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61.
Alexander Jason B. Bunce Michael White Nicole Wilkinson Shaun P. Adam Arne A. S. Berry Tina Stat Michael Thomas Luke Newman Stephen J. Dugal Laurence Richards Zoe T. 《Coral reefs (Online)》2020,39(1):159-171
Coral Reefs - Cumulative anthropogenic pressures have triggered a global decline in the health of marine ecosystems, and coral reefs, in particular, are in crisis. With climate and... 相似文献
62.
Tina Paradzik Nives Ivic Zelimira Filic Babu A. Manjasetty Paul Herron Marija Luic Dusica Vujaklija 《Nucleic acids research》2013,41(6):3659-3672
The linear chromosome of Streptomyces coelicolor contains two paralogous ssb genes, ssbA and ssbB. Following mutational analysis, we concluded that ssbA is essential, whereas ssbB plays a key role in chromosome segregation during sporulation. In the ssbB mutant, ∼30% of spores lacked DNA. The two ssb genes were expressed differently; in minimal medium, gene expression was prolonged for both genes and significantly upregulated for ssbB. The ssbA gene is transcribed as part of a polycistronic mRNA from two initiation sites, 163 bp and 75 bp upstream of the rpsF translational start codon. The ssbB gene is transcribed as a monocistronic mRNA, from an unusual promoter region, 73 bp upstream of the AUG codon. Distinctive DNA-binding affinities of single-stranded DNA-binding proteins monitored by tryptophan fluorescent quenching and electrophoretic mobility shift were observed. The crystal structure of SsbB at 1.7 Å resolution revealed a common OB-fold, lack of the clamp-like structure conserved in SsbA and previously unpublished S-S bridges between the A/B and C/D subunits. This is the first report of the determination of paralogous single-stranded DNA-binding protein structures from the same organism. Phylogenetic analysis revealed frequent duplication of ssb genes in Actinobacteria, whereas their strong retention suggests that they are involved in important cellular functions. 相似文献
63.
64.
Mircea Winter Mirjam A Moser Dominique Meunier Katharina Mattes Christina Murko Christina Humer Tina Meischel Gerald Brosch Patrick Matthias Maria Sibilia Christian Seiser 《The EMBO journal》2013,32(24):3176-3191
The histone deacetylases HDAC1 and HDAC2 remove acetyl moieties from lysine residues of histones and other proteins and are important regulators of gene expression. By deleting different combinations of Hdac1 and Hdac2 alleles in the epidermis, we reveal a dosage‐dependent effect of HDAC1/HDAC2 activity on epidermal proliferation and differentiation. Conditional ablation of either HDAC1 or HDAC2 in the epidermis leads to no obvious phenotype due to compensation by the upregulated paralogue. Strikingly, deletion of a single Hdac2 allele in HDAC1 knockout mice results in severe epidermal defects, including alopecia, hyperkeratosis, hyperproliferation and spontaneous tumour formation. These mice display impaired Sin3A co‐repressor complex function, increased levels of c‐Myc protein, p53 expression and apoptosis in hair follicles (HFs) and misregulation of HF bulge stem cells. Surprisingly, ablation of HDAC1 but not HDAC2 in a skin tumour model leads to accelerated tumour development. Our data reveal a crucial function of HDAC1/HDAC2 in the control of lineage specificity and a novel role of HDAC1 as a tumour suppressor in the epidermis. 相似文献
65.
Dimitry N. Krementsov Tina M. Thornton Cory Teuscher Mercedes Rincon 《Molecular and cellular biology》2013,33(19):3728-3734
Multiple sclerosis (MS), the most common disabling neurologic disease of young adults, is considered a classical T cell-mediated disease and is characterized by demyelination, axonal damage, and progressive neurological dysfunction. The currently available disease-modifying therapies are limited in their efficacy, and improved understanding of new pathways contributing to disease pathogenesis could reveal additional novel therapeutic targets. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is known to be triggered by stress stimuli and to contribute to inflammatory responses. Importantly, a number of recent studies have identified this signaling pathway as a central player in MS and its principal animal model, experimental allergic encephalomyelitis. Here, we review the evidence from mouse and human studies supporting the role of p38 MAPK in regulating key immunopathogenic mechanisms underlying autoimmune inflammatory disease of the central nervous system and the potential of targeting this pathway as a disease-modifying therapy in MS. 相似文献
66.
P. Charukeshi Chandrasekera Tina C. Wan Elizabeth T. Gizewski John A. Auchampach Robert D. Lasley 《Cellular signalling》2013,25(4):736-742
G protein coupled receptors play crucial roles in mediating cellular responses to external stimuli, and increasing evidence suggests that they function as multiple units comprising homo/heterodimers and hetero-oligomers. Adenosine and β-adrenergic receptors are co-expressed in numerous tissues and mediate important cellular responses to the autocoid adenosine and sympathetic stimulation, respectively. The present study was undertaken to examine whether adenosine A1ARs heterodimerize with β1- and/or β2-adrenergic receptors (β1R and β2R), and whether such interactions lead to functional consequences. Co-immunoprecipitation and co-localization studies with differentially epitope-tagged A1, β1, and β2 receptors transiently co-expressed in HEK-293 cells indicate that A1AR forms constitutive heterodimers with both β1R and β2R. This heterodimerization significantly influenced orthosteric ligand binding affinity of both β1R and β2R without altering ligand binding properties of A1AR. Receptor-mediated ERK1/2 phosphorylation significantly increased in cells expressing A1AR/β1R and A1AR/β2R heteromers. β-Receptor-mediated cAMP production was not altered in A1AR/β1R expressing cells, but was significantly reduced in the A1AR/β2R cells. The inhibitory effect of the A1AR on cAMP production was abrogated in both A1AR/β1R and A1AR/β2R expressing cells in response to the A1AR agonist CCPA. Co-immunoprecipitation studies conducted with human heart tissue lysates indicate that endogenous A1AR, β1R, and β2R also form heterodimers. Taken together, our data suggest that heterodimerization between A1 and β receptors leads to altered receptor pharmacology, functional coupling, and intracellular signaling pathways. Unique and differential receptor cross-talk between these two important receptor families may offer the opportunity to fine-tune crucial signaling responses and development of more specific therapeutic interventions. 相似文献
67.
