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1.
We have evaluated codon usage bias in Drosophila histone genes and have
obtained the nucleotide sequence of a 5,161-bp D. hydei histone gene repeat
unit. This repeat contains genes for all five histone proteins (H1, H2a,
H2b, H3, and H4) and differs from the previously reported one by a second
EcoRI site. These D. hydei repeats have been aligned to each other and to
the 5.0-kb (i.e., long) and 4.8-kb (i.e., short) histone repeat types from
D. melanogaster. In each species, base composition at synonymous sites is
similar to the average genomic composition and approaches that in the small
intergenic spacers of the histone gene repeats. Accumulation of synonymous
changes at synonymous sites after the species diverged is quite high. Both
of these features are consistent with the relatively low codon usage bias
observed in these genes when compared with other Drosophila genes. Thus,
the generalization that abundantly expressed genes in Drosophila have high
codon bias and low rates of silent substitution does not hold for the
histone genes.
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Joshua B. Slee Ivan S. Alferiev Robert J. Levy Stanley J. Stachelek 《Journal of visualized experiments : JoVE》2014,(90)
The foreign body reaction occurs when a synthetic surface is introduced to the body. It is characterized by adsorption of blood proteins and the subsequent attachment and activation of platelets, monocyte/macrophage adhesion, and inflammatory cell signaling events, leading to post-procedural complications. The Chandler Loop Apparatus is an experimental system that allows researchers to study the molecular and cellular interactions that occur when large volumes of blood are perfused over polymeric conduits. To that end, this apparatus has been used as an ex vivo model allowing the assessment of the anti-inflammatory properties of various polymer surface modifications. Our laboratory has shown that blood conduits, covalently modified via photoactivation chemistry with recombinant CD47, can confer biocompatibility to polymeric surfaces. Appending CD47 to polymeric surfaces could be an effective means to promote the efficacy of polymeric blood conduits. Herein is the methodology detailing the photoactivation chemistry used to append recombinant CD47 to clinically relevant polymeric blood conduits and the use of the Chandler Loop as an ex vivo experimental model to examine blood interactions with the CD47 modified and control conduits. 相似文献
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Choe JY Nelson SW Arienti KL Axe FU Collins TL Jones TK Kimmich RD Newman MJ Norvell K Ripka WC Romano SJ Short KM Slee DH Fromm HJ Honzatko RB 《The Journal of biological chemistry》2003,278(51):51176-51183
A highly constrained pseudo-tetrapeptide (OC252-324) further defines a new allosteric binding site located near the center of fructose-1,6-bisphosphatase. In a crystal structure, pairs of inhibitory molecules bind to opposite faces of the enzyme tetramer. Each ligand molecule is in contact with three of four subunits of the tetramer, hydrogen bonding with the side chain of Asp187 and the backbone carbonyl of residue 71, and electrostatically interacting with the backbone carbonyl of residue 51. The ligated complex adopts a quaternary structure between the canonical R- and T-states of fructose-1,6-bisphosphatase, and yet a dynamic loop essential for catalysis (residues 52-72) is in a conformation identical to that of the T-state enzyme. Inhibition by the pseudo-tetrapeptide is cooperative (Hill coefficient of 2), synergistic with both AMP and fructose 2,6-bisphosphate, noncompetitive with respect to Mg2+, and uncompetitive with respect to fructose 1,6-bisphosphate. The ligand dramatically lowers the concentration at which substrate inhibition dominates the kinetics of fructose-1,6-bisphosphatase. Elevated substrate concentrations employed in kinetic screens may have facilitated the discovery of this uncompetitive inhibitor. Moreover, the inhibitor could mimic an unknown natural effector of fructose-1,6-bisphosphatase, as it interacts strongly with a conserved residue of undetermined functional significance. 相似文献
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Aromatase and COX-2 expression in human breast cancers 总被引:8,自引:0,他引:8
Brodie AM Lu Q Long BJ Fulton A Chen T Macpherson N DeJong PC Blankenstein MA Nortier JW Slee PH van de Ven J van Gorp JM Elbers JR Schipper ME Blijham GH Thijssen JH 《The Journal of steroid biochemistry and molecular biology》2001,79(1-5):41-47
We have investigated aromatase and the inducible cyclooxygenase COX-2 expression using immunocytochemistry in tumors of a series of patients with advanced breast cancer treated with aromatase inhibitors. Aromatase was expressed in 58/102 breast cancers. This is similar to the percentage previously reported for aromatase activity. Interestingly, aromatase was expressed in a variety of cell types, including tumor, stromal, adipose, and endothelial cells. Since prostaglandin E2 is known to regulate aromatase gene expression and is the product of COX-2, an enzyme frequently overexpressed in tumors, immunocytochemistry was performed on the tissue sections using a polyclonal antibody to COX-2. Aromatase was strongly correlated (P<0.001) with COX-2 expression. These results suggest that PGE2 produced by COX-2 in the tumor may be important in stimulating estrogen synthesis in the tumor and surrounding tissue. No correlation was observed between aromatase or COX-2 expression and the response of the patients to aromatase inhibitor treatment. However, only 13 patients responded. Nine of these patients were aromatase positive. Although similar to responses in other studies, this low response rate to second line treatment suggests that tumors of most patients were no longer sensitive to the effects of estrogen. Recent clinical studies suggest that greater responses occur when aromatase inhibitors are used as first line treatment. In the intratumoral aromatase mouse model, expression of aromatase in tumors is highly correlated with increased tumor growth. First line treatment with letrozole was effective in all animals treated and was more effective than tamoxifen in suppressing tumor growth. Letrozole was also effective in tumors failing to respond to tamoxifen, consistent with clinical findings. In addition, the duration of response was significantly longer with the aromatase inhibitor than with tamoxifen, suggesting that aromatase inhibitors may offer better control of tumor growth than this antiestrogen. 相似文献
7.
