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1.
Health Promot Int ; 38(4)2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37611159

RESUMEN

Services offering on-demand delivery of unhealthy commodities, such as fast food, alcohol and smoking/vaping products have proliferated in recent years. It is well known that the built environment can be health promoting or harmful to health, but there has been less consideration of the digital environment. Increased availability and accessibility of these commodities may be associated with increased consumption, with harmful public health implications. Policy regulating the supply of these commodities was developed before the introduction of on-demand services and has not kept pace with the digital environment. This paper reports on semi-structured interviews with health policy experts on the health harms of the uptake in on-demand delivery of food, alcohol and smoking/vaping products, along with their views on policies that might mitigate these harms. We interviewed 14 policy experts from central and local government agencies and ministries, health authorities, non-Government Organisations (NGOs) and university research positions in Aotearoa New Zealand using a purposive sampling strategy. Participants concerns over the health harms from on-demand services encompassed three broad themes-the expansion of access to and availability of unhealthy commodities, the inadequacy of existing restrictions and regulations in the digital environment and the expansion of personalized marketing and promotional platforms for unhealthy commodities. Health policy experts' proposals to mitigate harms included: limiting access and availability, updating regulations and boosting enforcement and limiting promotion and marketing. Collectively, these findings and proposals can inform future research and public health policy decisions to address harms posed by on-demand delivery of unhealthy commodities.


Asunto(s)
Política de Salud , Política Pública , Humanos , Nueva Zelanda , Entorno Construido , Etanol , Comida Rápida
2.
Curr Psychol ; 41(6): 3958-3969, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-32837131

RESUMEN

Despite the widespread popularity of mindfulness meditation for its various benefits, the mechanism underlying the meditation process has rarely been explored. Here, we present two preliminary studies designed to test alternative hypotheses: whether the effect of brief guided mindfulness meditation on empathic concern arises from verbal suggestion (suggestion hypothesis) or as a byproduct of an induced mindfulness state (mindfulness hypothesis). Study 1 was a pilot randomized control trial of sitting (breath-and-body) meditation vs. compassion meditation that provided preliminary support for the mindfulness hypothesis. Study 2 was set up to rule out the possibility that the meditation effects observed in Study 1 were the effects of repeated measures. An inactive control group of participants underwent the repeated measures of empathic concern with no meditation in between. The pre-post comparison demonstrated no significant changes in the measures. Thus, the results of two studies supported the mindfulness hypothesis. Limitations of the present study and future research directions are discussed.

3.
Qual Health Res ; 31(13): 2403-2413, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34384307

RESUMEN

Qualitative health research has been uniquely affected by the COVID-19 pandemic. Various public health directives will likely remain in place until this pandemic is fully controlled, creating long-lasting impacts on the design and conduct of qualitative health research. Virtual qualitative research provides an alternative to traditional interviews or focus groups and can help researchers adhere to public health directives. In this commentary, we respond to methodological needs created by the COVID-19 pandemic. Specifically, we explore unique elements of, and recommendations for, the design and conduct of obtrusive virtual qualitative research (online interviews, online focus groups, and email interviews) and demonstrate crucial ethical, recruitment, analytical, and interpretive considerations. Researchers are currently faced with an ethical imperative to advance virtual qualitative research methods and ensure that rigorous qualitative health research continues during this pandemic and beyond. Our discussions provide a starting point for researchers to explore the potential of virtual qualitative research.


Asunto(s)
COVID-19 , Pandemias , Grupos Focales , Humanos , Investigación Cualitativa , SARS-CoV-2
4.
Drug Alcohol Rev ; 43(2): 416-424, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38044544

