RESUMO
Previous studies of heat tolerance of tropical trees have focused on canopy leaves exposed to full sunlight and high temperatures. However, in lowland tropical forests with leaf area indices of 5-6, the vast majority of leaves experience varying degrees of shade and a reduced heat load compared to sun leaves. Here we tested whether heat tolerance is lower in shade than in sun leaves. For three tropical tree species, Calophyllum inophyllum, Inga spectabilis, and Ormosia macrocalyx, disks of fully developed shade and sun leaves were subjected to 15-min heat treatments, followed by measurement of chlorophyll a fluorescence after 48 h of recovery. In two of the three species, the temperature causing a 50% decrease of the fluorescence ratio Fv/Fm (T50) was significantly lower (by ~ 1.0 °C) in shade than in sun leaves, indicating a moderately decreased heat tolerance of shade leaves. In shade leaves of these two species, the rise in initial fluorescence, F0, also occurred at lower temperatures. In the third species, there was no shade-sun difference in T50. In situ measurements of photosynthetic CO2 assimilation showed that the optimum temperature for photosynthesis tended to be lower in shade leaves, although differences were not significant. At supra-optimal temperatures, photosynthesis was largely constrained by stomatal conductance, and the high-temperature CO2 compensation point, TMax, occurred at considerably lower temperatures than T50. Our study demonstrates that the temperature response of shade leaves of tropical trees differs only marginally from that of sun leaves, both in terms of heat tolerance and photosynthetic performance.
Assuntos
Adaptação Fisiológica , Temperatura Alta , Fotossíntese , Folhas de Planta/fisiologia , Luz Solar , Árvores/fisiologia , Clima Tropical , Adaptação Fisiológica/efeitos da radiação , Dióxido de Carbono/metabolismo , Clorofila A/metabolismo , Fluorescência , Fotossíntese/efeitos da radiação , Folhas de Planta/efeitos da radiação , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiaçãoRESUMO
Heat tolerance of plants exhibiting crassulacean acid metabolism (CAM) was determined by exposing leaf sections to a range of temperatures both in the dark and the light, followed by measuring chlorophyll a fluorescence (Fv/Fm and F0) and assessing visible tissue damage. Three CAM species, Clusia rosea Jacq., Clusia pratensis Seem. and Agave angustifolia Haw., were studied. In acidified tissues sampled at the end of the night and exposed to elevated temperatures in the dark, the temperature that caused a 50% decline of Fv/Fm (T50), was remarkably low (40-43°C in leaves of C. rosea). Conversion of chlorophyll to pheophytin indicated irreversible tissue damage caused by malic acid released from the vacuoles. By contrast, when acidified leaves were illuminated during heat treatments, T50 was up to 50-51°C. In de-acidified samples taken at the end of the light period, T50 reached â¼54°C, irrespective of whether temperature treatments were done in the dark or light. Acclimation of A. angustifolia to elevated daytime temperatures resulted in a rise of T50 from â¼54° to â¼57°C. In the field, high tissue temperatures always occur during sun exposure. Measurements of the heat tolerance of CAM plants that use heat treatments of acidified tissue in the dark do not provide relevant information on heat tolerance in an ecological context. However, in the physiological context, such studies may provide important clues on vacuolar properties during the CAM cycle (i.e. on the temperature relationships of malic acid storage and malic acid release).
RESUMO
There are predictive indexes to identify asthmatic patients from the rest of the recurrent wheezing phenotypes. The aim of this work was to evaluate the association between the positive Asthma Predictive Index (API) and the presence of asthma between the age of six and seven years old, in children from Valdivia, Chile. Methods: API was applied to 101 asthmatic children (cases) and 100 non-asthmatic children (controls). Data were analyzed using STATA v. 11 (2009). Fisher Exact Test was used to determine the relationship between variables. Results: 72.3% of asthmatic patients and 3% of non- asthmatic patients had a positive index. Significant differences (p < 0.001) were shown in all the variables included in the API. In our group of patients, the probability for a child to develop asthma was at least 24 times higher if he/she had a positive API (OR = 84.3 CI95% 24.1-436.5). Conclusion: API is a good tool to predict asthma and allows to take right decisions in recurrent wheezing children younger than 36 months old.
