Sh5 homozygous adults exhibit locomotion defects, including increased movement time spent in the centre of a circular space (instead of movement mostly along the edges) and significantly increased velocities of head and hind-leg movements under ether anesthesia (the leg movements are continuous and do not stop immediately after severance from the body), as compared to controls.
Sh5 mutant flies display largely normal flight parameters, with wing beat frequency, DLM firing rate, and inter-spike-interval CV not differing significantly from wild-type.
Mutant flies exhibit a decrease in the daily sleep amount. This is mainly due to a decrease in the duration of sleep episodes rather than in their number. This phenotype is very sensitive to background modifiers.
The seizure threshold following short wavetrains of high-frequency electrical stimuli (0.5ms pulses at 200Hz for 300ms) is slightly increased in mutant flies (51.3 +/- 6.1 V) compared to controls.
The threshold for activation of the giant fiber in mutant animals following single stimulus pulses (0.2ms duration, 0.5Hz) is not significantly different from that of wild type.
The giant fiber following frequency (the maximum stimulation frequency that the giant fiber pathway can reliably follow) is reduced compared to wild type in mutant animals.
When exposed to 10mM paraquat for 48hr, mutants show 30% survival (wild type shows 97% survival).
Sh5 flies treated with sodium valproate (NaVP) do not show a reduction in body weight, in contrast to wild-type flies. Sh5 heterozygotes also show an increase in resistance to lethality caused by NaVP compared to wild type. Sh5 flies treated with phenytoin sodium show an increase in body weight, as is seen in wild-type flies.
Habituation of the giant fiber escape pathway occurs more rapidly in Sh5 flies than in wild-type. The long-latency response is delayed slightly. The short-latency response of the tergotrochanteral muscle is delayed. Habituation in Hk1 Sh5 double mutants is markedly retarded, as in Hk1 single mutants, rather than more rapid as in Sh5 single mutants.
Hemizygous males exhibit an anesthesia-induced leg shaking phenotype, females appear wild type.
Homozygous adults are more sensitive to paraquat than control flies. Homozygous adults have a reduced lifespan compared to wild-type flies.
The life expectancy of Sh5 hemizygous males is shortened, as compared to controls.
Application of serotonin failed to alter modulation of the potassium channel in a semi-intact preparation of the retina.
Homozygotes show increased sensitivity to chloroform and trichloroethylene, but not to halothane in an inebriometer assay (an assay of geotactic and postural behaviour) compared to wild-type flies.
Mutant flies show a shortened life span due to a normal, but accelerated, course of aging at 18oC and 25oC.
Two-electrode voltage clamp technique is used to measure end-plate currents in larval neuromuscular junctions. Currents are four fold larger than wild type, lack post-tetanic potentiation (PTP) but could undergo facilitation. PTPs could be restored by addition of Cd2+.
Vibration of appendages in spaced bursts. Double mutant combinations with tta1 show slight suppression of the Sh phenotype. Sh phenotype is enhanced by the presence of one extra copy of tta.
eag4PM Sh5 double mutant flies do not show spontaneous activity of the dorsal longitudinal and dorsoventral indirect flight muscles when at rest.
Heterozygotes show ether induced leg shaking. Hemizygous males show a reduced preference for sucrose compared to wild-type in feeding preference tests, probably due to a shift in the threshold of detection. Flies show an enhanced attraction to 100mM NaCl and an increased tolerance to 0.5M NaCl and 0.2M KCl compared to wild-type. The increased tolerance to 0.5M NaCl and 0.2M KCl is due to an increase in the threshold of repulsion. The firing patterns of the labellar chemosensory neurons in response to sucrose, NaCl and KCl are normal.
The depolarisation of the Sh5 current steady-state inactivation curve is enhanced compared to wild-type in cells from the thoracic ganglia of very late stage pupae.
Flies manifest chronic vibration of their appendages as well as abnormal action potentials.
The I-V relation and kinetics of IA are altered in homozygous third larval instar muscles, probably indicating altered properties of the IA channel. IA is much lower than predicted by simple gene-dosage dependence in Sh5/Sh14 or Sh5/Sh7 flies.
The voltage required to activate and inactivate the A1 channel is increased by approximately 20mV, and the steepness of the voltage dependence of steady-state inactivation is decreased in cultured embryonic Sh5 myotubes.
A-type current is altered but not abolished.
Sh5 males show no conditioning of courtship behaviour. Sh5 mlenap-ts1 double mutant males or Sh5 males treated with tetrodotoxin are essentially normal in their acquisition of conditioned courtship behaviour, but are defective in retention of the conditioned response.
Ether-dependent leg shaking and wing scissoring. Chloroform, ethyl acetate and carbon dioxide etherization does not elicit shaking behavior, though nitrogen and triethylkamine etherization does. Unetherized, older flies show uncoordinated walking behavior, and stand quivering on the bottom of the culture bottle.
Hemizygous males show a 18% reduction in lifespan. Heterozygous females show only a slight reduction in lifespan.
abnormal leg shaking under ether anesthesia; abnormal A-type potassium currents in larval muscle and/or pupal flight muscle; abnormal action potentials in the adult cervical giant fiber; abnormal synaptic transmission at the larval neuromuscular junction and multiple firing of larval motoneurons.