RESUMO
The embryonic Drosophila midgut is enclosed by a latticework of longitudinal and circular visceral muscles. We find that these muscles are syncytial. Like the somatic muscles they are generated by the prior segregation of two populations of cells: fusion-competent myoblasts and founder myoblasts specialised to seed the formation of particular muscles. Visceral muscle founders are of two classes: those that seed circular muscles and those that seed longitudinal muscles. These specialisations are revealed in mutant embryos where myoblast fusion fails. In the absence of fusion, founders make mononucleate circular or longitudinal fibres, while their fusion-competent neighbours remain undifferentiated.
Assuntos
Proteínas de Drosophila , Proteínas de Membrana , Proteínas Musculares , Músculo Liso/citologia , Células-Tronco/fisiologia , Animais , Fusão Celular , Sistema Digestório/embriologia , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Perfilação da Expressão Gênica , Imunoglobulinas/genética , Proteínas de Insetos/genética , Músculo Liso/embriologia , Músculo Liso/metabolismo , Células-Tronco/citologiaAssuntos
Hospitais Pediátricos , Facilitação Social , Apoio Social , Adulto , Pessoal Técnico de Saúde/educação , Criança , Educação Continuada , Humanos , TexasRESUMO
Agrobacterium tumefaciens R10 was mutagenized by using the promoter probe transposon Tn5-gusA7, and a library of approximately 5,000 transcriptional fusions was screened for octopine-inducible patterns of gene expression. Twenty-one mutants carrying strongly inducible gusA fusions, 20 of which showed defects in the catabolism of octopine or its metabolites, were obtained. One group of mutants could not use octopine as a carbon source, while a second group of mutants could not utilize arginine or ornithine and a third group could not utilize octopine, arginine, ornithine, or proline as a carbon source. Utilization of these compounds as nitrogen sources showed similar but not identical patterns. Fifteen fusions were subcloned together with adjacent DNA. Sequence analysis and further genetic analysis indicated that insertions of the first group are localized in the occ region of the Ti plasmid. Insertions of the second group were localized to a gene encoding ornithine cyclodeaminase. This gene is very similar to, but distinct from, a homolog located on the Ti plasmid. This gene is located immediately downstream from a gene encoding an arginase. Genetic experiments indicated that this arginase gene is essential for octopine and arginine catabolism. Insertions of the third group was localized to a gene whose product is required for degradation of proline. We therefore have identified all steps required for the catabolism of octopine to glutamate.
Assuntos
Agrobacterium tumefaciens/genética , Arginina/análogos & derivados , Genes Bacterianos , Família Multigênica , Agrobacterium tumefaciens/metabolismo , Sequência de Aminoácidos , Amônia-Liases/genética , Arginase/genética , Arginina/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Cisteína/biossíntese , DNA Bacteriano , Regulação Bacteriana da Expressão Gênica , Dados de Sequência Molecular , Mutagênese Insercional , Prolina Oxidase/genética , Homologia de Sequência de Aminoácidos , Transcrição GênicaRESUMO
Postmortem changes in the pH of blood and selected tissues in rats were evaluated at intervals ranging from 2 min to 96 h. Cardiac blood pH was significantly and reproducibly decreased in all groups at all postmortem intervals, independent of the method of sacrifice used. A preliminary study using cardiac blood obtained at autopsy from a limited number (n = 11) of human subjects demonstrated a significant negative correlation (r = -0.908, P less than 0.01) between postmortem interval (range 2 to 20 h) and cardiac blood pH.
