Effect of CDC25 and WEE1 on Plant Cell Cycle and Morphogenesis

The cell cycle comprise the four phases of, G1, S-phase, G2 and mitosis. Two critical transitions are G1/S and G2/M; the latter is regulated by WEE1 kinase and CDC25 phosphatases. The scope of this thesis was to investigate the regulation of the G2/M transition of the cell cycle by WEE1 and CDC25, and how these genes interface with plant growth regulators in Arabidopsis thaliana. In Arabidopsis roots, the frequency of lateral roots was found to be increased by ectopic expression of Schizosaccharomyces pombe (Sp)cdc25e and reduced by Arath;WEE1 expression. I examined the effect of Arath;WEE1 and Spcdc25 on induction of shoots and roots in Arabidopsis hypocotyls in vitro. Hypocotyl explants from two over-expressing WEE1 lines , three T-DNA insertion lines and two expressing cdc25 (Spcdc25e) lines together with wild type (WT) were cultured on two-way gradients of kinetin (Kin) and naphthyl acetic acid (NAA). Below a threshold concentration of NAA (100 ng ml-1), WEE1 repressed morphogenesis in vitro, whereas at all NAA/Kin combinations Spcdc25 promoted morphogenesis (particularly root formation) over and above that in WT. Loss of function wee1-1 cultures were very similar to WT. Quantitative data indicated a significant increase in the frequency of root formation in Spcdc25e cultures compared with WT particularly at low Kin concentrations, and WEE1oe’s repressive effect was overcome by NAA but not Kin. In conclusion, WEE1 has a repressive effect on morphogenesis in vitro that can be overcome by auxin whereas Spcd25 by-passes a cytokinin requirement for the induction of morphogenesis in vitro. The role of CDC25 and WEE1 in DNA damage responses was also analysed. Two over-expressing Arath;CDC25 lines and T-DNA mutants showed no difference to WT either in standard conditions or zeocin-supplemented treatments. However, root length was longer in Arath;CDC25oe lines treated with hydroxyurea (HU) and lateral root number was increased compared to WT. This suggests a differential response of Arath;CDC25oe in the DNA replication (HU-induced) and DNA damage (zeocin-induced) checkpoints (Chapter 5). Finally the roles of WEE1 and CDC25 in cell cycle regulation were examined using tobacco TBY-2 cell cultures expressing Arath;WEE1, Nicotiana tabacum (Nicta)WEE1 or Arath;CDC25. Whilst Nicta;WEE1 lengthened G2 of the cell cycle, Arath;WEE1 had an unusual effect of shortening G2 phase and Arath;CDC25 had no observable effect (Chapter 6).

Ecology of the common octopus "Octopus vulgaris" (Cuvier, 1797) in the Atlantic Iberian coast : life cycle strategies under different oceanographic regimes

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultura), Universidade de Lisboa, Faculdade de Ciências, 2015

Complex Interplay Between Determinants of Pacing and Performance During 20 km Cycle Time Trials

Purpose This study examined the determinants of pacing strategy and performance during self paced maximal exercise. Methods Eight well trained cyclists completed two 20 km time trials. Power output, RPE, positive and negative affect, and iEMG activity of the active musculature were recorded every 0.5km, confidence in achieving pre-exercise goals was assessed every 5 km, and blood lactate and pH were measured post-exercise. Differences in all parameters were assessed between fastest (FAST) and slowest (SLOW) trials performed. Results Mean power output was significantly higher during the initial 90% of FAST, but not the final 10%, and blood lactate concentration was significantly higher and pH significantly lower following FAST. Mean iEMG activity was significantly higher throughout SLOW. RPE was similar throughout both trials, but participants had significantly more positive affect and less negative affect throughout FAST. Participants grew less confident in their ability to achieve their goals throughout SLOW. Conclusions The results suggest that affect may be the primary psychological regulator of pacing strategy and that higher levels of positivity and lower levels of negativity may have been associated with a more aggressive strategy during FAST. Although the exact mechanisms through which affect acts to influence performance are unclear, it may determine the degree of physiological disruption that can be tolerated, or be reflective of peripheral physiological status in relation to the still to be completed exercise task.

Life cycle assessment in the supply chain: a review and case study

The paper addresses the use of Life Cycle Assessment as a tool for analysing freight transport activity in product supply chains. Published works that have assessed freight transport energy use in supply chain operations are reviewed and their results summarized. A case study of the energy use in the supply chains for jeans sold in both the UK and France is presented. The results of this case study indicate that the location from which cotton is sourced can have a major impact on the total energy used in commercial transport in the jeans supply chain. However, overall, this has a limited impact on the total energy used in producing and supplying jeans. This is because the vast majority of total energy used in the supply chain is consumed during cotton cultivation, denim production and jeans manufacture. The work also demonstrates that the amount of energy used by consumers transporting jeans to their homes by car can be greater than the total commercial transport energy used in the supply chain (per kg of jeans transported).

