Hydra as an animal model system in physiology

Hydra has been used as a model in different topics in biology, including physiology. It pertains to the Phylum Cnidaria, an ancestral group of Metazoa that shares a common ancestor with Bilateria. Hydra provides an experimental framework to analyze mechanisms that regulate the homeostasis and, due to the high level of gene conservation, can be easily extrapolated to other animal groups. We use this model to analyze physiological and evolutionary aspects of communication systems activated by food, and by the peptide messengers, Allatotropin (AT) and Allatostatin-C (AST-C). Using immunohistochemistry, quantum dots, bioinformatic, and physiological assays, we show that these systems are present in Hydra regulating feeding behavior. We analyze the regulation of the extrusion of the hypostome (that contains the mouth), showing that, whereas AT mimics the effect of the food, AST-C acts as antagonist. We show that those effects depend on changes in the cytosolic Ca2+ concentration, revealing the specific signaling pathway activated. Our data support the ancestral functions and conservation of these signaling systems that control myoregulatory activities related with feeding.Hydra ha sido usada como modelo para el estudio de diferentes aspectos de la biología, incluyendo fisiología. Pertenece al phylum Cnidaria, grupo ancestral de metazoos que comparte un ancestro común con Bilateria. El modelo de Hydra representa un sistema de estudio útil para analizar el mantenimiento de la homeostasis que, debido al alto grado de conservación respecto de los metazoos, puede ser extrapolado a otros grupos animales. Analizamos en Hydra tanto aspectos fisiológicos, como evolutivos de sistemas de comunicación activados por el alimento y los péptidos allatotropina(AT) y allatostatina C (AST-C). Mediante análisis de datos inmunohistoquímicos, quantum dots, fisiológicos y de bioinformática demostramos que estos sistemas de comunicación están presentes en Hydra regulando el comportamiento alimentario. analizando la regulación de la extrusión del hipostoma (estructura que contiene la boca) demostramos que AT mimetiza el efecto del alimento, estimulando su extrusión, mientras que AST-C se comporta como antagosnista. Mostramos que estos efectos dependen de cambios en la concentración de Ca+2 citosólico, revelando sus vías de señalización especifica. Nuestros datos muestran las funciones y conservación de estos sistemas de comunicación, desde organismos ancestrales como Cnidarios.Sociedad Argentina de Fisiologí

The Evolutionary History of The Orexin/Allatotropin GPCR Family: From Placozoa and Cnidaria to Vertebrata

Peptidic messengers constitute a highly diversified group of intercellular messengers widely distributedin nature that regulate a great number of physiological processes in Metazoa. Being crucial for life, itseem that they have appeared in the ancestral group from which Metazoa evolved, and were highlyconserved along the evolutionary process. Peptides act mainly through G-protein coupled receptors(GPCRs), a family of transmembrane molecules. GPCRs are also widely distributed in nature beingpresent in metazoan, but also in Choanoflagellata and Fungi. Among GPCRs, the Allatotropin/Orexin(AT/Ox) family is particularly characterized by the presence of the DRW motif in the second intracellularloop (IC Loop 2), and seems to be present in Cnidaria, Placozoa and in Bilateria, suggesting that it waspresent in the common ancestor of Metazoa. Looking for the evolutionary history of this GPCRs wesearched for corresponding sequences in public databases. Our results suggest that AT/Ox receptorswere highly conserved along evolutionary process, and that they are characterized by the presenceof the E/DRWYAI motif at the IC Loop 2. Phylogenetic analyses show that AT/Ox family of receptorsreflects evolutionary relationships that agree with current phylogenetic understanding in Actinopterygiiand Sauropsida, including also the largely discussed position of TestudinesFil: Alzugaray, Maria Eugenia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Bruno, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; ArgentinaFil: Villalobos Sambucaro, María José. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Ronderos, Jorge Rafael. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; Argentin

The Evolutionary History of The Orexin/Allatotropin GPCR Family : From Placozoa and Cnidaria to Vertebrata

Peptidic messengers constitute a highly diversifed group of intercellular messengers widely distributed in nature that regulate a great number of physiological processes in Metazoa. Being crucial for life, it 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 family of transmembrane molecules. GPCRs are also widely distributed in nature being present in metazoan, but also in Choanofagellata and 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 was present in the common ancestor of Metazoa. Looking for the evolutionary history of this GPCRs we searched for corresponding sequences in public databases. Our results suggest that AT/Ox receptors were highly conserved along evolutionary process, and that they are characterized by the presence of the E/DRWYAI motif at the IC Loop 2. Phylogenetic analyses show that AT/Ox family of receptors refects evolutionary relationships that agree with current phylogenetic understanding in Actinopterygii and Sauropsida, including also the largely discussed position of Testudines.Facultad de Ciencias Naturales y Muse

