[MARMAM] New Paper: Northern Elephant Seal Muscle Physiology

Tray Wright traywright at tamu.edu
Thu Oct 15 08:50:42 PDT 2020


Colleagues,
We are pleased to present our recent publication: "*Changes in Northern
Elephant Seal Skeletal Muscle Following Thirty Days of Fasting and Reduced
Activity*", freely available in Frontiers in Physiology:
https://doi.org/10.3389/fphys.2020.564555

*Changes in Northern Elephant Seal Skeletal Muscle Following Thirty Days of
Fasting and Reduced Activity*
Northern elephant seals (NES, Mirounga angustirostris) undergo an annual
molt during which they spend ∼40 days fasting on land with reduced activity
and lose approximately one-quarter of their body mass. Reduced activity and
muscle load in stereotypic terrestrial mammalian models results in
decreased muscle mass and capacity for force production and aerobic
metabolism. However, the majority of lost mass in fasting female NES is
from fat while muscle mass is largely preserved. Although muscle mass is
preserved, potential changes to the metabolic and contractile capacity are
unknown. To assess potential changes in NES skeletal muscle during molt, we
collected muscle biopsies from 6 adult female NES before the molt and after
∼30 days at the end of the molt. Skeletal muscle was assessed for
respiratory capacity using high resolution respirometry, and RNA was
extracted to assess changes in gene expression. Despite a month of reduced
activity, fasting, and weight loss, skeletal muscle respiratory capacity
was preserved with no change in OXPHOS respiratory capacity. Molt was
associated with 162 upregulated genes including those favoring lipid
metabolism. We identified 172 downregulated genes including those coding
for ribosomal proteins and genes associated with skeletal muscle force
transduction and glucose metabolism. Following ∼30 days of molt, NES
skeletal muscle metabolic capacity is preserved although
mechanotransduction may be compromised. In the absence of exercise
stimulus, fasting-induced shifts in muscle metabolism may stimulate
pathways associated with preserving the mass and metabolic capacity of slow
oxidative muscle.

Cheers,
Tray

Traver Wright, Ph.D.
Research Assistant Professor
Department of Health and Kinesiology
Texas A&M University
675 John Kimbrough Blvd
College Station, TX 77843-4253
(409) 692-4120
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