Speedy stomata of a C4 plant correlate with enhanced K+ channel gating.

Stomata are microscopic pores at the surface of plant leaves that facilitate gaseous diffusion to support photosynthesis. The guard cells around each stoma regulate the pore aperture. Plants that carry out C4 photosynthesis are usually more resilient than C3 plants to stress, and their stomata operate over a lower dynamic range of CO2 within the leaf. What makes guard cells of C4 plants more responsive than those of C3 plants? We used gas exchange and electrophysiology, comparing stomatal kinetics of the C4 plant Gynandropsis gynandra and the phylogenetically related C3 plant Arabidopsis thaliana. We found, with varying CO2 and light, that Gynandropsis showed faster changes in stomata conductance and greater water use efficiency when compared with Arabidopsis. Electrophysiological analysis of the dominant K+ channels showed that the outward-rectifying channels, responsible for K+ loss during stomatal closing, were characterised by a greater maximum conductance and substantial negative shift in the voltage dependence of gating, indicating a reduced inhibition by extracellular K+ and enhanced capacity for K+ flux. These differences correlated with the accelerated stomata kinetics of Gynandropsis, suggesting that subtle changes in the biophysical properties of a key transporter may prove a target for future efforts to engineer C4 stomatal kinetics.

OnGuard3e: A predictive, ecophysiology-ready tool for gas exchange and photosynthesis research.

Gas exchange across the stomatal pores of leaves is a focal point in studies of plant-environmental relations. Stomata regulate atmospheric exchange with the inner air spaces of the leaf. They open to allow CO2 entry for photosynthesis and close to minimize water loss. Models that focus on the phenomenology of stomatal conductance generally omit the mechanics of the guard cells that regulate the pore aperture. The OnGuard platform fills this gap and offers a truly mechanistic approach with which to analyse stomatal gas exchange, whole-plant carbon assimilation and water-use efficiency. Previously, OnGuard required specialist knowledge of membrane transport, signalling and metabolism. Here we introduce OnGuard3e, a software package accessible to ecophysiologists and membrane biologists alike. We provide a brief guide to its use and illustrate how the package can be applied to explore and analyse stomatal conductance, assimilation and water use efficiencies, addressing a range of experimental questions with truly predictive outputs.

[Addressing HIV/AIDS and syphilis in Venezuelan migrant women from the perspective of health managers in the North of BrazilManejo de la infección por el VIH/sida y la sífilis en mujeres migrantes venezolanas desde la perspectiva de los gestores de salud en el norte de Brasil]. / Enfrentamento de HIV/aids e sífilis em mulheres venezuelanas migrantes na perspectiva de gestores de saúde no Norte do Brasil.

Objective: To identify the perception of health managers regarding the actions taken and the challenges encountered in addressing HIV and syphilis in Venezuelan migrant women in Brazil. Method: This descriptive-exploratory study using a qualitative approach was conducted from January to March 2021 in the municipalities of Boa Vista (state of Roraima) and Manaus (state of Amazonas). Audio interviews with the participants were transcribed in full and examined using thematic content analysis. Results: Ten managers were interviewed (five in Boa Vista and five in Manaus). Content analysis identified the following domains and themes: available infrastructure for diagnosis and treatment of AIDS and syphilis - access, availability of medical appointments /waiting list, training of health teams, and psychosocial support; challenges faced by Venezuelan women - language, documentation issues, and frequent address changes; and strategies and actions adopted and expectations for addressing HIV/AIDS and syphilis in the context of migration. Conclusions: Despite the care provided to Venezuelan women in Brazil - guaranteed by the universal nature of the Brazilian health system - language and lack of documentation remain as barriers. Given the absence of action plans and future planning for the care of migrant women with HIV or syphilis in municipalities, it is important to develop public policies aimed at minimizing the difficulties faced by this population.

Objetivo: Determinar la percepción de los gestores de salud sobre las medidas adoptadas y los desafíos encontrados para manejar la infección por el VIH y la sífilis en mujeres migrantes venezolanas en Brasil. Métodos: Este estudio descriptivo y exploratorio, con enfoque cualitativo, se realizó de enero a marzo del 2021 en los municipios de Boa Vista (estado de Roraima) y Manaos (estado de Amazonas). La grabación de las entrevistas de los participantes se transcribió en su totalidad. El análisis se basó en la técnica de evaluación temática del contenido. Resultados: Se hicieron entrevistas a diez gestores (cinco en Boa Vista y cinco en Manaos). En el análisis del contenido se observaron los siguientes ejes y temas: la estructura disponible para el diagnóstico y tratamiento del sida y de la sífilis, con inclusión de acceso, cupos de atención, filas de espera y formación de equipos de salud y apoyo psicosocial; los desafíos enfrentados por las mujeres venezolanas, como idioma, problemas de documentación y frecuencia de cambio de domicilio; las estrategias y medidas adoptadas y las expectativas para enfrentar la infección por el VIH/sida y la sífilis en el marco de la migración. Conclusiones: A pesar de las medidas de acogida a las mujeres migrantes venezolanas, garantizadas por la universalidad del sistema de salud brasileño, todavía existen algunas barreras como el idioma y la falta de documentación. Ante la falta de planes de acción y planificación futura de la atención a las mujeres migrantes portadoras del VIH o con sífilis en los municipios, es importante formular políticas públicas con el fin de reducir las dificultades enfrentadas por este grupo de la población.

