The biosynthesis of terpenoids in tissue culture: Syntheses of lethal metabolites and toxicity studies

The work described can be conveniently divided into four related but distinct sections. Part One describes a set of experiments that follow on from a previous study of the incorporation of 1-14C-Isopentenyl pyrophosphate (1-14C-IPP) into terpenoids by cell-free extracts from cultures of Lavandula angustifolia. Of the total incorporations (ca. 5%) most (70%) of the label was present in the farnesols. The addition of NADP caused an increase of incorporation into the sesquiterpenoid hydrocarbons caryophyllene (13%) and humulene (30%), with a concomitant decrease of incorporation into the farnesols. By using enriched cell-fractions the site of sesquiterpenoid biosynthesis was found to be associated with the microsomal fraction. Part Two describes a series of experiments carried out on cell-suspension cultures of Pelargonium fragrans. A statistically reliable and novel method of estimating cell-viability was developed to study the toxicities of some common terpenoids as such toxicity may account for the lack of accumulation of terpenoids in culture. All compounds were toxic (in the range 1-5 mmol.dm-3) and the toxicity (LD50) was greatest during the exponential-period of culture-growth. The cultures could however, be habituated to the terpenoids over a number of subcultures. The inclusion of a surfactant in the culture-medium lowered the toxicity of the terpenoids and therefore provided a model storage mechanism (sink) for these compounds in a single-phase culture. The polyethoxylate-surfactants were found to be the most suitable for this purpose. Two subsidiary studies deal with the toxicity of some fluorinated compounds to tissue cultures and the reactions of exogenous terpenoids with the culture medium. Part Three describes the syntheses of five fluorinated monoterpenoids. Two fluorinated linalools (4-fluoro- and 9-fluoro-) were prepared by treatment of the respective fluoro-6-methyl-hept-5-en-2-ones with vinylmagnesium bromide. A number of methods of introducing fluorine into 6-methyl-hept-5-en-2-one were attempted; the most successful method involved fluorination of the trimethylsilyl-enol ethers using N-fluoro-pyridinium triflate. Linaloyl, neryl and geranyl fluorides were prepared by treatment of the corresponding chlorides with anhydrous tetrabutylammonium bifluoride. 19F-, 1H- and 13C-nuclear magnetic resonance and mass spectrometry were used to characterise the products. Some unexpected results are discussed in detail. Part Four describes studies that were used to interpret the fragmentation patterns in the mass spectra of three monoterpenoid acetates occurring in the oil of L. angustifolia that was studied in Part One. Linaloyl, neryl and geranyl acetates all showed identical electron-impact mass spectra. A combination of linked-scanning and deuterium-labelling experiments were used in order to characterise the fragmentation patterns. Other methods of ionisation (fast atom bombardment and chemical ionisation in the positive and negative modes) were also used to confirm the patterns

Estrogen and progestin content in the peripheral plasma and follicular fluid of cycling beef cattle

The objectives of this experiment are as follows: (1) to compare estrogen and progestin levels in the peripheral circulation to steroid levels in the follicular fluid, (2) to compare estrogen and progestin levels within small, medium, and large follicles, and (3) to obtain estrous dates along with morphological ovarian descriptions to use as a basis for the aforementioned comparisons. There were 180 Hereford heifers (6 per pen) used in this experi-ment. The animals were slaughtered when the mean thickness of backfat for the animals in a pen (6 per pen) reached 12 mm as measured by the somascope. Blood and follicular fluid were sampled and assayed simul-taneously for estrogen and progestin content using radioimmunoassay. Ovarian weights, corpus luteum weights, and follicle numbers were also recorded. Prior to slaughter, all heifers had been observed for estrous acitivities; and following slaughter, each pair of ovaries were classi-fied as to stage of growth (MGU) and inspected for abnormalities. Progestins and estrogens varied inversely throughout the MGU growth phases, and their patterns, levels, and ranges compared favorably with those previously described in the literature. Only progestin from medium follicles had secretion patterns similar to patterns in the plasma. There were significant differences (P\u3c.001) in estrogen and progestin levels and patterns from different size follicles. Progestins varied significantly among MGU; however, estrogen was quite variable and showed no statistically significant relationship to MGU. Within size categories, steroid concentrations in the follicular fluid varied independently of volume changes. Follicle numbers per pair of ovaries remained constant for large follicles (one follicle per pair of ovaries) but varied within the small (12-100) and medium (1-6) classification. Morphological ovarian descriptions (MGU) were used as a basis for comparisons of estrogen and progestin levels in the peripheral circulation with steroid levels in follicular fluid and for comparisons between follicle sizes. Behavioral estrous cycles were extremely variable with 27 percent having short cycles (\u3c15 days) and 37 percent having long cycles (\u3e26 days). Approximately 50 percent of the animals were observed in standing estrus while the other half were not observed standing, but did display a color change in the KaMar Heatmount Detector. Within the MGU classifications, there was a disproportionality in numbers of heifers in MGU V and VI. This suggests that prior to and at the beginning of regression are the most variable stages in the corpus luteum morphology, thus emphasizing an explanation for variability in the cycle lengths that was observed in the heifer experiment

