The document discusses a study that measured ion currents in bovine spermatozoa using patch-clamping. It found an outwardly rectifying potassium current sensitive to changes in potassium concentration and tetraethylammonium. Application of venom from the Chilean black widow spider blocked this potassium current, altered the passive properties of the plasma membrane, and caused calcium influx. This was reflected by changes in basal fluorescent units and a reduction in membrane conductance, as calcium channels opened in a voltage-dependent manner. The study suggests the venom affects ion channels in sperm cells.
1. This study examined the effects of insulin on adenosine transport in human umbilical artery smooth muscle cells from normal pregnancies and those with gestational diabetes.
2. Insulin increased adenosine transport in cells from normal pregnancies by increasing nitric oxide and cGMP levels. However, insulin decreased the already elevated adenosine transport in cells from diabetic pregnancies by activating adenylyl cyclase.
3. The results suggest that insulin differentially modulates adenosine transport in these cell types, and that adenosine signaling may be altered under conditions of sustained hyperglycemia in diabetes.
This document summarizes research on the role of calcium and motility in sperm cell viability and function. It discusses how calcium regulates flagellar movement and capacitation processes like the acrosome reaction. Maintaining low motility through modulating calcium channels may increase sperm cell viability by reducing reactive oxygen species production from flagellar activity. The document also reviews various ion channels involved in calcium signaling in sperm and how environmental factors like temperature can impact sperm cell physiology and preservation.
The venom of the Chilean spider Latrodectus mactans was found to have effects on several ion currents in Xenopus laevis oocytes. Specifically, it was found to:
1) Make the resting membrane potential more negative, potentially by closing one or more ion conductances.
2) Primarily affect a transient outward potassium current, likely mediated by a Kv channel homologous to shaker, reducing this current.
3) Have no effect on calcium-dependent chloride currents activated through the lysophosphatidic acid receptor or on voltage- and calcium-activated chloride currents.
Este documento compara la motilidad y viabilidad de espermatozoides de mamíferos y peces. Analiza parámetros como la motilidad, acrosoma, calcio intracelular y viabilidad de espermatozoides bajo diferentes condiciones como refrigeración, activación y envejecimiento. Los resultados muestran que la regulación del calcio intracelular es fundamental para el movimiento y función de los espermatozoides en estas especies.
This document summarizes research on sperm cell motility, viability, and calcium regulation. It discusses how sperm motility is regulated by calcium levels, which are controlled by ion channels such as CATsper. Modulating calcium channels and reducing motility may increase sperm cell viability by decreasing reactive oxygen species production. The document also reviews the roles of factors like temperature, membrane potential, and ion currents in modulating calcium concentrations and sperm cell functions like capacitation and the acrosome reaction.
Este documento describe un estudio in vitro de Didymo realizado en el Laboratorio de Fisiología de la Reproducción de la Universidad Católica de Temuco. El estudio utilizó microscopía de campo claro, Nomarsky y confocal para observar Didymo en condiciones de control a 38°C y después de 30 minutos, 24 horas, congelación y almacenamiento seco durante 1 y 2 meses. El resumen discute la viabilidad de Didymo basada en la presencia de granulos llenos o vacíos y propone el uso de un protocolo
Navarrete et al 2010 veneno y espermiosJorge Parodi
The document summarizes research on the effects of venom from the Chilean black widow spider (Latrodectus mactans) on bovine spermatozoa. The venom was found to increase intracellular calcium levels in the spermatozoa by blocking potassium channels, leading to plasma membrane depolarization. This induced calcium influx and triggered the acrosome reaction in over 40% of cells. However, the venom did not affect sperm morphology, DNA stability, or cause toxicity at the concentrations tested. The results suggest the venom alters sperm function by modulating membrane potential and calcium dynamics.
Perusahaan Jagex didirikan pada tahun 1999 oleh Andrew dan Paul Gower untuk mengembangkan game Java. Pada tahun 2001, mereka meluncurkan game MMORPG Runescape yang populer. Jagex terus berkembang dengan merilis konten baru untuk Runescape dan layanan seperti FunOrb serta mengembangkan game baru seperti Stellar Dawn. Jagex saat ini memiliki ratusan karyawan dan terus berkembang menjadi salah satu pengembang game terbesar asal In
1. This study examined the effects of insulin on adenosine transport in human umbilical artery smooth muscle cells from normal pregnancies and those with gestational diabetes.
2. Insulin increased adenosine transport in cells from normal pregnancies by increasing nitric oxide and cGMP levels. However, insulin decreased the already elevated adenosine transport in cells from diabetic pregnancies by activating adenylyl cyclase.
3. The results suggest that insulin differentially modulates adenosine transport in these cell types, and that adenosine signaling may be altered under conditions of sustained hyperglycemia in diabetes.
This document summarizes research on the role of calcium and motility in sperm cell viability and function. It discusses how calcium regulates flagellar movement and capacitation processes like the acrosome reaction. Maintaining low motility through modulating calcium channels may increase sperm cell viability by reducing reactive oxygen species production from flagellar activity. The document also reviews various ion channels involved in calcium signaling in sperm and how environmental factors like temperature can impact sperm cell physiology and preservation.
The venom of the Chilean spider Latrodectus mactans was found to have effects on several ion currents in Xenopus laevis oocytes. Specifically, it was found to:
1) Make the resting membrane potential more negative, potentially by closing one or more ion conductances.
2) Primarily affect a transient outward potassium current, likely mediated by a Kv channel homologous to shaker, reducing this current.
3) Have no effect on calcium-dependent chloride currents activated through the lysophosphatidic acid receptor or on voltage- and calcium-activated chloride currents.
Este documento compara la motilidad y viabilidad de espermatozoides de mamíferos y peces. Analiza parámetros como la motilidad, acrosoma, calcio intracelular y viabilidad de espermatozoides bajo diferentes condiciones como refrigeración, activación y envejecimiento. Los resultados muestran que la regulación del calcio intracelular es fundamental para el movimiento y función de los espermatozoides en estas especies.
This document summarizes research on sperm cell motility, viability, and calcium regulation. It discusses how sperm motility is regulated by calcium levels, which are controlled by ion channels such as CATsper. Modulating calcium channels and reducing motility may increase sperm cell viability by decreasing reactive oxygen species production. The document also reviews the roles of factors like temperature, membrane potential, and ion currents in modulating calcium concentrations and sperm cell functions like capacitation and the acrosome reaction.
