mGluR112b mutants have an altered daily sleep profile, with: increased sleep during daytime and reduced sleep during nighttime; increased sleep bout number, but not duration, during daytime and decreased number of longer (>15min) sleep bouts during nighttime; increased number and decreased duration of wake bouts only during daytime, and decreased duration of wake bouts during nighttime. However, there are no significant changes in: total daily sleep amounts, waking activity or climbing ability (negative geotaxis) when compared to wild-type controls.
In mGluR112b mutants, after multiple days under constant darkness, the sleep and wake rhythms, the sleep amount during the subjective day and night, as well as sleep and wake bouts become similar to those in controls. Some of these changes are already observed after 2 days in constant dark.
At one month of age, mGluR112b mutants exhibit increased sleep, higher sleep bouts with no change in average length of sleep bouts, and more wake bouts with decreased wake bout length during day time while at night, they exhibit decreased sleep, reduced sleep bout length with a reduction in number of sleep bouts and fewer wake bouts with increased bout length when compared to aged controls. Also they show reduced total daily sleep amount when compared to aged controls.
mGluR112b mutant flies are deficient in olfactory short term memory compare to controls.
mGluR112b/mGluR112b mutant males between 6-10 days post-eclosion have significantly impaired courtship behavior, exhibiting almost no courtship activity, as compared with mGluR2b/mGluR2b controls, and are defective in progressing through the phases of courtship, but do not display any gross defects in locomotor behavior, olfaction or vision, as compared to wild type.
mGluR112b/+ mutant males exhibit significantly impaired courtship behavior; and impaired learning-during-training, immediate-recall memory, short-term memory or long-term memory in conditioned courtship assays, but no significant defects in progressing through the phases of courtship, and do not display any gross defects in locomotor behavior, olfaction or vision, as compared to wild type.
Boutons in mGluRA112b mutants often appear to be larger in size than wild-type.
mGluRA112b mutants exhibit neuronal hyper-excitability and demonstrate an increase rate of onset of long term facilitation.
mGluR112b/+ 30-day-old adult males display learning defects (fail to demonstrate the typical decrease in courtship activity when paired with an mated unreceptive female) as well as the loss of short-term (60 min) memory.
mGluRA112b mutants show a tendency towards elevated response amplification compared to controls. However, there are no statistically significant differences in EJC amplitude between mGluRA112b and controls.
mGluRA112b mutants show comparable levels of short-term facilitation as wild-type controls.
During prolonged 10-Hz stimulation, mGluRA112b mutants exhibit a large increase in mean normalised response amplitude during the entire period of prolonged high-frequency stimulation (HFS). During early HFS (<10s), mGluRA112b mutants quickly reach their augmentation peak amplitude.
mGluRA112b mutants exhibit a striking hyperpotentiation response amplitude. This is transient, persisting on average for 30 seconds following HFS.
mGluRA112b mutants show premature LTF, manifested as a sudden increase in EJC response amplitude during HFS.The transition between the modestly elevated augmentation level and the dramatically elevated LTF level is very sharp, usually occurring in a single jump between two adjacent stimiuli. This change is always unidirectional to the hyper-facilitated level, which persists for the length of the HFS and beyond.
Loss of mGluR through a mGluR112b null mutant background strongly impairs coordinated movement behavior, with the average response time in a roll-over assay lengthened by 48%. In individual animals, the behavioral defect is clearly evident as a combination of inappropriate movement responses and defects in cooperative motor control. These mutants appear to 'struggle' during a period of continuous spastic muscle contraction. mGluR112b mutant larvae display a very significantly slowed performance compared to wild-type.
mGluR112b mutants display no defects in neuromuscular junction synaptic branching, compared to wild-type.
mGluR112b mutants display a slight, but not quite significant decrease in synaptic area compared to controls.
mGluR112b mutants display a small decrease in the number of synaptic boutons in the neuromuscular junction.
At the ultrastructural level, the overall appearance of a bouton and the postsynaptic subsynaptic reticulum in mGluR112b mutants appears normal. Quantitatively, there is no significant difference in bouton size, mitochondria size, active zone size/number or the postsynaptic subsynaptic reticulum between mGluR112b mutants and control larvae.
The functional properties of glutamergic neuromuscular junctions from mGluRA112b wandering third instar larvae show no changes in basal synaptic transmission compared to controls. Also, the response patterns of synapses in the presence of 1.8mM Ca2+ is undistinguishable between mutants and controls. Action potential propagation in motor nerves appears unaffected in mGluRA112b larvae.
Using a stimulation frequency of 10 Hz, the level of facilitation during short stimulus trains is increased approximately threefold on average in mGluRA112b larval neuromuscular junctions compared with controls. During prolonged stimulation at 5 Hz, the response pattern dramatically changes in mGluRA112b mutants showing a step-like, 10-fold increase in EJC amplitude that is accompanied by pronounced asynchrony of the response. After stimulation, synaptic responses remain strongly potentiated in mutants before they suddenly revert to a normal level of sustained posttetanic potentiation. mGluRA112b/Df(4)O2 larvae also show this phenotype.
Third star mutant mGluRA112b/Df(4)O2 and neuromuscular junctions show a significant reduction in the number of type I synaptic boutons compared to controls. The mutant Ib boutons are larger in size than in controls, although the total area covered by the boutons is the same as in controls, indicating a compensation of the defect in bouton number by an increase in size. mGluRA112b/+ larvae do not show defects in bouton number or size.