Expressão de genes do sistema antioxidante mediada por ácido abscísico em folhas de milho (Zea mays L.)

Abstract

O hormônio ácido abscísico (ABA) participa da sinalização celular em situações de estresse. Buscou-se, nesse estudo, verificar a expressão de genes envolvidos no sistema antioxidante em resposta ao ABA de uma variedade de milho com baixa produção de flavonoides (p1-ww). Foram aplicadas às plântulas concentrações crescentes de ABA, sendo controle (água), 10, 100 e 1000 ?M. As coletas das folhas medianas foram realizadas após 3, 6 e 12 horas de tratamento. As amostras foram usadas para posterior isolamento do RNA, síntese de cDNA e qRT-PCR. Foi realizada a quantificação relativa (método do ?Ct) dos transcritos de actina (act), Zm actina (Zmact), -glumamilcisteína sintetase ( -ecs), glutationa sintetase (gsh-s), glutationa redutase (gsr1), gluatationa S-transferase (gst23), ascorbato peroxidases (apx1 e apx2), catalases (cat1 e cat3) e superóxido dismutase (sod2), em relação aos transcritos de ?-tubulina (tub), gene de referência. O experimento foi repetido três vezes. Foram realizadas análises estatísticas pelo teste de Kruskal-Wallis, com 99% de significância e o grupo 1000 ?M de ABA foi excluído das análises por apresentar variação do transcrito tub. Os resultados mostraram que não houve modificação de expressão dos genes cat3, apx2 e gsr1 em resposta ao tratamento com ABA. Porém, os genes cat1, apx1, sod2, -ecs, gsh-s e gst23 mostraram expressão diferencial. O aumento significativo mais frequente ocorreu das amostras controle para as tratadas com 100 ?M de ABA, ocorrendo aumento após 3, 6 e 12 horas de tratamento dos genes act, Zmact, cat1 e gst23. Já para sod2 e -ecs houve aumento em 100 ?M de ABA após 6 e 12 horas, para gsh-s após 3 e 6 horas e para o transcrito de apx1 após 6 horas. O aumento observado, em uma variedade de milho com expressão diminuída de flavonoide, na expressão de 6 genes envolvidos no sistema antioxidante em resposta ao tratamento das folhas com 100 ?M de ABA, confirma que o ABA age como mediador do sistema antioxidante da célula vegetal <br>

The purpose of this work is to describe the knowledge and practice of mammography as well as to identify associated factors in adult (20 to 59 years old) and elderly women (from 60 years old on). Data was attained in two population studies with independent samples; one with adult women and the other with elder ones, both living in urban areas of Florianopolis (SC) city in 2009-10. Variable dependent on mammography knowledge was built according to the sum of adequate responses of nine questions about it, and varied from zero to nine for all adult and elder women who participated. Another dependent variable, an inadequate practice of mammography, was defined as the examination with periodicity over 1 year in women from 40 to 69 years old. For the knowledge analysis about mammography, the average of adequate responses was estimated and the prevalence for the inadequate practice. Average reasons of adequate responses of knowledge and prevalence reasons of inadequate practice were estimated as well as their respective confidence intervals of 95% per crude and adjusted Poisson regression. Among the adults, 23.1% answered all questions appropriatelu and the appropriate average was 7.2 (IC95%: 7.1-7.3). In the adjusted model we associated a higher age group, educational and income levels to the knowledge about mammography. The prevalence of inadequate practice in adults was 49.2% (IC95%:44.5-59.4); the fact of not having a private health insurance increased this prevalence and reduced a greater knowledge. For the elderly women, 15.3% answered all questions appropriately and the average of adequate responses was 6.4 (IC95%: 5.26.5) and factors associated to the adjusted model were related to a lower age group, increased educational and income levels, and the identification of mammography as the main diagnosed method for breast cancer. Prevalence of inadequate practice was 55.0% (IC95%:50.6-59.4) and associated factors belonged to the first income quartile, the lack of an educational background, the fact of not having a partner, and there was a reduction of such prevalence once the mammography knowledge increased. Mammography knowledge reduces the inadequate practice and must constantly be propagated among women, especially for those with lower educational and income levels.