Genome Analysis and Physiological Comparison of Alicycliphilus denitrificans Strains BC and K601T

The genomes of the Betaproteobacteria Alicycliphilus denitrificans strains BC and K601^T have been sequenced to get insight into the physiology of the two strains. Strain BC degrades benzene with chlorate as electron acceptor. The cyclohexanol-degrading denitrifying strain K601^T is not able to use chlorate as electron acceptor, while strain BC cannot degrade cyclohexanol. The 16S rRNA sequences of strains BC and K601^T are identical and the fatty acid methyl ester patterns of the strains are similar. Basic Local Alignment Search Tool (BLAST) analysis of predicted open reading frames of both strains showed most hits with Acidovorax sp. JS42, a bacterium that degrades nitro-aromatics. The genomes include strain-specific plasmids (pAlide201 in strain K601^T and pAlide01 and pAlide02 in strain BC). Key genes of chlorate reduction in strain BC were located on a 120 kb megaplasmid (pAlide01), which was absent in strain K601^T. Genes involved in cyclohexanol degradation were only found in strain K601^T. Benzene and toluene are degraded via oxygenase-mediated pathways in both strains. Genes involved in the meta-cleavage pathway of catechol are present in the genomes of both strains. Strain BC also contains all genes of the ortho-cleavage pathway. The large number of mono- and dioxygenase genes in the genomes suggests that the two strains have a broader substrate range than known thus far.     

Acute Mechanical Stretch Promotes eNOS Activation in Venous Endothelial Cells Mainly via PKA and Akt Pathways

In the vasculature, physiological levels of nitric oxide (NO) protect against various stressors, including mechanical stretch. While endothelial NO production in response to various stimuli has been studied extensively, the precise mechanism underlying stretch-induced NO production in venous endothelial cells remains incompletely understood. Using a model of continuous cellular stretch, we found that stretch promoted phosphorylation of endothelial NO synthase (eNOS) at Ser¹¹⁷⁷, Ser⁶³³ and Ser⁶¹⁵ and NO production in human umbilical vein endothelial cells. Although stretch activated the kinases AMPKα, PKA, Akt, and ERK1/2, stretch-induced eNOS activation was only inhibited by kinase-specific inhibitors of PKA and PI3K/Akt, but not of AMPKα and Erk1/2. Similar results were obtained with knockdown by shRNAs targeting the PKA and Akt genes. Furthermore, inhibition of PKA preferentially attenuated eNOS activation in the early phase, while inhibition of the PI3K/Akt pathway reduced eNOS activation in the late phase, suggesting that the PKA and PI3K/Akt pathways play distinct roles in a time-dependent manner. Finally, we investigated the role of these pathways in stretch-induced endothelial exocytosis and leukocyte adhesion. Interestingly, we found that inhibition of the PI3K/Akt pathway increased stretch-induced Weibel-Palade body exocytosis and leukocyte adhesion, while inhibition of the PKA pathway had the opposite effects, suggesting that the exocytosis-promoting effect of PKA overwhelms the inhibitory effect of PKA-mediated NO production. Taken together, the results suggest that PKA and Akt are important regulators of eNOS activation in venous endothelial cells under mechanical stretch, while playing different roles in the regulation of stretch-induced endothelial exocytosis and leukocyte adhesion.     

Characterization of saponins and phenolic compounds: antioxidant activity and inhibitory effects on α-glucosidase in different varieties of colored quinoa (Chenopodium quinoa Willd)

ABSTRACT

This study investigated the contents of saponins and phenolic compounds in relation to their antioxidant activity and α-glucosidase inhibition activity of 7 colored quinoa varieties. The total saponin content was significantly different among 7 varieties and ranged from 7.51 to 12.12 mg OAE/g DW. Darker quinoa had a higher content of phenolic compounds, as well as higher flavonoids and antioxidant activity than that of light varieties. Nine individual phenolic compounds were detected in free and bound form, with gallic acid and ferulic acid representing the major compounds. The free and bound phenolic compounds (gallic acid and ferulic acid in particular) exhibited high linear correlation with their corresponding antioxidant values. In addition, the free phenolic extracts from colored quinoa exhibited higher inhibitory activity against α-glucosidase than the bound phenolic extracts. These findings imply that colored quinoa with abundant bioactive phytochemicals could be an important natural source for preparing functional food.     

