RESUMEN

The global population is undergoing rapid aging, making physical activity a crucial element in preventing mortality and lowering the risk of Alzheimer's disease. Age-related declines in muscle mass and cognitive abilities significantly contribute to frailty and dependency. Thus, this study focuses on a meticulous analysis of the protective effects of multidomain interventions, an emerging resource combating age-related declines. It seeks to underscore their profound impact on cognitive flexibility and sarcopenia, highlighting their pivotal role in mitigating the adverse effects of aging. To identify relevant randomized controlled trials up to November 2023, we reviewed eight online academic databases, following PERSiST guidelines, PRISMA reporting system, and PICOs criteria. Meta-analyses on selected functional outcomes utilized a random-effects model, including the Timed Up and Go Test, Sit to Stand Test, Victoria Stroop Test, and Trail Making Test. Out of 2082 scrutinized articles, 17 were included in the systematic review, and 8 in the meta-analysis. Positive effects (p = 0.05, I2 = 57%; 95% CI - 0.63 to - 0.05) were observed in cognitive flexibility for certain interventions. Similarly, interventions addressing muscle strength demonstrated improvements in the Sit to Stand Test for the exercise group compared to the control group (p = 0.02, I2 = 0%; 95% CI - 0.63 to - 0.05). These findings underscore the importance of incorporating physical activity as a primary component of public health interventions for promoting healthy aging and reducing the burden of age-related diseases. Future interventions may explore more homogeneous approaches and evaluate the impact of thrice multidomain weekly sessions.

Asunto(s)

Cognición , Envejecimiento Saludable , Sarcopenia , Anciano , Humanos , Cognición/fisiología , Ejercicio Físico/fisiología , Envejecimiento Saludable/fisiología , Fuerza Muscular/fisiología , Ensayos Clínicos Controlados Aleatorios como Asunto , Sarcopenia/prevención & control

RESUMEN

Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in four tree species, two angiosperms (Betula pendula, Populus tremula) and two conifers (Picea abies, Pinus sylvestris), across their latitudinal distribution in Europe. Growth and hydraulic efficiency varied widely within species and between populations. The variability of embolism resistance was in general weaker than that of growth and hydraulic efficiency, and very low for all species but Populus tremula. In addition, no and weak support for a safety vs. efficiency trade-off was observed for the angiosperm and conifer species, respectively. The limited variability of embolism resistance observed here for all species except Populus tremula, suggests that forest populations will unlikely be able to adapt hydraulically to drier conditions through the evolution of embolism resistance.

Asunto(s)

Sequías , Árboles/clasificación , Árboles/fisiología , Agua , Xilema/fisiología , Clima , Europa (Continente) , Bosques , Fenotipo

RESUMEN

Mediterranean vegetation emits a wide range of biogenic volatile organic compounds (BVOCs) among which isoprenoids present quantitatively the most important compound class. Here, we investigated the isoprenoid emission from two Mediterranean Cistaceae shrubs, Halimium halimifolium and Cistus ladanifer, under controlled and natural conditions, respectively. For the first time, diurnal emission patterns of the diterpene kaurene were detected in real-time by Proton-Transfer-Reaction-Time-of-Flight-Mass-Spectrometer. Kaurene emissions were strongly variable among H. halimifolium plants, ranging from 0.01 ± 0.003 to 0.06 ± 0.01 nmol m-2 s-1 in low and high emitting individuals, respectively. They were in the same order of magnitude as monoterpene (0.01 ± 0.01 to 0.11 ± 0.04 nmol m-2 s-1) and sesquiterpene (0.01 ± 0.01 to 0.52 nmol m-2 s-1) emission rates. Comparable range and variability was found for C. ladanifer under natural conditions. Labelling with 13C-pyruvate suggested that emitted kaurene was not derived from de novo biosynthesis. The high kaurene content in leaves, the weak relationship with ecophysiological parameters and the tendency of higher emissions with increasing temperatures in the field indicate an emission from storage pools. This study highlights significant emissions of kaurene from two Mediterranean shrub species, indicating that the release of diterpenes into the atmosphere should probably deserve more attention in the future.

