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11.
Recently, a group of diplomonads has been found to use a genetic code in
which TAA and TAG encode glutamine rather than termination. To survey the
distribution of this characteristic in diplomonads, we sought to identify
TAA and TAG codons at positions where glutamine is expected in genes for
alpha-tubulin, elongation factor-1 alpha, and the gamma subunit of
eukaryotic translation initiation factor-2. These sequences show that the
variant genetic code is utilized by almost all diplomonads, with the genus
Giardia alone using the universal genetic code. Comparative phylogenetic
analysis reveals that the switch to this genetic code took place very early
in the evolution of diplomonads and was likely a single event. Termination
signals and downstream untranslated regions were also cloned from three
Hexamita genes. In all three of these genes, the predicted TGA termination
codon was found at the expected position. Interestingly, the untranslated
regions of these genes are high in AT. This is incongruent with the coding
regions, which are comparatively GC-rich.
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12.
Jeroen CW Rijk Ad ACM Peijnenburg Peter JM Hendriksen Johan M Van Hende Maria J Groot Michel WF Nielen 《BMC veterinary research》2010,6(1):44
Background
Within the European Union the use of growth promoting agents in animal production is prohibited. Illegal use of natural prohormones like dehydroepiandrosterone (DHEA) is hard to prove since prohormones are strongly metabolized in vivo. In the present study, we investigated the feasibility of a novel effect-based approach for monitoring abuse of DHEA. Changes in gene expression profiles were studied in livers of bull calves treated orally (PO) or intramuscularly (IM) with 1000 mg DHEA versus two control groups, using bovine 44K DNA microarrays. In contrast to controlled genomics studies, this work involved bovines purchased at the local market on three different occasions with ages ranging from 6 to 14 months, thereby reflecting the real life inter-animal variability due to differences in age, individual physiology, season and diet. 相似文献13.
14.
Jonathan WF Mant Suzanne H Richards FD Richard Hobbs David Fitzmaurice Gregory YH Lip Ellen Murray Miriam Banting Kate Fletcher Joy Rahman Teresa Allan James Raftery Stirling Bryan 《BMC cardiovascular disorders》2003,3(1):1-10
Background
Statins effectively lower blood cholesterol and the risk of cardiovascular death. Immunomodulatory actions, independent of their lipid-lowering effect, have also been ascribed to these compounds. Since macrophages participate in several vascular pathologies, we examined the effect of statin treatment on the survival and differentiation of primary human monocytes.Methods
Peripheral blood mononuclear cells (PBMCs) from healthy individuals were cultured in the presence or absence of mevastatin. Apoptosis was monitored by annexin V / PI staining and flow cytometry. In parallel experiments, cultures were stimulated with LPS in the presence or absence of mevastatin and the release of IL-1β and IL-1Ra was measured by ELISA.Results
Among PBMCs, mevastatin-treated monocytes were particularly susceptible to apoptosis, which occurred at doses >1 microM and was already maximal at 5 microM. However, even at the highest mevastatin dose used (10 microM), apoptosis occurred only after 24 h of culture, possibly reflecting a requirement for cell commitment to differentiation. After 72 h of treatment the vast majority (>50%) of monocytes were undergoing apoptosis. Stimulation with LPS revealed that mevastatin-treated monocytes retained the high IL-1β output characteristic of undifferentiated cells; conversely, IL-1Ra release was inhibited. Concurrent treatment with mevalonolactone prevented the induction of apoptosis and suppressed both IL-1β and IL-1Ra release in response to LPS, suggesting a rate-limiting role for HMG-CoA reductase in monocyte differentiation.Conclusions
Our findings indicate that statins arrest the functional differentiation of monocytes into macrophages and steer these cells into apoptosis, suggesting a novel mechanism for the vasculoprotective properties of HMG-CoA reductase inhibitors. 相似文献15.
E?BaptesteEmail author E?Susko J?Leigh D?MacLeod RL?Charlebois WF?Doolittle 《BMC evolutionary biology》2005,5(1):33
Background
Since Darwin's Origin of Species, reconstructing the Tree of Life has been a goal of evolutionists, and tree-thinking has become a major concept of evolutionary biology. Practically, building the Tree of Life has proven to be tedious. Too few morphological characters are useful for conducting conclusive phylogenetic analyses at the highest taxonomic level. Consequently, molecular sequences (genes, proteins, and genomes) likely constitute the only useful characters for constructing a phylogeny of all life. For this reason, tree-makers expect a lot from gene comparisons. The simultaneous study of the largest number of molecular markers possible is sometimes considered to be one of the best solutions in reconstructing the genealogy of organisms. This conclusion is a direct consequence of tree-thinking: if gene inheritance conforms to a tree-like model of evolution, sampling more of these molecules will provide enough phylogenetic signal to build the Tree of Life. The selection of congruent markers is thus a fundamental step in simultaneous analysis of many genes. 相似文献16.
Ouabain-insensitive salt and water movements in duck red cells. II. The role of chloride in the volume response 下载免费PDF全文
This paper describes the effect of external chloride on the typical swelling response induced in duck red cells by hypertonicity or norepinephrine. Lowering chloride inhibits swelling and produces concomitant changes in net movements of sodium and potassium in ouabain-treated cells, which resemble the effect of lowering external sodium or potassium. Inhibition is the same whether chloride is replaced with gluconate or with an osmotic equivalent of sucrose. Since changes in external chloride also cause predictable changes in cell chloride, pH, and water, these variables were systematically investigated by varying external pH along with chloride. Lowering pH to 6.60 does not abolish the response if external chloride levels are normal, although the cells are initially swollen due to the increased acidity. Cells deliberately preswollen in hypotonic solutions with appropriate ionic composition can also respond to norepinephrine by further swelling. These results rule out initial values of cell water, chloride, and pH as significant variables affecting the response. Initial values of the chloride equilibrium potential do have marked effect on the direction and rate of net water movement. If chloride is lowered by replacement with the permeant anion, acetate, E(Cl) is unchanged and a normal response to norepinephrine, which is inhibited by furosemide, is observed. Increasing internal sodium by the nystatin technique also inhibits the response. A theory is developed which depicts that the cotransport carrier proposed in the previous paper (W.F. Schmidt and T.J. McManus. 1977b. J. Gen. Physiol. 70:81-97) moves in response to the net electrochemical potential difference driving sodium and potassium across the membrane. Predictions of this theory fit the data for both cations and anions. 相似文献
17.
18.
Restriction-map variation with the yellow-achaete-scute region in five populations of Drosophila melanogaster 总被引:9,自引:0,他引:9
It has been proposed that the degree of recombination for a genomic region
will affect the level of both nucleotide heterozygosity and the density of
transposable elements. Both features of genomic diversity have been
examined in a number of recent reports for regions undergoing relatively
normal levels of recombination in Drosophila melanogaster. In this study
the genomic variation associated with yellow-achaete- scute loci located at
the tip of the X chromosome is examined by six- cutter restriction mapping.
In this region, as usual for regions adjacent to telomeres, crossing-over
is dramatically reduced, and published studies of visible mutants indicate
extremely little restriction-map variation. Eight six-cutter restriction
endonucleases were used to locate sequence variation in 14- and 16.5-kb
regions in 109 lines sampled from North America, Africa, and Europe. The
overall level of heterozygosity is estimated as 0.29%. Nine large
insertions, all presumed to be transposable elements, were observed.
Base-pair heterozygosity appears to be reduced compared with regions having
normal levels of recombination. The estimated heterozygosity is much higher
than reported in earlier studies of restriction-map variation among visible
mutations in the complex. The incidence of large insertions is not elevated
compared with that in other regions of the genome. This suggests that
asymmetric synapsis and exchange is not an important mechanism for the
elimination of transposable elements.
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19.
Effects of context on judgements of odor intensities in humans 总被引:2,自引:2,他引:0
This study evaluated whether the intensity of previously smelled odors
could unintentionally influence the subsequent judgement of odor intensity.
The predicted context effect was based on the adaptation- level theory.
Before and 25 min after either WEAK or STRONG biasing odor concentrations,
51 subjects were required to rate the intensity of 10 different odor
concentrations of California Orange Oil. After the WEAK bias, subjects
judged the odor intensity as being stronger than they did after the STRONG
bias. Thus the intensity of odors smelled 25 min earlier can
unintentionally influence subsequent odor intensity judgement. The findings
are discussed in the light of two alternative explanations, namely, a
central implicit memory process and a stimulus- level-based change at the
peripheral level.
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20.
NICOLETTE W. M. van BUREN ADRIANA G. H. MARIËN ROB C. H. M. OUDEJANS HAYO H. W. VELTHUIS 《Physiological Entomology》1992,17(3):288-296
Abstract. The distribution of coumaphos (the active component of perizin), fed to individual honeybees, in the honey stomach, haemolymph, midgut and rectum was studied over time. Concurrently, we investigated changes occurring in the haemolymph volume due to the ingestion of perizin, and we examined the influence of a Nosema apis infection on the survival of bees that had been fed perizin. The maximum amount of coumaphos in the haemolymph was found 4h after ingestion, but it was only 2–3% of the total amount recovered. After 15 min 55% of the total amount of the coumaphos recovered was in the honey stomach and available for distribution within the colony by trophallaxis, while 45% had already passed the proventriculus. Ultimately the coumaphos accumulated in the rectum. The volume of the haemolymph significantly increased in bees which were fed perizin compared with bees which were fed syrup and with non-fed bees. The lethal dose of coumaphos to 3-day-old bees was three times higher than the lethal dose for 18- and 1-day-old bees. The number of Nosema apis spores in the alimentary canal was not correlated with the survival of the bees that were fed perizin. It is concluded that coumaphos can act as a systemic agent and can be distributed to other individuals in a colony through trophallaxis, but these effects are limited to a maximum period of 12h after ingestion. 相似文献