Neuroendocrine effects of the duper mutation in Syrian hamsters: a role for .

Molecular and physiological determinants of the timing of reproductive events, including the pre-ovulatory LH surge and seasonal fluctuations in fertility, are incompletely understood. We used the -deficient duper mutant to examine the role of this core circadian clock gene in Syrian hamsters. We find that the phase of the LH surge and its stability upon shifts of the light: dark cycle are altered in duper mutants.

Adult Neurogenesis Is Altered by Circadian Phase Shifts and the Duper Mutation in Female Syrian Hamsters.

Cell birth and survival in the adult hippocampus are regulated by a circadian clock. Rotating shift work and jet lag disrupt circadian rhythms and aggravate disease. Internal misalignment, a state in which abnormal phase relationships prevail between and within organs, is proposed to account for adverse effects of circadian disruption.

The duper mutation reveals previously unsuspected functions of in circadian entrainment and heart disease.

The ()-deficient duper mutant hamster has a short free-running period in constant darkness (τ) and shows large phase shifts in response to brief light pulses. We tested whether this measure of the lability of the circadian phase is a general characteristic of -null animals and whether it indicates resistance to jet lag. Upon advance of the light:dark (LD) cycle, both duper hamsters and mice re-entrained locomotor rhythms three times as fast as wild types.

Anatomical Methods to Study the Suprachiasmatic Nucleus.

The mammalian suprachiasmatic nucleus (SCN) functions as a master circadian pacemaker. In order to examine mechanisms by which it keeps time, entrains to periodic environmental signals (zeitgebers), and regulates subordinate oscillators elsewhere in the brain and in the periphery, a variety of molecular methods have been applied. Multiple label immunocytochemistry and in situ hybridization provide anatomical insights that complement physiological approaches (such as ex vivo electrophysiology and luminometry) widely used to study the SCN.

is a null mutation of Cryptochrome 1 in Syrian hamsters.

The duper mutation is a recessive mutation that shortens the period length of the circadian rhythm in Syrian hamsters. These animals show a large phase shift when responding to light pulses. Limited genetic resources for the Syrian hamster (Mesocricetus auratus) presented a major obstacle to cloning duper.