RESUMEN

INTRODUCTION: On-demand delivery (<2 h from ordering) of alcohol is relatively new to New Zealand. We aimed to quantify the number of services available and the number of outlets available to purchase from within on-demand services. We then tested whether access differed by neighbourhood demographics. METHODS: We identified six on-demand alcohol services and quantified access to these in Auckland, Wellington and Christchurch. Eighty-one addresses were sampled according to three variables: (i) density of physical alcohol outlet tertile; (ii) socio-economic deprivation tertile; and (iii) areas within the top 20th percentile of Maori within each city. RESULTS: The median number of alcohol outlets to purchase from across all on-demand delivery services was five, though this was higher in Christchurch. For all three cities combined, and for Wellington, the number of outlets available on-demand was highest in areas with the highest density of physical outlets. However, the number of outlets available virtually was not associated with physical outlet density in Auckland or Christchurch. There were no significant differences in access observed for neighbourhood socio-economic deprivation. DISCUSSION AND CONCLUSIONS: On-demand delivery services are changing local alcohol environments, and may be increasing overall access to alcohol at a neighbourhood level. On-demand access patterns do not consistently reflect the physical alcohol environment. The current legislative and policy environment in New Zealand pre-dates the emergence of on-demand alcohol services. Local councils need to consider 'virtual' access as well as physical access when developing Local Alcohol Policies.


Asunto(s)
Bebidas Alcohólicas , Pueblo Maorí , Características de la Residencia , Humanos , Bebidas Alcohólicas/provisión & distribución , Ciudades , Comercio , Nueva Zelanda/epidemiología
5.
SSM Popul Health ; 21: 101349, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36845670

RESUMEN

The increase in availability of online on-demand food and alcohol delivery services has changed the way unhealthy commodities are accessed and understood. We conducted a systematic scoping review of academic and grey literature to map the current knowledge of public health and regulatory/policy outcomes arising from on-demand food and alcohol delivery (defined as delivery within 2 h). We systematically searched three electronic databases and completed supplementary forward citation searches and Google Scholar searches. In total, we screened 761 records (de-duplicated) and synthesised findings from 40 studies by commodity types (on-demand food or alcohol) and outcome focus (outlet, consumer, environmental, labour). Outlet-focused outcomes were most common (n = 16 studies), followed by consumer (n = 11), environmental (n = 7), and labour-focused (n = 6) outcomes. Despite geographical and methodological diversity of studies, results indicate that on-demand delivery services market unhealthy and discretionary foods, with disadvantaged communities having reduced access to healthy commodities. Services that deliver alcohol on-demand can also subvert current alcohol access restrictions, particularly through poor age verification processes. Underpinning these public health impacts is the multi-layered nature of on-demand services and context of the COVID-19 pandemic, which creates ongoing complications as to how populations access food and alcohol. Changing access to unhealthy commodities is an emerging issue in public health. Our scoping review considers priority areas for future research to better inform policy decisions. Current regulation of food and alcohol may not appropriately cover emerging on-demand technologies, necessitating a review of policy.

6.
Artículo en Inglés | MEDLINE | ID: mdl-36554849

RESUMEN

A disconnect between children's ideas and their incorporation into environmental design, in the context of rapid urbanisation and climate crises, compelled us to reflect on children's meaningful participation in positive environmental change. Our research aimed to bring new knowledge to the fore using a participatory, child-centred approach to understanding children's perceptions of health and health-promoting neighbourhoods in Aotearoa New Zealand. The cross-sectional Neighbourhoods and Health study was conducted with 93 primary school-aged children (approximate ages 8 to 10 years) from two schools in Otepoti Dunedin and two schools in Tamaki Makaurau Auckland from June 2020 to August 2021. We present a framework of twelve child-centred topics of importance for health (Healthcare and 'not getting sick', 'How you feel', and Taking care of yourself), health-promoting neighbourhoods (Proximity, safety and feel, Range of 'places to go', 'Friendly streets', and 'No smoking'), and those common to both (Connections with other humans, Healthy food and drink, Exercising and playing sport 'to keep fit', 'Nature' and 'helping the environment', and Recreational activities). The more-than-human theory was used to situate our study findings, and we explored three threads evident in children's thinking: (1) care for humans and non-humans, (2) vital interdependence of human-non-human relations, and (3) understanding complex urban environments through everyday activities. We conclude that the thriving of humans and non-humans in urban environments is important to children in Aotearoa New Zealand. We affirm that children have clear and salient ideas about health and health-promoting neighbourhoods.


