Samer Hattar () is a

chronobiologist Chronobiology is a field of biology that examines Time, timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to sun, solar- and moon, lunar-related rhythms. These cycles are known as biological ...

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 primar ...

, part of the

National Institutes of Health The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Service ...

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

Johns Hopkins University The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

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 retinylidene protein, retinal proteins called opsins and encoded by the gene ''Opn4''. In the mammalian retina, there are two additional categories of opsins, b ...

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 oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrai ...

Life

Samer Hattar was born in

Amman Amman ( , ; , ) is the capital and the largest city of Jordan, and the country's economic, political, and cultural center. With a population of four million as of 2021, Amman is Jordan's primate city and is the largest city in the Levant ...

Jordan Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...

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

Christian A Christian () is a person who follows or adheres to Christianity, a Monotheism, monotheistic Abrahamic religion based on the life and teachings of Jesus in Christianity, Jesus Christ. Christians form the largest religious community in the wo ...

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 deity, deities. They also have the authority or power to administer religious rites; in parti ...

. 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 (), 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, it has been at the forefront of Jordanian and Middle E ...

Irbid Irbid (), known in ancient times as Arabella or Arbela (Άρβηλα in Ancient Greek language, Ancient Greek), is the capital and largest city of Irbid Governorate. It has the second-largest metropolitan population in Jordan after Amman, with a ...

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; ) is a private, non-sectarian, and independent university chartered in New York with its main campus in Beirut, Lebanon. AUB is governed by a private, autonomous board of trustees and offers programs le ...

Beirut Beirut ( ; ) is the Capital city, capital and largest city of Lebanon. , Greater Beirut has a population of 2.5 million, just under half of Lebanon's population, which makes it the List of largest cities in the Levant region by populatio ...

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

University of Houston The University of Houston (; ) is a Public university, public research university in Houston, Texas, United States. It was established in 1927 as Houston Junior College, a coeducational institution and one of multiple junior colleges formed in ...

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 (genetics), transcription of genetics, genetic information from DNA to messenger RNA, by binding t ...

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

. 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 university, private research university in Baltimore, Maryland. Established in 1893 following the construction of the Johns Ho ...

, 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 (chemistry), moiety of photosensitive chromoproteins, such as the pigments involved in ph ...

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, 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