The quest for golden bananas: Investigating carotenoid regulation in a Fe’i group Musa cultivar

The regulation of carotenoid biosynthesis in a high-carotenoid-accumulating Fe’i group Musa cultivar, “Asupina”, has been examined and compared to that of a low-carotenoid-accumulating cultivar, “Cavendish”, to understand the molecular basis underlying carotenogenesis during banana fruit development. Comparisons in the accumulation of carotenoid species, expression of isoprenoid genes, and product sequestration are reported. Key differences between the cultivars include greater carotenoid cleavage dioxygenase 4 (CCD4) expression in “Cavendish” and the conversion of amyloplasts to chromoplasts during fruit ripening in “Asupina”. Chromoplast development coincided with a reduction in dry matter content and fruit firmness. Chromoplasts were not observed in “Cavendish” fruits. Such information should provide important insights for future developments in the biofortification and breeding of banana.

Mitochondrial helicase Twinkle in mtDNA copy number regulation and a late-onset disease model

Mitochondrial diseases are caused by disturbances of the energy metabolism. The disorders range from severe childhood neurological diseases to muscle diseases of adults. Recently, mitochondrial dysfunction has also been found in Parkinson s disease, diabetes, certain types of cancer and premature aging. Mitochondria are the power plants of the cell but they also participate in the regulation of cell growth, signaling and cell death. Mitochondria have their own genetic material, mtDNA, which contains the genetic instructions for cellular respiration. Single cell may host thousands of mitochondria and several mtDNA molecules may reside inside single mitochondrion. All proteins needed for mtDNA maintenance are, however, encoded by the nuclear genome, and therefore, mutations of the corresponding genes can also cause mitochondrial disease. We have here studied the function of mitochondrial helicase Twinkle. Our research group has previously identified nuclear Twinkle gene mutations underlying an inherited adult-onset disorder, progressive external ophthalmoplegia (PEO). Characteristic for the PEO disease is the accumulation of multiple mtDNA deletions in tissues such as the muscle and brain. In this study, we have shown that Twinkle helicase is essential for mtDNA maintenance and that it is capable of regulating mtDNA copy number. Our results support the role of Twinkle as the mtDNA replication helicase. No cure is available for mitochondrial disease. Good disease models are needed for studies of the cause of disease and its progression and for treatment trials. Such disease model, which replicates the key features of the PEO disease, has been generated in this study. The model allows for careful inspection of how Twinkle mutations lead to mtDNA deletions and further causes the PEO disease. This model will be utilized in a range of studies addressing the delay of the disease onset and progression and in subsequent treatment trials. In conclusion, in this thesis fundamental knowledge of the function of the mitochondrial helicase Twinkle was gained. In addition, the first model for adult-onset mitochondrial disease was generated.

Thrombin regulation in newborn infants

The coagulation system of newborn infants differs markedly from that of older children and adults. The activities of most coagulation factors and anticoagulants are low, leading to altered regulation in the formation of the key enzyme, thrombin. Timely and adequate generation of thrombin is essential, as thrombin activates platelets and many coagulation factors, cleaves fibrinogen into fibrin and activates the antithrombotic and anti-inflammatory protein C pathway. On the other hand, excess thrombin may promote thrombotic complications and exacerbate harmful inflammatory reactions. Despite the characteristic features, the newborn coagulation system can be considered physiological, since healthy newborns rarely show haemorrhagic or thrombotic complications. Sick newborns, however, often encounter clinical situations that challenge their coagulation system. The aim of this study was to clarify the behaviour of the neonatal coagulation system in selected clinical situations, with a special emphasis on the generation of thrombin. Thrombin was measured by in vivo thrombin generation markers and by thrombin generation potential in vitro. The patient groups included sick newborns undergoing intensive care and receiving fresh-frozen plasma (FFP), requiring exchange transfusions (ET) or presenting with a congenital heart defect requiring open heart surgery. Additionally, healthy newborns with inherited heterozygous factor V Leiden (FVL) mutation were studied. Thrombin generation potential was also analysed in cord plasma of healthy infants and in adults. Healthy as well as sick newborn infants showed lower total thrombin generation potential in vitro but faster initiation of thrombin generation than adults. These findings were qualitatively similar when plasma was supplemented with platelets. Platelets, however, significantly altered the effect of the major anticoagulant, activated protein C (APC), on thrombin generation potential. In accordance with previous studies, thrombin generation in healthy newborn platelet-poor plasma was resistant to the anticoagulant effects of APC, but when the plasma was supplemented with platelets APC attenuated thrombin generation significantly more in newborns than in adults. In vivo generation of thrombin was elevated in nearly all of the sick newborn infants. The low-volume FFP transfusion as opposed to the change from neonatal to adult blood in ET exerted markedly different effects on neonatal thrombin generation. FFP reduced the in vivo generation of thrombin in those newborns with the highest pretransfusional thrombin generation, thus acting as an anticoagulant agent. In those infants with lower pretransfusional thrombin generation, the effect of FFP on thrombin generation was fairly neutral. On the other hand, the combination of red blood cells and FFP, used to perform ET, significantly increased the in vivo thrombin formation and shifted the balance in the newborn coagulation system to the procoagulant direction. Cardiopulmonary bypass (CPB) also significantly increased the in vivo thrombin generation, but the thrombin generation profile during CPB differed from that previously observed in adults. Escalation of thrombin at early reperfusion was not observed in newborns; in adults, its occurrence is associated with postoperative myocardial damage. Finally, in healthy newborns with FVL heterozygosity, faster initiation of thrombin generation was observed compared with controls. Interestingly, FV level was lower in FVL-heterozygous infants, possibly to counteract the procoagulant effects induced by FVL. In conclusion, unique features regarding thrombin regulation in newborn infants were observed. These features included a novel platelet effect on the regulation of the protein C pathway. The clinical challenges mainly seemed to shift the balance in the coagulation system of newborns to the procoagulant direction. Blood component transfusions markedly affected coagulation in a manner specific to the product but that could also be altered by the clinical situation. Overall, the results highlight the need for understanding developmental haemostasis for both diagnostic and therapeutic purposes.

