Schwanniomyces occidentalis (Debaryomyces occidentalis ) is able to grow rapidly with high cell mass on cheap starch as a carbon source, produce strong amylolytic enzymes extracellularly and secrete large proteins without hyper-glycosylation and measurable extracellular proteases. Schw. occidentalis thus has a high potential as, a useful alternative to Saccharomyces cerevisiae in the production of heterologous proteins. However, the molecular study of Schw. occidentalis has been very limited due to the insufficient transformation system and lack of gene expression information. / A new transformation system of Schw. occidentalis has been developed. This system was based on vector YEp13 ( LEU2) and a stable leu auxotrophic mutant, Schw. occidentalis DW88, obtained by treating the yeast with 1-methyl-3-nitro-1-nitrosoguanidine. The transformation efficiency of YEp13 by spheroplast-mediating method was 103 transformants/mug DNA. The 2-mum replicon is proposed to be responsible for YEp13 replication in Schw. occidentalis. The YEp13 stability in Schw. occidentalis was low, but it kept its structure in the yeast, suggesting that Schw. occidentalis DW88 does not modify foreign DNA. / After analysis of 14 cloned Schw. occidentalis genes and comparison of associated genes from both Schw. occidentalis and S. cerevisiae, 25 codons were arbitrarily chosen as putative preferred codons for Schw. occidentalis. They are similar to those of S. cerevisiae, except for TTA for leucine, and AAA for lysine. Codon Bias Index (CBI), a criterion to evaluate gene expression, is calculated from preferred codons. A computer program (PCBI) which reads a gene containing introns was developed to quickly calculate CBI. / Schw. occidentalis DWSS should be a good host to produce and secrete heterologous proteins and the putative preferred codons and program PCBI can facilitate molecular study of Schw. occidentalis. (Abstract shortened by UMI.)

The structure of one member of a family of maize mitochondrial RNA replicons (or RNA plasmids), RNA b, has been characterized. It is shown that RNA b shares a 13 nucleotide sequence with the central conserved region of Cadang-Cadang viroid of coconuts which might be involved in substrate recognition by the RNA replicase during replication. RNA b likely was derived from a larger member in that family, RNA a, through co-linear deletions similar to those involved with the generation of the defective interfering (DI) elements associated with both animal and plant viruses. RNA b may represent a "selfish" RNA optimized for replication as it does not have the capacity to encode its own replicase. Mitochondrial RNA plasmids have been found not to be restricted to the S and RU cytoplasms, as previously reported. Related plasmid RNAs have been detected in maize plants with C, N and T cytoplasms as well as 13 Latin American races. They were not found, however, in teosintes, indicating that the ancestral nucleic acid from which these RNAs evolved was acquired soon after the split between teosintes and maize, before the divergence of the maize races. Distribution of the plasmid RNAs, a maize mRNA (atp6), and a mitochondrial rRNA (26S) in different organs and tissues was investigated by in situ hybridization. These results indicated that mitochondrial gene expression is subjected to an unexpected degree of both spatial and developmental regulation, and that individual mitochondrial genes are subjected to different controls. Similar results were obtained in in situ hybridization studies of Brassica floral buds. Both studies suggested that the levels of mitochondrial genes transcripts are not particularly high in the tapetal cells of both maize and Brassica anthers contrary to common belief. High levels of RNA plasmid were detected in the pollen of S maize anthers prior to pollen abortion, suggesting they might be related to the cytoplasmic male sterility (CMS) trait of S maize

Dissertation (PhD)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (doktorgrades)--Christian-Albrechts-Universität zu Kiel, 1998. / Includes bibliographical references (p. [225-239) and index.

Thesis (B.S.) Magna Cum Laude--Butler University, 2008. / Includes bibliographical references (30-31).

Thesis (Ph. D.)--Oregon State University, 1991. / Includes mounted photographs. Typescript (photocopy). Includes bibliographical references (leaves 142-168). Also available on the World Wide Web.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

An Agrobacterium-mediated transformation system of purple raspberry ‘Amethyst’ was established after a series of experiments that determined the effect of genotype, inoculum density, and co-cultivation time on transformation. In this study, a plant regeneration protocol was established for ‘Joan J’ and ‘Polana’ (the regeneration protocol of ‘Amethyst’ was previously developed). Agrobacterium-mediated transformation was conducted for all three cultivars. The minimum killing level of hygromycin B and kanamycin was determined. Inoculum density and co-cultivation time were optimized. Polymerase chain reaction (PCR) verified a successful transformation of ‘Amethyst’ with the frequency of 3.3 ~ 4.4 % when leaves were infected with Agrobacterium EHA105 at the cell density of OD600 0.3 and co-cultivated for 3 days in the medium with 25.0 mg∙l-1 kanamycin. Transgenic lines with the PtFIT gene were hydroponically grown under iron sufficiency or deficiency. The real-time quantitative PCR verified the gene expression in response to iron sufficiency and deficiency conditions.

No description available.