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排序方式: 共有470条查询结果,搜索用时 15 毫秒
1.
The local chromatin structure of the Shrunken-1 (Sh) gene of maize was probed by analyzing DNase I hypersensitivity. Sh encodes the gene for sucrose synthetase, a major starch biosynthetic enzyme, which is maximally expressed in the endosperm during seed maturation. In addition to general DNase I sensitivity, specific DNase I hypersensitive sites were identified in endosperm chromatin that mapped near the 5 end of the Sh gene. The pattern of hypersensitive sites and their relative sensitivity were altered in other non-dormant tissues that produce little or no enzyme. However, some changes in chromatin structure appear to be independent of Sh gene expression and may reflect general alterations associated with plant development. The chromatin structure of several sh mutations, induced by Ds controlling element insertions, was also analyzed. Although the insertions perturbed expression of the gene, there were no notable effects on local chromatin structure. 相似文献
2.
Kinetic continuum models are derived for cells that crawl over a 2D substrate, undergo random reorientation, and turn in response to contact with a neighbor. The integro-partial differential equations account for changes in the distribution of orientations in the population. It is found that behavior depends on parameters such as total mass, random motility, adherence, and sloughing rates, as well as on broad aspects of the contact response. Linear stability analysis, and numerical, and cellular automata simulations reveal that as parameters are varied, a bifurcation leads to loss of stability of a uniform (isotropic) steady state, in favor of an (anisotropic) patterned state in which cells are aligned in parallel arrays. 相似文献
3.
ECTOMYCORRHIZA FORMATION IN EUCALYPTUS 总被引:9,自引:8,他引:1
4.
The small (116 amino acids) inner membrane protein MerT encoded by the transposon Tn501 has been overexpressed under the control of the bacteriophage T7 expression system. Random mutants of MerT were made and screened for loss of mercuric ion hypersensitivity. Several mutantmerT genes were selected and sequenced: Cys24Arg and Cys25Tyr mutations abolish mercury resistance, as do charge-substitution mutations in the first predicted transmembrane helix (Glyl4Arg, Glyl5Arg, Gly27Arg, Ala18Asp), and the termination mutations Trp66Ter and Cys82Ter. 相似文献
5.
Mohammad B. Rashid Katsuhiko Shirahige Naotake Ogasawara Hiroshi Yoshikawa 《Gene》1994,150(2):213-220
We have analyzed the relationship between autonomously replicating sequence (ARS) structure and function for three ARS (ARS605, ARS607 and ARS609) from chromosome VI of Saccharomyces cerevisiae by systematic XhoI-linker mutation in the ARS consensus sequence (ACS) and flanking sequences. All mutations that encroached upon the ACS destroyed ARS activity. DNA sequences stimulative for ARS function were identified on either side of the ACS of ARS605 and only on the 3'-side of the ACS of ARS607. In ARS609, however, no such stimulative sequences were observed. Base substitutions complementary to the wild-type sequence of those stimulative regions, in ARS605 and ARS607, that did not change the AG of unwinding nor affected ARS activity suggests that these regions have, at least, a function as DNA-unwinding elements (DUE). ARS605, ARS607 and ARS609 DNA are of low AG value and showed hypersensitivity to single-strand-specific nuclease when inserted in negatively supercoiled plasmid. Linker mutations inhibitory for ARS activity (5L11 and 7L14) also caused significant changes in local nucleotide (nt) sensitivity within the ACS and its adjoining regions. Complementary base substitutions, however, did not affect these changes in local nt sensitivity. These results imply that the stimulative regions flanking the ACS are necessary to produce an optimum conformation around the ACS which may be important for full ARS activity. 相似文献
6.
7.
《Indian pacing and electrophysiology journal》2023,23(1):21-22
Contact allergy to implantable cardiac defibrillators (ICD) is an uncommon and underdiagnosed complication. We report a case of a 20-years-old man patient that was resuscitated from sudden cardiac death. Workup imaging study was unremarkable, but genetic testing identified a mutation in the KCNH2 gene of uncertain significance. The patient underwent a subcutaneous implantable cardiac defibrillator (S-ICD) implantation, with no complications. The patient suffered two hospital re-admissions due to a device-related inflammatory reaction, leading to two device re-implantations. At the first time, it was considered a bacterial infection and the S-ICD was replaced by an endovascular device. At the second time, a tissue-device interaction, with hypersensitivity reaction and device rejection was suspected. The skin patch-tests were inconclusive, but it was decided to implant a custom-made gold-coated endovascular ICD. Indeed, the tendency is an initial misdiagnosis as an infection and a high clinical suspicion is essential to an early diagnosis. 相似文献
8.
Shigeki Nagao Yoshihiro Kawabata Takashige Nishikawa Haruhiko Takada 《Microbiology and immunology》1995,39(12):1011-1014
Guinea pigs immunized with Freund's complete adjuvant received challenge injection of the purified protein derivative of Mycobacterium tuberculosis in the flanks and the corneas to prepare delayed-type hypersensitivity (DTH) reactions. The animals were injected subcutaneously with lipopolysaccharide (LPS) or a synthetic lipid A (LA-15-PP). At the skin site primed with DTH reaction, increased swelling and hemorrhagic reaction followed by a definite necrotic reaction occurred. Severe corneal reactions were also observed in the animals. These findings indicate that bacterial endotoxin modulates DTH reactions and induces severe inflammatory reactions. 相似文献
9.
10.
Strong adjuvant action of Klebsiella O3 lipopolysaccharide and its inhibition of systemic anaphylaxis 总被引:1,自引:0,他引:1
T. Yokochi Y. Inoue Y. Kato T. Sugiyama G.-Z. Jiang M. Kawai M. Fukada K. Takahashi 《FEMS immunology and medical microbiology》1995,10(3-4):181-184
Abstract Immunization with lipopolysaccharide from Klebsiella O3 as an immunological adjuvant did not cause the death of mice in systemic anaphylaxis to bovine serum albumin. On the other hand, most mice immunized with lipopolysaccharide from Escherichia coli O111, Klebsiella O4 and Salmonella minnesota did die. Klebsiella O3 lipopolysaccharide enhanced IgM and IgG antibody response to BSA more markedly than Escherichia coli O111 lipopolysaccharide, while it affected the production of IgE antibody only slightly. Therefore, it is suggested that the inhibition of systemic anaphylaxis by Klebsiella O3 lipopolysaccharide adjuvant might be related to its strong adjuvant action on IgM and IgG class antibody production, and that high levels of circulating IgM and IgG antibodies might act as blocking antibodies in the development of IgE-mediated systemic anaphylaxis. 相似文献