Es un desafío identificar pacientes asmáticos entre sibilantes recurrentes, por eso existen índices predictivos. El objetivo de este estudio es evaluar la asociación entre índice predictivo de asma (IPA) positivo, y presencia de asma entre los seis y siete años de edad, en niños de la comuna de Valdivia. Material y Método: Se aplicó el índice IPA a 101 casos (niños asmáticos) y 100 controles (niños sin asma). Se utilizó STATA v.11 (2009), y Test exacto de Fisher para determinar relación entre variables. Resultados: 72,3% de los pacientes asmáticos y 3% de los no asmáticos tuvieron un índice IPA positivo. Se demostraron diferencias significativas (p < 0,001) en todas las variables que componen los criterios del IPA. En nuestros pacientes, la probabilidad de desarrollar asma fue al menos 24 veces mayor si tenían índice IPA positivo (OR 84,3 IC95% 24,1-436,5). Conclusión: El índice IPA es una buena herramienta para predecir asma, y permite tomar decisiones acertadas en pacientes sibilantes menores de tres años.
Assuntos
Humanos , Criança , Asma/diagnóstico , Sons Respiratórios/etiologia , Valor Preditivo dos Testes , Sistemas de Saúde , Estudos de Casos e Controles , Ficha Clínica , Chile , Inquéritos e Questionários , Dados Estatísticos , Tamanho da AmostraRESUMO
Previous heat tolerance tests of higher plants have been mostly performed with darkened leaves. However, under natural conditions, high leaf temperatures usually occur during periods of high solar radiation. In this study, we demonstrate small but significant increases in the heat tolerance of illuminated leaves. Leaf disks of mature sun leaves from two neotropical tree species, Ficus insipida Willd. and Calophyllum longifolium Willd., were subjected to 15min of heat treatment in the light (500µmol photons m-2s-1) and in the dark. Tissue temperatures were controlled by floating the disks on the surface of a water bath. PSII activity was determined 24h and 48h after heating using chlorophyll a fluorescence. Permanent tissue damage was assessed visually during long-term storage of leaf sections under dim light. In comparison to heat treatments in the dark, the critical temperature (T50) causing a 50% decline of the fluorescence ratio Fv/Fm was increased by ~1°C (from ~52.5°C to ~53.5°C) in the light. Moreover, illumination reduced the decline of Fv/Fm as temperatures approached T50. Visible tissue damage was reduced following heat treatment in the light. Experiments with attached leaves of seedlings exposed to increasing temperatures in a gas exchange cuvette also showed a positive effect of light on heat tolerance.
RESUMO
Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue temperatures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated daytime temperature (39°C), combined with either close to natural (22°C) or elevated (32°C) nighttime temperatures. Under both growth regimes, the critical temperature for irreversible leaf damage, determined by changes in chlorophyll a fluorescence, was approximately 51°C. This is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters.
Assuntos
Aclimatação/fisiologia , Dióxido de Carbono/metabolismo , Ficus/fisiologia , Fotossíntese/fisiologia , Biomassa , Dióxido de Carbono/análise , Respiração Celular , Clorofila/metabolismo , Ficus/crescimento & desenvolvimento , Fluorescência , Temperatura Alta , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/fisiologia , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , ÁrvoresRESUMO
High solar radiation in the tropics is known to cause transient reduction in photosystem II (PSII) efficiency and CO(2) assimilation in sun-exposed leaves, but little is known how these responses affect the actual growth performance of tropical plants. The present study addresses this question. Seedlings of five woody neotropical forest species were cultivated under full sunlight and shaded conditions. In full sunlight, strong photoinhibition of PSII at midday was documented for the late-successional tree species Ormosia macrocalyx and Tetragastris panamensis and the understory/forest gap species, Piper reticulatum. In leaves of O. macrocalyx, PSII inhibition was accompanied by substantial midday depression of net CO(2) assimilation. Leaves of all species had increased pools of violaxanthin-cycle pigments. Other features of photoacclimation, such as increased Chl a/b ratio and contents of lutein, ß-carotene and tocopherol varied. High light caused strong increase of tocopherol in leaves of T. panamensis and another late-successional species, Virola surinamensis. O. macrocalyx had low contents of tocopherol and UV-absorbing substances. Under full sunlight, biomass accumulation was not reduced in seedlings of T. panamensis, P. reticulatum, and V. surinamensis, but O. macrocalyx exhibited substantial growth inhibition. In the highly shade-tolerant understory species Psychotria marginata, full sunlight caused strongly reduced growth of most individuals. However, some plants showed relatively high growth rates under full sun approaching those of seedlings at 40 % ambient irradiance. It is concluded that shade-tolerant tropical tree seedlings can achieve efficient photoacclimation and high growth rates in full sunlight.
