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991.
992.
993.
Multiple copies of a DNA sequence from Pseudomonas syringae pathovar phaseolicola abolish thermoregulation of phaseolotoxin production 总被引:3,自引:0,他引:3
Karla B. Rowley David E. Clements Morton Mandel Tom Humphreys Suresh S. Patil 《Molecular microbiology》1993,8(3):625-635
Phaseolotoxin, a phytotoxin of Pseudomonas syringae pv. phaseolicola, is produced at 18°C but not at 28°C. Here we report that a fragment (24.4 kb) cloned from the wild-type strain, which does not harbour a gene(s) involved in phaseolotoxin biosynthesis, abolishes this thermoregulation in the wild type and suppresses a Tox? mutant at both temperatures. A subclone harbouring a 465bp fragment contains motifs that are characteristic of DNA-binding sites. In mobility shift assays we have detected a protein(s) from the wild-type and the mutant strains, grown at appropriate temperatures, that specifically binds to the fragment containing the DNA-binding motifs. We propose that the binding protein is a repressor which is ‘titrated’ by this fragment when it is present in the cell on a multiple copy plasmid, thus allowing expression of phaseolotoxin genes. 相似文献
994.
Human red and green visual pigment genes are X-linked duplicate genes. To
study their evolutionary history, introns 2 and 4 (1,987 and 1,552 bp,
respectively) of human red and green pigment genes were sequenced.
Surprisingly, we found that intron 4 sequences of these two genes are
identical and that the intron 2 sequences differ by only 0.3%. The low
divergences are unexpected because the duplication event producing the two
genes is believed to have occurred before the separation of the human and
Old World monkey (OWM) lineages. Indeed, the divergences in the two introns
are significantly lower than both the synonymous divergence (3.2% +/- 1.1%)
and the nonsynonymous divergence (2.0% +/- 0.5%) in the coding sequences
(exons 1-6). A comparison of partial sequences of exons 4 and 5 of human
and OWM red and green pigment genes supports the hypothesis that the gene
duplication occurred before the human-OWM split. In conclusion, the high
similarities in the two intron sequences might be due to very recent gene
conversion, probably during evolution of the human lineage.
相似文献
995.
Three Indian cultivars ofL. esculentum were assessed for shoot regeneration from protoplast-derived calli. Consistent yields of viable protoplasts (>9.0×106 g f.wt.-1) were obtained from leaflets of 14 days old cultured shoots. Protoplast viability (88–94%) and planting efficiency (55–70%) were recorded for the three cultivars. Up to 71% of the protoplast-derived tissues regenerated shoots.Abbreviations BAP
6-benzylaminopurine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- g f.wt.
gram fresh weight
- IAA
indoleacetic acid
- MS
Murashige & Skoog (1962)
- NAA
-naphthaleneacetic acid
- Zea
zeatin 相似文献
996.
Anthony J. Cousineau Ronald M. Lauer Mary Ella Pierpont Trudy L. Burns Robert H. Ardinger Shivanand R. Patil Val C. Sheffield 《Human genetics》1994,93(2):103-108
The association between trisomy 21 and a high incidence of atrioventricular canal defects (AVCDs) indicates that a locus on chromosome 21 is involved in this congenital heart defect. We have investigated whether a genetic locus on chromosome 21 is also involved in familial nonsyndromic AVCDs. Short tandem repeat polymorphisms (STRPs) from chromosome 21 were used for linkage analysis of a family having multiple members affected with AVCDs. In this family, the gene for AVCDs is transmitted as an autosomal dominant with incomplete penetrance. The affected family members are nonsyndromic and have normal karyotypes. Two-point and multipoint linkage analyses produced significantly negative LOD scores for all informative markers. A comparison of the overlapping exclusion distances obtained for each marker at LOD equal -2.0 with the 1000:1 consensus genetic map of the markers, excludes chromosome 21 as the genetic location for AVCDs in this family. The exclusion of chromosome 21 indicates that another gene, not located on chromosome 21, is involved in atrioventricular canal defect formation. 相似文献
997.
