Dysgenic male recombination (MR) induced by the P strains T-007 and OKI rarely, if ever, occurs in the heterochromatin of chromosome two. One possible explanation is that the lack of heterochromatic exchange is due to the highly condensed chromatin in this region. Butyrate (a suspected modifier of chromatin structure) induced significant levels of heterochromatic MR in dysgenic hybrids derived from crosses involving two different P strains. This finding is consistent with the hypothesis that chromatin structure can influence the insertion and excision of P elements and hence MR. Analogous experiments were performed using third chromosome suppressor of variegation (Su(var)) mutations. Neither suppressor mutation induced any heterochromatic MR, suggesting that the mode of action of these Su(var) genes is different from, and more specific than, that of butyrate. One of the mutations (325) which is thought to influence meiotic recombination frequencies, causes some alterations in euchromatic MR in crosses involving the OKI strain. The other mutation, 318, affects neither meiotic nor dysgenic recombination. Su(var) 325 is the first known "factor" to influence meiotic and dysgenic recombination similarly. / Science, Faculty of / Zoology, Department of / Graduate

Sequence analysis of tRNA 7 ser from Drosophila melanogaster was carried out, primarily by the formamide degradation and post-labeling method of Stanley and Vassilenko. Preliminary analysis was on the terminal nucleoside-5', 3'-bis [51 - ³²P] phosphates of electrophoretically separated [51 - ³²P] ribooligonucleotides, identifying the [³² P]-nucleotides by chromatography on PEI-cel1ulose plates. Further analysis of possible modified nucleotides was performed by thin layer chromatography of [5' -³²P] nucleoside phosphates derived by nuclease P-j digestion from [51 - ³²P] oligomers. The partial sequence generated in this fashion was supplemented by ladder gel sequence analysis of [51 - P]tRNA ser , and to a limited extent by two dimensional homochromatography. In this way, a sequence was obtained that is complete except for part of the aminoacyl stem and the 5'-end of the extra arm. The data are consistent with a sequence for tRNAser of pGCAGmUUGUGGCac4CGAGCGmGDDAAGGCXUCUGA— m3CUI GAi 6AAujCAGAUmUCCCUm3CUGGGAGm5CGUAGGTijjCGm1 AAUCCUACCGACUGCNCCA. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Unknown

Specific Drosphila tRNA Ser4,7 plasmids were identified and isolated by hybridization with purified [¹²⁵I] tRNA Ser4,7 molecules. Seven clones were isolated carrying the Drosphila Ser tRNA Ser4,7 gene and were further characterized by restriction endonuclease digestion; agarose gel electrophoresis and hybridization with individual purified [¹²⁵I] tRNA Ser4,7 molecules. The results show that five different DNA fragments have been isolated, four which code for a single, specific isoacceptor, and one which appears to code for two different isoacceptors. Two plasmids which initially contained multiple Hind III inserts upon primary isolation were recloned to contain single Hind III inserts containing the tRNA Ser4,7 gene. One of these recloned plasmids contained a smaller tRNA Ser4,7 gene carrying insert than did its original multiple insert isolate. Small tRNA Ser4,7 gene carrying restriction fragments were labelled with T4 polynucleotide kinase and [³²P] ATP, strand separated, and electroeluted, in preparation for nucleotide sequencing. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

The present study was initiated with the view of achieving two goals: 1) to establish a suitable genetic assay system for measuring the frequency of spontaneous and induced structural and numerical aberrations of autosomes during meiosis in females and 2) to provide a better understanding of the mechanisms responsible for the production of the aberrant classes recovered. By selective exclusion of all regular meiotic products this system enabled the recovery of large numbers of aberrant products. The multiplier system served as an internal dosimeter and provided an estimate of the population size from which the aberrancies arose which in turn provided a measure of the frequencies of each event. The four different classes of exceptional meiotic products were named according to the source or the structural nature of the chromosomes: reductional nondisjunction as "matroclinous"; equational nondisjunction as "equationals"; loss of chromosome 2 as "patroclinous"; and the attachment of homologous arms as "compounds". The results suggest that two main factors affect the recovery of induced aberrations: of most importance is isosequentiality and of lesser importance is genetic background. The three classes of simultaneously recovered progeny (excluding equational nondisjunctions) arise from a common mechanism of induction; a mechanism which also accounts for free arm formation. The location of the breaks, the position of the chromatids and the method of reconstitution determine the type of aberration produced. The reconstitution of these breaks in aberrant ways are referred to as interchanges. Furthermore, it would appear that the reconstitutions are restricted in that euchromatic breaks attach to euchromatic breaks and heterochromatic to heterochromatic. Interchanges resulting from breaks on opposite sides of the centromeres of homologues result in the formation of non-sister compound chromosomes and from breaks on opposite sides of the centromeres of sister chromatids result in the formation of sister compound chromosomes. The interchange, if between heterologues, could lead to the nondisjunction of a pair of chromosomes and be recovered, as in the present study, as matroclinous progeny. The reciprocal product of the interchange between heterologues would produce an equal number of nullo eggs observed as patroclinous progeny, but if the dyad so formed is heteromorphic, i.e. chromatids of different length, it would result in the greater recovery of patroclinous progeny because of the preferential inclusion of the shorter chromatid. The evidence for interchange mediated aberrations is provided by the recovery of free arms of chromosome 2. Experimental support for these events is provided by the unequivocal identification of the centromeres involved, which, as in this study, is made possible through the use of metacentric autosomes. / Science, Faculty of / Zoology, Department of / Graduate

