Locomotor behavior in relation to octopamine levels in the antLasius niger

The Intrinsic Nutrient Sensing Adipokinetic Hormone Producing Cells Function in Modulation of Metabolism, Activity, and Stress

All organisms confront the challenges of maintaining metabolic homeostasis in light of both variabilities in nutrient supplies and energetic costs of different physiologies and behaviors. While all cells are nutrient sensitive, only relative few cells within Metazoans are nutrient sensing cells. Nutrient sensing cells organize systemic behavioral and physiological responses to changing metabolic states. One group of cells present in the arthropods, is the adipokinetic hormone producing cells (APCs). APCs possess intrinsic nutrient sensors and receive contextual information regarding metabolic state through other endocrine connections. APCs express receptors for different hormones which modulate APC physiology and the secretion of the adipokinetic hormone (AKH). APCs are functionally similar to alpha cells in the mammalian pancreas and display a similar physiological organization. AKH release results in both hypertrehalosemia and hyperlipidemia through high affinity binding to the AKH receptor (AKHR). Another hallmark of AKH signaling is heightened locomotor activity, which accompanies starvation and is thought to enhance foraging. In this review, we discuss mechanisms of nutrient sensing and modulation of AKH release. Additionally, we compare the organization of AKH/AKHR signaling in different taxa. Lastly, we consider the signals that APCs integrate as well as recent experimental results that have expanded the functional repertoire of AKH signaling, further establishing this as both a metabolic and stress hormone.

Genetic Underpinnings of Host Manipulation by Ophiocordyceps as Revealed by Comparative Transcriptomics

Ant-infecting Ophiocordyceps fungi are globally distributed, host manipulating, specialist parasites that drive aberrant behaviors in infected ants, at a lethal cost to the host. An apparent increase in activity and wandering behaviors precedes a final summiting and biting behavior onto vegetation, which positions the manipulated ant in a site beneficial for fungal growth and transmission. We investigated the genetic underpinnings of host manipulation by: (i) producing a high-quality hybrid assembly and annotation of the Ophiocordyceps camponoti-floridani genome, (ii) conducting laboratory infections coupled with RNAseq of O. camponoti-floridani and its host, Camponotus floridanus, and (iii) comparing these data to RNAseq data of Ophiocordyceps kimflemingiae and Camponotus castaneus as a powerful method to identify gene expression patterns that suggest shared behavioral manipulation mechanisms across Ophiocordyceps-ant species interactions. We propose differentially expressed genes tied to ant neurobiology, odor response, circadian rhythms, and foraging behavior may result by activity of putative fungal effectors such as enterotoxins, aflatrem, and mechanisms disrupting feeding behaviors in the ant.

Distribution of biogenic amines in the cricket central nervous system

The distribution of biogenic amines, their precursors, and metabolites in the central nervous system (CNS) of the cricket was determined using HPLC with electrochemical detection. Three biogenic amines, octopamine (OA), dopamine (DA), and 5-hydroxytryptamine (5-HT); two precursors, tyramine and tryptophan; and two metabolites, synephrine and 5-hydroxyindole-3-acetic acid, were detected in all ganglia. In the brain, 5-HT occurred in the largest quantities followed by OA, while in other ganglia OA occurred in the largest quantities followed by 5-HT and DA. In all ganglia, the amount of OA was two to nine times greater than that of DA. The results are discussed in comparison with different insect species.

Prenatal ontogenesis of p-, m-octopamine and phenylethanolamine in relation to catecholamines and their metabolizing enzymes in the developing rat brain and heart

Non-catecholamines such as phenylethanolamine and p-octopamine are present in many invertebrate nervous systems, sometimes in large amounts. These amines are normally present in the rat brain at much lower levels, p- and m-octopamine are present at trace levels in the mammalian brain. The prenatal development of these amines was studied in comparison with those of noradrenaline and dopamine. The activities of tyrosine hydroxylase, dopa decarboxylase, dopamine beta-hydroxylase and monoamine oxidase were determined in parallel. Phenylethanolamine and p-octopamine are more abundant in the brain between 13 and 17 fetal days than dopamine and noradrenaline but decrease after 17 days whereas the levels of m-octopamine and the two catecholamines increase afterwards. Dopa decarboxylase, dopamine beta-hydroxylase and tyrosine hydroxylase are detected early in fetal life (13, 15 and 14.5 days respectively) but monoamine oxidase activity was not found before 18 days.