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31.
The biosynthesis of the lipid-linked oligosaccharide substrate for N-
linked protein glycosylation follows a highly conserved pathway at the
membrane of the endoplasmic reticulum. Based on the synthetic growth defect
in combination with a reduced oligosaccharyltransferase activity (wbp1), we
have identified alg10 mutant strains which accumulate lipid- linked
Glc2Man9GlcNAc2. We cloned the corresponding wild-type gene and show in a
novel in vitro assay that Alg10p is a dolichyl-phosphoglucose- dependent
glucosyltransferase which adds the terminal alpha-1,2 glucose to the
lipid-linked Glc2Man9GlcNAc2 oligosaccharide. Hypoglycosylation of secreted
proteins in alg10 deletion strains demonstrates that the terminal
alpha-1,2-linked glucose residue is a key element in substrate recognition
by the oligosaccharyltransferase. This ensures that primarily completely
assembled oligosaccharide is transferred to protein.
相似文献
32.
33.
D J Burda 《Journal of morphology》1968,124(3):295-312
The development of intraneural vessels was studied in response to an induced hypermorphosis of neural tissue inthe midbrains of 38 chick embryos ranging in age from three days through 14 days of incubation. The pattern of vascularization was compared with that of normal chick embryos at comparable stages of development. In the experimental embryos, the increase in mitotic figures along the ventricular borders of the mesencephalon is accompanied by the establishment of an endoneural plexus approximately one day earlier than is the case during normal vascularization of the midbrain. This plexus also penetrates more deeply and extensively into the ependymal layer. Surface vessels and intraneural vascular elements are dilated, and the cerebrospinal fluid contains varying amounts of blood released from large intraneural vessels which protrude into the ventricle. The most prominent cerebrovascular effects seem to occur between the fourth and eighth days of incubation. Thereafter, the cerebrovascular pattern becomes more normal except for relatively few isolated hemorrhagic areas. 相似文献
34.
S. Credner H. Burda F. Ludescher 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(3):245-255
In captive adult Zambian mole-rats 14 different sounds (13 true vocalizations) have been recorded during different behavioural
contexts. The sound analysis revealed that all sounds occurred in a low and middle frequency range with main energy below
10 kHz. The majority of calls contained components of 1.6–2 kHz, 0.63–0.8 kHz, and/or 5–6.3 kHz. The vocalization range thus
matched well the hearing range as established in other studies. The frequency content of courtship calls in two species of
Zambian Cryptomys was compared with that in naked mole-rats (Heterocephalus glaber) and blind mole-rats (Spalax ehrenbergi) as described in the literature. The frequency range of maximum sound energy is negatively correlated with the body weight
and coincides with the frequencies of best hearing in the respective species. In general, the vocalization range in subterranean
mammals is shifted towards low frequencies which are best propagated in underground burrows.
Accepted: 16 September 1996 相似文献
35.
G. Brückmann H. Burda 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(1):83-88
Thresholds for pure tone detection were examined in the common mole-rat, Cryptomys sp. (Bathyergidae, Rodentia) using a positive reinforcement procedure. To bypass the problems connected with testing isolated
individuals of this extremely social species, a collective behavioural audiogram was determined for a family group of seven
mole-rats. Within the tested frequency range of 225 to 18 kHz, the lowest thresholds (as low as 7.5 dB SPL, on average 24
dB SPL) were found at 800 Hz, the upper limit of hearing (at the level of 60 dB SPL) was at 18 kHz. The behavioural audiogram
combines the results of previous studies on hearing in this species. It resembles the distortion threshold curve but differs
from neurophysiological data as far as the high frequency cutoff is concerned. On the other hand, the region of the best hearing
sensitivity is narrow in behavioural audiogram and neurophysiological curves but rather broad in the distortion threshold
curve. In general, the behavioural audiogram of Cryptomys is in many aspects comparable with the available audiograms of other subterranean rodents.
Accepted: 18 February 1997 相似文献
36.
