Biomedical subjects

Peter Shaw

Publications and source records attributed to Peter Shaw.

22 records · Page 2Linked to original sources

PubMed2003

AHP2 is required for bivalent formation and for segregation of homologous chromosomes in Arabidopsis meiosis.

A new Arabidopsis meiotic mutant has been isolated. Homozygous ahp2-1 (Arabidopsis homologue pairing 2) plants were sterile because of failure of both male and female gametophyte development. Fluorescent in situ hybridisation showed that in ahp2-1 male meiocytes, chromosomes did not form bivalents during prophase I and instead seemed to associate indiscriminately. Chromosome fragmentation, chromatin bridges and unbalanced segregation were seen in anaphase I and anaphase II. The ahp2-1 mutation was caused by a T-DNA insertion in an Arabidopsis homologue of meu13+, which has been implicated in homologous chromosome pairing during meiosis in Schizosaccharomyces pombe. Our results suggest that meu13+ function is conserved in higher eukaryotes and support the idea that Arabidopsis, yeast and mouse share a pairing pathway that is not present in Drosophila melanogaster and Caenorhabditis elegans.

Amino Acid Sequence↗

PubMed2003

Chromosomes form into seven groups in hexaploid and tetraploid wheat as a prelude to meiosis.

Hexaploid wheat possesses 42 chromosomes derived from its three ancestral genomes. The 21 pairs of chromosomes can be further divided into seven groups of six chromosomes (one chromosome pair being derived from each of the three ancestral genomes), based on the similarity of their gene order. Previous studies have revealed that, during anther development, the chromosomes associate in 21 pairs via their centromeres. The present study reveals that, as a prelude to meiosis, these 21 chromosome pairs in hexaploid (and tetraploid) wheat associate via the centromeres into seven groups as the telomeres begin to cluster. This results in the association of multiple chromosomes, which then need to be resolved as meiosis progresses. The formation of the seven chromosome clusters now explains the occasional occurrence of remnants of multiple associations, which have been reported at later stages of meiosis in hexaploid (and tetraploid) wheat. Importantly, the chromosomes have the opportunity to be resorted via these multiple interactions. As meiosis progresses, such interactions are resolved through the action of loci such as Ph1, leaving chromosomes as homologous pairs.

Centromere↗

PubMed2003

Pharmacogenetics and pharmacogenomics in drug development and regulatory decision making: report of the first FDA-PWG-PhRMA-DruSafe Workshop.

The use of pharmacogenetics and pharmacogenomics in the drug development process, and in the assessment of such data submitted to regulatory agencies by industry, has generated significant enthusiasm as well as important reservations within the scientific and medical communities. This situation has arisen because of the increasing number of exploratory and confirmatory investigations into variations in RNA expression patterns and DNA sequences being conducted in the preclinical and clinical phases of drug development, and the uncertainty surrounding the acceptance of these data by regulatory agencies. This report summarizes the outcome of a workshop cosponsored by the Food and Drug Administration (FDA), the Pharmacogenetics Working Group (PWG), the Pharmaceutical Research and Manufacturers of America (PhRMA), and the PhRMA Preclinical Safety Committee (DruSafe). The specific aim of the workshop was to identify key issues associated with the application of pharmacogenetics and pharmacogenomics, including the feasibility of a regulatory "safe harbor" for exploratory genome-based data, and to provide a forum for industry-regulatory agency dialogue on these important issues.

Clinical Trials as Topic↗

PubMed2002

3D gold in situ labelling in the EM.

We have developed a novel pre-embedding in situ hybridization labelling method for electron microscopy which has given much greater sensitivity and higher labelling levels than have been achieved previously, together with good ultrastructural preservation. Vibratome sections of plant tissue were labelled throughout their thickness with 1 nm gold antibodies and then silver enhanced, embedded in resin and sectioned for electron microscopy. Because the labelling extends throughout the depth of the specimen, this method permits the study of the 3D arrangement of the labelling at the electron microscope level by either stereo-pair recording, tomographic reconstruction or 3D reconstruction from serial sections. In this paper we describe the application of this method to study the organization of rDNA in pea root tissue.

Cell Nucleolus↗