Asunto(s)
Ejercicio Físico , Deportes , Humanos , Niño , Estudios Transversales , Nueva Zelanda , Instituciones Académicas
7.
Nutrients ; 14(20)2022 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-36296912

RESUMEN

Access to unhealthy commodities is a key factor determining consumption, and therefore influences the prevalence of non-communicable diseases. Recently, there has been an increase in the availability of food 'on-demand' via meal delivery apps (MDAs). However, the public health and equity impacts of this shift are not yet well understood. This study focused on three MDAs in New Zealand and aimed to answer (1) what is the health profile of the foods being offered on-demand, (2) how many food outlets are available and does this differ by physical access or neighbourhood demographics and (3) does the health profile of foods offered differ by physical access or neighbourhood demographics? A dataset was created by sampling a set of street addresses across a range of demographic variables, and recording the menu items and number of available outlets offered to each address. Machine learning was utilised to evaluate the healthiness of menu items, and we examined if healthiness and the number of available outlets varied by neighbourhood demographics. Over 75% of menu items offered by all MDAs were unhealthy and approximately 30% of all menu items across the three MDAs scored at the lowest level of healthiness. Statistically significant differences by demographics were identified in one of the three MDAs in this study, which suggested that the proportion of unhealthy foods offered was highest in areas with the greatest socioeconomic deprivation and those with a higher proportion of Maori population. Policy and regulatory approaches need to adapt to this novel mode of access to unhealthy foods, to mitigate public health consequences and the effects on population groups already more vulnerable to non-communicable diseases.


Asunto(s)
Enfermedades no Transmisibles , Humanos , Nueva Zelanda , Abastecimiento de Alimentos , Características de la Residencia , Comidas , Comida Rápida
8.
J Exp Bot ; 62(3): 1169-77, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21041369

RESUMEN

Life in extreme environments poses unique challenges to photosynthetic organisms. The ability for an extremophilic green alga and its genetic and mesophilic equivalent to acclimate to changes in their environment was examined to determine the extent of their phenotypic plasticities. The Antarctic extremophile Chlamydomonas raudensis Ettl. UWO 241 (UWO) was isolated from an ice-covered lake in Antarctica, whereas its mesophilic counterpart C. raudensis Ettl. SAG 49.72 (SAG) was isolated from a meadow pool in the Czech Republic. The effects of changes in temperature and salinity on growth, morphology, and photochemistry were examined in the two strains. Differential acclimative responses were observed in UWO which include a wider salinity range for growth, and broader temperature- and salt-induced fluctuations in F(v)/F(m), relative to SAG. Furthermore, the redox state of the photosynthetic electron transport chain, measured as 1-q(P), was modulated in the extremophile whereas this was not observed in the mesophile. Interestingly, it is shown for the first time that SAG is similar to UWO in that it is unable to undergo state transitions. The different natural histories of these two strains exert different evolutionary pressures and, consequently, different abilities for acclimation, an important component of phenotypic plasticity. In contrast to SAG, UWO relied on a redox sensing and signalling system under the growth conditions used in this study. It is proposed that growth and adaptation of UWO under a stressful and extreme environment poises this extremophile for better success under changing environmental conditions.


Asunto(s)
Chlamydomonas/fisiología , Regiones Antárticas , Chlamydomonas/anatomía & histología , Chlamydomonas/crecimiento & desarrollo , Ecosistema , Oxidación-Reducción , Fenotipo , Cloruro de Sodio/metabolismo , Temperatura
9.
BMJ Open ; 11(6): e047368, 2021 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-34155076

RESUMEN

INTRODUCTION: Neighbourhood environments can have significant and enduring impacts on children's physical, psychological and social health. Environments can impact health through promoting or hindering physical activity, active travel, and healthy eating in addition to opportunities for social interaction, cognitive development, rest and relaxation. There is a paucity of research that has examined neighbourhood and health priorities, strengths and needs from the perspectives of the community, and even less that has focused on the perspectives of children within communities. The aim of this article is to describe the research protocol for a project to gather child-identified needs and strengths-based solutions for promoting child health and well-being in urban neighbourhood environments. METHODS AND ANALYSIS: This participatory research project is designed to partner with children in school settings in Tamaki Makaurau Auckland and Otepoti Dunedin, Aotearoa New Zealand. An abundant communities approach will be used with children to identify needs and strengths related to neighbourhoods and health. Specific methods including collaborative, creative, play-based methods such as concept-mapping activities and co-creation of final dissemination material on the key messages are described. Plans for researcher reflections, data analysis and dissemination are also detailed. ETHICS AND DISSEMINATION: This research has been approved by the University of Auckland Human Participants Ethics Committee. Results will be disseminated through child and researcher co-created output, a technical report and academic journal articles. By using evidence-based child-centred approaches to knowledge generation, we anticipate the research will generate new localised insights about children's preferences and needs for healthy neighbourhoods which will be shared with stakeholders in planning and practice. The detailed session protocol including critical researcher reflections is shared in this manuscript for application, development and refinement in future research.


