Samer Hattar ( ar, سامر حتر) is a chronobiologist and a leader in the field of non-image forming photoreception. He is the Chief of the Section on Light and Circadian Rhythms at the

National Institute of Mental Health The National Institute of Mental Health (NIMH) is one of 27 institutes and centers that make up the National Institutes of Health (NIH). The NIH, in turn, is an agency of the United States Department of Health and Human Services and is the prima ...

, part of the

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...

. He was previously an associate professor in the Department of Neuroscience and the Department of Biology at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...

in Baltimore, MD. He is best known for his investigation into the role of

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 ...

and

intrinsically photosensitive retinal ganglion cells Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye. The presence ...

(ipRGC) in the

entrainment Entrainment may refer to: * Air entrainment, the intentional creation of tiny air bubbles in concrete * Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency * Entrainment (biomusicology), the synchronization o ...

circadian rhythms A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to ...

Life

Samer Hattar was born in

Amman Amman (; ar, عَمَّان, ' ; Ammonite language, Ammonite: 𐤓𐤁𐤕 𐤏𐤌𐤍 ''Rabat ʻAmān'') is the capital and largest city of Jordan, and the country's economic, political, and cultural center. With a population of 4,061,150 a ...

Jordan Jordan ( ar, الأردن; tr. ' ), officially the Hashemite Kingdom of Jordan,; tr. ' is a country in Western Asia. It is situated at the crossroads of Asia, Africa, and Europe, within the Levant region, on the East Bank of the Jordan Rive ...

to a Jordanian father and a Lebanese mother. Raised in a

Christian Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρι ...

family, he planned on becoming a

priest A priest is a religious leader authorized to perform the sacred rituals of a religion, especially as a mediatory agent between humans and one or more deities. They also have the authority or power to administer religious rites; in particu ...

. He studied at Terra Sancta High School, a Catholic high school in Amman, from 1978 to 1988. He earned good grades in his classes and fell in love with biology when introduced to Mendel's pea plant experiments. This passion inspired him to pursue a career in science. He attended

Yarmouk University Yarmouk University ( ar, جامعة اليرموك), also abbreviated YU, is a comprehensive public and state supported university located near the city centre of Irbid in northern Jordan. Since its establishment in 1976, Yarmouk University (YU) ...

in Irbid for his undergraduate studies, where he majored in Biology and minored in Chemistry. His high marks earned him the honor of meeting Hassan Bin Talal, the prince of Jordan. After graduating from Yarmouk in 1991, he completed a master's degree in biochemistry at the

American University of Beirut The American University of Beirut (AUB) ( ar, الجامعة الأميركية في بيروت) is a private, non-sectarian, and independent university chartered in New York with its campus in Beirut, Lebanon. AUB is governed by a private, aut ...

Beirut Beirut, french: Beyrouth is the capital and largest city of Lebanon. , Greater Beirut has a population of 2.5 million, which makes it the third-largest city in the Levant region. The city is situated on a peninsula at the midpoint o ...

. He began his graduate studies in biochemistry in 1993 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 ...

where he studied circadian regulation of a

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...

aplysia ''Aplysia'' () is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are one clade of large sea slugs, marine gastropod mollusks. These benthic herbivorous creatures can become rather large compared with most ...

. Hattar completed his postdoctoral fellowship at the Solomon Snyder Department of Neuroscience at

Johns Hopkins University School of Medicine The Johns Hopkins University School of Medicine (JHUSOM) is the medical school of Johns Hopkins University, a private research university in Baltimore, Maryland. Founded in 1893, the School of Medicine shares a campus with the Johns Hopkins Hospi ...

, where he made discoveries on ipRGCs. In 2004, he established his laboratory in the Department of Biology at

. He is married to Rejji Kuruvilla, a neuroscientist also working at Johns Hopkins.

Scientific work

Hattar is known for his work in the area of chronobiology. He is credited with discovering that the

photopigment Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and p ...

melanopsin and associated ipRGCs play an important role in the entrainment of circadian rhythms Before Hattar's work, it was assumed that organisms entrained to daily light-dark cycles through the same mechanisms that are responsible for vision. However, case studies reported that some who were completely blind could still entrain to these cycles. This observation, coupled with the discovery of melanopsin by

Ignacio Provencio Ignacio Provencio (born 29 June 1965) is an American neuroscientist and the discoverer of melanopsin, an opsin found in specialized photosensitive ganglion cells of the mammalian retina. Provencio served as the program committee chair of the Societ ...

, led Hattar to hypothesize that this photopigment might be responsible for photoentrainment.

Awards and honors

* Albert Lehninger Research Award, 2004 * Alfred P. Sloan Research Fellow, 2006 * Lucile & David Packard Foundation Fellowship for Science and Engineering, 2006

References

External links

JHU Biology Department: Dr. Hattar's page
{{DEFAULTSORT:Hattar, Samer Year of birth missing (living people) Living people Jordanian biologists Chronobiologists Yarmouk University alumni American University of Beirut alumni University of Houston alumni Johns Hopkins University faculty