nMAT4, a maturase factor required for nad1 pre‐mRNA processing and maturation,is essential for holocomplex I biogenesis in Arabidopsis mitochondria

Group II introns are large catalytic RNAs that are found in bacteria and organellar genomes of lower eukaryotes, but are particularly prevalent within mitochondria in plants, where they are present in many critical genes. The excision of plant mitochondrial introns is essential for respiratory functions, and is facilitated in vivo by various protein cofactors. Typical group II introns are classified as mobile genetic elements, consisting of the self‐splicing ribozyme and its own intron‐encoded maturase protein. A hallmark of maturases is that they are intron‐specific, acting as cofactors that bind their intron‐containing pre‐RNAs to facilitate splicing. However, the degeneracy of the mitochondrial introns in plants and the absence of cognate intron‐encoded maturase open reading frames suggest that their splicing in vivo is assisted by ‘trans’‐acting protein factors. Interestingly, angiosperms harbor several nuclear‐encoded maturase‐related (nMat) genes that contain N‐terminal mitochondrial localization signals. Recently, we established the roles of two of these paralogs in Arabidopsis, nMAT1 and nMAT2, in the splicing of mitochondrial introns. Here we show that nMAT4 (At1g74350) is required for RNA processing and maturation of nad1 introns 1, 3 and 4 in Arabidopsis mitochondria. Seed germination, seedling establishment and development are strongly affected in homozygous nmat4 mutants, which also show modified respiration phenotypes that are tightly associated with complex I defects.     

Dual-color bioluminescent assay using infected HepG2 cells sheds new light on Chlamydia pneumoniae and human cytomegalovirus effects on human cholesterol 7α-hydroxylase (CYP7A1) transcription

Human bones, recovered from excavations, are an important biological archive of information. In particular, the analysis of the collagen fraction is useful for paleodietary reconstruction, via light stable isotopes, and for (14)C dating. Generally, collagen extraction procedures do not prevent loss of integrity of proteins. As a consequence, information about the state-of-remains preservation is unavailable. Here we describe a "soft" nondestructive CH(3)COOH-based method to recover collagen from archaeological bones, and also to obtain material for successive isotopic analyses. Our isotopic measurements on the extracts indicate that the CH(3)COOH-based method of extraction may be routinely employed in the context of paleodiet studies. In addition, we propose that biochemical characterization by denaturant electrophoresis and Western blot on CH(3)COOH extracts may be used as a bone collagen quality indicator.     

Epidemiology and risk factors associated with Anaplasma marginale infection of cattle in Peninsular Malaysia

Bovine anaplasmosis is a major concern to cattle farming in most parts of the world. Anaplasmosis negatively impacts the profitability of cattle farming by reducing the production, reproduction, and draft ability of cattle. Here, we report results from a one-year cross sectional study to determine the epidemiology and the risk factors for Anaplasma marginale infection of cattle in Peninsular Malaysia. Examination of one thousand and forty five blood samples of apparently healthy cattle from forty-three farms in all the states of Peninsular Malaysia by polymerase chain reaction (PCR) assay revealed an overall prevalence of A. marginale infection of cattle of 72.6%, showing high endemicity of this heamoprotozoan among cattle in the country. Cattle breeds, production type, herd owner, herd size, management system, farm size, farm age, prophylactic treatment against blood parasites, presence of ticks, frequency of deticking, zones, closeness to forest, closeness to waste area, closeness to human settlement and closeness to body of water were the risk factors significantly associated (P?<?0.05) with the detection of A. marginale in cattle. Results of this first molecular study on the epidemiology and risk factors for A. marginale infection of cattle from all the states of Peninsular Malaysia suggest policies and strategies for the prevention and control of the parasite to improve profitability of cattle farming in the country.     

FliZ induces a kinetic switch in flagellar gene expression

FliZ is an activator of class 2 flagellar gene expression in Salmonella enterica. To understand its role in flagellar assembly, we investigated how FliZ affects gene expression dynamics. We demonstrate that FliZ participates in a positive-feedback loop that induces a kinetic switch in class 2 gene expression.     

Colonization in an abandoned East-Mediterranean vineyard

Abstract. Previous studies on secondary succession in abandoned agricultural land in the Mediterranean area were carried out by the chronosequence method, including data from different sites. A unique opportunity to study secondary succession arose from a situation in which different parts of one homogeneous East-Mediterranean vineyard were abandoned for 5, 8, 15 and 35 yr, and did not suffer from any disturbance subsequently. Most of the perennial species that colonized the abandoned vineyard were fleshy fruited species, which apparently were dispersed by birds from the surrounding maquis into the vineyard. These bird-dispersed species were the first to be established, and were the dominant plant group according to dispersal modes. The abandoned vine plants and their supporting columns provided the birds with perching and feeding sites, enhancing the arrival of bird-dispersed species regardless of their life forms. Under these conditions the most important attribute that affected vegetation dynamics was seed dispersal mode. Trees were among the first to colonize in the vineyard, implying that no facilitation was needed for their establishment. Annual plant species were the only species to disappear during succession. Almost all perennial species which had arrived persisted in the vineyard, and no replacement of perennial species was found. The rate of succession was rapid, as expressed by the short time (8–15 yr) needed for the stabilization of species composition, for growth to average height of late succession trees, and for reaching high cover of the invading perennial species in the abandoned vineyard. The secondary succession described above differs from that in the western Mediterranean by the absence of perennial species replacement and its rapid rate. The possible causes are discussed.     

Ligand-binding specificities of laminin-binding integrins: a comprehensive survey of laminin-integrin interactions using recombinant alpha3beta1, alpha6beta1, alpha7beta1 and alpha6beta4 integrins.

