The Form in Which Nitrogen Is Supplied Affects the Polyamines, Amino Acids, and Mineral Composition of Sweet Pepper Fruit under an Elevated CO2 Concentration.

We investigated the effect of supplying nitrogen, as NO3- or as NO3-/NH4+, on the composition of fruits of sweet pepper (Capsicum annuum L. cv. Melchor) plants grown with different CO2 concentrations ([CO2]): ambient or elevated (800 µmol mol-1). The results show that the application of NH4+ and high [CO2] affected the chroma related to the concentrations of chlorophylls. The concentrations of Ca, Cu, Mg, P, and Zn were significantly reduced in the fruits of plants nourished with NH4+, the loss of Fe being more dramatic at increased [CO2], which was also the case with the protein concentration. The concentration of total phenolics was increased by NH4+, being unaffected by [CO2]. Globally, the NH4+ was the main factor that affected fruit free amino acid concentrations. Polyamines were affected differently: putrescine was increased by elevated [CO2], while the response of cadaverine depended on the form of N supplied.

Interactive Effects of CO2 Concentration and Water Regime on Stable Isotope Signatures, Nitrogen Assimilation and Growth in Sweet Pepper.

Sweet pepper is among the most widely cultivated horticultural crops in the Mediterranean basin, being frequently grown hydroponically under cover in combination with CO2 fertilization and water conditions ranging from optimal to suboptimal. The aim of this study is to develop a simple model, based on the analysis of plant stable isotopes in their natural abundance, gas exchange traits and N concentration, to assess sweet pepper growth. Plants were grown in a growth chamber for near 6 weeks. Two [CO2] (400 and 800 µmol mol-1), three water regimes (control and mild and moderate water stress) and four genotypes were assayed. For each combination of genotype, [CO2] and water regime five plants were evaluated. Water stress applied caused significant decreases in water potential, net assimilation, stomatal conductance, intercellular to atmospheric [CO2], and significant increases in water use efficiency, leaf chlorophyll content and carbon isotope composition, while the relative water content, the osmotic potential and the content of anthocyanins did change not under stress compared to control conditions support this statement. Nevertheless, water regime affects plant growth via nitrogen assimilation, which is associated with the transpiration stream, particularly at high [CO2], while the lower N concentration caused by rising [CO2] is not associated with stomatal closure. The stable isotope composition of carbon, oxygen, and nitrogen (δ13C, δ18O, and δ15N) in plant matter are affected not only by water regime but also by rising [CO2]. Thus, δ18O increased probably as response to decreases in transpiration, while the increase in δ15N may reflect not only a lower stomatal conductance but a higher nitrogen demand in leaves or shifts in nitrogen metabolism associated with decreases in photorespiration. The way that δ13C explains differences in plant growth across water regimes within a given [CO2], seems to be mediated through its direct relationship with N accumulation in leaves. The changes in the profile and amount of amino acids caused by water stress and high [CO2] support this conclusion. However, the results do not support the use of δ18O as an indicator of the effect of water regime on plant growth.

Photosynthetic acclimation to elevated CO2 concentration in a sweet pepper (Capsicum annuum) crop under Mediterranean greenhouse conditions: influence of the nitrogen source and salinity.

In many plant species, long-term exposure to elevated CO2 concentration results in a reduction in photosynthetic capacity, known as acclimation. This process is mainly explained by a feedback inhibition mechanism. The supply of a fraction of the nitrogen (N) in the nutrient solution as NH4+ can play an important role in the maintenance of photosynthetic activity and could mitigate the acclimation process. The aims of the present work were to study the photosynthetic response of sweet pepper (Capsicum annuum L.) to CO2 enrichment in Mediterranean greenhouse conditions, throughout the crop growth cycle and to evaluate the supply of NH4+ in the nutrient solution as a strategy to enhance the long-term response to CO2 at different levels of salinity. The experiment was conducted in two identical greenhouses: one with CO2 enrichment according to the ventilation, maintaining a high concentration when the vents were closed and a near-atmospheric level when the vents were open and one without. Sweet pepper plants were grown in both greenhouses, being irrigated with two levels of water salinity and two N sources: (i) NO3- and (ii) NO3- plus NH4+. A reduction in the response of photosynthesis to high CO2 concentration was found in the enriched plants after 135 days of CO2 supply, with respect to the reference plants. The leaf photosynthesis rate measured at high CO2 concentration showed a closer relationship with the leaf N concentration than the non-structural carbohydrate concentration. The relative yield gain of the CO2-enriched plants progressively decreased after reaching a maximum value; this was probably associated with the photosynthetic acclimation process. This decrease was delayed by the use of NH4+ in the nutrient solution at low salinity. Knowledge of the crop phase when acclimation to high CO2 concentration occurs can be the basis for deciding when to impose an early cessation of CO2 application, as a strategy to improve the economic efficiency of CO2 supply in Mediterranean conditions.

