Seeing the light: Model system probes photoperiod gene response

Research Areas:

Photoperiodism, Melatonin, Thyroid stimulating hormone, Bioluminescence, Luciferase

Imaging Needs:

Excellent low-light performance

Imaging System:
  • Olympus MVX10 macrozoom microscope
  • Tokai Hit heated culture chamber at 37 °C
  • Olympus 1.6x Plan Apochromat objective with 6.3x zoom
  • Hamamatsu ImagEM C9100 EM-CCD camera cooled to -80 °C
  • snapshots: 29-minute image exposure time; time-lapse: 14-minute exposure time
  • Molecular Devices MetaMorph software
  • Hamamatsu LM-2400 bioluminescence detection system for photon counts
Seeing the brain in action

New imaging techniques are promising to reveal more about neural connections in the brain than ever before. See how Misha Ahrens, Philipp Keller, and colleagues use lightsheet microscopy to visualize the intact, living brain in real time. Read now.

THE QUESTION

How do mammals adjust their physiology to suit the seasons?

As winter gives way to spring and summer, most living things respond to the longer daylight periods with physiological adjustments. In mammals, long days induce expression of the thyroid-stimulating hormone beta subunit (TSHβ) in the pituitary gland. The pituitary in turn mediates other adaptations to the longer photoperiod and changing seasons.

THE BARRIERS

How does a change in light exposure upregulate TSHβ? The pituitary gland is rich in receptors for the hormone melatonin, which is thought to communicate nighttime darkness to the brain. What molecular mediators signal daytime in the pituitary? The search for candidates requires a ready means to measure TSHβ response in living tissue.

THE SOLUTION

Establishment of TSHβ real-time monitoring system in mammalian photoperiodism
Kaori Tsujino, Ryohei Narumi, Koh-hei Masumoto, Etsuo A. Susaki, Yuta Shinohara, Takaya Abe, Masayuki Iigo, Atsushi Wada, Mamoru Nagano, Yasufumi Shigeyoshi and Hiroki R. Ueda
Genes Cells. 2013 Jul 18(7): 575–588. PMCID: PMC3738941.

Tsujino et al,1 screened candidate molecules for mediators of the TSHβ response by measuring bioluminescence in cultured murine pituitary tissue slices expressing TSHβ tagged with luciferase. Using a Hamamatsu ImagEM C9100 EM-CCD camera for images and a Hamamatsu LM-2400 detection system for photon counts, the researchers showed an increase in TSHβ production following exposure to melatonin.

The results were consistent with those of in vivo experiments, confirming the usefulness of the tissue-slice bioluminescence experimental setup for studying TSHβ expression and photoperiod response.

THE POSSIBILITIES

Tsujino et al. used the Hamamatsu ImagEM C9100 EM-CCD camera’s outstanding low-light performance to capture changes in bioluminescence-labeled gene expression in living tissues in vitro. A new lightsheet microscopy method is helping researchers to locate functional indicators at the cellular level in vivo. Read about this new approach, developed by Misha Ahrens, Philipp Keller, and colleagues using Hamamatsu’s ORCA-Flash4.0 camera, in Seeing the Living Brain.

References

  1. Tsujino, et al. Establishment of TSHβ real-time monitoring system in mammalian photoperiodism. Genes Cells. 2013 Jul 18(7): 575–588. PMCID: PMC3738941.
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