Este documento describe un estudio in vitro de Didymo realizado en el Laboratorio de Fisiología de la Reproducción de la Universidad Católica de Temuco. El estudio utilizó microscopía de campo claro, Nomarsky y confocal para observar Didymo en condiciones de control a 38°C y después de 30 minutos, 24 horas, congelación y almacenamiento seco durante 1 y 2 meses. El resumen discute la viabilidad de Didymo basada en la presencia de granulos llenos o vacíos y propone el uso de un protocolo
Navarrete et al 2010 veneno y espermiosJorge Parodi
The document summarizes research on the effects of venom from the Chilean black widow spider (Latrodectus mactans) on bovine spermatozoa. The venom was found to increase intracellular calcium levels in the spermatozoa by blocking potassium channels, leading to plasma membrane depolarization. This induced calcium influx and triggered the acrosome reaction in over 40% of cells. However, the venom did not affect sperm morphology, DNA stability, or cause toxicity at the concentrations tested. The results suggest the venom alters sperm function by modulating membrane potential and calcium dynamics.
Perusahaan Jagex didirikan pada tahun 1999 oleh Andrew dan Paul Gower untuk mengembangkan game Java. Pada tahun 2001, mereka meluncurkan game MMORPG Runescape yang populer. Jagex terus berkembang dengan merilis konten baru untuk Runescape dan layanan seperti FunOrb serta mengembangkan game baru seperti Stellar Dawn. Jagex saat ini memiliki ratusan karyawan dan terus berkembang menjadi salah satu pengembang game terbesar asal In
1) Xenopus laevis oocytes exposed to amyloid-β aggregate developed oscillatory electric activity (blips) recorded via two-microelectrode voltage clamp.
2) The blips increased in amplitude over time from 3.8 nA initially to 6.8 nA after 15 minutes of amyloid-β aggregate exposure, similar to the effects of channel-forming agents amphotericin B and gramicidin.
3) The amyloid-β aggregate-induced currents were dependent on extracellular calcium and disrupted calcium-dependent currents between oocytes and surrounding follicular cells. Electron microscopy also revealed dissociation of follicular cells from the oocytes.
This study investigated whether S-methylcysteine (SMC), a metabolite of monohalomethanes, contributes to their neurotoxicity. The researchers found that:
1) High concentrations of SMC (10-2 M) reduced synaptic responses in hippocampal slices, an effect that was partially reversible.
2) In organotypic hippocampal cultures, 24 hour exposure to 5x10-5 M SMC compromised membrane integrity in the dentate gyrus, while lower concentrations increased population spike amplitudes and repetitive discharges without affecting membrane integrity.
3) In dissociated hippocampal neurons, SMC reduced GABA-induced currents, acting as a competitive GABAA receptor antagonist with
The document discusses alternative treatments and therapies for Alzheimer's disease, including herbal medicines, supplements, and clinical trials. It summarizes several studies that tested supplements like ginkgo biloba, omega-3 fatty acids, and phosphatidylserine against placebos but found no reduction in cognitive decline. Another study showed that continued treatment with donepezil provided cognitive and functional benefits over 12 months for patients with moderate to severe Alzheimer's. The document acknowledges further research is still needed to understand alternative treatments for Alzheimer's disease.
The internet has profoundly affected how we collect and consume information; there is no debate about that. How can media companies adapt, survive and thrive in the digital age by returning to the fundamentals of the narrative?
Tetrahydrohyperforin (IDN5706), a derivative of the active molecule hyperforin in St. John's Wort, was examined for its ability to prevent cognitive deficits and synaptic impairment in an Alzheimer's disease mouse model. Five-month old APPswe/PSEN1DE9 mice were treated with IDN5706 for 10 weeks. IDN5706 improved memory, prevented decreases in synaptic proteins and LTP, and reduced amyloid-beta plaque burden, tau hyperphosphorylation, and astrogliosis. In cell cultures, IDN5706 decreased amyloid precursor protein processing leading to amyloid-beta peptide generation. The results suggest IDN5706 may be a potential therapeutic for treating Alzheimer's
1) Wnt3a protein rapidly increases the frequency of miniature excitatory synaptic currents in hippocampal neurons through a mechanism involving calcium influx and post-translational modifications enhancing vesicle exocytosis.
2) While previous studies suggested Wnt signaling modulates neurotransmission, this is the first to demonstrate a direct effect of a purified Wnt ligand, Wnt3a, on synaptic transmission.
3) The results identify Wnt3a and its receptor LRP6 as key molecules in neurotransmission modulation and suggest crosstalk between canonical and Wnt/calcium signaling in central neurons.
This study investigated how elevated glucose levels affect adenosine transport in human umbilical vein endothelial cells (HUVECs). The researchers found that incubating HUVECs in 25 mmol/L glucose or ATP reduced adenosine transport by inhibiting the human equilibrative nucleoside transporter 1 (hENT1). This inhibition was mediated by activation of P2Y2 purinoceptors and involved reduced hENT1 expression and activity. The effects of glucose and nucleotides were blocked by P2Y receptor antagonists, demonstrating that glucose stimulates P2Y2 receptors by increasing ATP release, providing a potential mechanism for how glucose impacts adenosine regulation and vascular function.
The document discusses reactive oxygen species (ROS) and their effects on boar sperm physiology. It notes that ROS can negatively impact sperm motility, viability, and fertilization potential by damaging lipids, proteins, DNA, and inducing premature capacitation. This is detrimental to sperm quality and lifespan. The document also examines the use of seminal fluid diluents for short or long-term sperm preservation. Diluents aim to maintain sperm concentration and viability during storage and transport. However, ROS levels may still increase and damage sperm over time. The inclusion of macromolecules that stabilize sperm membranes could help protect sperm from ROS effects and better maintain motility and function during preservation.
The document discusses interpersonal skills and their importance in organizations. It identifies four main components of interpersonal skills: self-awareness, self-management, social awareness, and social skills. It then provides further explanation and examples of self-awareness and self-regulation, which are described as key aspects of being a leader. Effective interpersonal skills such as self-awareness, self-management, and social skills are important for cooperation, trust and effectiveness in organizations.