Asunto(s)
Ejercicio Físico , Características de la Residencia , Niño , Estudios Transversales , Humanos , Nueva Zelanda , Percepción
10.
Microbiol Mol Biol Rev ; 70(1): 222-52, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16524924

RESUMEN

Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.


Asunto(s)
Aclimatación , Chlorophyta/fisiología , Frío , Ecosistema , Fotosíntesis , Fitoplancton/fisiología , Chlorophyta/enzimología , Fitoplancton/enzimología
11.
JBI Evid Synth ; 18(7): 1515-1521, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32813390

RESUMEN

OBJECTIVE: This review aims to synthesize existing qualitative studies on the experiences of activity limitations and participation restrictions in individuals with developmental coordination disorder/dyspraxia, their families, and service providers. INTRODUCTION: Developmental coordination disorder features a significant delay in lifespan motor development, which limits daily activities and restricts participation at home, school, workplace, recreation, and in the community. To date, these activity limitations and participation restrictions have been sporadically characterized in quantitative and qualitative studies. However, the nature of the subjective experiences of activity limitations and participation restrictions has not been systematically reviewed or qualitatively synthesized from the first- and third-person perspectives. INCLUSION CRITERIA: The review will consider qualitative studies with participants who are 5 years of age and above, conducted anywhere in the world. We will exclude studies that are not identifiable through English titles or abstracts in English databases, and non-primary peer-reviewed evidence, such as biographies, newspapers, and magazines. METHODS: Key information sources include CINAHL, PsycINFO, MEDLINE, Embase, ERIC, SPORTDiscus, JSTOR, Soc Index, Project Muse, ProQuest Dissertations and Theses, and OpenGrey. No time or language limits will be placed. Two independent reviewers will screen and retrieve potentially relevant studies in full. The full-text of selected studies will be assessed against the inclusion criteria. All included studies will undergo the assessment of methodological quality, data extraction, and the generation of a single comprehensive set of synthesized findings. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42019137616.


Asunto(s)
Apraxias , Trastornos de la Destreza Motora , Atención a la Salud , Humanos , Investigación Cualitativa , Literatura de Revisión como Asunto
12.
Artículo en Inglés | MEDLINE | ID: mdl-33287302

RESUMEN

The school neighbourhood built environment (BE) can facilitate active transport to school (ATS) in adolescents. Most previous studies examining ATS were conducted in large urban centres and focused on BE of home neighbourhoods. This study examined correlations between school-level ATS rates among adolescents, objectively measured school neighbourhood BE features, and adolescents' perceptions of the school route across different urbanisation settings. Adolescents (n = 1260; 15.2 ± 1.4 years; 43.6% male) were recruited from 23 high schools located in large, medium, and small urban areas, and rural settings in Otago, New Zealand. Adolescents completed an online survey. School neighbourhood BE features were analysed using Geographic Information Systems. School neighbourhood intersection density, residential density and walkability index were higher in large urban areas compared to other urbanisation settings. School-level ATS rates (mean 38.1%; range: 27.8%-43.9%) were negatively correlated with school neighbourhood intersection density (r = -0.58), residential density (r = -0.60), and walkability index (r = -0.64; all p < 0.01). School-level ATS rates were also negatively associated with adolescents' perceived safety concerns for walking (r = -0.76) and cycling (r = -0.78) to school, high traffic volume (r = -0.82), and presence of dangerous intersections (r = -0.75; all p < 0.01). Future initiatives to encourage ATS should focus on school neighbourhood BE features and minimise adolescents' traffic safety related concerns.