Methionine sulfoxide reductase (MSR) is an important antioxidant to help mitigate oxidative stress that contributes to age-associated neurodegenerative diseases, such as Alzheimer’s Disease and Parkinson’s Disease. In MSR deficient Drosophila melanogaster (fruit flies), larvae show a developmental delay like that seen when wild-type larvae are reared on nutrient deficit culture medium. These investigators further showed that serotonin levels were depressed in these nutrient deficient larvae. The overarching aim of this study was to better understand the role of serotonin in MSR regulated physiology. Supplementing food with serotonin partially rescued the slower mouth hook movements (MHM) observed in the MSR-deficient flies. However, supplementation with serotonin altering drugs that cross the blood brain barrier (5-hydroxytryptophan, fluoxetine, or paravi chlorophenylalanine) did not rescue MHM and caused impairments to the growth of larvae during development. This study indicates that serotonin regulates feeding behavior partially through the regulation of MSR production but acts independently to regulate development. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Mitochondrial Complex I (CI) is composed of 44 distinct subunits that are assembled with eight Fe- S clusters and a single flavin mononucleotide. Mitochondria is highly enriched in the flight muscles of Drosophila melanogaster, however the assembly mechanism of Drosophila CI has not been described. We report that the mechanism of CI biogenesis in Drosophila flight muscles proceeds via the formation of ~315- , ~550-, and ~815 kDa CI assembly intermediates. Additionally, we define specific roles for several CI subunits in the assembly process. In particular, we show that dNDUFS5 is required for converting the ~700 kDa transient CI assembly intermediate into the ~815 kDa assembly intermediate, by stabilizing or promoting the incorporation of dNDUFA10 into the complex. Our findings highlight the potential values of Drosophila as a suitable model organism and resource to study the CI biogenesis in vivo, and to address questions relevant to CI biogenesis in humans. CI biogenesis is regulated by transient interactors known as CI assembly factors (CIAFs). To date, about half of CI disorders are attributed to the mutations in the CI subunits and the known CIAFs. The cause for the other half remains to be discovered, warranting the investigation for additional regulators of CI biogenesis such as novel CIAFs. To identify novel regulators, we cataloged interactors of a core subunit, NDUFS3, knocked each one down by RNAi in the Drosophila flight muscle, and analyzed its effect in the stability of CI by blue-native PAGE. We identified the Drosophila Fragile X Mental Retardation protein (dFMRP) to destabilize the holoenzyme of CI and cause it to misassemble. Therefore, we report dFMRP as a novel regulator of CI biogenesis, and demonstrate the utilization of Drosophila as an effective model system to uncover the mysteries of CI biogenesis.

No description available.

During development DNA-binding transcription factors are deployed downstream of patterning events to enable specific gene regulatory programs that define diverse cell identities. Within a given eukaryotic cell only a subset of potential binding targets in the genome, called cis-regulatory modules, are available due to the distribution of nucleosomes which restrict access to the underlying DNA. The accessible landscape of cells is highly dynamic over time and across different cell types, although how this process is regulated and influences the function of transcription factors in patterning of complex tissues is not well understood. In this thesis I focused on dissecting the cell type-specific chromatin accessibility landscapes that distinguishes different cell populations within the Drosophila dorsal appendages. The patterning of this system is extremely well characterized allowing for a detailed understanding of how transcription factors at the top of cell fate hierarchies influence, or respond to, the chromatin landscape during development. In Chapter 2 I describe the differences in chromatin accessibility along the proximal-distal axis of the wing imaginal disc which gives rise to distinct populations of the thoracic body wall and appendage in the second thoracic segment (T2). I found that a major driver of chromatin differences in these populations is the repressive input of the conserved insect wing marker Nubbin, whose function in the appendage is associated with decreasing accessibility of select chromatin regions relative to their conformation in body wall cells. In Chapter 3 I characterized the serially homologous body wall and appendage cells in the adjacent third thoracic body segment (T3), which diverge extensively in morphology from the T2 state due to influence of a single gene, Ultrabithorax (Ubx). Ubx is a member of the Hox gene family which functions to provide cells with spatial identity along the anterior-posterior axis. I show this function for Ubx in specifying T3 cells coincides with widespread changes to chromatin accessibility which contribute to a segment and cell type-specific regulatory program.

No description available.

No description available.