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11.
12.
Cecilia PC Soh Alastair SR Donald James Feeney Walter TJ Morgan Winifred M Watkins 《Glycoconjugate journal》1989,6(3):319-332
The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and1H-500 MHz NMR spectroscopy. In Sda serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity. 相似文献
13.
Concentrations of viruses and prokaryotes in the alkaline, moderately hypersaline, seasonally stratified Mono Lake are among
the highest reported for a natural aquatic environment. We used electron microscopy to test whether viral morphological characteristics
differed among the epilimnion, metalimnion, and the anoxic hypolimnion of the lake and to determine how the properties of
viruses in Mono Lake compare to other aquatic environments. Viral capsid size distributions were more similar in the metalimnion
and hypolimnion of Mono Lake, while viral tail lengths were more similar in the epilimnion and metalimnion. The percentage
of tailed viruses decreased with depth and the relative percentages of tailed phage families changed with depth. The presence
of large (>125 nm capsid), untailed viruses in the metalimnion and hypolimnion suggests that eukaryotic viruses are produced
in these suboxic and anoxic, hypersaline environments. Capsid diameters of viruses were larger on average in Mono Lake compared
to other aquatic environments, and no lemon-shaped or filamentous viruses were found, in contrast to other high-salinity or
high-altitude lakes and seas. Our data suggest that the physically and chemically distinct layers of Mono Lake harbor different
viral assemblages, and that these assemblages are distinct from other aquatic environments that have been studied. Furthermore,
we found that filtration of a sample through a 0.22-μm pore-size filter significantly altered the distribution of viral capsid
diameters and tail lengths, resulting in a relative depletion of viruses having larger capsids and longer tails. This observation
highlights the potential for bias in molecular surveys of viral diversity, which typically rely on filtration through 0.2-
or 0.22-μm pore-size membrane filters to remove bacteria during sample preparation. 相似文献
14.
Structural relatedness of lysis proteins from colicinogenic plasmids and icosahedral coliphages 总被引:4,自引:0,他引:4
The host-lysis-inducing functions of phi X174 protein E and MS2 protein L
were recently shown to reside on the N-terminal and C-terminal halves of
the two respective lysis proteins. In the present study it is shown that
the small lysis proteins encoded in various colicinogenic plasmids share
local sequence similarities and certain structural characteristics with the
essential peptides of their coliphage-coded counterparts. Despite their
dissimilar sizes and origins, it is suggested that the colicinogenic lysis
proteins are functionally analogous and evolutionarily related to those of
icosahedral single- stranded DNA and RNA phages.
相似文献
15.
16.
Colmenero-Flores JM Martínez G Gamba G Vázquez N Iglesias DJ Brumós J Talón M 《The Plant journal : for cell and molecular biology》2007,50(2):278-292
Chloride (Cl(-)) is an essential nutrient and one of the most abundant inorganic anions in plant tissues. We have cloned an Arabidopsis thaliana cDNA encoding for a member of the cation-Cl(-) cotransporter (CCC) family. Deduced plant CCC proteins are highly conserved, and phylogenetic analyses revealed their relationships to the sub-family of animal K(+):Cl(-) cotransporters. In Xenopus laevis oocytes, the A. thaliana CCC protein (At CCC) catalysed the co-ordinated symport of K(+), Na(+) and Cl(-), and this transport activity was inhibited by the 'loop' diuretic bumetanide, a specific inhibitor of vertebrate Na(+):K(+):Cl(-) cotransporters, indicating that At CCC encodes for a bona fide Na(+):K(+):Cl(-) cotransporter. Analysis of At CCC promoter-beta-glucuronidase transgenic Arabidopsis plants revealed preferential expression in the root and shoot vasculature at the xylem/symplast boundary, root tips, trichomes, leaf hydathodes, leaf stipules and anthers. Plants homozygous for two independent T-DNA insertions in the CCC gene exhibited shorter organs such as inflorescence stems, roots, leaves and siliques. The elongation zone of the inflorescence stem of ccc plants often necrosed during bolt emergence, while seed production was strongly impaired. In addition, ccc plants exhibited defective Cl(-) homeostasis under high salinity, as they accumulated higher and lower Cl(-) amounts in shoots and roots, respectively, than the treated wild type, suggesting At CCC involvement in long-distance Cl(-) transport. Compelling evidence is provided on the occurrence of cation-chloride cotransporters in the plant kingdom and their significant role in major plant developmental processes and Cl(-) homeostasis. 相似文献
17.