Bagaimana cara membuat mesin penetas telur sederhanaSurya Tangguh
Teks tersebut menjelaskan cara membuat mesin penetas telur sederhana dengan bahan-bahan yang mudah didapatkan seperti kayu, triplek, kawat, dan lampu pijar sebagai sumber panas. Mesin ini dapat digunakan untuk menetaskan telur ayam, bebek, atau puyuh dengan biaya rendah. Langkah-langkah pembuatannya meliputi pembuatan kerangka dari kayu dan triplek, penambahan rak dan lampu pemanas, serta
Optical nanosensors called PEBBLEs (Probe Encapsulated By Biologically Localized Embedding) are nano-scale sensing devices that encapsulate analyte-specific dyes inside a biologically inert matrix for quantitative measurements inside cells. PEBBLEs come in four types of matrices and can be delivered into cells via four methods. They work by either directly measuring ions and small molecules using fluorescent indicators, or using ion correlation with a silent ionophore and chromoionophore to indicate changes in pH. PEBBLEs protect cells from dyes and dyes from cellular interference while enabling rapid, minimally invasive intracellular measurements of ions and molecules.
In tech perforated-patch_clamp_in_non_neuronal_cells_the_model_of_mammalian_s...Jorge Parodi
This document outlines the steps to perform perforated patch-clamp recordings on mammalian sperm cells. It describes how perforated patch-clamp allows for better preservation of the intracellular environment compared to whole-cell recordings. The key steps include selecting motile sperm cells using a swim-up method, incubating the cells in a hyposmotic solution, and applying nystatin or other drugs in the recording pipette to gradually form holes in the plasma membrane. With practice, tight seals of over 1 GΩ can be obtained in about 45% of attempts, allowing recordings of ion channel currents in the sperm cell membrane.
The document summarizes a study that investigated the effects of low molecular weight components from the venom of the Chilean Black Widow spider (Latrodectus mactans) on synaptic activity. Whole-cell patch clamp techniques were used to study the effects of purified venom on rat hippocampal neuronal cultures. The venom increased neuronal membrane resistance, prolonged action potentials, and increased spontaneous synaptic activity in a concentration- and time-dependent manner. This demonstrates that the venom has pharmacological effects through low molecular weight fragments, despite L. mactans venom not containing alpha-latrotoxin like the European Black Widow spider venom.
Since the 1970s, there have been studies of the venom of Latrodectus spiders, particularly the latrotoxin (LTX) from Latrodectus mactans. Many studies aimed to understand how the venom affects the muscular system. It is now accepted that LTX can generate calcium-permeable membrane pores and modulate synaptic vesicle release. Interestingly, when work began with venom from Latrodectus spiders in Chile, it produced similar clinical effects to bites from this spider elsewhere, though with differing intensities. The purpose of early studies was to understand the systemic mechanisms of this venom and explore other active compounds of biological interest. It was found that these molecules can cause systemic effects like muscle contraction changes; generate
Extension of Life-Span by Introduction of Telomerase into Normal Human CellsATMB
Expression of telomerase was introduced into normal human cells. This extended the life span of the cells by preventing telomere shortening. Two constructs expressing the catalytic subunit of telomerase (hTRT) were tested. Cells with ectopic hTRT expression showed telomerase activity and prolonged proliferation compared to controls. The results indicate telomere shortening limits cell divisions in the absence of telomerase and low levels are insufficient to prevent shortening over time.
Here are the key changes that occur inside cells as a result of alterations in the amount of calcium in the cytoplasm:
- Calcium acts as a secondary messenger that triggers many cellular processes. Increased cytoplasmic calcium levels activate calcium-dependent proteins and enzymes.
- Higher calcium levels cause contraction of muscle cells through activation of the contractile proteins actin and myosin. This is how muscles contract in response to neural signals.
- Increased calcium also triggers the release of neurotransmitters from neurons at synapses. This allows neurons to communicate via electrical and chemical signals.
- In non-muscle cells, calcium signals activation of various intracellular pathways involved in processes like cell migration, gene expression, and apoptosis (programmed cell death
This article examines the cytotoxic effects of perezone and its isomer isoperezone on human leukemia cells. The key findings are:
1. Both perezone and isoperezone induce cytotoxicity in a concentration-dependent manner through both caspase-dependent and caspase-independent mechanisms.
2. The compounds cause changes in cell size, granularity, phosphatidylserine translocation, mitochondrial membrane potential disruption, and do not induce apoptosis inducing factor.
3. Perezone showed greater cytotoxic effects than isoperezone, but the mechanisms of cell death induction differed between the two compounds depending on concentration.
The document discusses a seminar presentation about electromagnetic resonance and its applications in various fields including chemistry, biology, medicine, materials science, anthropology, and physics. It describes several techniques involving electromagnetic resonance, including nuclear magnetic resonance (NMR), electron paramagnetic resonance, magnetic resonance imaging, and superconducting quantum interference devices. The presentation proposes using electromagnetic resonance techniques to observe the behavior of proteins during active transport through cell membranes, which could provide insight into protein function, drug interactions, and viral infections.
This document discusses the development of an ex vivo model to study the effects of Didymosphenia geminata, commonly known as rock snot, on freshwater fish cells and gametes. It first reviews D. geminata as an invasive nuisance species found in rivers internationally. It then describes preliminary work maintaining D. geminata in an artificial river system and observing effects on cell lines. The document proposes building upon this to explore chronic effects of contaminated water and extracts on cells. It also reviews maintaining D. geminata viability in the lab and the need for a complete river model to better understand its growth requirements and impacts on aquatic systems.
1) The study developed a low-cost screening system using freely available ImageJ software to analyze video recordings of the swimming behavior and kinetics of different life stages of the sea louse Caligus rogercresseyi exposed to potential drug compounds.
2) Results showed that taurine, glutamate, GABA, and iodine all impacted the motility of C. rogercresseyi planktonic forms in a time- and dose-dependent manner, with iodine having the strongest inhibiting effects.
3) The system provides a way to efficiently and inexpensively study the pharmacological effects of potential treatments on C. rogercresseyi before conducting more complex in vitro
Tipos de modelos de cultivos celulares iiJorge Parodi
Este documento describe los diferentes tipos de modelos de cultivos celulares, incluyendo cultivos primarios, subcultivos, líneas celulares, explantes, cultivos de órganos, cultivos organotípicos y cultivos tridimensionales. Explica que cada modelo mantiene algunas propiedades fisiológicas y morfológicas pero pierde propiedades estructurales con el tiempo, y que los modelos más avanzados como los cultivos organotípicos requieren múltiples tipos de células. También resume algunas aplicaciones generales
1) Xenopus laevis oocytes exposed to amyloid-β aggregate developed oscillatory electric activity (blips) recorded via two-microelectrode voltage clamp.
2) The blips increased in amplitude over time from 3.8 nA initially to 6.8 nA after 15 minutes of amyloid-β aggregate exposure, similar to the effects of channel-forming agents amphotericin B and gramicidin.