Asunto(s)

Atmósfera/química , Cistus/metabolismo , Diterpenos de Tipo Kaurano , Hojas de la Planta/metabolismo , Compuestos Orgánicos Volátiles , Ritmo Circadiano , Diterpenos de Tipo Kaurano/análisis , Diterpenos de Tipo Kaurano/metabolismo , Ecosistema , Monoterpenos/análisis , Monoterpenos/metabolismo , Portugal , Sesquiterpenos/análisis , Sesquiterpenos/metabolismo , Temperatura , Compuestos Orgánicos Volátiles/análisis , Compuestos Orgánicos Volátiles/metabolismo

RESUMEN

Objetivo. Comparar os efeitos do programa escola de postura (PEP) e reeducação postural global (RPG) sobre níveis de dor e amplitude de movimento em pacientes com lombalgia crônica. Método. A amostra foi dividida em 3 grupos de 10 sujeitos: grupo submetido ao tratamento através do PEP (idade: 46.30 ± 8.50 anos); grupo submetido ao tratamento através da RPG (idade: 43.60 ± 10.93 anos) e grupo controle (idade: 44.30 ± 10.68 anos). As intervenções foram realizadas em 10 sessões. Para avaliação do quadro álgico foi utilizada a escala subjetiva de dor CR10 de Borg. Para a análise da amplitude de movimento empregou‐se o protocolo de goniometria LABIFIE para os movimentos de extensão coxofemoral (ECF) e flexão da coluna lombar (FCL). Resultados. O teste de Wilcoxon mostrou uma redução nos escores dos níveis de dor nos grupos PEP e RPG (p < 0.0001) do pré para o pós‐tratamento. As comparações intergrupos, através do teste de Kruskal‐Wallis, apresentaram diminuição dos níveis de dor para o PEP (p < 0.0001) e o RPG (p < 0.0001) quando comparados ao CG no pós‐tratamento. A ANOVA com medidas repetidas revelou um aumento na amplitude do movimento para o PEP (ECF: p = 0.006; FCL: p = 0.002) e RPG (ECF: p = 0.034; FCL: p = 0.011) do pré para o pós‐tratamento. As comparações intergrupos apresentaram maiores amplitudes de movimento para o PEP (ECF: p = 0.006; FCL: p = 0.018) e RPG (EQ: p = 0.019; FCL: p = 0.020) quando comparados ao CG no pós‐tratamento. Não houve diferenças significativas entre o PEP e RPG. Conclusão. Os tratamentos PEP e RPG se mostraram eficientes para redução da lombalgia crónica (AU)

---

Objetivo. Comparar los efectos de un programa de escuela de postura (PEP) y reeducación postural global (RPG) individual sobre niveles de dolor y rango de movimiento en pacientes con dolor lumbar crónico. Método. La muestra se dividió en 3 grupos de 10 sujetos: grupo tratado por PEP (edad: 46.30 ± 8.50 años), grupo tratado por RPG (edad: 43.60 ± 10.93 años) y grupo control (edad: 44.30 ± 10.68 años). Las intervenciones se llevaron a cabo en 10 sesiones. Para la evaluación del dolor se utilizó la escala subjetiva del dolor CR10 Borg. Para el análisis de rango de movimiento, se utilizó el protocolo de goniometría en los movimientos de extensión de la cadera (EC) y flexión de la columna lumbar (FCL). Resultados. La prueba de Wilcoxon mostró una reducción en los niveles de dolor en los grupos de PEP y RPG (p < 0.0001). Las comparaciones entre los grupos mediante el test de Kruskal‐Wallis mostró disminución de los niveles de dolor para el PEP (p < 0.0001) y RPG (p < 0.0001) en comparación con CG después del tratamiento. El ANOVA con medidas repetidas reveló un aumento en rango de movimiento para el PEP (EC: p = 0.006; FCL: p = 0.002) y RPG (EC: p = 0.034; FCL: p = 0.011). Las comparaciones entre los grupos mostraron un mayor rango de movimiento para el PEP (EC: p = 0.006; FCL: p = 0.018) y RPG (EC: p = 0.019; FCL: p = 0.020) en comparación con el GC después del tratamiento. No hubo diferencias significativas entre el PEP y RPG. Conclusión. Los tratamientos de PEP y RPG fueron eficaces para reducir el dolor lumbar crônico (AU)

