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151.
Streptococcus pneumoniae is an important human pathogen associated with pneumonia, septicaemia, meningitis and otitis media. It is estimated to result in over 3 million child deaths worldwide every year and an even greater number of deaths among the elderly. Prior to the complete sequencing of the genomes of S. pneumoniae TIGR4 (serotype 4) and S. pneumoniae R6 (serotype 2), we designed a custom miniarray consisting of 497 pneumococcal genes. The overall objectives of our microarray investigations were, first, to assess the genetic diversity between different S. pneumoniae serotypes, clinical isolates and also different Streptococcus species; second, we aimed to use microarray technology to examine the mechanisms by which environmental factors influence pneumococcal gene expression, and ultimately to further the understanding of how these changes in gene expression are achieved and how they may alter the virulence of the organism. 相似文献
152.
RNA-Binding Activity of the E1B 55-Kilodalton Protein from Human Adenovirus Type 5 总被引:1,自引:1,他引:0 下载免费PDF全文
The human adenovirus 5 E1B 55-kDa protein is required for efficient nucleocytoplasmic transport of late viral mRNAs. This protein is shown to have RNA-binding activity which maps to a region of the protein with homology to a family of RNA-binding proteins and which has been shown previously to be essential for functionality of the protein in vivo. 相似文献
153.
Jackie D. Corbin Alfreda Beasley Illarion V. Turko Tamara L. Haik Kimberly A. Mangum Jack N. Wells Sharron H. Francis Konjeti R. Sekhar 《Cell biochemistry and biophysics》1998,29(1-2):145-157
The cGMP-binding cGMP-specific phosphodiesterase (PDE-5) contains distinct catalytic and allosteric binding sites, and each
is cGMP-specific. Cyclic nucleotide phosphodiesterase inhibitors, such as 3-isobutyl-1-methylxanthine (IBMX), are believed
to compete with cyclic nucleotides at the catalytic sites of these enzymes, but the portion of PDE-5 that accounts for interaction
of either of these inhibitors or the substrates themselves with the catalytic domain of the enzymes has not been identified.
IBMX was derivatized to yield the photoaffinity probe 8([3-125I,-4-azido]-benzyl)-IBMX, which is referred to as 8(125IAB)-IBMX. This probe was incubated with partially purified recombinant bovine PDE-5. After UV irradiation and SDS-PAGE, a
single radiolabeled band that coincided with the position of PDE-5 was visualized on the gel, and the photoaffinity labeling
of PDE-5 was linear with increasing concentration of the 8(125IAB)-IBMX. Prominent Coomassie blue-stained bands other than PDE-5 were not labeled significantly. The photo-affinity labeling
was progressively blocked by cGMP at concentrations higher than 10 μM, whereas cAMP or 5′-GMP exhibited only weak inhibitory effects. Other compounds that are believed to interact with the PDE-5
catalytic site, including IBMX, clMP, and β-phenyl-1,N
2-etheno-cGMP (PET-cGMP), also inhibited the photoaffinity labeling in a concentration-dependent manner. The IC50 of PET-cGMP for inhibition of photoaffinity labeling was 10 μM, which compared favorably with an IC50 of 5 μM for inhibition of PDE-5 catalytic activity by this compound. It is concluded that the interaction of this photoaffinity probe
with PDE-5 is highly specific for the catalytic site over the allosteric binding sites of PDE-5 and could prove useful in
studies to map the catalytic site of PDE-5. 相似文献
154.
Smith Jeffrey A. Francis Sharron H. Corbin Jackie D. 《Molecular and cellular biochemistry》1993,127(1):51-70
Most protein kinases catalyze autophosphorylation, a process which is generally intramolecular and is modulated by regulatory ligands. Either serine/threonine or tyrosine serves as the phosphoacceptor, and several sites on the same kinase subunit are usually autophosphorylated. Autophosphorylation affects the functional properties of most protein kinases. Members of the protein kinase family exhibit diversity in the characteristics and functions of autophosphorylation, but certain common themes are emerging. 相似文献
155.
