Biology subjects

Villalobos Sambucaro, M. J.

Publications and source records attributed to Villalobos Sambucaro, M. J..

3 recordsLinked to original sources

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↗

bioRxiv2022

Allatotropin in the Corpora Allata and Ovaries of Rhodnius prolixus: Probable in situ regulatory mechanisms

Originally described by Sir V. Wigglesworth in the Chagas disease vector Rhodnius prolixus, Juvenile Hormones (JHs) play critical roles during growth and reproduction. The JH described by Wigglesworth is the JH III skipped bisepoxide (JHSB3), and its titer in hemolymph varies along the 4th larval instar molting cycle. Allatotropin (AT), was originally characterized based on its ability to induce the synthesis of the JHs by the corpora allata (CA) in Lepidoptera. Beyond this function, AT has proved to be a myoregulator. Indeed, AT modulates muscle contractions in the gut, dorsal vessel and reproductive tissues. The presence of AT in the CA of 4th instar larvae of R. prolixus and the related species Triatoma infestans was previously shown, suggesting that AT might be involved in the regulation of JH synthesis in triatominae. Furthermore, the existence of allatotropic cells in this gland in T. infestans was also shown. This neuron-like cells show cytoplasmic processes projecting deeply between the cells engaged with JH synthesis. By using RT-qPCR we studied now the expression of both, AT and its receptor in the CA/CC complex along the 4th instar molting cycle, and in the ovaries of adult females. The expression of AT in the CA is highest between days 3 to 5 after meal, correlating with Mev-K and PPMev-D, two enzymes involved in the mevalonate pathway, as well as with the peak of JHSB3 on day 6. The results show that AT transcript is also present in the ovary suggesting a myoregulatory paracrine mechanism of regulation. Finally, our data suggest the existence of in situ mechanisms in the CA and ovaries of R. prolixus involving AT in both JHs synthesis and muscle contraction.

zoology↗

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↗