Properties of the Inner Pore Region of TRPV1 Channels Revealed by Block with Quaternary Ammoniums

The transient receptor potential vanilloid 1 (TRPV1) nonselective cationic channel is a polymodal receptor that activates in response to a wide variety of stimuli. To date, little structural information about this channel is available. Here, we used quaternary ammonium ions (QAs) of different sizes in an effort to gain some insight into the nature and dimensions of the pore of TRPV1. We found that all four QAs used, tetraethylammonium (TEA), tetrapropylammonium (TPrA), tetrabutylammonium, and tetrapentylammonium, block the TRPV1 channel from the intracellular face of the channel in a voltage-dependent manner, and that block by these molecules occurs with different kinetics, with the bigger molecules becoming slower blockers. We also found that TPrA and the larger QAs can only block the channel in the open state, and that they interfere with the channel's activation gate upon closing, which is observed as a slowing of tail current kinetics. TEA does not interfere with the activation gate, indicating that this molecule can reside in its blocking site even when the channel is closed. The dependence of the rate constants on the size of the blocker suggests a size of around 10 Å for the inner pore of TRPV1 channels

Dequalinium: A Novel, High-affinity Blocker of CNGA1 Channels

Cyclic nucleotide–gated (CNG) channels have been shown to be blocked by diltiazem, tetracaine, polyamines, toxins, divalent cations, and other compounds. Dequalinium is an organic divalent cation which suppresses the rat small conductance Ca2+-activated K+ channel 2 (rSK2) and the activity of protein kinase C. In this study, we have tested the ability of dequalinium to block CNGA1 channels and heteromeric CNGA1+CNGB1 channels. When applied to the intracellular side of inside-out excised patches from Xenopus oocytes, dequalinium blocks CNGA1 channels with a K1/2 ≈ 190 nM and CNGA1+CNGB1 channels with a K1/2 ≈ 385 nM, at 0 mV. This block occurs in a state-independent fashion, and is voltage dependent with a zδ ≈ 1. Our data also demonstrate that dequalinium interacts with the permeant ion probably because it occupies a binding site in the ion conducting pathway. Dequalinium applied to the extracellular surface also produced block, but with a voltage dependence that suggests it crosses the membrane to block from the inside. We also show that at the single-channel level, dequalinium is a slow blocker that does not change the unitary conductance of CNGA1 channels. Thus, dequalinium should be a useful tool for studying permeation and gating properties of CNG channels

State-dependent Block of CNG Channels by Dequalinium

Cyclic nucleotide–gated (CNG) ion channels are nonselective cation channels with a high permeability for Ca(2+). Not surprisingly, they are blocked by a number of Ca(2+) channel blockers including tetracaine, pimozide, and diltiazem. We studied the effects of dequalinium, an extracellular blocker of the small conductance Ca(2+)-activated K(+) channel. We previously noted that dequalinium is a high-affinity blocker of CNGA1 channels from the intracellular side, with little or no state dependence at 0 mV. Here we examined block by dequalinium at a broad range of voltages in both CNGA1 and CNGA2 channels. We found that dequalinium block was mildly state dependent for both channels, with the affinity for closed channels 3–5 times higher than that for open channels. Mutations in the S4-S5 linker did not alter the affinity of open channels for dequalinium, but increased the affinity of closed channels by 10–20-fold. The state-specific effect of these mutations raises the question of whether/how the S4-S5 linker alters the binding of a blocker within the ion permeation pathway

Morphology and Sequence Data of Mexican Populations of the Ciliate Parasite of Marine Fishes Trichodina rectuncinata (Ciliophora: Trichodinidae)

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric- molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.Fil: Islas Ortega, Alma G.. Universidad Nacional Autónoma de México; MéxicoFil: Aguilar Aguilar, Rogelio. Universidad Nacional Autónoma de México; MéxicoFil: Marcotegui, Paula Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Hernández Mena, David. Universidad Nacional Autónoma de México; MéxicoFil: Pérez Ponce de León, Gerardo. Universidad Nacional Autónoma de México; Méxic

