173 research outputs found
Effect of elevated inorganic carbon on the cytosolic homeostasis of NO3- in the marine angiosperm Posidonia oceanica (L.) Delile
The marine angiosperm Posidonia oceanica is a mediterranean endemism of great ecological significance. As other marine plants, P. oceanica has adapted secondarily to the marine environment and develop anew different mechanisms to colonize it. Among others, this plant has developed a plasma membrane system for the direct uptake of bicarbonate. In this work we have developed both NO3- and Cl- selective microelectrodes for the continuous monitoring of the intracellular (cytosolic) NO3- and Cl-. In the light, leaf mesophyll cells show a cytosolic NO3- concentration of 5.7±0.2 mM (n=10), while in the dark cytosolic NO3- raises up to 8.7±1.1 mM; these values are in the range of concentrations quoted for Arabidopsis thaliana (Cookson et al., 2005). The enrichment of natural seawater (NSW) with 3 mM NaHCO3 caused a decrease of the cytosolic NO3- concentration of 1 mM and a decrease of the cytosolic concentration of Cl- of 3.5 mM. The saturation of NSW with 1000 ”L CO2 L-1 produced a lower diminution of the cytosolic NO3- (0.3 mM). In the presence of 0.1 mM of the plasma membrane permeable inhibitor of the carbonic anhydrase (EZ) the diminution of cytosolic NO3- caused by the same concentration of CO2 was much lower, 0.1 mM. The addition of inorganic carbon, either HCO3- or CO2, has an effect on the cytosolic mechanisms for anionic homeostasis, one of which is the opening of the slow anion channels. These channels are permeable to NO3- and Cl- and could elicit the efflux of these ions. In P. oceanica, the response in the presence of EZ points out that the inorganic carbon species that cause the NO3-/Cl- efflux is HCO3-. This effect could contribute to plant biomass N dilution observed in elevated CO2.
References:
Cookson et al. 2005. Plant Physiology 138, 1097â1105.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tec
HCO3- enrichment causes cytosolic NO3- efflux in Posidonia oceanica leaf cells
Posidonia oceanica is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment, characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate or phosphate. In addition, in aquatic environments the supply of CO2 for the photosynthesis is limited by diffusion and therefore many aquatic plants use HCO3- as the inorganic carbon source for photosynthesis. Previous results have shown that Na+ -dependent transport systems operate on the plasma membrane of P. oceanica mesophyll leaf cells for the high-affinity NO3-, Pi or amino acids uptake. Also, a direct transport of HCO3- driven by H+ has been found in this species that provides inorganic carbon for photosynthesis and could be a significant component of a carbon concentrating mechanism in this species. Interestingly, this HCO3- direct uptake caused the efflux of chloride from the cytosol, probably through S-type anion channels, pointing that other anions could also be removed from the cytosol. This hypothesis could be relevant in the case of NO3-, since the decrease of cytosolic NO3- in response to HCO3- enrichment could limit N-assimilation. Here we analyse the effect of HCO3- increase on NO3- uptake and cytosolic homeostasis in P. oceanica. Enrichment of natural seawater with 3 mM HCO3- evokes the on-going decrease of cytosolic NO3-, from 5.7 ± 0.2 to 4.8 ± 0.7 mM after 40 min of treatment. The incubation of P. oceanica leaf pieces in 3 mM HCO3- NSW causes an initial increase of NO3- concentration in the medium. Maximum efflux (21 nmol NO3- gFM-1 min-1) occurs within the first minute of incubation. Then, external NO3- is depleted from the medium at lower net uptake rate than the value observed in non HCO3- -enriched natural seawater. These results fit the hypothesis that HCO3- enrichment causes the nitrogen loose and could impair nitrogen assimilation promoting N biomass impoverishment.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech.
