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61.
62.
Kevin B. Hallberg Elena González-Toril D. Barrie Johnson 《Extremophiles : life under extreme conditions》2010,14(1):9-19
Phenotypic and genotypic analysis was carried out on four iron- and sulfur-oxidizing acidophilic bacteria (the “NO-37 group”)
isolated from different parts of the world. 16S rRNA phylogeny showed that they are highly related to each other, but are
less related to the type strain of Acidithiobacillus ferrooxidans. The NO-37 group isolates are obligate chemolithoautotrophs, facultative anaerobes, diazotrophic, and psychrotolerant. They
are less tolerant of extremely low pH, and in contrast to At. ferrooxidans
T, all of the NO-37 group isolates are motile. The GC contents of genomic DNA of the NO-37 group isolates were around 56 mol%
and the DNA–DNA hybridization value between genomic DNA of isolate NO-37 and At. ferrooxidans
T was 37%. It also appears that the bacteria of the NO-37 group have a different biochemical mechanism for oxidizing ferrous
iron than At. ferrooxidans
T; the gene coding for the archetypal rusticyanin (RusA) was not detected in any of the NO-37 group isolates, rather a gene
coding for a homologous protein (RusB) was amplified from three of the four novel isolates. Isolates of the NO-37 group clearly
belong to a species that is different to those already recognized in the genus Acidithiobacillus, for which the name Acidithiobacillus ferrivorans is proposed. 相似文献
63.
The LINC (linker of nucleoskeleton and cytoskeleton) complex forms a transcisternal bridge across the NE (nuclear envelope) that connects the cytoskeleton with the nuclear interior. This enables some proteins of the NE to communicate with the centrosome and the microtubule cytoskeleton. The position of the centrosome relative to the NE is of vital importance for many cell functions, such as cell migration and division, and centrosomal dislocation is a frequent phenotype in laminopathic disorders. Also in mitosis, a small group of transmembrane NE proteins associate with microtubules when they concentrate in a specific membrane domain associated with the mitotic spindle. The present review discusses structural and functional aspects of microtubule association with NE proteins and how this association may be maintained over the cell cycle. 相似文献
64.
Ancestral gene fusion in cellobiose dehydrogenases reflects a specific evolution of GMC oxidoreductases in fungi 总被引:1,自引:0,他引:1
Cellobiose dehydrogenases (CDHs) are extracellular hemoflavoenzymes that are thought to be involved in the degradation of two of the most abundant biopolymers in the biosphere, cellulose and lignin. To date, these enzymes, consisting of a cytochrome domain and a flavin domain, have been detected and sequenced exclusively in the kingdom of fungi. Independent phylogenetic analyses of two distinct domains of CDH genes reveal that they evolved in parallel as fused genes. Whereas the cytochrome domains are unique sequence motifs, the flavin domains clearly belong to the glucose-methanol-choline (GMC) oxidoreductase family--an evolution line of widespread flavoproteins extending from the Archae to higher eukaryotes. The most probable unrooted phylogenetic tree obtained from our analysis of 52 selected GMC members reveals five principal evolutionary branches: cellobiose dehydrogenase, cholesterol oxidase (COX), hydroxynitrile lyase, alcohol oxidase (AOX)/glucose oxidase (GOX)/choline dehydrogenase, and a branch of dehydrogenases with various specificities containing also an Archaeon open reading frame (ORF). Cellobiose dehydrogenases cluster with cholesterol oxidases and the clade of various specificities, whereas hydroxynitrile lyases are closely related to glucose oxidases, alcohol oxidases, and choline dehydrogenases. The results indicate that the evolutionary line from a primordial GMC flavoprotein to extant cellobiose dehydrogenases was augmented after an early acquisition of the cytochrome domain to form two distinct branches for basidiomycetes and ascomycetes. One ascomycetous evolutionary line of CDHs has acquired a carbohydrate-binding module (CBM) of type 1, the sequence of which is similar to that of corresponding domains in several glycosidases. This is the first attempt towards a comprehensive phylogenetic analysis of cellobiose dehydrogenases. 相似文献
65.
Claudia A. McCarthy Antony Vinh Alyson A. Miller Anders Hallberg Mathias Alterman Jennifer K. Callaway Robert E. Widdop 《PloS one》2014,9(4)
Background
In this study, the neuroprotective effect of a novel nonpeptide AT2R agonist, C21, was examined in a conscious model of stroke to verify a class effect of AT2R agonists as neuroprotective agents.Methods and Results
Spontaneously hypertensive rats (SHR) were pre-treated for 5 days prior to stroke with C21 alone or in combination with the AT2R antagonist PD123319. In a separate series of experiments C21 was administered in a series of 4 doses commencing 6 hours after stroke. A focal reperfusion model of ischemia was induced in conscious SHR by administering endothelin-1 to the middle cerebral artery (MCA). Motor coordination was assessed at 1 and 3 days after stroke and post mortem analyses of infarct volumes, microglia activation and neuronal survival were performed at 72 hours post MCA occlusion. When given prior to stroke, C21 dose dependently decreased infarct volume, which is consistent with the behavioural findings illustrating an improvement in motor deficit. During the pre-treatment protocol C21 was shown to enhance microglia activation, which are likely to be evoking protection by releasing brain derived neurotrophic factor. When drug administration was delayed until 6 hours after stroke, C21 still reduced brain injury.Conclusion
These results indicate that centrally administered C21 confers neuroprotection against stroke damage. This benefit is likely to involve various mechanisms, including microglial activation of endogenous repair and enhanced cerebroperfusion. Thus, we have confirmed the neuroprotective effect of AT2R stimulation using a nonpeptide compound which highlights the clinical potential of the AT2R agonists for future development. 相似文献66.
