RESUMO
In Arabidopsis thaliana, changes in metabolism and gene expression drive increased drought tolerance and initiate diverse drought avoidance and escape responses. To address regulatory processes that link these responses, we set out to identify genes that govern early responses to drought. To do this, a high-resolution time series transcriptomics data set was produced, coupled with detailed physiological and metabolic analyses of plants subjected to a slow transition from well-watered to drought conditions. A total of 1815 drought-responsive differentially expressed genes were identified. The early changes in gene expression coincided with a drop in carbon assimilation, and only in the late stages with an increase in foliar abscisic acid content. To identify gene regulatory networks (GRNs) mediating the transition between the early and late stages of drought, we used Bayesian network modeling of differentially expressed transcription factor (TF) genes. This approach identified AGAMOUS-LIKE22 (AGL22), as key hub gene in a TF GRN. It has previously been shown that AGL22 is involved in the transition from vegetative state to flowering but here we show that AGL22 expression influences steady state photosynthetic rates and lifetime water use. This suggests that AGL22 uniquely regulates a transcriptional network during drought stress, linking changes in primary metabolism and the initiation of stress responses.
Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Teorema de Bayes , Análise por Conglomerados , Secas , Redes Reguladoras de Genes , Mutação , Fenótipo , Fotossíntese/fisiologia , Estresse Fisiológico , Fatores de Transcrição/genéticaRESUMO
Both photosynthesis (A) and stomatal conductance (gs ) respond to changing irradiance, yet stomatal responses are an order of magnitude slower than photosynthesis, resulting in noncoordination between A and gs in dynamic light environments. Infrared gas exchange analysis was used to examine the temporal responses and coordination of A and gs to a step increase and decrease in light in a range of different species, and the impact on intrinsic water use efficiency was evaluated. The temporal responses revealed a large range of strategies to save water or maximize photosynthesis in the different species used in this study but also displayed an uncoupling of A and gs in most of the species. The shape of the guard cells influenced the rapidity of response and the overall gs values achieved, with different impacts on A and Wi . The rapidity of gs in dumbbell-shaped guard cells could be attributed to size, whilst in elliptical-shaped guard cells features other than anatomy were more important for kinetics. Our findings suggest significant variation in the rapidity of stomatal responses amongst species, providing a novel target for improving photosynthesis and water use.
Assuntos
Luz , Fotossíntese/efeitos da radiação , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Água/fisiologia , Dióxido de Carbono/metabolismo , Cinética , Fótons , Estômatos de Plantas/anatomia & histologia , Especificidade da Espécie , Fatores de TempoRESUMO
In this study of 177 people living with HIV, we examined if spiritual coping leads to slower HIV disease progression (CD4 cells, viral load [VL]), and more positive health behaviors (adherence, safer sex, less substance use). Prior research suggests that physicians' assessment of spiritual coping can be an interventional aid in promoting positive spiritual coping. Longitudinal spiritual coping was rated using qualitative content analysis of six-monthly interviews/essays. Positive spiritual coping (65%) was predominant over negative (7%), whereas 28% did not make significant use of spirituality as a means to cope. Spiritual coping was associated with less substance use disorder but not with less sexual risk behavior. Hierarchical linear modeling demonstrated that spiritual coping predicted sustained undetectable VL and CD4-cell preservation over four years, independent of sociodemographics, baseline disease status, and substance use disorder. Achieving undetectable VL significantly increased over time in participants with positive spiritual coping but decreased among those with negative spiritual coping. For every participant with positive spiritual coping achieving undetectable VL, four with negative spiritual coping reported with detectable/transmittable HIV. Notably, even when controlling for the effect of VL suppression, CD4-cell decline was 2.25 times faster among those engaged in negative versus positive spiritual coping. In conclusion, spiritual coping is associated with positive health behaviors, such as maintaining long-term VL suppression and less onset/relapse of substance use disorder over time. Among those who are sexually active, positive spiritual coping reduces the risk of HIV transmission via VL suppression but may not prevent the transmission of other STDs because spiritual coping is not related to safer sexual behavior. Notably, the association between spiritual coping and immune preservation was direct (i.e., not explained by VL suppression), suggesting potential psychoneuroimmunological pathways. Thus, assessment of spiritual coping may be an important area of intervention to achieve undetectable VL, reduce HIV disease progression, and prevent substance use onset/relapse.