Expression of islet neogenesis-associated protein in islets of normal hamsters

The aim of the present study was to test the possible presence and expression of islet neogenesis-associated protein (INGAP) in islet cells of normal adult hamsters. Pancreata from normal male Syrian hamsters were removed to perform the following studies. (i) Western blot analysis using the cytosolic fraction from homogenates of isolated islets, exocrine tissue and whole pancreas, and rabbit INGAP-specific antibody. (ii) Immunohistochemical identification of INGAP-positive cells in fixed sections of intact pancreata, fresh and 72 h cultured islets (isolated by collagenase digestion), and smears of exocrine pancreatic cells, using the same INGAP-specific antibody and streptavidin-biotin complex. (iii) RT-PCR using total RNA extracted from isolated islets and from exocrine tissue as template, and a specific pair of primers. (iv) Control of the sequence of the PCR products. INGAP protein was identified by Western blot in the cytosolic fraction of homogenates from fresh isolated islets, exocrine cells and whole fresh pancreas. INGAP-immunopositive cells were observed in duct, exocrine and islet cells in either fixed intact or digested pancreatic tissue. INGAP mRNA was identified in samples of total RNA from fresh and cultured isolated islets and from exocrine cells. Our data demonstrate that INGAP is present and expressed in islets and in exocrine pancreatic cells of normal hamsters. The ubiquitous localization of INGAP suggests its possible role in the physiological process of islet growth and its protective effect upon streptozotocin-induced diabetes.Centro de Endocrinología Experimental y Aplicad

Changes in islet plasma membrane calcium-ATPase activity and isoform expression induced by insulin resistance

We studied the effect of insulin resistance (IR) induced by administration of a fructose-rich diet (FRD) to normal Wistar rats for 21 days, upon islet plasma membrane calcium ATPases (PMCAs) and insulin secretion. FRD rats showed significantly higher triglyceride and insulin levels, insulin:glucose ratio and HOMA-IR index than controls. FRD islets released significantly more insulin in response to glucose and showed (a) marked changes in PMCA isoform protein content (decreased PMCA 2 and increased PMCA 3), (b) a decrease in total PMCAs activity, and (c) higher levels of cytosolic calcium [Ca2+]i. The lower PMCAs activity with the resultant increase in [Ca2+]i would favor the compensatory greater release of insulin necessary to cope with the IR state present in FRD rats and to maintain normal glucose homeostasis. Thus, changes in PMCAs activity and isoform expression play a modulatory role upon insulin secretion during long-term adaptation to an increased hormone demand.Centro de Endocrinología Experimental y Aplicad

The juvenile hormone described in Rhodnius prolixus by Wigglesworth is juvenile hormone III skipped bisepoxide

Juvenile hormones (JHs) are sesquiterpenoids synthesized by the corpora allata (CA). They play critical roles during insect development and reproduction. The frst JH was described in 1934 as a “metamorphosis inhibitory hormone” in Rhodnius prolixus by Sir Vincent B. Wigglesworth. Remarkably, in spite of the importance of R. prolixus as vectors of Chagas disease and model organisms in insect physiology, the original JH that Wigglesworth described for the kissing-bug R. prolixus remained unidentifed. We employed liquid chromatography mass spectrometry to search for the JH homologs present in the hemolymph of fourth instar nymphs of R. prolixus. Wigglesworth’s original JH is the JH III skipped bisepoxide (JHSB3), a homolog identifed in other heteropteran species. Changes in the titer of JHSB3 were studied during the 10-day long molting cycle of 4th instar nymph, between a blood meal and the ecdysis to 5th instar. In addition we measured the changes of mRNA levels in the CA for the 13 enzymes of the JH biosynthetic pathway during the molting cycle of 4th instar. Almost 90 years after the frst descriptions of the role of JH in insects, this study fnally reveals that the specifc JH homolog responsible for Wigglesworth’s original observations is JHSB3.Fil: Villalobos Sambucaro, María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; ArgentinaFil: Nouzova, Marcela. Florida International University; Estados UnidosFil: Ramirez, Cesar E.. Florida International University; Estados UnidosFil: Alzugaray, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; ArgentinaFil: Fernandez-Lima, Francisco. Florida International University; Estados UnidosFil: Ronderos, Jorge Rafael. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Histología y Embriología Animal; ArgentinaFil: Noriega, Fernando. Florida International University; Estados Unido

Regulación de la masa de células beta en hamsters normales tratados con NGAP-PP

El objetivo deltrabajo es estudiar el efecto de la administración de INGAP-PP a hamsters adultos normales sobre la regulación de la masa de células β y la homeostasis de la glucosa.Eje: Salud públicaFacultad de Ciencias Médica

