Resumen Introducción. La enfermedad de Erdheim Chester es un trastorno infrecuente, de etiología no clara y edad de presentación variable, que se caracteriza por la proliferación anormal de histiocitos no Langerhans. Puede presentarse de forma asintomática, con manifestaciones locales o como complicaciones sistémicas. El diagnóstico se basa en las condiciones clínicas del paciente, estudios imagenológicos y el estudio anatomopatológico, mediante el cual se confirma la enfermedad. Caso clínico. Paciente masculino con una lesión lítica en el séptimo arco costal, inicialmente asintomático y posteriormente con dolor torácico persistente. Se realizó resección y reconstrucción de la pared torácica, con resolución de la sintomatología y adecuada evolución posoperatoria. El resultado de la patología confirmó el diagnóstico de enfermedad de Erdheim Chester. Discusión. Se presenta el caso de un paciente con compromiso costal y fractura patológica como localización y manifestación inusual de la enfermedad de Erdheim Chester, tratado quirúrgicamente de forma adecuada, y sin aparición de recidiva. Debido a la diversidad de síntomas que pueden presentar y a la afectación de múltiples órganos, además de los estudios imagenológicos, la clínica debe orientar los exámenes complementarios, como electro o ecocardiograma, resonancia nuclear magnética, o angioTAC. En los pacientes asintomáticos se ha recomendado un manejo expectante y en los sintomáticos el tratamiento médico con glucocorticoides, inhibidores de BRAF e interferón alfa. El papel de la cirugía no ha sido estudiado a profundidad.

Abstract Introduction. Erdheim Chester disease is a rare disorder of unclear etiology and variable age of presentation, characterized by abnormal proliferation of non-Langerhans histiocytes. It can present asymptomatic, with local manifestations or as systemic complications. The diagnosis is based on the clinical conditions of the patient, imaging studies, and the pathological study, through which the disease is confirmed. Clinical case. A male patient with a lytic lesion in the seventh costal arch, initially asymptomatic and later with persistent chest pain, underwent resection and reconstruction of the chest wall, with resolution of the symptoms and adequate postoperative evolution. The pathology report confirmed the diagnosis of Erdheim Chester’s disease. Discussion. The case of a patient with rib involvement and pathological fracture is presented as an unusual location and manifestation of Erdheim Chester’s disease, treated surgically appropriately, and without recurrence. Due to the diversity of symptoms that they can present and the involvement of multiple organs, in addition to imaging studies, the clinic should direct complementary tests such as electrocardiogram or echocardiogram, magnetic resonance imaging, or CT angiography. Expectant management has been recommended in asymptomatic patients, and medical treatment with glucocorticoids, BRAF inhibitors, and interferon alfa in symptomatic patients. The role of surgery has not been studied in depth.

Resumen La agenesia esternal es una rara malformación del desarrollo embrionario del esternón, que puede estar o no relacionado con otras anomalías congénitas. Se presenta el caso de un paciente de 4 años de edad con agenesia esternal total, que fue llevado a reconstrucción de la pared torácica anterior con material protésico absorbible y pericardio bovino, logrando la adecuada estabilidad de la pared torácica y la corrección de la función de la misma, con una evolución satisfactoria después de dos años de seguimiento.

Abstract Sternal cleft is a rare malformation of the embryonic development of the sternum, which may or may not be related to other congenital anomalies. We present the case of a 4-year-old patient with total sternal cleft, who underwent reconstruction of the anterior chest wall with absorbable prosthetic material and bovine pericardium, achieving adequate stability and correction of the function of the chest wall, with a satisfactory evolution after two years of follow-up.

