Acumulación estacional de una deshidrina de 47-kDa en hojas y cambios en su actividad crioprotectora en Nothofagus dombeyi (Mirb.) Blume

Nothofagus dombeyi (Mirb.) Blume is an evergreen tree, pioneer in habitats subject to unfavorable environmental conditionsas nighttime freezing temperatures and low water content. It inhabits zones characterized by cold Winter with freezingtemperature and Spring frosts reaching to -5ºC. Furthermore, it has the capacity to maintain a functional photosyntheticapparatus at low temperatures. We postulated that N. dombeyi is capable to accumulate dehydrins in leaves in response tocold. Seasonal variation in dehydrins, soluble total proteins, and cryoprotective activity in vitro of protein extracts of N.dombeyi leaves were analyzed during the years 2004 and 2005. A dehydrin-like protein of 47-kDa was immunologicallyidentified; this protein was present only in Winter and Spring. The highest accumulation of this protein and the maximalin vitro cryoprotective activity was found during Spring. The leaf total protein extract of this season preserved the 100%of lactate dehydrogenase (LDH) enzyme activity after 5 freeze/thaw cycles in liquid nitrogen adding 10 ?g/ml of totalproteins extract. The soluble protein concentration increased from 1.8 mg/g in Summer to 4.8 mg/g in Fall on base offresh weight, and declined through Winter and Spring. The 47-kDa dehydrin may be related to cold hardiness of leaftissue in overwintering N. dombeyi. We conclude that cell dehydration caused by freezing is the main factor involved inthe triggering of 47-kDa dehydrin accumulation in leaves of N. dombeyi. The accumulation of reactive oxygen species(ROS) by oxidative stress product of high irradiance and frosts during Spring, and their role in the triggering of the 47-kDadehydrin accumulation in leaves of N. dombeyi is discussed.Nothofagus dombeyi (Mirb.) Blume es un árbol siempreverde, pionero en sitios con condiciones ambientales desfavorablescomo baja temperatura nocturna y baja disponibilidad hídrica. Habita en zonas caracterizadas por inviernos fríos contemperaturas congelantes y heladas de primavera que pueden llegar a los -5ºC. Además tiene la capacidad de mantenersu aparato fotosintético funcional en condiciones de baja temperatura. Postulamos que N. dombeyi es capaz de acumulardeshidrinas en sus hojas en respuesta a baja temperatura. Se analizó la variación estacional de deshidrinas, proteínas solublestotales y la actividad crioprotectora in vitro de extractos proteicos de hojas de N. dombeyi durante los años 2004 y 2005. Unaproteína con características de deshidrina de 47 kDa de peso molecular fue identificada inmunológicamente en hojas, la queestuvo presente sólo en invierno y primavera. La mayor acumulación de esta proteína en las hoja y la máxima crioprotecciónin vitro fue encontrada durante la estación de primavera. El extracto total de proteínas de esta estación conservó el 100% dela actividad de la enzima lactato deshidrogenasa (LDH) después de 5 ciclos de congelamiento/descongelamiento en nitrógenolíquido agregando 10 ?g/ml de extracto total de proteínas. La concentración de proteínas solubles totales aumentó de 1,8 mgpor gramo de peso fresco en verano a 4,8 mg en otoño, y disminuyó durante el invierno y la primavera. La deshidrina de 47kDa podría estar relacionada al endurecimiento por frío del tejido foliar en individuos de N. dombeyi durante el invierno,aumentando su resistencia al congelamiento. Concluimos que la deshidratación celular producida por congelamiento sería elprincipal factor en estimular la acumulación de esta deshidrina de 47kDa en hojas de N. dombeyi. La acumulación de especiesreactivas de oxígeno (ROS) por estrés oxidativo producto de la alta irradiancia y heladas durante la primavera y su papel en elgatillamiento de la acumulación de esta deshidrina de 47 kDa en las hojas es discutida

Conductancia hidráulica foliar y vulnerabilidad a la cavitación disminuyen con la altitud en Phacelia secunda J.F. Gmel. (Boraginaceae)