3) The amyloid-β aggregate-induced currents were dependent on extracellular calcium and disrupted calcium-dependent currents between oocytes and surrounding follicular cells. Electron microscopy also revealed dissociation of follicular cells from the oocytes.
This study investigated whether S-methylcysteine (SMC), a metabolite of monohalomethanes, contributes to their neurotoxicity. The researchers found that:
1) High concentrations of SMC (10-2 M) reduced synaptic responses in hippocampal slices, an effect that was partially reversible.
2) In organotypic hippocampal cultures, 24 hour exposure to 5x10-5 M SMC compromised membrane integrity in the dentate gyrus, while lower concentrations increased population spike amplitudes and repetitive discharges without affecting membrane integrity.
3) In dissociated hippocampal neurons, SMC reduced GABA-induced currents, acting as a competitive GABAA receptor antagonist with
The document discusses alternative treatments and therapies for Alzheimer's disease, including herbal medicines, supplements, and clinical trials. It summarizes several studies that tested supplements like ginkgo biloba, omega-3 fatty acids, and phosphatidylserine against placebos but found no reduction in cognitive decline. Another study showed that continued treatment with donepezil provided cognitive and functional benefits over 12 months for patients with moderate to severe Alzheimer's. The document acknowledges further research is still needed to understand alternative treatments for Alzheimer's disease.
The internet has profoundly affected how we collect and consume information; there is no debate about that. How can media companies adapt, survive and thrive in the digital age by returning to the fundamentals of the narrative?
Tetrahydrohyperforin (IDN5706), a derivative of the active molecule hyperforin in St. John's Wort, was examined for its ability to prevent cognitive deficits and synaptic impairment in an Alzheimer's disease mouse model. Five-month old APPswe/PSEN1DE9 mice were treated with IDN5706 for 10 weeks. IDN5706 improved memory, prevented decreases in synaptic proteins and LTP, and reduced amyloid-beta plaque burden, tau hyperphosphorylation, and astrogliosis. In cell cultures, IDN5706 decreased amyloid precursor protein processing leading to amyloid-beta peptide generation. The results suggest IDN5706 may be a potential therapeutic for treating Alzheimer's
1) Wnt3a protein rapidly increases the frequency of miniature excitatory synaptic currents in hippocampal neurons through a mechanism involving calcium influx and post-translational modifications enhancing vesicle exocytosis.
2) While previous studies suggested Wnt signaling modulates neurotransmission, this is the first to demonstrate a direct effect of a purified Wnt ligand, Wnt3a, on synaptic transmission.
3) The results identify Wnt3a and its receptor LRP6 as key molecules in neurotransmission modulation and suggest crosstalk between canonical and Wnt/calcium signaling in central neurons.
This study investigated how elevated glucose levels affect adenosine transport in human umbilical vein endothelial cells (HUVECs). The researchers found that incubating HUVECs in 25 mmol/L glucose or ATP reduced adenosine transport by inhibiting the human equilibrative nucleoside transporter 1 (hENT1). This inhibition was mediated by activation of P2Y2 purinoceptors and involved reduced hENT1 expression and activity. The effects of glucose and nucleotides were blocked by P2Y receptor antagonists, demonstrating that glucose stimulates P2Y2 receptors by increasing ATP release, providing a potential mechanism for how glucose impacts adenosine regulation and vascular function.
The document discusses reactive oxygen species (ROS) and their effects on boar sperm physiology. It notes that ROS can negatively impact sperm motility, viability, and fertilization potential by damaging lipids, proteins, DNA, and inducing premature capacitation. This is detrimental to sperm quality and lifespan. The document also examines the use of seminal fluid diluents for short or long-term sperm preservation. Diluents aim to maintain sperm concentration and viability during storage and transport. However, ROS levels may still increase and damage sperm over time. The inclusion of macromolecules that stabilize sperm membranes could help protect sperm from ROS effects and better maintain motility and function during preservation.
The document discusses interpersonal skills and their importance in organizations. It identifies four main components of interpersonal skills: self-awareness, self-management, social awareness, and social skills. It then provides further explanation and examples of self-awareness and self-regulation, which are described as key aspects of being a leader. Effective interpersonal skills such as self-awareness, self-management, and social skills are important for cooperation, trust and effectiveness in organizations.
Bagaimana cara membuat mesin penetas telur sederhanaSurya Tangguh
Teks tersebut menjelaskan cara membuat mesin penetas telur sederhana dengan bahan-bahan yang mudah didapatkan seperti kayu, triplek, kawat, dan lampu pijar sebagai sumber panas. Mesin ini dapat digunakan untuk menetaskan telur ayam, bebek, atau puyuh dengan biaya rendah. Langkah-langkah pembuatannya meliputi pembuatan kerangka dari kayu dan triplek, penambahan rak dan lampu pemanas, serta
Optical nanosensors called PEBBLEs (Probe Encapsulated By Biologically Localized Embedding) are nano-scale sensing devices that encapsulate analyte-specific dyes inside a biologically inert matrix for quantitative measurements inside cells. PEBBLEs come in four types of matrices and can be delivered into cells via four methods. They work by either directly measuring ions and small molecules using fluorescent indicators, or using ion correlation with a silent ionophore and chromoionophore to indicate changes in pH. PEBBLEs protect cells from dyes and dyes from cellular interference while enabling rapid, minimally invasive intracellular measurements of ions and molecules.
In tech perforated-patch_clamp_in_non_neuronal_cells_the_model_of_mammalian_s...Jorge Parodi
This document outlines the steps to perform perforated patch-clamp recordings on mammalian sperm cells. It describes how perforated patch-clamp allows for better preservation of the intracellular environment compared to whole-cell recordings. The key steps include selecting motile sperm cells using a swim-up method, incubating the cells in a hyposmotic solution, and applying nystatin or other drugs in the recording pipette to gradually form holes in the plasma membrane. With practice, tight seals of over 1 GΩ can be obtained in about 45% of attempts, allowing recordings of ion channel currents in the sperm cell membrane.
The document summarizes a study that investigated the effects of low molecular weight components from the venom of the Chilean Black Widow spider (Latrodectus mactans) on synaptic activity. Whole-cell patch clamp techniques were used to study the effects of purified venom on rat hippocampal neuronal cultures. The venom increased neuronal membrane resistance, prolonged action potentials, and increased spontaneous synaptic activity in a concentration- and time-dependent manner. This demonstrates that the venom has pharmacological effects through low molecular weight fragments, despite L. mactans venom not containing alpha-latrotoxin like the European Black Widow spider venom.