Viera Danielisová Miroslav Gottlieb Miroslava Némethová Petra Kravčuková Iveta Domoráková Eva Mechírová Jozef Burda 《Cellular and molecular neurobiology》2009,29(6-7):871-878
Aims The present study was undertaken to evaluate possible neuroprotective effect of bradykinin against delayed neuronal death in hippocampal CA1 neurons if applied two days after transient forebrain ischemia in the rat. Methods Transient forebrain ischemia was induced in male Wistar rats by four-vessel occlusion for 8 min. To assess efficacy of bradykinin as a new stressor for delayed postconditioning we used two experimental groups of animals: ischemia 8 min and 3 days of survival, and ischemia 8 min and 3 days of survival with i.p. injection of bradykinin (150 μg/kg) applied 48 h after ischemia. Results We found extensive neuronal degeneration in the CA1 region at day 3 after ischemia/reperfusion. The postischemic neurodegeneration was preceded by increased activity of mitochondrial enzyme MnSOD in cytoplasm, indicating release of MnSOD from mitochondria in the process of delayed neuronal death. Increased cytosolic cytochrome c and subsequently caspase-3 activation are additional signs of neuronal death via the mitochondrial pathway. Bradykinin administration significantly attenuated ischemia-induced neuronal death, and also suppressed the release of MnSOD, and cytochrome c, and prevented caspase-3 activation. Conclusions Bradykinin can be used as an effective stressor able to prevent mitochondrial failure leading to apoptosis-like delayed neuronal death in postischemic rat hippocampus. 相似文献
37.
The effects of a selective inducible nitric oxide synthase inhibitor aminoguanidine (AG) on neuronal cells survival in hippocampal
CA1 region after middle cerebral artery occlusion (MCAO) were examined. Transient focal cerebral ischemia was induced in rats
by 60 or 90 min of MCAO, followed by 7 days of reperfusion. AG treatment (150 mg/kg i.p.) significantly reduced total infarct
volumes: by 70% after 90 min MCAO and by 95% after 60 min MCAO, compared with saline-treated ischemic group. The number of
degenerating neurons in hippocampal CA1 region was also markedly lower in aminoguanidine-treated ischemic groups compared
to ischemic groups without AG-treatment. The number of iNOS-positive cells significantly increased in the hippocampal CA1
region of ischemic animals, whereas it was reduced in AG-treated rats. Our findings demonstrate that aminoguanidine decreases
ischemic brain damage and improves neurological recovery after transient focal ischemia induced by MCAO. 相似文献
38.
39.
Serotyping of primary human immunodeficiency virus type 1 isolates from diverse geographic locations by flow cytometry. 总被引:8,自引:7,他引:1
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S Zolla-Pazner J O'Leary S Burda M K Gorny M Kim J Mascola F McCutchan 《Journal of virology》1995,69(6):3807-3815
The immunologic relatedness of the various human immunodeficiency virus type 1 (HIV-1) clades was determined with 13 human anti-HIV-1 monoclonal antibodies (MAbs) to six immunogenic regions of the HIV-1 structural proteins. The immunoreactivity of the native, oligomeric viral envelope glycoproteins expressed on the surfaces of human peripheral blood mononuclear cells infected in vitro with primary isolates from clades A through E was determined by flow cytometry. Some epitopes in the immunodominant region of gp41 and the C terminus of gp120 appear to be HIV-1 group specific in that they are expressed on the surfaces of cells in cultures infected with the majority of viruses tested from clades A to E. Epitopes within the V3 region appear to be clade restricted. Surprisingly, one MAb to an epitope in the C terminus of gp120 was entirely clade B specific. Staining with anti-V2 and anti-CD4 binding domain (CD4bd) reagents was infrequently detected. Anti-CD4bd MAbs stained only CD4-negative T cells because the CD4bd of gp120 appeared to be complexed with membrane CD4. When present, the epitopes of V2 and the CD4bd appeared to be expressed on cells infected with various clades. Thus, the results suggest that MAbs to gp41, the C terminus, and the V3 loop of gp120 are most useful in serotyping primary isolates of HIV-1, providing group-specific, clade-restricted, and clade-specific reagents. The use of the immunofluorescent method with the reagents described herein distinguishes infection with clade B from that with all other HIV-1 clades. With additional MAbs, this technique will allow a broadly applicable, reproducible, and practical method for serotyping HIV-1. 相似文献
40.