The interactions of cells with basement membranes are primarily mediated via the engagement of laminins by a group of integrin family proteins, including integrins alpha3beta1, alpha6beta1, alpha7beta1 and alpha6beta4. To explore the ligand-binding specificities of these laminin-binding integrins, we produced these integrins, including two alpha7beta1 splice variants (alpha7X1beta1 and alpha7X2beta1), as soluble recombinant proteins and determined their binding specificities and affinities toward a panel of purified laminin isoforms containing distinct alpha chains. Among the five laminin-binding integrins investigated, alpha3beta1 and alpha6beta4 exhibited a clear specificity for laminin-332 (alpha3beta3gamma2) and laminin-511 (alpha5beta1gamma1)/521 (alpha5beta2gamma1), while integrin alpha6beta1 showed a broad specificity, binding to all laminin isoforms with a preference for laminin-111 (alpha1beta1gamma1), laminin-332 and laminin-511/521. The two alpha7beta1 variants were distinct from alpha3beta1, alpha6beta1 and alpha6beta4 in that they did not bind to laminin-332. alpha7X1beta1 bound to all laminins, except laminin-332, with a preference for laminin-211 (alpha2beta1gamma1)/221 (alpha2beta2gamma1) and laminin-511/521, while alpha7X2beta1 bound preferentially to laminin-111 and laminin-211/221. Laminin-511/521 was the most preferred ligand for all the laminin-binding integrins, except for alpha7X2beta1, whereas laminin-411 was the poorest ligand, capable of binding to alpha6beta1 and alpha7X1beta1 with only modest binding affinities. These comprehensive analyses of the interactions between laminin-binding integrins and a panel of laminins clearly demonstrate that the isoforms of both integrins and laminins differ in their binding specificities and affinities, and provide a molecular basis for better understanding of the adhesive interactions of cells with basement membranes of defined laminin compositions.     

Thrombin stimulates the expression of PDGF in lung epithelial cells

Several growth factors, including platelet-derived growth factor (PDGF), have been implicated in the mechanism of lung and airway remodeling. In the present study, we evaluated whether thrombin may promote lung and airway remodeling by increasing PDGF production from lung and airway epithelial cells. Conditioned medium (CM) was prepared by treating epithelial cells with increasing concentrations of thrombin; before use in the assays, CM was treated with hirudin until complete inhibition of thrombin activity. CM from epithelial cells stimulated the proliferation of lung fibroblasts and bronchial smooth muscle cells. Anti-PDGF antibody significantly inhibited this CM proliferative activity, implicating PDGF in this effect. Enzyme immunoassay and RT-PCR demonstrated that thrombin induced the secretion and expression of PDGF from bronchial and alveolar epithelial cells. RT-PCR showed that epithelial cells express the thrombin receptors protease-activated receptor (PAR)-1, PAR-3, and PAR-4. The PAR-1 agonist peptide was also found to induce PDGF secretion from epithelial cells, suggesting that the cellular effect of thrombin occurs via a PAR-1-mediated mechanism. Overall, this study showed for the first time that thrombin may play an important role in the process of lung and airway remodeling by stimulating the expression of PDGF via its cellular receptor, PAR-1.     

Fungal apoptosis: function, genes and gene function

Cells of all living organisms are programmed to self-destruct under certain conditions. The most well known form of programmed cell death is apoptosis, which is essential for proper development in higher eukaryotes. In fungi, apoptotic-like cell death occurs naturally during aging and reproduction, and can be induced by environmental stresses and exposure to toxic metabolites. The core apoptotic machinery in fungi is similar to that in mammals, but the apoptotic network is less complex and of more ancient origin. Only some of the mammalian apoptosis-regulating proteins have fungal homologs, and the number of protein families is drastically reduced. Expression in fungi of animal proteins that do not have fungal homologs often affects apoptosis, suggesting functional conservation of these components despite the absence of protein-sequence similarity. Functional analysis of Saccharomyces cerevisiae apoptotic genes, and more recently of those in some filamentous species, has revealed partial conservation, along with substantial differences in function and mode of action between fungal and human proteins. It has been suggested that apoptotic proteins might be suitable targets for novel antifungal treatments. However, implementation of this approach requires a better understanding of fungal apoptotic networks and identification of the key proteins regulating apoptotic-like cell death in fungi.     

S-glutathiolation of Ras mediates redox-sensitive signaling by angiotensin II in vascular smooth muscle cells

Angiotensin II (AII) increases production of reactive oxygen species from NAD(P)H oxidase, a response that contributes to vascular hypertrophy. Here we show in cultured vascular smooth muscle cells that S-glutathiolation of the redox-sensitive Cys(118) on the small GTPase, Ras, plays a critical role in AII-induced hypertrophic signaling. AII simultaneously increased the Ras activity and the S-glutathiolation of Ras (GSS-Ras) detected by biotin-labeled GSH or mass spectrometry. Both the increase in activity and GSS-Ras was labile under reducing conditions, suggesting the essential nature of this thiol modification to Ras activation. Overexpression of catalase, a dominant-negative p47(phox), or glutaredoxin-1 decreased GSS-Ras, Ras activation, p38, and Akt phosphorylation and the induction of protein synthesis by AII. Furthermore, expression of a Cys(118) mutant Ras decreased AII-mediated p38 and Akt phosphorylation as well as protein synthesis. These results show that H(2)O(2) from NAD(P)H oxidase forms GSS-Ras on Cys(118) and increases its activity leading to p38 and Akt phosphorylation, which contributes to the induction of protein synthesis. This study suggests that GSS-Ras is a redox-sensitive signaling switch that participates in the cellular response to AII.