High mountain ecosystems are characterized by freezing temperatures. Freeze-thaw events can induce embolism in plant xylem. Therisk of embolism increases with the conduit diameter, because wider xylem vessels can contain larger amounts of dissolved gas thatafter water freeze may form big bubbles producing cavitation. Thus smaller vessels could be advantageous in habitats prone to freezingevents. However, smaller conduits decrease hydraulic conductance. The leaf hydraulic conductance (Kf) is a measure of the efficiencyin the water transport across the leaf, and it is defined as the ratio between the water flux across the leaf and the difference of hydraulicpotential across the leaf. Apparently, Kf is a bottleneck for hydraulic conductance of the whole plant and probably also a crucial factorin gas exchange. In this work we evaluated how the elevational origin of P. secunda can affect the hydraulic conductance of the leaf andthe cavitation vulnerability of the vessels. We postulate that plants of P. secunda from higher elevations, as exposed to higher frequencyof freezing events, have minor vessels diameter and lower Kf than plants from lower elevations. To test our hypothesis, we determinedunder field conditions the leaf hydraulic conductance (Kf), in plants from an altitudinal gradient (1,600, 2,800 and 3,600 m) in the central Chilean Andes. In addition, we analyzed cross sections of petiole and leaf lamina to evaluate the changes in the number, sizeand frequency of xilematic vessels in order to determine a cavitation vulnerability index. We found a negative correlation between thehydraulic conductance of the leaf and elevation in P. secunda plants. This is related to the smaller diameter of xylem vessels found inplants higher altitude, which results in a reduced vulnerability to cavitation. These changes could be considered as adaptives, because athigh elevations freezing events are more frequent, and hence, there is a higher probability of cavitation than at low elevations. However,this can negatively effect stomatal conductance and carbon assimilation, restricting the photosynthetic responses of these plants.Los ecosistemas de alta montaña se caracterizan por presentar temperaturas bajo cero durante gran parte del año. Estos episodiosde temperaturas bajo cero podrían inducir embolismo en las plantas que habitan estos ecosistemas ya que durante el congelamientose generan burbujas de aire, las que pueden expandirse durante el descongelamiento conduciendo a la cavitación. La probabilidadde embolismo o cavitación en un conducto xilemático es inversamente proporcional a su diámetro. Sin embargo, la reducción deldiámetro de los vasos, por pequeña que sea, disminuye considerablemente la conductividad de éstos. La conductancia hidráulica de lahoja (Kf) está definida como la proporción entre el flujo de agua a través de la hoja y la diferencia de potencial hídrico a través de esta.Kf es un cuello de botella para la conductancia hidráulica de la planta completa y probablemente es también uno de los factores másdeterminantes en el intercambio de gases. Dado que la intensidad y frecuencia de temperaturas congelantes cambia con la altitud, esimportante estudiar cómo influye la altitud de procedencia de las plantas en la estructura e hidráulica de la hoja y las consecuencias deesto en las probabilidades de embolismo. En este trabajo aprovechamos la amplia distribución altitudinal de la hierba perenne Phaceliasecunda para evaluar cómo cambia la conductividad hidráulica de la hoja y la vulnerabilidad a la cavitación con la altitud. Postulamosque en plantas de P. secunda provenientes de mayores altitudes, al estar expuestas a una mayor frecuencia de eventos congelantes,tienen un menor diámetro de vasos y con ello una disminución en la Kf comparado con plantas provenientes de menor altitud. Paraevaluar esta hipótesis se determinó la conductancia hidráulica foliar (Kf) en plantas provenientes de diferentes altitudes (1.600, 2.800y 3.600 m) en los Andes de Chile Central. Además, se realizaron cortes transversales de pecíolo y lámina para evaluar las variacionesen el número, tamaño y frecuencia de los conductos xilemáticos, y se determinó el índice de vulnerabilidad a la cavitación. Se encontróuna correlación negativa entre la conductancia hidráulica de la hoja y la altitud. Lo anterior se relaciona con los menores diámetros devasos xilemáticos encontrados en las plantas de mayor altitud, lo que trae como consecuencia una menor vulnerabilidad a la cavitaciónen dichas plantas. Lo anterior sugiere una ventaja adaptativa para estas plantas ya que a mayor elevación existe una mayor frecuenciade heladas y en consecuencia mayores probabilidades de cavitación. Sin embargo, esto podría tener un efecto negativo en las tasas deconductancia estomática y asimilación de carbono, disminuyendo el desempeño de estas plantas

Cloning and constitutive expression of Deschampsia antarctica Cu/Zn superoxide dismutase in Pichia pastoris