Changes in the salinity tolerance of sweet pepper plants as affected by nitrogen form and high CO2 concentration.

The assimilation and availability of nitrogen in its different forms can significantly affect the response of primary productivity under the current atmospheric alteration and soil degradation. An elevated CO2 concentration (e[CO2]) triggers changes in the efficiency and efficacy of photosynthetic processes, water use and product yield, the plant response to stress being altered with respect to ambient CO2 conditions (a[CO2]). Additionally, NH4(+) has been related to improved plant responses to stress, considering both energy efficiency in N-assimilation and the overcoming of the inhibition of photorespiration at e[CO2]. Therefore, the aim of this work was to determine the response of sweet pepper plants (Capsicum annuum L.) receiving an additional supply of NH4(+) (90/10 NO3(-)/NH4(+)) to salinity stress (60mM NaCl) under a[CO2] (400µmolmol(-1)) or e[CO2] (800µmolmol(-1)). Salt-stressed plants grown at e[CO2] showed DW accumulation similar to that of the non-stressed plants at a[CO2]. The supply of NH4(+) reduced growth at e[CO2] when salinity was imposed. Moreover, NH4(+) differentially affected the stomatal conductance and water use efficiency and the leaf Cl(-), K(+), and Na(+) concentrations, but the extent of the effects was influenced by the [CO2]. An antioxidant-related response was prompted by salinity, the total phenolics and proline concentrations being reduced by NH4(+) at e[CO2]. Our results show that the effect of NH4(+) on plant salinity tolerance should be globally re-evaluated as e[CO2] can significantly alter the response, when compared with previous studies at a[CO2].

Lingual ulceration associated with retinoic acid syndrome during treatment of acute promyelocytic leukemia.

BACKGROUND: All-trans retinoic acid (ATRA) is routinely associated with chemotherapy for the treatment of acute promyelocytic leukemia (APL). Several reports of scrotal ulceration induced by this agent have been made in the recent years. AIMS: The aim of this article was to report the first case of a lingual ulceration associated with retinoic acid syndrome (RAS). MATHERIALS AND METHODS: We presented a 32-year-old man with a diagnosis of acute promyelocytic leukemia who received treatment with ATRA. He presented with febrile neutropenia and a lingual ulcer that did not respond to antibiotic and antifungal regimens. He developed weight gain, lower limb edema, polyserositis, and acute renal failure. Retinoic acid syndrome syndrome was diagnosed. RESULTS: An exhaustive attempt to exclude infectious causes was made performing repeated cultures, histologic examinations, and direct immunofluorescence for HSV. No causative agent was identified. Re-epithelialization of the ulcer was achieved with ATRA cessation and treatment with systemic steroids. DISCUSSION: As far as we are concerned, we report the first case of a lingual ulceration associated with RAS. CONCLUSION: It is important for dermatologists to recognize this cutaneous complication of ATRA as it poses many differential diagnoses in neutropenic patients.

Reactivation of Chagas' disease: cutaneous manifestations in two immunosuppressed patients.

BACKGROUND: Chagas' disease is a zoonosis caused by a protozoan agent, Trypanosoma cruzi. Patients undergoing immunosuppressive treatment due to organ transplant, malignancies, infections, or chemotherapy may reactivate a preexisting chronic or indeterminate Trypanosoma cruzi infection. METHODS: We present two transplant patients who underwent reactivation of Chagas' disease with cutaneous manifestations after an augmentation in their immunosuppressive therapy. A 38-year-old man was hospitalized on day 69 after receiving an allogeneic bone marrow transplant; he developed multiple painful erythematous plaques with diffuse borders, confined to the right cheek, trunk, thigh, elbows, and feet. A 59-year-old woman with a 14-year history of Chagasic cardiomyopathy presented one month after heart transplantation with a painful infiltrated purpuric plaque on the back of her right leg. RESULTS: In both cases, histologic examination of skin biopsies showed dermal infiltration with intrahistiocytic amastigotes. In one of the reported cases, the Strout method detected parasitemia. Treatments with nifurtimox (600 mg/d) in case 1 and benznidazole (400 mg/d) in case 2 were started. Fever and cutaneous lesions resolved immediately after seven days of treatment. CONCLUSIONS: Reactivation of Chagas' disease is a serious complication that usually occurs in immunocompromised patients. Clinical manifestations include febrile illness occasionally associated with painful skin lesions. Early diagnosis and proper treatment can significantly improve these patients' outcome.