Resumen Introducción. El manejo quirúrgico de las lesiones de la pared costal con resección y reconstrucción con material protésico ha venido en aumento, debido al avance en las técnicas quirúrgicas y en la experiencia del cirujano, así como en la innovación y las características de los materiales protésicos, que permiten realizar resecciones amplias de la pared garantizando una mayor estabilidad esquelética, una menor alteración de la mecánica respiratoria y mejores los resultados estéticos. Métodos. Se presenta la experiencia en la clínica CardioVID, Medellín, Colombia, entre los años 2015 y 2019, mediante una revisión retrospectiva de 8 casos sometidos a resección de lesiones benignas de la pared torácica y reconstrucción con material protésico. Resultados. Se encontró una adecuada evolución de los pacientes, con un buen resultado estético y funcional, con adecuado control de la enfermedad, sin reportes de complicaciones ni de recidiva en el seguimiento. Discusión. Una técnica adecuada permite la reconstrucción de estos defectos con complicaciones mínimas y bajas tasas de extracción de prótesis, finalizando con excelentes resultados funcionales y cosméticos. Con nuestra experiencia podemos concluir que la elección adecuada de los pacientes candidatos a manejo quirúrgico, una buena técnica quirúrgica y un personal con experiencia son cruciales para lograr buenos resultados en cuanto a función pulmonar y estética. Además de lograr una sobrevida bajo los parámetros establecidos posterior a lograr una resección R0.

Abstract Introduction. Surgical management of chest wall lesions with resection and reconstruction with prosthetic material has been increasing, due to advances in surgical techniques and surgeon’s experience, as well as innovation and characteristics of prosthetic materials. They allow wide resections of the wall, guaranteeing greater skeletal stability, less alteration of respiratory mechanics, and better aesthetic results. Methods. The experience in the CardioVID clinic, Medellín, Colombia, between the years 2015 and 2019, is presented through a retrospective review of eight cases that underwent resection of benign lesions of the chest wall and reconstruction with prosthetic material. Results. An adequate evolution of the patients was found, with a good aesthetic and functional result, with adequate control of the disease, without reports of complications or recurrence in follow-up. Discussion. An adequate technique allows the reconstruction of these defects with minimal complications and low prosthesis extraction rates, ending with excellent functional and cosmetic results. With our experience, we can conclude that the proper choice of patients who are good candidates for surgical management, a good surgical technique, and an experienced staff are crucial to achieve good results in terms of lung function and aesthetics results, in addition to obtain survival under the established parameters after achieving an R0 resection.

Resumen Los derrames de petróleo y sus derivados producen fuertes impactos en el equilibrio de los ecosistemas, ya que no sólo arrasan con su biodiversidad, sino que dejan graves consecuencias que dificultan su capacidad de recuperación. Se ha reportado que microorganismos de zonas contaminadas con hidrocarburos desarrollan habilidades para la degradación de estos contaminantes. Con el propósito de determinar la capacidad de microorganismos nativos de suelo contaminado con petróleo para degradar el queroseno, se seleccionaron dos cepas de microorganismos previamente aisladas de un suelo expuesto a derivados del petróleo, que mostraron tolerancia al contaminante, mediante pruebas de concentración mínima inhibitoria (CMI). La remoción de hidrocarburos alifáticos saturados (n-alcanos C-10 a C-16) se realizaron con las cepas seleccionadas e identificadas como Candida metapsilosis SH1 y Burkholderia cepacia SH3, que presentaron tolerancia a concentraciones superiores al 10% de queroseno. La concentración de hidrocarburos se determinó utilizando un cromatógrafo de gases-masas (GCMS) y los resultados se analizaron comparando las abundancias relativas. Los microorganismos demostraron la capacidad de biodegradación selectiva de los hidrocarburos de cadena larga, causando el fraccionamiento, correlacionado con el aumento de los hidrocarburos de cadena corta (C10 a C12). Estos resultados evidencian aplicaciones promisorias de los microorganismos analizados para mitigar la contaminación de sitios afectados por queroseno. y derivados del petróleo.

Abstract The oil spills and their derivatives produce strong impacts on ecosystems balance, as they not only destroy their biodiversity, but also leave serious consequences that hinder their resilience. On the last decades, microbiology studies have shown evidences that microorganisms from polluted areas develop abilities to break pollutants. The purpose was to determine the ability of wild microorganisms from oil contaminated soil to biodegrade kerosene, two microorganisms strains was previously isolated from exposed to petroleum derivatives soil, which showed contaminant tolerance, was selected by means of minimum inhibitory concentration (MIC). The removal of saturated aliphatic hydrocarbons (n-alkanes of C-10 to C-16) were carried out with the strains selected and identified as Candida metapsilosis SH1 and Burkholderia cepacia SH3, which presented tolerance to concentrations greater than 10% of kerosene. The concentration of hydrocarbons was determined using a gas-mass chromatograph (GCMS) and the results were analyzed by comparing relative abundances. The microorganisms demonstrated the capacity for selective biodegradation of long chain hydrocarbons, causing fractionation correlated with the increase of short chain hydrocarbons (C10 to C12). These results show promising applications of the microorganisms tested to mitigate the contamination of sites affected by kerose and oil derivatives.