Summary The occurrence of vitellogenin in adult haploid drones of the honeybee, Apis mellifica, was determined by sensitive immunotechniques, i.e. two-dimensional Immunoelectrophoresis and SDS-PAGE immunoblotting using a monospecific anti-vitellogenin-serum. In drones vitellogenin is one of the minor fractions of the hemolymph proteins. Genetic and regulatory aspects of vitellogenin synthesis in male bees are discussed. 相似文献
68.
This before-and-after-impact study uses the natural abundance N isotope ratio (δ15N) to investigate the effects of a wildfire on sub-alpine ecosystem properties and processes. We measured the 15N signatures of soil, charred organic material, ash and foliage in three sub-alpine plant communities (grassland, heathland and woodland) in south-eastern Australia. Surface bulk soil was temporarily enriched in 15N immediately after wildfire compared to charred organic material and ash in all plant communities. We associated the enrichment of bulk soil with fractionation of N during combustion and volatilization of N, a process that also explains the sequential enrichment of 15N of unburnt leaves > ash > charred organic material in relation to duration and intensity of heating. The rapid decline in 15N of bulk soil to pre-fire values indicates that depleted ash, containing considerable amounts of total N, was readily incorporated into the soil. Foliar δ15N also increased with values peaking 1 year post-fire. Foliar enrichment was foremost coupled with the release of enriched NH4 + into the soil owing to isotopic discrimination during volatilization of soluble N and combustion of organic material. The mode of post-fire regeneration influenced foliar 15N enrichment in two species indicating use of different sources of N following fire. The use of natural abundance of 15N in soil, ash and foliage as a means of tracing transformation of N during wildfire has established the importance of combustion products as an important, albeit temporary source of inorganic N for plants regenerating after wildfire. 相似文献
69.
Jaemyeong Jung Anurag Sethi Tiziano Gaiotto Jason J. Han Tina Jeoh Sandrasegaram Gnanakaran Peter M. Goodwin 《The Journal of biological chemistry》2013,288(33):24164-24172
The efficient catalytic conversion of biomass to bioenergy would meet a large portion of energy requirements in the near future. A crucial step in this process is the enzyme-catalyzed hydrolysis of cellulose to glucose that is then converted into fuel such as ethanol by fermentation. Here we use single-molecule fluorescence imaging to directly monitor the movement of individual Cel7A cellobiohydrolases from Trichoderma reesei (TrCel7A) on the surface of insoluble cellulose fibrils to elucidate molecular level details of cellulase activity. The motion of multiple, individual TrCel7A cellobiohydrolases was simultaneously recorded with ∼15-nm spatial resolution. Time-resolved localization microscopy provides insights on the activity of TrCel7A on cellulose and informs on nonproductive binding and diffusion. We measured single-molecule residency time distributions of TrCel7A bound to cellulose both in the presence of and absence of cellobiose the major product and a potent inhibitor of Cel7A activity. Combining these results with a kinetic model of TrCel7A binding provides microscopic insight into interactions between TrCel7A and the cellulose substrate. 相似文献
70.
Ho Seong Seo George Minasov Ravin Seepersaud Kelly S. Doran Ievgeniia Dubrovska Ludmilla Shuvalova Wayne F. Anderson Tina M. Iverson Paul M. Sullam 《The Journal of biological chemistry》2013,288(50):35982-35996
The serine-rich repeat glycoproteins of Gram-positive bacteria comprise a large family of cell wall proteins. Streptococcus agalactiae (group B streptococcus, GBS) expresses either Srr1 or Srr2 on its surface, depending on the strain. Srr1 has recently been shown to bind fibrinogen, and this interaction contributes to the pathogenesis of GBS meningitis. Although strains expressing Srr2 appear to be hypervirulent, no ligand for this adhesin has been described. We now demonstrate that Srr2 also binds human fibrinogen and that this interaction promotes GBS attachment to endothelial cells. Recombinant Srr1 and Srr2 bound fibrinogen in vitro, with affinities of KD = 2.1 × 10−5 and 3.7 × 10−6
m, respectively, as measured by surface plasmon resonance spectroscopy. The binding site for Srr1 and Srr2 was localized to tandem repeats 6–8 of the fibrinogen Aα chain. The structures of both the Srr1 and Srr2 binding regions were determined and, in combination with mutagenesis studies, suggest that both Srr1 and Srr2 interact with a segment of these repeats via a “dock, lock, and latch” mechanism. Moreover, properties of the latch region may account for the increased affinity between Srr2 and fibrinogen. Together, these studies identify how greater affinity of Srr2 for fibrinogen may contribute to the increased virulence associated with Srr2-expressing strains. 相似文献