Distinguishing benign from malignant pleural effusions by lectin immunocytochemistry 总被引:1,自引:0,他引:1
Since distinguishing malignant from benign cells in pleural effusions can be difficult, with reactive mesothelial cells simulating adenocarcinoma cells, the binding patterns of a battery of lectins on cells in eight benign and eight malignant effusions were studied using the avidin-biotin peroxidase complex method. The following lectins were used: concanavalin A, Dolichos biflorus agglutinin, peanut agglutinin, Phaseolus vulgaris agglutinin, Ricinus communis germ agglutinin, soybean agglutinin, Ulex europeaus agglutinin (UEA) and wheat germ agglutinin. Several patterns of staining were seen with the lectins, but only UEA was helpful in distinguishing between benign and malignant effusions. Sixty percent of the adenocarcinomas stained with UEA, whereas none of the cells in the benign effusions did. These results imply that UEA positivity is indicative of carcinoma and can be useful in separating reactive or atypical mesothelial cells from adenocarcinoma cells. 相似文献
998.
Summary A protocol of purification is devised that gave high recovery of homogeneous arginase from ox erythrocytes. The protocol involved haemolysis, heat treatment, CM- and DEAE-Sepharose chromatography, arginine AH-Sepharose chromatography and molecular sieving through Biogel P-150, all in the presence of 2-mercaptoethanol. It afforded (a) elution of arginase as a single peak, (b) almost 2900 fold purification, (c) 30% recovery and (d) electrophoretically homogeneous arginase. The purified arginase exhibited (a) M.W. of 115,000, (b) dissociation upon SDS treatment into homologous monomers of 30 kDa, (c) optimum pH and temperature 11.5 and 55° C, respectively and (d) Km value for L-arginine-HCl 2.2–2.3 mM, characteristic of the ureotelic type. 相似文献
999.
Alan J. Henderson Mark Hadden Cheng Guo Neema Douglas Helene Decornez Mark R. Hellberg Andrew Rusinko Marsha McLaughlin Naj Sharif Colene Drace Raj Patil 《Bioorganic & medicinal chemistry letters》2010,20(3):1137-1140
Inhibition of rho kinase (ROCK) has been recognized as an important target for a number of diseases, including glaucoma. Herein we report SAR development around two hits from a kinase library that led to the discovery of the ROCK inhibitor compound 38. In vitro and in vivo analysis of this compound, including its effects in a monkey model of glaucoma will be discussed. 相似文献
1000.
The purpose of the present study was to investigate the potential use of two PEGylated derivatives of rosin (PD) as sustained
release film forming materials. The derivatives differed chemically by their acid numbers—PD-1 with 120.93 and PD-2 with 88.19.
The derivative films were characterized for surface morphology, water uptake-weight loss, angle of contact, water vapor transmission
rate, mechanical properties and permeability study. Dissolution of diclofenac sodium (DS) and propranolol hydrochloride (PHL)
as model drugs was studied from coated pellets. The films of derivatives with and without plasticizers were smooth and continuous.
PD-2 films developed greater numbers of pores when in contact with phosphate buffer pH 6.8. The low weight loss, low angles
of contact and high water vapor transmission rate of PD-2 films were related to presence of higher concentration of PEG esters.
Higher tensile strength and percent elongation of PD-2 films was due to greater degree of internal plasticization of the derivative.
The permeability of films to model drugs propranolol hydrochloride and diclofenac sodium was inversely proportional to the
film thickness and dibutyl phthalate concentration in them; the permeability being greatest in PD-2 films containing 10% PEG
200. Dissolution rate of propranolol hydrochloride was higher from the coated pellets. The dissolution data followed zero
order, Baker–Lonsdale equation and Hixon–Crowell equation of release kinetics with high correlation coefficients. The mechanism
of drug release from these coated systems however followed class II transport (n > 1.0). The derivatives investigated could successfully retard release of the model drugs and offers an alternative to the
conventionally used polymers. 相似文献