Since the 1970s, there have been studies of the venom of Latrodectus spiders, particularly the latrotoxin (LTX) from Latrodectus mactans. Many studies aimed to understand how the venom affects the muscular system. It is now accepted that LTX can generate calcium-permeable membrane pores and modulate synaptic vesicle release. Interestingly, when work began with venom from Latrodectus spiders in Chile, it produced similar clinical effects to bites from this spider elsewhere, though with differing intensities. The purpose of early studies was to understand the systemic mechanisms of this venom and explore other active compounds of biological interest. It was found that these molecules can cause systemic effects like muscle contraction changes; generate
Extension of Life-Span by Introduction of Telomerase into Normal Human CellsATMB
Expression of telomerase was introduced into normal human cells. This extended the life span of the cells by preventing telomere shortening. Two constructs expressing the catalytic subunit of telomerase (hTRT) were tested. Cells with ectopic hTRT expression showed telomerase activity and prolonged proliferation compared to controls. The results indicate telomere shortening limits cell divisions in the absence of telomerase and low levels are insufficient to prevent shortening over time.
Here are the key changes that occur inside cells as a result of alterations in the amount of calcium in the cytoplasm:
- Calcium acts as a secondary messenger that triggers many cellular processes. Increased cytoplasmic calcium levels activate calcium-dependent proteins and enzymes.
- Higher calcium levels cause contraction of muscle cells through activation of the contractile proteins actin and myosin. This is how muscles contract in response to neural signals.
- Increased calcium also triggers the release of neurotransmitters from neurons at synapses. This allows neurons to communicate via electrical and chemical signals.
- In non-muscle cells, calcium signals activation of various intracellular pathways involved in processes like cell migration, gene expression, and apoptosis (programmed cell death
This article examines the cytotoxic effects of perezone and its isomer isoperezone on human leukemia cells. The key findings are:
1. Both perezone and isoperezone induce cytotoxicity in a concentration-dependent manner through both caspase-dependent and caspase-independent mechanisms.
2. The compounds cause changes in cell size, granularity, phosphatidylserine translocation, mitochondrial membrane potential disruption, and do not induce apoptosis inducing factor.
3. Perezone showed greater cytotoxic effects than isoperezone, but the mechanisms of cell death induction differed between the two compounds depending on concentration.
The document discusses a seminar presentation about electromagnetic resonance and its applications in various fields including chemistry, biology, medicine, materials science, anthropology, and physics. It describes several techniques involving electromagnetic resonance, including nuclear magnetic resonance (NMR), electron paramagnetic resonance, magnetic resonance imaging, and superconducting quantum interference devices. The presentation proposes using electromagnetic resonance techniques to observe the behavior of proteins during active transport through cell membranes, which could provide insight into protein function, drug interactions, and viral infections.
Similar to Parodi et al 2010 potasio espermios (8)
This document discusses the development of an ex vivo model to study the effects of Didymosphenia geminata, commonly known as rock snot, on freshwater fish cells and gametes. It first reviews D. geminata as an invasive nuisance species found in rivers internationally. It then describes preliminary work maintaining D. geminata in an artificial river system and observing effects on cell lines. The document proposes building upon this to explore chronic effects of contaminated water and extracts on cells. It also reviews maintaining D. geminata viability in the lab and the need for a complete river model to better understand its growth requirements and impacts on aquatic systems.
1) The study developed a low-cost screening system using freely available ImageJ software to analyze video recordings of the swimming behavior and kinetics of different life stages of the sea louse Caligus rogercresseyi exposed to potential drug compounds.
2) Results showed that taurine, glutamate, GABA, and iodine all impacted the motility of C. rogercresseyi planktonic forms in a time- and dose-dependent manner, with iodine having the strongest inhibiting effects.
3) The system provides a way to efficiently and inexpensively study the pharmacological effects of potential treatments on C. rogercresseyi before conducting more complex in vitro
Tipos de modelos de cultivos celulares iiJorge Parodi
Este documento describe los diferentes tipos de modelos de cultivos celulares, incluyendo cultivos primarios, subcultivos, líneas celulares, explantes, cultivos de órganos, cultivos organotípicos y cultivos tridimensionales. Explica que cada modelo mantiene algunas propiedades fisiológicas y morfológicas pero pierde propiedades estructurales con el tiempo, y que los modelos más avanzados como los cultivos organotípicos requieren múltiples tipos de células. También resume algunas aplicaciones generales
Dolores de la industria salmonicultura en chile vJorge Parodi
El documento discute varias enfermedades que afectan a la salmonicultura en Chile. La septicemia rickettsial salmonidea (SRS), causada por la bacteria Piscirickettsia salmonis, es el principal problema y se transmite horizontalmente. Otras enfermedades importantes son la enfermedad del riñón del salmón y la tenacibaculosis. Se ha observado una disminución de SRS del 30% en 2018, pero ha aumentado la caligidosis. Más investigación es necesaria sobre la patología y transmisión de la tenacibaculosis.
Este documento compara la motilidad y viabilidad de espermatozoides de mamíferos y peces usando diferentes modelos. Analiza parámetros como la motilidad, acrosoma, ondas de calcio y viabilidad de espermatozoides bajo diferentes condiciones como refrigeración, activación y envejecimiento. También estudia el efecto de xenobióticos como el didymo en estos parámetros. Los resultados sugieren que la regulación del calcio intracelular es importante para el funcionamiento normal de los espermatozoides.
Algo nuevo, algo viejo y algo prestado en alzheimer 2014 jparodiJorge Parodi
Este documento presenta una revisión de diferentes enfoques para comprender la enfermedad de Alzheimer, incluyendo la hipótesis del "poro amiloide", estudios sobre el efecto del etanol en agregados de beta-amiloide, y experimentos en ovocitos de rana para analizar la actividad sináptica. También resume diferentes estudios sobre los mecanismos por los cuales los agregados de beta-amiloide podrían inducir disfunción sináptica y neurodegeneración.
Este documento presenta una revisión de diferentes enfoques para comprender la enfermedad de Alzheimer, incluyendo la hipótesis del "poro amiloide", estudios sobre el efecto del etanol en agregados de beta-amiloide, y experimentos en ovocitos de rana para analizar la actividad sináptica. También resume diferentes estudios sobre los mecanismos por los cuales los agregados de beta-amiloide podrían inducir disfunción sináptica y neurodegeneración.