Asunto(s)
Entorno Construido , Instituciones Académicas , Transportes , Adolescente , Entorno Construido/estadística & datos numéricos , Estudios Transversales , Planificación Ambiental , Femenino , Humanos , Masculino , Nueva Zelanda , Características de la Residencia , Instituciones Académicas/estadística & datos numéricos , Encuestas y Cuestionarios , Transportes/estadística & datos numéricos , Urbanización , Caminata
13.
Artículo en Inglés | MEDLINE | ID: mdl-32218286

RESUMEN

School neighbourhood built environments (SN-BE) can influence adolescents' active transport to school habits. Typically, SN-BE assessment has involved micro-scale (i.e., environmental audits) or macro-scale (Geographic Information Systems (GIS)) assessment tools. However, existing environmental audits are time/resource-intensive and not specific to school neighbourhoods, while GIS databases are not generally purposed to include micro-scale data. This study evaluated the inter-rater reliability and feasibility of using a modified audit tool and protocol (Microscale Audit of Pedestrian Streetscapes Global-School Neighbourhood (MAPS Global-SN)) to assess the SN-BE of twelve secondary schools in Dunedin, New Zealand. Correlations between MAPS Global-SN and GIS measures of the SN-BE were also examined. Specifically, MAPS Global-SN audit and GIS spatial analysis (intersection density, residential density, land use mix, walkability) was conducted within a 0.5 km street-network buffer-zone around all twelve schools. Based on investigator and expert consultation, MAPS Global-SN included eight modifications to both auditing processes and items. Inter-rater reliability data was collected from two independent auditors across two schools. The feasibility of a condensed audit protocol (auditing one side of each street segment in the neighbourhood, compared to both sides) was also assessed. Results indicated the modified MAPS Global-SN tool had good to excellent inter-rater reliability and the condensed MAPS Global-SN audit protocol appeared to sufficiently represent the micro-scale SN-BE. Results also highlighted the complementary nature of micro- and macro-scale assessments. Further recommendations for SN-BE assessment are discussed.


Asunto(s)
Entorno Construido , Planificación Ambiental , Salud Ambiental , Transportes , Adolescente , Entorno Construido/estadística & datos numéricos , Planificación Ambiental/estadística & datos numéricos , Salud Ambiental/métodos , Humanos , Nueva Zelanda , Reproducibilidad de los Resultados , Características de la Residencia , Transportes/estadística & datos numéricos , Caminata
14.
Health Place ; 55: 1-8, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30446347

RESUMEN

Adolescent active transport to school (ATS) is influenced by demographic, social, environmental and policy factors. Yet, the relationship between school neighbourhood built environment (SN-BE) and adolescents' ATS remains largely unexplored. This observational study examined associations between observed, objectively-measured and perceived SN-BE features and adolescents' ATS in Dunedin (New Zealand). Adolescents' perception of safety of walking to school was the strongest correlate of ATS among adolescents living ≤ 2.25 km of school, whereas assessed micro- and macro-scale SN-BE features were not significantly correlated with ATS. Adolescents' perceptions of walking safety should be considered as a part of comprehensive efforts to encourage ATS.


Asunto(s)
Entorno Construido/estadística & datos numéricos , Características de la Residencia , Instituciones Académicas/estadística & datos numéricos , Transportes , Adolescente , Femenino , Sistemas de Información Geográfica , Humanos , Masculino , Nueva Zelanda , Seguridad , Caminata
15.
Methods Mol Biol ; 274: 137-48, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15187276

RESUMEN

Chorophylls and carotenoids are functionally important pigment molecules in photosynthetic organisms. Methods for the determination of chlorophylls a and b, beta-carotene, neoxanthin, and the pigments that are involved in photoprotective cycles such as the xanthophylls are discussed. These cycles involve the reversible de-epoxidation of violaxanthin into antheraxanthin and zeaxanthin, as well as the reversible de-epoxidation of lutein-5,6-epoxide into lutein. This chapter describes pigment extraction procedures from higher plants and green algae. Methods for the determination and quantification using high-performance liquid chromatograpy (HPLC) are described as well as methods for the separation and purification of pigments for use as standards using thin-layer chromatography (TLC). In addition, several spectrophotometric methods for the quantification of chlorophylls a and b are described.