---

Objective. To compare the effects of school‐based exercise program of posture (SPP) and global postural reeducation (GPR) on pain levels and range of motion in patients with chronic low back pain. Method. The sample was divided into three groups of 10 subjects: group treated by SPP (age: 46.30 ± 8.50 years) group subjected to treatment by GPR (age: 43.60 ± 10.93 years) and control group (age: 44.30 ± 10.68 years). The interventions were performed in 10 sessions. For assessment of pain was used pain subjective scale CR10‐Borg. For the analysis of range of motion, we used the protocol to goniometry LABIFIE in the movements of hip extension (HE) and flexion of the lumbar spine (FLS). Results. The Wilcoxon test showed a reduction in levels of pain scores in groups SPP and GPR (p < 0.0001) of pre to post‐treatment. Comparisons between groups by the Kruskal‐Wallis test showed decreased levels of pain for SPP (p < 0.0001) and GPR (p < 0.0001) when compared to CG post‐treatment. Repeated measures ANOVA revealed an increase in range of motion for the SPP (HE: p = 0.006; FLS: p = 0.002) and GPR (HE: p = 0.034; FLS: p = 0.011) of pre to post‐treatment. Comparisons between groups showed greater range of motion for the SPP (HE: p = 0.006; FLS: p = 0.018) and GPR (HE: p = 0.019; FLS: p = 0.020) when compared to CG post‐treatment. There were no significant differences between the SPP and GPR. Conclusions. SPP and GPR treatments were effective for reducing chronic low back pain (AU)

Asunto(s)

Humanos , Masculino , Femenino , Educación Primaria y Secundaria , Dolor de la Región Lumbar/complicaciones , Dolor de la Región Lumbar/patología , Artrometría Articular/instrumentación , Artrometría Articular/métodos , Prótesis de Cadera/clasificación , Estadísticas no Paramétricas , Terapéutica/métodos , Dolor de la Región Lumbar/diagnóstico , Dolor de la Región Lumbar/metabolismo , Artrometría Articular/normas , Artrometría Articular , Prótesis de Cadera/normas , Terapéutica/instrumentación , Análisis de Varianza

RESUMEN

We investigate model Mt,α  for abundance estimation in closed-population capture-recapture studies, where animals are identified from natural marks such as DNA profiles or photographs of distinctive individual features. Model Mt,α  extends the classical model Mt  to accommodate errors in identification, by specifying that each sample identification is correct with probability α and false with probability 1-α. Information about misidentification is gained from a surplus of capture histories with only one entry, which arise from false identifications. We derive an exact closed-form expression for the likelihood for model Mt,α  and show that it can be computed efficiently, in contrast to previous studies which have held the likelihood to be computationally intractable. Our fast computation enables us to conduct a thorough investigation of the statistical properties of the maximum likelihood estimates. We find that the indirect approach to error estimation places high demands on data richness, and good statistical properties in terms of precision and bias require high capture probabilities or many capture occasions. When these requirements are not met, abundance is estimated with very low precision and negative bias, and at the extreme better properties can be obtained by the naive approach of ignoring misidentification error. We recommend that model Mt,α  be used with caution and other strategies for handling misidentification error be considered. We illustrate our study with genetic and photographic surveys of the New Zealand population of southern right whale (Eubalaena australis).

Asunto(s)

Artefactos , Funciones de Verosimilitud , Modelos Estadísticos , Reconocimiento de Normas Patrones Automatizadas/métodos , Vigilancia de la Población/métodos , Ballenas , Algoritmos , Animales , Simulación por Computador , Interpretación Estadística de Datos , Nueva Zelanda/epidemiología , Densidad de Población , Dinámica Poblacional , Tamaño de la Muestra

RESUMEN

Monitoring results are presented as an annual water balance from the pioneering Landcare Research green building containing commercial laboratory and office space. The building makes use of harvested roof runoff to flush toilets and urinals and irrigate glasshouse experiments, reducing the demand for city-supplied water and stormwater runoff. Stormwater treatment devices also manage the runoff from the carpark, helping curb stream degradation. Composting toilets and low-flow tap fittings further reduce the water demand. Despite research activities requiring the use of large volumes of water, the demand for city-supplied water is less than has been measured in many other green buildings. In line with the principles of sustainability, the composting toilets produce a useable product from wastes and internalise the wastewater treatment process.