Assuntos
Adaptação Psicológica , Contagem de Linfócito CD4 , Infecções por HIV/psicologia , Espiritualidade , Carga Viral , Adulto , Feminino , Infecções por HIV/imunologia , Infecções por HIV/virologia , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The C3 plant Rhazya stricta is native to arid desert environment zones, where it experiences daily extremes of heat, light intensity (PAR) and high vapour pressure deficit (VPD). We measured the photosynthetic parameters in R. stricta in its native environment to assess the mechanisms that permit it to survive in these extreme conditions. Infrared gas exchange analysis examined diel changes in assimilation (A), stomatal conductance (gs ) and transpiration (E) on mature leaves of R. stricta. A/ci analysis was used to determine the effect of temperature on carboxylation capacity (Vc,max ) and the light- and CO2 -saturated rate of photosynthesis (Amax ). Combined chlorophyll fluorescence and gas exchange light response curve analysis at ambient and low oxygen showed that both carboxylation and oxygenation of Rubisco acted as the major sinks for the end products of electron transport. Physiological analysis in conjunction with gene expression analysis suggested that there are two isoforms of Rubisco activase which may provide an explanation for the ability of R. stricta to maintain Rubisco function at high temperatures. The potential to exploit this ability to cope with extreme temperatures is discussed in the context of future crop improvement.
Assuntos
Apocynaceae/fisiologia , Apocynaceae/efeitos da radiação , Carbono/metabolismo , Clima Desértico , Temperatura Alta , Luz , Fotossíntese/efeitos da radiação , Apocynaceae/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/efeitos da radiação , Filogenia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/metabolismo , Pressão de VaporRESUMO
The extent to which climate change might diminish the efficacy of protected areas is one of the most pressing conservation questions. Many projections suggest that climate-driven species distribution shifts will leave protected areas impoverished and species inadequately protected while other evidence suggests that intact ecosystems within protected areas will be resilient to change. Here, we tackle this problem empirically. We show how recent changes in distribution of 139 Tanzanian savannah bird species are linked to climate change, protected area status and land degradation. We provide the first evidence of climate-driven range shifts for an African bird community. Our results suggest that the continued maintenance of existing protected areas is an appropriate conservation response to the challenge of climate and environmental change.
Assuntos
Distribuição Animal , Aves/fisiologia , Mudança Climática , Conservação dos Recursos Naturais , Animais , Ecossistema , Modelos Biológicos , Tanzânia , Fatores de TempoRESUMO
Heat-stressed crops suffer dehydration, depressed growth, and a consequent decline in water productivity, which is the yield of harvestable product as a function of lifetime water consumption and is a trait associated with plant growth and development. Heat shock transcription factor (HSF) genes have been implicated not only in thermotolerance but also in plant growth and development, and therefore could influence water productivity. Here it is demonstrated that Arabidopsis thaliana plants with increased HSFA1b expression showed increased water productivity and harvest index under water-replete and water-limiting conditions. In non-stressed HSFA1b-overexpressing (HSFA1bOx) plants, 509 genes showed altered expression, and these genes were not over-represented for development-associated genes but were for response to biotic stress. This confirmed an additional role for HSFA1b in maintaining basal disease resistance, which was stress hormone independent but involved H2O2 signalling. Fifty-five of the 509 genes harbour a variant of the heat shock element (HSE) in their promoters, here named HSE1b. Chromatin immunoprecipitation-PCR confirmed binding of HSFA1b to HSE1b in vivo, including in seven transcription factor genes. One of these is MULTIPROTEIN BRIDGING FACTOR1c (MBF1c). Plants overexpressing MBF1c showed enhanced basal resistance but not water productivity, thus partially phenocopying HSFA1bOx plants. A comparison of genes responsive to HSFA1b and MBF1c overexpression revealed a common group, none of which harbours a HSE1b motif. From this example, it is suggested that HSFA1b directly regulates 55 HSE1b-containing genes, which control the remaining 454 genes, collectively accounting for the stress defence and developmental phenotypes of HSFA1bOx.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Ligação a DNA/metabolismo , Secas , Fatores de Transcrição/metabolismo , Água/metabolismo , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Resistência à Doença/genética , Fatores de Transcrição de Choque Térmico , Temperatura Alta , Pseudomonas syringae/patogenicidade , Fatores de Transcrição/genéticaRESUMO
