Daylight study reveals how animals adapt between seasons

Date:
August 27, 2020
Source:
University of Edinburgh
Summary:
Scientists have discovered how a biological switch helps animals
make the seasonal changes crucial for survival, such as growing
a warm winter coat and adjusting body temperatures.



FULL STORY ========================================================================== Scientists have discovered how a biological switch helps animals make
the seasonal changes crucial for survival, such as growing a warm winter
coat and adjusting body temperatures.


==========================================================================
The findings reveal how the brain responds to short and long days to allow animals to adapt to changing conditions and governs vital behaviour such
as breeding cycles.

Researchers say the study in sheep could help explain the timings of
seasonal adaptations in a number of species such as birds, reptiles
and mammals.

The body's internal clock choreographs cycles in hormone levels and
affects traits such as sleep and hunger. These alter over the course of
the day - - known as circadian rhythms -- and are influenced by genetics.

Similar rhythms are also seen seasonally, but until now it was unclear
how genes play a role in the biological changes that fluctuate between
winter and summer.

Researchers led by the Universities of Edinburgh and Manchester studied
an endocrine gland attached to the brain called the pituitary gland in
sheep experiencing short or long lengths of day.



========================================================================== Brain tissue was analysed for gene activity across time, allowing
scientists to observe the biological processes that happen in response
to different day lengths.

They found that one of two possible biological mechanisms is activated
within the pituitary gland depending on whether the day is long or short.

In summer when nights are long, the brain generates hormones that cause a cascade of gene activity leading to biological characteristics associated
with summer.

When nights are short in winter, the switch is flipped -- night-time
hormones are released for longer, triggering biological processes linked
to winter.

The study found that in the sheep brain, both processes involve a
circadian gene known as BMAL2, which is found in many animals but whose
role in the seasonal clock was previously unknown.

The study, published in Nature Communications, was funded by the
Biotechnology and Biological Sciences Research Council.

The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of
the University of Edinburgh's Royal (Dick) School of Veterinary Studies.

Professor Simone Meddle, who co-led the research from the University
of Edinburgh's Roslin Institute, said: "Fluctuations in hormones and
behaviour are part of a delicate biological orchestra that is crucial
to life. Many animals depend on seasonal changes in their biology to
survive and our findings are a crucial part of the puzzle to understand
the underlying processes." Professor Andrew Loudon, who co-led the
study from the University of Manchester, said: "The genetic 'flip-flop'
timer we have identified is key to functions such as fertility as sheep transition between winter and summer. We speculate that this genetic
timer is likely to be fundamental to yearly changes in many species."

========================================================================== Story Source: Materials provided by University_of_Edinburgh. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. S. H. Wood, M. M. Hindle, Y. Mizoro, Y. Cheng, B. R. C. Saer, K.

Miedzinska, H. C. Christian, N. Begley, J. McNeilly, A. S. McNeilly,
S.

L. Meddle, D. W. Burt, A. S. I. Loudon. Circadian clock mechanism
driving mammalian photoperiodism. Nature Communications, 2020; 11
(1) DOI: 10.1038/s41467-020-18061-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200827101826.htm

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