Search

Bacterial adsorption on mineral surface is one of the key steps in bioleaching process. The bacteria adsorb on the mineral surface via the extracellular polymeric substances (EPS) layer. In this paper, the behavior of glucuronic acid, one of the key substances in EPS layer, adsorbed on the pyrite surface is studied using DFT and electrochemical methods. Adsorption capacity of glucuronic acid is stronger than that of water. Glucuronic acid adsorbs on pyrite surfaces and it follows a mixed type of interactions (physisorption and chemisorption). Adsorption of glucuronic acid on pyrite surface followed Langmuir’s adsorption isotherm with adsorption standard free energy of –27.67kJ mol–1. The structural and electronic parameters were calculated and discussed.

The gut microbiota is closely associated with osteoporosis, but its specific mechanisms of action have not been fully elucidated. Short-chain fatty acids (SCFAs), produced by the fermentation of complex carbohydrates, are key regulatory metabolites produced by the gut microbiota and play an important role in the regulation of various systems by the gut microbiota. In recent years, SCFAs have been found to be a key link between the gut microbiota and bone. SCFAs can affect bone metabolism by affecting the integrity of the intestinal mucosal barrier, regulating G protein-coupled receptors and inhibiting histone deacetylase activity etc. SCFAs are currently the focus of research, but the mechanisms of interaction between SCFAs and osteoporosis in China are less reported. This paper reviews the role of gut microbiota and its metabolites, SCFAs, as well as the research progress of SCFAs affecting osteoporosis, with the aim of providing innovative therapeutic opportunities for bone metabolic diseases. [ABSTRACT FROM AUTHOR]

Low temperature is a major environmental constraint on the production of apples worldwide. An apple rootstock with high cold tolerance was selected to identify genes related to stress tolerance. The transcriptional profiles of the genes in the leaves were examined after various intervals of exposure to cold stress. We obtained three libraries of 14,219, 11,176 and 16,116 tag-mapped predicted coding sequences at three time points (0, 1 and 6 h) during cold stress. In the two time periods, which were from 0 to 1 h and from 1 to 6 h, 139 and 1,085 genes were upregulated, and 1,499 and 381 genes were downregulated, respectively. These groups included a large number of unknown genes. The distribution of genes indicated cold adaptation in the plant. Most of the differential expression genes (DEGs) had temporal specificity and significantly different expression changes at different time points. The classification of DEGs by GO category and KEGG pathway analysis revealed that the DEGs are involved in numerous biological pathways, including metabolism, plant-pathogen interaction and signal transduction. Eleven randomly selected tag-mapped genes were examined by qRT-PCR. The results of the qRT-PCR were in accordance with the transcriptional profiles. The most upregulated gene (MDP0000198054) from 0 to 1 h encodes a dehydration-responsive element-binding protein/C-repeat factor (DREB/CBF). In this study, MDP0000198054 and related genes involved in the cold stress response were discussed. These results could provide new insights into the stress tolerance mechanisms of apple rootstocks. [ABSTRACT FROM AUTHOR]

Vitamin K epoxide reductase (VKOR) exists widely in the chloroplasts of higher plants and plays important roles in redox regulation. However, investigations of plant VKOR function have primarily focused on VKOR from Arabidopsis, and knowledge concerning this function is therefore quite limited. In this study, Solanum lycopersicum was used to study the function of VKOR. Transcription level analysis revealed that SlVKOR (S. lycopersicum VKOR) expression was upregulated by salt or drought stress. To further investigate the function of SlVKOR in plants, we generated sense and antisense transgenic S. lycopersicum homozygotes at T2 generation plants. Compared with wild-type (WT) plants, the leaf disks of the SlVKOR overexpression plants retained a much higher percentage of chlorophyll after salt or drought treatment, whereas the antisense transgenic plants displayed an opposite response. The overexpressed plants displayed lower levels of H2O2 and superoxide anion radical (O2(·-)) than WT plants, whereas antisense plants accumulated considerably more H2O2 and O2(·-). The activities of reactive oxygen scavenger enzymes, including superoxide dismutase, peroxidase, ascorbate peroxidase and catalase, were consistent with the accumulation of reactive oxygen species. Based on these results, we suggest that SlVKOR is involved in resistance to salt or drought stress., (© 2015 Scandinavian Plant Physiology Society.)

Arabidopsis lumen thiol oxidoreductase 1 (LTO1) - the At4g35760 gene product - was previously found to be related to reactive oxygen species (ROS) accumulation. Here, we show that ROS accumulated in a mutant Arabidopsis line (lto1-2, mutant of LTO1/AtVKOR) under osmotic stress at a higher level than that observed in wild-type and transgenic complemented plants of the lto1-2 mutant (lto1-2C, transgenic complemented plants of lto1-2). Because ROS accumulation in osmotic stress is triggered by abscisic acid (ABA), an ABA-responsive gene, Annexin 1 (AnnAt1), was selected to study the response. Osmotic stress or exogenous ABA can significantly upregulate the transcription of AnnAt1 in wild-type and lto1-2C plants. Only a slight change in the transcriptional abundance of AnnAt1 was observed under osmotic stress in the lto1-2 mutant, but exogenous ABA application could increase the expression of AnnAt1, which suggested that exogenous ABA had a partial complementation role. Because the transcription of AnnAt1 is regulated by ABRE (ABA-responsive elements) binding proteins (AREBs)/ABRE binding factors (ABFs), the expression of AREBs/ABFs was also analyzed. The transcription of AREBs/ABFs in the lto1-2 mutant was not induced by osmotic stress but was significantly upregulated by exogenous ABA, which significantly differs from the wild-type and lto1-2C plant responses. Similarly, the expression of another ABA-responsive gene, RD29B (responsive to desiccation stress gene 29B), in the lto1-2 mutant was also upregulated by exogenous ABA. The partial complementation of mutants by ABA indicated that the ABA signal transduction pathway was not significantly affected in the lto1-2 mutant. Taken together, these results suggest that LTO1 is involved in ABA-mediated response to osmotic stress, possibly by affecting the biosynthesis of endogenous ABA., (© 2014 Scandinavian Plant Physiology Society.)