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Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
16.
ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome 总被引:11,自引:3,他引:11
Picketts DJ; Higgs DR; Bachoo S; Blake DJ; Quarrell OW; Gibbons RJ 《Human molecular genetics》1996,5(12):1899-1907
It was shown recently that mutations of the ATRX gene give rise to a
severe, X-linked form of syndromal mental retardation associated with alpha
thalassaemia (ATR-X syndrome). In this study, we have characterised the
full-length cDNA and predicted structure of the ATRX protein. Comparative
analysis shows that it is an entirely new member of the SNF2 subgroup of a
superfamily of proteins with similar ATPase and helicase domains. ATRX
probably acts as a regulator of gene expression. Definition of its genomic
structure enabled us to identify four novel splicing defects by screening
52 affected individuals. Correlation between these and previously
identified mutations with variations in the ATR-X phenotype provides
insights into the pathophysiology of this disease and the normal role of
the ATRX protein in vivo.
相似文献
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Interactive suppression of aberrant crypt foci induced by azoxymethane in rat colon by phytic acid and green tea 总被引:1,自引:2,他引:1
Several epidemiological studies point to a strong correlation between
nutrient composition of the diet and cancer of the colon. Phytic acid,
present in grains, has been credited with reducing the risk of cancer of
the colon. A number of reports are available indicating the benefits of
green tea consumption in reducing the risk of stomach, lung and skin
cancer, but little data are available on the effect of green tea in
reducing the risk of colon cancer. Also, there are no studies on the
combined effect of these compounds on colon tumorigenesis. Thus the primary
objective of this investigation was to elucidate the combined effects of
green tea and phytic acid on colonic preneoplastic lesions and the Phase II
enzyme glutathione S-transferase. Fisher 344 male weanling rats were
divided into nine groups of 15 rats each and fed the experimental diet for
13 weeks. Rats received two s.c. injections of azoxymethane in saline at 16
mg/kg body wt at 7 and 8 weeks of age. Rats received three levels (0, 1 and
2%) of phytic acid with three levels (0, 1 and 2%) of green tea within each
phytic acid level in a 3 x 3 factorial experiment. Results indicate that
while green tea had a marginal effect (P < 0.14), phytic acid
significantly reduced the incidence of aberrant crypt foci (P < 0.008).
The interaction between green tea and phytic acid was significant (P <
0.029 for distal and < 0.0168 for entire colon) and positive, pointing
to a synergistic effect of green tea and phytic acid.
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