterial occlusion of the lower limbs.

The presence of ischaemic tissue excites an inflammatory reaction and synthesis of acute phase proteins (APhPs). Ceruloplasmin (Cp) protein binds 90% of the copper in plasma and it is one of the positive APhPs, and its concentration increases in infection, inflammation or necrosis. The study presents the relationship of the oxidase activity of Cp and concentrations of Cu and Zn in serum of men with different degrees of ischaemia of the lower limbs. The subjects were 32 men with chronic arterial occlusion (AO) of the lower limbs. The oxidase activity of Cp was measured in serum with o-dianisidine as a substrate. Concentrations of Cu and Zn were determined by using atomic absorption spectrometry. The mean activity of Cp in serum in AO (173 +/- 69.2 U/l) was higher as compared with the control group (123.7 +/- 28.6 U/l), and in men with critical ischaemia (> or = 194.8 U/l) than in men with a moderate level of ischaemia (109.3 +/- 31.6 U/l). The mean concentrations of Cu and Zn in serum were found to be higher in AO (22.2 +/- 4.2 and 19.1 +/- 6.9 mumol/l, respectively) than in the control group (16.3 +/- 1.8 and 15.2 +/- 2.3 mumol/l), and in men with critical ischaemia (> or = 22.2 and 19.1 mumol/l) than in men with a moderate level of ischaemia (18.5 +/- 3.3 and 14.5 +/- 4.3 mumol/l). Significant positive correlation coefficients were calculated for the activities of Cp and concentrations of Cu in the control group (r = 0.86) and the AO group (r = 0.76), and low, but significant, correlations for Cp and Zn in the AO group (r = 0.66). The increase in the oxidase activity of Cp and concentration of Cu in serum in ischaemia is caused by the acute phase response. The relationship of Zn concentration and Cp activity in ischaemia is indirect and needs further study.