IDN5706 is a semi-synthetic derivative of hyperforin that has neuroprotective effects. The document reports on experiments examining the effects of IDN5706 on field excitatory postsynaptic potentials (fEPSPs) in mouse hippocampal slices. The results suggest that IDN5706 activates TRPC3/6/7 channels, improving synaptic response and protecting against reductions in fEPSPs caused by amyloid beta oligomers. IDN5706 also improved spatial memory in mice, and this effect was blocked by a TRPC channel blocker. Computational modeling further supported the idea that IDN5706 activates TRPC channels.
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Parodi et al 2010 potasio espermios
1. Systems Biology in Reproductive Medicine, 56:37–43, 2010
Copyright & Informa Healthcare USA, Inc.
ISSN: 1939-6368 print/1939-6376 online
DOI: 10.3109/19396360903497217
Research Communication
+
Tetraethylammonium-Sensitive K Current
in the Bovine Spermatozoa and its
Blocking by the Venom of the Chilean
Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
Latrodectus mactans
Jorge Parodi,
Patricia Navarrete,
The morphology and size of spermatozoa hinder the study of the functional
Marcelo Marconi,
´ ´ ´
Raul Sanchez Gutierrez, properties of the spermatozoa plasma membrane. However, some studies have
´ ´
Ataulfo Martınez-Torres, and revealed the presence of a number of ion channels in this cell. We set out to
Fernando Romero Mejıas ´ measure the endogenous currents and to study the effect of the venom of the
Centro de neurociencia y Chilean black widow spider (Latrodectus mactans). By patch-clamping bovine
For personal use only.
´
Biologia de peptidos-BIOREN, spermatozoa our results indicate the presence of an outwardly rectifying
Departamento de Ciencias
current, sensitive to changes in K + concentration (30–140 mM) and to tetra-
´
Preclınicas, Facultad de
Medicina, Universidad de la
ethylammonium (TEA, 10–100 mM). The application of the venom (7.5 g/ml)
Frontera, Chile blocks these K+ currents and then alters the passive properties of the plasma
membrane. This leads to the entry of Ca ++ , reflected by a change in basal
´ ´
Ataulfo Martınez-Torres
fluorescent units (572 at 35710 FAU). The Ca ++ influx follows a reduction in
Laboratorio Neurobiologıa ´
Molecular y Celular II, the membrane conductance (control 2272; venom 1071 pS), as calcium
Departamento de Neurobiologıa ´ channels open in accord with voltage dependence.
Molecular y Celular, Instituto de
´
Neurobiologıa, Campus KEYWORDS ionic currents, Latrodectus venom, membrane potential, spermatozoa
´
Juriquilla-Queretaro, UNAM,
´
Mexico
INTRODUCTION
Abbreviations: TEA: tetraethyl-
ammonium; FAU: fluorescent arbitrary There is strong experimental evidence that mature mammalian sperma-
units; pS: membrane conductance; tozoa have several ionic-conductors, including those driven by voltage
CCVD: calcium channel voltage
dependent; PBS: phosphate saline dependent K + channels [Darszon et al. 1996; Labarca et al. 1995; Nuccitelli
buffer solution. and Ferguson 1994]. Recent reports using whole cell patch-clamping to
Received 13 August 2009; study ion-conductance, have described the functional properties of Ca ++
accepted 19 September 2009. channels (CATsper), which are key components of capacitation [Darszon
Address correspondence to et al. 2005; Wennemuth et al. 2000].
Jorge Parodi, Centro de Neuro-
´ ´
ciencias y Biologıa de Peptidos, The mammalian spermatozoa acquire the functional capacity to fertilize
´ ´
Nucleo cientıfico BIOREN, an egg during their trajectory along the female genital tract [Boni et al. 2007].
Universidad de la Frontera,
Montevideo 0870 Temuco, Chile. In this process the plasma membrane potential is hyperpolarized by the
E-mail: jparodi@ufro.cl activation of pH-sensitive K + -channels. This leads to an increase in Ca ++
37
2. permeability [Kumar et al. 2000; Linares-Hernandez with sensicam, for time lapse assessment with fast
et al. 1998; Shi and Ma 1998]. However, this increase perfusion of either venom or a high concentration of
of intracellular Ca ++ is not the sole cause of K + (30 mM). Notice the rise in fluorescence and the
capacitation, it has also been suggested that the immediate decrease of the emission after a few s as
intracellular pH and transient plasma membrane measured by its change in the midpiece. The
depolarization play a role [Fraire-Zamora and fluorometric data is summarized in Figure 1D
Gonzalez-Martinez 2004; Neri-Vidaurri Pdel et al. showing that both venom and K + increased the
2006] similar to the series of events that occur in free Ca ++ up to 35 fluorescent arbitrary units (FAU)
somatic cells [Baker et al. 1973]. The detailed as compared to the uninduced control. Together this
mechanism that leads to spermatozoa capacitation data suggests that spermatozoa calcium increases
remains to be detailed. after depolarization or perfusion with venom.
In a previous report we described that the venom
of the Chilean black widow spider Latrodectus
mactans increased the concentration of intra- Patch-Clamping Reveals a TEA-
cellular Ca ++ in spermatozoa [Romero et al. 2007]. Sensitive K+ Current
Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
Furthermore, this venom is known to block the TEA-
Spermatozoa exhibits varied permeability to ions
sensitive K + currents in neurons [Parodi and Romero
reflecting several channels, including the voltage-
2008] as well as endogenous K + currents of Xenopus
sensitive K + and ÀCa ++ [Darszon et al. 2006]. As
laevis oocytes [Parodi et al. 2008]. To assess the effect
illustrated in Figure 2A, whole-cell patch-clamping
of this venom on the plasma membrane potential
of spermatozoa showed inward and outward cur-
of bovine spermatozoa we used the nystatine-
rents. P pulses that ranged between À100 mV to
perforated patch-clamp technique. The results that
+ 100 mV were more sensitive to 50 mM TEA. These
begin to dissect the molecular components of
currents are plotted as a current/ voltage curve (I/V)
capacitation are reported below.
For personal use only.
