A 39 year old male with multiple dysmorphic features was found to have an unstable ring chromosome 7. Clinical findings are presented and compared with the other five reported cases of ring chromosome 7. The main characteristics found in patients with this chromosome constitution are prenatal onset growth deficiency, bone anomalies, pigmentary or vascular skin changes, and ocular and genital an...

We report on the cytogenetic and molecular investigations of constitutional de-novo ring chromosome 13s in three unrelated patients for better understanding and delineation of the phenotypic variability characterizing this genomic rearrangement. The patient's karyotypes were as follows: 46,XY,r(13)(p11q34) dn for patients 1 and 2 and 46,XY,r(13)(p11q14) dn for patient 3, as a result of the dele...

The first ring chromosome was described by Morgan (1933) 9 and originated from a crossing-over between attached X-chromosomes containing an inversion in Drosophila. Since then ring chromosome have been studied specially in Drosophila, maise and Man. Interest on ring chromosomes arises from the fact that some information may be disclosed regarding mechanism of chromatid splitting during mitosis ...

The (14)C production rate in the upper atmosphere changes with time because the galactic cosmic-ray flux responsible for (14)C production is modulated by the changes in solar wind magnetic properties. The resulting changes in the atmospheric (14)C level are recorded in tree rings and are used to calculate past (14)C production rates from a carbon reservoir model that describes terrestrial carbo...

Meiotic recombination between a circular and a linear chromosome in Saccharomyces cerevisiae has been investigated. The circle was a haploid-viable derivative of chromosome III constructed by joining regions near the two chromosome ends via a recombinant DNA construction: (HMR/MAT-URA3-pBR322-MAT/HML) and was also deleted for MAL2 (which therefore uniquely marks a linear chromosome III). Recomb...

Although ring chromosomes are observed in ahnost all autosomal groups in man, they are rare. We describe a male patient exldbiting cd du chat syndrome in which cytogenetic studies demonstrate the presonse of a ring chromosome 5. Deletion o£ the ring chromosome 5 is found between the p15 and q35 bands. Dental, medical and cytogenetic findings are compared to other ring chromosome 5 cases descMbe...

A cytogenetical study on 13 alfalfa (Medicago sativa) cultivars available in Iranian Forest and Rangelands Genebank was performed in order to obtain basic information on the variability in chiasma frequency/distribution, chromosome association and segregation. Such cytogenetic information is useful for planning hybridization programs. Cluster analysis of meiotic data and ordination of cultivars...