SummaryCalcium is considered the most important second messenger at fertilization. Transient rele... more SummaryCalcium is considered the most important second messenger at fertilization. Transient release from intracellular stores is modulated through both agonist-gated channels, IP3Rs and RyRs, which can be found individually or together depending on the oocyte species. Using the four commonly used compounds (thimerosal, caffeine, heparin and ruthenium red), we investigated the existence and interdependence of both IP3Rs and RyRs in matureBufo arenarumoocytes. We found that caffeine, a well known specific RyRs agonist, was able to trigger oocyte activation in a dose-dependent manner. Microinjection of 10 mM caffeine showed 100% of oocytes exhibiting characteristic morphological criteria of egg activation. Ruthenium red, the specific RyR blocker, was able to inhibit oocyte activation induced either by sperm or caffeine. Our present findings provide the first reported evidence of the existence of RyR in frogs. We further explored the relationship between IP3Rs and RyRs inB. arenarumooc...
SummaryTransient increases in the concentration of cytosolic Ca2+are essential for triggering egg... more SummaryTransient increases in the concentration of cytosolic Ca2+are essential for triggering egg activation events. Increased Ca2+results from its rapid release from intracellular stores, mainly mediated by one or both intracellular calcium channels: the inositol trisphosphate receptor (IP3R) and the ryanodine receptor (RyR). Several regulatory pathways that tailor the response of these channels to the specific cell type have been proposed. Among its many modulatory actions, calcium can serve as an activator of a cytosolic phospholipase A2(cPLA2), which releases arachidonic acid from phospholipids of the endoplasmic reticulum as well as from the nuclear envelope. Previous studies have suggested that arachidonic acid and/or its metabolites were able to modulate the activity of several ion channels. Based on these findings, we have studied the participation of the phospholipase A2(PLA2) pathway in the process ofBufo arenarumoocyte activation and the interrelation between any of its m...
SummaryWe investigated the participation of Gαiprotein and of intracellular cAMP levels on sponta... more SummaryWe investigated the participation of Gαiprotein and of intracellular cAMP levels on spontaneous and progesterone-mediated maturation inRhinella arenarumfully grown follicles and denuded oocytes.Although progesterone is the established maturation inducer in amphibians,Rhinella arenarumoocytes obtained during the reproductive period (competent oocytes) resume meiosis with no need for an exogenous hormonal stimulus if deprived of their enveloping follicular cells, a phenomenon called spontaneous maturation. In amphibian oocytes, numerous signalling mechanisms have been involved in the rapid, non-genomic, membrane effects of progesterone, but most of these are not fully understood.The data presented here demonstrate that activation of the Gαiprotein by Mas-7 induced maturation in non-competent oocytes and also an increase in GVBD (germinal vesicle breakdown) in competent oocytes. Similar results were obtained with intact follicles independent of the season. The activation of aden...
RESUMEN: Las leyes que rigen las instituciones de educación superior y el perfil del egresado de ... more RESUMEN: Las leyes que rigen las instituciones de educación superior y el perfil del egresado de la carrera de Bioquímica exigen la form ación de profesionales capaces de adaptarse a los cambios científicos-tecnológicos, c on alta capacidad de análisis, de interpretación y creatividad, capaces de actualizar se continuamente en conocimientos y tecnologías. Particularmente, la Cátedra de Histolo gía de la Facultad de Bioquímica (U.N.T.) detecta bajo rendimiento y desmotivación en sus alu mnos. Objetivos: Caracterizar el proceso de enseñanza-aprendizaje tr dicional – Identificar competencias profesionales ausentes Implementar e str tegias metodológicas que promuevan dichas competencias. Metodología: Fase de Diagnóstico: Se realizaron encuestas a alumnos que cursaron la asignatura, se complementaron con entrevistas a alu mnos y docentes Fase de Ejecución: Se planificaron e implementaron prácticas de enseñanza y evaluación superadoras. Se evaluaron los resultados mediante informe de un d...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the o... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which display an incomplete metamorphosis. We use Rhodnius prolixus as a convenient experimental model to test two hypotheses: (1) the role of neuropeptides that regulate ecdysis in Holometabola is conserved in hemimetabolous insects; and (2) the neuropeptides regulating ecdysis play a role in the regulation of female reproduction during the adult stage. The RNA interference-mediated reduction of ecdysis triggering hormone (ETH) mRNA levels in fourth-instar nymphs resulted in lethality at the expected time of...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the o... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which display an incomplete metamorphosis. We use Rhodnius prolixus as a convenient experimental model to test two hypotheses: (1) the role of neuropeptides that regulate ecdysis in Holometabola is conserved in hemimetabolous insects; and (2) the neuropeptides regulating ecdysis play a role in the regulation of female reproduction during the adult stage. The RNA interference-mediated reduction of ecdysis triggering hormone (ETH) mRNA levels in fourth-instar nymphs resulted in lethality at the expected time of...
