761 research outputs found

    Ex vitro hairy root induction in detached peanut leaves for plant-nematode interaction studies.

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    Abstract Background Peanut (Arachis hypogaea) production is largely affected by a variety of abiotic and biotic stresses, including the root-knot nematode (RKN) Meloidogyne arenaria that causes yield losses worldwide. Transcriptome studies of wild Arachis species, which harbor resistance to a number of pests and diseases, disclosed several candidate genes for M. arenaria resistance. Peanut is recalcitrant to genetic transformation, so the use of Agrobacterium rhizogenes-derived hairy roots emerged as an alternative for in-root functional characterization of these candidate genes. Results The present report describes an ex vitro methodology for hairy root induction in detached leaves based on the well-known ability of peanut to produce roots spontaneously from its petiole, which can be maintained for extended periods under high-humidity conditions. Thirty days after infection with the A. rhizogenes ‘K599’ strain, 90% of the detached leaves developed transgenic hairy roots with 5 cm of length in average, which were then inoculated with M. arenaria. For improved results, plant transformation, and nematode inoculation parameters were adjusted, such as bacterial cell density and growth stage; moist chamber conditions and nematode inoculum concentration. Using this methodology, a candidate gene for nematode resistance, AdEXLB8, was successfully overexpressed in hairy roots of the nematode-susceptible peanut cultivar ‘Runner’, resulting in 98% reduction in the number of galls and egg masses compared to the control, 60 days after M. arenaria infection. Conclusions This methodology proved to be more practical and cost-effective for functional validation of peanut candidate genes than in vitro and composite plant approaches, as it requires less space, reduces analysis costs and displays high transformation efficiency. The reduction in the number of RKN galls and egg masses in peanut hairy roots overexpressing AdEXLB8 corroborated the use of this strategy for functional characterization of root expressing candidate genes. This approach could be applicable not only for peanut–nematode interaction studies but also to other peanut root diseases, such as those caused by fungi and bacteria, being also potentially extended to other crop species displaying similar petiole-rooting competence

    De Novo HIV Infection Diagnoses in a Department of Dermatology and Venereology in Lisbon, Portugal

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    BACKGROUND: Portugal has the highest prevalence rate of HIV infection in Western Europe. The proportion of patients with a late diagnosis, carried out in full-blown AIDS stage, remains high. Skin and mucous membrane manifestations are not rare in these patients. OBJECTIVE: A demographic, clinical, and laboratorial characterization of patients with de novo HIV infection diagnosis made in the Department of Dermatology and Venereology of a central hospital in Lisbon, Portugal. METHODS: Retrospective review of medical records of adult patients newly diagnosed with HIV infection (reactive immunoassay for antibodies to HIV-1/HIV-2 or HIV p24 antigen) in the Dermatology and Venereology Department of a Portuguese central hospital in the period between January 2005 and December 2013. RESULTS: During the study period, 97 new cases were diagnosed, 70 men and 27 women. The median age at diagnosis was 36 years. Of the total, 50 cases were diagnosed with a concomitant sexually transmitted infection (STI), more frequently syphilis and ano-genital HPV infection. The remaining 47 patients were diagnosed with other dermatological conditions such as prurigo nodularis, psoriasis, and Kaposi's sarcoma. The duration of complaints that lead to medical attention ranged from <1 week to 8 years, being significantly lower in patients diagnosed with a concomitant STI (p < 0.01). Basal viral load was also lower in this group of patients (p < 0.05). Of all the new diagnosed cases, 80% of patients are currently retained in care. CONCLUSION: This study grants a descriptive overview of de novo HIV infection diagnoses performed by dermatovenereologists in a central hospital in Lisbon, Portugal. As in the past, the importance of Dermato-Venereology for HIV infection diagnosis remains present in daily clinical practice

    Hibridização genômica in situ em triticeae: um enfoque metodológico.

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    bitstream/CNPT-2010/40760/1/p-co270.pd

    Genetic parameters and selection of sugarcane in early selection stages for resistance to sugarcane borer Diatraea saccharalis.

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    A T1 (sugarcane population originating from true seeds) and T2 (first sugarcane clonal stage) population were used to estimate genetic parameters and compare selection strategies for Diatraea saccharalis (Lepidoptera: Crambidae) resistance in sugarcane. In the T1 stage, heritability at the family mean level (h²=0.77) was higher than individual genotype heritability (h²=0.16), and the additive genetic effect was more important for sugarcane borer resistance than non-additive effects. In addition, there was high genotypic variance among and within full-sib families. In the T2 population, genotypic variance was high, and heritability at the clone mean level was moderate (h²=0.61). We can conclude that family experiments enable selection of more promising families and parents for borer resistance. However, due to high genotypic variance within families, family selection at the T1 stage must be followed by clone selection at the T2 stage
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