Spanish MINECO, projects BFU2017-85117-R and BIO2016-81957-RED
Na+-dependent NO3- uptake in leaf cells of the seagrass Posidonia oceanica (L.) Delile
Posidonia oceanica (L.) Delile is an endemic Mediterranean seagrass of recognized ecological significance and, as other seagrasses, this species has secondarily adapted to live in the marine environment. In this alkaline medium with a high Na+ concentration (0.5 M), the high inwardly directed electrochemical potential gradient for sodium is used in the seagrass Zostera marina to energize the uptake of nitrate1 and phosphate that usually occur at concentration below 10 ”M. Here we summarize several evidences for the operation of a sodium-dependent high-affinity nitrate transport system at the plasma membrane of the mesophyll leaf cells of P. oceanica.
Leaf cells of P. oceanica possess a H+-ATPase as a primary pump, exhibit a plasma membrane potential (Em) of -174 ± 10 mV and show reduced Na+ permeability. The addition of micromolar nitrate concentrations induces membrane depolarizations that show saturation kinetics. Curve fitting of the values renders a semisaturation constant (Km) of 21.3 ± 6.6 ΌM and a maximum depolarization (Dmax) of 7 ± 1 mV. In dark conditions, Dmax decreases by fifty percent but no significant effect is observed on the Km value. On the other hand, nitrate induced depolarizations show sodium dependence. The depolarizations induced by 100 ”M NO3- in media containing increasing Na+ concentrations (from 0 to 250 mM) show saturation kinetics, rendering a Km value of 16 ± 5 mM Na+. Moreover, the depolarization induced by 100 ”M NO3- is accompanied by a simultaneous increase of cytosolic sodium, measured by Na+-sensitive microelectrodes, of 0.4 ± 0.2 mM above the resting cytosolic sodium concentration (17 ± 2 mM).
Finally, nitrate uptake rates, measured in depletion experiments, decreases by 50% and 80% in dark conditions and in the absence of Na+, respectively, compared with control conditions (0.5 M Na+ and light).
All together, these results strongly suggest that NO3- uptake in P. oceanica leaf cells is mediated by a high-affinity nitrate carrier that uses Na+ as the driving ion.
1 Rubio et al. (2005). J. Exp. Bot, 412: 613-622.
Project Funding: CTM 2011-30356. (MEC)Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
The problem of living in the sea: the uptake of inorganic carbon and nutrients in Posidonia oceanica (L.) Delile
The genus Posidonia exhibits a peculiar geographical distribution. It is composed by nine species, eight of which are distributed along the Australian coasts and only one, Posidonia oceanica (L.) Delile, is a Mediterranean endemism. Like other angiosperms, P. oceanica has adapted secondarily to the marine environment, and has developed anew mechanisms to face a liquid and alkaline medium (pH 8.2) that contains a high salt concentration (0.5 M NaCl). The liquid environment limits the diffusive flow of CO2 and nutrients and, furthermore, CO2 dissolves in water and forms HCO3-, the more abundant chemical species of inorganic carbon at pH 8.2.
Like other green plants P. oceanica uses CO2 for photosynthesis. In addition, this species shows a transport system in the plasma membrane for the direct uptake of HCO3-, that uses H+ as the driving ion. The addition of HCO3- provokes a transient hyperpolarization of the plasma membrane followed by a depolarization; at the same time, the cytosolic pH (pHc) becomes transiently acidic and next it gets alkaline, and remains alkaline throughout the HCO3- pulse. The alkalinization of the pHc is due to the cytosolic accumulation of HCO3- and OH- and it is sensitive to the addition of ethoxyzolamide, an inhibitor of the internal carbonic anhydrase. The increase of negative charges in the cytosol triggers the release of Cl- to recover the values of the resting membrane potential. The plasmalemma of P. oceanica exhibits a reduced Na+ permeability and shows a H+/Na+ antiporter activity that keeps low and relatively constant the cytosolic Na+ concentration (17 mM Na+). The inside negative membrane potential (-178 mV) and the low [Na+]c generate a tremendous Na+-motive force that this plant uses for the high affinity transport of NO3- (Km= 21 ”M), and of the amino acids alanine (Km= 37 ”M) and cysteine (Km= 10 ”M). The uptake of these compounds shows a strict dependence on the presence of Na+ in the medium. Moreover, the addition of micromolar concentrations of NO3-, alanine or cysteine gives rise to millimolar increments of [Na+]c. Experiments with external LIX pH mini-electrodes show that the uptake of glucose is not Na+ but H+ dependent. Thus, the model for the ion transport energization in this species seems to be mixed, with a H+-ATPase as the primary pump and a series of carriers that use H+ (HCO3-, Na+, glucose) or Na+ (NO3-, amino acids) as the driving ion.