Is there a male victim?: Discursive subjection in representations of female-on-male childhood sexual abuse

This thesis investigates established theoretical and embodied accounts of identities excluded within Western heteronormative society in order to seek out how those embodiments and theories may parallel what is contended that another impossible subject position -- the child male victim of adult female sexual violence

Highly Siderophile Element and Tungsten Systematics of Hawaiian Picrites

A suite of Hawaiian picrites (MgO > 13 wt.%), and associated basalts, that represent some of the most primitive melts from the Hawaiian mantle source regions were analyzed for their W, highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd and Re) and 186Os-187Os isotope systematics. These picritic samples are among the most primitive samples produced from the Hawaiian main-shield stage volcanoes. As such, they may preserve considerable information about the mantle source regions from which they were derived. Hawaii is of particular interest because there is geochemical and geophysical evidence that suggest that the Hawaiian plume may originate at the core-mantle boundary. If any outer core material is incorporated into plume lavas, it could carry important geochemical information. The primary goal of this study is to improve our understanding of the processes and materials that may affect the mantle source regions of the Hawaiian volcanoes. Abundances of HSE and W, as well as Os isotopes, are useful tools for evaluating the mantle source regions of ocean island basalts because their absolute and relative abundances may be affected by various mantle processes, including the recycling of oceanic crust and sediment, mantle metasomatism, and other forms of crystal-liquid fractionation. In addition, these elements may be suitable for addressing the question of core-mantle interaction, because the core is highly concentrated in both the moderately siderophile and highly siderophile elements, and may have a distinct Os isotopic composition relative to the mantle. The collected data imply that W abundances in the Hawaiian mantle sources are similar for all volcanic centers, and enriched relative to depleted MORB mantle. This suggests that W may be controlled by a primary source component that is less depleted in incompatible elements than the depleted mantle. HSE abundances in the picrites are controlled predominantly by crystal-liquid fractionation processes, and may reflect the presence of residual sulfides in the mantle sources. Lastly, the 187Os/188Os variations are consistent with some proportion of a recycled oceanic crust component; however, variations in 186Os/188Os require another process, such as the incorporation of variable Pt-enriched base-metal sulfides, or mixing with an 186Os-187Os enriched reservoir

Mapping the Shores of the Brown Dwarf Desert. I. Upper Scorpius

We present the results of a survey for stellar and substellar companions to 82 young stars in the nearby OB association Upper Scorpius. This survey used nonredundant aperture mask interferometry to achieve typical contrast limits of ΔK ~5-6 at the diffraction limit, revealing 12 new binary companions that lay below the detection limits of traditional high-resolution imaging; we also summarize a complementary snapshot imaging survey that discovered seven directly resolved companions. The overall frequency of binary companions (~35 +5 -4% at separations of 6-435 AU) appears to be equivalent to field stars of similar mass, but companions could be more common among lower mass stars than for the field. The companion mass function has statistically significant differences compared to several suggested mass functions for the field, and we suggest an alternate lognormal parameterization of the mass function. Our survey limits encompass the entire brown dwarf mass range, but we only detected a single companion that might be a brown dwarf; this deficit resembles the so-called brown dwarf desert that has been observed by radial velocity planet searches. Finally, our survey’s deep detection limits extend into the top of the planetary mass function, reaching 8-12 MJup for half of our sample. We have not identified any planetary companions at high confidence (≳99.5%), but we have identified four candidate companions at lower confidence (≳97.5%) that merit additional follow-up to confirm or disprove their existence

Transitioning to University: A Sober Experience

This study was designed to investigate the experiences of non-drinking, first year undergraduate students during their transition to university life. To achieve this, six semi-structured interviews were conducted. Upon transcription the interviews, each was analysed using thematic analysis (Braun and Clarke, 2006). From the analysis, four themes were identified: ‘Experiencing pressure to drink’, ‘making excuses not to drink’, ‘sports societal exclusion’ and ‘a gradually improving experience: ‘it gets easier with time’’. The analysis revealed an overall difficult experience for each non-drinking participant, aligning with and in some cases building upon the previous literature, suggesting the importance of alcohol amongst the student population, especially during the initial transitional period. Throughout each interview and imbedded in each theme was an overarching presence of social identity, defining for each participant both their own and their peers places as first year university students. As this study and others like it are aiding in illuminating the potential struggles of non-drinking, first year students during the transition to University, results could help in tailoring university support to the students in need

The lengths of Hermitian Self-Dual Extended Duadic Codes

Duadic codes are a class of cyclic codes that generalizes quadratic residue codes from prime to composite lengths. For every prime power q, we characterize the integers n such that over the finite field with q^2 elements there is a duadic code of length n having an Hermitian self-dual parity-check extension. We derive using analytic number theory asymptotic estimates for the number of such n as well as for the number of lengths for which duadic codes exist.Comment: To appear in the Journal of Pure and Applied Algebra. 21 pages and 1 Table. Corollary 4.9 and Theorem 5.8 have been added. Some small changes have been mad