Membrane voltage as a dynamic platform for spatiotemporal signaling, physiological, and developmental regulation.

Membrane voltage arises from the transport of ions through ion-translocating ATPases, ion-coupled transport of solutes, and ion channels, and is an integral part of the bioenergetic "currency" of the membrane. The dynamics of membrane voltage-so-called action, systemic, and variation potentials-have also led to a recognition of their contributions to signal transduction, both within cells and across tissues. Here, we review the origins of our understanding of membrane voltage and its place as a central element in regulating transport and signal transmission. We stress the importance of understanding voltage as a common intermediate that acts both as a driving force for transport-an electrical "substrate"-and as a product of charge flux across the membrane, thereby interconnecting all charge-carrying transport across the membrane. The voltage interconnection is vital to signaling via second messengers that rely on ion flux, including cytosolic free Ca2+, H+, and the synthesis of reactive oxygen species generated by integral membrane, respiratory burst oxidases. These characteristics inform on the ways in which long-distance voltage signals and voltage oscillations give rise to unique gene expression patterns and influence physiological, developmental, and adaptive responses such as systemic acquired resistance to pathogens and to insect herbivory.

Predominant Golgi Residency of the Plant K/HDEL Receptor Is Essential for Its Function in Mediating ER Retention.

Accumulation of soluble proteins in the endoplasmic reticulum (ER) of plants is mediated by a receptor termed ER RETENTION DEFECTIVE2 (ERD2) or K/HDEL receptor. Using two gain-of-function assays and by complementing loss of function in Nicotiana benthamiana, we discovered that compromising the lumenal N terminus or the cytosolic C terminus with fluorescent fusions abolishes its biological function and profoundly affects its subcellular localization. Based on the confirmed asymmetrical topology of ERD2, we engineered a new fluorescent ERD2 fusion protein that retains biological activity. Using this fusion, we show that ERD2 is exclusively detected at the Golgi apparatus, unlike nonfunctional C-terminal fusions, which also label the ER. Moreover, ERD2 is confined to early Golgi compartments and does not show ligand-induced redistribution to the ER. We show that the cytosolic C terminus of ERD2 plays a crucial role in its function. Two conserved leucine residues that do not correspond to any known targeting motifs for ER-Golgi trafficking were shown to be essential for both ERD2 Golgi residency and its ability to mediate ER retention of soluble ligands. The results suggest that anterograde ER to Golgi transport of ERD2 is either extremely fast, well in excess of the bulk flow rate, or that ERD2 does not recycle in the way originally proposed.

Engagement of Men in Antenatal Care Services: Increased HIV Testing and Treatment Uptake in a Community Participatory Action Program in Mozambique.

Uptake of HIV testing and antiretroviral therapy (ART) services during antenatal care (ANC) in rural Mozambique is disappointing. To nurture supportive male engagement in ANC services, we partnered with traditional birth attendants and trained a new type of male-to-male community health agent, "Male Champions", who focused on counseling male partners to create new, male-friendly community norms around engagement in spousal/partner pregnancies. We assessed ANC service uptake using a pre-post intervention design. The intervention was associated with increases in: (1) uptake of provider-initiated counseling and testing among pregnant woman (81 vs. 92 %; p < 0.001); (2) male engagement in ANC (5 vs. 34 %; p < 0.001); and (3) uptake of ART (8 vs. 19 %; p < 0.001). When men accepted HIV testing, rates of testing rose markedly among pregnant women. With the challenges in scale-up of Option B+ in sub-Saharan Africa, similar interventions may increase testing and treatment acceptability during pregnancy.

The K/HDEL receptor does not recycle but instead acts as a Golgi-gatekeeper.