Mental Toughness Moderates Social Loafing in Cycle Time-Trial Performance

Purpose: The purpose of this study was to determine if mental toughness moderated the occurrence of social loafing in cycle time-trial performance. Method: Twenty-seven men (Mage = 17.7 years, SD = 0.6) completed the Sport Mental Toughness Questionnaire prior to completing a 1-min cycling trial under 2 conditions: once with individual performance identified, and once in a group with individual performance not identified. Using a median split of the mental toughness index, participants were divided into high and low mental toughness groups. Cycling distance was compared using a 2 (trial) × 2 (high–low mental toughness) analysis of variance. We hypothesized that mentally tough participants would perform equally well under both conditions (i.e., no indication of social loafing) compared with low mentally tough participants, who would perform less well when their individual performance was not identifiable (i.e., demonstrating the anticipated social loafing effect). Results: The high mental toughness group demonstrated consistent performance across both conditions, while the low mental toughness group reduced their effort in the non-individually identifiable team condition. Conclusions: The results confirm that (a) clearly identifying individual effort/performance is an important situational variable that may impact team performance and (b) higher perceived mental toughness has the ability to negate the tendency to loaf.

The Asia Minor Greek adpositional cycle: a tale of multiple causation

This paper examines the interplay of language-internal continuity and external influence in the cyclical development of the Asia Minor Greek adpositional system. The Modern Greek dialects of Asia Minor inherited an adpositional system of the Late Medieval Greek type whereby secondary adpositions regularly combined with primary adpositions to encode spatial region. Secondary adpositions could originally precede simple adpositions ([PREPOSITION + PREPOSITION + NPACC]) or follow the adpositional complement ([PREPOSITION + NPACC + POSTPOSITION]). Asia Minor Greek replicated the structure of Ottoman Turkish postpositional phrases to resolve this variability, fixing the position of secondary adpositions after the complement and thus developing circumpositions of the type [PREPOSITION + NPACC + POSTPOSITION]. Later, some varieties dropped the primary preposition SE from circumpositional phrases, leaving (secondary) postpositions as the only overt relator ([NPACC + POSTPOSITION]) in some environments. In addition, a number of Turkish postpositions were borrowed wholesale, thus enriching the Greek adpositional inventory.

Comparison of allocation approaches in soybean biodiesel life cycle assessment

This work shows the influence of using different allocation approaches when modelling the inventory analysis in a soybean biodiesel life cycle assessment (LCA). Results obtained using mass, energy and economic based allocations are compared, focusing on the following aspects: normalised potential environmental impact (PEI) categories, total PEI and relative contributions to the total PEI from each life cycle stage and environmental impact category. Similar results are obtained either using economic and energy based allocations. However, different results are obtained when mass based allocation is used when compared with the other two. This study also illustrates that using different allocation approaches in biodiesel LCA may influence the final conclusions, especially in comparative assertions, emphasising the need to perform a sensitivity analysis in the LCA interpretation step.

Epigenetic and cell cycle control of centromere inheritance

Dissertation presented to obtain the Ph.D degree in Biology, Cell Biology

Tax policy stance over the business cycle: evidence from Europe

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics

Credit cycle identification: A Markov-switching application

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

Spore differentiation in relation to the infectious cycle of the enteric pathogen Clostridium difficile

Clostridium difficile is a gram positive, spore former, anaerobic bacterium that is able to cause infection and disease, with symptoms ranging from mild diarrhea to pseudomembranous colitis, toxic megacolon, sepsis and death. In the last decade new strains have emerged that caused outbreaks of increased disease severity and higher recurrence, morbidity and mortality rates, and C. difficile is now considered both a main nosocomial pathogen associated with antibiotic therapy as well as a major concern in the community.(...)

Nutritional plasticity and evolutionary divergence in the Drosophila ovary

The environment can modify developmental trajectories and generate a range of distinct phenotypes without altering an organism’s genome, a widespread phenomenon called developmental plasticity. The past decades have seen a resurgent interest in understanding how developmental plasticity contributes to evolutionary processes, as it can produce phenotypic variation among individuals and facilitate diversification among populations that inhabit distinct ecological niches. To better understand the importance of plastic responses for evolutionary change, we need to explore how the environment alters development to produce phenotypic variation and then compare this to how genetic variation influences these same developmental processes.(...)

Regarding to Implementation of Genetic Algorithmsin Life Cycle Management of Electrotechnical Equipment

Genetic algorithms regarding to life cycle management of electrotechnical equipment are considered. The concept of “techno-individual” is introduced.