Resumen El secuestro pulmonar es una enfermedad congénita infrecuente caracterizada por la presencia de una porción de parénquima pulmonar que recibe vascularización independiente de la circulación sistémica. Se presentan tres casos de secuestro pulmonar intralobares, de presentación tardía, uno de ellos asociado a una malformación adenomatosa quística y en los cuales el manejo se completó por videotoracoscopia: dos de ellos con lobectomía total y uno con lobectomía sublobar. Se trata de una enfermedad de presentación clínica variable y cuyo tratamiento es, en la mayoría de los casos, quirúrgico, requiriéndose usualmente resecciones lobares, las cuales pueden llevarse a cabo de manera eficaz y segura por videotoracoscopia.

Abstract Pulmonary sequestration is an infrequent congenital disease characterized by the presence of a portion of pulmonary parenchyma that receives vascularization independent of the systemic circulation. We present three cases of intralobar pulmonary sequestration of late presentation, one of them associated with a cystic adenomatous malformation and in which the management was completed by videothoracoscopy: two of them with total lobectomy and the other with sublobar lobectomy. It is a disease of variable clinical presentation and whose treatment is, in most cases, surgical, usually requiring lobar resections, which can be carried out effectively and safely by video-assisted thoracoscopy.

ABSTRACT Objectives: To evaluate the diagnostic performance of preoperative multiparametric magnetic resonance imaging (mp-MRI) as a predictor of extracapsular extension (ECE) and unfavorable Gleason score (GS) in patients with intermediate and high-risk prostate cancer (PCa). Materials and Methods: Patients with clinically localized PCa who underwent radical prostatectomy (RP) and had preoperative mp-MRI between May-2011 and December-2013. Mp-MRI was evaluated according to the European Society of Urogenital Radiology MRI prostate guidelines by two different readers. Histopathological RP results were the standard reference. Results: 79 patients were included; mean age was 61 and median preoperative prostate-specific antigen (PSA) 7.0. On MRI, 28% patients had ECE evidenced in the mp-MRI, 5% seminal vesicle invasion (SVI) and 4% lymph node involvement (LNI). At RP, 39.2% had ECE, 26.6% SVI and 12.8% LNI. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of mp-MRI for ECE were 54.9%, 90.9%, 76%, 81% and 74.1% respectively; for SVI values were 19.1%, 100%, 77.3%, 100% and 76.1% respectively and for LNI 20%, 98.4%, 86.7%, 66.7% and 88.7%. Conclusions: Major surgical decisions are made with digital rectal exam (DRE) and ultrasound studies before the use of Mp-MRI. This imaging study contributes to rule out gross extraprostatic extension (ECE, SVI, LNI) without competing with pathological studies. The specificity and NPV are reasonable to decide surgical approach. A highly experienced radiology team is needed to provide accurate estimations of tumor extension and aggressiveness.

Objetivo: Determinar la prevalencia de la toma de citología vaginal en las estudiantes de los seis primeros semestres de los programas profesionales de la Facultad de Salud de una universidad pública en Cali (Colombia) durante 2007. Materiales y métodos: Estudio descriptivo transversal con estudiantes de los seis primeros semestres de programas en la Facultad de Salud de una universidad pública en Cali a través de una encuesta en la que se determinó la toma de citología vaginal y comportamientos de salud sexual y reproductiva. Resultados: Participaron 180 estudiantes con un promedio de edad de 19,9±2,5 años. 41,7% de las encuestadas se habían realizado citología vaginal; de éstas, el 23,3% se la realizaban cada año. El 84% de las participantes habían reclamado el resultado. El 35,3% habían tenido un compañero sexual, y la edad promedio de inicio de relaciones sexuales fue 16,8±1,5 años. El principal argumento para no realizársela fue la condición de virginidad (40%). Se encontró asociación estadística entre la toma de citología vaginal con edad (p=0,002), el estar casada (p=0,002), el número de relaciones sexuales en el último mes (p<0.0001), el uso de métodos de planificación hormonal (p<0,0001) o el no uso de dichos métodos (p<0,0001). Conclusiones: La prevalencia de toma de citología vaginal en las estudiantes de los seis primeros semestres de los programas académicos de salud de una universidad pública en Cali es menor que la descrita en la población general según la Encuesta Nacional de Demografía y Salud 2005.

