Quantitative histochemistry was used to investigate the tissue-specific compartmentation of soluble carbohydrates (sucrose, glucose, fructose), starch and malate in the laminar pulvinus, leaf blade and petiole of Phaselous coccineus L. at day and night positions of diurnal leaf movement. Total carbohydrate levels measured in a series of cross sections along individual pulvini of 24-d-old plants showed only small differences between the day and night positions of the respective leaf. In contrast, the level of malate changed during diurnal leaf movement, especially in the central part of a pulvinus. The levels of glucose and fructose in the pulvinus increased towards the transition zones between the pulvinus and lamina, and pulvinus and petiole, and this trend was even more pronounced for starch. By contrast, sucrose levels were highest in the pulvinus proper. The transverse compartmentation of metabolites was studied in distinct, approx. 0.5-mm-thick tissue slices from the central part of a pulvinus. These were dissected further into up to 14 distinct subsamples (bundle, bundle sheath, motor tissues, flanks). Irrespective of the position of the leaf (day or night), the central vascular core and the surrounding bundle sheath had high levels of sucrose (up to 500 mmol-(kg DW)(-1)) and low levels of glucose and fructose (below 100 mmol-(kg DW)(-1)), while in the cortex the situation was reversed. In the night position the level of sucrose decreased by approx. 30% in the bundle sheath and the central vascular core but not in the other sections. We thus suggest that because of the relatively small diurnal changes in their cortical pools, soluble sugars are not involved in the osmotic processes resulting in leaf movement. In contrast, pulvini from 14-d-old plants showed an interesting diurnal change in starch and malate pools in the outermost layer of the extensor. Here starch increased at night while the malate pool was lowered nearly stoichiometrically. Inverse pool sizes were found in the day position of the respective leaves. Although less significant, the opposite diurnal variation occurred in samples taken from the flexor region. We thus were able to locate areas of different carbohydrate activities in the laminar pulvinus of P. coccineus. The central vascular core, including the bundle sheath, is involved in temporary storage of photoassimilates, and the cortical regions are responsible for osmotically driven leaf movement. The results are discussed with respect to guard-cell physiology.

In this paper I examine whether different suggestions made in the philosophy of perception can help us to explain and understand the phenomenal character of emotional experience. After having introduced the range of possible positions, I consider qualia-theory, reductive pure intentionalism and reductive impure intentionalism. I argue that qualia-theory can easily explain why emotions are phenomenal states at all but that it cannot account for the "inextricable link thesis" which is quite prominent in the philosophy of emotion. Reductive pure and impure intentionalism, in turn, seem to fit better with this thesis but they have difficulties to explain what makes emotions phenomenal states at all. Therefore, I finally discuss whether nonreductive intentionalism might be an option for explaining the phenomenal character of emotional experience.

No abstract

No abstract

No abstract