The use of chlorophyll fluorescence to monitor photosynthetic performance in algae and plants is now widespread. This review examines how fluorescence parameters can be used to evaluate changes in photosystem II (PSII) photochemistry, linear electron flux, and CO(2) assimilation in vivo, and outlines the theoretical bases for the use of specific fluorescence parameters. Although fluorescence parameters can be measured easily, many potential problems may arise when they are applied to predict changes in photosynthetic performance. In particular, consideration is given to problems associated with accurate estimation of the PSII operating efficiency measured by fluorescence and its relationship with the rates of linear electron flux and CO(2) assimilation. The roles of photochemical and nonphotochemical quenching in the determination of changes in PSII operating efficiency are examined. Finally, applications of fluorescence imaging to studies of photosynthetic heterogeneity and the rapid screening of large numbers of plants for perturbations in photosynthesis and associated metabolism are considered.
Assuntos
Clorofila , Fotossíntese/fisiologia , Plantas/metabolismo , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Clorofila/química , Clorofila/fisiologia , Transporte de Elétrons , Corantes Fluorescentes , Luz , Complexo de Proteína do Fotossistema I , Complexo de Proteína do Fotossistema II , Fenômenos Fisiológicos VegetaisRESUMO
Social pair housing of calves has previously demonstrated positive impacts for calves, so this study aimed to compare the health and behaviour of calves kept in individual compared to pair housing on a single commercial UK dairy farm. A total of 457 Holstein and Jersey heifer calves were recruited and systematically allocated to individual and pair housing. Weekly visits were conducted up to 8 weeks of age, with weight and presence of clinical disease measured using both a standardized scoring system and thoracic ultrasonography. A subset of calves (n = 90) had accelerometers attached to monitor activity, with CCTV placed above a further 16 pens to allow behavioural assessments to be made via continuous focal sampling at 1 and 5 weeks of age. During the study, there was a mortality rate of 2.8%, and an average daily liveweight gain (ADLG) of 0.72 kg/day, with no significant effect of housing group (p = 0.76). However, individually housed calves had increased odds of developing disease (OR = 1.88, p = 0.014). Accelerometer data showed that housing group had no effect on lying times, with a mean of 18 h 11 min per day (SD 39 min) spent lying down. The motion index was significantly higher in pair-housed calves (F1,83 = 440.3, p < 0.01), potentially due to more social play behaviour. The total time engaged in non-nutritive oral behaviours (NNOBs) was not impacted by housing group (p = 0.72). Pair-housed calves split their time conducting NNOBs equally between inanimate objects and on their pen mates' body. Individually housed calves spent significantly more time with their head out of the front of the pen (p = 0.006), and also engaged in more self-grooming than pair-housed calves (p = 0.017), possibly due to a lack of socialization. The overall findings of this study indicate that within a UK commercial dairy management system, pair-housed calves were healthier and more active than individually housed calves, while housing group did not influence ADLG or the occurrence of NNOBs.
RESUMO
Electron flux from water via photosystem II (PSII) and PSI to oxygen (water-water cycle) may provide a mechanism for dissipation of excess excitation energy in leaves when CO(2) assimilation is restricted. Mass spectrometry was used to measure O(2) uptake and evolution together with CO(2) uptake in leaves of French bean and maize at CO(2) concentrations saturating for photosynthesis and the CO(2) compensation point. In French bean at high CO(2) and low O(2) concentrations no significant water-water cycle activity was observed. At the CO(2) compensation point and 3% O(2) a low rate of water-water cycle activity was observed, which accounted for 30% of the linear electron flux from water. In maize leaves negligible water-water cycle activity was detected at the compensation point. During induction of photosynthesis in maize linear electron flux was considerably greater than CO(2) assimilation, but no significant water-water cycle activity was detected. Miscanthus × giganteus grown at chilling temperature also exhibited rates of linear electron transport considerably in excess of CO(2) assimilation; however, no significant water-water cycle activity was detected. Clearly the water-water cycle can operate in leaves under some conditions, but it does not act as a major sink for excess excitation energy when CO(2) assimilation is restricted.
