Investigation of the role of long non-coding RNAs in oncogene induced cellular senescence

Cellular senescence is a stable arrest of cell proliferation induced by several factors such as activated oncogenes, oxidative stress and shortening of telomeres. Senescence acts as a tumour suppression mechanism to halt the progression of cancer. However, senescence may also impact negatively upon tissue regeneration, thus contributing to the effects of ageing. The eukaryotic genome is controlled by various modes of transcriptional and translational regulation. Focus has therefore centred on the role of long non- coding RNAs (lncRNAs) in regulating the genome. Accordingly, understanding how lncRNAs function to regulate the senescent genome is integral to improving our knowledge and understanding of tumour suppression and ageing. Within this study, I set out to investigate the expression of lncRNAs’ expression within models of senescence. Through a custom expression array, I have shown that expression of multiple different lncRNAs is up-regulated and down regulated in IMR90 replicative senescent fibroblasts and oncogene-induced senescent melanocytes. LncRNA expression was determined to be specific to stable senescence-associated cell arrest and predominantly within the nucleus of senescent cells. In order to examine the function of lncRNA expression in senescence, I selected lncRNA transcript ENST0000430998 (lncRNA_98) to focus my investigations upon. LncRNA_98 was robustly upregulated within multiple models of senescence and efficiently depleted using anti-sense oligonucleotide technology. Characterisation and unbiased RNA-sequencing of lncRNA_98 deficient senescent cells highlighted a list of genes that are regulated by lncRNA_98 expression in senescent cells and may regulate aspects of the senescence program. Specifically, the formation of SAHF was impeded upon depletion of lncRNA_98 expression and levels of total pRB protein expression severely decreased. Validation and recapitulation of consequences of pRB depletion was confirmed through lncRNA_98 knock-out cells generated using CRISPR technology. Surprisingly, inhibition of ATM kinase functions permitted the restoration of pRB protein levels within lncRNA_98 deficient cells. I propose that lncRNA_98 antagonizes the ability of ATM kinase to downregulate pRB expression at a post-transcriptional level, thereby potentiating senescence. Furthermore, lncRNA expression was detected within fibroblasts of old individuals and visualised within senescent melanocytes in human benign nevi, a barrier to melanoma progression. Conversely, mining of 337 TCGA primary melanoma data sets highlighted that the lncRNA_98 gene and its expression was lost from a significant proportion of melanoma samples, consistent with lncRNA_98 having a tumour suppressor functions. The data presented in this study illustrates that lncRNA_98 expression has a regulatory role over pRB expression in senescence and may regulate aspects of tumourigenesis and ageing.

The development of the accounting professional in a postcolonial context: evidence from Sierra Leone

Despite increasing interest in the development of the accountancy profession and constitutive professional bodies in ex-colonies, little is known about the development of professional accountants as individuals. Similarly, although the continuing influence of the legacies of colonialism and imperialism on the accounting professionalisation trajectory in ex-colonies has been recognised, little attempt has been made to theorise such continuing colonial intervention as a postcolonial condition of accommodation and resistance, with implications for the development of professional accountants. This thesis fills this vacuum by employing four aspects of the critical lens of postcolonial theory – local-global nexus, psycho-existential complex, postcolonial hybridity and diaspora - to gain an insight into the development of accounting professionals in ex-colonies with specific reference to Sierra Leone. Specifically, it examines the current model of accounting professionalisation adopted in Sierra Leone and implications for the development of professional accountants in the country; investigates the historical and ideological legacies of colonialism that shaped and continue to influence the professionalisation trajectory in Sierra Leone; explores the perceptions of Sierra Leonean chartered and aspiring accountants of their professional identity in terms of their professional development within Sierra Leone; and explores the lived experiences of Sierra Leonean chartered and aspiring accountants in the diaspora and the diaspora effect on accountancy in Sierra Leone. The empirical evidence presented here emanated from two sources: a web-based survey and semi-structured interviews with Sierra Leonean chartered and aspiring accountants both within and outside the country at the time of the study. The model for developing professional accountants in Sierra Leone comprises a partnership between the local professional body, ICASL, and the British-based global body, the ACCA. A postcolonial analysis of the empirical evidence reveals that an unintended consequence of this model is that the local is co-opted within the global while the global becomes increasingly localised. The analysis also shows that the presence of a perceived global body ‘inferiorises’ the local body to the point of undesirability among local chartered and aspiring accountants. Thus the partnership has to date done little by way of developing ICASL’s capacity to ensure the development of a localised profession and professionals. Instead, it produces, within the Sierra Leone accountancy space, professional hybrids that at once pose as global as well as local accountants. This has significant implications for the local profession because many of the hybrid professional accountants who could potentially drive the local profession forward end up in the diaspora, which leaves the local profession in a weaker state. Also, given the established link between a robust accountancy profession and sustainable economic development, such professional diasporisation could negatively impact on the country’s economic development. In sum, Sierra Leone has failed to establish an accounting professionalisation model that develops professional accountants (through contextualised professional education and training) that meets the specific accounting needs of its growing economy.

Aspects of the biology of Lutraria lutraria (L.) (bivalvia : Mactracea)

The life history of a population of Lutraria lutraria in a depth of 7m at Hunterston, Ayrshire is discussed. Much of the present population Is thought to have settled in 1967. The functional morphology of Lutraria is described and related to its life as a large, deep-burrowing bivalve. Lutraria spawned in late spring and continued to do so through the summer in 1979 and 1980. Animals became spent in August and September. Unsuccessful attempts were made to induce spawning in the laboratory. Artificial fertilization was successful but development did not proceed beyond the ciliated gastrula stage. Larvae of Lutraria were not identified in plankton samples and young stages were not encountered in sieved sediment samples. The biochemical cycle of the total animal and five component parts (gonad and visceral mass, digestive gland, adductor muscle, siphon and 'other' tissue) is investigated. A marked increase in weight, reflected in an increase in weight of the component parts, was recorded in Autumn 1979. This is thought to be related to an exceptional increase in the phytoplankton at this time. Although a relationship between the biochemical cycle and reproductive cycle remains uncertain, definite seasonal changes were recorded in the respiration rate of Lutraria. At 10°C, the maximum rate of a standard 20g animal was 0.1283m1s 02/g. dry wt./hr. in May 1980 and the minimum rate was 0.O59mls 02/g. dry wt./hr. in October 1980. The effect of temperature on respiration rate was also investigated. Significant differences were recorded for five experimental temperatures (10°C, 15°C, 20°C, 25°C and 30 °C) in August and October but only between two temperatures (10 C and 30 C) in April. There was a decrease in respiration rate at 30 C in August and October, but an increase in April. Respiration rate is affected by a reduction in oxygen tension. A variety of responses were recorded with a small degree of regulation shown. Individuals of Lutraria were able to survive 48 hours under anaerobic conditions. In fully oxygenated conditions heart rate ranged from 4-15 beats per minute with an average of 8 beats per minute. Heart beat was markedly affected by changes in temperature and oxygen tension, increasing to a maximum 22 beats per minute at 25 C, and decreasing to a minimum 2 beats per minute in anaerobic conditions. Heart rate is reduced (12 beats per minute to 5 beats per minute) on exposure to air. Lutraria exhibits an intermittent pattern of pumping activity. Under normal conditions 35% of the time is spent pumping and this Increases as oxygen is reduced (3.00mls 02/litre) to 65% of the time spent pumping. 15. Under normal conditions the respiratory flow varies between 0.382 litres per hour and 1.023 litres per hxir. Adult Lutraria maintain their ability to burrow, albeit slowly.