Search

Globally, Precambrian hydrocarbon systems are a new frontier, both from an academic and commercial perspective. In the São Francisco Basin of Brazil, a functioning Proterozoic hydrocarbon system occurs, yet the origins and the timing of its generation remain unknown. A basin-wide reconnaissance level study was approached to evaluate its hydrocarbon source potential and to determine its evolution from the Proterozoic inception, through to the present day. Three units were targeted in this study: the Meso/Neoproterozoic Canastra Group (Paracatú Formation), the Meso/Neoproterozoic Vazante Group (Serra do Garrote Formation) and the Cryogenian/Ediacaran Bambuí Group (Sete Lagoas Formation). The results indicate fair-good organic enrichment for the Paracatú and Serra do Garrote formations and almost null potential for the Sete Lagoas Formation in the location of study. Even with uncertainties, it is inferred that the three units are presently overmature, although it is not discounted that they were active generators in the past. New Re-Os dates for the Paracatú Slate Formation yields a depositional age of 1002±45 Ma, which is in agreement with published U-Pb detrital zircon age. Seismic interpretation, on the other hand, support an intracratonic setting for the deposition of the Bambuí Group and specifically for the Sete Lagoas Formation provides insights into restricted circulation associated to palaeotopography developed during the Jequitaí glaciation. Thermochronology dovetailed with analysis of porosity in borehole, reveal that significant post-Bambuí Group erosion has taken place. At least 3-6 km of strata is estimated to have been removed following the amalgamation of Gondwana. Maximum palaeotemperatures beneath this now missing cover were reached during the early Palaeozoic. Through basin modelling, it is shown that the Palaeozoic overburden allowed the Bambuí Group to enter the oil window. Hence, assuming adequate organic content in the strata, any hydrocarbons are predicted to have been generated during late Ediacaran to Cambrian times. This requires that the traps were already in place and hence long retention. For the older units, it can be argued that the São Francisco Basin has had the potential for hydrocarbon generation at least since Tonian times (i.e. ca. 1 Ga).

Psoriasis is an inflammatory skin disorder that is inherited as a common and complex trait. Linkage studies have repeatedly identified a primary disease susceptibility locus (PSORS1) spanning 250 kb within the Major Histocompatibility Complex. Deep sequencing experiments and genome-wide association scans have highlighted HLA-C as the most likely PSORS1 gene and unambiguously demonstrated that the HLA-Cw*0602 allele confers increased disease risk in a wide range of populations. In this context, the aim of this project was to investigate the impact of PSORS1 genetic variation on HLA-C transcription, with a particular focus on HLA-Cw*0602 expression. In the first part of the study, genetic variants mapping to the regulatory elements of different HLA-C alleles were characterized, by measuring the basal and cytokineinduced reporter activity driven by the HLA-Cw*0602, -Cw*0702 and -Cw*0304 promoters. These experiments identified two regulatory polymorphisms that virtually abolished the response to TNF-α (rs2524094) and IFN-γ (rs10657191) in HLA-Cw*0602 constructs. The existence of a differential cytokine response was also confirmed by the real-time PCR analysis of primary keratinocytes treated with TNF-α and IFN-γ. Since little is known about the role of epigenetic factors in the regulation of HLA-C expression, the presence of HLA-Cw*0602 specific modification patterns was examined in the second part of the project. The methylation status of the five PSORS1 CpG islands (CGIs) was initially investigated. This targeted approach revealed lack of methylation at four CGIs, two of which mapped within the HLA-C gene region. Partial methylation was detected at a fifth CGI, lying upstream of POU5F1. To complement these data, a methylation profile of the entire PSORS1 locus was generated in two HLA Cw*0602,-Cw*0702 heterozygous individuals. This showed that the majority of methylated cytosines mapped between the POU5F1 and C6orf15 transcripts, and upstream of HLA-C. Neither the targeted CGI analysis nor the systematic profiling of the entire PSORS1 region revealed any substantial differences in the methylation status of haplotypes bearing different HLA-C alleles. Taken together, the results of this study indicate that HLA-C expression is tightly controlled by promoter variants and immunological stimuli. Further studies will be required to fully explore the impact of genetic variation on DNA methylation and to determine whether PSORS1 epigenetic modifications play a role in psoriasis susceptibility.

This thesis uses industry seismic (3D and 2D) and well data to investigate the depositional and deformational processes of the Messinian evaporites in the Levant Basin, Eastern Mediterranean. Detailed interpretation of the geometry, structural and stratigraphic context of the evaporites has been undertaken in order to improve our understanding of the events occurring during the Messinian Salinity Crisis in the region. The Messinian evaporites form a wedge up to 1.8km thick that pinches out towards the continental margin, where they pass laterally to a prominent erosional surface. The 3D seismic data have allowed the complete basinal evaporitic series to be imaged in three dimensions for the first time. Investigations showed that clastic bodies and focused incisional pattern developed at their base. The internal part of the evaporites is composed of parallel and continuous seismic reflections, alternating with transparent seismic facies. These internal reflections are truncated at the top of the Messinian evaporites, against a widespread erosional unconformity. The analysis of the 2D seismic data permitted the connection of these morphological features with a regional system of canyons, developed on the Levant continental margin since the Oligocene. The canyons acted during the Messinian Salinity Crisis as clastic fairways, erosional loci and depocentres for the evaporites. The morpho-structural observations collected have been compared to the pre- and post-evaporitic setting, in order to infer the depositional environment and post-depositional behaviour of the evaporites. Relative sea-level changes in the basin have been interpreted in relation with two major erosional events developed at the base and at the top of the evaporites. Finally, the three-dimensional analysis also allowed an early (Messinian) stage of deformation of the evaporites to be identified, and the discovery of the occurrence of evaporite dissolution during the Pliocene.

This dissertation is an investigation into how plants provide a way to explore cultural interactions between Greece and Rome and the east. I use India, a region that remained consistently exotic to most Greeks and Romans throughout antiquity, as a test case to examine how eastern plants were received and integrated into Greek and Roman culture. Throughout I use my test case as a focus and as an object of comparison: India is a constant reminder of what was conceptualized as exotic. My methodology is primarily "plants in text," an approach that incorporates both the physical reality of plants for sale at the market as well as the imagined flora that grows at the end of the earth. The results of this inquiry show the value of investigating the cultural importance of plants and the mental constructs that surround them in the ancient Greek and Roman worlds., The Classics