Nucleotide substitution: C?T. Amino acid replacement: R?W. Mutation is in exon 6.
Mutation of the neural transcript.
Lesion maps to the N-terminal region of shakB transcript P2.4 (FBrf0057903).
Mutation in the neural specific exons.
Nucleotide substitution: C410T. Amino acid replacement: R33W. Mutation is in the first amino acid of the putative mature protein, at the predicted cleavage site of the signal sequence.
C20792645T
C410T
R33W | shakB-PC; R204W | shakB-PD; R49W | shakB-PG; R49W | shakB-PH; R49W | shakB-PI
R33W
Mutation is in the first amino acid of the putative mature protein, at the predicted cleavage site of the signal sequence.
The distribution of synaptic profiles between the premotor axon of the peripherally synapsing interneuron (PAPSI) and the motoneuron axons of the dorsal longitudinal muscles in shakB3 flies appears similar to wild-type flies. The total number of synaptic profiles between the PAPSI and the motoneurons is normal in shakB3 flies. The distribution of synaptic profiles among the individual motoneuron axons is significantly different from wild-type, and the area of contiguity between the motoneuron axons and the PAPSI is much greater than in wild-type flies.
Giant fibre is disconnected from the antennal nerve, as demonstrated by the failure of cobalt to pass from the antennal nerve to the giant fibre. Cobalt can pass from the antennal nerve to other cells other than the giant fibre.
Neural mutation.
The DLMs do not respond to brain shocks and the TTMs respond only occasionally and then with a longer than normal latency.
In heterozygotes the reduction in the anterior-posterior extent of the medial branch of the tergotrochantral muscle motorneuron is evident but less than for homozygotes. Posterior branch, and position of the motorneuron cell body are unaffected.
Flies show a reduced attraction response to sucrose and fructose, an abolition of the attraction response to 0.1M NaCl, and a small increase in tolerance to 0.5M NaCl compared to wild-type. The defect in attraction to sucrose is recessive and is due to a shift in the threshold of detection. The l(1)19Ec8 allele interacts with shakB3; the response to sucrose of shakB3 l(1)19Ec8 flies is comparable to shakB3 homozygotes.
Abnormal electrophysiological phenotype. Homozygous flies exhibit uncoordinated leg movements under ether anaesthesia and do not jump to a light off stimulus. Heterozygotes are fully viable but exhibit some neuronal defects.
Unlike for Df(1)16-3-22 (which deletes Pas) homozygotes do not exhibit abnormal tergotrochanteral muscle motoneuron morphology causing a branch of the medial neurite to cross the midline.
Non-jumper. Heterozygotes with Df(1)16-3-22 display the shakB physiological phenotype.
viable; neurological defect
Thomas.
Lack of response in the DLM and an abnormal response in the TTM is due to defects between the GF and TTM motor neuron and between the GF and DLM motor neuron.
shakB alleles exhibit a complex pattern of complementation.