Asunto(s)
Clorofila/análisis , Cromatografía Líquida de Alta Presión/métodos , Cromatografía en Capa Delgada/métodos , Pigmentos Biológicos/análisis , Espectrofotometría/métodos , Arabidopsis/química , Carotenoides/análisis , Carotenoides/aislamiento & purificación , Clorofila/aislamiento & purificación , Estructura Molecular , Pigmentos Biológicos/aislamiento & purificación , Solventes
16.
Biochem Mol Biol Educ ; 32(6): 381-9, 2004 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-21706761

RESUMEN

Freshly isolated, illuminated chloroplasts oxidize water and transfer the resulting electrons through the photosynthetic electron transport chains in their thylakoid membranes to the artificial electron acceptor, dichlorophenol indophenol (DCPIP). As a consequence, DCPIP is reduced and the decline in absorbance over time can be used to measure the rate of electron transfer. When gently heated, chloroplasts lose the capacity to oxidize water and the transfer of electrons to DCPIP is eliminated. Electron transport through chloroplasts to DCPIP is restored in the presence of the artificial electron donor diphenylcarbazide (DPC). If students gain experience with the DCPIP photoreduction assay and are given information on normal chloroplast function, they should be able to predict the behavior of heat-treated chloroplasts in a variety of experimental conditions. A number of such predictions are outlined and tested. The experiments can all be conducted with a limited repertoire of equipment and easily prepared solutions. Consequently, this work is well suited to an investigative study in which each student group, in consultation with instructors, can make and test its own prediction. The ways in which changing different variables can affect the quality of the experimental results is emphasized. Additional studies, on measurements of rates of oxygen evolution and emitted chlorophyll fluorescence, are briefly described to support the inferences that heat-treated chloroplasts do not oxidize water and that the vectorial transfer of electrons through them to DCPIP is identical to that in untreated chloroplasts.

17.
PLoS One ; 9(10): e109289, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25310092

RESUMEN

It is well known that estrogenic compounds affect development of fertilized eggs of many species of birds, fish and amphibians through disrupted activity of carbonic anhydrase (CA). The most potent activity comes from the most commonly occurring synthetic sterol, 17α-Ethynylestradiol (EE2). Less is known about the responses of aquatic phytoplankton to these compounds. Here we show for the first time that, in comparision to the control, the addition of 7 µM EE2 reduced the growth rate of the green alga Chlamydomonas reinhardtii by 68% for cells grown at high CO2. When cells were grown in ambient air (low Ci) with a fully activated carbon concentrating mechanism through the induction of CA activity, the growth rates were reduced by as much as 119%. A reduced growth rate could be observed at EE2 concentrations as low as 10 pM. This was accompanied by a reduced maximum capacity for electron transport in photosystem II as determined by a lower FV/FM for low Ci-grown cells, which indicates the involvement of CAH3, a CA specifically located in the thylakoid lumen involved in proton pumping across the thylakoid membranes. These results were in agreement with an observed reduction in the chloroplastic affinity for Ci as shown by a strong increase in the Michaelis-Menten K0.5 for HCO3-. In itself, a lowering of the growth rate of a green alga by addition of the sterol EE2 warrants further investigation into the potential environmental impact by the release of treated waste water.


Asunto(s)
Chlamydomonas reinhardtii/efectos de los fármacos , Etinilestradiol/farmacología , Fotosíntesis/efectos de los fármacos , Chlamydomonas reinhardtii/crecimiento & desarrollo , Chlamydomonas reinhardtii/metabolismo , Cloroplastos/metabolismo , Transporte de Electrón/efectos de los fármacos , Fotosíntesis/fisiología , Complejo de Proteína del Fotosistema II/metabolismo , Tilacoides/metabolismo
18.
Biochem Cell Biol ; 85(6): 721-9, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18059530

