Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 13).

Conditional lethals which survive under "permissive" conditions but die under "restrictive" conditions have greatly facilitated genetic and biochemical analyses in micro-organisms. One class of conditional lethals, the so-called temperature-sensitives, has been recovered from ethyl methanesulfonate-induced lethals in Drosophila melanogaster. Such mutants survive at 17°C or 22°C but die at 29°C and appear to map genetically as point mutants. These mutants may be useful in identifying previously undetected loci and in studying mitotic, meiotic and developmental processes. In Drosophila gross developmental studies indicate that recessive temperature-sensitive (ts) lethals may have specific developmental effects. By means of shifting different cultures from one temperature to the other at successive intervals, the period during which the restrictive temperature (29°C) prevented survival could be ascertained. Each ts lethal could be classified with respect to its effective lethal phase(s), its period(s) of temperature-sensitivity and any effect on visible morphological characteristics. Four sex-linked recessive ts lethals were studied extensively with respect to their genetic and developmental action. Each of these mutants is representative of a different class of lethals with specific properties: pupal lethality, indispensability, sexual dimorphism, and parental influence. The potential use of these and other ts lethals in genetic and developmental analyses is discussed. / Science, Faculty of / Zoology, Department of / Graduate

Reported here is the isolation and molecular characterization of two novel alleles of the DIP 1 gene; GE89 and GE77. As well, a third deletion of the DIP 1 gene, EY*4, isolated by our collaborators in France was characterized. PCR and sequencing analysis confirms all three alleles to be molecular deletions of the DIP 1 gene. However, in none of these cases is the entire gene excised. Also, immunohistochemistry of ovaries from each of these strains does not demonstrate a complete lack of DIPl protein expression in any of the deletion strains. Thus, it appears that some protein product is being formed in each case. However, it is not clear whether this protein is functional. An assay was also conducted to investigate a function for DIPl in mechanisms of epigenetic gene silencing. Although the findings of these experiments are incomplete, it appears that DIPl may play a functional role in heterochromatin formation and/or post-transcriptional gene silencing. Interestingly, appendage formation phenotypes were observed in the original P-element insertion line as well as a female sterility phenotype in the GE77 allele. Overall, DIP 1 is an interesting double stranded RNA binding protein. Newly isolated alleles of the DIP 1 gene will be useful tools for further investigation of the functional role of this gene. / Thesis / Master of Science (MSc)

Malpighian (renal) tubules of the fruit fly Drosophila melanogaster consist of three functional domains: a non-secretory distal segment, a secretory main segment and a reabsorptive lower segment. In this study a computer-controlled micropositioning system and a self-referencing K^+ microelectrode were used to measure K^+ concentration gradients of extracellular unstirred layers associated with specific epithelial domains. K^+ fluxes were calculated from the measured gradients. This is the first time: that an accurate assessment of the concentration gradients of the unstirred layer of Drosophila melanogaster could be assessed due to the enhanced sensitivity of this self-referencing technique over conventional ion-selective microelectrodes. The technique permits high resolution spatial and temporal mapping of the flux patterns in response to stimulation or inhibition of ion transport. Variations in K^+ transport over time and at different sites suggest that transport is non-uniform within any one functional domain. / Thesis / Master of Science (MSc)