Projections ofDrosophilamultidendritic neurons in the central nervous system: links with peripheral dendrite morphology

Abstract

Neurons establish diverse dendritic morphologies during development, and a major challenge is to understand how these distinct developmental programs might relate to, and influence, neuronal function. Drosophila dendritic arborization (da) sensory neurons display class-specific dendritic morphology with extensive coverage of the body wall. To begin to build a basis for linking dendrite structure and function in this genetic system, we analyzed da neuron axon projections in embryonic and larval stages. We found that multiple parameters of axon morphology, including dorsoventral position, midline crossing and collateral branching, correlate with dendritic morphological class. We have identified a class-specific medial-lateral layering of axons in the central nervous system formed during embryonic development, which could allow different classes of da neurons to develop differential connectivity to second-order neurons. We have examined the effect of Robo family members on class-specific axon lamination, and have also taken a forward genetic approach to identify new genes involved in axon and dendrite development. For the latter, we screened the third chromosome at high resolution in vivo for mutations that affect class IV da neuron morphology. Several known loci, as well as putative novel mutations, were identified that contribute to sensory dendrite and/or axon patterning. This collection of mutants, together with anatomical data on dendrites and axons, should begin to permit studies of dendrite diversity in a combined developmental and functional context, and also provide a foundation for understanding shared and distinct mechanisms that control axon and dendrite morphology.

Large Neurological Component to Genetic Differences Underlying Biased Sperm Use in Drosophila

“…To identify a line effect, analysis of variance (ANOVA) was used to apply a simple linear model to P1 score and progeny number, similar to the analysis previously described (Chow et al 2010;Clark et al 1999;Grueber et al 2007). The mean of the phenotype (y i ) for females from the ith DGRP line was…”

“…To achieve tissue-specific knockdown of select candidate genes, we generated RNAi females by crossing ppk-GAL4/ TM3, Sb (Grueber et al 2007) females to UAS-RNAi-generating males (Vienna Drosophila RNAi Center; para, line 104775; SK, line 103985; Rab2, line 105358; Rim, line 39384). Control females were generated by crossing females from the same ppk-GAL4/TM3, Sb driver line to the AttP RNAi background line (Vienna Drosophila RNAi Center).…”

“…We tested candidates in these neurons because SPR, the only female gene known to be important for sperm competition, signals through them (Hasemeyer et al 2009;Yang et al 2009). Knockdown was achieved with the ppk-GAL4 driver that is specifically expressed in this subset of neurons (Grueber et al 2007). Knockdown females were compared to controls in a sperm competition experiment identical to the DGRP experiment described above.…”

Polycomb genes interact with the tumor suppressor genes hippo and warts in the maintenance of Drosophila sensory neuron dendrites

“…Each of the class IV neurons (ddaC, v'ada, and vdaB) projects its axons to the same medial position on the innermost FasII-positive fascicle in the CNS, and terminal arborization of each of the class IV neurons is stereotyped (Merritt and Whitington 1995;Schrader and Merritt 2000;Grueber et al 2007). For example, the axonal projection of ddaC terminates on the innermost fascicle and sends ipsilateral branches both anteriorly and posteriorly (Fig.…”

Local and Global Methods of Assessing Thermal Nociception in <em>Drosophila</em> Larvae

“…In Drosophila, it is the class IV dendritic arborization sensory neurons that detect noxious thermal and mechanical stimuli 9 in addition to their recently discovered role as photoreceptors 10 . These neurons, which have been very well studied at the developmental level, arborize over the barrier epidermal sheet and make contacts with nearly all epidermal cells 11,12 . The single axon of each class IV neuron projects into the ventral nerve cord of the central nervous system 11 where they may connect to second-order neurons that project to the brain.…”