He showed that irregular neural firing rates during the day (regulated by WAKE) promote arousal while regular firing patterns during the night promote sleep.

Ben Bell followed up his talk by taking their findings in flies to mammals, describing a mammalian ortholog to the fly WAKE protein (called mWAKE). mWAKE is highly enriched in the master clock, the suprachiasmatic nucleus (SCN) suggesting it plays a role in circadian time keeping or regulation.

Unlike in flies, knockout of mWAKE in mice only caused mild problems in sleep/wake states. However, through measuring locomotor activity, the researchers found that these mice were extremely hyperactive (>5 times more active than wild-type mice). Curiously, this trait (phenotype) only came about during the dark phase (mice are nocturnal, so active during the dark phase). To investigate this further, the researchers examined the firing rates of SCN neurons during the day and night. Normal mice have a large difference between the night and day in SCN firing rates, with peak neural activity occurring during the day. However, mWAKE knockout mice showed no difference between day and night, with firing rates remaining high all the time!

Additionally, cells lacking mWAKE showed blunted responses to the inhibitory neurotransmitter GABA, and this lack of inhibition may explain the hyperactive profile mice lacking mWAKE had. Finally, they examined (using an mWAKE reporter mouse) where mWAKE expressing cells project to throughout the brain. They found that cell bodies were distributed throughout the brain, in all major arousal centers. Importantly, they seemed to be discrete from other neuromodulator systems present in these areas, like hypocretin/orexin neurons in the lateral hypothalamus, or histamine neurons in the tuberomammillary nucleus.

Significant more research is required to fully understand the role this protein plays in sleep/wake states. Is it a ‘master regulator’ of arousal? Does it interact with every ‘arousal center’ differently or does it have a distributed ‘homogenous’ effect across the brain. When does mWAKE start to express during development? Does this coincide with changes to sleep-wake behavior during early age? I’m excited to follow this story going forward!



Expansion Microscopy - ‘Just add Water’

Microscopes are getting beefier and beefier, more complex and expensive, with the sole purpose of being able to see tiny, tiny things just a little bit better. Enter ‘expansion microscopy’, an idea that literally works in the opposite direction to that goal. Instead of ‘zooming in closer’, expansion microscopy aims to ‘blow things up’ in order to see the (once) tiny details (like synapses, or nuclear pores…) on a conventional microscope. Remember those dinosaurs that would expand when you added water as a kid? I sure do…and expansion microscopy works pretty much the same.

Although this technology has been around for a few years, it is just getting started in terms of its ease of use, applicability to different samples (proteins, RNA, DNA, lipids…), and support community. All info on this fascinating technique is available at ExpansionMicroscopy.org.

First described by Edward Boyden and colleagues at the MIT Media Lab in 2015, expansion microscopy is rapidly being applied across fields, species, and disciplines to examine extremely fine structures at the nanoscale (10-20 nm).