Assuntos
Adaptação Fisiológica/efeitos da radiação , Fotossíntese/efeitos da radiação , Plântula/crescimento & desenvolvimento , Plântula/efeitos da radiação , Luz Solar , Árvores/crescimento & desenvolvimento , Árvores/efeitos da radiação , Absorção/efeitos da radiação , Dióxido de Carbono/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Tocoferóis/metabolismo , Clima Tropical , Raios UltravioletaRESUMO
INTRODUCTION: On May 3, 2009, a first case of influenza A/H1N1 infection occurred in the federal state of Saxony-Anhalt, Germany. In order to stop the possible spread of the virus and to study the epidemiological and clinical characteristics of the infection, an investigation was launched by the local health authorities and the RKI. METHODS: Standardised questionnaires were used to assess demographic and clinical data. Specimens were collected from case patients and close contacts and were analysed for influenza A/H1N1 using real-time PCR. RESULTS: The index patient showed fever and coughing 3.5 days after returning from a holiday in Mexico. The local health authorities were informed on May 3, and measures were rapidly implemented. These measures included a trace-back of possible contact persons, isolation of the case and close contacts, prophylactic treatment with Oseltamivir. Virological investigations showed that the case shedded viral genome up until the last day of antiviral therapy. Viral genome was also detected in the spouse and the son of the patient. Both showed no symptoms under a prophylactic treatment with antiviral medication. No viral genome was detected in three other family members, and in six other contact persons outside of the family. DISCUSSION: The spread of the virus was contained due to the fast response of the local health authorities. Two secondary cases occurred in the family. These cases remained asymptomatic, possibly due to antiviral prophylaxis. Epidemiological and virological results suggest that the influenza A/H1N1 virus has a longer incubation period and that viral shedding may probably be prolonged when compared with seasonal influenza.
Assuntos
Surtos de Doenças/prevenção & controle , Saúde da Família , Vírus da Influenza A Subtipo H1N1 , Influenza Humana/epidemiologia , Influenza Humana/transmissão , Medição de Risco/métodos , Viagem/estatística & dados numéricos , Adolescente , Adulto , Análise por Conglomerados , Surtos de Doenças/estatística & dados numéricos , Feminino , Alemanha/epidemiologia , Humanos , Incidência , Influenza Humana/genética , Influenza Humana/virologia , Masculino , México , Pessoa de Meia-Idade , Vigilância da População , Fatores de Risco , Adulto JovemRESUMO
Feces of 70 diarrhoeic and 230 non-diarrhoeic domestic cats from Sao Paulo, Brazil were investigated for enteropathogenic (EPEC), enterohaemorrhagic (EHEC) and enterotoxigenic (ETEC) Escherichia coli types. While ETEC and EHEC strains were not found, 15 EPEC strains were isolated from 14 cats, of which 13 were non-diarrhoeic, and one diarrhoeic. None of 15 EPEC strains carried the bfpA gene or the EPEC adherence factor plasmid, indicating atypical EPEC types. The EPEC strains were heterogeneous with regard to intimin types, such as eae-theta (three strains), eae-kappa (n = 3), eae-alpha1 (n = 2), eae-iota (n = 2), one eae-alpha2, eae-beta1 and eae-eta each, and two were not typeable. The majority of the EPEC isolates adhered to HEp-2 cells in a localized adherence-like pattern and were positive for fluorescence actin staining. The EPEC strains belonged to 12 different serotypes, including O111:H25 and O125:H6, which are known to be pathogens in humans. Multi locus sequence typing revealed a close genetic similarity between the O111:H25 and O125:H6 strains from cats, dogs and humans. Our results show that domestic cats are colonized by EPEC, including serotypes previously described as human pathogens. As these EPEC strains are also isolated from humans, a cycle of mutual infection by EPEC between cats and its households cannot be ruled out, though the transmission dynamics among the reservoirs are not yet understood clearly.
