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81.
82.
Background
The YjgF/YER057c/UK114 family of proteins is widespread in nature, but has as yet no clearly defined biological role. Members of the family exist as homotrimers and are characterised by intersubunit clefts that are delineated by well-conserved residues; these sites are likely to be of functional significance, yet catalytic activity has never been detected for any member of this family. The gene encoding the TdcF protein of E. coli, a YjgF/YER057c/UK114 family member, resides in an operon that strongly suggests a role in the metabolism of 2-ketobutyrate for this protein. 相似文献83.
Ank de Jonge Jeanette A. J. M. Mesman Judith Manni?n Joost J. Zwart Simone E. Buitendijk Jos van Roosmalen Jeroen van Dillen 《PloS one》2015,10(5)
ObjectiveTo test the hypothesis that it is possible to select a group of low risk women who can start labour in midwife-led care without having increased rates of severe adverse maternal outcomes compared to women who start labour in secondary care.ResultsNulliparous and parous women who started labour in midwife-led care had lower rates of SAMM, postpartum haemorrhage and manual removal of placenta compared to women who started labour in secondary care. For SAMM the adjusted odds ratio’s and 95% confidence intervals were for nulliparous women: 0.57 (0.45 to 0.71) and for parous women 0.47 (0.36 to 0.62).ConclusionsOur results suggest that it is possible to identify a group of women at low risk of obstetric complications who may benefit from midwife-led care. Women can be reassured that we found no evidence that midwife-led care at the onset of labour is unsafe for women in a maternity care system with a well developed risk selection and referral system. 相似文献
84.
Changqing Liu Rob A. Schmitz Arjan Pol Carmen Hogendoorn Daniël Verhagen Stijn H. Peeters Theo A. van Alen Geert Cremers Rob A. Mesman Huub J. M. Op den Camp 《Environmental microbiology》2024,26(3):e16602
Terrestrial geothermal ecosystems are hostile habitats, characterized by large emissions of environmentally relevant gases such as CO2, CH4, H2S and H2. These conditions provide a niche for chemolithoautotrophic microorganisms. Methanotrophs of the phylum Verrucomicrobia, which inhabit these ecosystems, can utilize these gases and grow at pH levels below 1 and temperatures up to 65°C. In contrast, methanotrophs of the phylum Proteobacteria are primarily found in various moderate environments. Previously, novel verrucomicrobial methanotrophs were detected and isolated from the geothermal soil of the Favara Grande on the island of Pantelleria, Italy. The detection of pmoA genes, specific for verrucomicrobial and proteobacterial methanotrophs in this environment, and the partially overlapping pH and temperature growth ranges of these isolates suggest that these distinct phylogenetic groups could coexist in the environment. In this report, we present the isolation and characterization of a thermophilic and acid-tolerant gammaproteobacterial methanotroph (family Methylococcaceae) from the Favara Grande. This isolate grows at pH values ranging from 3.5 to 7.0 and temperatures from 35°C to 55°C, and diazotrophic growth was demonstrated. Its genome contains genes encoding particulate and soluble methane monooxygenases, XoxF- and MxaFI-type methanol dehydrogenases, and all enzymes of the Calvin cycle. For this novel genus and species, we propose the name ‘Candidatus Methylocalor cossyra’ CH1. 相似文献
85.
Molecular phylogenetic evidence that the phylum Haplosporidia has an alveolate ancestry 总被引:1,自引:0,他引:1
The phylogenetic position of the phylum Haplosporidia among other protists
was investigated with the complete 16S-like rRNA gene sequences from two
species in the phylum: Haplosporidium nelsoni, a parasite of oysters, and
Minchinia teredinis, a parasite of shipworms. Because the lack of obvious
morphological homologies with other protists hampered decisions regarding
taxonomic composition for sequence alignment and phylogenetic analysis, the
complete sequences for these two haplosporidians were directed as search
queries to the blast/ncbi.nlm.nih.gov electronic mail server. The results
of this heuristic similarity search provided a basis for constructing a
preliminary higher-taxonomic-level analysis comparing the haplosporidians
with species from the slime molds, fungi, algae, amoebae, ciliates,
dinoflagellates, and apicomplexans. Maximum parsimony yielded equivocal
results, whereas transversionally weighted parsimony suggested an affinity
with the alveolates (i.e., the ciliates, dinoflagellates, and
apicomplexans). Multiple alignment of the two haplosporidian sequences
against 17 taxa in a secondary analysis focusing on the alveolates and
subsequent parsimony analysis placed the phylum Haplosporidia as a
monophyletic group within the Alveolata and as a taxon of equal rank with
the other three alveolate phyla. The precise placement within the Alveolata
was sensitive to weighting.
相似文献
86.
