摘要:

This report contains additional observations on the cell lineage relationships of the motor neurons of the facial nucleus and of the cerebellar Purkinje cells of the mouse. These cell populations were quantitatively analyzed in the mosaic brains of experimental aggregation chimeras. The cell markers used to perform the analysis were (1) staining differences inβ-glucuronidase enzyme activity due to differences at theGuslocus on chromosome 5 and (2) self-destruction of all Purkinje cells of one genotype due to the cell autonomous action of the lurcher gene on chromosome 6. Of 6 animals examined in the Purkinje cell study, 5 showed left/right differences in the clonal composition of the cerebellum. Of 4 animals examined in the facial nucleus study, all 4 showed differences in genotype ratio. These results imply that the event that defines the selection of the progenitor cells for each of these two cell types is, in fact, two bilaterally independent events. This is consistent with the pictures of the early nervous system derived from embryo-logical observations. The implication of these findings for cell mixing during development is discussed.

ISSN:0167-7063    

DOI:10.3109/01677068409107092

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Temperature-sensitive mutations of the choline acetyltransferase(Cha)gene, which lead to reduced choline acetyltransferase (ChAT) activity and acetylcholine (ACh) levels3,22, have been used in an attempt to identify the neurotransmitter at a chemical synapse in the giant fiber pathway (GFP) ofDrosophila melanogaster.Prolonged incubation of adult mutant flies at non-permissive temperatures blocked the response of this pathway to brain stimulation, whereas shorter incubation times disturbed various parameters of the normal response. Even at permissive temperature subnormal responses were still evident. These defects in the giant fiber pathway's function suggest a specific cholinergic synapse within the pathway, the first synapse of this type implicated inDrosophila.When the function of this synapse was experimentally stressed, disruptions of GFP function paralleling decreased ChAT activity began to appear at enzyme levels estimated to be approximately 80% of wild-type.

ISSN:0167-7063    

DOI:10.3109/01677068409107093

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Six zygotically expressed genomic lociof Drosophila melanogaster, N, bib, mam, neu, DlandE (spl), have previously been found to be involved in the commitment of ectodermal cells as neuroblasts. We have studied phenotypes induced by various mutant alleles at these 6 loci in imaginal epidermal cells, in order to assess possible implications of the genes in functions other than early neurogenesis. When homozygous, any of these mutations exceptbibaffected the development of bristles and compound eye in various ways. These range from cell death to the production of additional bristles and several defects in ommatidial patterning, depending on the allele used. In contrast clones ofbibhomozygous cells exhibited wild-type phenotypes. The differences found in the expression of the neurogenic genes are discussed with respect to a hypothesis on the genetic control of neurogenesis.

ISSN:0167-7063    

DOI:10.3109/01677068409107094

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Neuronal membrane channels ofDrosophila melanogasterwere altered either genetically or pharmacologically in order to investigate the role of specific ionic currents in the acquisition and retention of a conditioned behavior. Conditioning could not be detected forShakermutants, in which the fast transient potassium current (IA) is altered; a second potassium channel mutant,eag(ether a go-go) is conditioned like wild type, but the retention period is abnormally short. Thenaptsmutant (no action potential, temperature sensitive), in which nerve excitability is reduced, also expresses normal acquisition and a shortened period of retention. Double mutants ofSh5andnaptsas well asSh5treated with tetrodotoxin, are essentially normal with respect to acquisition; in both cases these flies remain retention-defective. These experiments therefore reveal a behavioral phenotype ofDrosophilamutants in which the primary physiological defect seems to be in the functioning of specific neuronal ionic channels.

ISSN:0167-7063    

DOI:10.3109/01677068409107095

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor