At 24-28hrs after egg laying, dendrites of the dorsal class IV neuron (ddaC) in homozygous Nmnat^Δ4790-2 mutants do not show any patterning defects and are largely indistinguishable from those of wild-type controls. Although heterozygosity for Nmnat^Δ4790-2 has no effect on dendritic outgrowth or branching of ddaC at 48 hours after egg laying, there is a significant reduction in the total number of terminal dendritic branches and total dendrite length at 120 hours after egg laying. At 72 hours after egg laying, Nmnat^Δ4790-2 heterozygotes tend to have fewer terminal dendrites, although the average number of terminal dendritic branches is not significantly different from wild-type controls until after 72 hours after egg laying.

The axons of class IV neurons in Nmnat^Δ4790-2 heterozygotes are largely intact at 120 hours after egg laying. Axons enter the CNS appropriately and their projection patterns in the ventral nerve cord (VNC) are morphologically indistinguishable from wild-type controls.

Whereas wild-type ddaC clones elaborate highly branched dendrites, Nmnat^Δ4790-2 clones show a significant reduction in the total number of terminal dendritic branches, effectively reducing dendritic field coverage. There is no evidence of severed or degenerated dendrites in Nmnat^Δ4790-2 clones as dendritic trunks and branches are largely intact.

Class III neurons, that normally elaborate actin-rich protrusions along their dendrites, are largely devoid of terminal branches in Nmnat^Δ4790-2 clones. Class I neurons, which normally elaborate few terminal branches that cover a small receptive field, exhibit a minor, but statistically significant decrease in the total number of dendritic branches in Nmnat^Δ4790-2 clones.

Although class IV neurons do not exhibit an axon degeneration phenotype in Nmnat^Δ4790-2 heterozygotes, approximately 96% of homozygous Nmnat^Δ4790-2 sensory neuron clones show extensive fragmentation of axons and a near complete loss of axon terminals in the ventral nerve cord.

Different subtypes of motor neurons display both terminal and dendritic branching defects and extensive beading and fragmentation at 120 hours after egg laying in Nmnat^Δ4790-2 MARCM clones. The axon terminals of Nmnat^Δ4790-2 motor neuron clones are absent in the majority of neurons. Phenotypes are progressive, getting worse with age, as axons and dendrites of Nmnat^Δ4790-2 motor neuron clones are largely intact at 72 hours after egg laying.

Flies with eyes that contain Nmnat^Δ4790-2 clones show reduced depolarization and on/off responses in electroretinogram (ERG) recordings and show photoreceptor synaptic defects.

Nmnat^Δ4790-2 is a suppressor of larval multidendritic class IV neuron phenotype of wts^x1

Nmnat^Δ4790-2 is a suppressor of dendrite phenotype of wts^x1