SummaryEgg activation, which includes cortical granule exocytosis, resumption and completion of m... more SummaryEgg activation, which includes cortical granule exocytosis, resumption and completion of meiosis and pronuclear formation culminates in the first mitotic cleavage. However, the mechanism through which the fertilizing sperm induces this phenomenon is still controversial. We investigated the effect of the microinjection of homologous sperm soluble fractions obtained by fast protein liquid chromatography (FPLC) from reacted sperm (without acrosome) and non-reacted sperm on the activation of Rhinella arenarum oocytes matured in vitro. The FPLC-purified sperm fraction obtained from reacted or non-reacted sperm is able to induce oocyte activation when it is microinjected. This fraction has a 24 kDa protein and showed phospholipase C (PLC) activity in vitro, which was inhibited by D-609 but not by n-butanol or neomycin, suggesting that it is a PLC that is specific for phosphatidylcholine (PC-PLC). The assays conducted using inhibitors of inositol triphosphate (IP3) and ryanodine rec...
SummaryDuring activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastr... more SummaryDuring activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastructural changes in the vitelline envelope. These changes involve modifications in the structure of the vitelline envelope and formation of a fertilization envelope (FE) that can no longer be penetrated by sperm. In Bufo arenarum, as the egg traverses the oviduct, the vitelline envelope is altered by a trypsin-like protease secreted by the oviduct, which induces an increased susceptibility of the vitelline envelope to sperm lysins. Full-grown oocytes of B. arenarum, matured in vitro by progesterone, are polyspermic, although cortical granule exocytosis seems to occur within a normal chronological sequence. These oocytes can be fertilized with or without trypsin treatment, suggesting that the vitelline envelope is totally sperm-permeable. Vitelline envelopes without trypsin treatment cannot retain either gp90 or gp96. This suggests that these glycoproteins are involved in the block to poly...
SummaryIn the fertilization of most animals, egg activation is accompanied by an increase in cyto... more SummaryIn the fertilization of most animals, egg activation is accompanied by an increase in cytoplasmatic Ca2+; however, the mechanism through which the fertilizing sperm induce this phenomenon is still controversial. An increase in intracellular free Ca2+is required to trigger egg activation events, a process that includes cortical granule exocytosis, resumption and completion of meiosis and DNA replication, and culminates in the first mitotic cleavage. In this work, we investigated the effect of microinjection and incubation of different fractions of homologous sperm extract on the activation ofBufo arenarumoocytes maturedin vitro. Two heat treatment-sensitive fractions obtained by chromatography were able to induce oocyte activation. The sperm fraction, which contained a 24 kDa protein, induced 90% activation when it was microinjected into the oocytes. Whilst the sperm fraction, which contained a 36 kDa protein, was able to induce about 70% activation only when it was applied on...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and the shedding of t... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and the shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which displays an incomplete metamorphosis.Here, we studied neuropeptides related to ecdysis regulation in the hemi-metabolous insect Rhodnius prolixus. The RNA interference-mediated reduction of ETH expression in fourth instar nymphs resulted in lethality at the expected time of ecdysis, thereby showing its crucial role in this process. Furthermore, the results revealed the involvement of ETH in the regulation of reproductive fitness. Different from holometabolous, the knockdown of ETH in adult females l...
Abstract We examined the histological structure of 8 skin areas thought to contain cutaneous glan... more Abstract We examined the histological structure of 8 skin areas thought to contain cutaneous glands of potential importance in scent communication in 16 brown brocket deerMazama gouazoubira Fisher, 1814, using standard histological techniques. Frontal areas and ...
