22 Facts About Michael Menaker

Michael Menaker, was an American chronobiologist who was Commonwealth Professor of Biology at University of Virginia.

Michael Menaker's research focused on circadian rhythmicity of vertebrates, including contributing to an understanding of light input pathways on extra-retinal photoreceptors of non-mammalian vertebrates, discovering a mammalian mutation for circadian rhythmicity, and locating a circadian oscillator in the pineal gland of bird.

When Michael Menaker joined faculty at University of Texas at Austin in 1962, he transitioned to studying circadian rhythms in the house sparrow and the golden hamster.

Michael Menaker has held academic positions at the University of Texas, University of Oregon, and more recently, at University of Virginia, where he has been the Commonwealth Professor of Biology since 1987.

Michael Menaker served as Chairman of the Biology Department at Virginia from 1987 to 1993.

Michael Menaker has mentored several experts in the field of chronobiology, including Joseph Takahashi, Chair of the Neuroscience Department at University of Texas Southwestern Medical Center; Heidi Hamm, Chair of the Pharmacology Department at Vanderbilt University; and Carl Johnson Professor of Biological Sciences at Vanderbilt University.

Michael Menaker has authored almost 200 papers and maintained grant funding to support his research for over 60 years.

In 1968, Michael Menaker provided evidence for the existence of extra-retinal photoreceptors that were sufficient for photoentrainment by measuring rhythmic locomotor behavior as the output signal of the house sparrows circadian clock.

Michael Menaker demonstrated that photoentrainment could occur in the absence of optic neurons, evidence for the presence of an extra-retinal photoreceptor coupled to the House Sparrow circadian clock.

Michael Menaker tested three possible confounding variables for entrainment: temperature fluctuation, post-enucleation retinal fragments remaining in the eye, and ectoparasites that might transfer light information through their movements in the birds' skin.

Michael Menaker treated sparrows with Dry-Die, an anti-parasitic agent, to eliminate any possible effects of light transferring by ectoparasites.

Since the sparrows did not entrain during tests of temperature fluctuation and the sparrows remained entrained 10 months after enucleation, a point at which any excess of the functional retina would have degraded, Michael Menaker ruled out these possible confounding variables.

Michael Menaker's lab concluded the sparrows were able to entrain to environmental light cues.

Michael Menaker concluded the pineal gland is a driving oscillator within a multi-component system.

In 1988, Martin Ralph and Michael Menaker serendipitously came across a tau mutant male golden hamster in a shipment from their commercial supplier, Charles River Laboratories, that was observed to have a circadian period significantly shorter than what is characteristic of that breed.

That same year, Gianluca Tosini and Michael Menaker determined that hamster retinas cultured in vitro produced a consistent circadian rhythm, as measured by melatonin levels.

In 2000, Michael Menaker collaborated with other scientists in the field to use genetically directed representational difference analysis, a new technique in molecular genetics that allowed them to accomplish this goal.

Michael Menaker discovered another mutant hamster, this time showing a free-running period of 25 hours in conditions of constant darkness.

Michael Menaker's graduate student, Ashli Moore, was a teaching assistant in his colleague's animal behavior course when an undergraduate student insisted on trading in her hamster for one that had a period more closely resembling that of her classmates' hamsters.

Michael Menaker bred this mutant hamster with three different females to produce litters with Mendalian ratios of wild-type and heterozygous mutants.

Michael Menaker subsequently bred homozygous mutants with a free-running period of 28 hours.

Michael Menaker's lab is currently in collaboration with Carla Green's molecular biology lab at University of Texas Southwestern Medical Center to study this mutant hamster line further.