<p>Abstract</p> <p>Background</p> <p><it>Deschampsia antarctica </it>shows tolerance to extreme environmental factors such as low temperature, high light intensity and an increasing UV radiation as result of the Antarctic ozone layer thinning. It is very likely that the survival of this species is due to the expression of genes that enable it to tolerate high levels of oxidative stress. On that account, we planned to clone the <it>D. antarctica </it>Cu/ZnSOD gene into <it>Pichia pastoris </it>and to characterize the heterologous protein.</p> <p>Findings</p> <p>The Copper/Zinc superoxide dismutase (Cu/ZnSOD) gene, <it>SOD </it>gene, was isolated from a <it>D. antarctica </it>by cDNA library screening. This <it>SOD </it>gene was cloned in the expression vector pGAPZαA and successfully integrated into the genome of the yeast <it>P. pastoris </it>SMD1168H. A constitutive expression system for the expression of the recombinant SOD protein was used. The recombinant protein was secreted into the YPD culture medium as a glycosylated protein with a 32 mg/l expression yield. The purified recombinant protein possesses a specific activity of 440 U/mg.</p> <p>Conclusion</p> <p><it>D. antarctica </it>Cu/ZnSOD recombinant protein was expressed in a constitutive system, and purified in a single step by means of an affinity column. The recombinant SOD was secreted to the culture medium as a glycoprotein, corresponding to approximately 13% of the total secreted protein. The recombinant protein Cu/ZnSOD maintains 60% of its activity after incubation at 40°C for 30 minutes and it is stable (80% of activity) between -20°C and 20°C. The recombinant SOD described in this study can be used in various biotechnological applications.</p

Warmer Temperatures Affect the in situ Freezing Resistance of the Antarctic Vascular Plants

Although positive effects on growth and reproduction of Antarctic vascular plants have been reported under warmer temperatures, it could also increase the vulnerability of these plants to freezing. Thus, we assessed in situ whether warming decreases the freezing resistance of Colobanthus quitensis and Deschampsia antarctica, and we compared the level and mechanism of freezing resistance of these species in the field with previous reports conducted in lab conditions. We assessed the freezing resistance of C. quitensis and D. antarctica by determining their low temperature damage (LT50), ice nucleation temperature (NT) and freezing point (FP) in three sites of the King George Island. Plants were exposed during two growing seasons to a passive increase in the air temperature (+W). +W increased by 1K the mean air temperatures, but had smaller effects on freezing temperatures. Leaf temperature of both species was on average 1.7K warmer inside +W. Overall, warming decreased the freezing resistance of Antarctic species. The LT50 increased on average 2K for C. quitensis and 2.8K for D. antarctica. In contrast, NT and FP decreased on average c. 1K in leaves of warmed plants of both species. Our results showed an averaged LT50 of -15.3°C for C. quitensis, and of -22.8°C for D. antarctica, with freezing tolerance being the freezing resistance mechanism for both species. These results were partially consistent with previous reports, and likely explanations for such discrepancies were related with methodological differences among studies. Our work is the first study reporting the level and mechanisms of freezing resistance of Antarctic vascular plants measured in situ, and we demonstrated that although both plant species exhibited a great ability to cope with freezing temperatures during the growing season, their vulnerability to suffer freezing damage under a warming scenario increase although the magnitude of this response varied across sites and species. Hence, freezing damage should be considered when predicting changes in plant responses of C. quitensis and D. antarctica under future climate conditions of the Antarctic Peninsula

Effects of transcranial static magnetic field stimulation over the left dorsolateral prefrontal cortex on random number generation

OBJECTIVE: Focal application of transcranial static magnetic field stimulation (tSMS) is a neuromodulation technique, with predominantly inhibitory effects when applied to the motor, somatosensory or visual cortex. Whether this approach can also transiently interact with dorsolateral prefrontal cortex (DLPFC) function remains unclear. The suppression of habitual or competitive responses is one of the core executive functions linked to DLPFC function. This study aimed to assess the impact of tSMS on the prefrontal contributions to inhibitory control and response selection by means of a RNG task. METHODS: We applied 20 min of tSMS over the left DLPFC of healthy subjects, using a real/sham cross-over design, during performance of a RNG task. We used an index of randomness calculated with the measures of entropy and correlation to assess the impact of stimulation on DLPFC function. RESULTS: The randomness index of the sequences generated during the tSMS intervention was significantly higher compared to those produced in the sham condition. CONCLUSIONS: Our results indicate that application of tSMS transiently modulates specific functional brain networks in DLPFC, which indicate a potential use of tSMS for treatment of neuropsychiatric disorders. SIGNIFICANCE: This study provides evidence for the capacity of tSMS for modulating DLPFC function

