a-Synuclein is a synaptic modulatory protein implicated in the pathogenesis of Parkinson disease. The precise functions of this small cytosolic protein are still under investigation. a-Synuclein has been proposed to regulate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins involved in vesicle fusion. Interestingly, a-synuclein fails to interact with SNARE proteins in conventional protein-binding assays, thus suggesting an indirect mode of action. As the structural and functional properties of both a-synuclein and the SNARE proteins can be modified by arachidonic acid, a common lipid regulator, we analysed this possible tripartite link in detail. Here, we show that the ability of arachidonic acid to stimulate SNARE complex formation and exocytosis can be controlled by a-synuclein, both in vitro and in vivo. a-Synuclein sequesters arachidonic acid and thereby blocks the activation of SNAREs. Our data provide mechanistic insights into the action of a-synuclein in the modulation of neurotransmission.

Transmitted light images showed an intricate and dynamic cytoplasmic structural network in cultured bovine chromaffin cells observed under high magnification. These structures were sensitive to chemicals altering F-actin-myosin and colocalised with peripheral F-actin, β-actin and myosin II. Interestingly, secretagogues induced a Ca2+-dependent, rapid (>10 second) and transitory (60-second cycle) disassembling of these cortical structures. The simultaneous formation of channel-like structures perpendicular to the plasmalemma conducting vesicles to the cell limits and open spaces devoid of F-actin in the cytoplasm were also observed. Vesicles moved using F-actin pathways and avoided diffusion in open, empty zones. These reorganisations representing F-actin transfer from the cortical barrier to the adjacent cytoplasmic area have been also confirmed by studying fluorescence changes in cells expressing GFP-β-actin. Thus, these data support the function of F-actin-myosin II network acting simultaneously as a barrier and carrier system during secretion, and that transmitted light images could be used as an alternative to fluorescence in the study of cytoskeleton dynamics in neuroendocrine cells.

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Abstract. The paper is aimed at a methodological development in biological pest control. The 10 considered one pest two-agent system is modelled as a verticum-type system. Originally, linear 11 verticum-type systems were introduced by one of the authors for modelling certain industrial 12 systems. These systems are hierarchically composed of linear subsystems such that a part of the 13 state variables of each subsystem affect the dynamics of the next subsystem. Recently, 14 verticum-type system models have been applied to population ecology as well, which required 15 the extension of the concept a verticum-type system to the nonlinear case. 16In the present paper the general concepts and technics of nonlinear verticum-type control 17 systems are used to obtain biological control strategies in a two-agent system. For the 18 illustration of this verticum-type control, these tools of mathematical systems theory are applied 19 to a dynamic model of interactions between the egg and larvae populations of the sugarcane 20 borer (Diatraea saccharalis) and its parasitoids: the egg parasitoid Trichogramma galloi and the 21 larvae parasitoid Cotesia flavipes. 22In this application a key role is played by the concept of controllability, which means that it is 23 possible to steer the system to an equilibrium in given time. In addition to a usual linearization, 24 the basic idea is a decomposition of the control of the whole system into the control of the 25 subsystems, making use of the verticum structure of the population system. The main aim of 26 this study is to show several advantages of the verticum (or decomposition) approach over the 27 classical control theoretical model (without decomposition). For example, in the case of 28 verticum control the pest larval density decreases below the critical threshold value much 29 quicker than without decomposition. Furthermore, it is also shown that the verticum approach 30 may be better even in terms of cost effectiveness. The presented optimal control methodology 31 also turned out to be an efficient tool for the "in silico" analysis of the cost-effectiveness of 32 different biocontrol strategies, e.g. by answering the question how far it is cost-effective to 33 speed up the reduction of the pest larvae density, or along which trajectory this reduction should 34 be carried out. 35 36

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