Accurately measuring the ability of the K/HDEL receptor (ERD2) to retain the ER cargo Amy-HDEL has questioned earlier results on which the popular receptor recycling model is based upon. Here we demonstrate that ERD2 Golgi-retention, rather than fast ER export supports its function. Ligand-induced ERD2 redistribution is only observed when the C-terminus is masked or mutated, compromising the signal that prevents Golgi-to-ER transport of the receptor. Forcing COPI mediated retrograde transport destroys receptor function, but introducing ER-to-Golgi export or cis-Golgi retention signals re-activate ERD2 when its endogenous Golgi-retention signal is masked or deleted. We propose that ERD2 remains fixed as a Golgi gatekeeper, capturing K/HDEL proteins when they arrive and releasing them again into a subdomain for retrograde transport back to the ER. An in vivo ligand:receptor ratio far greater than 100 to 1 strongly supports this model, and the underlying mechanism appears to be extremely conserved across kingdoms.

Engineering a K+ channel 'sensory antenna' enhances stomatal kinetics, water use efficiency and photosynthesis.

Stomata of plant leaves open to enable CO2 entry for photosynthesis and close to reduce water loss via transpiration. Compared with photosynthesis, stomata respond slowly to fluctuating light, reducing assimilation and water use efficiency. Efficiency gains are possible without a cost to photosynthesis if stomatal kinetics can be accelerated. Here we show that clustering of the GORK channel, which mediates K+ efflux for stomatal closure in the model plant Arabidopsis, arises from binding between the channel voltage sensors, creating an extended 'sensory antenna' for channel gating. Mutants altered in clustering affect channel gating to facilitate K+ flux, accelerate stomatal movements and reduce water use without a loss in biomass. Our findings identify the mechanism coupling channel clustering with gating, and they demonstrate the potential for engineering of ion channels native to the guard cell to enhance stomatal kinetics and improve water use efficiency without a cost in carbon fixation.

Guard cell endomembrane Ca2+-ATPases underpin a 'carbon memory' of photosynthetic assimilation that impacts on water-use efficiency.

Stomata of most plants close to preserve water when the demand for CO2 by photosynthesis is reduced. Stomatal responses are slow compared with photosynthesis, and this kinetic difference erodes assimilation and water-use efficiency under fluctuating light. Despite a deep knowledge of guard cells that regulate the stoma, efforts to enhance stomatal kinetics are limited by our understanding of its control by foliar CO2. Guided by mechanistic modelling that incorporates foliar CO2 diffusion and mesophyll photosynthesis, here we uncover a central role for endomembrane Ca2+ stores in guard cell responsiveness to fluctuating light and CO2. Modelling predicted and experiments demonstrated a delay in Ca2+ cycling that was enhanced by endomembrane Ca2+-ATPase mutants, altering stomatal conductance and reducing assimilation and water-use efficiency. Our findings illustrate the power of modelling to bridge the gap from the guard cell to whole-plant photosynthesis, and they demonstrate an unforeseen latency, or 'carbon memory', of guard cells that affects stomatal dynamics, photosynthesis and water-use efficiency.

Enfrentamento de HIV/aids e sífilis em mulheres venezuelanas migrantes na perspectiva de gestores de saúde no Norte do Brasil / Addressing HIV/AIDS and syphilis in Venezuelan migrant women from the perspective of health managers in the North of Brazil / Manejo de la infección por el VIH/sida y la sífilis en mujeres migrantes venezolanas desde la perspectiva de los gestores de salud en el norte de Brasil

RESUMO Objetivo. Identificar a percepção dos gestores de saúde sobre as ações adotadas e os desafios encontrados no enfrentamento de HIV e sífilis em mulheres venezuelanas migrantes no Brasil. Métodos. Este estudo descritivo-exploratório, de abordagem qualitativa, foi realizado de janeiro a março de 2021 nos municípios de Boa Vista (estado de Roraima) e Manaus (estado do Amazonas). As entrevistas em áudio realizadas com os participantes foram transcritas na íntegra. A análise foi pautada na técnica de avaliação de conteúdo temática. Resultados. Foram entrevistados 10 gestores (cinco em Boa Vista e cinco em Manaus). A análise de conteúdo identificou os seguintes eixos e temas: estrutura disponível para diagnóstico e tratamento de aids e sífilis — acesso, vagas para atendimento/fila de espera, formação das equipes de saúde e suporte psicossocial; desafios enfrentados pelas mulheres venezuelanas — idioma, questões de documentação e frequência de alteração de endereço; e estratégias e ações adotadas e expectativas para o enfrentamento de HIV/aids e sífilis no contexto de migração. Conclusões. Apesar das ações de acolhimento das mulheres venezuelanas migrantes — garantido pela universalidade do sistema de saúde brasileiro — aspectos como o idioma e a falta de documentação permanecem como barreiras. Diante da inexistência de planos de ação e planejamento futuro da atenção a mulheres migrantes portadoras de HIV ou sífilis nos municípios, é importante desenvolver políticas públicas com o objetivo de minimizar as dificuldades enfrentadas por essa população.

