Adipokinetic hormone enhances laminarin and bacterial lipopolysaccharide-induced activation of the prophenoloxidase cascade in the African migratory locust, Locusta migratoria

Lom-AKH-I enhances the activation in vivo of prophenoloxidase in the haemolymph of the African migratory locust, Locusta migratoria, in response to challenge with laminarin. AKH does not influence the speed or initial magnitude of the phenoloxidase response to laminarin, but prolongs the period of activation of the enzyme in a dose-dependent manner. Injections of preparations of bacterial lipopolysaccharide (LPS) do not activate prophenoloxidase in vivo, but co-injection of Lom-AKH-I with commercial preparations of LPS from Klebsiella pneumoniae, Escherichia coli, or Shigella flexneri (but not one from Pseudomonas aeroginosa) results in dose-dependent increases in the levels of phenoloxidase that persist in the haemolymph for several hours. It is argued that the effects of AKH on phenoloxidase activation in locusts described here are, at least in part, related directly to changes in lipid metabolism brought about by the hormone

Adipokinetic hormone enhances nodule formation and phenoloxidase activation in adult locusts injected with bacterial lipopolysaccharide

Interactions between the locust endocrine and immune systems have been studied in vivo in relation to nodule formation and activation of the prophenoloxidase cascade in the haemolymph. Injection of bacterial lipopolysaccharide (LPS) extracted from Escherichia coli induces nodule formation in larval and adult locusts but does not increase phenoloxidase activity in the haemolymph. Nodule formation starts rapidly after injection of LPS and is virtually complete within 8 h, nodules occurring mainly associated with the dorsal diaphragm on either side of the heart, but sometimes with smaller numbers associated with the ventral diaphragm on either side of the nerve cord. Co-injection of adipokinetic hormone-I (Lom-AKH-I) with LPS stimulates greater numbers of nodules to be formed in larval and adult locusts, and activates phenoloxidase in the haemolymph of mature adults but not of nymphs. The effect of co-injection of Lom-AKH-I with LPS on nodule formation is seen at low doses of hormone; only 0.4 pmol of Lom-AKH-I per adult locust is needed to produce a 50% increase in the number of nodules formed. When different components of LPS from the E. coli Rd mutant are tested, the mono- and the diphosphoryl Lipid A components have similar effects to the intact LPS. Remarkably, detoxified LPS activates phenoloxidase in the absence of Lom-AKH-I, although co-injection with hormone does enhance this response. Both diphosphoryl Lipid A and detoxified LPS induce a level of nodule formation that is enhanced by co-injection of Lom-AKH-I, but monophosphoryl Lipid A does not initiate nodule formation even when injected with hormone. Co-injection of a water-soluble inhibitor of eicosanoid synthesis, diclofenac (2-[(2, 6-dichlorophenyl)amino] benzeneacetic acid), reduces nodule formation in response to injections of LPS (both in the absence and presence of hormone) in a dose-dependent manner, but does not prevent activation of phenoloxidase in adult locusts. It is shown that nodule formation and activation of the prophenoloxidase in locust haemolymph can both be enhanced by Lom-AKH–I, but it is argued that these processes involve distinct mechanisms in which eicosanoid synthesis is important for nodule formation, but not for the increased phenoloxidase activity

Internal audit effectiveness as a boon to public procurement performance: a multi mediation model

AbstractAs part of Governments of Ghana efforts to deal with misappropriation of public sector resources, the Internal Audit Agency Act, 2003 (Act 658) was established to ensure probity, accountability, and transparency in the management of public sector resources, yet there is a high Corruption Perception Index in Ghana as asserted by the Transparent International 2021 release. To address this concern, our paper is aimed to develop a new model to explain the extent to which internal audit effectiveness (IAE) could be used to build strong organizational resilience as a mechanism through which efficiency in public procurement could be achieved while reducing public sector corruption incidence. Data have been collected from a cross-section of public sector workers. The structural equation modeling approach has been used to analyze the survey data. Our results have shown that cultural, and strategic resilience dimensions of organizational resilience significantly mediate the relationship between IAE and procurement performance. These results have implications for re-enforcement of audit regulations to ensure transparency in managing public sector resources with a focus on reducing negative public sector corruption perception