RESUMO
In mammals and Drosophila, apoptotic caspases are under positive control of the CED-4-like proteins Apaf-1 and ARK, respectively. In an EMS-mutagenesis screen, we isolated 33 ark mutants as recessive suppressors of hid-induced apoptosis. The ark mutants are loss-of-function alleles characterized by reduced developmental apoptosis. Using the phenotypic series of these alleles, we identified helical domain I in the nucleotide oligomerization domain as critical for ARK's apoptotic activity. Interestingly, the WD40 region may also have an unanticipated positive requirement for the apoptotic activity of ARK. Considering structural information, we discuss the roles of these domains for assembly and activity of the ARK apoptosome, and propose that the WD40 region is anti-apoptotic in the absence of apoptotic signals, and pro-apoptotic in the presence of such signals. Furthermore, a defined null allele reveals that ark is required for most, but not all apoptosis suggesting the existence of an ARK-independent apoptotic pathway.
Assuntos
Apoptose , Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Drosophila/embriologia , Alelos , Animais , Apoptossomas , Códon sem Sentido , Drosophila/química , Drosophila/citologia , Proteínas de Drosophila/genética , Metanossulfonato de Etila/farmacologia , Olho/citologia , Olho/embriologia , Feminino , Genes Reporter , Proteínas Inibidoras de Apoptose/fisiologia , Masculino , Mutagênese , Mutação de Sentido Incorreto , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Fenótipo , Estrutura Terciária de ProteínaRESUMO
Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation (i.e., no power-supply), and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond to an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. SAW radio transponders are advantageously placed on moving or rotating parts and in hazardous environments such as contaminated or high voltage areas. They also can be used for contactless measurements in high vacuum process chambers, under concrete, extreme heat, or strong radioactive radiation, where the use of conventional sensors is complicated, dangerous, or expensive. In this paper we discuss the principles of wireless passive SAW transponders and present a radio frequency interrogation unit and several passive radio SAW sensors developed for noncontact measurements of temperatures, pressures, torques, and currents.