RESUMO
To understand carbon partitioning in roots and nodules of Datisca glomerata, activities of sucrose-degrading enzymes and sugar transporter expression patterns were analyzed in both organs, and plasmodesmal connections between nodule cortical cells were examined by transmission electron microscopy. The results indicate that in nodules, the contribution of symplastic transport processes is increased in comparison to roots, specifically in infected cells which develop many secondary plasmodesmata. Invertase activities are dramatically reduced in nodules as compared to roots, indicating that here the main enzyme responsible for the cleavage of sucrose is sucrose synthase. A high-affinity, low-specificity monosaccharide transporter whose expression is induced in infected cells prior to the onset of bacterial nitrogen fixation, and which has an unusually low pH optimum and may be involved in turgor control or hexose retrieval during infection thread growth.
Assuntos
Metabolismo dos Carboidratos , Cucurbitaceae/metabolismo , Fixação de Nitrogênio/fisiologia , Plasmodesmos/metabolismo , Nódulos Radiculares de Plantas/metabolismo , Cucurbitaceae/citologia , Cucurbitaceae/genética , Cucurbitaceae/ultraestrutura , Regulação da Expressão Gênica de Plantas , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Cinética , Proteínas de Transporte de Monossacarídeos/genética , Proteínas de Transporte de Monossacarídeos/metabolismo , Plasmodesmos/enzimologia , Plasmodesmos/ultraestrutura , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Nódulos Radiculares de Plantas/enzimologia , Nódulos Radiculares de Plantas/genética , Saccharomyces cerevisiae/metabolismoRESUMO
The identification of specific genetic loci that contribute to inflammatory and autoimmune diseases has proved difficult due to the contribution of multiple interacting genes, the inherent genetic heterogeneity present in human populations, and a lack of new mouse mutants. By using N-ethyl-N-nitrosourea (ENU) mutagenesis to discover new immune regulators, we identified a point mutation in the murine phospholipase Cg2 (Plcg2) gene that leads to severe spontaneous inflammation and autoimmunity. The disease is composed of an autoimmune component mediated by autoantibody immune complexes and B and T cell independent inflammation. The underlying mechanism is a gain-of-function mutation in Plcg2, which leads to hyperreactive external calcium entry in B cells and expansion of innate inflammatory cells. This mutant identifies Plcg2 as a key regulator in an autoimmune and inflammatory disease mediated by B cells and non-B, non-T haematopoietic cells and emphasizes that by distinct genetic modulation, a single point mutation can lead to a complex immunological phenotype.
Assuntos
Autoimunidade , Cálcio/metabolismo , Inflamação/genética , Mutação Puntual , Fosfolipases Tipo C/genética , Animais , Artrite Experimental/genética , Artrite Experimental/imunologia , Linfócitos B/metabolismo , Sequência de Bases , Células da Medula Óssea/citologia , Dermatite/genética , Dermatite/imunologia , Masculino , Camundongos , Dados de Sequência Molecular , Fosfolipase C gama , Fosfolipases Tipo C/metabolismo , Regulação para CimaRESUMO
The vestibular system of the inner ear is responsible for the perception of motion and gravity. Key elements of this organ are otoconia, tiny biomineral particles in the utricle and the saccule. In response to gravity or linear acceleration, otoconia deflect the stereocilia of the hair cells, thus transducing kinetic movements into sensorineural action potentials. Here, we present an allelic series of mutations at the otoconia-deficient head tilt (het) locus, affecting the gene for NADPH oxidase 3 (Nox3). This series of mutations identifies for the first time a protein with a clear enzymatic function as indispensable for otoconia morphogenesis.
Assuntos
Mutação , NADPH Oxidases/genética , Doenças Vestibulares/genética , Vestíbulo do Labirinto/anormalidades , Vestíbulo do Labirinto/enzimologia , Animais , Mapeamento Cromossômico , Genes Recessivos , Sensação Gravitacional , Camundongos , Camundongos Mutantes , Morfogênese/genética , NADPH Oxidases/fisiologia , Propriocepção , Doenças Vestibulares/enzimologia , Vestíbulo do Labirinto/anatomia & histologiaRESUMO
Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein.