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21.
In an isolated population of Drosophila melanogaster on Ishigaki Island the
chromosomal distribution of several retrotransposons, including copia, 412,
297, 17.6, I, and jockey elements, was examined by in situ hybridization.
In this population the cosmopolitan inversion, In(2L)t, is known to exist
in high frequency. One major haplotype concerning the occupied sites of the
transposable elements was identified in the In(2L)t-carrying chromosomes.
This haplotype is suggested to be the ancestral one. The age of the
inversion in this local population was estimated to be 1,400 generations.
The transposition rates of these elements were estimated based on the age
of the inversion and the number of the elements lost and gained. The
excision rates were in the range from 9.13 x 10(-5) to 2.25 x 10(-4) per
site per generation. They were similar each other in the copia-like
elements as well as in the LINE-like elements. The rate was higher in the
copia-like elements than in the LINE-like elements. Insertions occurred in
the range from 6.79 x 10(-4) to 9.05 x 10(-4) per element per generation.
It is herein shown that both insertions and excisions occurred at a
significantly higher rate in this population than in the laboratory.
相似文献
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Endogenous chloride channels of insect sf9 cells. Evidence for coordinated activity of small elementary channel units 总被引:1,自引:0,他引:1 下载免费PDF全文
EH Larsen SE Gabriei MJ Stutts J Fullton EM Price RC Boucher 《The Journal of general physiology》1996,107(6):695-714
The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.12 < f < 300 Hz, the power density spectrum of whole-cell Cl- currents could be fitted by three Lorentzians. Independent of membrane potential, >50% of the total variance of whole-cell current fluctuations was accounted for by the low frequency Lorentzian (fc = 0.40 +/- 0.03 Hz, n = 6). Single-Cl- channels showed complex gating kinetics with long lasting (seconds) openings interrupted by similar long closures. In the open state, channels exhibited fast burst-like closures. Since the patches normally contained more than a single channel, it was not possible to measure open and closed dwell-time distributions for comparing single-Cl- channel activity with the kinetic features of whole-cell currents. However, the power density spectrum of Cl- currents of cell-attached and excised outside-out patches contained both high and low frequency Lorentzian components, with the corner frequency of the slow component (fc = 0.40 +/- 0.02 Hz, n = 4) similar to that of whole-cell current fluctuations. Chloride channels exhibited multiple conductance states with similar Goldman-Hodgkin-Katz-type rectification. Single-channel permeabilities covered the range from approximately 0.6.10(-14) cm5/s to approximately 6.10(-14) cm3/s, corresponding to a limiting conductance (gamma 150/150) of approximately 3.5 pS and approximately 35 pS, respectively. All states reversed near the same membrane potential, and they exhibited similar halide ion selectivity, P1 > PCl approximately PBr. Accordingly, Cl- current amplitudes larger than current flow through the smallest channel unit resolved seem to result from simultaneous open/shut events of two or more channel units. 相似文献
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Yuker Wang Victoria EH Carlton George Karlin-Neumann Ronald Sapolsky Li Zhang Martin Moorhead Zhigang C Wang Andrea L Richardson Robert Warren Axel Walther Melissa Bondy Aysegul Sahin Ralf Krahe Musaffe Tuna Patricia A Thompson Paul T Spellman Joe W Gray Gordon B Mills Malek Faham 《BMC medical genomics》2009,2(1):1-13
Background
Novel tuberculosis (TB) vaccines recently tested in humans have been designed to boost immunity induced by the current vaccine, Mycobacterium bovis Bacille Calmette-Guérin (BCG). Because BCG vaccination is used extensively in infants, this population group is likely to be the first in which efficacy trials of new vaccines will be conducted. However, our understanding of the complexity of immunity to BCG in infants is inadequate, making interpretation of vaccine-induced immune responses difficult.Methods
To better understand BCG-induced immunity, we performed gene expression profiling in five 10-week old infants routinely vaccinated with BCG at birth. RNA was extracted from 12 hour BCG-stimulated or purified protein derivative of tuberculin (PPD)-stimulated PBMC, isolated from neonatal blood collected 10 weeks after vaccination. RNA was hybridised to the Sentrix® HumanRef-8 Expression BeadChip (Illumina) to measure expression of >16,000 genes.Results
We found that ex vivo stimulation of PBMC with PPD and BCG induced largely similar gene expression profiles, except that BCG induced greater macrophage activation. The peroxisome proliferator-activated receptor (PPAR) signaling pathway, including PPAR-γ, involved in activation of the alternative, anti-inflammatory macrophage response was down-regulated following stimulation with both antigens. In contrast, up-regulation of genes associated with the classic, pro-inflammatory macrophage response was noted. Further analysis revealed a decrease in the expression of cell adhesion molecules (CAMs), including integrin alpha M (ITGAM), which is known to be important for entry of mycobacteria into the macrophage. Interestingly, more leukocyte genes were down-regulated than up-regulated.Conclusion
Our results suggest that a combination of suppressed and up-regulated genes may be key in determining development of protective immunity to TB induced by vaccination with BCG. 相似文献24.
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Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns. 相似文献
28.
Van Dat Nguyen Feras Hatahet Kirsi EH Salo Eveliina Enlund Chi Zhang Lloyd W Ruddock 《Microbial cell factories》2011,10(1):1
Background
Disulfide bonds are one of the most common post-translational modifications found in proteins. The production of proteins that contain native disulfide bonds is challenging, especially on a large scale. Either the protein needs to be targeted to the endoplasmic reticulum in eukaryotes or to the prokaryotic periplasm. These compartments that are specialised for disulfide bond formation have an active catalyst for their formation, along with catalysts for isomerization to the native state. We have recently shown that it is possible to produce large amounts of prokaryotic disulfide bond containing proteins in the cytoplasm of wild-type bacteria such as E. coli by the introduction of catalysts for both of these processes. 相似文献29.
Shou Zhou Kevin D. Rynearson Kejia Ding Nicholas D. Brunn Thomas Hermann 《Bioorganic & medicinal chemistry》2013,21(20):6139-6144
The highly conserved internal ribosome entry site (IRES) of hepatitis C virus (HCV) regulates translation of the viral RNA genome and is essential for the expression of HCV proteins in infected host cells. The structured subdomain IIa of the IRES element is the target site of recently discovered benzimidazole inhibitors that selectively block viral translation through capture of an extended conformation of an RNA internal loop. Here, we describe the development of a FRET-based screening assay for similarly acting HCV translation inhibitors. The assay relies on monitoring fluorescence changes that indicate rearrangement of the RNA target conformation upon ligand binding. Screening of a small pilot set of potential RNA binders identified a benzoxazole scaffold as a ligand that bound selectively to IIa IRES target and was confirmed as an inhibitor of in vitro viral translation. The screening approach outlined here provides an efficient method to discover HCV translation inhibitors that may provide leads for the development of novel antiviral therapies directed at the highly conserved IRES RNA. 相似文献
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