Arnold Eskin
   HOME

TheInfoList



OR:

Arnold Eskin was a professor of
chronobiology Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobi ...
at the
University of Houston The University of Houston (UH) is a Public university, public research university in Houston, Texas. Founded in 1927, UH is a member of the University of Houston System and the List of universities in Texas by enrollment, university in Texas ...
in
Houston, Texas Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 in ...
. He attended
Vanderbilt University Vanderbilt University (informally Vandy or VU) is a private research university in Nashville, Tennessee. Founded in 1873, it was named in honor of shipping and rail magnate Cornelius Vanderbilt, who provided the school its initial $1-million ...
, where he received a degree in physics. He later attended
University of Texas at Austin The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,075 ...
, where he received his Ph.D. in
zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...
in 1969. He is recognized in the term Eskinogram, and has been a leader in the discovery of mechanisms underlying entrainment of circadian clocks.


Research


Menaker lab

In his early scientific career, Eskin studied circadian rhythms in the
house sparrow The house sparrow (''Passer domesticus'') is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pale brown and grey, a ...
, while working in chronobiologist Michael Menaker's lab at the University of Texas at Austin. Eskin's most cited paper while in Menaker's lab concerns his research of non-ocular entraining cues in house sparrows. In it, Eskin and Menaker showed the scientific community the ability of house sparrows to entrain to auditory cues as opposed to previously shown light cues.


Ongoing research

Eskin's current research focuses on
long-term memory Long-term memory (LTM) is the stage of the Atkinson–Shiffrin memory model in which informative knowledge is held indefinitely. It is defined in contrast to short-term and working memory, which persist for only about 18 to 30 seconds. Long-t ...
formation. His lab focuses on the role of the
circadian clock A circadian clock, or circadian oscillator, is a biochemical oscillator that cycles with a stable phase (waves), phase and is synchronized with solar time. Such a clock's ''in vivo'' period is necessarily almost exactly 24 hours (the earth's curre ...
and the regulation of
glutamate Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can syn ...
uptake in synaptic plasticity, using aplysia and
rats Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' (pack rats), ''Bandicota'' (bandicoot ...
as model organisms primarily.


Role of glutamate transporters in memory formation

Eskin's lab has extensively studied the role of
glutamate Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can syn ...
transporters in synaptic plasticity in aplysia. Specifically, his group has shown that glutamate uptake increases during long-term sensitization in Aplysia, long-term potentiation (LTP) in the
hippocampus The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, a ...
of rats, and morphine addiction and withdrawal in rats. Deficiencies in glutamate uptake during changes in synaptic efficacy have also been linked to diseases such as
Amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...
(ALS),
Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
, and
Epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...
. Blockage of
NMDA receptors The ''N''-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA rece ...
prevents glutamate from binding, which prevents the formation of long-term memory. Eskin's group believes that the mechanism for glutamate uptake is phylogenetically conserved for multiple types of synaptic plasticity. They currently study the mechanism by which this process takes place.


Role of circadian clocks in memory formation

Eskin has also researched the role of the circadian clock in glutaminergic synaptic plasticity. Although it was known that the brain's circadian clock could influence physiological outputs such as sleep and wakefulness, metabolic rate, and body temperature, Eskin suggested that the circadian clock may play another role as a regulator for memory formation. He and his lab have shown that an aplysia's ability to form long-term memory is dependent on the time of day, namely that aplysia are able to form long-term memories during the day, but are unable to at night. This was done via regulation of several factors, including
neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neuro ...
release, MAPK signaling, and immediate early gene expression.
Short-term memory Short-term memory (or "primary" or "active memory") is the capacity for holding a small amount of information in an active, readily available state for a short interval. For example, short-term memory holds a phone number that has just been recit ...
, however, has not been shown to vary based on time of day. The mechanism by which this occurs is not currently understood, but Eskin and his lab have continued to study the circadian characteristics of glutamate uptake in synaptic plasticity in order to learn more about the mechanism by which memory formation is controlled by a circadian clock. Furthermore, such information will be useful for chronobiology as a whole in helping explain how a biological clock regulates its outputs to produce rhythm.


Eskinogram

Eskin developed the Eskinogram as a
heuristic A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, ...
that provides a mechanism for understanding circadian clock pathways. It presents a clock pathway as having three components: input, oscillator, and output. Further modifications to this core model can be made for more complex systems. For example, one oscillator may be able to control multiple outputs.


Model use

The Eskinogram has notably been used to model how the
suprachiasmatic nucleus The suprachiasmatic nucleus or nuclei (SCN) is a tiny region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regula ...
(SCN) acts as a master oscillator for the human biological clock. A group of photoreceptors called the intrinsically photosensitive retinal ganglion cells (ipRGCs) act as the input for the clock mechanism. These cells then use a pathway dependent on
melanopsin Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene ''Opn4''. In the mammalian retina, there are two additional categories of opsins, both involved in the for ...
to signal to the SCN. The SCN then uses a transcription-translation feedback loop, consisting of a set of clock genes that regulate their own expression, to act as a complete oscillator and signal locomotor outputs accordingly.


Impact

The Eskinogram is regarded as a
central dogma The central dogma of molecular biology is an explanation of the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein", although this is not its original meaning. It was first stated by ...
for circadian researchers. This has led to Eskin's work being influential to later researchers in chronobiology. For example, Eskin worked closely with Dr. Samer Hattar on his thesis on circadian rhythms.


Awards and honors

For his contributions to the Department of Biology and Biochemistry, Eskin received the 25th Esther Farfel Award from the University of Houston in 2003. Serving as department chair from 1994 to 2000, he established a focus on research in neuroscience, biological clocks, and infectious disease and tripled research grants to the department. In the same year, Eskin also received the John and Rebecca Moores Professors Award from the University of Houston."Biologist gets two top honors." ''The Daily Cougar'

Retrieved 2015-04-07.


References

{{DEFAULTSORT:Eskin, Arnold University of Houston faculty University of Texas at Austin College of Natural Sciences alumni Vanderbilt University alumni Chronobiologists 21st-century American biologists