Objective: Determine the prevalence of taking Pap Smear in the students of the first six semesters of the professional programs of the faculty of Health of a public University of Cali en 2007. Materials and methods: It was carried out a cross sectional study with students of professional programs in the faculty of health of a public university in Cali, Colombia through an inquiry that included information about achieve Pap smear and sexuality behaviors. Results: 180 students participated and the age average was 19,9±2,5 años. 41,7% of students carried out Pap smear; 23,3% each year. 84% of students claimed the result. 35,5% have have one sexual partner and age average for initial intercourse was 16,8±1,5 years. The main reason for not take Pap smear was virginity(40%). There are statistic association between take Pap smear with age (p=0,002), married status (p=0,002), number of sexual intercourses in last month (p<0,0001), use of hormonal anticonceptives (p<0,0001) or not use of anticonceptive (p<0,0001) Conclusion: The prevalence of realization of Pap smear in student of six semesters of professional programs of faculty of Health in public university of Cali, Colombia is less than prevalence of general population described by Demography and Health National Survey 2005.

O crescimento e a distribuição do sistema radicular afetam as respostas das plantas à ocorrência de deficiência hídrica. Este trabalho teve como objetivo avaliar em mudas de laranjeira 'Valência' enxertada sobre limoeiro 'Cravo' ou Poncirus trifoliata ('Trifoliata') o crescimento de raízes, as trocas gasosas (CO2 e H2O), o potencial da água na folha e a distribuição de carboidratos nos diversos órgãos, em plantas submetidas à deficiência hídrica. As mudas foram transplantadas para 32 rizotrons, que permitiam a visualização das raízes, sendo 16 para cada porta-enxerto e submetidas ou não à irrigação. A deficiência hídrica às plantas foi aplicada pela interrupção do fornecimento de água às plantas. A condutância estomática decaiu após o quarto dia sem irrigação, causando redução da fotossíntese, da transpiração e da eficiência de carboxilação. O teor de carboidrato total (sacarose + açúcares redutores + amido) em plantas sem estresse foi maior em 'Trifoliata', e entre os tratamentos com deficiência hídrica foi sempre inferior. As massas secas das plantas sem deficiência hídrica foram maiores, em ambos os porta-enxertos. Entre os tratamentos irrigados e não irrigados, o comprimento das raízes dentro de um mesmo tipo de porta-enxerto foram semelhantes. Porém, o comprimento das raízes de laranjeira 'Valência' sobre 'Cravo' foi significativamente maior. Mesmo sob deficiência hídrica e grande queda da produção fotossintética, as raízes permaneceram crescendo, possivelmente às expensas de substrato mobilizado de outros órgãos.

The growth and distribution of the root system affect the response of the plants to water deficit. This work aim at the to evaluation of 'Valencia' orange budded on 'Rangpur<FONT FACE=Symbol>¢</FONT> lime and Poncirus trifoliata ('Trifoliata') as to root growth, gas exchange (CO2 and H2O), leaf water potential and distribution of carbohydrates in several organs, in plants submitted to water deficit. Plants were transplanted to 32 rizotrons, which allowed root visualization of the roots. Sixteen plants in each rootstock were submitted to irrigation and the other 16 remained without irrigation. Water deficit was induced withholding the water supply. Stomatal conductance declined after the fourth day without irrigation, causing a reduction of the photosynthesis, the transpiration and the carboxilation efficiency. The total carbohydrate content (sucrose + reducing sugars + starch) in plants without water stress was greater in 'Trifoliata', and among the water deficit treatments it was always less. The dry phytomass of the plants without water deficit was greater in both rootstocks. Among the irrigated and non irrigated treatments, the length of the roots same of rootstocks was similar. However, the root lengths of plants on 'Rangpur' lime were significantly greater than that on 'Trifoliata'. Even under water deficit and great decrease of the photosynthetic production, the roots maintained growth, possibly at the expenses of mobilized substrates of other plant parts.