Programa para el entrenamiento de la actividad cognitiva en el adulto mayor

According to demographic studies it is estimated that in 2020 the proportion of the number of elderly will be 20-25%. This aging of the population causes a notable increase in the diseases linked to aging. It has been suggested that the Cognitive Reserve is a mechanism that links high levels of learning, physical exercise and cognitive activity with a lower risk of suffering from a neurodegenerative process. The research aims to implement a program of study and training of cognitive activity in the elderly. It shows as a result the application of the program for the study and training of cognitive activity in the elderly, causing changes in aspects such as operating memory, attention, and speed of processing and executive function of the participants in the program.Según los estudios demográficos se calcula que en el año 2020 la proporción del número de ancianos será del 20 al 25%. Este envejecimiento de la población provoca un incremento notable de las enfermedades ligadas a la ancianidad. Se ha sugerido que la reserva cognitiva es un mecanismo que vincula los niveles altos de aprendizaje, ejercicio físico y actividad cognitiva con un menor riesgo de padecer un proceso neurodegenerativo. La investigación tiene como objetivo instrumentar un programa de estudio y entrenamiento de la actividad cognitiva en el adulto mayor. Se muestra como resultado la aplicación del programa en el estudio y entrenamiento de la actividad cognitiva en el adulto mayor, provocando cambios en aspectos como la memoria operativa, la atención, la velocidad de procesamiento y la función ejecutiva de los participantes en el programa

A high-throughput method for measuring critical thermal limits of leaves by chlorophyll imaging fluorescence

Plant thermal tolerance is a crucial research area as the climate warms and extreme weather events become more frequent. Leaves exposed to temperature extremes have inhibited photosynthesis and will accumulate damage to PSII if tolerance thresholds are exceeded. Temperature-dependent changes in basal chlorophyll fluorescence (T-F0) can be used to identify the critical temperature at which PSII is inhibited. We developed and tested a high-throughput method for measuring the critical temperatures for PSII at low (CTMIN) and high (CTMAX) temperatures using a Maxi-Imaging fluorimeter and a thermoelectric Peltier plate heating/cooling system. We examined how experimental conditions of wet vs dry surfaces for leaves and heating/cooling rate, affect CTMIN and CTMAX across four species. CTMAX estimates were not different whether measured on wet or dry surfaces, but leaves were apparently less cold tolerant when on wet surfaces. Heating/cooling rate had a strong effect on both CTMAX and CTMIN that was species-specific. We discuss potential mechanisms for these results and recommend settings for researchers to use when measuring T-F0. The approach that we demonstrated here allows the high-throughput measurement of a valuable ecophysiological parameter that estimates the critical temperature thresholds of leaf photosynthetic performance in response to thermal extremes.This research was supported by the Australian Research Council (DP170101681)

Brain-Derived Neurotrophic Factor Levels in Cord Blood from Growth Restricted Fetuses with Doppler Alteration Compared to Adequate for Gestational Age Fetuses

Background and Objectives: Fetal growth restriction (FGR) is a severe obstetric disease characterized by a low fetal size entailing a set of undesired consequences. For instance, previous studies have noticed a worrisome association between FGR with an abnormal neurodevelopment. However, the precise link between FGR and neurodevelopmental alterations are not yet fully understood yet. Brain-derived neurotrophic factor (BDNF) is a critical neurotrophin strongly implicated in neurodevelopmental and other neurological processes. In addition, serum levels of BDNF appears to be an interesting indicator of pathological pregnancies, being correlated with the neonatal brain levels. Therefore, the aim of this study is to analyze the blood levels of BDNF in the cord blood from fetuses with FGR in comparison to those with weight appropriate for gestational age (AGA). Materials and Methods: In this study, 130 subjects were recruited: 91 in group A (AGA fetuses); 39 in group B (16 FGR fetuses with exclusively middle cerebral artery (MCA) pulsatility index (PI) 95th percentile). Serum levels of BDNF were determined through ELISA reactions in these groups. Results: Our results show a significant decrease in cord blood levels of BDNF in FGR and more prominently in those with UA PI >95th percentile in comparison to AGA. FGR fetuses with exclusively decreased MCA PI below the 5th percentile also show reduced levels of BDNF than AGA, although this difference was not statistically significant. Conclusions: Overall, our study reports a potential pathophysiological link between reduced levels of BDNF and neurodevelopmental alterations in fetuses with FGR. However, further studies should be conducted in those FGR subjects with MCA PI < 5th percentile in order to understand the possible implications of BDNF in this group.Depto. de Salud Pública y Materno - InfantilFac. de MedicinaTRUEUnión EuropeaComunidad de MadridInstituto de Salud Carlos IIIHalekulani S.LFundación Santiago Dexeus Fontpu

