© 2018 Aaron A. King.

Wildlife population cycles

The data are from [1].

Blood sugar regulation

Oscillations of insulin and glucose observed during ingestion of 3 meals (A), during oral glucose (B), during continuous enteral nutrition (C), and during constant glucose infusion (D). These profiles are from 4 different subjects. Data from [2].

Regulation of blood sugar by insulin.

Regulation of blood sugar by insulin.

Hormone regulation

Frequently sampled (every 7 min), 24h profiles of plasma leptin, LH, and estradiol concentrations in 6 healthy women. Note the nocturnal rise in plasma leptin concentrations and change in LH pulse patterns from high frequency–low amplitude during the day to low frequency–high amplitude at night. Data from [3].

24h profiles of plasma hormone concentrations.

24h profiles of plasma hormone concentrations.

RNA expression

Oscillation of hes1 mRNA and Hes1 protein in cultured cells. (A) After serum treatment (t = 0), hes1 mRNA level was examined every 30 min. hes1 mRNA exhibits a 2-hour cycle oscillation. (B) After serum treatment, Hes1 protein level was examined at t = 45 min (0.75 hour) and every 30 min afterward. Hes1 protein also exhibits a 2-hour cycle oscillation; a nonspecific band (*) is relatively constant. (C) Comparison of the time course of hes1 mRNA (black line) and Hes1 protein oscillation (red line). Error bars indicate SE for each data point. Data from [4].

A biological clock composed expressed in fluctuating mRNA and protein levels.

A biological clock composed expressed in fluctuating mRNA and protein levels.

Epidemic cycles

References

1. Elton CS, Nicholson M (1942) The ten-year cycle in numbers of the lynx in Canada. Journal of Animal Ecology 11: 215–244. Available: http://www.jstor.org/stable/1358.

2. Sturis J, Polonsky KS, Mosekilde E, Van Cauter E (1991) Computer model for mechanisms underlying ultradian oscillations of insulin and glucose. American journal of physiology Endocrinology and metabolism 260: E801–E809. Available: http://ajpendo.physiology.org/content/260/5/E801.abstract.

3. Licinio J, Negrão AB, Mantzoros C, Kaklamani V, Wong ML, et al. (1998) Synchronicity of frequently sampled, 24-h concentrations of circulating leptin, luteinizing hormone, and estradiol in healthy women. Proceedings of the National Academy of Sciences of the USA 95: 2541–2546. Available: http://www.pnas.org/content/95/5/2541.

4. Hirata H, Yoshiura S, Ohtsuka T, Bessho Y, Harada T, et al. (2002) Oscillatory expression of the bHLH factor Hes1 regulated by a negative feedback loop. Science 298: 840–843. doi:10.1126/science.1074560.