A clorose variegada dos citros (CVC) é uma doença que tem promovido sérios prejuízos aos laranjais das regiões Norte e Nordeste do Estado de São Paulo, onde a deficiência hídrica e as altas temperaturas são mais frequentes. Assim, este trabalho objetivou a avaliação do efeito da deficiência hídrica no desenvolvimento de sintomas fisiológicos em laranjeira 'Natal' com CVC. Foram realizadas medidas do potencial da água na folha, transpiração, condutância estomática e assimilação de CO2, em laranjeiras em condições naturais e submetidas à irrigação. O delineamento experimental foi em blocos ao acaso com cinco repetições. A condutância estomática, a transpiração diária e o potencial da água na folha foram menores nas plantas com CVC. A assimilação diária de CO2 foi menor nas laranjeiras com CVC mesmo quando irrigadas. De fato, a irrigação diminuiu o efeito da CVC, porém não impediu o estabelecimento da doença em laranjeiras inoculadas com Xylella fastidiosa. Em relação aos demais tratamentos, as plantas infectadas e mantidas sob condições naturais (sem irrigação) apresentaram maior comprometimento das trocas gasosas, mesmo quando as avaliações fisiológicas foram feitas em período úmido (verão).

Citrus variegated chlorosis (CVC) is a disease that has caused serious economical losses in citrus grove located in the North and Northeastern regions of São Paulo State, where water deficiency and high temperature occur frequently. Therefore, the aim of this work was to evaluate the influence of water deficiency on the development of physiological symptoms in 'Natal' sweet orange plants with CVC. Measurements of leaf water potential, transpiration, stomatal conductance e CO2 assimilation were taken in plants under natural conditions and submitted to irrigation. The experimental design was in randomized blocks, with five replications. Stomatal conductance, daily transpiration and leaf water potential were lower in CVC-affected plants. The daily CO2 assimilation was reduced in CVC-affected plants, even in irrigated ones. In fact, irrigation decreased the negative effects of CVC, however, it did not prevent disease establishment in sweet orange plants inoculated with Xylella fastidiosa. Compared to other treatments, infected plants submitted to natural conditions (without irrigation) exhibited higher constrain of leaf gas exchange, even when measurements were taken during humid period (summer).

CitEST project resulted in the construction of cDNA libraries from different Citrus sp. tissues under various physiological conditions. Among them, plantlets of Rangpur lime were exposed to hydroponic conditions with and without water stress using PEG6000. RNA from roots was obtained and generated a total of 4,130 valid cDNA reads, with 2,020 from the non-stressed condition and 2,110 from the stressed set. Bioinformatic analyses measured the frequency of each read in the libraries and yielded an in silico transcriptional profile for each condition. A total of 40 contigs were differentially expressed and allowed to detect up-regulated homologue sequences to well known genes involved in stress response, such as aquaporins, dehydrin, sucrose synthase, and proline-related synthase. Some sequences could not be classified by using FunCat and remained with an unknown function. A large number of sequences presented high similarities to annotated genes involved with cell energy, protein synthesis and cellular transport, suggesting that Rangpur lime may sustain active cell growth under stressed condition. The presence of membrane transporters and cell signaling components could be an indication of a coordinated morphological adaptation and biochemical response during drought, helping to explain the higher tolerance of this rootstock to water stress.

O objetivo do presente estudo foi avaliar como a quantidade de frutos (carga pendente) em laranjeira 'Valência' em um ano afeta o teor de carboidratos em folhas, o crescimento vegetativo, o florescimento, a frutificação e a produção de frutos na safra do ano seguinte, em plantas submetidas ou não à irrigação. O experimento foi desenvolvido em duas fases. Na primeira fase do experimento, em metade das laranjeiras irrigadas e não irrigadas foram retirados todos os frutos. O experimento foi realizado em um delineamento fatorial 2 x 2 com seis repetições. Analisaram os resultados por meio de análise de variância e as médias foram comparadas pelo teste Tukey a 5%. A presença de frutos afetou o crescimento vegetativo e a intensidade de florescimento. Na segunda fase de experimento, as mesmas laranjeiras em que se retiraram os frutos tiveram maior produção. Em laranjeiras com maior produção de frutos, observou-se menor intensidade de florescimento, demonstrando que foi parcialmente inibido por eles. Nos resultados não houve evidências de que o teor de carboidratos tivesse limitado o florescimento. Não houve evidências também que a menor intensidade de florescimento foi devida à competição por carboidratos com os frutos. As baixas temperaturas do inverno foram suficientes para induzir o florescimento nas plantas irrigadas. Porém, o florescimento foi mais intenso quando, no período de indução, também ocorreu deficiência hídrica, nas plantas não irrigadas. O número fixado de frutos e o crescimento inicial dos frutos são limitados pela disponibilidade de carboidratos.