picA, a novel plant-inducible locus on the Agrobacterium tumefaciens chromosome. 总被引:3,自引:2,他引:1
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L Rong S J Karcher K O''''Neal M C Hawes C D Yerkes R K Jayaswal C A Hallberg S B Gelvin 《Journal of bacteriology》1990,172(10):5828-5836
We used the transposon Mu dI1681 to identify genes on the Agrobacterium tumefaciens chromosome that are inducible by extracts from carrot roots. One such locus (picA, for plant inducible chromosomal), harbored by A. tumefaciens At156, was inducible 10- to 50-fold by these extracts. Mutation of picA had no detectable effect upon bacterial growth or virulence under laboratory assay conditions. However, A. tumefaciens cells harboring a mutated picA locus aggregated into long "ropes" when incubated with pea root tip cells. Such aggregation was not displayed by the parental strain A. tumefaciens A136. A preliminary characterization of the inducing compound in the carrot root extract suggests that the active substance is an acidic polysaccharide that is most likely derived from the pectic portion of the plant cell wall. 相似文献
67.
Induction of acquired thermotolerance in Tetrahymena thermophila: effects of protein synthesis inhibitors. 总被引:10,自引:5,他引:5
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When Tetrahymena thermophila cells growing at 30 degrees C are shifted to either 40 or 43 degrees C, the kinetics and extent of induction of heat shock mRNAs in both cases are virtually indistinguishable. However, the cells shifted to 40 degrees C show a typical induction of heat shock protein (HSP) synthesis and survive indefinitely (100% after 24 h), whereas those at 43 degrees C show an abortive synthesis of HSPs and die (less than 0.01% survivors) within 1 h. Cells treated at 30 degrees C with the drugs cycloheximide or emetine, at concentrations which are initially inhibitory to protein synthesis and cell growth but from which cells can eventually recover and resume growth, are after this recovery able to survive a direct shift from 30 to 43 degrees C (ca. 70% survival after 1 h). This induction of thermotolerance by these drugs is as efficient in providing thermoprotection to cells as is a prior sublethal heat treatment which elicits the synthesis of HSPs. However, during the period when drug-treated cells recover their protein synthesis ability and simultaneously acquire the ability to subsequently survive a shift to 43 degrees C, none of the major HSPs are synthesized. The ability to survive a 1-h, 43 degrees C heat treatment, therefore, does not absolutely require the prior synthesis of HSPs. But, as extended survival at 43 degrees Celsius depends absolutely on the ability of cells to continually synthesize HSPs, it appears that a prior heat shock as well as the recovery from protein synthesis inhibition elicits a change in the protein synthetic machinery which allows the translation of HSP mRNAs at what would otherwise be a nonpermissive temperature for protein synthesis. 相似文献
68.
A diamond drill core from the upper part of the Jeerinah Formation (~2.63 Ga), underlying the Hamersley Group, deposited at a time when the oxygen concentrations in the marine environment were extremely low, was examined for microbial fossils. The paper presents organo-mineral structures in the form of twisted stalks produced by bacteria being present in the laminated black carbonaceous shale sediments. These twisted stalks are organo-mineral structures produced by microaerophilic Fe(II)-oxidizing-type bacteria such as Gallionella and/or Mariprofundus that are active at very low-oxygen concentrations, thus providing evidence for oxygen being present in the marine environment at 2.63 Ga. 相似文献
69.
Optimization of sulphide production in an anaerobic continuous biofilm process with sulphate reducing bacteria 总被引:1,自引:0,他引:1
Different biofilm reactors for sulphide production by sulphate reducing bacteria were compared in a packed bed reactor and in two suspended carrier biofilm reactors. Lactate was used as carbon source in the experiments. The process was reversibly inhibited by free sulphide at 14 mM. The packed bed reactor was more efficient and less sensitive to changes. The maximum load in the system was 5.3 g sulphate/l.d. 相似文献
70.
Thomas GH; Newbern EC; Korte CC; Bales MA; Muse SV; Clark AG; Kiehart DP 《Molecular biology and evolution》1997,14(12):1285-1295
Many structural, signaling, and adhesion molecules contain tandemly
repeated amino acid motifs. The alpha-actinin/spectrin/dystrophin
superfamily of F-actin-crosslinking proteins contains an array of triple
alpha-helical motifs (spectrin repeats). We present here the complete
sequence of the novel beta-spectrin isoform beta(Heavy)- spectrin (beta H).
The sequence of beta H supports the origin of alpha- and beta-spectrins
from a common ancestor, and we present a novel model for the origin of the
spectrins from a homodimeric actin-crosslinking precursor. The pattern of
similarity between the spectrin repeat units indicates that they have
evolved by a series of nested, nonuniform duplications. Furthermore, the
spectrins and dystrophins clearly have common ancestry, yet the repeat unit
is of a different length in each family. Together, these observations
suggest a dynamic period of increase in repeat number accompanied by
homogenization within each array by concerted evolution. However, today,
there is greater similarity of homologous repeats between species than
there is across repeats within species, suggesting that concerted evolution
ceased some time before the arthropod/vertebrate split. We propose a
two-phase model for the evolution of the spectrin repeat arrays in which an
initial phase of concerted evolution is subsequently retarded as each new
protein becomes constrained to a specific length and the repeats diverge at
the DNA level. This evolutionary model has general applicability to the
origins of the many other proteins that have tandemly repeated motifs.
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