Asunto(s)

Conservación de los Recursos Naturales/métodos , Drenaje de Agua , Reciclaje/métodos , Urbanización , Eliminación de Residuos Líquidos/métodos , Conservación de los Recursos Naturales/economía , Arquitectura y Construcción de Instituciones de Salud , Lluvia , Reciclaje/economía , Abastecimiento de Agua

RESUMEN

*The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. *Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. *Total ecosystem respiration (R(eco)) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (R(auto))), were elevated on the TFE plot relative to the control. The increase in PCE and R(eco) was mainly caused by a rise in R(auto) from foliage and roots. Heterotrophic respiration did not differ substantially between plots. NPP was 2.4 +/- 1.4 t C ha(-1) yr(-1) lower on the TFE than the control. Ecosystem carbon use efficiency, the proportion of PCE invested in NPP, was lower in the TFE plot (0.24 +/- 0.04) than in the control (0.32 +/- 0.04). *Drought caused by the TFE treatment appeared to drive fundamental shifts in ecosystem C cycling with potentially important consequences for long-term forest C storage.

Asunto(s)

Carbono/metabolismo , Sequías , Árboles/metabolismo , Bacterias/metabolismo , Brasil , Dióxido de Carbono/metabolismo , Respiración de la Célula , Ecosistema , Suelo , Factores de Tiempo

RESUMEN

Integrated Urban Water Management (IUWM) acknowledges a broad range of environmental and socio-economic outcomes but the link between design intentions and operational performance is not always clear. This may be due in part to a lack of shared principles that remove bias and inconsistency in assessing the operational performance of IUWM. This paper investigates the possibility of developing shared principles through examination of shared objectives and shared indicators within two logical and integrated frameworks for urban residential developments that aspire for IUWM and sustainable development. The framework method was applied using very different approaches-one a top-down urban planning process, the other a bottom-up community consultation process. Both frameworks highlight the extent to which IUWM is part of a broad social and environmental system. Core environmental performance objectives and indicators were very similar, highlighting the potential to develop shared principles in reporting and benchmarking the environmental performance of neighbourhood developments. Socio-economic indicators were highly variable due to process and likely contextual differences, thus it is unclear if the influence of IUWM on these variables can transcend the social context unless the practice of urban water management can expand its core responsibility beyond "hard" physical infrastructure.

Asunto(s)

Planificación de Ciudades/métodos , Eliminación de Residuos Líquidos/métodos , Abastecimiento de Agua/normas , Conservación de los Recursos Naturales/métodos , Crimen/prevención & control , Estudios de Factibilidad , Salud , Humanos , Nueva Zelanda , Dinámica Poblacional , Seguridad , Factores Socioeconómicos

RESUMEN

Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were monitored during the progressive summer drought to establish how changes along the hydraulic pathway influence shoot responses. As soil water became limiting, leaf water potential, stomatal conductance and leaf transpiration declined significantly. Predawn leaf water potential reflected soil water potential measured at 1-m depth in the rhizospheres of most trees. The lowest predawn leaf water potential recorded during this period was -1.8 MPa. Mean maximum stomatal conductance declined from 300 to 50 mmol m(-2) s(-1), reducing transpiration from 6 to 2 mmol m(-2) s(-1). Changes in leaf gas exchange were attributed to reduced soil water availability, increased resistances along the hydraulic pathway and, hence, reduced leaf water supply. There was a strong coupling between changes in soil water content and stomatal conductance as well as between stomatal conductance and leaf specific hydraulic conductance. Despite significant seasonal differences among trees in predawn leaf water potential, stomatal conductance, leaf transpiration and leaf specific hydraulic conductance, there were no differences in midday leaf water potentials. The strong regulation of changes in leaf water potential in Q. suber both diurnally and seasonally is achieved through stomatal closure, which is sensitive to changes in both liquid and vapor phase conductance. This sensitivity allows for optimization of carbon and water resource use without compromising the root-shoot hydraulic link.

Asunto(s)

Ecosistema , Transpiración de Plantas/fisiología , Quercus/fisiología , Suelo/análisis , Agua/metabolismo , Carbono/metabolismo , Ritmo Circadiano/fisiología , Hojas de la Planta/metabolismo , Portugal , Quercus/metabolismo , Estaciones del Año , Agua/análisis , Tiempo (Meteorología)

RESUMEN

Cytoplasmic mRNA localization provides a means of generating cell asymmetry and segregating protein activity. Previous studies have identified two mRNAs that localize to the bud tips of the yeast Saccharomyces cerevisiae. To identify additional localized mRNAs, we immunoprecipitated the RNA transport components She2p, She3p, and Myo4p and performed DNA microarray analysis of their associated RNAs. A secondary screen, using a GFP-tagged RNA reporter assay, identified 22 mRNAs that are localized to bud tips. These messages encode a wide variety of proteins, including several involved in stress responses and cell wall maintenance. Many of these proteins are asymmetrically localized to buds. However, asymmetric localization also occurs in the absence of RNA transport, suggesting the existence of redundant protein localization mechanisms. In contrast to findings in metazoans, the untranslated regions are dispensable for mRNA localization in yeast. This study reveals an unanticipated widespread use of RNA transport in budding yeast.

