The Origin, Location, and Projections of the Embryonic Abdominal Motorneurons ofDrosophila

Abstract

We have used a retrograde labeling technique to identify motorneurons for each of the 30 body wall muscles of an abdominal hemisegment in the late stage 16 Drosophila embryo. Each motorneuron has a characteristic cell body position, dendritic arborization, and axonal projection. In addition, we have determined the neuroblasts of origin for most of the motorneurons we describe. Some organizational principles for the neuromuscular system have become apparent: (1) There is no obvious topographic relationship between the cell body positions of motorneurons and the position or orientation of the muscles they innervate; (2) motorneurons that innervate muscles of similar position and orientation are often clustered and have overlapping dendritic trees; (3) morphologically similar motorneurons are generally derived from a common neuroblast and innervate operationally related muscles; and (4) neuroblasts can give rise to more than one morphological type of motorneuron.

New perspectives on the roles of Abl tyrosine kinase in axon patterning

“…7,9,15,35,38 Intersegmental Nerve b (ISNb) comprises axons from 9 CNS motor neurons that exit the CNS in association with the intersegmental nerve (ISN) and establish synaptic connections with ventrolateral muscles. 59 In Abl gain-of-function or Ena zygotic mutant embryos, the ISNb axons fail to defasciculate from the ISN and do not invade the muscle field but instead continue growing in association with the ISN (termed a "bypass" phenotype) (Fig. 3E).…”

Functional and Genetic Analysis of Spectraplakins in Drosophila

“…A key prerequisite for detecting and working with these phenotypes is the existence of enormously detailed descriptions of all embryonic motor and sensory neurons including their axonal and dendritic morphology (Landgraf, Bossing, Technau, & Bate, 1997;Merritt & Whitington, 1995;Rickert, Kunz, Harris, Whitington, & Technau, 2011). For functional analyses, they can either be stained with antibodies [all neurons (anti-HRP), (subsets of ) sensory (22C10, Mab49C4) or motor axons (anti-FasII, anti-FasIII)] or using GAL4/UAS-based (Chiang et al, 2011) as well as manual single-cell labeling strategies (Hoang & Chiba, 2001;Landgraf et al, 1997). Simple strategies based on anti-HRP-labeled histological landmarks were developed to measure the extent of axon/ nerve growth toward their respective target areas, thus generating quantitative data for mutant or experimental analyses (Bottenberg et al, 2009).…”

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“…All chemicals were obtained from Sigma (St. Louis, MO). Dual intracellular 99 recordings were made at 21 − 23 • C from dorsal acute muscle 1 [31] in abdominal Devices) in bridge mode and digitized at a sampling rate of 10 kHz by Digidata 1320A 106 (Axon Instruments). Recordings were stored using PClamp 8.2 (Molecular Devices) and 107 were imported into Spike2 (Cambridge Electronic Design) for processing.…”

“…The target muscle recorded in these experiments was dorsal acute muscle 1 [31], referred 158 to herein as M1. M1 is innervated by two MNs, MN1-Ib and MNISN-Is [28,29], also 159 referred to in the literature as aCC and RP2, respectively [28,31].…”