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701.
The effect of colony age on PCR fingerprinting 总被引:3,自引:1,他引:2
H. L. C. Coutinho B. A. Handley H. E. Kay L. Stevenson J. E. Beringer 《Letters in applied microbiology》1993,17(6):282-284
The pattern of DNA fragments produced by the polymerase chain reaction using arbitrary primers is strongly influenced by the age of the colonies sampled. We show that the number, clarity and reproducibility of the bands produced is optimal when very young colonies are sampled.
This work was supported by European Community grants (EEC CI1* 0545-UK, JEB and HC; BIOT-CT91-0283, JEB and HK), the AFRC (PG7 586, JEB and BH) and the SERC Biotechnology Directorate and Zeneca Ltd through a CASE studentship to LS. 相似文献
This work was supported by European Community grants (EEC CI1* 0545-UK, JEB and HC; BIOT-CT91-0283, JEB and HK), the AFRC (PG7 586, JEB and BH) and the SERC Biotechnology Directorate and Zeneca Ltd through a CASE studentship to LS. 相似文献
702.
F. A. B. Coutinho L. F. Lopez M. N. Burattini E. Massad 《Bulletin of mathematical biology》2001,63(6):1041-1062
The variation of viraemia in the natural course of HIV infection is expected to have major influence on the probability of
transmission and, consequently, on the epidemiology of HIV/AIDS.
In this paper we propose a model which takes into account the time evolution of HIV viraemia (measured as HIV-RNA copies per
ml of blood) in an infected individual and its impact on the threshold for the establishment of an endemic level, and mainly
on the relative contribution of each of the clinical phases of the infection to the total transmission of HIV per infected
individual.
We consider that an infected individual passes through three phases of viraemia. The first phase, which lasts for 6–7 weeks,
is characterized by very high viraemia. In the second phase, which lasts about 10 years, the viraemia is much lower, increasing
again in the last phase, which lasts up to two years, and ends in full-blown AIDS.
We show that the relative contribution of each phase to the total transmission of HIV is very sensitive to the model we assume
for the dependence of the transmissibility of HIV on the viral load. For instance, if we assume that transmissibility is proportional
to the decimal logarithm of viraemia, then the second phase predominates always. Due to the epidemiological importance of
this fact, it is clear that further improvement on virological research to better understand the dependence of HIV transmissibility
on the viral concentration in biological fluids is necessary. 相似文献
703.
J. B. Coutinho B. Moser D. G. Kilburn R. A. J. Warren R. C. Miller Jr 《Molecular microbiology》1991,5(5):1221-1233
The cenC gene of Cellulomonas fimi, encoding endoglucanase CenC, has an open reading frame of 1101 codons closely followed by a 9 bp inverted repeat. The predicted amino acid sequence of mature CenC, which is 1069 amino acids long, is very unusual in that it has a 150-amino-acid tandem repeat at the N-terminus and an unrelated 100-amino-acid tandem repeat at the C-terminus. CenC belongs to subfamily E1 of the beta-1,4-glycanases. High-level expression in Escherichia coli of cenC from a 3.6 kbp fragment of C. fimi DNA leads to levels of CenC which exceed 10% of total cell protein. Most of the CenC is in the cytoplasm in an inactive form. About 60% of the active fraction of CenC is in the periplasm. The catalytic properties of the active CenC are indistinguishable from those of native CenC from C. fimi. The Mr of CenC from E. coli and C. fimi is approximately 130 kDa. E. coli and C. fimi also produce an endoglucanase, CenC', of approximate Mr 120kDa and with the same N-terminal amino acid sequence and catalytic properties as CenC. CenC' appears to be a proteolytic product of CenC. CenC and CenC' can bind to cellulose and to Sephadex. CenC is the most active component of the C. fimi cellulase system isolated to date. 相似文献
704.
V beta 17 gene polymorphism in wild-derived mouse strains: two amino acid substitutions in the V beta 17 region greatly alter T cell receptor specificity 总被引:16,自引:0,他引:16
P A Cazenave P N Marche E Jouvin-Marche D Voegtlé F Bonhomme A Bandeira A Coutinho 《Cell》1990,63(4):717-728
Of 41 wild-derived mouse strains analyzed, 14 contained T cells bearing V beta 17 receptors in spite of the concomitant expression of I-E antigens. Reciprocal F1 and F2 hybrids of one of these strains, PWK, with laboratory strains revealed different patterns of V beta 17 T cell deletions from those observed with V beta 17 T cells from SJL, implying that the two V beta 17 regions are associated with recognition of distinct superantigens. The structures of the V beta 17 alleles differ by two amino acid substitutions, which lie together in an area distant from the predicted site of T cell receptor interaction with peptide-MHC complexes but overlapping with that implicated in V beta 8.2 recognition of Mls-1 superantigen. This demonstrates that the self-superantigen leading to V beta 17 T cell deletion varies with the allele of the receptor gene and confirms that T cell deletions by such ligands involve interactions with a region of the V beta domain that is distinct from the conventional combining site. 相似文献