Asunto(s)

Citoplasma/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/metabolismo , Transporte Biológico , Pruebas de Precipitina

RESUMEN

Kinesin motors move on microtubules by a mechanism that involves a large, ATP-triggered conformational change in which a mechanical element called the neck linker docks onto the catalytic core, making contacts with the core throughout its length. Here, we investigate the thermodynamic properties of this conformational change using electron paramagnetic resonance (EPR) spectroscopy. We placed spin probes at several locations on the human kinesin neck linker and recorded EPR spectra in the presence of microtubules and either 5'-adenylylimidodiphosphate (AMPPNP) or ADP at temperatures of 4-30 degrees C. The free-energy change (DeltaG) associated with AMPPNP-induced docking of the neck linker onto the catalytic core is favorable but small, about 3 kJ/mol. In contrast, the favorable enthalpy change (DeltaH) and unfavorable entropy change (TDeltaS) are quite large, about 50 kJ/mol. A mutation in the neck linker, V331A/N332A, results in an unfavorable DeltaG for AMPPNP-induced zipping of the neck linker onto the core and causes motility defects. These results suggest that the kinesin neck linker folds onto the core from a more unstructured state, thereby paying a large entropic cost and gaining a large amount of enthalpy.

Asunto(s)

Dominio Catalítico , Espectroscopía de Resonancia por Spin del Electrón/métodos , Cinesinas/química , Microtúbulos/química , Proteínas Motoras Moleculares/química , Movimiento (Física) , Sitios de Unión , Transferencia de Energía , Humanos , Cinesinas/genética , Mutación , Unión Proteica , Conformación Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Marcadores de Spin/síntesis química , Estrés Mecánico , Temperatura

Asunto(s)

Membrana Celular/metabolismo , Membranas Intracelulares/metabolismo , Proteínas Motoras Moleculares/metabolismo , Transporte de Proteínas , Receptores Citoplasmáticos y Nucleares/metabolismo , Subunidades alfa de Complejo de Proteína Adaptadora , Proteínas Adaptadoras del Transporte Vesicular , Proteínas Portadoras , Citoesqueleto/metabolismo , Dineínas/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de Unión al GTP Monoméricas/metabolismo , Espectrina/metabolismo

RESUMEN

Vg1, a member of the transforming growth factor-beta family involved in mesoderm induction, is translated subsequent to the localization of its mRNA to the vegetal pole of Xenopus oocytes. Whereas the localization of Vg1 mRNA is known to be directed by the 3' untranslated region (UTR), the basis of its translational regulation is unknown. We show here that the 3' UTR of Vg1 causes translational repression of two different reporter mRNAs in Xenopus oocytes. A 350-nucleotide region of the 3' UTR, which is distinct from the localization element, is necessary and sufficient for mediating translational repression and specifically binds to a 38-kDa polypeptide. The translational repression activity is found throughout the oocyte and at all stages of oogenesis. These results suggest that factors colocalized with Vg1 mRNA at the vegetal pole relieve translational repression to allow expression of Vg1 protein.

Asunto(s)

Regulación de la Expresión Génica/fisiología , Glicoproteínas/genética , Oocitos/fisiología , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Regiones no Traducidas 3'/genética , Animales , Polaridad Celular , Femenino , Oocitos/citología , ARN Mensajero/análisis , Transcripción Genética , Factor de Crecimiento Transformador beta/genética , Proteínas de Xenopus , Xenopus laevis