Project Funding: CTM 2011-30356 (MEC)Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
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Short-Term Response of Cytosolic N O 3 - to Inorganic Carbon Increase in Posidonia oceanica Leaf Cells.
The concentration of CO2 in the atmosphere has increased over the past 200 years and is expected to continue rising in the next 50 years at a rate of 3 ppm·year-1. This increase has led to a decrease in seawater pH that has changed inorganic carbon chemical speciation, increasing the dissolved HC O 3 - . Posidonia oceanica is a marine angiosperm that uses HC O 3 - as an inorganic carbon source for photosynthesis. An important side effect of the direct uptake of HC O 3 - is the diminution of cytosolic Cl- (Cl-c) in mesophyll leaf cells due to the efflux through anion channels and, probably, to intracellular compartmentalization. Since anion channels are also permeable to N O 3 - we hypothesize that high HC O 3 - , or even CO2, would also promote a decrease of cytosolic N O 3 - ( N O 3 - c ). In this work we have used N O 3 - - and Cl--selective microelectrodes for the continuous monitoring of the cytosolic concentration of both anions in P. oceanica leaf cells. Under light conditions, mesophyll leaf cells showed a N O 3 - c of 5.7 ± 0.2 mM, which rose up to 7.2 ± 0.6 mM after 30 min in the dark. The enrichment of natural seawater (NSW) with 3 mM NaHCO3 caused both a N O 3 - c decrease of 1 ± 0.04 mM and a Cl c - decrease of 3.5 ± 0.1 mM. The saturation of NSW with 1000 ppm CO2 also produced a diminution of the N O 3 - c , but lower (0.4 ± 0.07 mM). These results indicate that the rise of dissolved inorganic carbon ( HC O 3 - or CO2) in NSW would have an effect on the cytosolic anion homeostasis mechanisms in P. oceanica leaf cells. In the presence of 0.1 mM ethoxyzolamide, the plasma membrane-permeable carbonic anhydrase inhibitor, the CO2-induced cytosolic N O 3 - diminution was much lower (0.1 ± 0.08 mM), pointing to HC O 3 - as the inorganic carbon species that causes the cytosolic N O 3 - leak. The incubation of P. oceanica leaf pieces in 3 mM HC O 3 - -enriched NSW triggered a short-term external N O 3 - net concentration increase consistent with the N O 3 - c leak. As a consequence, the cytosolic N O 3 - diminution induced in high inorganic carbon could result in both the decrease of metabolic N flux and the concomitant biomass N impoverishment in P. oceanica and, probably, in other aquatic plants
Small farmers' perception of factors influencing regional chemical control of Diaphorina citri
Regional Control Areas (RCAs) have been implemented in Mexico as a strategy to delay the spread of Candidatus Liberibacter asiaticus, the causal bacterium of the disease known as Huanglongbing (HLB). The implementation of an effective management of the vector insect, Diaphorina citri in the RCAs requires the knowledge, acceptance and coordinated engagement of small agricultural producers. This research assessed the perception and knowledge of 62 citrus growers regarding the operational, sociocultural and environmental factors influencing chemical control of D. citri in four RCAs within Veracruz State. According to their responses, the following factors have been identified as the operational factors with the highest influence on the effectiveness of insecticides against D. citri within RCAs: the lack of knowledge about the use of surfactants, application speed, poor calibration of sprayers and incorrect water quality. The most significant sociocultural factors are the general unawareness of the pest and the safe and proper application of pesticides. The most relevant environmental factors during application: temperature, relative humidity, and wind speed. Sociocultural index correlated with the perception of effectiveness. Therefore, it becomes necessary to consider differences among citrus growers in each region and setting out the most appropriatestrategies for vector and disease management.