(Fig. 2B). The TEA-sensitivity of the outward current
is consistent with the presence of a voltage depen-
dent potassium channel (Kv channel; IUPHAR
classification). These channels are crucial towards
RESULTS
maintaining the plasma membrane potential
Exposure to Venom Increases Free [Gutman et al. 2003]. Increasing the concentration
Intracellular Calcium of extracellular K + shifted the equilibrium potential
to more negative values (Fig. 2C). This is in accord
It has been shown by spectrophotometry that
with that predicted by the Nerst’s equation (Fig. 2D
exposing spermatozoa to the venom of the Chilean
and Table 1) indicating that the current was due to
L. mactans leads to an increase in pH and free
K + TEA-sensitive channels.
intracellular Ca ++ [Romero et al. 2007]. To extend
these results we assessed the changes in the
intracellular Ca ++ by fluorometry and patch-clamp.
Venom Alters the TEA-Sensitive
The spermatozoa loaded with Fluo-3 is shown in
Figure 1A. As expected, the basal level of free
K+ Current
intracellular Ca ++ is low, with most of the cells Outwardly-rectifying currents were efficiently and
emitting some faint fluorescence. In contrast, reversibly blocked when the spermatozoa were
30 min after the addition of the venom, the number exposed to the venom (Fig. 3A). The changes in
of cells exhibiting fluorescence increased consider- membrane conductance are summarized in Figure 3B.
ably (Fig. 1B). This was consistently observed Venom reduces the membrane conductance from
even after 3 repetitions suggesting that sudden 2271 pS to approximately 1072 pS (Fig. 3B). In
depolarization of the plasma membrane may induce contrast upon exposure to venom, the membrane
similar effects. resistance changed from 200 mO712 to 800 mO723,
Figure 1C shows typical fluorescence traces of the suggesting an important change in the passive mem-
spermatozoa midpiece loaded with Fluo-3 acquired brane properties.
38 J. Parodi et al.
3. Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
For personal use only.
FIGURE 1 Venom-induced rise of intracellular Ca + + . Sample images of Fluo-3 AM loaded spermatozoa in the absence (A), or presence
(B) of total venom (7.5 mg/ml). (C), fluorometric records. (D), fluorescent arbitrary units (FAU) of spermatozoa in high K + (30 mM) or
venom (7.5 mg/ml); the bars represent means7 SD of three different experiments. Calibration bar ¼ 5 mm.
We explored whether venom also modulates expected the pre-pulse currents were approximately
spermatozoa K + currents by increasing the free 300% higher than the control. Interestingly, 10 mM
intracellular Ca ++ as known to occur in somatic cells TEA did not affect the current.
[Romero et al. 2007]. Briefly hyperpolarizing the
spermatozoa plasma membrane from À60 mV to
À80 mV activates a calcium-dependent K + current DISCUSSION
(Fig. 3C, insert). The tail-current derived from this A previous study has indicated that the venom
response in the presence of either venom, high K + , induced cellular effect is mediated by low molecular
or TEA is plotted in Figure 3C. In most cases at weight heat sensitive peptides present in the venom,
7.5 mg/ml venom with 30 mM potassium or 50 to [Parodi and Romero 2008]. As described above,
100 mM TEA the K + currents were blocked. As the venom of the Chilean L. mactans is effective
Effect of Venom on Mature Spermatozoa Currents 39
4. Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
For personal use only.
FIGURE 2 A TEA-sensitive outwardly rectifying K + . (A), sample records of membrane currents obtained in the absence or the presence
of 5 mM TEA. (B), I/V relation from the sample currents (n ¼ 6). (C), I/V plot in increasing concentrations of K + .
TABLE 1 Calculated [I/pA ¼ f (Vm/mV)] and Experimental venom of L. mactans increases the free intracellular
Reversal Membrane Potentials. Ca ++ negatively impacting the TEA-sensitive K +
[K + ] Predicted I/V (mV) Experimental I/V (mV) spermatozoa current. All conductances are crucial to
spermatozoa capacitation.
30 mM À40 mV À43 7 7 mV
80 mM À14 mV À16 7 4 mV After several min of exposure of the spermatozoa to
140 mM 0 mV 57 2 mV the venom, free intracellular Ca ++ rises. As shown in
Figures 3A and B, the change in the membrane con-
ductance after exposure to venom suggests depolari-
even in the absence of a-latrotoxin, which is the zation and calcium channel voltage dependent
primary component described for this venom in (CCVD) activation in the spermatozoa cells. This
another species of spider [Ushkaryov et al. 2008]. may reflect the blockage of voltage-dependent K +
The results reported in this study suggest that the channels leading to the entrance of Ca ++ from the
40 J. Parodi et al.
5. Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
FIGURE 3 Venom blocks the TEA-sensitive current. (A), I/V relation in the absence or presence of 7.5 mg/ml venom. (B), the membrane
conductance is reduced in spermatozoa exposed to the venom. (C), comparative effect of venom, high K + , and increasing concentra-
tions of TEA (10 to 50 mM) on the prepulse current. The insert shows sample recordings of the prepulse in control cells and cells
exposed to venom. The bars represent means7SD of six different experiments.n
extracellular medium in accord with previous studies observed. Nevertheless the functional data reported
that suggested that the venom inhibits several K + here and elsewhere [Darszon et al. 2006; Marconi
conductances [Parodi and Romero 2008; Parodi et al. et al. 2008; Navarro et al. 2008] is consistent with
2008]. Like the oocyte Kv1.1 s [Parodi et al. 2008], this the view that Kv channels are integral to the
For personal use only.
channel is also present in the spermatozoa midpiece spermatozoa.
[Darszon et al. 1999]. Since Kv1.1 is integral to Other natural sources of spermicidal action have
membrane potential regulation [Gutman et al. 2003] been reported, including scorpion toxins and plant
we compared the effect with high K + added in the extracts [Harat et al. 2008; Lopez-Gonzalez et al.
medium. In both cases the concentration of free Ca ++ 2003]. Together with the previous studies of the
exhibited a transient rise and sharp fall as detected spermicidal properties of the venom of the Chilean
by spermatozoal midpiece fluorescence. However, L. mactans we were enabled, with a new set of
a rise in Ca ++ was observed throughout the cell pharmacological tools, to identify the active
after long periods of time. This is consistent with the compound(s) that mediate the modulation of ionic-
view that a CCVD was present [Darszon et al. 2005]. conductances. Perhaps they could provide a
A direct pharmacological study is required to specify resource for a new generation of contraceptives.
the Ca ++ and K + currents involved.
