Biology Reference
In-Depth Information
6. RECENT ADVANCES IN CIRCANNUAL
TIMING RESEARCH
Advances in molecular biology have allowed substantial progress in
seasonal timing research, particularly in hibernation. Use of two dimensional
gel electrophoresis and mass spectrometry has uncovered changes in the pro-
teome of hibernating thirteen-lined ground squirrels (
Epperson, Rose,
Carey, & Martin, 2010; Epperson, Rose, Russel, et al., 2010; Russeth
et al., 2006
). An
in vivo
approach employing proton magnetic resonance
spectroscopy (
1
HMRS) was used tomeasure brainmetabolites during hiber-
nation in ground squirrels (
Henry et al., 2007
). Next-generation sequencing,
including Roche 454 (
Hampton et al., 2011
) and more recently Illumina
HiSeq 2000 (
Schwartz et al., 2013
), has uncovered transcriptional changes
during hibernation in several tissues of the thirteen-lined ground squirrel.
Additionally, microarrays have been recently utilized to analyze seasonal
gene expression changes in song control regions in sparrows (
Mukai et al.,
2009; Thompson et al., 2012
).
Further advancing research in circannual timing, the Broad Institute of
MIT and Harvard
(
http://www.broad.mit.edu
)
has sequenced the genomes
of four hibernating mammals over the last decade, including
Ictidomys
(for-
merly
Spermophilus
)
tridecemlineatus
(thirteen-lined ground squirrel),
Myotis
lucifugus
(little brown bat),
Eptesicus fuscus
(big brown bat), and
Erinaceus euro-
paeus
(common hedgehog). There are few genomic resources available for
migrating bird species, although recently a genome-wide single nucleotide
polymorphism set was developed for the barnacle goose (
Branta leucopsis
)
(
Jonker et al., 2012
). The genome of the zebra finch (
Taeniopygia guttata
)
has been sequenced as well (
Warren et al., 2010
), and while this is not a sea-
sonal breeding/singing species, it does exhibit plasticity associated with song
learning in the brain during juvenile development (
Brenowitz & Beecher,
2005
), which could provide clues about the pathways underlying seasonal
plasticity in songbird brains.
In addition to recent technological advancements and approaches mak-
ing it easier to examine molecular changes in nonmodel organisms, there
have also been advances in genetic manipulations of nonmodel organisms
used in seasonal studies. Recently, we published a study using adenovirus
to overexpress the metabolic hormone
FGF21
at several different points
during the year in thirteen-lined ground squirrels (
Nelson et al., 2013
). This
transgenic approach sets the stage for similar studies in nonmodel organisms
