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961.
At the age of three weeks the experimental animals received either thyrotropin (TSH), or gonadotropin (FSH + LH), or endotoxin (LPS) alone or in combination. The effectivity of the treatments was evaluated at the age of two months (with or without further hormone treatment). Contrastingly to neonatal TSH treatment, TSH treatment at the age of three weeks did not give rise to imprinting. In female animals, however, TSH treatment increased the sensitivity to the related gonadotropin hormone. At the age of three weeks gonadotropin treatment--on its own--did not cause damages to the TSH receptors of the thyroid gland. While in previous experiments neonatal endotoxin treatment damaged considerably the thyroxin production of the adult thyroid gland, after treatments at the age of three weeks no similar effect could be observed. The treatment, however, decreased the sensitivity of the receptors to TSH. In female animals simultaneous administration of endotoxin and TSH led, even without further hormone treatment, to constant increase in T4 level (the increase could also be detected in the adult animal). Imprinting, however, did not develop. In male animals simultaneous administration of endotoxin and gonadotroph hormone decreased considerably the T4 baseline level, and further TSH or gonadotropin treatment was unable to enhance T4 production. 相似文献
962.
We consider the problem of multicasting data to mobile users in a cellular mobile network. In the absence of mobility, a single
channel can be used to multicast to all mobile users within a cell. However, mobility combined with the effects of fading
necessitates a more complex channel allocation policy. In this paper we develop theoretical bounds on the maximum obtainable
efficiency and present algorithms that acheive this bound. Our results hold for the case when mobiles travel on a highway,
as well as for the more general case where mobiles roam in a two-dimensional region.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
963.
Total body water (TBW) volumes determined from the dilution space of injected tritiated water have consistently overestimated actual water volumes (determined by desiccation to constant mass) in reptiles and mammals, but results for birds are controversial. We investigated potential errors in both the dilution method and the desiccation method in an attempt to resolve this controversy. Tritiated water dilution yielded an accurate measurement of water mass in vitro. However, in vivo, this method yielded a 4.6% overestimate of the amount of water (3.1% of live body mass) in chukar partridges, apparently largely because of loss of tritium from body water to sites of dissociable hydrogens on body solids. An additional source of overestimation (approximately 2% of body mass) was loss of tritium to the solids in blood samples during distillation of blood to obtain pure water for tritium analysis. Measuring tritium activity in plasma samples avoided this problem but required measurement of, and correction for, the dry matter content in plasma. Desiccation to constant mass by lyophilization or oven-drying also overestimated the amount of water actually in the bodies of chukar partridges by 1.4% of body mass, because these values included water adsorbed onto the outside of feathers. When desiccating defeathered carcasses, oven-drying at 70 degrees C yielded TBW values identical to those obtained from lyophilization, but TBW was overestimated (0.5% of body mass) by drying at 100 degrees C due to loss of organic substances as well as water.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
964.
H Strzelecka-Golaszewska B Nagy J Gergely 《Archives of biochemistry and biophysics》1974,161(2):559-569
The ultraviolet difference spectra of EDTA-induced denaturation of dithiothreitoltreated actin prepared with either Ca2+, Mn2+, or Mg2+ as the strongly bound cation showed no appreciable difference, nor could any difference be found in the change of optical rotation. However, at different wavelengths the changes in the spectra have different rates and these rates do differ significantly depending on the bivalent cation bound to G-actin. The nucleotide and the cation appear to be removed simultaneously and at the fastest rate; about 50–80% is released within 1 min. The spectral changes have two phases: a fast change whose detailed kinetics have not been investigated in this paper, followed by a slower rate with first-order kinetics. The changes of optical rotation follow a single-phase first-order kinetics. The rates depend on the divalent cation, the sequence being Mn2+ > Ca2+ > Mg2+. ATP release is partially reversible upon Ca2+ addition; the reversibility is diminished as the time of incubation with EDTA is increased. On rebinding of ATP and Ca2+, the spectral and optical rotatory changes are not reversed, but no further changes occur. Such an EDTA-treated actin is polymerizable after addition of Ca2+, and the G-actin obtained after polymerization and depolymerization shows the same spectral change on a second addition of EDTA as the original actin. On the basis of these observations a scheme is suggested for the denaturation of G-actin. 相似文献
965.
Antibacterial Action of Essential Oils of Artemisia as an Ecological Factor: I. Antibacterial Action of the Volatile Oils of Artemisia tridentata and Artemisia nova on Aerobic Bacteria 总被引:2,自引:2,他引:0
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Bacterial response to increasing amounts of the volatile oils varies significantly according to species of bacteria tested. Among the four species examined, Escherichia coli was the most resistant to the oils, followed by Neisseria sicca, Bacillus subtilis, and Staphylococcus aureus. The oils of Artemisia tridentata seem to have the same degree of antibacterial action as oils obtained from A. nova. 相似文献
966.
967.
968.
Ryan M. Pace P. Cole Eskridge Miodrag Grbić Lisa M. Nagy 《Development genes and evolution》2014,224(4-6):209-222
Metazoans are known to contain a limited, yet highly conserved, set of signal transduction pathways that instruct early developmental patterning mechanisms. Genomic surveys that have compared gene conservation in signal transduction pathways between various insects and Drosophila support the conclusion that these pathways are conserved in evolution. However, the degree to which individual components of signal transduction pathways vary among more divergent arthropods is not known. Here, we report our results of a survey of the genome of the two-spotted spider mite Tetranychus urticae, using a set of 294 Drosophila orthologs of genes that function in signal transduction. We find a third of all genes surveyed absent from the spider mite genome. We also identify several novel duplications that have not been previously reported for a chelicerate. In comparison with previous insect surveys, Tetranychus contains a decrease in overall gene conservation, as well as an unusual ratio of ligands to receptors and other modifiers. These findings suggest that gene loss and duplication among components of signal transduction pathways are common among arthropods and suggest that signal transduction pathways in arthropods are more evolutionarily labile than previously hypothesized. 相似文献
969.
970.
Darryl Falzarano Emmie de Wit Friederike Feldmann Angela L. Rasmussen Atsushi Okumura Xinxia Peng Matthew J. Thomas Neeltje van Doremalen Elaine Haddock Lee Nagy Rachel LaCasse Tingting Liu Jiang Zhu Jason S. McLellan Dana P. Scott Michael G. Katze Heinz Feldmann Vincent J. Munster 《PLoS pathogens》2014,10(8)