Differentiation and central projections of peripheral sensory cells with action-potential block in Drosophila mosaics (original) (raw)
Related papers
The central projections of mesothoracic sensory neurons in wild-type Drosophila and bithorax mutants
Developmental Biology, 1982
Sensory axons entering the CNS from large campaniform sensilla on the normal, mesothoracic wings of four-winged flies of the genotype br3;obz/Ukc'S0follow the same two tracts as do the corresponding axons in wild-type flies. However, they produce more branches along the ventromedial tract (including some in the mesothoracic neuromere), more fibers crossing the midline in the metathorax, and several other modifications of the wild-type pattern. No morphological differences between the receptors in normal and mutant flies could be detected, even with the SEM. The extra branching and other altered characteristics are present in bithoraz flies which are also genetically wingless and do not form the homeotic appendages, so they appear to be due to the b2pbx/Uba? or bx3/UbzP genotype and not to some effect of the axons from the homeotic wings. 99
Eight sensory structures (campaniform sensilla), appearing identical in the light and scanning electron microscopes, are found in specific locations on the wings of Drosophiia. Their axons enter one of 2 central tracts, a medial one or a lateral one. The topographic arrangement of the sensilla on the wing is not reflected in this central projection pattern. There is, however, a strict correlation between the time when a sensillum develops and the path its axon follows: The 4 sensilla whose axons form the medial projection are born and differentiate early during the development of the wing, while the other 4 sensilla, all of which project laterally, arise during a second wave of differentiation.
Experimental analysis of sensory nerve pathways in Drosophila
Dev Genes Evol, 1978
The pathway of adult sensory nerves has been analysed in three experimental situations: (i) in flies with grossly abnormal thoracic morphology resulting from X-irradiation early during development, (ii) in flies which had been subjected to surgical operations late in the larval period, (iii) in homoeotic mutants. The results provide experimental support for a simple mechanism in which developing adult axons join the nearest larval nerve and are guided by it up to the central nervous system. In particular, experimental interference with normal development can result in nerves from different segments, or from dorsal and ventral appendages, joining each other and entering the central nervous system together.
Sensory neurons and peripheral pathways in Drosophila embryos
Roux's Archives of Developmental Biology, 1986
The thoracic and abdominal segments of the Drosophila embryo contain 373 neurons innervating external sensory structures and 162 neurons innervating chordotonal organs. These neurons are arranged in ventral, lateral and dorsal clusters within each segment, in a highly invariant pattern. Two fascicles are formed in each segment as the sensory axons grow ventrally towards the CNS and meet motor axons growing dorsally from the CNS. In all but the last segment, the anterior fascicle is contributed by the dorsal and lateral neurons, while the posterior one is formed by the ventral neurons. Five distinct segmental patterns are described, corresponding to (1) the prothorax, (2) the other two thoracic segments, (3) the first seven abdominal segments, (4) the eighth and (5) the ninth (and possibly the tenth) abdominal segments.
Journal of Visualized Experiments, 2011
Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic development and axonal wiring. Recently the dendritic arborization (DA) sensory neurons of the Drosophila larval peripheral nervous system (PNS) have become powerful genetic models in which to elucidate both general and class-specific mechanisms of neuron differentiation. There are four main DA neuron classes (I-IV) 1. They are named in order of increasing dendrite arbor complexity, and have class-specific differences in the genetic control of their differentiation 2-10. The DA sensory system is a practical model to investigate the molecular mechanisms behind the control of dendritic morphology 11-13 because: 1) it can take advantage of the powerful genetic tools available in the fruit fly, 2) the DA neuron dendrite arbor spreads out in only 2 dimensions beneath an optically clear larval cuticle making it easy to visualize with high resolution in vivo, 3) the class-specific diversity in dendritic morphology facilitates a comparative analysis to find key elements controlling the formation of simple vs. highly branched dendritic trees, and 4) dendritic arbor stereotypical shapes of different DA neurons facilitate morphometric statistical analyses.
The determination of sense organ in Drosophila: Effect of the neurogenic mutations in the embryo
Development
We have examined the early pattern of sensory mother cells in embryos mutant for six different neurogenic loci. Our results show that the neurogenic loci are required to restrict the number of competent cells that will become sensory mother cells, but are not involved in controlling the localization or the position-dependent specification of competent cells. We conclude that these loci are involved in setting up a system of mutual inhibition, which transforms graded differences within the proneural clusters into an all-or-none difference between one cell, which becomes the sense organ progenitor cell, and the other cells, which remain epidermal.
The abdomen of Drosophila: does planar cell polarity orient the neurons of mechanosensory bristles?
Neural Development, 2008
Background: In the adult abdomen of Drosophila, the shafts of mechanosensory bristles point consistently from anterior to posterior. This is an example of planar cell polarity (PCP); some genes responsible for PCP have been identified. Each adult bristle is made by a clone of four cells, including the neuron that innervates it, but little is known as to how far the formation or positions of these cells depends on PCP. The neurons include a single dendrite and an axon; it is not known whether the orientation of these processes is influenced by PCP. We describe the development of the abdominal mechanosensory bristles in detail. The division of the precursor cell gives two daughters, one (pIIa) divides to give rise to the bristle shaft and socket cell and the other (pIIb) generates the neuron, the sheath and the fifth cell. Although the bristles and their associated shaft and socket cells are consistently oriented, the positioning and behaviour of the neuron, the sheath and the fifth cell, as well as the orientation of the axons and the dendritic paths, depend on location. For example, in the anterior zone of the segment, the axons grow posteriorly, while in the posterior zone, they grow anteriorly. Manipulating the PCP genes can reverse bristle orientation, change the path taken by the dendrite and the position of the cell body of the neuron. However, the paths taken by the axon are not affected. PCP genes, such as starry night and dachsous orient the bristles and position the neuronal cell body and affect the shape of the dendrites. However, these PCP genes do not appear to change the paths followed by the sensory axons, which must, therefore, be polarised by other factors.