RESUMEN

Using in vivo thermoluminescence, we examined the effects of growth irradiance and growth temperature on charge recombination events in photosystem II reaction centres of the model green alga Chlamydomonas reinhardtii. We report that growth at increasing irradiance at either 29 or 15 degrees C resulted in comparable downward shifts in the temperature peak maxima (T(M)) for S2QB- charge pair recombination events, with minimal changes in S2QA- recombination events. This indicates that such growth conditions decrease the activation energy required for S2QB- charge pair recombination events with no concomitant change in the activation energy for S2QA- recombination events. This resulted in a decrease in the DeltaT(M) between S2QA- and S2QB- recombination events, which was reversible when shifting cells from low to high irradiance and back to low irradiance at 29 degrees C. We interpret these results to indicate that the redox potential of QB was modulated independently of QA, which consequently narrowed the redox potential gap between QA and QB in photosystem II reaction centres. Since a decrease in the DeltaT(M) between S2QA- and S2QB- recombination events correlated with growth at increasing excitation pressure, we conclude that acclimation to growth under high excitation pressure narrows the redox potential gap between QA and QB in photosystem II reaction centres, enhancing the probability for reaction center quenching in C. reinhardtii. We discuss the molecular basis for the modulation of the redox state of QB, and suggest that the potential for reaction center quenching complements antenna quenching via the xanthophyll cycle in the photoprotection of C. reinhardtii from excess light.


Asunto(s)
Chlamydomonas reinhardtii/metabolismo , Complejo de Proteína del Fotosistema II/química , Complejo de Proteína del Fotosistema II/metabolismo , Animales , Chlamydomonas reinhardtii/crecimiento & desarrollo , Chlamydomonas reinhardtii/efectos de la radiación , Luz , Oxidación-Reducción/efectos de la radiación , Presión , Temperatura
19.
Plant Physiol ; 129(3): 1368-81, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12114590

RESUMEN

Cold acclimation and freezing tolerance are the result of complex interaction between low temperature, light, and photosystem II (PSII) excitation pressure. Previous results have shown that expression of the Wcs19 gene is correlated with PSII excitation pressure measured in vivo as the relative reduction state of PSII. Using cDNA library screening and data mining, we have identified three different groups of proteins, late embryogenesis abundant (LEA) 3-L1, LEA3-L2, and LEA3-L3, sharing identities with WCS19. These groups represent a new class of proteins in cereals related to group 3 LEA proteins. They share important characteristics such as a sorting signal that is predicted to target them to either the chloroplast or mitochondria and a C-terminal sequence that may be involved in oligomerization. The results of subcellular fractionation, immunolocalization by electron microscopy and the analyses of target sequences within the Wcs19 gene are consistent with the localization of WCS19 within the chloroplast stroma of wheat (Triticum aestivum) and rye (Secale cereale). Western analysis showed that the accumulation of chloroplastic LEA3-L2 proteins is correlated with the capacity of different wheat and rye cultivars to develop freezing tolerance. Arabidopsis was transformed with the Wcs19 gene and the transgenic plants showed a significant increase in their freezing tolerance. This increase was only evident in cold-acclimated plants. The putative function of this protein in the enhancement of freezing tolerance is discussed.


Asunto(s)
Cloroplastos/genética , Grano Comestible/genética , Proteínas de Plantas/genética , Semillas/genética , Aclimatación/genética , Secuencia de Aminoácidos , Arabidopsis/genética , Cloroplastos/metabolismo , Cloroplastos/ultraestructura , Mapeo Cromosómico , Frío , Grano Comestible/embriología , Grano Comestible/fisiología , Regulación de la Expresión Génica de las Plantas , Hordeum/embriología , Hordeum/genética , Hordeum/fisiología , Inmunohistoquímica , Luz , Microscopía Electrónica , Mitocondrias/genética , Mitocondrias/metabolismo , Datos de Secuencia Molecular , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Complejo de Proteína del Fotosistema II , Hojas de la Planta/ultraestructura , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Conformación Proteica , Secale/embriología , Secale/genética , Secale/fisiología , Semillas/embriología , Semillas/fisiología , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Transducción de Señal , Factores de Tiempo , Triticum/embriología , Triticum/genética , Triticum/fisiología
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