Physiological, cellular and molecular aspects of the desiccation tolerance in Anadenanthera colubrina seeds during germination / Aspectos fisiológicos, celulares e moleculares da tolerância à dessecação em sementes de Anadenanthera colubrina durante a germinação

Abstract During germination, orthodox seeds become gradually intolerant to desiccation, and for this reason, they are a good model for recalcitrance studies. In the present work, physiological, biochemical, and ultrastructural aspects of the desiccation tolerance were characterized during the germination process of Anadenanthera colubrina seeds. The seeds were imbibed during zero (control), 2, 8, 12 (no germinated seeds), and 18 hours (germinated seeds with 1 mm protruded radicle); then they were dried for 72 hours, rehydrated and evaluated for survivorship. Along the imbibition, cytometric and ultrastructural analysis were performed, besides the extraction of the heat-stable proteins. Posteriorly to imbibition and drying, the evaluation of ultrastructural damages was performed. Desiccation tolerance was fully lost after root protrusion. There was no increase in 4C DNA content after the loss of desiccation tolerance. Ultrastructural characteristics of cells from 1mm roots resembled those found in the recalcitrant seeds, in both hydrated and dehydrated states. The loss of desiccation tolerance coincided with the reduction of heat-stable proteins.

Resumo Durante a germinação, sementes ortodoxas tornam-se gradualmente intolerantes à dessecação, e por isso podem ser utilizadas como modelo para o estudo da recalcitrância. No presente trabalho realizou-se uma caracterização dos aspectos fisiológicos, bioquímicos e ultraestruturais da perda da tolerância à dessecação de sementes de Anadenanthera colubrina em processo germinativo. Para isso as sementes foram embebidas durante 0 (controle), 2,8,12 e aproximadamente 18 horas (sementes germinadas com 1 mm de radícula), secas por 72 horas, reidratadas e a sobrevivência avaliada. Ao longo da embebição foram realizadas análises citométricas, ultraestruturais e extração de proteínas resistentes ao calor e após embebição e secagem foram avaliados danos ultraestruturais. A tolerância à dessecação foi totalmente perdida após a protrusão radicular. Não houve aumento do conteúdo de DNA 4C quando a tolerância à dessecação foi perdida. Características ultraestruturais de células de radículas de 1 mm assemelharam-se às encontradas em sementes recalcitrantes tanto no estado hidratado quanto desidratado. A perda da tolerância à dessecação coincidiu com a redução do conteúdo de proteínas resistentes ao calor.

Disseminated cutaneous histoplasmosis and AIDS: Case report

Histoplasmosis is caused by the dimorphic fungus Histoplasma capsulatum. It manifests by the presence of fever as the only symptom in most individuals. The disease may present as self-limited pneumonia, or as an hematogenous widespread fungal infection with a potentially fatal outcome in elderly individuals and people with compromised T-cell mediated immunity. Here, we report a case of disseminated cutaneous histoplasmosis in a patient with AIDS. The patient was a 33 year old male homosexual, intravenous drug user, who had been diagnosed with HIV infection 5 years earlier. He has in good health, but had erythematous papules and pustules in the skin of the scalp, face, back, thighs, abdomen, palms, and soles. He was placed on anti-retroviral therapy, fluconazole for mucosal candidiasis, trimethoprim/sulfamethoxazole for pneumocystis prophylaxis, and antibiotics for the skin pustules. The skin lesions improved remarkably within 14 days. He was discharged and soon lost to follow-up. After his discharge, skin biopsy and fungal culture results revealed H. capsulatum. He was seen again 1 year later. the interim history revealed that he had taken fluconazole 100 mg/day for 1 month and fluconazole 150 mg/week for 7 months. He had not continued anti-retroviral therapy, nor taken other antifungal drugs. The clinical evolution of the disease was exceptional in that there was disappearance of all the skin lesions attributed to histoplasmosis with fluconazole. Although itraconazole remains the drug of choice for histoplasmosis. Cutaneous histoplasmosis should be considered in the differential diagnosis of atypical cutaneous lesions in individuals infected with HIV.