The objective of the present study was to evaluate how the crop fruit load status in orange tree 'Valência' throughout a year affects the carbohydrate content in leaves, the vegetative growth, the flowering, the fruit set, and the yield in the following season, in plants with and without irrigation. The experiment was conduced in two steps in field condition. In the first step (February, 2004) a half of both, irrigated and non irrigated plants, had all the fruits removed. The experimental design was a 2 x 2 factorial with six repetitions. The results were subjected to analyses of variance and means were compared by the Tukey test at 5%. The presence of fruits affected the vegetative growth and the flowering intensity. In second step, the same oranges trees that have been defruited presented higher yield. These plants showed a less intense flowering, indicating that flowering was partially inhibited by the fruits. Our results did not show any evidence that the carbohydrates content could have limited flowering intensity due to a competition with the fruits for carbohydrates. The low winter air temperatures were suitable to induce flowering in the irrigated orange trees. However flowering was more intense in case of water deficit in non irrigated plants during the induction crop phase. The number of bearing fruits and the initial growth of fruits are limited by the availability of carbohydrates.

O objetivo deste trabalho foi avaliar os efeitos da clorose variegada dos citros (CVC), no fluxo de seiva, trocas gasosas e atividade fotoquímica em laranjeira 'Natal', com e sem CVC, em condição de campo. O curso diário do fluxo de seiva, potencial da água na folha, assimilação de CO2, transpiração, condutância estomática e eficiência quântica máxima e efetiva do fotossistema II foram avaliados. O delineamento experimental foi em blocos ao acaso com cinco repetições. O fluxo de seiva foi 1,9 vez superior nas plantas sadias em relação às doentes. Em plantas doentes ocorreu queda de 43, 28 e 33% na assimilação de CO2, condutância estomática e transpiração, respectivamente. As plantas com CVC apresentaram fotoinibição dinâmica. Uma vez que a eficiência quântica efetiva apresentou um padrão de resposta semelhante, durante o dia, em ambos os tratamentos, o efeito protetor da fotorrespiração no aparato fotoquímico em plantas com CVC é discutido. As quedas de assimilação de CO2, transpiração e de fluxo de seiva, nas plantas com CVC, foram decorrentes do menor valor da condutância estomática, possivelmente causado pela colonização dos vasos do xilema pela Xylella fastidiosa.

The objective of this work was to evaluate the effects of citrus variegated chlorosis (CVC) on sap flow, gas exchanges and photochemical activity in 'Natal' sweet orange plants with and without CVC under field condition. Diurnal courses of sap flow, leaf water potential, CO2 assimilation rate and transpiration, stomatal conductance, potential and effective quantum efficiency of photosystem II were evaluated. The experiment was arranged in a random block design with five repetitions. Healthy plants showed sap flow values around 1.9 times higher than injured ones. Injured plants exhibited reductions of 43, 28 and 33% in CO2 assimilation rate, stomatal conductance and leaf transpiration, respectively. CVC-affected plants showed dynamic photoinhibition. Since healthy and injured plants showed similar diurnal course of effective quantum efficiency, the possible influence of photorespiration on photochemical apparatus in CVC-affected plants is discussed. Reductions in CO2 assimilation rate, transpiration and sap flow of injured plants were induced by low stomatal conductance values, which was probably due to the xylem vessel colonization by Xylella fastidiosa.

