RESUMEN
A viral gene, CpBV-CST1, was identified from a polydnavirus Cotesia plutellae bracovirus (CpBV). Its protein product was significantly toxic to lepidopteran insects. This study generated a transgenic tobacco plant expressing CpBV-CST1 Expression of transgene CpBV-CST1 was confirmed in T1 generation (second generation after transgenesis) in both mRNA and protein levels. Young larvae of Spodoptera exigua (Hübner) suffered high mortalities after feeding on transgenic tobacco. All 10 T1 transgenic tobacco plants had no significant variation in speed-to-kill. In order to further explore insect resistance of these transgenic tobaccos, bioassays were performed by assessing antixenosis and antibiosis. S. exigua larvae significantly avoided T1 plants in a choice test. Larvae fed with T1 plant exhibited significant decrease in protease activity in the midgut due to consuming CpBV-CST1 protein produced by the transgenic plant. Furthermore, the transgenic tobacco exhibited similar insect resistance to other tobacco-infesting insects, including a leaf-feeding insect, Helicoverpa assulta, and a sap-feeding insect, Myzus persicae These results demonstrate that a viral cystatin gene can be used to develop insect-resistant transgenic plant, suggesting a prospective possibility of expanding the current transgenic approach to high-valued crops.
Asunto(s)
Antibiosis , Áfidos/fisiología , Cistatinas/genética , Mariposas Nocturnas/fisiología , Nicotiana/fisiología , Polydnaviridae/genética , Proteínas Virales/genética , Animales , Áfidos/crecimiento & desarrollo , Cistatinas/metabolismo , Larva/crecimiento & desarrollo , Larva/fisiología , Mariposas Nocturnas/crecimiento & desarrollo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/fisiología , Polydnaviridae/metabolismo , Spodoptera/crecimiento & desarrollo , Spodoptera/fisiología , Nicotiana/genética , Proteínas Virales/metabolismoRESUMEN
Explicit evaluation of the accuracy and power of maximum likelihood and Bayesian methods for detecting site-specific positive Darwinian selection presents a challenge because selective consequences of single amino acid changes are generally unknown. We exploited extensive molecular and functional characterization of amino acid substitutions in the plant gene eIF4E to evaluate the performance of these methods in detecting site-specific positive selection. We documented for the first time a molecular signature of positive selection within a recessive resistance gene in plants. We then used two statistical platforms, Phylogenetic Analysis Using Maximum Likelihood and Hypothesis Testing Using Phylogenies (HyPhy), to look for site-specific positive selection. Their relative power and accuracy are assessed by comparing the sites they identify as being positively selected with those of resistance-determining amino acids. Our results indicate that although both methods are surprisingly accurate in their identification of resistance sites, HyPhy appears to more accurately identify biologically significant amino acids using our data set.
Asunto(s)
Sustitución de Aminoácidos , Factor 4E Eucariótico de Iniciación/genética , Enfermedades de las Plantas/genética , Plantas/genética , Selección Genética , Teorema de Bayes , Capsicum/genética , Biología Computacional , Factor 4E Eucariótico de Iniciación/química , Evolución Molecular , Genes de Plantas , Inmunidad Innata/genética , Solanum lycopersicum/genética , Pisum sativum/genética , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Alineación de SecuenciaRESUMEN
Hemothorax and chylothorax remain perplexing medical problems. The primary cause of hemothorax is trauma, whereas the primary cause of chylothorax is cancer. Most patients with hemothorax can be treated with chest tube drainage only. Early thoracotomy with thoracic duct ligation is recommended for patients with chylothorax when conservative treatment with chest tube drainage and hyperalimentation fails. Radiation therapy is the mainstay of treatment for chylothorax related to cancer. Video-assisted thoracoscopy may play an increasing role in the surgical treatment of both hemothorax and chylothorax.