Newborns of Mothers with Venous Disease during Pregnancy Show Increased Levels of Lipid Peroxidation and Markers of Oxidative Stress and Hypoxia in the Umbilical Cord

The study (FIS-PI18/00912) was supported by the Instituto de Salud Carlos III (grant no. Estatal de I + D + I 2013–2016) and co-financed by the European Development Regional Fund “A way to achieve Europe” and B2017/BMD-3804 MITIC-CM (Comunidad de Madrid), and Halekulani S.L.Chronic venous disease (CVD) encompasses a set of disorders of the venous system that have a high prevalence in Western societies and are associated with significant sociohealth costs. Pregnancy is a period in which different hormonal and haemodynamic changes occur that lead to significant changes in the cardiovascular system, increasing the risk of developing venous problems, especially during the third trimester of gestation. In turn, CVD involves a series of local and systemic alterations that can have negative repercussions in pregnancy. In this context, the role of oxidative stress in the pathophysiology of this condition has been shown to significantly affect other vascular structures during pregnancy, such as the placenta. However, the effects of oxidative stress on the umbilical cord in women with CVD have not yet been fully elucidated. Thus, the objective of this study was to analyse the gene and protein expression of the enzymes NOX-1, NOX-2 and iNOS, which are involved in the production of reactive oxygen and nitrogen species, respectively. Similarly, the presence of hypoxia-inducible factor 1-alpha (HIF-1α) in the umbilical cord in women with CVD was compared to that of pregnant control women, and the levels of the lipid peroxidation marker malonyldialdehyde (MDA) in cord tissue and blood was also analysed. Our results support a significant increase in the enzymes NOX-1, NOX-2 and iNOS and HIF-1α and MDA in the umbilical cord tissue and blood of women with CVD. For the first time, our work demonstrates an increase in oxidative stress and cellular damage in the umbilical cords of pregnant women who develop this condition, deepening the understanding of the consequences of CVD during pregnancy.Depto. de Salud Pública y Materno - InfantilFac. de MedicinaTRUEUnión EuropeaComunidad de MadridInstituto de Salud Carlos IIIHalekulanipu

Effects of Sex, Age and Height on Symphysis–Ischial Spine Distance Measured on a Pelvic CT

Objective: To examine the influence of age, sex and height on the symphysis–ischial spine distance (SID) measured on pelvic Computed tomography (CT)images in subjects of reproductive age, and to determine the interobserver reproducibility. This measurement (SID) is of great importance because the use of intrapartum ultrasound is based on the assumption of a specific value (30 mm) of such a measurement. Methods: This was a cross-sectional descriptive study in which SID was measured in subjects aged 20 to 44 years who had been scheduled for pelvic CT at our centre from January 2018 to May 2021 for different reasons. Radiographic measurements of the pelvis were obtained through the multiplanar reconstruction of the CT image. The images obtained from all of the participants were independently assessed by three senior radiologists, and the SID measurements made by each one were blinded from those of the remaining observers. Correlations between the SID and patient age, height and sex were analyzed by univariate and multivariate linear regression. Results: The mean SID for 87 of the enrolled participants (45 women, 42 men) was 28.2 ± 6.25 mm. Among the observers, the mean difference in this distance was 1 to 2 mm, and was scarcely related to measurement size, with agreement being greater than 70%. The mean SID was significantly related to sex and height (SID = −24.9 − 6.51 × sex (0 or 1) + 0.34 × height (cm); p = 0.01; sex equals 1 for a man and 0 for a woman), such that it was a mean of 2.5 mm greater in women than men (29.50 mm vs. 26.99 mm). Conclusion: Measurements of SID on CT images show good interobserver reproducibility, and are related to sex and height.Depto. de Salud Pública y Materno - InfantilFac. de MedicinaTRUEUnión EuropeaComunidad de MadridInstituto de Salud Carlos IIIHalekulani S.L.pu