RESUMO
The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the Cry1Ab toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the Cry1Ab toxin. The cost of F2 screen performed in the four countries varied from U.S. dollars 300 to dollars 1300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the Cry1Ab toxin. The frequency of resistance alleles were < 1.0 x 10(-3), < 1.6 x 10(-3), < 9.2 x 10(-3), and < 2.6 x 10(-2) in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was approximately 90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the Cry1Ab produced by the Mon810 maize in western and central Europe was 1.0 x 10(-4), with a 95% confidence interval of 0-3.0 x 10(-4).
Assuntos
Proteínas de Bactérias/toxicidade , Endotoxinas/toxicidade , Proteínas Hemolisinas/toxicidade , Lepidópteros/efeitos dos fármacos , Controle Biológico de Vetores/métodos , Animais , Toxinas de Bacillus thuringiensis , Custos e Análise de Custo , Resistência a Medicamentos , Europa (Continente) , Feminino , França , Alemanha , Lepidópteros/classificação , Lepidópteros/genética , Lepidópteros/fisiologia , Masculino , Controle Biológico de Vetores/economia , Reprodução/efeitos dos fármacos , Zea mays/parasitologiaRESUMO
The authors studied by histoenzymology and electron microscopy, repigmentation induced by oral photochemotherapy (8-MOP-UVA) in 4 patients with vitiligo. The presence of hypertrophic melanocytes was demonstrated in the middle and deep portions of certain centre of islands of repigmentation. Melanocytes comparable to these were also observed in the epidermis of the peripheral collerette in the island of repigmentation. No melanocytic mitosis could be seen in the repigmenting epidermis. Ultrastructural study showed that the melanocytes of the repigmented zones were hyperactive. The melanosomes which they synthesize have a slightly larger size than the melanosomes of the neighbouring healthy skin. Their mode of intrakeratinocyte grouping was not altered. These results suggest that the origin of the melanocytes which repigment the vitiliginous epidermis under the influence of PUVA derives probably from a melanocytic reservoir localized in the hair follicle.
Assuntos
Metoxaleno/uso terapêutico , Fotoquimioterapia , Vitiligo/tratamento farmacológico , Humanos , Melanócitos/citologia , Vitiligo/patologia , Vitiligo/radioterapiaRESUMO
Repigmentation induced by oral photochemotherapy (8-MOP + UV-A) in four patients with vitiligo has been studied by histochemical and ultrastructural techniques. Hypertrophic melanocytes were demonstrated both in the middle and deep portions of the hair follicles in the centre of islands of repigmentation and also in the epidermis of the expanding repigmenting border. Mitosis of melanocytes was absent in these areas. Ultrastructural study showed that the melanocytes of repigmented areas were hyperactive. The melanosomes were larger than those of surrounding healthy skin, although the mode of packaging was unaltered. These observations suggest that melanocytes repigmenting vitiliginous skin under the influence of oral photochemotherapy are derived from a melanocytic reservoir localized in the hair follicles.