Foram avaliadas as respostas das trocas gasosas à irradiância, à temperatura, ao déficit de pressão de vapor e à concentração interna de CO2 em plantas jovens de laranjeira 'Valência', tangor 'Murcote' e lima ácida 'Tahiti', sob condições controladas. As taxas máximas de assimilação de CO2 foram de 9,8, 12,8 e 13,0 µmol m-2 s-1 em 'Valência', 'Murcote' e 'Tahiti', respectivamente. Diferenças na taxa de assimilação de CO2 foram relacionadas com a condutância estomática e com a eficiência instantânea de carboxilação. A saturação da fotossíntese pela luz foi em torno de 750 µmol m-2 s-1 em 'Valência'. Em 'Murcote' e 'Tahiti', não houve um ponto evidente de saturação lumínica, pois houve pequenos aumentos da assimilação de CO2 acima de 1.000 µmol m-2 s-1. Os pontos de compensação de CO2 foram 4,8, 5,8 e 5,4 Pa em 'Valência', 'Murcote' e 'Tahiti', respectivamente. Temperaturas das folhas entre 25ºC e 30ºC corresponderam à faixa ótima para a fotossíntese em 'Valência' e ao redor de 30ºC em 'Murcote' e 'Tahiti'. Quedas das taxas de assimilação de CO2 em temperaturas acima ou abaixo da ideal ocorreram em razão de quedas parciais na condutância estomática e na eficiência instantânea de carboxilação. A taxa de assimilação de CO2 também decresceu com o aumento do déficit de pressão de vapor de 1,5 para 3,5 kPa. Este efeito foi mais acentuado quando a temperatura aumentou de 28ºC para 35ºC.

Gas exchange responses to irradiance, temperature, air vapor pressure deficit and intercellular CO2 concentration were evaluated in young plants of sweet orange 'Valência', tangor 'Murcote' and acid lime 'Tahiti' plants, under controlled conditions. Maximum rates of CO2 assimilation were around 9.8, 12.8 and 13.0 µmol m-2 s-1 , respectively, for 'Valência', 'Murcote' and 'Tahiti', and these differences were related to stomatal conductance and instantaneous carboxylation efficiency. Light saturation of photosynthesis was around 750 µmol m-2 s-1 for 'Valência', whereas 'Murcote' and 'Tahiti' did not show evident light saturation, exhibiting small increases of CO2 assimilation above 1,000 µmol m-2 s-1 . The CO2 compensation point was 4.8, 5.8 and 5.4 Pa for 'Valência', 'Murcote' and 'Tahiti', respectively, indicating differences in photorespiration of these citrus species. Leaf temperatures between 25ºC and 30ºC were optimum for photosynthesis of 'Valência', whereas this optimum was around 30ºC for 'Murcote' and 'Tahiti'. At temperatures above or below the optimum range, CO2 assimilation was reduced by partial decrease of stomatal conductance and instantaneous carboxylation efficiency. Reduced CO2 assimilation rate was also caused by increasing vapor pressure deficit from 1.5 to 3.5 kPa, and this effect enhanced when temperature increased from 28ºC to 35ºC.

Laranjeiras 'Pêra' de dois anos e meio de idade enxertadas em limoeiros 'Cravo' foram cultivadas em vasos de 100 L com solo e submetidas ao estresse hídrico, pela suspensão da irrigação. Valores de assimilação de CO2 (A), transpiração (E) e condutância estomática (g s) começaram a declinar a partir do sétimo dia de estresse, embora o potencial da água na folha às 6 a.m. (psipd) e às 2 p.m. (psi2) começaram a declinar a partir do quinto dia de deficiência hídrica. A concentração interna de CO2 (Ci) das plantas estressadas aumentou a partir do mesmo dia, atingindo uma concentração máxima no dia de estresse mais severo. Assim, a eficiência de carboxilação dessas plantas, verificada pela relação A/Ci foi menor nesse dia, não ocorrendo recuperação dessa razão mesmo dez dias após a reidratação. Até o quinto dia após a reirrigação, somente o psipd e o psi2 se recuperaram, sendo semelhantes aos das plantas controle. Quando o potencial da água na folha diminuiu, ocorreu uma tendência de aumento da concentração de ácido abscísico (ABA) nas folhas; da mesma forma, foi possível verificar que a condutância estomática diminuiu em função do decréscimo em psi2. O acúmulo de ABA e o fechamento estomático ocorreram quando psi2 foi menor que -1.0 MPa. A deficiência hídrica em laranjeiras 'Pêra' aumentou o conteúdo de ABA, com conseqüente fechamento estomático e decréscimo em psi2.