DAZ family proteins exist throughout male germ cell development and transit from nucleus to cytoplasm at meiosis in humans and mice 总被引:17,自引:0,他引:17
Reijo RA Dorfman DM Slee R Renshaw AA Loughlin KR Cooke H Page DC 《Biology of reproduction》2000,63(5):1490-1496
The human DAZ gene family is expressed in germ cells and consists of a cluster of nearly identical DAZ (deleted in azoospermia) genes on the Y chromosome and an autosomal homolog, DAZL (DAZ-like). Only the autosomal gene is found in mice. Y-chromosome deletions that encompass the DAZ genes are a common cause of spermatogenic failure in men, and autosomal homologs of DAZ are essential for testicular germ cell development in mice and DROSOPHILA: Previous studies have reported that mouse DAZL protein is strictly cytoplasmic and that human DAZ protein is restricted to postmeiotic cells. By contrast, we report here that human DAZ and human and mouse DAZL proteins are present in both the nuclei and cytoplasm of fetal gonocytes and in spermatogonial nuclei. The proteins relocate to the cytoplasm during male meiosis. Further observations using human tissues indicate that, unlike DAZ, human DAZL protein persists in spermatids and even spermatozoa. These results, combined with findings in diverse species, suggest that DAZ family proteins function in multiple cellular compartments at multiple points in male germ cell development. They may act during meiosis and much earlier, when spermatogonial stem cell populations are established. 相似文献
8.
L. C. Emebiri M. E. Devey A. C. Matheson M. U. Slee 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(7):1062-1068
NESTUR (needle-to-stem unit rate) is a stem growth index of conifer seedlings that measures the efficiency of stemwood production
per unit of needle growth, and is related to other seedling traits such as height, stem diameter, stem volume and needle volume.
Quantitative trait loci (QTLs) affecting the expression of stem growth efficiency in radiata pine seedlings were investigated
using a RAPD linkage map constructed from markers scored on haploid, megagametophytic DNA. Four putative QTLs were detected
which accounted for 8.5–36.4% of the population variance. A search for evidence of epistasis, using both complete pairwise
and conditional interactions, did not yield any statistically significant result. Over a 3-year period, seedlings with high-NESTUR
marker alleles showed a superior growth performance of 17–40% for height, diameter and volume over those with low-NESTUR marker
alleles.
Received: 10 July 1997 / Accepted: 31 March 1998 相似文献
9.
Recent developments in the apoptosis field have uncovered a family of cysteine proteases, the Caspases, that act as signalling
components as well as effectors of the cell death machinery. Caspases are constitutively present as inactive precursors within
most cells and undergo proteolytic processing in response to diverse death-inducing stimuli to initiate the death programme.
Active caspases can process other caspases of the same type as well as process caspases further downstream in the pathway
that ultimately leads to collapse of the cell. This cellular collapse is thought to occur as a consequence of caspase-mediated
cleavage of a diverse array of cellular substrates. Regulation of entry into the death programme is controlled at a number
of levels by members of the Bcl-2 family, as well as by other cell death regulatory proteins. Recent data has shed light upon
the mechanism of action of these regulatory molecules and suggests that the point of caspase activation is a major checkpoint
in the cell death programme. Because many transformed cell populations possess derangements in cell death-regulatory genes,
such as bcl-2, such cells frequently exhibit elevated resistance to cytotoxic chemotherapy. Thus, a deeper understanding of
how apoptosis is normally regulated has therapeutic implications for disease states where the normal controls on the cell
death machinery have been subverted.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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