Oxygen isotope temperature calibrations for modern Tridacna shells in western Pacific

Coral Reefs - The oxygen isotope ratio of carbonate in Tridacna shell (δ18Oshell) is assumed to be precipitated in isotopic equilibrium with surrounding seawater and thus reflects a...     

Antidiabetic potential of oleanolic acid from Ligustrum lucidum Ait

Ligustrum lucidum Ait. has been used in traditional Chinese medicine for over 1000 years because of its anti-tumor, antimutagenic, antidiabetic, and hepatoprotective properties. The aim of this study was to determine whether oleanolic acid (OA) is the principal active compound of L. lucidum responsible for its antidiabetic properties, and to examine its effect on the expression of thyroid hormones and insulin secretion, thus revealing the mechanism by which L. lucidum modulates insulin levels in diabetes. When rats with streptozotocin-induced diabetes were treated with OA (100 and 200 mg/kg body mass per day, for 40 days), the changes in blood glucose levels and in oral glucose tolerance tests showed that hypoglycemia was more pronounced in OA-treated groups than in the diabetic control rats, and that the levels of triglyceride, total cholesterol, and low-density lipoportein cholesterol in OA-treated rats were lower than those in the diabetic control rats, whose high-density lipoprotein cholesterol increased. OA-treated rats also gained weight, and exhibited increased serum insulin levels. In contrast, OA treatment did not effect the levels of thyroid hormone or TSH in rats with streptozotocin-induced diabetes. These results indicate that OA has hypoglycemic and hypolipidemic effects. OA treatment might stimulate insulin release, and consequently, results in the modulation of glucose levels and regulation of lipid metabolism.     

Elucidation of 2-hydroxybiphenyl effect on dibenzothiophene desulfurization by Microbacterium sp. strain ZD-M2

The effect of 2-hydroxybiphenyl (2-HBP), the end product of dibenzothiophene (DBT) desulfurization via 4S pathway, on cell growth and desulfurization activity was investigated by Microbacterium sp. The experimental results indicate that 2-HBP would inhibit the desulfurization activity. Providing 2-HBP was added in the reaction media, the DBT degradation rate decreased along with the increase of 2-HBP addition. By contrast, cell growth would be promoted in the addition of 2-HBP at a low concentration (<0.1mM). At high concentration of 2-HBP, the inhibition on the cell growth occurred. Meanwhile, the inhibitory effect of 2-HBP on DBT desulfurization activity was tested both in the oil/aqueous two-phase system and the aqueous system. A mathematical model was developed to explain the product formation kinetics with DBT as the sole sulfur source. The predicted results were close to the experimental data, it elucidated that along with the 2-HBP accumulation, the inhibitory effect of 2-HBP on DBT desulfurization and cell growth was enhanced.     

Rad9 plays an important role in DNA mismatch repair through physical interaction with MLH1

Rad9 is conserved from yeast to humans and plays roles in DNA repair (homologous recombination repair, and base-pair excision repair) and cell cycle checkpoint controls. It has not previously been reported whether Rad9 is involved in DNA mismatch repair (MMR). In this study, we have demonstrated that both human and mouse Rad9 interacts physically with the MMR protein MLH1. Disruption of the interaction by a single-point mutation in Rad9 leads to significantly reduced MMR activity. This disruption does not affect S/M checkpoint control and the first round of G₂/M checkpoint control, nor does it alter cell sensitivity to UV light, gamma rays or hydroxyurea. Our data indicate that Rad9 is an important factor in MMR and carries out its MMR function specifically through interaction with MLH1.     

Genome sequence of Thermotoga sp. strain RQ2, a hyperthermophilic bacterium isolated from a geothermally heated region of the seafloor near Ribeira Quente, the Azores

Thermotoga sp. strain RQ2 is probably a strain of Thermotoga maritima. Its complete genome sequence allows for an examination of the extent and consequences of gene flow within Thermotoga species and strains. Thermotoga sp. RQ2 differs from T. maritima in its genes involved in myo-inositol metabolism. Its genome also encodes an apparent fructose phosphotransferase system (PTS) sugar transporter. This operon is also found in Thermotoga naphthophila strain RKU-10 but no other Thermotogales. These are the first reported PTS transporters in the Thermotogales.