Pereira P Vinadé E Rodrigues L De David e Silva TL Ardenghi P da Silva Brum LF Gonçalves CA Izquierdo I 《Neurochemical research》2007,32(7):1150-1155
The participation of protein serine/threonine kinases in memory formation and retrieval is well established. In contrast,
relatively little is known on the role of protein tyrosine kinases (PTKs). Previous work showed that intra-hippocampal infusion
of the Src-PTK inhibitor radicicol inhibits memory acquisition, consolidation, and retrieval of one-trial step-down inhibitory avoidance
task. In this study, we investigated the possible interaction between levels of Src-PTK activity in hippocampus and memory acquisition, formation, and retrieval of this task. Radicicol (0.5 μg/ml) was infused
into the CA1 region of the hippocampus of rats trained in a one-trial step-down inhibitory avoidance task. Radicicol infused
15 min before training decreased Src-PTK activity, as measured 0, 1.5, and 24 h after training, and impaired memory acquisition of the task. When given immediately
after training, there was a decrease in Src-PTK activity 1.5 h, but not 0 or 24 h after training. This treatment depressed memory consolidation. Radicicol infused into
CA1 10 min prior to retrieval testing inhibited hippocampal Src-PTK activity, as measured immediately after the test session. The results suggest that Src-PTKs participate in memory acquisition, consolidation, and retrieval processes, but the timing of the role of the enzyme
is different in each case. 相似文献
18.
V.R. CoelhoJ. Gianesini R. Von BorowskiL. Mazzardo-Martins D.F. MartinsJ.N. Picada A.R.S. SantosL.F.S. Brum P. Pereira 《Phytomedicine》2011,18(10):896-901
It is known that (−)-linalool is a competitive antagonist of NMDA receptors, which play a key role in the learning and memory processes; however, only a few studies have reported a possible interference of (−)-linalool in memory. The purpose of this study was to investigate the (−)-linalool effects on acquisition of short- and long-term memories through the objects recognition task, inhibitory avoidance test and habituation to a novel environment. Furthermore, the open field test was used to investigate the interference of (−)-linalool in motivation, locomotion and exploration by animals. Wistar male adult rats received an intraperitoneal injection (i.p.) of saline (NaCl 0.9%), tween 5% or (−)-linalool (50 or 100 mg/kg) before training in the tasks; MK-801 (0.1 mg/kg), a glutamate antagonist, was used as positive control. Short-term (STM) and long-term (LTM) memories were tested 1.5 and 24 h after training, respectively, in the inhibitory avoidance and recognition objects. The results suggested that (−)-linalool (as 50- and 100-mg/kg doses) impaired LTM acquisition, but not STM acquisition, in the object recognition task. In the inhibitory avoidance test, animals receiving linalool (both doses) showed impairment in acquisition of both memories measured. In the open field test, the animals that received (−)-linalool showed no significant difference in the crossings and latency to start the locomotion in any of the doses tested, although (−)-linalool 100 mg/kg reduced rearing behavior. When re-exposed to open field 24 h after training, the rats that received (−)-linalool 100 mg/kg showed no habituation. Taken together, these data suggested that (−)-linalool was able to impair the acquisition of memory in rats, which can be associated to (−)-linalool antagonist capacity as regards NMDA glutamatergic receptors, since other glutamate antagonists also seem to affect memory. 相似文献
19.
Carl PC Chen Chih-Chin Hsu Wen-Lin Yeh Hsiu-Chu Lin Sen-Yung Hsieh Shih-Cherng Lin Tai-Tzung Chen Max JL Chen Simon FT Tang 《Proteome science》2011,9(1):1-10
Background
Prenatal screening for Down Syndrome (DS) would benefit from an increased number of biomarkers to improve sensitivity and specificity. Improving sensitivity and specificity would decrease the need for potentially risky invasive diagnostic procedures.Results
We have performed an in depth two-dimensional difference gel electrophoresis (2D DIGE) study to identify potential biomarkers. We have used maternal plasma samples obtained from first and second trimesters from mothers carrying DS affected fetuses compared with mothers carrying normal fetuses. Plasma samples were albumin/IgG depleted and expanded pH ranges of pH 4.5 - 5.5, pH 5.3 - 6.5 and pH 6 - 9 were used for two-dimensional gel electrophoresis (2DE). We found no differentially expressed proteins in the first trimester between the two groups. Significant up-regulation of ceruloplasmin, inter-alpha-trypsin inhibitor heavy chain H4, complement proteins C1s subcomponent, C4-A, C5, and C9 and kininogen 1 were detected in the second trimester in maternal plasma samples where a DS affected fetus was being carried. However, ceruloplasmin could not be confirmed as being consistently up-regulated in DS affected pregnancies by Western blotting.Conclusions
Despite the in depth 2DE approach used in this study the results underline the deficiencies of gel-based proteomics for detection of plasma biomarkers. Gel-free approaches may be more productive to increase the number of plasma biomarkers for DS for non-invasive prenatal screening and diagnosis. 相似文献20.
de Armas Rodríguez Y Wissmann G Müller AL Pederiva MA Brum MC Brackmann RL Capó de Paz V Calderón EJ 《Parasite (Paris, France)》2011,18(3):219-228
Pneumocystis pneumonia (PcP) is a serious fungal infection among immunocompromised patients. In developed countries, the epidemiology and clinical spectrum of PcP have been clearly defined and well documented. However, in most developing countries, relatively little is known about the prevalence of pneumocystosis. Several articles covering African, Asian and American countries were reviewed in the present study. PcP was identified as a frequent opportunistic infection in AIDS patients from different geographic regions. A trend to an increasing rate of PcP was apparent in developing countries from 2002 to 2010. 相似文献