ABSTRACT Objective. To identify the perception of health managers regarding the actions taken and the challenges encountered in addressing HIV and syphilis in Venezuelan migrant women in Brazil. Method. This descriptive-exploratory study using a qualitative approach was conducted from January to March 2021 in the municipalities of Boa Vista (state of Roraima) and Manaus (state of Amazonas). Audio interviews with the participants were transcribed in full and examined using thematic content analysis. Results. Ten managers were interviewed (five in Boa Vista and five in Manaus). Content analysis identified the following domains and themes: available infrastructure for diagnosis and treatment of AIDS and syphilis — access, availability of medical appointments /waiting list, training of health teams, and psychosocial support; challenges faced by Venezuelan women — language, documentation issues, and frequent address changes; and strategies and actions adopted and expectations for addressing HIV/AIDS and syphilis in the context of migration. Conclusions. Despite the care provided to Venezuelan women in Brazil — guaranteed by the universal nature of the Brazilian health system — language and lack of documentation remain as barriers. Given the absence of action plans and future planning for the care of migrant women with HIV or syphilis in municipalities, it is important to develop public policies aimed at minimizing the difficulties faced by this population.

RESUMEN Objetivo. Determinar la percepción de los gestores de salud sobre las medidas adoptadas y los desafíos encontrados para manejar la infección por el VIH y la sífilis en mujeres migrantes venezolanas en Brasil. Métodos. Este estudio descriptivo y exploratorio, con enfoque cualitativo, se realizó de enero a marzo del 2021 en los municipios de Boa Vista (estado de Roraima) y Manaos (estado de Amazonas). La grabación de las entrevistas de los participantes se transcribió en su totalidad. El análisis se basó en la técnica de evaluación temática del contenido. Resultados. Se hicieron entrevistas a diez gestores (cinco en Boa Vista y cinco en Manaos). En el análisis del contenido se observaron los siguientes ejes y temas: la estructura disponible para el diagnóstico y tratamiento del sida y de la sífilis, con inclusión de acceso, cupos de atención, filas de espera y formación de equipos de salud y apoyo psicosocial; los desafíos enfrentados por las mujeres venezolanas, como idioma, problemas de documentación y frecuencia de cambio de domicilio; las estrategias y medidas adoptadas y las expectativas para enfrentar la infección por el VIH/sida y la sífilis en el marco de la migración. Conclusiones. A pesar de las medidas de acogida a las mujeres migrantes venezolanas, garantizadas por la universalidad del sistema de salud brasileño, todavía existen algunas barreras como el idioma y la falta de documentación. Ante la falta de planes de acción y planificación futura de la atención a las mujeres migrantes portadoras del VIH o con sífilis en los municipios, es importante formular políticas públicas con el fin de reducir las dificultades enfrentadas por este grupo de la población.

The Impact of Visual Aids and Enhanced Training on the Delivery of Positive Health, Dignity, and Prevention Messages to Adult Patients Living with HIV in Rural North Central Mozambique.

INTRODUCTION: Positive health, dignity, and prevention (PHDP) interventions target people living with HIV and AIDS (PLHIV) to promote well-being and prevent onward transmission. Concern that increased life expectancy and improved well-being would lead to increased risky sexual behaviour and subsequent HIV transmission motivated researchers to test novel strategies to support treatment adherence, encourage safer sex, STI treatment and partner testing, prevention of mother to child transmission, and support uptake of family planning. METHODS: We assessed the number and type of PHDP messages delivered to PLHIV before and after the implementation of an educational intervention for health providers combined with the distribution of visual job aids and monthly technical assistance. RESULTS: From April 21, 2013 to March 20, 2014, we documented 54,731 clinical encounters at three rural health centres in Zambézia province, Mozambique from 9,248 unique patients. The percentage of patients who received all seven PHDP messages during their last three visits was 1.9% pre-intervention vs. 13.6% post- intervention (p=<0.001). Younger patients (25 years vs. 35) and those with a recent HIV diagnosis (two weeks vs. two years) had higher odds of receiving any PHDP message (Odds Ratio [OR]: 1.22 and 2.79, respectively). Patients >59 days late collecting medications were not more likely to receive adherence messages than adherent patients (p=0.17). DISCUSSION: Targeting HIV prevention efforts to PLHIV is an effective HIV prevention approach to eliminate HIV transmission. Despite intensive training and support, PHDP message delivery remained unacceptably low in rural Mozambique. Patients at high risk for treatment abandonment were not more likely to be counselled about adherence and support measures, something that needs to be addressed. CONCLUSIONS: We need to develop novel strategies to motivate health care providers to deliver these messages more consistently to all patients and develop a system that assists counsellors and clinicians to quickly and effectively determine which messages should be delivered.