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Biomedical subjects

M M Goodman

Publications and source records attributed to M M Goodman.

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

Duplicated plastid and triplicated cytosolic isozymes of triosephosphate isomerase in maize (Zea mays L.).

We studied electrophoretic variation and inheritance of triosephosphate isomerase (TPI) isozymes in maize (Zea mays L.). In contrast to most diploid plants, in maize, TPI exists as multiple isozymes in both the plastid and cytosolic subcellular compartments. Phenotypes result from the overlay of two independent sets of isozymes and allozymes, representing the plastid (encoded by the nuclear genes Tpi1 and Tpi2) and cytosolic (encoded by Tpi3, Tpi4, and Tpi5) systems. All possible intragenic and intergenic dimeric enzymes are formed between polypeptides within each subcellular compartment. No heterodimers are formed between plastid and cytosolic polypeptides. Extensive surveys of accessions of land races and inbred lines revealed 22 allelic variants for the five loci. Most alleles have been formally validated by segregation analysis. We describe two null alleles at Tpi4, distinguished by their relative abilities to form intergenic heterodimers with polypeptides specified by Tpi3 and Tpi5. Linkage analyses and crosses with B-A translocation stocks were effective in determining the chromosome locations of all five loci. Duplicated genes for both the plastid and cytosolic isozymes were localized to genomic regions that possess numerous other redundant sequences. We placed Tpi1 on the long arm of chromosome 7, approximately 23 centimorgans (cM) distal to g11; we localized its duplicate--Tpi2--17 cM distal to v4 on the long arm of chromosome 2. The triplicate loci encoding cytosolic TPIs reside on chromosomes 3 and 8. Tpi4 is approximately equidistant (11 cM) from d1 and Lg3, near the centromere of chromosome 3. Tpi3 and Tpi5 are located on distal ends of the most poorly marked maize chromosome; Tpi3 is 29 cM distal to Idh 1 on 8L, and Tpi5 is on 8S or near the centromere on 8L. In contrast to most duplicated maize sequences, which often occur in parallel linkages on different chromosomes, Tpi3 and Tpi5 provide an example of intrachromosomal gene duplication. Several of the Tpi loci are located in sparsely mapped regions of the genome, and Tpi1 is the first isozyme marker for chromosome 7.

Alleles↗
PubMedDate not supplied

Genetic and germ plasm stocks worth conserving.

The relative costs and benefits of genetic stock collections and germ plasm collections are discussed. The status of national and international collections is compared with the needs of plant breeders and geneticists. There is an international need for germ plasm systems that emphasize the use and employment of materials rather than acquisition and storage. For base collections to function, they must provide for regeneration, characterization, documentation, and evaluation of their materials. The quality of a germ plasm system should be judged on the basis of the quality of the materials available to scientists. Adequate quantities of high-quality seed that are of known provenience, spanning the range of known genetic diversity, promptly delivered, and well described constitute the minimum that should be expected. All too often such minimal requirements are not met.

Gene Library↗
PubMedDate not supplied

Polymer-encapsulated PC-12 cells demonstrate high-affinity uptake of dopamine in vitro and 18F-Dopa uptake and metabolism after intracerebral implantation in nonhuman primates.

Intracranial implantation of polymer-encapsulated PC-12 cells has been shown to improve motor behavioral performance in animal models of Parkinson's disease. The purpose of this blinded study was to examine whether such improvement is associated with the active uptake and metabolism of dopamine precursors by intracerebrally implanted polymer-encapsulated PC-12 cells. In an in vitro experiment we demonstrate that 3H-dopamine uptake by PC-12 cells was 10(8) fmol/min x 10(6) cells, and that this uptake can be specifically blocked 88% by the addition of 10nM of nomifensine. In the in vivo experiments, polymer-encapsulated PC-12 cells were implanted in four MPTP-treated monkeys into the left deep parietal white matter (R1) or left striatum (R2-4). A fifth MPTP-treated monkey (R5) served as a control and received left striatal implants of empty capsules. 18-F-Dopa Positron Emission Tomography (PET) imaging was performed on each monkey before and after implantation surgery by blinded investigators. PET images obtained 5-13 wk after implantation demonstrated well delineated focal areas of high 18F-dopa uptake in R1, R2, and R4. The focal area of high 18F-dopa uptake in R1 precisely coregistered on a brain magnetic resonance image to the site of implantation. R3 (in whom the polymer-encapsulated PC-12 cells demonstrated poor cell survival upon explantation) and R5 (empty capsules) failed to demonstrate any area of increased 18F-dopa uptake in their PET images. Histological examination of the host brain revealed no sprouting of dopaminergic nerve terminals around the implantation sites of the polymer-encapsulated PC-12 cells. These results indicate that the previously noted behavioral improvement after intrastriatal implantation of polymer encapsulated PC-12 cells is at least in part due to their highly specific uptake and metabolism of dopamine precursors. Furthermore, these data suggest that polymer-encapsulated PC-12 cells can store, reuptake, and functionally replenish dopamine and therefore, may be an effective treatment for Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