RESUMEN

Conventional kinesin, a dimeric molecular motor, uses ATP-dependent conformational changes to move unidirectionally along a row of tubulin subunits on a microtubule. Two models have been advanced for the major structural change underlying kinesin motility: the first involves an unzippering/zippering of a small peptide (neck linker) from the motor catalytic core and the second proposes an unwinding/rewinding of the adjacent coiled-coil (neck coiled-coil). Here, we have tested these models using disulfide cross-linking of cysteines engineered into recombinant kinesin motors. When the neck linker motion was prevented by cross-linking, kinesin ceased unidirectional movement and only showed brief one-dimensional diffusion along microtubules. Motility fully recovered upon adding reducing agents to reverse the cross-link. When the neck linker motion was partially restrained, single kinesin motors showed biased diffusion towards the microtubule plus end but could not move effectively against a load imposed by an optical trap. Thus, partial movement of the neck linker suffices for directionality but not for normal processivity or force generation. In contrast, preventing neck coiled-coil unwinding by disulfide cross-linking had relatively little effect on motor activity, although the average run length of single kinesin molecules decreased by 30-50%. These studies indicate that conformational changes in the neck linker, not in the neck coiled-coil, drive processive movement by the kinesin motor.

Asunto(s)

Disulfuros/metabolismo , Cinesinas/química , Cinesinas/metabolismo , Proteínas Motoras Moleculares/química , Proteínas Motoras Moleculares/metabolismo , Reactivos de Enlaces Cruzados/química , Reactivos de Enlaces Cruzados/metabolismo , Difusión , Dimerización , Humanos , Cinesinas/genética , Microtúbulos/metabolismo , Proteínas Motoras Moleculares/genética , Mutagénesis/fisiología , Estructura Secundaria de Proteína/fisiología

RESUMEN

Conventional kinesin is a highly processive molecular motor that takes several hundred steps per encounter with a microtubule. Processive motility is believed to result from the coordinated, hand-over-hand motion of the two heads of the kinesin dimer, but the specific factors that determine kinesin's run length (distance traveled per microtubule encounter) are not known. Here, we show that the neck coiled-coil, a structure adjacent to the motor domain, plays an important role in governing the run length. By adding positive charge to the neck coiled-coil, we have created ultra-processive kinesin mutants that have fourfold longer run lengths than the wild-type motor, but that have normal ATPase activity and motor velocity. Conversely, adding negative charge on the neck coiled-coil decreases the run length. The gain in processivity can be suppressed by either proteolytic cleavage of tubulin's negatively charged COOH terminus or by high salt concentrations. Therefore, modulation of processivity by the neck coiled-coil appears to involve an electrostatic tethering interaction with the COOH terminus of tubulin. The ability to readily increase kinesin processivity by mutation, taken together with the strong sequence conservation of the neck coiled-coil, suggests that evolutionary pressures may limit kinesin's run length to optimize its in vivo function.

Asunto(s)

Cinesinas/química , Cinesinas/genética , Proteínas Motoras Moleculares/química , Proteínas Motoras Moleculares/genética , Secuencia de Aminoácidos , Electroquímica , Cinesinas/metabolismo , Proteínas Motoras Moleculares/metabolismo , Datos de Secuencia Molecular , Mutagénesis/fisiología , Mutación Puntual/fisiología , Ingeniería de Proteínas , Estructura Cuaternaria de Proteína , Estructura Secundaria de Proteína/fisiología , Sales (Química) , Tubulina (Proteína)/metabolismo

RESUMEN

Using squid axoplasm as a model system, we have visualized the fast transport of non-filamentous neurofilament protein particles along axonal microtubules. This transport occurs at speeds of 0.5-1.0 microm/second and the majority of neurofilament particles stain with kinesin antibody. These observations demonstrate, for the first time, that fast (0.5-1.0 microm/second) transport of neurofilament proteins occurs along microtubules. In addition, our studies suggest that neurofilament protein can be transported as non-membrane bound, nonfilamentous subunits along axons, and that the transport is kinesin-dependent. Microtubule-based fast transport might therefore provide a mechanism for the distribution and turnover of neurofilament, and perhaps other cytoskeletal proteins, throughout neurons.

Asunto(s)

Axones/fisiología , Microtúbulos/fisiología , Proteínas de Neurofilamentos/metabolismo , Secuencia de Aminoácidos , Animales , Transporte Axonal , Decapodiformes , Epítopos/química , Técnica del Anticuerpo Fluorescente , Cinesinas/análisis , Cinesinas/química , Cinesinas/metabolismo , Cinética , Datos de Secuencia Molecular , Subunidades de Proteína , Transporte de Proteínas , Factores de Tiempo

RESUMEN

Asymmetric localization of proteins plays a key role in many cellular processes, including cell polarity and cell fate determination. Using DNA microarray analysis, we identified a plasma membrane protein-encoding mRNA (IST2) that is transported to the bud tip by an actomyosin-based process. mRNA localization created a higher concentration of IST2 protein in the bud compared with that of the mother cell, and this asymmetry was maintained by a septin-mediated membrane diffusion barrier at the mother-bud neck. These results indicate that yeast creates distinct plasma membrane compartments, as has been described in neurons and epithelial cells.

