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Rae Silver, Ph.D.

Kaplan Professor

E-mail: qr@columbia.edu

Identification and functional analysis of the mammalian "biological clock"

picture All organisms have internal biological clocks that serve to recognize local time of day and to temporally organize behavioral and physiological functions. Circadian rhythms continue to oscillate within an approximate 24-hour period in the absence of external cues, although ordinarily these rhythms are synchronized to the day-night cycle. The functional components of the "biological clock" include an input pathway that synchronizes to the environment, a pacemaker that generates the oscillation, and output pathways that control overt rhythms. The circadian system has marked implications for shift work and jet lag. Research in the lab uses a variety of neuroanatomical and molecular techniques to study this system, including neural tissue transplants, immunohistochemistry, in situ hybridization, PCR, cell and tissue culture, and reporter gene technology

Behaviorally triggered appearance of mast cells in the brain

We have discovered that sexual behavior triggers the appearance of mast cells in the brain of doves, and that sex steroids activate brain mast cells, causing them to release their contents. This is a new mode of communication between the immune, neural and endocrine systems. These immunocytes, serving as mobile single cell glands, are likely to be a phylogenetically ancient system that rapidly delivers otherwise unavailable biologically active materials to specific brain regions upon demand. Currently, we are working on understanding the function of brain mast cells in avian and mammalian species.

Selected publications

Saldanha CJ, Silverman AJ, Silver R. 2001. Direct innervation of GnRH neurons by encephalic photoreceptors in birds. J Biol Rhythms. 1:39-49.

Bryant DN, LeSauter J, Silver R, Romero MT. 2000. Retinal innervation of calbindin-D28K cells in the hamster suprachiasmatic nucleus: ultrastructural characterization. J Biol Rhythms. 2:103-11.

Wilhelm M, King B, Silverman AJ, Silver R. 2000. Gonadal steroids regulate the number and activational state of mast cells in the medial habenula. Endocrinology. 3:1178-86.

Deviche P, Saldanha CJ, Silver R. 2000. Changes in brain gonadotropin-releasing hormone- and vasoactive intestinal polypeptide-like immunoreactivity accompanying reestablishment of photosensitivity in male dark-eyed juncos (Junco hyemalis). Gen Comp Endocrinol. 117(1):8-19.

Silver R, LeSauter J, Tresco P, Lehman MN. 1996. A diffusible coupling signal form the transplanted suprachiasmatic nucleus controlling circadian locomotor rhythms. Nature. 382: 810-813.

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Last modified on August 7, 2001