In vitro cultivation of cells from aneuploid human embryos. Initiation of cell lines and longevity of the cultures.

During a cytogenetic study of human spontaneous abortions, attempts were made to initiate cell lines from tissues of embryos with chromosomal anomalies. The rate of success of these attempts and the life-span of the cell cultures is correlated with the development attained by these aneusomic embryos.     

Linkage disequilibrium between the fragile X mutation and two closely linked CA repeats suggests that fragile X chromosomes are derived from a small number of founder chromosomes

In order to investigate the origin of mutations responsible for the fragile X syndrome, two polymorphic CA repeats, one at 10 kb (FRAXAC2) and the other at 150 kb (DXS548) from the mutation target, were analyzed in normal and fragile X chromosomes. Contrary to observations made in myotonic dystrophy, fragile X mutations were not strongly associated with a single allele at the marker loci. However, significant differences in allelic and haplotypic distributions were observed between normal and fragile X chromosomes, indicating that a limited number of primary events may have been at the origin of most present-day fragile X chromosomes in Caucasian populations. We propose a putative scheme with six founder chromosomes from which most of the observed fragile X–linked haplotypes can be derived directly or by a single event at one of the marker loci, either a change of one repeat unit or a recombination between DXS548 and the mutation target. Such founder chromosomes may have carried a number of CGG repeats in an upper-normal range, from which recurrent multistep expansion mutations have arisen.     

Are cysteine,glutathione and phytochelatins responses of Myriophyllum alterniflorum to copper and arsenic stress affected by trophic conditions?

BioMetals - The aim of this article is to study the impact of both copper (Cu2+) and arsenic (As (V)) at 100 µg/L, with each element being combined with trophic conditions at the...     

Molecular analysis of a ring chromosome X in a family with fragile X syndrome

The phenotypically normal sister of a patient affected by fragile X syndrome was referred for genetic counselling and was found to carry a mosaic karyotype 46,X,r(X)/45,X. Because the probability of the simultaneous chance occurrence of fragile X syndrome and a ring chromosome X in the same family is very low, we postulated that the breakpoint of the ring chromosome X originated in the cytogenetic break in Xq27.3 responsible for fragile X syndrome. In order to determine the relative positions of the breakpoint on the ring chromosome X and the (CGG)n unstable sequence responsible for the fragile X mutation, we used molecular markers to analyse the telomeric regions of chromosome X in this family. The results showed that the ring chromosome X was the maternal fragile X chromosome and that the telomeric deletion on the long arm encompassed the (CGG)n sequence. This suggests that the cytogenetic break in Xq27.3 is distinct from the unstable (CGG)n sequence, or that the break followed by the end-to-end fusion creating the ring chromosome was not completely conservative. Analysis of DNA markers on the short arm of chromosome X evidenced a deletion of a large part of the pseudoautosomal region, allowing us to position the genes involved in stature and in some syndromes associated with telomeric deletions of Xp on the proximal side of the pseudoautosomal region.     

Identification by Q and G bands of chromosome anomalies in spontaneous abortion]

Banding technique were applied to cell lines which had been established earlier from spontaneous human abortions and preserved frozen. Most of the autosomes were shown to be involved in lethal trisomies. As a result of the precise identification of affected chromosomes, the exact time of developmental arrest as well as certain phenotypes could be correlated with the various trisomies.