Morphology and Sequence Data of Mexican Populations of the Ciliate Parasite of Marine Fishes Trichodina rectuncinata (Ciliophora: Trichodinidae)

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric- molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.Centro de Estudios Parasitológicos y de Vectore

Morphology and Sequence Data of Mexican Populations of the Ciliate Parasite of Marine Fishes Trichodina rectuncinata (Ciliophora: Trichodinidae)

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric- molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.Centro de Estudios Parasitológicos y de Vectore

Recursos audiovisuales en la educación en enfermería: revisión de la literatura

Introduction: Audiovisual aids, as a teaching strategy, promote a change from the traditional educational system to an improved way of learning that integrates technological advances and resources to enhance education, this is why it is important to gather all the existent information about the topic, because we need to demonstrate and support its’ usage for the students development. Aim:Analyze the existent information about the impact that audiovisual aids have in the improvement or nursing teaching.Methodology: Systematic research in the Medina, CINAHL, EBSCO, SciELO, PubMed, LILACS and Cochrane databases. Using de PICo method and Health Science Descriptors (DeCS) in English, Spanish and Portuguese. Results: Seven experimental and quasi-experimental studies were selected, which showed that audiovisual aids helped in the improvement of declarative, contextual and attitudinal learning, nevertheless, they did not surpass the situated strategies such as simulations, authorized practices and interactive activities. Conclusion: The evidence showed that the use of audiovisual aids developed empathy and helped the students’ inner expression, however they are not able to outstep the constructive learning strategies by themselves.Introducción. Los recursos audiovisuales como estrategias de enseñanza fomentan el cambio de una educación tradicional hacia una que integra los cambios tecnológicos, la cual utiliza y dispone de los recursos para mejorar el aprendizaje, por lo que es necesario contar con la mejor evidencia disponible para apoyar su utilización en la formación de los estudiantes.Objetivo. Analizar la evidencia existente del impacto que tienen los recursos audiovisuales en el mejoramiento de la enseñanza en enfermería.Metodología. Búsqueda sistematizada en las bases de datos Medline, CINAHL, EBSCO, SciELO, ERIC, PubMed, LILACS y Cochrane. Utilizando el método PICo y Descriptores de Ciencias de la Salud (DeSC) en inglés, español y portugués.Resultados. Se seleccionaron 7 estudios experimentales y cuasi-experimentales dónde se observa que los recursos audiovisuales ayudan a mejorar el aprendizaje declarativo, contextual y actitudinal, sin embargo, no superan a las estrategias situadas como la simulación, práctica tutorizada y actividades interactivas.Conclusiones. La evidencia demuestra que el uso de los recursos audiovisuales desarrolla la empatía y favorece la expresión de la interioridad del alumno, sin embargo, por sí solos no superan a estrategias de aprendizaje constructivistas.

The European Eel NCCβ Gene Encodes a Thiazide-Resistant Na-Cl Cotransporter

The thiazide-sensitive Na-Cl cotransporter (NCC) is the major pathway for salt reabsorption in the mammalian distal convoluted tubule. NCC plays a key role in the regulation of blood pressure. Its inhibition with thiazides constitutes the primary baseline therapy for arterial hypertension. However, the thiazide-binding site in NCC is unknown. Mammals have only one gene encoding for NCC. The eel, however, contains a duplicate gene. NCCα is an ortholog of mammalian NCC and is expressed in the kidney. NCCβ is present in the apical membrane of the rectum. Here we cloned and functionally characterized NCCβ from the European eel. The cRNA encodes a 1043-amino acid membrane protein that, when expressed in Xenopus oocytes, functions as an Na-Cl cotransporter with two major characteristics, making it different from other known NCCs. First, eel NCCβ is resistant to thiazides. Single-point mutagenesis supports that the absence of thiazide inhibition is, at least in part, due to the substitution of a conserved serine for a cysteine at position 379. Second, NCCβ is not activated by low-chloride hypotonic stress, although the unique Ste20-related proline alanine-rich kinase (SPAK) binding site in the amino-terminal domain is conserved. Thus, NCCβ exhibits significant functional differences from NCCs that could be helpful in defining several aspects of the structure-function relationship of this important cotransporter

Effect of bunches shading on color and antioxidant capacity of red table grapes (Vitis vinifera L.)

