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Prostaglandins (PGs) participate in the regulation of vertebrate and in at least six insect orders' immune responses. We identified PGE 2 in midgut, fat body, Malpighian tubules, and ovarioles of Anopheles albimanus (Aa) mosquitoes. Our data indicate that PGE 2 synthesis in cultured midguts responds to the presence of two bacterial species, Micrococcus luteus and Klebsiella pneumoniae. The production of mRNA coding for antimicrobial peptides Aa-Attacin, Aa-Cecropin, and Aa-Gambicin was observed in cultured fat bodies and midguts. The production of these messengers was reduced in the presence of dexamethasone, and this effect was reversed by arachidonic acid. Adding PGE 2 to cultures resulted in increased Aa-cecropin mRNA and decreased Aa-attacin and Aa-gambicin mRNAs. Arch. Insect Biochem. Physiol. 68:14-25, 2008 KEYWORDS: insect immunity; arachidonic acid; dexamethasone; Anopheles albimanus; antimicrobial peptides INTRODUCTIONInsects resist the constant threat of invasion by microorganisms with integumental barriers and the presence of peritrophic matrix in their digestive tracts. When microbes overcome these first-line defenses, they encounter well-organized immune reactions that resemble mammalian innate immunity. Circulating hemocytes phagocytose microbial invaders and respond by forming microaggregates and nodules. Hemocytes also encapsulate those invaders, such as parasitoid eggs, too big to phagocytose (Stanley, 2006;Stanley and Miller, 2006). These cellular defense mechanisms are practically immediate upon microbial invasion, but complex humoral responses, including hemolymph clotting (Blandin and Levashina, 2004), melanization, and the production of antimicrobial peptides (Yu and Kanost, 2003;Lemaitre and Hoffmann, 2007) are deployed later.Eicosanoids including prostaglandins (PGs) are fatty acid metabolites that in mammals are produced by many cell types, including epithelial and immune cells, and play key roles in hemostasis and immune regulation, among many other functions (Harris et al., 2002). The biosynthesis of PGs in insects is initiated by a phospholipase A 2 (PLA 2 ) that cleaves membrane phospholipids (C20 polyunsaturated fatty acids including arachidonic acid [AA]), and the resulting products are converted to PGs' bioactive forms by cyclooxygenases (COX) (Stanley, 2000(Stanley, , 2006, but products of the lipoxygenase pathway (LOX) have been also documented (Galdelhak et al., 1995). The induction of eicosanoid biosynthesis by bacteria has been observed in several insect species (Stanley, 2006 and Miller, 2006). The information on the participation of eicosanoids in insect humoral immune responses is limited; PGs mediate the expression of genes encoding the antibacterial peptide cecropine and lysozime in the silkworm Bombyx mori (Morishima et al., 1997) and regulate the activation of prophenoloxidase (PPO) in two insect species, Galleria mellonella (Downer et al., 1997) and Rhodnius prolixus (García et al., 2004). However, they do not activate PPO in other insects (Lord et al., 2002;Goldswor...

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We propose a control strategy based on distributed adaptive leader-follower consensus algorithms for multiagent systems (MAS) affected by switching network events. The strategy allows each agent in the MAS to compute its own control input based on local information and information coming from its neighbors. In this sense, MAS distributed control laws are obtained where the coupling gain of the associated communication graph is adapted dynamically in real-time. The consensus algorithm is extended with a switching network topology approach, which ensures appropriate performance even when the MAS network topology is prone to arbitrary switching. A real-time experimental application is presented, where a MAS consisting of four rotorcraft UAS successfully performed the tasks of autonomously approaching and escorting a leader, even in the situation when the network topology was arbitrarily changing. Additionally, a Lyapunov stability analysis is included, which demonstrates that the tracking errors between leader and follower agents converge asymptotically to zero.Diverse efforts have been placed on the development of distributed coordination strategies. In general, MAS consensus methodologies [10] are the basis behind these strategies because they enable autonomous formation [11,12], flocking [13,14] rendezvous [15,16] and position synchronization [17].In a realistic scenario, the agents in a MAS are not homogeneous. For example, in a cooperative MAS team, it could be that a sensing agent performs the measurements, and sends its data to a data processing agent, which will perform estimation tasks and will possibly transmit an actuation command back to the sensing agent. Therefore, an effective communication is essential in the overall performance of the team. In general, a communication link between any two agents can be established when they explicitly exchange information by means of wireless communication links. In addition to enabling sharing data between agents, these links make possible, for example, RF-based agent detection and identification by means of teams of dynamic sensors [18]. On the other hand, an autonomous agent using on-board sensors (imaging, proximity or RF sensors) for estimating the position of a neighboring agent or target is also establishing an implicit unidirectional communication link among them [3]. Unfortunately, unreliable wireless channels and heavy computational loads may affect every kind of communication link and degrade the MAS performance.Some of the issues introduced by unreliable wireless transmission and their impact on estimation and control have been studied in [19,20]. Promising solutions for overcoming network issues have been presented in [21,22]; however, the studied scenarios considered static-agents exclusively. Most of the works on MAS assume ideal communication links, or ideal within a radius and nonexistent outside of it, which cannot be ensured in real-time implementation. The impact of unreliable communication channels on decision-making over a wireless network is s...

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