Browsing by Subject "Isoenzymes"
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Item Allozyme investigation of the isoetes riparia alltetraploid complex(Texas Tech University, 1998-12) Caplen, Cynthia AnnThis thesis addresses a systematic problem within Isoetes, a genus comprising approximately 150 species worldwide, 25 of which are currently known from North America. Isoetes is the sole extant genus of Isoetaceae which, along with Lycopodiaceae and Selaginellaceae, are the extant families of Lycopodiophyta, the most primitive division of vascular plants. Isoetes is heterosporous, i.e., producing sexually dimorphic spores, an apomorphic condition shared via convergence with spermatophytes but restricted among pteridophytes to a few taxa. Isoetes microspores (male) are usually less than 50 microns in diameter while megaspores (female) are mostly greater than 300 microns in di£mieter (Taylor et al. 1993). Isoetes comprises herbaceous perennials with a very simple yet unique form. This uniqueness in form helps to distinguish Isoetes from other kinds of plants, but their simplicity poses difficulty in species identification due to a resultant lack of taxonomic characters. Isoetes plants have a small, lobed, subterranean stem (corm) from which a spiral array of terete to angular quill-like microphylls (leaves) ascend, acheiving lengths of 1 to 100 cm. Each microphyll possesses either a microsporangium or a megasporangium that develops on the adaxial side of the expanded microphyll base. Sporangia are covered to varying degrees by a thin layer of tissue, the velum (Taylor et al. 1993).Item Central cell incongruity as a barrier to introgression in (Allium cepa L. x A. fistulosum L.) x A. cepa backcross F1BC3 generations(Texas Tech University, 2001-08) Mangum, Paul D.Polyacrylamide gel electrophoresis (PAGE) was used to study the inheritance of esterase isozyme (EST) phenotypes in Allium fistulosum L. Three A. fistulosum specific loci were identified from the most anodal zones of acitivity, EST-1, EST-4, EST-6. Each locus was found to have two alleles. Both EST-1 and EST-4 encode a null allele. Plants homozygous for the nuli atieies lacked expression of the respective band on the PAGE gel. Starch gel electrophoresis was used to study the inheritance of the Phosphoglucoisomerase (PGI) phenotype. Pgi-1 in A. fistulosum has two alleles, Pgi-1^, and Pgi-1'*. Goodnessof-fit of these alleles to Mendelian ratios was tested in an F2 population with the chi-square statistic. Linkage analysis was also conducted befr.vscn the new alleles presented in this report and with previously identified alleles of ADH, 6-PGDH, and PGM. An incongruity model is presented as a possible expiaiiaiiun for an anomaly in the germination and establishment percentages, as well as a distorted isozyme segregation pattern, observed in F2BG3 seed of an A. cepa x A. fistulosum interspecific hybrid. The F1BG3 parent expressed Pgi-1^, PGI alleles of both species; Pgi-1^ coming from A. cepa (Ac) and Pgi-1^ allele from A. fistulosum (Af). Data collected on the F2BG3 progeny population were percent germination and establishment, segregation of Ac and Af Pgi-1 alleles, and viability and genotype of non-germinated seed, seed that was not planted, and isolated embryo and endosperm tissue. Seed, embryo, and endosperm tissues exhibited 100% viability, despite lower germination and establishment peicentayes.. A pooled goodness-of-fit test of the segregation of Pgi-1 alleles in the populations to the expected Mendelian 1:2:1 ratio using the chi-square statistic gave a x^ = 185.9, well beyond the accepted limits at 2 degrees of freedom, and the 1:2:1 ratio was rejected. Another pooled chi-square goodness-of-fit test of the segregation of Pgi-1 alleles in the populations to a 1:1 ratio based on the incongruity model gave a x^ = 0.203, within the accepted limits at 2 degrees of freedom and the 1:1 ratio was not rejected. Chi-square tests of data from other populations reporting similar to PGI isozyme distortion suppoit the hypothesis.Item Electrophoretic studies of relationships within the genus Artibeus (Chiroptera: Phyllostomidae)(Texas Tech University, 1982-08) Koop, Benjamin FNot availableItem Function and regulation of two methylenetetrahydrofolate reductase isozymes in Saccharomyces cerevisiae(2003-12) Chan, Sherwin Yum-Yat, 1973-; Appling, Dean Ramsay