Asunto(s)

Proteínas de Ciclo Celular/metabolismo , Proteínas del Citoesqueleto , Proteínas de Unión al ADN , Proteínas Fúngicas/metabolismo , Proteínas de la Membrana/metabolismo , Cadenas Pesadas de Miosina , Miosina Tipo V , ARN Mensajero/metabolismo , Proteínas Represoras , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Actomiosina/metabolismo , Transporte Biológico , Compartimento Celular , Ciclo Celular , Proteínas de Ciclo Celular/genética , Membrana Celular/metabolismo , Difusión , Proteínas Fúngicas/genética , Proteínas de la Membrana/genética , Mutación , Miosinas/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN de Hongos/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Temperatura , Factores de Transcripción/genética

RESUMEN

The chemotaxis signal protein CheY of enteric bacteria shuttles between transmembrane methyl-accepting chemotaxis protein (MCP) receptor complexes and flagellar basal bodies [1]. The basal body C-rings, composed of the FliM, FliG and FliN proteins, form the rotor of the flagellar motor [2]. Phosphorylated CheY binds to isolated FliM [3] and may also interact with FliG [4], but its binding to basal bodies has not been measured. Using the chemorepellent acetate to phosphorylate and acetylate CheY [5], we have measured the covalent-modification-dependent binding of a green fluorescent protein-CheY fusion (GFP-CheY) to motor assemblies in bacteria lacking MCP complexes by evanescent wave microscopy [6]. At acetate concentrations that cause solely clockwise rotation, GFP-CheY molecules bound to native basal bodies or to overproduced rotor complexes with a stoichiometry comparable to the number of C-ring subunits. GFP-CheY did not bind to rotors lacking FIiM/FliN, showing that these subunits are essential for the association. This assay provides a new means of monitoring protein-protein interactions in signal transduction pathways in living cells.

Asunto(s)

Proteínas Bacterianas/metabolismo , Quimiotaxis , Escherichia coli/metabolismo , Flagelos/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Escherichia coli/química , Escherichia coli/ultraestructura , Proteínas de Escherichia coli , Flagelos/química , Flagelos/ultraestructura , Proteínas Fluorescentes Verdes , Immunoblotting , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Proteínas Quimiotácticas Aceptoras de Metilo , Microscopía Fluorescente , Unión Proteica , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo

Asunto(s)

Adenosina Trifosfatasas/clasificación , Adenosina Trifosfatasas/metabolismo , Proteínas/metabolismo , Unión Competitiva/fisiología , Biopolímeros/metabolismo , Modelos Moleculares , Proteínas Motoras Moleculares/metabolismo , Unión Proteica/fisiología , Conformación Proteica , Pliegue de Proteína , Estructura Terciaria de Proteína/fisiología , Proteínas/química

RESUMEN

Kinesin, a microtubule-based motor, and myosin, an actin-based motor, share a similar core structure, indicating that they arose from a common ancestor. However, kinesin lacks the long lever-arm domain that is believed to drive the myosin power stroke. Here, we present evidence that a much smaller region of ca. 10-40 amino acids serves as a mechanical element for kinesin motor proteins. These 'neck regions' are class conserved and have distinct structures in plus-end and minus-end-directed kinesin motors. Mutagenesis studies also indicate that the neck regions are involved in coupling ATP hydrolysis and energy into directional motion along the microtubule. We suggest that the kinesin necks drive motion by undergoing a conformational change in which they detach and re-dock onto the catalytic core during the ATPase cycle. Thus, kinesin and myosin have evolved unique mechanical elements that amplify small, nucleotide-dependent conformational changes that occur in their similar catalytic cores.

Asunto(s)

Cinesinas/química , Cinesinas/fisiología , Proteínas Motoras Moleculares/fisiología , Movimiento/fisiología , Animales , Modelos Moleculares , Proteínas Motoras Moleculares/química , Contracción Muscular , Miosinas/química , Miosinas/fisiología , Conformación Proteica