Assuntos
Doenças do Gato/microbiologia , Reservatórios de Doenças/veterinária , Escherichia coli Enteropatogênica/isolamento & purificação , Adesinas Bacterianas/genética , Animais , Brasil , Gatos , Diarreia/microbiologia , Diarreia/veterinária , Escherichia coli Enteropatogênica/genética , Proteínas de Escherichia coli/genética , Fezes/microbiologia , Humanos , FilogeniaRESUMO
Seedlings of two late-successional tropical rainforest tree species, Tetragastris panamensis (Engler) O. Kuntze and Calophyllum longifolium (Willd.), were field grown for 3-4 months at an open site near Panama City (9 degrees N), Panama, under plastic films that either transmitted or excluded most solar UV-B radiation. Experiments were designed to test whether leaves developing under bright sunlight with strongly reduced UV-B are capable of acclimating to near-ambient UV-B conditions. Leaves of T. panamensis that developed under near-ambient UV-B contained higher amounts of UV-absorbing substances than leaves of seedlings grown under reduced UV-B. Photosynthetic pigment composition, content of alpha-tocopherol, CO(2) assimilation, potential photosystem II (PSII) efficiency (evaluated by F(v)/F(m) ratios) and growth of T. panamensis and C. longifolium did not differ between seedlings developed under near-ambient and reduced solar UV-B. When seedlings were transferred from the reduced UV-B treatment to the near-ambient UV-B treatment, a pronounced inhibition of photosynthetic capacity was observed initially in both species. UV-B-mediated inhibition of photosynthetic capacity nearly fully recovered within 1 week of the transfer in C. longifolium, whereas in T. panamensis an about 35% reduced capacity of CO(2) uptake was maintained. A marked increase in UV-absorbing substances was observed in foliage of transferred T. panamensis seedlings. Both species exhibited enhanced mid-day photoinhibition of PSII immediately after being transferred from the reduced UV-B to the near-ambient UV-B treatment. This effect was fully reversible within 1d in T. panamensis and within a few days in C. longifolium. The data show that leaves of these tropical tree seedlings, when developing in full-spectrum sunlight, are effectively protected against high solar UV-B radiation. In contrast, leaves developing under conditions of low UV-B lacked sufficient UV protection. They experienced a decline in photosynthetic competence when suddenly exposed to near-ambient UV-B levels, but exhibited pronounced acclimative responses.
