PubMed Health⌕ Search

Biomedical subjects

R Shalgi

Publications and source records attributed to R Shalgi.

78 records · Page 5Linked to original sources
PubMedDate not supplied

FISH-detected delay in replication timing of mutated FMR1 alleles on both active and inactive X-chromosomes.

X-chromosome inactivation and the size of the CGG repeat number are assumed to play a role in the clinical, physical, and behavioral phenotype of female carriers of a mutated FMR1 allele. In view of the tight relationship between replication timing and the expression of a given DNA sequence, we have examined the replication timing of FMR1 alleles on active and inactive X-chromosomes in cell samples (lymphocytes or amniocytes) of 25 females: 17 heterozygous for a mutated FMR1 allele with a trinucleotide repeat number varying from 58 to a few hundred, and eight homozygous for a wild-type allele. We have applied two-color fluorescence in situ hybridization (FISH) with FMR1 and X-chromosome alpha-satellite probes to interphase cells of the various genotypes: the alpha-satellite probe was used to distinguish between early replicating (active) and late replicating (inactive) X-chromosomes, and the FMR1 probe revealed the replication pattern of this locus. All samples, except one with a large trinucleotide expansion, showed an early replicating FMR1 allele on the active X-chromosome and a late replicating allele on the inactive X-chromosome. In samples of mutation carriers, both the early and the late alleles showed delayed replication compared with normal alleles, regardless of repeat size. We conclude therefore that: (1) the FMR1 locus is subjected to X-inactivation; (2) mutated FMR1 alleles, regardless of repeat size, replicate later than wild-type alleles on both the active and inactive X-chromosomes; and (3) the delaying effect of the trinucleotide expansion, even with a low repeat size, is superimposed on the delay in replication associated with X-inactivation.

Adolescent↗
PubMedDate not supplied

Loss of acid phosphatase from rat spermatozoa as a method for assessing the acrosome reaction.

A method is presented for evaluating the extent of the acrosome reaction by measuring the release of acrosomal acid phosphatase from rat spermatozoa during incubation under capacitating conditions. Treatment of spermatozoa with lysophosphatidylcholine or Triton X-100 released the acid phosphatase from the sperm cell. Using this enzymatic method we could not detect an alteration in enzyme activity following 5 h incubation under capacitating conditions. The effect of in vitro capacitation for 5 h in the absence or presence of heparin or ionophore A23187 was studied. Incubation in the presence of heparin (10 micrograms ml-1) caused a 32% increase in enzyme activity. After exposure of the spermatozoa to ionophore A23187 (0.5 microM) 16% increase of enzyme activity could be detected.

Acid Phosphatase↗
PubMedDate not supplied

Acrosomal status of human spermatozoa after follicular fluid or calcium ionophore challenge in relation to semen parameters and fertilizing capacity in vitro.

The proportion of spermatozoa that undergo spontaneous acrosome reaction in vitro is relatively low. The proportion can be enhanced by incubation with either biological inducers such as follicular fluid or chemicals like calcium ionophore. It has been suggested that improper acrosomal reaction may be a cause of fertilization failure in vitro. The objectives of the present study were to assess the acrosomal status of human sperm following follicular fluid or calcium ionophore treatment and to analyse the relationship between spontaneous and induced acrosome reaction and fertilization rates in vitro by standard in vitro fertilization (IVF) technology. In all, 53 semen samples (22 normal and 31 subnormal) were studied. The effect of calcium ionophore A 23187 and follicular fluid was assessed using the fluorescence activated cell sorter. IVF results were evaluated in relation to the acrosome status of the sperm samples. Our results demonstrate that the effect of follicular fluid on the acrosomal status correlated positively with the effect obtained by the calcium ionophore (Pearson's correlation r = 0.45). A significantly higher percentage of maximal acrosome change (P < 0.02) was found in cases where fertilization occurred (19/27), than in sperm samples that did not achieve fertilization in vitro (8/27). The present finding that follicular fluid induced acrosome reaction can serve as a predictive tool which is as good as the ionophore treatment for assessing IVF outcome, supports the use of this method for clinical purposes.

Acrosome↗