SummaryCalcium is considered the most important second messenger at fertilization. Transient rele... more SummaryCalcium is considered the most important second messenger at fertilization. Transient release from intracellular stores is modulated through both agonist-gated channels, IP3Rs and RyRs, which can be found individually or together depending on the oocyte species. Using the four commonly used compounds (thimerosal, caffeine, heparin and ruthenium red), we investigated the existence and interdependence of both IP3Rs and RyRs in matureBufo arenarumoocytes. We found that caffeine, a well known specific RyRs agonist, was able to trigger oocyte activation in a dose-dependent manner. Microinjection of 10 mM caffeine showed 100% of oocytes exhibiting characteristic morphological criteria of egg activation. Ruthenium red, the specific RyR blocker, was able to inhibit oocyte activation induced either by sperm or caffeine. Our present findings provide the first reported evidence of the existence of RyR in frogs. We further explored the relationship between IP3Rs and RyRs inB. arenarumooc...
SummaryTransient increases in the concentration of cytosolic Ca2+are essential for triggering egg... more SummaryTransient increases in the concentration of cytosolic Ca2+are essential for triggering egg activation events. Increased Ca2+results from its rapid release from intracellular stores, mainly mediated by one or both intracellular calcium channels: the inositol trisphosphate receptor (IP3R) and the ryanodine receptor (RyR). Several regulatory pathways that tailor the response of these channels to the specific cell type have been proposed. Among its many modulatory actions, calcium can serve as an activator of a cytosolic phospholipase A2(cPLA2), which releases arachidonic acid from phospholipids of the endoplasmic reticulum as well as from the nuclear envelope. Previous studies have suggested that arachidonic acid and/or its metabolites were able to modulate the activity of several ion channels. Based on these findings, we have studied the participation of the phospholipase A2(PLA2) pathway in the process ofBufo arenarumoocyte activation and the interrelation between any of its m...
SummaryWe investigated the participation of Gαiprotein and of intracellular cAMP levels on sponta... more SummaryWe investigated the participation of Gαiprotein and of intracellular cAMP levels on spontaneous and progesterone-mediated maturation inRhinella arenarumfully grown follicles and denuded oocytes.Although progesterone is the established maturation inducer in amphibians,Rhinella arenarumoocytes obtained during the reproductive period (competent oocytes) resume meiosis with no need for an exogenous hormonal stimulus if deprived of their enveloping follicular cells, a phenomenon called spontaneous maturation. In amphibian oocytes, numerous signalling mechanisms have been involved in the rapid, non-genomic, membrane effects of progesterone, but most of these are not fully understood.The data presented here demonstrate that activation of the Gαiprotein by Mas-7 induced maturation in non-competent oocytes and also an increase in GVBD (germinal vesicle breakdown) in competent oocytes. Similar results were obtained with intact follicles independent of the season. The activation of aden...
RESUMEN: Las leyes que rigen las instituciones de educación superior y el perfil del egresado de ... more RESUMEN: Las leyes que rigen las instituciones de educación superior y el perfil del egresado de la carrera de Bioquímica exigen la form ación de profesionales capaces de adaptarse a los cambios científicos-tecnológicos, c on alta capacidad de análisis, de interpretación y creatividad, capaces de actualizar se continuamente en conocimientos y tecnologías. Particularmente, la Cátedra de Histolo gía de la Facultad de Bioquímica (U.N.T.) detecta bajo rendimiento y desmotivación en sus alu mnos. Objetivos: Caracterizar el proceso de enseñanza-aprendizaje tr dicional – Identificar competencias profesionales ausentes Implementar e str tegias metodológicas que promuevan dichas competencias. Metodología: Fase de Diagnóstico: Se realizaron encuestas a alumnos que cursaron la asignatura, se complementaron con entrevistas a alu mnos y docentes Fase de Ejecución: Se planificaron e implementaron prácticas de enseñanza y evaluación superadoras. Se evaluaron los resultados mediante informe de un d...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the o... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which display an incomplete metamorphosis. We use Rhodnius prolixus as a convenient experimental model to test two hypotheses: (1) the role of neuropeptides that regulate ecdysis in Holometabola is conserved in hemimetabolous insects; and (2) the neuropeptides regulating ecdysis play a role in the regulation of female reproduction during the adult stage. The RNA interference-mediated reduction of ecdysis triggering hormone (ETH) mRNA levels in fourth-instar nymphs resulted in lethality at the expected time of...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the o... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which display an incomplete metamorphosis. We use Rhodnius prolixus as a convenient experimental model to test two hypotheses: (1) the role of neuropeptides that regulate ecdysis in Holometabola is conserved in hemimetabolous insects; and (2) the neuropeptides regulating ecdysis play a role in the regulation of female reproduction during the adult stage. The RNA interference-mediated reduction of ecdysis triggering hormone (ETH) mRNA levels in fourth-instar nymphs resulted in lethality at the expected time of...