Assuntos
Burseraceae/efeitos da radiação , Clusiaceae/efeitos da radiação , Fotossíntese/efeitos da radiação , Plântula/efeitos da radiação , Árvores/efeitos da radiação , Raios Ultravioleta , Biomassa , Burseraceae/crescimento & desenvolvimento , Dióxido de Carbono/metabolismo , Clusiaceae/crescimento & desenvolvimento , Luz , Complexo de Proteína do Fotossistema II , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/efeitos da radiação , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/efeitos da radiação , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/efeitos da radiação , Plântula/crescimento & desenvolvimento , Fatores de Tempo , Árvores/crescimento & desenvolvimentoRESUMO
Studies with seedlings of tropical rainforest trees ( Calophyllum longifolium Willd.; Tectona grandis L. f.) were designed to test whether high-light stress affects photosynthetic performance and growth. Seedlings were cultivated in pots at a field site in Central Panama (9 degrees N) and separated into two groups: (1) plants exposed to full solar radiation; (2) plants subjected to automatic neutral shading (48 %) whenever visible irradiance surpassed 1000, 1200, or 1600 micromol photons m-2 s-1. After 2-4 months, chlorophyll fluorescence (Fv/Fm ratio), photosynthetic net CO2 uptake, pigment composition, alpha-tocopherol content of leaves, and plant biomass accumulation were measured. Fully sun-exposed, compared to periodically shaded plants, experienced substantial high-light stress around midday, indicated by photoinhibition of photosystem II and depressed net CO2 uptake. Higher contents of xanthophyll cycle pigments, lutein, and alpha-tocopherol showed an enhancement of photoprotection in fully sun-exposed plants. However, in all experiments, the maximum capacity of net CO2 uptake and plant dry mass did not differ significantly between the two treatments. Thus, in these experiments, high-light stress did not impair productivity of the seedlings studied. Obviously, the continuously sun-exposed plants were capable of fully compensating for any potential costs associated with photoinhibition and repair of photosystem II, reduced CO2 assimilation, and processes of high-light acclimation.
Assuntos
Calophyllum/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Luz Solar , Árvores/crescimento & desenvolvimento , Verbenaceae/crescimento & desenvolvimento , Aclimatação , Biomassa , Dióxido de Carbono/metabolismo , Fotossíntese , Complexo de Proteína do Fotossistema II/metabolismo , Complexo de Proteína do Fotossistema II/efeitos da radiação , Temperatura , Clima TropicalRESUMO
Seedlings of neotropical forest trees grown in low light were exposed to 0.5-9 h d-1 direct sunlight, for up to 3 months, to test the capability of mature shade leaves to acclimate to full solar visible and UV radiation. Photosynthetic pigments and the antioxidant, ascorbate, were analysed in leaves of two pioneer and two late-succession species. Seedlings of one or two of these species were used to assess further acclimative responses. Sun-exposure for 0.5 or 1 h d-1 resulted in strongly decreased α-carotene and increased ß-carotene and lutein levels. The pool size of xanthophyll-cycle pigments (sum of viola-, anthera- and zeaxanthin) was increased and their turnover was enhanced. These changes were associated with an increase in the capacity of non-photochemical fluorescence quenching and its 'energy-dependent' component, qE, and with reduced susceptibility to photoinhibition of PSII. Prolonged exposure to full direct sunlight (approximately 4 or 9 h d-1) resulted in a marked decrease of chlorophyll a + b content and increase in chlorophyll a / b ratios and the pool of xanthophyll-cycle pigments (based on chlorophyll), leading to extremely high zeaxanthin levels during high-light periods. Contents of ascorbate and UV-B-absorbing substances were substantially increased. PSI activity exhibited a response to full sunlight that is characteristic of sun leaves. Rates of net photosynthetic CO2 assimilation under saturating light were increased. The data show that mature shade leaves of seedlings of both early- and late-succession tree species can substantially acclimate to full-sunlight conditions by employing similar physiological mechanisms.
Assuntos
Ciguatera , Peixes , Doenças Transmitidas por Alimentos/etiologia , Animais , República Dominicana , Alemanha , Humanos , ViagemRESUMO
Fifty-two patients with American cutaneous leishmaniasis (ACL) from the Pacific coast of Ecuador were treated topically with an ointment containing 15% paramomycin (PR) and 12% methylbenzethonium chloride (MBCL) in vaselinum album (white soft paraffin; white petrolatum). After 20 applications (over 10 or 20 d) all lesions showed complete epithelialization within the first 100 d. Five patients developed new lesions during the one year observation period; 2 of these were probably reinfections. Considering all 5 cases as treatment failures, the healing rates were: 72% after 50 d, 90% after 100 d, and 85% after 360 d. In a separate study in the same area, a group of 23 patients was left without treatment for 3 months. Only 9% of the untreated patients healed spontaneously after 50 d. Growth of the lesion, inflammation and pain were observed at the beginning of treatment. After treatment, most lesions healed rapidly without scars. The drug was well accepted by the patients and was easy to administer under tropical field conditions.