In:
American Journal of Medical Genetics, Wiley, Vol. 23, No. 1-2 ( 1986-01), p. 429-443
Abstract:
We have extended our previous studies of fra(X) expressionin somatic cell hydrids to the analysis of a carrier female with a low level of expression and to an unaffected, transmitting male who shows no expression in lymphocytes or lymphoblasts. Optimum conditions for fra(X) expression was treatment with 10 −8 M FUdR for 16 hours. In recent experiments, addition of 2.2 mM caffeine 2 hours before harvest was found to increase expression consistently. Two clones from the carrier female containing the far(X) chromiosome but not the normal X showed expression of 2–4%, indicating that expression in heterozygous females is not influenced by the presence or absence of the normal X. Expression rate was increased to 20% by exposure to FUdR plus caffeine. Analysis of hybrids containing only the fra(X) in an inactive state, and after reactivation by 5‐azacytidine, showed no change in the frequency of expression. A hybrid clone from the nonexpressing, transmitting male containing only the X and chromosome 13, showed expression rangine from 2% without caffeine to 12% with caffeine in three different experiments. The ability to induce fra(X) expression n hybrid from this nonexpressing male may be explained in one of several ways: (1) a second mutation has occurred, (2) an autosomal suppressor locus was lost, or (3) the hamster genome or unusually short cell cycle lowers the threshold for expression, particularly in presence of caffeine.
Type of Medium:
Online Resource
ISSN:
0148-7299
,
1096-8628
DOI:
10.1002/ajmg.v23:1/2
DOI:
10.1002/ajmg.1320230135
Language:
English
Publisher:
Wiley
Publication Date:
1986
detail.hit.zdb_id:
2143866-3
detail.hit.zdb_id:
2143867-5
detail.hit.zdb_id:
1493479-6
detail.hit.zdb_id:
2205916-7
SSG:
12
Permalink