Consumer’s comparison between local and imported organic products: A hedonic analysis of the Japanese table wine market

Although hundreds of thousands of organic products are traded on a daily basis, it is less known how imported organic products are evaluated by consumers in an importing country. The paper analyzes Japanese wine point of sale (POS) data to examine whether consumers differentiate between local and imported organic products. The results of our hedonic analyses show that the premium for imported organic red (white) wines is about 42.996 % (8.872 %) while that for domestic red (white) organic wines is about 6.440 % (1.214 %), implying that Japanese consumers pay higher premiums for imported organic agricultural products than for those produced in Japan.

The channels of monetary policy triggered by central bank actions and statements in the Australian equity market

Owing to the discrete disclosure practices of the Reserve Bank of Australia, this paper provides new evidence on the channels of monetary policy triggered by central bank actions (monetary policy announcements) and statements (explanatory minutes releases), in the Australian equity market. Both monetary policy announcements and explanatory minutes releases are shown to have a significant and comparable impact on the returns and volatility of the Australian equity market. Further, distinct from US and European studies that find strong evidence of the interest rate, bank loan and balance sheet channels and no evidence of the exchange rate channel following central bank actions, this paper finds that monetary policy impacts the Australian equity market via the exchange rate, interest rate and bank loan channels of monetary policy, with only weak evidence of the balance sheet channel of monetary policy. These channels are found to be operating irrespective of the trigger (monetary policy announcements or explanatory minutes releases), though results are somewhat weaker when examining the explanatory minutes releases. These results have important implications for central bank officials and financial market participants alike: by confirming a comparable avenue to affect monetary policy; and providing an explication of its impact on the Australian equity market.

Regulation of Reproduction in the Primitively Eusocial Wasp Ropalidia marginata: on the Trail of the Queen Pheromone

Queens and workers are not morphologically differentiated in the primitively eusocial wasp, Ropalidia marginata. Upon removal of the queen, one of the workers becomes extremely aggressive, but immediately drops her aggression if the queen is returned. If the queen is not returned, this hyper-aggressive individual, the potential queen (PQ), will develop her ovaries, lose her hyper-aggression, and become the next colony queen. Because of the non-aggressive nature of the queen, and because the PQ loses her aggression by the time she starts laying eggs, we hypothesized that regulation of worker reproduction in R marginata is mediated by pheromones rather than by physical aggression. Based on the immediate loss of aggression by the PQ upon return of the queen, we developed a bioassay to test whether the queen's Dufour's gland is, at least, one of the sources of the queen pheromone. Macerates of the queen's Dufour's gland, but not that of the worker's Dufour's gland, mimic the queen in making the PQ decrease her aggression. We also correctly distinguished queens and workers of R. marginata nests by a discriminant function analysis based on the chemical composition of their respective Dufour's glands.

Action regulation across the adult lifespan (ARAL): A metatheory of work and aging

The goals of this article are to integrate action regulation theory (ART) with the lifespan developmental perspective and to outline tenets of a new metatheory of work and aging. The action regulation across the adult lifespan (ARAL) theory explains how workers influence, and are influenced by, their environment across different time spans. First, the basic concepts of ART are described, including the sequential and hierarchical structure of actions, complete tasks and actions, foci of action regulation, and the action-regulating mental model. Second, principles of the lifespan developmental perspective are delineated, including development as a lifelong and multidirectional process, the joint occurrence of gains and losses, intraindividual plasticity, historical embeddedness, and contextualism. Third, propositions of ARAL theory are derived by analyzing workers’ action regulation from a lifespan developmental perspective (i.e., effects of aging on action regulation), and by analyzing aging and development in the work context from an ART perspective (i.e., effects of action regulation on age-related changes in cognition and personality). Fourth, we develop further propositions to integrate ART with lifespan theories of motivation and socioemotional experience. Finally, we discuss implications for future research and practice based on ARAL theory.