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排序方式: 共有404条查询结果,搜索用时 140 毫秒
71.
Pure-Culture Growth of Fermentative Bacteria, Facilitated by H2 Removal: Bioenergetics and H2 Production
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We used an H2-purging culture vessel to replace an H2-consuming syntrophic partner, allowing the growth of pure cultures of Syntrophothermus lipocalidus on butyrate and Aminobacterium colombiense on alanine. By decoupling the syntrophic association, it was possible to manipulate and monitor the single organism's growth environment and determine the change in Gibbs free energy yield (ΔG) in response to changes in the concentrations of reactants and products, the purging rate, and the temperature. In each of these situations, H2 production changed such that ΔG remained nearly constant for each organism (−11.1 ± 1.4 kJ mol butyrate−1 for S. lipocalidus and −58.2 ± 1.0 kJ mol alanine−1 for A. colombiense). The cellular maintenance energy, determined from the ΔG value and the hydrogen production rate at the point where the cell number was constant, was 4.6 × 10−13 kJ cell−1 day−1 for S. lipocalidus at 55°C and 6.2 × 10−13 kJ cell−1 day−1 for A. colombiense at 37°C. S. lipocalidus, in particular, seems adapted to thrive under conditions of low energy availability. 相似文献
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Donna J. Schlemm Maria J. Crowe Redmond B. McNeill Anne E. Stanley Stephen J. Keller 《Cell stress & chaperones》1999,4(3):171-176
Alcoholic extracts of bakers' yeast (Saccharomyces cerevisiae) have been used for over 60 years in over-the-counter medications for the treatment of hemorrhoids, burns, and wounds. Although previous studies suggested that small peptides were responsible for the medical observations, the peptides were never resolved into separate fractions and identified. In the present report, a protein fraction was prepared by RPC18 chromatography of the extract which enhances wound closure in both diabetic and non-diabetic littermates. The peptides are active in nanomolar amounts and are 600 times more active than the initial extract. SDS-PAGE and N-terminal amino acid sequencing identified 4 polypeptides in the extract. Three of the proteins were small molecular weight stress-associated proteins: copper, zinc superoxide-dismutase, ubiquitin, and glucose lipid regulated protein (HSP 12). The fourth protein, acyl-CoA binding protein II, has not been previously associated with stress proteins. 相似文献
75.
Mary Redmond Hutson Faustina N. Sackey Katherine Lunney Margaret L. Kirby 《Developmental biology》2009,335(2):367-373
Cardiac neural crest cells (CNCC) migrate into the caudal pharynx and arterial pole of the heart to form the outflow septum. Ablation of the CNCC results in arterial pole malalignment and failure of outflow septation, resulting in a common trunk overriding the right ventricle. Unlike preotic cranial crest, the postotic CNCC do not normally regenerate. We applied the hedgehog signaling inhibitor, cyclopamine (Cyc), to chick embryos after CNCC ablation and found normal heart development at day 9 suggesting that the CNCC population was reconstituted. We ablated the CNCC, and labeled the remaining neural tube with DiI/CSRE and applied cyclopamine. Cells migrated from the neural tube in the CNCC-ablated, cyclopamine-treated embryos but not in untreated CNCC-ablated embryos. The newly generated cells followed the CNCC migration pathways, expressed neural crest markers and supported normal heart development. Finally, we tested whether reducing hedgehog signaling caused redeployment of the dorsal–ventral axis of the injured neural tube, allowing generation of new neural crest-like cells. The dorsal neural tube marker, Pax7, was maintained 12 h after CNCC ablation with Cyc treatment but not in the CNCC-ablated alone. This disruption of dorsal–ventral neural patterning permits a new wave of migratory cardiac neural crest-like cells. 相似文献
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Yan-Fung Wong Qing Sheng Janet WL Chung Jacky KF Chan King L Chow 《BMC developmental biology》2010,10(1):82
Background
C. elegans TGF-β-like Sma/Mab signaling pathway regulates both body size and sensory ray patterning. Most of the components in this pathway were initially identified by genetic screens based on the small body phenotype, and many of these mutants display sensory ray patterning defect. At the cellular level, little is known about how and where these components work although ray structural cell has been implicated as one of the targets. Based on the specific ray patterning abnormality, we aim to identify by RNAi approach additional components that function specifically in the ray lineage to elucidate the regulatory role of TGF-β signaling in ray differentiation. 相似文献79.
Heterophils, the avian polymorphonuclear leukocyte and the counterpart of mammalian neutrophils, generate the primary innate
response to pathogens in chickens. Heterophil performance against pathogens is associated with host disease resistance, and
heterophil gene expression and function are under genetic control. To characterize the genomic basis of heterophil function,
heterophils from F13 advanced intercross chicken lines (broiler × Leghorn and broiler × Fayoumi) were assayed for phagocytosis and killing of
Salmonella enteritidis, oxidative burst, and extracellular trap production. A whole-genome association analysis of single nucleotide polymorphisms
at 57,636 loci identified genomic locations controlling these functional phenotypes. Genomic analysis revealed a significant
association of extracellular trap production with the SAL1 locus and the SLC11A1 gene, which have both been previously associated with resistance to S. enteritidis. Fine mapping supports SIVA1 as a candidate gene controlling SAL1-mediated resistance and indicates that the proposed cell-death mechanism associated with extracellular trap production, ETosis,
likely functions through the CD27/Siva-1-mediated apoptotic pathway. The SLC11A1 gene was also associated with phagocytosis of S. enteritidis, suggesting that the Slc11a1 protein may play an additional role in immune response beyond depleting metal ions to inhibit
intracellular bacterial growth. A region of chromosome 6 with no characterized genes was also associated with extracellular
trap production. Further characterization of these novel genes in chickens and other species is needed to understand their
role in polymorphonuclear leukocyte function and host resistance to disease. 相似文献
80.
Yanwen Jiang David Redmond Kui Nie Ken W Eng Thomas Clozel Peter Martin Leonard HC Tan Ari M Melnick Wayne Tam Olivier Elemento 《Genome biology》2014,15(8)