The molecular identity of the K + channel
modulated by the venom was indirectly assessed
by the activation kinetics and TEA-sensitivity of the MATERIALS AND METHODS
currents. At 5 mM TEA-blocks the outward-rectifying
K + current and likely represents a Kv1-like current
Spider Retrieval
[Marconi et al. 2008], although mouse brain large- Female adult L. mactans were captured in Chile
conductance (mSlo) has also been identified in during the summer months (December 2006 and
spermatozoa [Navarro et al. 2008]. The currents January 2007) from the area of ‘‘Alto Bio Bio’’ in the
blocked by the spider venom appear similar to those Bio-Bio state (721160 5100 W, 71450 2400 S) as previously
found in frog oocytes and neurons in culture [Parodi described [Romero et al. 2003]. Care was taken not to
and Romero 2008; Parodi et al. 2008] although damage the breeding zones. The specimens were
differences in the expression profiles of Kv channels separately maintained in individual jars. To stimulate
[Darszon et al. 2006] among species have been the production and concentration of venom in the
Effect of Venom on Mature Spermatozoa Currents 41
6. glands, the spiders were raised without food and and Marty 1988] at room temperature, using a patch-
only given water for 30 days. clamp amplifier (Warner PC-501A). For whole-cell
recordings, the external solution contained 150 mM
NaCl, 5.4 mM KCl, 2.0 mM CaCl2, 1.0 mM MgCl2,
Venom Retrieval 10 mM glucose buffered with 10 mM HEPES, pH 7.4
The spiders were immersed in liquid nitrogen and buffer. The internal solution contained 120 mM KCl,
after 1 min transferred to a phosphate saline buffer 2.0 mM MgCl2, 2 mM ATP-Na2-ATP, 10 mM BAPTA,
solution (PBS: 0.1 M NaH2PO4, 0.01 M Na2HPO4, 0.5 mM GTP buffered with 10 mM HEPES, pH 7.4
1.35 M NaCl, pH 7.4) at 41C. The glands were buffer. For perforated patch-clamp 10 mg/ml nystatine
removed and the membrane that binds them to the was added [Ermishkin et al. 1976]. For some experi-
base was sectioned. Each gland, was placed into ments, the external solution included either 7.5 g/ml
a tube containing PBS (25 pairs of glands for 100 ml of venom or 5–100 mM TEA. Spermatozoa were
of PBS) and homogenized. The homogenate was clamped at a holding potential of À60 mV. The ionic
immediately centrifuged at 1,000 Â g for 15 min. The currents were captured online and digitized at a
supernatant was subsequently aliquoted, and frozen sampling rate of 1.2 kHz using pClamp 9 (Molecular
Syst Biol Reprod Med Downloaded from informahealthcare.com by University Autonoma Barcelona
at À 201C. The protein content of the venom was Devices, Axon) after being filtered (internal 4 Bessel;
determined by a modification of the Bradford frequency cutoff ¼ 3 kHz). Pulse protocols, data
method (BioRad Protein Assay). capture, and recording analysis were performed using
pClampfit 9.0 software (Molecular Devices, Axon).
Spermatozoa
Bovine spermatozoa were obtained from samples
Fluo-3 AM Loading
cryopreserved in liquid nitrogen, which were Bovine spermatozoa were loaded with 5 mM Fluo-3
thawed at 351C for 1 min then suspended in human AM in pluronic acid/DMSO, 10% w/v (Molecular
For personal use only.
tubal fluid (HTF) medium supplemented with 3% Probes, Eugene, OR, USA) and mounted in a fast-
BSA. Spermatozoa were selected by the swim-up switching flow perfusion chamber adapted on the
technique (recommendation of [World Health stage of an inverted fluorescent microscope (Eclipse
Organization 1999]) and motile spermatozoa were TE, Nikon) equipped with a xenon lamp and a 40 Â
placed in a recording chamber coated with poly-L- objective (22–241C). The cells were briefly illumi-
lysine (0.2 mg/mL). The recording chamber was then nated (200 ms) for fast record real time analysis, using
washed with a standard external solution that a computer-controlled Lambda 10-2 filter wheel
contained 150 mM NaCl, 5.4 mM KCl, 2.0 mM CaCl2, (Sutter Instruments). Regions of interest (ROI) were
1.0 mM MgCl2, 10 mM glucose buffered with 10 mM simultaneously selected on midpiece containing
HEPES, pH 7.4 buffer. Fluo-3 fluorescence (excitation 480 nm, emission
510 nm). Images were collected at 2–5 s intervals
during a continuous 5-min period or at 0 or 30 min.
Micropipette Preparation The imaging was carried out with a 12 bit cooled
Borosilicate glass capillary tubes 1.5 mm of internal SensiCam camera (PCO, Germany), using the imag-
diameter (Sutter Instrument Co., CA, USA) were ing software Axon Workbench 2.2 (Axon Instru-
placed in a vertical puller (Narishige PP 830 m ments). The spermatozoa were exposed to 7.5 g/ml
Barishige, Tokyo, Japon) and then treated with a of total venom () or 30 mM potassium () by bath
micropolisher (Narishige MF 900) to obtain a micro- perfusion, and changes in the emission of midpiece
pipette tip with electrical resistances ranging from fluorescence, measured in FAU and scored.
10 to 12 MO.
ACKNOWLEDGMENTS
Electrophysiology Fernando Romero, Raul Sanchez, and Jorge Parodi
Electrical currents were recorded by using the were supported by the Fondef-Conicyt Chile No
perforated whole-cell patch-clamp technique [Horn ´
DO5I10416. Ataulfo Martinez-Torres was supported
42 J. Parodi et al.
7. by CONACYT 55025 and UNAM-PAPIIT 204806. Jorge Labarca, P., Zapata, O., Beltran, C. and Darszon, A. (1995) Ion channels
from the mouse sperm plasma membrane in planar lipid bilayers.
Parodi has postdoctoral fellow from CTIC-UNAM Zygote 3:199–206.
and from MIDEPLAN-Chile. Patricia Navarrete has Linares-Hernandez, L., Guzman-Grenfell, A. M., Hicks-Gomez, J. J. and
CONICYT grant. We are in debt with Dr. Luis Aguayo Gonzalez-Martinez, M. T. (1998) Voltage-dependent calcium influx in
human sperm assessed by simultaneous optical detection of intracellular
for help with measurement equipment for calcium calcium and membrane potential. Biochim Biophys Acta 1372:1–12.
experiments. Lopez-Gonzalez, I., Olamendi-Portugal, T., De la Vega-Beltran, J. L.,
Van der Walt, J., Dyason, K., Possani, L. D., Felix, R. and Darszon, A.
(2003) Scorpion toxins that block T-type Ca2+ channels in
spermatogenic cells inhibit the sperm acrosome reaction. Biochem
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Effect of Venom on Mature Spermatozoa Currents 43