Thirty-month-old 'Pêra' orange trees grafted on 'Rangpur' lemon trees grown in 100 L pots were submitted to water stress by the suspension of irrigation. CO2 assimilation (A), transpiration (E) and stomatal conductance (g s) values declined from the seventh day of stress, although the leaf water potential at 6:00 a.m. (psipd) and at 2:00 p.m. (psi2) began to decline from the fifth day of water deficiency. The CO2 intercellular concentration (Ci) of water-stressed plants increased from the seventh day, reaching a maximum concentration on the day of most severe stress. The carboxylation efficiency, as revealed by the ratio A/Ci was low on this day and did not show the same values of non-stressed plants even after ten days of rewatering. After five days of rewatering only psi pd and psi2 were similar to control plants while A, E and g s were still different. When psi2 decreases, there was a trend for increasing abscisic acid (ABA) concentration in the leaves. Similarly, stomatal conductance was found to decrease as a function of decreasing psi2. ABA accumulation and stomatal closure occurred when psi2 was lower than -1.0 MPa. Water stress in 'Pera´ orange trees increased abscisic acid content with consequent stomatal closure and decreased psi2 values.

Plantas com clorose variegada dos citros (CVC), uma doença causada pela bactéria Xylella fastidiosa, restrita ao xilema, apresentam folhas com sintomas de deficiência hídrica, associados com diminuição na fotossíntese líquida e na taxa de transpiração. Utilizando-se plantas sadias e com CVC de laranjeira 'Pêra' sobre limoeiro 'Cravo', as variáveis de trocas gasosas foram medidas com sistema portátil aberto de fotossíntese. Todas as plantas foram irrigadas e o potencial da água na folha (Yw) medido pela técnica psicrométrica de termopar isopiéstico. Fotossíntese líquida (A) vs. concentração interna de CO2 na folha (curvas A/Ci) foram analisadas. O efeito relativo da resistência estomática sobre a fotossíntese (S%) e a estimativa da eficiência de carboxilação foram calculados. Taxas de fotossíntese e transpiração, condutância estomática e concentração interna de CO2 na folha (Ci) foram também medidas quando se variou a densidade de fluxo de fótons fotossinteticamente ativos (DFFFA). Os valores de S% foram 30 % maiores nas plantas doentes, comparados às sadias, e seu ponto de compensação de luz também foi maior e o ponto de saturação de luz nas plantas com CVC foi duas vezes menor. O menor Yw nas plantas doentes reforçou a hipótese de oclusão do xilema, que provavelmente causou o menor suprimento de água para o mesofilo, diminuindo as taxas de fotossíntese e de transpiração. Todavia, houve também uma redução nas atividades metabólicas da fotossíntese, representada pela baixa eficiência de carboxilação e distúrbios fotoquímicos detectados nas plantas doentes.

Plants with citrus variegated chlorosis (CVC), a disease caused by the xylem-limited bacteria Xylella fastidiosa, have leaves with water deficiency symptoms and are associated with decreases on the net photosynthesis and transpiration rates. Using healthy and CVC-affected 'Pêra' sweet orange plants on 'Rangpur' lime rootstock, the leaf gas exchange variables were measured with an open-gas portable photosynthesis system. All plants were watered and the leaf water potential (Yw) was measured by isopiestic thermocouple psychrometric technique. The net photosynthesis (A) vs. internal leaf CO2 concentration (A/Ci curves) was analyzed. The relative effect of stomatal resistance on photosynthesis (S%) and the estimation of carboxylation efficiency were calculated. The rates of photosynthesis and transpiration, stomatal conductance, and internal leaf CO2 concentration (Ci) were also measured while varying the photosynthetic photon flux density (PPFD). The S% values were approximately 30 % greater in infected plants when compared to healthy ones. The light compensation point for diseased plants was higher than in the healthy ones, and the saturation light point in plants with CVC was twofold lower. The lower Yw in diseased plants favours the hypothesis of xylem occlusion, which probably caused a lower water supply to the mesophyll, thus decreasing the photosynthesis and transpiration rates. Nevertheless, there was also a reduction in the photosynthetic metabolic activities, represented by lower carboxylation efficiency and photochemical disturbances that were detected in diseased plants.