In limulus sperm an actin filament bundle 55 mum in length extends from the acrosomal vacuole membrane through a canal in the nucleus and then coils in a regular fashion around the base of the nucleus. The bundle expands systematically from 15 filaments near the acrosomal vacuole to 85 filaments at the basal end. Thin sections of sperm fixed during stages in spermatid maturation reveal that the filament bundle begins to assemble on dense material attached to the acrosomal vacuole membrane. In micrographs fo these early stages in maturation, short bundles are seen extending posteriorly from the dense material. The significance is that these short, developing bundles have about 85 filaments, suggesting that the 85-filament end of the bundle is assembled first. By using filament bundles isolated and incubated in vitro with G actin from muscle, we can determine the end “preferred” for addition of actin monomers during polymerization. The end that would be associated with the acrosomal vacuole membrane, a membrane destined to be continuous with the plasma membrane, is preferred about 10 times over the other, thicker end. Decoration of the newly polymerized portions of the filament bundle with subfragment 1 of myosin reveals that the arrowheads point away from the acrosomal vacuole membrane, as is true of other actin filament bundles attached to membranes. From these observations we conclude that the bundle is nucleated from the dense material associated with the acrosomal vacuole and that monomers are added to the membrane-associated end. As monomers are added at the dense material, the thick first-made end of the filament bundle is pushed down through the nucleus where, upon reaching the base of the nucleus, it coils up. Tapering is brought about by the capping of the peripheral filaments in the bundle. 相似文献
87.
Conservation of alternative splicing and genomic organization of the myosin alkali light-chain (Mlc1) gene among Drosophila species 总被引:3,自引:0,他引:3
The Mlc1 gene of Drosophila melanogaster encodes two MLC1 isoforms via
developmentally regulated alternative pre-mRNA splicing. In larval muscle
and tubular and abdominal muscles of adults, all of the six exons are
included in the spliced mRNA, whereas, in the fibrillar indirect flight
muscle of adult, exon 5 is excluded from the mRNA. We show that this
tissue-specific pattern of alternative splicing of the Mlc1 pre-mRNA is
conserved in D. simulans, D. pseudoobscura, and D. virilis. Isolation and
sequencing of the Mlc1 genes from these three other Drosophila species have
revealed that the overall organization of the genes is identical and that
the genes have maintained a very high level of sequence identity within the
coding region. Pairwise amino acid identities are 94%-99%, and there are no
charge changes among the proteins. Total nucleotide divergence within the
coding region of the four genes supports the accepted genealogy of these
species, but the data indicate a significantly higher rate of amino acid
replacement in the branch leading to D. pseudoobscura. A comparison of
nucleotide substitutions in the coding portions of exon 5 and exon 6, which
encode the alternative carboxyl termini of the two MLC1 isoforms, suggests
that exon 5 is subject to greater evolutionary constraints than is exon 6.
In addition to the coding sequences, there is significant sequence
conservation within the 5' and 3' noncoding DNA and two of the introns,
including one that flanks exon 5. These regions are candidates for cis-
regulatory elements. Our results suggest that evolutionary constraints are
acting on both the coding and noncoding sequences of the Mlc1 gene to
maintain proper expression and function of the two MLC1 polypeptides.
相似文献
88.
89.
90.
Nabbe KC van Lent PL Holthuysen AE Sloëtjes AW Koch AE Radstake TR van den Berg WB 《Arthritis research & therapy》2005,7(2):R392-R401
During immune-complex-mediated arthritis (ICA), severe cartilage destruction is mediated by Fcγ receptors (FcγRs) (mainly
FcγRI), cytokines (e.g. IL-1), and enzymes (matrix metalloproteinases (MMPs)). IL-13, a T helper 2 (Th2) cytokine abundantly
found in synovial fluid of patients with rheumatoid arthritis, has been shown to reduce joint inflammation and bone destruction
during experimental arthritis. However, the effect on severe cartilage destruction has not been studied in detail. We have
now investigated the role of IL-13 in chondrocyte death and MMP-mediated cartilage damage during ICA. IL-13 was locally overexpressed
in knee joints after injection of an adenovirus encoding IL-13 (AxCAhIL-13), 1 day before the onset of arthritis; injection
of AxCANI (an empty adenoviral construct) was used as a control. IL-13 significantly increased the amount of inflammatory
cells in the synovial lining and the joint cavity, by 30% to 60% at day 3 after the onset of ICA. Despite the enhanced inflammatory
response, chondrocyte death was diminished by two-thirds at days 3 and 7. The mRNA level of FcγRI, a receptor shown to be
crucial in the induction of chondrocyte death, was significantly down-regulated in synovium. Furthermore, MMP-mediated cartilage
damage, measured as neoepitope (VDIPEN) expression using immunolocalization, was halved. In contrast, mRNA levels of MMP-3,
-9, -12, and -13 were significantly higher and IL-1 protein, which induces production of latent MMPs, was increased fivefold
by IL-13. This study demonstrates that IL-13 overexpression during ICA diminished both chondrocyte death and MMP-mediated
VDIPEN expression, even though joint inflammation was enhanced. 相似文献