Expression of islet neogenesis-associated protein in islets of normal hamsters

The aim of the present study was to test the possible presence and expression of islet neogenesis-associated protein (INGAP) in islet cells of normal adult hamsters. Pancreata from normal male Syrian hamsters were removed to perform the following studies. (i) Western blot analysis using the cytosolic fraction from homogenates of isolated islets, exocrine tissue and whole pancreas, and rabbit INGAP-specific antibody. (ii) Immunohistochemical identification of INGAP-positive cells in fixed sections of intact pancreata, fresh and 72 h cultured islets (isolated by collagenase digestion), and smears of exocrine pancreatic cells, using the same INGAP-specific antibody and streptavidin-biotin complex. (iii) RT-PCR using total RNA extracted from isolated islets and from exocrine tissue as template, and a specific pair of primers. (iv) Control of the sequence of the PCR products. INGAP protein was identified by Western blot in the cytosolic fraction of homogenates from fresh isolated islets, exocrine cells and whole fresh pancreas. INGAP-immunopositive cells were observed in duct, exocrine and islet cells in either fixed intact or digested pancreatic tissue. INGAP mRNA was identified in samples of total RNA from fresh and cultured isolated islets and from exocrine cells. Our data demonstrate that INGAP is present and expressed in islets and in exocrine pancreatic cells of normal hamsters. The ubiquitous localization of INGAP suggests its possible role in the physiological process of islet growth and its protective effect upon streptozotocin-induced diabetes.Centro de Endocrinología Experimental y Aplicad

Allatotropin: an ancestral myotropic neuropeptide involved in feeding

Background: Cell-cell interactions are a basic principle for the organization of tissues and organs allowing them to perform integrated functions and to organize themselves spatially and temporally. Peptidic molecules secreted by neurons and epithelial cells play fundamental roles in cell-cell interactions, acting as local neuromodulators, neurohormones, as well as endocrine and paracrine messengers. Allatotropin (AT) is a neuropeptide originally described as a regulator of Juvenile Hormone synthesis, which plays multiple neural, endocrine and myoactive roles in insects and other organisms. Methods: A combination of immunohistochemistry using AT-antibodies and AT-Qdot nanocrystal conjugates was used to identify immunoreactive nerve cells containing the peptide and epithelial-muscular cells targeted by AT in Hydra plagiodesmica. Physiological assays using AT and AT- antibodies revealed that while AT stimulated the extrusion of the hypostome in a dose-response fashion in starved hydroids, the activity of hypostome in hydroids challenged with food was blocked by treatments with different doses of AT-antibodies. Conclusions: AT antibodies immunolabeled nerve cells in the stalk, pedal disc, tentacles and hypostome. AT-Qdot conjugates recognized epithelial-muscular cell in the same tissues, suggesting the existence of anatomical and functional relationships between these two cell populations. Physiological assays indicated that the AT-like peptide is facilitating food ingestion. Significance: Immunochemical, physiological and bioinformatics evidence advocates that AT is an ancestral neuropeptide involved in myoregulatory activities associated with meal ingestion and digestion.Facultad de Ciencias Naturales y Muse

The juvenile hormone described in <i>Rhodnius prolixus</i> by Wigglesworth is juvenile hormone III skipped bisepoxide

Juvenile hormones (JHs) are sesquiterpenoids synthesized by the corpora allata (CA). They play critical roles during insect development and reproduction. The first JH was described in 1934 as a "metamorphosis inhibitory hormone" in Rhodnius prolixus by Sir Vincent B. Wigglesworth. Remarkably, in spite of the importance of R. prolixus as vectors of Chagas disease and model organisms in insect physiology, the original JH that Wigglesworth described for the kissing-bug R. prolixus remained unidentified. We employed liquid chromatography mass spectrometry to search for the JH homologs present in the hemolymph of fourth instar nymphs of R. prolixus. Wigglesworth's original JH is the JH III skipped bisepoxide (JHSB3), a homolog identified in other heteropteran species. Changes in the titer of JHSB3 were studied during the 10-day long molting cycle of 4th instar nymph, between a blood meal and the ecdysis to 5th instar. In addition we measured the changes of mRNA levels in the CA for the 13 enzymes of the JH biosynthetic pathway during the molting cycle of 4th instar. Almost 90 years after the first descriptions of the role of JH in insects, this study finally reveals that the specific JH homolog responsible for Wigglesworth's original observations is JHSB3.Facultad de Ciencias Naturales y MuseoConsejo Nacional de Investigaciones Científicas y Técnica