Homozygous eag1 significantly blocks or reduces tolerance to both benzyl alcohol and ethanol.
eag1 flies do not show a significantly shortened lifespan. At day 33, the brains of these flies show intermittent pathology.
At room temperature, the motor axon terminals of eag1 larvae show a similar level of arborization to wild-type larvae.
eag1 flies show normal osmotic stress sensitivity on food medium containing NaCl.
The seizure threshold following short wavetrains of high-frequency electrical stimuli (0.5ms pulses at 200Hz for 300ms) is increased in mutant flies (62.1 +/- 10.3 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 resting potentials of mutant dorsolongitudinal muscles does not differ significantly from wild type at 22 or 12oC.
When exposed to 10mM paraquat for 48hr, mutants show 48% survival (wild type shows 97% survival).
Mutant larvae show a reduction in heart rate.
Homozygous adults show a reduced response to propionic acid, ethyl butyrate, 2-butanone and ethyl acetate in an electroantennogram assay compared to control flies. The response to butanol, 1-octanol, benzaldehyde, butyl acetate and 2-heptanone in this assay is not significantly different from the response of control flies to these odorants. Mutant flies have fewer antennal neurons that are sensitive to ethyl butyrate than control flies. The proportion of antennal olfactory neurons that are responsive to membrane-permeant cyclic nucleotide analogues (8-Br-cAMP and 8-Br-cGMP) is also reduced in mutant flies compared to wild-type.
The rate of habituation of the giant fiber escape pathway is increased and the number of stimuli needed to attain five consecutive failures is decreased in eag1 flies compared to wild-type. The short-latency response of the dorsal longitudinal muscle occurs earlier than in wild-type flies. The rate of habituation in Sh21 eag1 double mutants is no more extreme than in Sh21 or eag1 single mutants.
Homozygous adults are more sensitive to paraquat than control flies. Homozygous adults have a reduced lifespan compared to wild-type flies.
eag1/Sh7 double mutants cause an increase in neuronal excitability and result in a postembryonic increase in structure (both number of boutons and branches) at the larval neuromuscular junction (NMJ). Bursting pattern of motor neuron action potentials controlling larval locomotion shows near constant activity. Excitatory postsynaptic potentials (EPSP) reveal defective nerve repolarisation. Number of boutons in eag1/Sh7 double mutants is increased compared to wild type due to reduction in Fas2 expression. Bouton number does not increase when Fas2Scer\UAS.cLa is expressed from Scer\GAL4E62-2 in eag1/Sh7 larvae.
Homozygotes show increased sensitivity to chloroform and trichloroethylene in an inebriometer assay (an assay of geotactic and postural behaviour) compared to wild-type flies. Sensitivity of homozygotes to halothane is not significantly different to wild-type flies, but heterozygotes show slight resistance to halothane compared to wild-type.
Hemizygotes fail to show courtship conditioning, showing an increase in courtship of mated females compared to wild type controls. Physiological studies reveal supernumerary synaptic discharges.
Individuals exhibit clear free-running locomotor activity rhythms.
Mutation dramatically increases the number of excitatory junction potentials (EJP) at the larval neuromuscular junction (NMJ) (FBrf0039808). eag1 Sh14 double mutant embryos show greatly increased synaptic activity, both the burst frequency and the mean excitatory junction current (EJC) amplitude are increased during synaptogenesis. The synaptic morphology of the double mutant embryonic NMJs raised at the restrictive temperature are not significantly different from wild type, at the light microscope level. These hyperactive synapses expand to occupy a larger area of the muscle surface relative to wild type causing decreased synaptic density (the branch and bouton numbers are not altered).
eag1 Sh21 double hemizygous bristle sensory cells in small-patch mosaic adult flies are more responsive to tactile stimulation than wild-type bristles, although the pathfinding and formation of sensory cell projections is normal.
eag1, Sh14 double mutants have normal grooming behavior.
Response of the channel to modulation by protein kinases depends on temperature: IA is increased at 5oC but remains almost unchanged at 16oC, conversely IK is nearly normal at 5oC and decreased at 16oC. At 16oC IA and IK levels, and ICF and ICS levels can be reduced by application of W7, a Ca2+/CaM antagonist. cGMP-modulation of IK and IA by the mutant channel by 8-Br-cGMP is altered.
Flies show some leg-shaking under anaesthesia. The action potential of the dorsal longitudinal muscle often appears abnormal in Sh14 eag1 double mutants. The action potential of the dorsal longitudinal muscle occasionally appears abnormal in eag1 mutants. Lowers the following frequency of the giant fibre response of the tergotrochanteral muscle pathway. eag1 Sh21 and eag1 Sh14 double mutant flies show spontaneous activity of the dorsal longitudinal and dorsoventral indirect flight muscles when at rest. This phenotype is suppressed by mlenap-ts1 in eag1 Sh21 mlenap-ts1 flies. 86% of eag1 Sh14 flies have a wings-down phenotype.
No effect on synaptic currents at neuromuscular junction of third instar larvae.
The mutants effects can be potentiated by mutations in dnc and the enhancement can be counterbalanced by rut1. The effect of extreme hyperexcitability in eag Sh double mutants cannot be potentiated by mutations in dnc.
Defects in all K+ currents within larval muscle.
Recessive mutation. eag1 Sh14 double mutant larvae show an increased number of tertiary and quarternary axonal branches over muscles 12 and 13. The number, and in some cases density, of varicosities in the neurites is also increased. eag1 Hk1 double mutant larvae have a similar phenotype. eag1 Hk1 double mutant larval muscles show periods of activity not organised into bursts (tonic activity) in contrast to wild-type.
eag1 males show conditioned courtship behaviour like wild-type males, but the refractory period is abnormally short.
Homozygous flies have a high frequency of spontaneous excitatory junction potentials (ejps). eag1 interacts synergistically with either Sh14 or Sh21 in double mutants to produce extremely prolonged neuromuscular transmission and spontaneous firing of the motor axons. eag1 larvae treated with 4-aminopyridine show a striking enhancement of the amplitude and duration of the ejp, and they also show spontaneous ejps.
Abnormal leg shaking under ether anaesthesia; aberrant, repetitive firing of action potentials in larval nerves; potassium currents abnormal in larval muscles (Wu, Ganetzky, Haugland and Lin, 1983). eag Sh double mutants display greatly increased level of spontaneous neuronal activity and extreme behavioral phenotypes (Burg and Wu, 1989).