SummaryEgg activation, which includes cortical granule exocytosis, resumption and completion of m... more SummaryEgg activation, which includes cortical granule exocytosis, resumption and completion of meiosis and pronuclear formation culminates in the first mitotic cleavage. However, the mechanism through which the fertilizing sperm induces this phenomenon is still controversial. We investigated the effect of the microinjection of homologous sperm soluble fractions obtained by fast protein liquid chromatography (FPLC) from reacted sperm (without acrosome) and non-reacted sperm on the activation of Rhinella arenarum oocytes matured in vitro. The FPLC-purified sperm fraction obtained from reacted or non-reacted sperm is able to induce oocyte activation when it is microinjected. This fraction has a 24 kDa protein and showed phospholipase C (PLC) activity in vitro, which was inhibited by D-609 but not by n-butanol or neomycin, suggesting that it is a PLC that is specific for phosphatidylcholine (PC-PLC). The assays conducted using inhibitors of inositol triphosphate (IP3) and ryanodine rec...
SummaryDuring activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastr... more SummaryDuring activation of amphibian eggs, cortical granule exocytosis causes elaborate ultrastructural changes in the vitelline envelope. These changes involve modifications in the structure of the vitelline envelope and formation of a fertilization envelope (FE) that can no longer be penetrated by sperm. In Bufo arenarum, as the egg traverses the oviduct, the vitelline envelope is altered by a trypsin-like protease secreted by the oviduct, which induces an increased susceptibility of the vitelline envelope to sperm lysins. Full-grown oocytes of B. arenarum, matured in vitro by progesterone, are polyspermic, although cortical granule exocytosis seems to occur within a normal chronological sequence. These oocytes can be fertilized with or without trypsin treatment, suggesting that the vitelline envelope is totally sperm-permeable. Vitelline envelopes without trypsin treatment cannot retain either gp90 or gp96. This suggests that these glycoproteins are involved in the block to poly...
SummaryIn the fertilization of most animals, egg activation is accompanied by an increase in cyto... more SummaryIn the fertilization of most animals, egg activation is accompanied by an increase in cytoplasmatic Ca2+; however, the mechanism through which the fertilizing sperm induce this phenomenon is still controversial. An increase in intracellular free Ca2+is required to trigger egg activation events, a process that includes cortical granule exocytosis, resumption and completion of meiosis and DNA replication, and culminates in the first mitotic cleavage. In this work, we investigated the effect of microinjection and incubation of different fractions of homologous sperm extract on the activation ofBufo arenarumoocytes maturedin vitro. Two heat treatment-sensitive fractions obtained by chromatography were able to induce oocyte activation. The sperm fraction, which contained a 24 kDa protein, induced 90% activation when it was microinjected into the oocytes. Whilst the sperm fraction, which contained a 36 kDa protein, was able to induce about 70% activation only when it was applied on...
In ecdysozoan animals, moulting entails the production of a new exoskeleton and the shedding of t... more In ecdysozoan animals, moulting entails the production of a new exoskeleton and the shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and activates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little functional information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which displays an incomplete metamorphosis.Here, we studied neuropeptides related to ecdysis regulation in the hemi-metabolous insect Rhodnius prolixus. The RNA interference-mediated reduction of ETH expression in fourth instar nymphs resulted in lethality at the expected time of ecdysis, thereby showing its crucial role in this process. Furthermore, the results revealed the involvement of ETH in the regulation of reproductive fitness. Different from holometabolous, the knockdown of ETH in adult females l...
Abstract We examined the histological structure of 8 skin areas thought to contain cutaneous glan... more Abstract We examined the histological structure of 8 skin areas thought to contain cutaneous glands of potential importance in scent communication in 16 brown brocket deerMazama gouazoubira Fisher, 1814, using standard histological techniques. Frontal areas and ...
Uploads
Papers by María Teresa Ajmat