Assuntos
Dióxido de Carbono/metabolismo , Fotossíntese , Folhas de Planta/fisiologia , Água/fisiologia , Clorofila/análise , Transporte de Elétrons , Espectrometria de Massas , Oxigênio/metabolismo , Phaseolus/metabolismo , Poaceae/metabolismo , Superóxidos/análise , Zea mays/metabolismoRESUMO
Foot complications cause substantial morbidity in Tanzania, where 70% of leg amputations occur in diabetic patients. The Step by Step Foot Project was initiated to train healthcare personnel in diabetic foot management, facilitate transfer of knowledge and expertise, and improve patient education. The project comprised a 3-day basic course with an interim period 1-year of for screening, followed by an advanced course and evaluation of activities. Fifteen centres from across Tanzania participated during 2004-2006 and 12 during 2004-2007. Of 11,714 patients screened in 2005, 4335 (37%) had high-risk feet. Of 461 (11%) with ulcers, 45 (9·8%) underwent major amputation. Of 3860 patients screened during 2006-2007, there was a significant increase in the proportion with ulcers and amputations compared with 2005 (P < 0·001), likely a result of enhanced case finding. During 2005-2008, there was a fall in the incidence of foot ulcers in patient referrals to the main tertiary care centre in Dar es Salaam and a parallel fall in amputation among these referrals. In conclusion, the Step by Step Foot Project in Tanzania improved foot ulcer management for persons with diabetes and resulted in permanent, operational foot clinics across the country. This programme is an effective model for improving outcomes in other less-developed countries.
Assuntos
Países em Desenvolvimento , Pé Diabético/prevenção & controle , Programas de Rastreamento , Educação de Pacientes como Assunto , Desenvolvimento de Programas/métodos , Pé Diabético/epidemiologia , Humanos , Incidência , Estudos Retrospectivos , Tanzânia/epidemiologia , Resultado do TratamentoRESUMO
Communication failures in healthcare constitute a major root cause of adverse events and medical errors. Considerable evidence links failures to raise concerns about patient harm in a timely manner with errors in medication administration, hygiene and isolation, treatment decisions, or invasive procedures. Expressing one's concern while navigating the power hierarchy requires formal training that targets both the speaker's emotional and verbal skills and the receiver's listening skills. We conducted a scoping review to examine the scope and components of training programs that targeted healthcare professionals' speaking-up skills. Out of 9,627 screened studies, 14 studies published between 2005 and 2018 met the inclusion criteria. The majority of the existing training exclusively relied on one-time training, mostly in simulation settings, involving subjects from the same profession. In addition, most studies implicitly referred to positional power as defined by titles; few addressed other forms of power such as personal resources (e.g., expertise, information). Almost none addressed the emotional and psychological dimensions of speaking up. The existing literature provides limited evidence identifying effective training components that positively affect speaking-up behaviors and attitudes. Future opportunities include examining the role of healthcare professionals' conflict engagement style or leaders' behaviors as factors that promote speaking-up behaviors.
