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101.
Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy 总被引:3,自引:0,他引:3
Transferrin, a glycoprotein involved in iron transport in body fluids, was
isolated from amniotic fluid of a hydramniospatient by sequential
anion-exchange chromatography and gel filtration. The N-glycans of human
amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F
digestion, isolated by gel filtration and fractionated by (high-pH)
anion-exchange chromatography. After alkaline borohydride treatment of
native hAFT, the released O-glycans were isolated by gel filtration and
fractionated by anion-exchange chroma-tography. Structure elucidation of 14
N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy.
Besides conventional N-glycans established earlier for human serum
transferrin (hST), new (alpha1-3)-fucosylated N- glycans were found,
representing sialyl Le(x) elements. Furthermore, as compared to hST, a
higher degree of (alpha1-6)-fucosylation and an increase in branching from
di- to triantennary compounds has been detected. The presence of O-glycans
is demonstrated for the first time in transferrin.
相似文献
102.
103.
Evolutionary transfer of ORF-containing group I introns between different subcellular compartments (chloroplast and mitochondrion) 总被引:10,自引:2,他引:8
Turmel M; Cote V; Otis C; Mercier JP; Gray MW; Lonergan KM; Lemieux C 《Molecular biology and evolution》1995,12(4):533-545
We describe here a case of homologous introns containing homologous open
reading frames (ORFs) that are inserted at the same site in the large
subunit (LSU) rRNA gene of different organelles in distantly related
organisms. We show that the chloroplast LSU rRNA gene of the green alga
Chlamydomonas pallidostigmatica contains a group I intron (CpLSU.2)
encoding a site-specific endonuclease (I-CpaI). This intron is inserted at
the identical site (corresponding to position 1931-1932 of the Escherichia
coli 23S rRNA sequence) as a group I intron (AcLSU.m1) in the mitochondrial
LSU rRNA gene of the amoeboid protozoon Acanthamoeba castellanii. The
CpLSU.2 intron displays a remarkable degree of nucleotide similarity in
both primary sequence and secondary structure to the AcLSU.m1 intron;
moreover, the Acanthamoeba intron contains an ORF in the same location
within its secondary structure as the CpLSU.2 ORF and shares with it a
strikingly high level of amino acid similarity (65%; 42% identity). A
comprehensive survey of intron distribution at site 1931 of the chloroplast
LSU rRNA gene reveals a rather restricted occurrence within the
polyphyletic genus Chlamydomonas, with no evidence of this intron among a
number of non- Chlamydomonad green algae surveyed, nor in land plants. A
parallel survey of homologues of a previously described and similar
intron/ORF pair (C. reinhardtii chloroplast CrLSU/A. castellanii
mitochondrial AcLSU.m3) also shows a restricted occurrence of this intron
(site 2593) among chloroplasts, although the intron distribution is
somewhat broader than that observed at site 1931, with site-2593 introns
appearing in several green algal branches outside of the Chlamydomonas
lineage. The available data, while not definitive, are most consistent with
a relatively recent horizontal transfer of both site-1931 and site- 2593
introns (and their contained ORFs) between the chloroplast of a
Chlamydomonas-type organism and the mitochondrion of an Acanthamoeba- like
organism, probably in the direction chloroplast to mitochondrion. The data
also suggest that both introns could have been acquired in a single event.
相似文献
104.
The robustness of two phylogenetic methods: four-taxon simulations reveal a slight superiority of maximum likelihood over neighbor joining 总被引:6,自引:3,他引:3
The robustness (sensitivity to violation of assumptions) of the maximum-
likelihood and neighbor-joining methods was examined using simulation.
Maximum likelihood and neighbor joining were implemented with Jukes-
Cantor, Kimura, and gamma models of DNA substitution. Simulations were
performed in which the assumptions of the methods were violated to varying
degrees on three model four-taxon trees. The performance of the methods was
evaluated with respect to ability to correctly estimate the unrooted
four-taxon tree. Maximum likelihood outperformed neighbor joining in 29 of
the 36 cases in which the assumptions of both methods were satisfied. In
133 of 180 of the simulations in which the assumptions of the
maximum-likelihood and neighbor-joining methods were violated, maximum
likelihood outperformed neighbor joining. These results are consistent with
a general superiority of maximum likelihood over neighbor joining under
comparable conditions. They extend and clarify an earlier study that found
an advantage for neighbor joining over maximum likelihood for
gamma-distributed mutation rates.
相似文献
105.
C Tardif H Maamar M Balfin JP Belaich 《Journal of industrial microbiology & biotechnology》2001,27(5):271-274
Electropermeabilization of Clostridium cellulolyticum was optimized using ATP leakage assays. Electrotransformation was then performed under optimized conditions (6 to 7.5 kV
cm−1 field strength applied during 5 ms to a mixture containing methylated plasmids and late exponential phase cell suspensions
(10 molecules:1 cell) in a sucrose-containing buffer). Transformants were only obtained when 7 or 7.5 kV cm−1 pulses were applied. Transformation efficiencies evaluated from the growth curves of transformed cells were between 105 and 107 transformants per microgram of plasmid DNA for five different replicon-based plasmids. Restriction nuclease digestion patterns
of pJIR418 purified from transformed Clostridia and Escherichia coli were indistinguishable, indicating that heterologous DNA was structurally stable in the Clostridium strain. Copy numbers of 130, 70 and 10 were estimated from purification yield for pCTC1, pKNT19 and pJIR418, respectively.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 271–274.
