Effect of Anionic Salt and Highly Fermentable Carbohydrate Supplementations on Urine pH and on Experimentally Induced Hypocalcaemia in Cows

The objective of this experiment was to determine the effect of dietary grain on calcium homeostasis. Six rumen-fistulated dairy cows with 3 or more previous lactations and no history of parturient paresis were randomly assigned to a sequence of diets in a crossover study with 4 periods of 10 days each. Dietary treatments were: A control ration consisting of wrap grass silage alone (1), the control ration supplemented with ammonium chloride and ammonium sulphate salt solution (2), control ration following a period with supplementation (3) and control ration supplemented with increasing amounts of barley from 4 to 10 kg/cow per day, expected to produce subclinical rumen acidosis (4). Daily intake of the diets was adjusted to 14 kg DM/cow per day. On day 11, the calcium-regulating mechanisms in cows were challenged until recumbency by a standardized intravenous EDTA infusion and cows were left to recover spontaneously. Anion supplementation and the feeding of highly fermentable carbohydrate lowered urine pH below 7.0 due to subclinical acidosis. During spontaneous recovery from EDTA induced hypocalcaemia, the cows more quickly regained a whole blood free calcium concentration of 1.00 mmol/L if they had most recently been supplemented with either anionic salts or with increasing amounts of barley, as compared to the basic ration. It is concluded that so-called slug-feeding or 'steaming up' with highly fermentable carbohydrates before parturition in milk fever susceptible cows enhanced calcium homeostasis similar to the effect seen in cows on anionic diets.     

Evolution of the Sry genes

Existing DNA sequence data on the Sry gene, the mammalian sex- determining locus in the Y chromosome, were analyzed for primates, rodents, and bovids. In all three taxonomic groups, the terminal sequences evolved faster than the HMG (high mobility group) boxes, and this applies both to synonymous (Ks) and nonsynonymous (Ka) nucleotide substitutions. Similar intragenic correlation between synonymous and nonsynonymous substitution rates was not found either in other mammalian genes that contain a conservative box (Sox, Msx) or in the MADS-box genes of plants. The rate of nonsynonymous substitutions exceeds significantly that of synonymous substitutions in the terminal Sry sequences of apes. We did not find good support for the hypothesis that the high evolutionary rate of Sry would be associated with a promiscuous mating system.      

Genetic and biochemical characterization of a pathway for the degradation of 2-aminoethylphosphonate in Sinorhizobium meliloti 1021

A variety of microorganisms have the ability to use phosphonic acids as sole sources of phosphorus. Here, a novel pathway for degradation of 2-aminoethylphosphonate in the bacterium Sinorhizobium meliloti 1021 is proposed based on the analysis of the genome sequence. Gene deletion experiments confirmed the involvement of the locus containing phnW, phnA, and phnY genes in the conversion of 2-aminoethylphosphonate to inorganic phosphate. Biochemical studies of the recombinant PhnY and PhnA proteins verified their roles as phosphonoacetaldehyde dehydrogenase and phosphonoacetate hydrolase, respectively. This pathway is likely not limited to S. meliloti as suggested by the presence of homologous gene clusters in other bacterial genomes.     

Benzothiophene inhibitors of MK2. Part 1: Structure–activity relationships,assessments of selectivity and cellular potency

Identification of potent benzothiophene inhibitors of mitogen activated protein kinase-activated protein kinase 2 (MK2), structure–activity relationship (SAR) studies, selectivity assessments against CDK2, cellular potency and mechanism of action are presented. Crystallographic data provide a rationale for the observed MK2 potency as well as selectivity over CDK2 for this class of inhibitors.     

The structure of a Staphylococcus aureus leucocidin component (LukF-PV) reveals the fold of the water-soluble species of a family of transmembrane pore-forming toxins.

BACKGROUND: Leucocidins and gamma-hemolysins are bi-component toxins secreted by Staphylococcus aureus. These toxins activate responses of specific cells and form lethal transmembrane pores. Their leucotoxic and hemolytic activities involve the sequential binding and the synergistic association of a class S and a class F component, which form hetero-oligomeric complexes. The components of each protein class are produced as non-associated, water-soluble proteins that undergo conformational changes and oligomerization after recognition of their cell targets. RESULTS: The crystal structure of the monomeric water-soluble form of the F component of Panton-Valentine leucocidin (LukF-PV) has been solved by the multiwavelength anomalous dispersion (MAD) method and refined at 2.0 A resolution. The core of this three-domain protein is similar to that of alpha-hemolysin, but significant differences occur in regions that may be involved in the mechanism of pore formation. The glycine-rich stem, which undergoes a major rearrangement in this process, forms an additional domain in LukF-PV. The fold of this domain is similar to that of the neurotoxins and cardiotoxins from snake venom. CONCLUSIONS: The structure analysis and a multiple sequence alignment of all toxic components, suggest that LukF-PV represents the fold of any water-soluble secreted protein in this family of transmembrane pore-forming toxins. The comparison of the structures of LukF-PV and alpha-hemolysin provides some insights into the mechanism of transmembrane pore formation for the bi-component toxins, which may diverge from that of the alpha-hemolysin heptamer.     

Influence of nanofibers on growth and gene expression of human tendon derived fibroblast

Background  

Rotator cuff tears are a common and frequent lesion especially in older patients. The mechanisms of tendon repair are not fully understood. Common therapy options for tendon repair include mini-open or arthroscopic surgery. The use of growth factors in experimental studies is mentioned in the literature. Nanofiber scaffolds, which provide several criteria for the healing process, might be a suitable therapy option for operative treatment. The aim of this study was to explore the effects of nanofiber scaffolds on human tendon derived fibroblasts (TDF's), as well as the gene expression and matrix deposition of these fibroblasts.     

The molecular puzzle of two-component signaling cascades

Two-component systems constitute prevalent signaling pathways in bacteria and mediate a large variety of adaptative cellular responses. Signaling proceeds through His-Asp phosphorelay cascades that involve two central partners, the histidine protein kinase and the response regulator protein. Structural studies have provided insights into some design principles and activation mechanisms of these multi-domain proteins implicated in the control of virulence gene expression in several pathogens.     

New Insights on the Mechanism of Quinoline-based DNA Methyltransferase Inhibitors

Among the epigenetic marks, DNA methylation is one of the most studied. It is highly deregulated in numerous diseases, including cancer. Indeed, it has been shown that hypermethylation of tumor suppressor genes promoters is a common feature of cancer cells. Because DNA methylation is reversible, the DNA methyltransferases (DNMTs), responsible for this epigenetic mark, are considered promising therapeutic targets. Several molecules have been identified as DNMT inhibitors and, among the non-nucleoside inhibitors, 4-aminoquinoline-based inhibitors, such as SGI-1027 and its analogs, showed potent inhibitory activity. Here we characterized the in vitro mechanism of action of SGI-1027 and two analogs. Enzymatic competition studies with the DNA substrate and the methyl donor cofactor, S-adenosyl-l-methionine (AdoMet), displayed AdoMet non-competitive and DNA competitive behavior. In addition, deviations from the Michaelis-Menten model in DNA competition experiments suggested an interaction with DNA. Thus their ability to interact with DNA was established; although SGI-1027 was a weak DNA ligand, analog 5, the most potent inhibitor, strongly interacted with DNA. Finally, as 5 interacted with DNMT only when the DNA duplex was present, we hypothesize that this class of chemical compounds inhibit DNMTs by interacting with the DNA substrate.