Identifying the presence of bovine tuberculosis (TB; Mycobacterium bovis) in wildlife is crucial in guiding management aimed at eradicating the disease from New Zealand. Unfortunately, surveys of the principal wildlife host, the introduced brushtail possum (Trichosurus vulpecula), require large samples (> 95% of the population) before they can provide reasonable confidence that the disease is absent. In this study, we tested the feasibility of using a more wide-ranging species, feral pig (Sus scrofa), as an alternative sentinel capable of indicating TB presence. In January 2000, 17 pigs in four groups were released into a forested area with a low density of possums in which TB was known to be present. The pigs were radiotracked at 2 wk intervals from February to October 2000, and some of them were killed and necropsied at various intervals after release. Of the 15 pigs successfully recovered and necropsied, one killed 2 mo after release had no gross lesions typical of TB, and the only other pig killed at that time had greatly enlarged mandibular lymph nodes. The remainder were killed at longer intervals after release and all had gross lesions typical of TB. Mycobacterium bovis was isolated from all 15 pigs by mycobacterial culture. Home range sizes of pigs varied widely and increased with the length of time the pigs were in the forest, with minimum convex polygon range-size estimates averaging 10.7 km2 (range 4.7-20.3 km2) for the pigs killed after 6 mo. A 6 km radius around the kill site of each pig would have encompassed 95% of all of their previous locations at which they could have become infected. However, one pig shifted 35 km, highlighting the main limitation of using unmarked feral pigs as sentinels. This trial indicates use of resident and/or released free-ranging pigs is a feasible alternative to direct prevalence surveys of possums for detecting TB presence. 相似文献
156.
157.
Guanjun Shen Véronique Michel Jackie Despriée Fei Han Darryl E. Granger 《L'Anthropologie》2012,116(1):1-11
The radionuclides 26Al and 10Be in situ produced in quartz near the ground surface by secondary cosmic rays can be used for dating the sediment burial. This paper introduces the principles, preconditions and limitations of the recently established dating method. In China its first trial application is to the site of Peking man. The weighted mean of six significant results of samples from layers 7–10 is 770 ± 80 ka. This date provides strong support to an earlier and longer human presence at the site than once estimated. This method has also been applied for the first time to two Lower Paleolithic sites in the Cher Valley, central France, Lunery “la Terre-des-Sablons” and Brinay “la Noira”. The preliminary results attribute ages of 750 ± 240 and 730 ± 210 ka to the two sites, largely consistent with the previous age estimates based on geological and geomorphological studies and on ESR dating. With its well-founded basis in physics, its independence from other dating methods and its timescale filling a “blank period” in radioisotopic dating, the 26Al/10Be burial dating will be widely applied and contribute substantially to the establishment of a reliable timescale for the earliest human occurrence and evolution in China and in Europe. 相似文献
158.
159.
Shi YC Lin S Castillo L Aljanova A Enriquez RF Nguyen AD Baldock PA Zhang L Bijker MS Macia L Yulyaningsih E Zhang H Lau J Sainsbury A Herzog H 《Obesity (Silver Spring, Md.)》2011,19(11):2137-2148
Y2 receptors, particularly those in the brain, have been implicated in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone mass. Recent evidence also indicates a role for Y2 receptors in peripheral tissues in this process by promoting adipose tissue accretion; however their effects on energy balance remain unclear. Here, we show that adult-onset conditional knockdown of Y2 receptors predominantly in peripheral tissues results in protection against diet-induced obesity accompanied by significantly reduced weight gain, marked reduction in adiposity and improvements in glucose tolerance without any adverse effect on lean mass or bone. These changes occur in association with significant increases in energy expenditure, respiratory exchange ratio, and physical activity and despite concurrent hyperphagia. On a chow diet, knockdown of peripheral Y2 receptors results in increased respiratory exchange ratio and physical activity with no effect on lean or bone mass, but decreases energy expenditure without effecting body weight or food intake. These results suggest that peripheral Y2 receptor signaling is critical in the regulation of oxidative fuel selection and physical activity and protects against the diet-induced obesity. The lack of effects on bone mass seen in this model further indicates that bone mass is primarily controlled by non-peripheral Y2 receptors. This study provides evidence that novel drugs that target peripheral rather than central Y2 receptors could provide benefits for the treatment of obesity and glucose intolerance without adverse effects on lean and bone mass, with the additional benefit of avoiding side effects often associated with pharmaceuticals that act on the central nervous system. 相似文献
160.