Alzugaray, M. E. | bioRxiv Science

bioRxiv2023

Mechanisms Controlling Hemolymph Circulation Under Resting Conditions In The Chagas Disease Vector Rhodnius prolixus (Stal)

Chagas disease vectors can ingest several times its own volume in blood with each meal. This ad libitum feeding causes an intense process of diuresis inducing the insect to eliminate a large quantity of urine during the next few hours. This process, which is under the control of endocrine and neuroendocrine systems is necessary to restore homeostasis, and to begin physiological mechanisms leading to growth and reproduction. To ensure diuresis, the speed of circulation of the hemolymph must be increased to allow the Malpighian tubules to produce the urine. Behind this acute phenomenon, triatominae insects can spend several weeks without feeding. In this way, it could be assumed that during most of the time of life the insect is in a resting condition. Triatominae circulatory system is quite simple, including a dorsal vessel which pumps hemolymph in an anterograde direction. The return is caused by peristaltic contractions of the anterior midgut. While the mechanisms controlling the circulation of the hemolymph during post-prandial diuresis was largely analysed, the mechanisms controlling it during resting conditions is poorly understood. In this study we analyse several canonical pathways (i.e. L-type VGCC; GPCR; RyR; IP3R) and a novel system represented by the recently characterized Piezo proteins. Our results show that during the resting condition hemolymph circulation depends on a cross-talk between myogenic activity, inhibitory and stimulatory cell messengers, and also Piezo proteins. We present for the first time the existence of a putative Piezo protein in Hemiptera.

physiology↗

bioRxiv2018

THE EVOLUTIONARY HISTORY OF THE OREXIN/ALLATOTROPIN GPCR FAMILY: FROM PLACOZOA AND CNIDARIA TO VERTEBRATA

Cell-cell communication is a basic principle in all organisms, necessary to facilitate the coordination and integration between cell populations. These systems act by mean of chemical messengers. Peptides constitute a highly diversified group of intercellular messengers widely distributed in nature, and regulate a great number of physiological processes in Metazoa. Being crucial for life, it would seem that they have appeared in the ancestral group from which Metazoa evolved, and were highly conserved along the evolutionary process. Peptides act mainly through G-protein coupled receptors (GPCRs), a great family of transmembrane molecules. GPCRs are also widely distributed in nature being present not only in metazoan, but also in Choanoflagellata (unicellular eukariotes related with metazoans), and even in Fungi. Among GPCRs, the Allatotropin/Orexin (AT/Ox) family is particularly characterized by the presence of the DRW motif in the second intracellular loop (IC Loop 2), and seems to be present in Cnidaria, Placozoa and in Bilateria, suggesting that it also was present in the common ancestor of Metazoa. Looking for the evolutionary history of this GPCR family we searched in the GenBank for sequences corresponding to this family of receptors (i.e. seven transmembrane domain and the E/DRW motif at the second IC Loop 2). Our results show that AT/Ox receptors were highly conserved along evolutionary history of Metazoa, and that they might be defined by the presence of the E/DRWYAI motif at the level of IC Loop 2. Molecular phylogenetic analyses performed by Maximum Likelihood method suggest that AT/Ox family of receptors reflects evolutionary relationships that agree with current understanding of phylogenetic relationships in Actinopterygii and Sauropsida, including also the largely discussed position of Testudines.

evolutionary biology↗