Received 12 September 2000/ Accepted in revised form 25 November 2000 相似文献
106.
Publication of the complete diploid genome sequence of the yeast Candida albicans will accelerate research into the pathogenesis of Candida infections. Comparative genomic analysis highlights genes that may contribute to C. albicans survival and its fitness as a human commensal and pathogen. 相似文献
107.
Koen JP Verhees Nicholas AM Pansters Hoeke A Baarsma Alexander HV Remels Astrid Haegens Chiel C de Theije Annemie MWJ Schols Reinoud Gosens Ramon CJ Langen 《Respiratory research》2013,14(1):117
Background
Chronic obstructive pulmonary disease (COPD) is accompanied by pulmonary inflammation and associated with extra-pulmonary manifestations, including skeletal muscle atrophy. Glycogen synthase kinase-3 (GSK-3) has been implicated in the regulation of muscle protein- and myonuclear turnover; two crucial processes that determine muscle mass. In the present study we investigated the effect of the selective GSK-3 inhibitor SB216763 on muscle mass in a guinea pig model of lipopolysaccharide (LPS)-induced pulmonary inflammation-associated muscle atrophy.Methods
Guinea pigs were pretreated with either intranasally instilled SB216763 or corresponding vehicle prior to each LPS/saline challenge twice weekly. Pulmonary inflammation was confirmed and indices of muscle mass were determined after 12 weeks. Additionally, cultured skeletal muscle cells were incubated with tumor necrosis factor α (TNF-α) or glucocorticoids (GCs) to model the systemic effects of pulmonary inflammation on myogenesis, in the presence or absence of GSK-3 inhibitors.Results
Repeated LPS instillation induced muscle atrophy based on muscle weight and muscle fiber cross sectional area. Intriguingly, GSK-3 inhibition using SB216763 prevented the LPS-induced muscle mass decreases and myofiber atrophy. Indices of protein turnover signaling were unaltered in guinea pig muscle. Interestingly, inhibition of myogenesis of cultured muscle cells by TNF-α or synthetic GCs was prevented by GSK-3 inhibitors.Conclusions
In a guinea pig model of LPS-induced pulmonary inflammation, GSK-3 inhibition prevents skeletal muscle atrophy without affecting pulmonary inflammation. Resistance to inflammation- or GC-induced impairment of myogenic differentiation, imposed by GSK-3 inhibition, suggests that sustained myogenesis may contribute to muscle mass maintenance despite persistent pulmonary inflammation. Collectively, these results warrant further exploration of GSK-3 as a potential novel drug target to prevent or reverse muscle wasting in COPD. 相似文献108.
J P Palavicini H Wang E Bianchi S Xu J S Rao D E Kang M K Lakshmana 《Cell death & disease》2013,4(6):e667
We previously demonstrated that overexpression of RanBP9 led to enhanced Aβ generation in a variety of cell lines and primary neuronal cultures, and subsequently, we confirmed increased amyloid plaque burden in a mouse model of Alzheimer''s disease (AD). In the present study, we found striking reduction of spinophilin protein levels when RanBP9 is overexpressed. At 12 months of age, we found spinophilin levels reduced by 70% (P<0.001) in the cortex of APΔE9/RanBP9 mice compared with that in wild-type (WT) controls. In the hippocampus, the spinophilin levels were reduced by 45% (P<0.01) in the APΔE9/RanBP9 mice. Spinophilin immunoreactivity was also reduced by 22% (P<0.01) and 12% (P<0.05) in the cortex of APΔE9/RanBP9 and APΔE9 mice, respectively. In the hippocampus, the reductions were 27% (P<0.001) and 14% (P<0.001) in the APΔE9/RanBP9 and APΔE9 mice, respectively. However, in the cerebellum, spinophilin levels were not altered in either APΔE9 or APΔE9/RanBP9 mice. Additionally, synaptosomal functional integrity was reduced under basal conditions by 39% (P<0.001) in the APΔE9/RanBP9 mice and ∼23% (P<0.001) in the APΔE9 mice compared with that in WT controls. Under ATP- and KCl-stimulated conditions, we observed higher mitochondrial activity in the WT and APΔE9 mice, but lower in the APΔE9/RanBP9 mice. Significantly, we confirmed the inverse relationship between RanBP9-N60 and spinophilin in the synaptosomes of Alzheimer''s brains. More importantly, both APΔE9 and APΔE9/RanBP9 mice showed impaired learning and memory skills compared to WT controls. These data suggest that RanBP9 might play a crucial role in the loss of spines and synapses in AD. 相似文献
109.
Alistair JP Brown 《Genome biology》2010,11(5):302
A report of the symposium on Signaling and Systems Biology held during the Society for General Microbiology Spring Meeting,
29-30 March 2010, Edinburgh, UK. 相似文献
110.