Highlights
Some operational practices that citrus growers are not aware of may influence their perception of chemical control.
The sociocultural context of growers determines their decision-taking on insecticide applications.
During the application of insecticides in regional control areas (RCAs), growers do not take into account weather conditions.
The effective management of D. citri requires a coordinated engagement of small growers' in RCAs.Regional Control Areas (RCAs) have been implemented in Mexico as a strategy to delay the spread of Candidatus Liberibacter asiaticus, the causal bacterium of the disease known as Huanglongbing (HLB). The implementation of an effective management of the vector insect, Diaphorina citri in the RCAs requires the knowledge, acceptance and coordinated engagement of small agricultural producers. This research assessed the perception and knowledge of 62 citrus growers regarding the operational, sociocultural and environmental factors influencing chemical control of D. citri in four RCAs within Veracruz State. According to their responses, the following factors have been identified as the operational factors with the highest influence on the effectiveness of insecticides against D. citri within RCAs: the lack of knowledge about the use of surfactants, application speed, poor calibration of sprayers and incorrect water quality. The most significant sociocultural factors are the general unawareness of the pest and the safe and proper application of pesticides. The most relevant environmental factors during application: temperature, relative humidity, and wind speed. Sociocultural index correlated with the perception of effectiveness. Therefore, it becomes necessary to consider differences among citrus growers in each region and setting out the most appropriatestrategies for vector and disease management.
Highlights
Some operational practices that citrus growers are not aware of may influence their perception of chemical control.
The sociocultural context of growers determines their decision-taking on insecticide applications.
During the application of insecticides in regional control areas (RCAs), growers do not take into account weather conditions.
The effective management of D. citri requires a coordinated engagement of small growers' in RCAs
The pulsating nature of large-scale Saharan dust transport as a result of interplays between mid-latitude Rossby waves and the North African Dipole Intensity
It was previously shown that during August the export of Saharan dust to the Atlantic was strongly
affected by the difference of the 700-hPa geopotential height anomaly between the subtropics and the
tropics over North Africa, which was termed the North African Dipole Intensity (NAFDI). In this work a
more comprehensive analysis of the NAFDI is performed, focusing on the entire summer dust season
(JuneeSeptember), and examining the interactions between the mid-latitude Rossby waves (MLRWs)
and NAFDI. Widespread and notable aerosol optical depth (AOD) monthly anomalies are found for each
NAFDI-phase over the dust corridors off the Sahara, indicating that NAFDI presents intra-seasonal
variability and drives dust transport over both the Mediterranean basin and the North Atlantic. Those
summer months with the same NAFDI-phase show similar AOD-anomaly patterns. Variations in NAFDIphase
also control the displacement of the Saharan Heat Low (SHL) westwards or eastwards through
horizontal advection of temperature over Morocco-Western Sahara or eastern Algeria-Western Libya,
respectively. The connection between the SHL and the NAFDI is quantified statistically by introducing
two new daily indexes that account for their respective phases (NAFDI daily index -NAFDIDI-, and SHL
longitudinal shift index -SHLLSI-) and explained physically using the energy equation of the atmospheric
dynamics. The Pearson's correlation coefficient between the oneeday-lag SHLLSI and the NAFDIDI for an
extended summer season (1980e2013) is 0.78. A positive NAFDI is associated with the West-phase of the