Assuntos
Comunicação , Atenção à Saúde/normas , Pessoal de Saúde/educação , Pessoal de Saúde/psicologia , Erros Médicos/prevenção & controle , Segurança do Paciente/normas , Guias de Prática Clínica como Assunto , Adulto , Currículo , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: This project engaged teams from Federally Qualified Health Centers (FQHCs) in a quality improvement (QI) collaborative to improve clinical flow (increase quality and efficiency of operations), using a novel combination of Breakthrough Series Collaborative tools with Project ECHO's telementoring model. This mixed methods study describes the collaborative and evaluates its success in generating improvement and developing QI capacity at participating FQHCs. METHODS: The 18-month collaborative used three in-person/virtual learning session workshops and weekly telementoring sessions with brief lectures and case-based learning. Participants engaged in QI work (for example, PDSAs [Plan-Do-Study-Act]) and tracked data for 10 care system measures to evaluate progress. These data were averaged across consistently reporting sites for standard run chart analysis. Semistructured interviews assessed the effectiveness and value of the approach for participants. RESULTS: Fifteen sites across the United States participated for one year (Cohort 1); 10 sites continued to 18 months (Cohort 2). Cohort 2 evidenced improvement for 6 measures: Patient/Family Experience, Patient Time Valued, Empanelment, Cycle Time, Colorectal Cancer Screening Rate, and Third Next Available Appointment. Progress varied across sites and measures. Participant interviews indicated value from both in-person and virtual activities, increased QI knowledge, and professional growth, as well as challenges when participants lacked time, engagement, leadership support, and consistent and committed staff. CONCLUSION: This novel collaborative structure is promising. Evidence indicates progress in building QI capacity and improving processes and patient experience across participating FQHCs. Future iterations should address barriers to improvement identified here. Additional work is needed to compare the efficacy of this approach to other collaborative modes.
Assuntos
Práticas Interdisciplinares , Melhoria de Qualidade , Detecção Precoce de Câncer , Humanos , Liderança , Estados UnidosRESUMO
Reactive oxygen species (ROS) are involved in many signalling pathways and numerous stress responses in plants. Consequently, it is important to be able to identify and localize ROS in vivo to evaluate their roles in signalling. A number of probes that have a high affinity for specific ROS and that are effectively taken up by cells and tissues are commercially available. Applications to intact leaves of singlet oxygen sensor green (SOSG), nitroblue tetrazolium (NBT), di-amino benzidine (DAB) and Amplex Red to detect singlet oxygen, superoxide and hydrogen peroxide are described. Imaging of the probes in the cells and tissues of leaves allows sites of ROS production to be identified.
Assuntos
Folhas de Planta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Peróxido de Hidrogênio/metabolismo , Folhas de Planta/citologia , Oxigênio Singlete/metabolismo , Superóxidos/metabolismoRESUMO
The Institute for Healthcare Improvement has long supported the use of balanced measures to assess improvement among patients at both the individual and the population levels. Although biomedical outcomes and process measures have been widely accepted, patient-reported measures are still not in widespread use. The most common use of such measures is at the population level to gauge satisfaction with care long after it has been provided. This article examines barriers and solutions to including patient-reported measures at the point of care.
Assuntos
Benchmarking/métodos , Participação do Paciente , Assistência Centrada no Paciente/normas , Pesquisas sobre Atenção à Saúde , Qualidade da Assistência à SaúdeRESUMO
Multiple reports have concluded that healthcare does not reliably meet patient needs and can even cause harm. The Institute for Healthcare Improvement (IHI) has adapted reliability principles and methods from other industries and applied them in healthcare with promising results in hospital settings. This article describes how one outpatient system successfully applied the IHI reliability methods to multiple clinical and administrative processes. How the application may differ in outpatient environments is also discussed. In particular, the patient role is much more central, and a strong collaborative engagement with the patient is likely necessary to achieve high reliability. Applying reliability principles to patient-centered processes is a critical and undeveloped area.
Assuntos
Assistência Centrada no Paciente/normas , Garantia da Qualidade dos Cuidados de Saúde/métodos , Instituições de Assistência Ambulatorial/organização & administração , Humanos , Estudos de Casos Organizacionais , Objetivos Organizacionais , Assistência Centrada no Paciente/organização & administração , South CarolinaRESUMO
Patients, not healthcare providers, are the primary managers of their health conditions. Current healthcare falls short of providing the kind of support that patients need to optimally manage their conditions. But there are simple and effective self-management support tools and methods that are easy to learn and can be used within the time constraints of the office visit. In addition to tools and methods, supporting self-management requires practice redesign to reliably deliver optimal care to all patients. Whether the care team consists of a solo physician or a large, multiphysician organization, applying basic principles and using simple tools can enable patients to take a more active role in improving their health.