[SPA] El color es el principal atributo externo de calidad en las uvas rojas (Vitis vinifera L.). Es conferido por las antocianinas, compuestos fenólicos que además presentan actividad antioxidante. Ambas propiedades son influenciadas por la luminosidad y temperatura que alcanzan los racimos, sin embargo, los mecanismos involucrados aún no se conocen. El objetivo de este trabajo fue estudiar el efecto del sombreado sobre la capacidad antioxidante y la actividad de peroxidasas en relación con el color de bayas de uvas ´Flame Seedless´. Durante las temporadas 2003–2004 y 2004-2005, se sombrearon racimos desde el pre-envero a cosecha. Un tratamiento fue cubierto con una red blanca, otro con una red negra, ambas retenían el 50% de la luminosidad; el último con una red negra que retenía el 35% y un testigo sin red. Se encontraron efectos significativos de los tratamientos y una marcada influencia de la estación de crecimiento. El sombreado con la red blanca alcanzó menos color en ambos años: CIRG= 2.68 y 2.60 con 744.1±7.9 y 763.3±32.9 μg g-1 de antocianinas respectivamente. Los tratamientos sombreados con las redes negra obtuvieron valores superiores a tres en ambos años, explicado por contenidos de pigmentos que oscilaron entre 779.3±36.3 y 1034.5± 8.3 μg g-1 (r= 0.83). En cuanto a fenoles totales, el testigo obtuvo valores significativamente superiores a los otros tratamientos. La capacidad antioxidante se relacionó con el color (r=-0.62), sin embargo, la actividad de peroxidasas no se relacionó. De acuerdo a la selección de variables, el color fue explicado por la temperatura mínima que alcanzó el racimo (R2=0.89). Esta variable y la intensidad lumínica explicaron la capacidad antioxidante (R2=0.72). En conclusión, el sombreado de racimos con la red negra que retuvo el 35% de luminosidad resultó mejor y podría recomendarse como práctica, si bien son necesarios más estudios bioquímicos y moleculares. [ENG] conferred by anthocyanins, phenolic compounds which present antioxidant activity too. Luminosity and temperature are environmental factors that affect both properties; however mechanisms involved are unknown yet. In consequence, the objective of this work was to study the effect of shading on antioxidant capacity and peroxidase activity in relationship to berries color of ´Flame Seedless´ grapes. During 2003-2004 and 2004-2005 growing seasons, bunches were shaded from pre-veraisson to maturity. One treatment was covered with a White net, other with a black net wich both retained 50% of luminosity; the last was covered with a black net that retained only 35% of luminosity, and a control without net. Significative treatment effects and an enhanced growing season influence were found. Bunches covered with white net got minus color in both growing seasons: CIRG= 2.68 and 2.60 and anthocyanins = 744.1±7.9 and 763.3±32.9 μg g-1 respectively, while covered with black nets got higher values (CIRG>3), explained by pigments contents which oscillated between 779.3±36.3 and 1034.5± 8.3 μg g-1 (r= 0.83). Antioxidant capacity was negatively correlated with color (r=-0.62) however peroxidases activity was not correlation. According to variables selction, color was explained by minimum temperature that bunches get (R2=0.89), meanwhile, antioxidant capacity was explained by the last variable and maximum luminosity (R2=0.72). In conclusion, the black net that retained 35% of luminosity was the best and could be recommended as an agronomic practice to improve color; however more biochemical and molecular studies that explain coloration mechanisms are necessary