Genetic and biochemical evidence for involvement of HOTHEAD in the biosynthesis of long-chain α-,ω-dicarboxylic fatty acids and formation of extracellular matrix

In plants, extracellular matrix polymers built from polysaccharides and cuticular lipids have structural and protective functions. The cuticle is found to be ten times thinner in Arabidopsis thaliana (L.) Heynh than in many other plants, and there is evidence that it is unusual in having a high content of α-,ω-dicarboxylic fatty acids (FAs) in its polyesters. We designated the new organ fusion mutant hth-12 after it appeared to be allelic to adhesion of calyx edges (ace) and hothead (hth), upon molecular cloning of the gene by transposon tagging. This mutant is deficient in its ability to oxidize long-chain ω-hydroxy FAs to ω-oxo FAs, which results in leaf polyesters in decreased α-,ω-dicarboxylic FAs and increased ω-hydroxy FAs. These chemical phenotypes lead to disorder of the cuticle membrane structure in hth-12. ACE/HTH is a single-domain protein showing sequence similarity to long-chain FA ω-alcohol dehydrogenases from Candida species, and we hypothesize that it may catalyze the next step after cytochrome P450 FA ω-hydroxylases in the ω-oxidation pathway. We show that ACE/HTH is specifically expressed in epidermal cells. It appears very likely therefore that the changes in the amount of α-,ω-dicarboxylic FAs in hth-12 reflect the different composition of cuticular polyesters. The ACE/HTH gene is also expressed in root epidermal cells which do not form a polyester membrane on the exterior surface, thereby making it possible that the end products of the pathway, α-,ω-dicarboxylic FAs, are generally required for the cross-linking that ensures the integrity of the outer epidermal cell wall.     

Analysis of monomeric mutants of HSC70: a possible relationship between oligomerization and functional properties

Data of this study showed that alphaD-alphaE helices and the conserved interdomain linker are two interfaces essential not only for the self-association but also for the functional properties of rat HSC70. Self-association which is a conserved property of HSP70 seems to be important for the activity of these proteins.     

Influence of the extraction solvent on antioxidant activity of Althaea officinalis L. root extracts

Althaea officinalis (Malvaceae) is a well-known plant that is widely distributed throughout the world. Aqueous and hydroalcoholic extracts from A. officinalis root are used mainly because of their antitussive and expectorant activity. It is well known that these activities are based on the polysaccharide composition, but little is known about the possible antioxidant activity of root extract. The present study evaluated antioxidant activity of root extracts prepared with different extraction solvents applying ABTS^·+ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), hypochlorous acid scavenging assay and iron-induced lipid peroxidation. The results showed that the extract prepared with water as extraction solvent did not possess antioxidant activity, whereas the extracts obtained using ethanol:water as extraction agent showed well pronounced antioxidant activity. In particular, the extracts obtained at low concentration of ethanol in the mixed solvent (50:50 and 70:30, v/v) showed higher scavenging activity for ABTS^·+ radicals and hypochlorite ions than the extract obtained with the higher ethanol concentration (90:10, v/v). These results correlated very well with phenolic and flavonoid content of the extracts. The extracts did not show cytotoxic effect on human BV-173 leukemic cells but may have immunomodulating effects due to their antioxidant properties.     

Stevens-Johnson Syndrome Associated with Drugs and Vaccines in Children: A Case-Control Study

Objective

Stevens-Johnson Syndrome (SJS) is one of the most severe muco-cutaneous diseases and its occurrence is often attributed to drug use. The aim of the present study is to quantify the risk of SJS in association with drug and vaccine use in children.

Methods

A multicenter surveillance of children hospitalized through the emergency departments for acute conditions of interest is currently ongoing in Italy. Cases with a diagnosis of SJS were retrieved from all admissions. Parents were interviewed on child’s use of drugs and vaccines preceding the onset of symptoms that led to the hospitalization. We compared the use of drugs and vaccines in cases with the corresponding use in a control group of children hospitalized for acute neurological conditions.

Results

Twenty-nine children with a diagnosis of SJS and 1,362 with neurological disorders were hospitalized between 1^st November 1999 and 31^st October 2012. Cases were more frequently exposed to drugs (79% vs 58% in the control group; adjusted OR 2.4; 95% CI 1.0–6.1). Anticonvulsants presented the highest adjusted OR: 26.8 (95% CI 8.4–86.0). Significantly elevated risks were also estimated for antibiotics use (adjusted OR 3.3; 95% CI 1.5–7.2), corticosteroids (adjusted OR 4.2; 95% CI 1.8–9.9) and paracetamol (adjusted OR 3.2; 95% CI 1.5–6.9). No increased risk was estimated for vaccines (adjusted OR: 0.9; 95% CI 0.3–2.8).

Discussion

Our study provides additional evidence on the etiologic role of drugs and vaccines in the occurrence of SJS in children.     

The Pluripotency Factor-Bound Intron 1 of Xist Is Dispensable for X Chromosome Inactivation and Reactivation In Vitro and In Vivo

Download : Download video (91MB)     

Genetic Aspects of Myoclonus–Dystonia Syndrome (MDS)

Myoclonus–dystonia (M–D) is an autosomal-dominant movement disorder with onset in the first two decades of life. Mutations in the epsilon-sarcoglycan gene (SGCE, DYT11) on chromosome 7q21–q31 represent the major genetic cause of M–D in some populations. The syndrome was related with mutations in two other genes (DRD2 and DYT1). A second locus has been reported in one large M–D family (DYT15, 18p11), but no gene has been identified yet. In this review, we discuss genetic aspects of myoclonus–dystonia.     

Protein Phosphatases 2C Regulate the Activation of the Snf1-Related Kinase OST1 by Abscisic Acid in Arabidopsis

The plant hormone abscisic acid (ABA) orchestrates plant adaptive responses to a variety of stresses, including drought. This signaling pathway is regulated by reversible protein phosphorylation, and genetic evidence demonstrated that several related protein phosphatases 2C (PP2Cs) are negative regulators of this pathway in Arabidopsis thaliana. Here, we developed a protein phosphatase profiling strategy to define the substrate preferences of the HAB1 PP2C implicated in ABA signaling and used these data to screen for putative substrates. Interestingly, this analysis designated the activation loop of the ABA activated kinase OST1, related to Snf1 and AMPK kinases, as a putative HAB1 substrate. We experimentally demonstrated that HAB1 dephosphorylates and deactivates OST1 in vitro. Furthermore, HAB1 and the related PP2Cs ABI1 and ABI2 interact with OST1 in vivo, and mutations in the corresponding genes strongly affect OST1 activation by ABA. Our results provide evidence that PP2Cs are directly implicated in the ABA-dependent activation of OST1 and further suggest that the activation mechanism of AMPK/Snf1-related kinases through the inhibition of regulating PP2Cs is conserved from plants to human.