Assuntos
Participação do Paciente , Autocuidado , Instituições de Assistência Ambulatorial , Humanos , Assistência Centrada no Paciente/métodosRESUMO
Transgenic antisense tobacco plants with a range of reductions in sedoheptulose-1,7-bisphosphatase (SBPase) activity were used to investigate the role of photosynthesis in stomatal opening responses. High resolution chlorophyll a fluorescence imaging showed that the quantum efficiency of photosystem II electron transport (F(q)(')/F(m)(')) was decreased similarly in both guard and mesophyll cells of the SBPase antisense plants compared to the wild-type plants. This demonstrated for the first time that photosynthetic operating efficiency in the guard cells responds to changes in the regeneration capacity of the Calvin cycle. The rate of stomatal opening in response to a 30 min, 10-fold step increase in red photon flux density in the leaves from the SBPase antisense plants was significantly greater than wild-type plants. Final stomatal conductance under red and mixed blue/red irradiance was greater in the antisense plants than in the wild-type control plants despite lower CO(2) assimilation rates and higher internal CO(2) concentrations. Increasing CO(2) concentration resulted in a similar stomatal closing response in wild-type and antisense plants when measured in red light. However, in the antisense plants with small reductions in SBPase activity greater stomatal conductances were observed at all C(i) levels. Together, these data suggest that the primary light-induced opening or CO(2)-dependent closing response of stomata is not dependent upon guard or mesophyll cell photosynthetic capacity, but that photosynthetic electron transport, or its end-products, regulate the control of stomatal responses to light and CO(2).
Assuntos
Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Nicotiana/fisiologia , Nicotiana/efeitos da radiação , Fotossíntese , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Luz , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo , Fotossíntese/efeitos da radiação , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estômatos de Plantas/enzimologia , Estômatos de Plantas/genética , Nicotiana/enzimologia , Nicotiana/genéticaRESUMO
Oxygen is both product and substrate of photosynthesis and metabolism in plants, by oxygen evolution through water splitting and uptake by photorespiration and respiration. It is important to investigate these processes simultaneously in leaves, especially in response to environmental variables, such as light and temperature. To distinguish between processes that evolve or take up O2 in leaves in the light, in vivo gas exchange of stable isotopes of oxygen and membrane inlet mass spectrometry is used. A closed-cuvette system for gas exchange of leaf disks is described, using the stable isotopes 16O2 and 18O2, with a semipermeable membrane gas inlet and isotope mass separation and detection by mass spectrometry. Measurement of evolution and uptake, as well as CO2 uptake, at a range of light levels allows composition of a light-response curve, here described for French bean and maize leaf disks.
Assuntos
Marcação por Isótopo , Espectrometria de Massas , Oxigênio/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Análise de Dados , Luz , Espectrometria de Massas/métodosRESUMO
Plastids are vital plant organelles involved in many essential biological processes. Plastids are not created de novo but divide by binary fission mediated by nuclear-encoded proteins of both prokaryotic and eukaryotic origin. Although several plastid division proteins have been identified in plants, limited information exists regarding possible division control mechanisms. Here, we describe the identification of GIANT CHLOROPLAST 1 (GC1), a new nuclear-encoded protein essential for correct plastid division in Arabidopsis. GC1 is plastid-localized and is anchored to the stromal surface of the chloroplast inner envelope by a C-terminal amphipathic helix. In Arabidopsis, GC1 deficiency results in mesophyll cells harbouring one to two giant chloroplasts, whilst GC1 overexpression has no effect on division. GC1 can form homodimers but does not show any interaction with the Arabidopsis plastid division proteins AtFtsZ1-1, AtFtsZ2-1, AtMinD1, or AtMinE1. Analysis reveals that GC1-deficient giant chloroplasts contain densely packed wild-type-like thylakoid membranes and that GC1-deficient leaves exhibit lower rates of CO(2) assimilation compared to wild-type. Although GC1 shows similarity to a putative cyanobacterial SulA cell division inhibitor, our findings suggest that GC1 does not act as a plastid division inhibitor but, rather, as a positive factor at an early stage of the division process.