RESUMO
Paspalum dilatatum (common name dallisgrass), a productive C4 grass native to South America, is an important pasture grass found throughout the temperate warm regions of the world. It is characterized by its tolerance to frost and water stress and a higher forage quality than other C4 forage grasses. P. dilatatum includes tetraploid (2n = 40), sexual, and pentaploid (2n = 50) apomictic forms, but is predominantly cultivated in an apomictic monoculture, which implies a high risk that biotic and abiotic stresses could seriously affect the grass productivity. The obtention of reproducible and efficient protocols of regeneration and transformation are valuable tools to obtain genetic modified grasses with improved agronomics traits. In this review, we present the current regeneration and transformation methods of both apomictic and sexual cultivars of P. dilatatum, discuss their strengths and limitations, and focus on the perspectives of genetic modification for producing new generation of forages. The advances in this area of research lead us to consider Paspalum dilatatum as a model species for the molecular improvement of C4 perennial forage species.
RESUMO
The neuregulin receptor tyrosine kinase Erb-b4, initially linked to early cardiac development, is shown here to play a critical role in adult cardiac function. In wild-type mice, Erb-b4 protein localized to Z lines and to intercalated disks, suggesting a role in subcellular and intercellular communications of cardiomyocytes. Conditional inactivation of erb-b4 in ventricular muscle cells led to a severe dilated cardiomyopathy, characterized by thinned ventricular walls with eccentric hypertrophy, reduced contractility, and delayed conduction. This cardiac dysfunction may account for premature death in adult erb-b4-knockout mice. This study establishes a critical role for Erb-b4 in the maintenance of normal postnatal cardiac structure and function.
Assuntos
Cardiomiopatia Dilatada/fisiopatologia , Receptores ErbB/genética , Receptores ErbB/metabolismo , Animais , Cardiomegalia/genética , Cardiomegalia/fisiopatologia , Cardiomiopatia Dilatada/genética , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Miocárdica , Miocárdio/metabolismo , Miocárdio/patologia , Receptor ErbB-4 , Transdução de SinaisRESUMO
Patients with chronic Chagas' heart disease (cChHD) develop a strong IgG response against the C-terminal region of the Trypanosoma cruzi ribosomal P2beta protein (TcP2beta). These antibodies have been shown to exert an in vitro chronotropic effect on cardiocytes through stimulation of the beta1-adrenergic receptor (beta1-AR). Moreover, the presence of antibodies recognizing the TcP2beta C-terminus was associated with cardiac alterations in mice immunized with the corresponding recombinant protein. Here, we demonstrate that DNA immunization could be used to modulate the specificity of the anti-TcP2beta humoral response in order to avoid the production of pathogenic antibodies. After DNA injection, we detected IgG antibodies that were directed only to internal epitopes of the TcP2beta molecule and that did not exert anti-beta1-AR functional activity, measured as an increase in intracellular cAMP levels of transfected COS-7 cells. Accordingly, DNA-immunized mice did not present electrocardiographic alterations. These data demonstrate that anti-TcP2beta antibodies elicited by DNA immunization are completely different in their specificity and functional activity from those produced during T. cruzi infection.