Metabolism of tryptophan and serotonin by the chick pineal gland in organ culture

1990

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Young chicks were raised under a standard cycle of illumination and their pineal glands were cultured in organ culture. We have already reported a rhythmic daily cycle in the cumulative incorporation of thymidine into DNA when the glands were incubated under the cycle of illumination to which they were entrained in vivo. Incorporation ceased shortly after the end of the photoperiod and resumed again at, or shortly after, start of the following photoperiod. We have now shown that this cycle was entrained to other lighting schedules and largely unaffected by the time of explanting into culture. The rhythm also persisted in glands cultured in constant darkness. However, when the cycle was maintained by daily renewal of the culture medium it was markedly affected by changes in the time of day at which medium was renewed. Results for glands cultured under constant illumination were inconsistent.

Section: Methodsmentioning

confidence: 98%

Entrainment of the Rhythm in Thymidine Incorporation by Cultured Chick Pineal Glands

1990

Self Cite

“…Our experimental procedures have been reported in detail in previous studies [Wainwright, 1977;Wainwright and Wainwright, 1978;Wainwright et al, 19891. They have also been recently summarized [Wainwright and Wainwright, 19911. All experiments used pineal glands from White Leghorn chicks aged 7-9 days posthatch, kept under a cycle of illumination with a photoperiod of 14 hr.…”

Section: Materials Gnd Methodsmentioning

confidence: 99%

“…We have recently demonstrated a circadian rhythm in rate of thymidine incorporation by cultured intact chick pineal glands that appears to be controlled by mechanisms distinct from those regulating the normal cell cycle [Wainwright andWainwright, 1989, 1990a,b, 19911. This rhythm is "complementary" to that in level of NAT activity in at least two major respects.…”

Section: Introductionmentioning

confidence: 99%

“…First, incorporation is largely confined to cells of the stroma [Wainwright et al, 19891. Second, increase in the rate of incorporation begins at (or very shortly after) start of the new photoperiod [Wainwright andWainwright, 1989a, 1990al and becomes maximal late in the photoperiod. In contrast, NAT activity begins to rise shortly before the end of the photoperiod and is maximal late in the dark period [e.g., Wainwright and Wainwright, 19791.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Purinergic receptors have no major role in control of the circadian rhythm in rate of thymidine incorporation by cultured chick pineal glands

1991

We have examined the effects of some analogues of adenosine upon the circadian rhythm in rate of thymidine incorporation by cultured chick pineal glands. Incorporation in the early period of the photoperiod on day 2 of culture was slightly inhibited by the adenosine analogue N-ethylcarboxamido-adenosine, but this effect was not countered by the antagonist 8-phenyl-theophylline. Thymidine incorporation was inhibited when glands were continuously exposed to the adenosine transport inhibitor nitrobenzyl-thioinosine, but ongoing incorporation was not inhibited by addition of this agent. Removal of adenosine and deoxyadenosine supplements from the medium, with or without further addition of adenosine deaminase, had no appreciable effects upon thymidine incorporation. We conclude that adenosine and analogues probably play no role in regulation of the rhythm in rate of thymidine incorporation.

“…Most of our experimental procedures have been reported in detail in previous studies [Wainwright, 1977[Wainwright, , 1980Wainwright and Wainwright, 19781, and these are therefore only summarized here.…”

Section: Methodsmentioning

confidence: 99%

On Thymidine Incorporation by the Cultured Chick Pineal Gland

Lucarotti

1989

Explanted chick pineal glands exhibited a cycle in thymidine incorporation when cultured either under a cycle of illumination or in constant darkness. This cycle appeared to be entrained to the light cycle under which the birds were maintained. The incorporation reflected gene replication in a small fraction of the cell population that was largely, but not entirely, located in the stroma of the gland. Glands cultured with colchicine for 28 h contained a very small number of cells showing metaphase chromosomes.