SHL, dust sources intensification on central Algeria, and positive AOD anomalies over this region and the
Subtropical North Atlantic. A negative NAFDI is associated with the East-phase of the SHL, and positive
AOD anomalies over central-eastern Sahara and the central-western Mediterranean Sea. The results
point out that the phase changes of NAFDI at intra-seasonal time scale are conducted by those MLRWs
that penetrate deeply into the low troposphere.This work is part of the research activities developed by the WMO SDS-WAS Regional Centre for Northern Africa, Middle East and Europe, held by AEMET and BSC-CNS. This study also contributes to Copernicus Atmosphere Monitoring Service (CAMS). Our acknowledgment to ECMWF for providing MACC-dust reanalysis. The authors wish to thank NCEP/NCAR Reanalysis Project. We acknowledge NASA LADS for providing MODIS data. The University of Granada (Spain) and its âPhysics and Space Sciencesâ PhD Programme are acknowledged by A. J. GĂłmez-PelĂĄez and E. Cuevas. AEROATLAN project (CGL2015-17 66229-P), co-funded by the Ministry of Economy and Competitiveness of Spain and the European Regional Development Fund contributed to this study. Sara Basart acknowledges the CICYT project (CGL2013-46736
Pivotal role of the North African Dipole Intensity (NAFDI) on alternate Saharan dust export over the North Atlantic and the Mediterranean, and relationship with the Saharan Heat Low and mid-latitude Rossby waves [Discussion paper]
In this study, we revise the index that quantifies the North African Dipole Intensity (NAFDI), and explain its relationship with the Saharan Heat Low (SHL) and mid-latitude Rossby waves. We find outstanding similarities of meteorological patterns associated with the positive NAFDI and the SHL West-phase on the one hand, and with the negative NAFDI and the SHL East-Phase, on the other hand. We introduce the daily NAFDI index and the daily SHL West-East Displacement Index (SHLWEDI). The Pearson correlation coefficient between the daily SHLWEDI 1-day lagged and the daily NAFDI for the period 1980â2013 20 Juneâ17 September is fairly high (r = 0.77). The correlation reduces to 0.69 if the SHLWEDI is not lagged. We observe that the SHL West-phase is significantly more frequent than the SHL East-phase, and that the SHL is more intense during its East-phase.Part of this study was performed in the frame of AEROATLAN (grant 2015-66229), funded by the Ministry of Economy and Competitiveness of Spain
Propiedades fiÌsico-quiÌmicas de jamones elaborados con carne paÌlida, suave y exudativa de cerdo
Los objetivos del presente estudio fueron evaluar las propiedades fiÌsico-quiÌmicas de jamones elaborados con 0, 10 y 20% de carne de cerdo con caracteriÌsticas paÌlida, suave y exudativa, asiÌ como determinar el rendimiento en jamoÌn al adicionar carragenina como agente ligador. Los datos fueron analizados estadiÌsticamente en un disenÌo de cuadro latino con cuatro repeticiones por tratamiento en el experimento 1 y tres en el experimento 2, y las medias fueron sometidas a contrastes ortogonales. No hubo efecto (P>0.05) de los porcentajes de carne paÌlida, suave y exudativa y del almacenamiento en el color, pH, esfuerzo de corte, capacidad de retencioÌn de agua y proteiÌna total. La calidad sensorial no fue diferente (P>0.05) entre el jamoÌn PSE y el control, no obstante el jamoÌn con el 20% mostroÌ (P>0.05) la mayor peÌrdida por cocimiento y almacenamiento. La adicioÌn de los niveles de carne disminuyoÌ (P0.05). La adicioÌn de carragenina no modificoÌ (P>0.05) la capacidad de retencioÌn de agua, esfuerzo de corte, color y calidad sensorial de los jamones normales y con C-PSE, pero siÌ redujo (P>0.05) la peÌrdida de peso por cocimiento y por almacenamiento. Los resultados sugieren que la adicioÌn de hasta un 20% de C-PSE y carrageninas para los jamones reestructurados no tiene efectos perjudiciales en la calidad del producto.
DOI: https://doi.org/10.54167/tecnociencia.v1i1.32
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