Search PubMed⌕ Search

Biomedical subjects

R McCarroll

Publications and source records attributed to R McCarroll.

6 recordsLinked to original sources
PubMed2000

Requirement of the spindle checkpoint for proper chromosome segregation in budding yeast meiosis.

The spindle checkpoint was characterized in meiosis of budding yeast. In the absence of the checkpoint, the frequency of meiosis I missegregation increased with increasing chromosome length, reaching 19% for the longest chromosome. Meiosis I nondisjunction in spindle checkpoint mutants could be prevented by delaying the onset of anaphase. In a recombination-defective mutant (spo11Delta), the checkpoint delays the biochemical events of anaphase I, suggesting that chromosomes that are attached to microtubules but are not under tension can activate the spindle checkpoint. Spindle checkpoint mutants reduce the accuracy of chromosome segregation in meiosis I much more than that in meiosis II, suggesting that checkpoint defects may contribute to Down syndrome.

Biomechanical Phenomena↗
PubMed2000

In reply

Explore the source record for details and available documents.

Journal Article↗
PubMed1996

Direct cloning of DNA sequences from the common fragile site region at chromosome band 3p14.2.

Despite several lines of evidence suggesting that common chromosomal fragile sites are biologically important as hot spots for recombination, their structure remains unknown. We showed previously that the plasmid pSV2neo preferentially integrates into bands containing fragile sites in cells transfected under conditions of fragile site induction. Here we report the isolation and characterization of the DNA sequences from two such independent integrations into 3p14.2, a common fragile site (FRA3B). These FRA3B region sequences were shown to lie within a 1330-kb YAC, 850A6, approximately 350 kb telomeric of the breakpoint of t(3;8), a constitutional rearrangement. The two integration sites are 10 kb apart, but each integration is associated with a deletion. We have constructed a partial genomic contig of the integration sites and deleted regions spanning approximately 85 kb. Analysis of the DNA sequences immediately surrounding the plasmid integrations revealed no known coding sequences or repeat structures resembling the (CGG)n motif characteristic of the rare fragile sites. In addition, by Southern blotting analysis, none of the phage clones isolated from the FRA3B region were found to contain CGG repeats. Fluorescence in situ hybridization analysis of genomic clones from this contig to metaphase cells induced to express breaks demonstrated hybridization adjoining the chromosome breaks, and occasionally the hybridization signal spanned the break. The results imply that breakage occurs at variable positions within a large region (at least on the order of 85 kb). Together, these data suggest that the structure of FRA3B differs from that of rare fragile sites.

Aphidicolin↗
PubMed1990

Microsurgical revascularization of ischemic rat femoral heads.

To demonstrate whether revascularization could be surgically induced in avascular bone the femoral heads of female albino rats were excised and drilled through and through. The femoral heads were then placed in the opposite thigh and by use of microvascular techniques the femoral artery was divided and lengthened with a 1 cm artery or vein graft, and reanastomosed after passing one end through the drilled hole in the transplanted femoral head. Arterial blood flowed through the graft within the drilled femoral head on its way to its normal distribution down the leg. Technetium 99m MDP methylene diphosphate, tetracycline labeling, latex injection, and histologic review were used to demonstrate new vessel growth. All grafts patent at the end of the experiment were associated with tetracycline labeling, positive technetium 99m methylene diphosphate counts and latex-filled vessels in the matrix of the femoral heads. Histologically the vascularized femoral heads showed evidence of neovascularization and new bone formation.

Anastomosis, Surgical↗
PubMed1983

Secondary structure of the Dictyostelium discoideum small subunit ribosomal RNA.

We have used comparative analyses of prokaryotic and eukaryotic small subunit ribosomal RNAs to deduce a secondary structure for the Dictyostelium discoideum 18S rRNA. Most of the duplex regions are evolutionarily conserved in all organisms. We have taken advantage of the variation to the D. discoideum sequence (relative to the yeast and frog 19S rRNAs) to identify additional helical regions which are common to the eukaryotic 18S rRNAs.

Animals↗