EMBARGOED
UNTIL 12:01 AM EST
Thursday,
September 25, 2008
Contact: Donna Krupa
Office: (301) 634-7209
Newsroom Phone: 843-681-0794 or 95
Cell: 703-967-2751
dkrupa@the-aps.org
Researchers Discover That
Growing Up Too Fast May Mean Dying Young In Honey Bees
New study finds that energy-expensive
behaviors in honey bees tax antioxidant capacity and elevate oxidative
damage to muscle cells, particularly in older individuals; First
experimental test of the oxidative stress model of aging in a free-living
animal
 Hilton
Head, SC–Reactive oxygen species (ROS)
occur as a by-product of aerobic metabolism and impair cellular function by
damaging proteins, nucleotides and lipids. Organisms possess a variety of
anti-oxidant mechanisms to mitigate the effects of ROS, and the oxidative
stress model of aging and senescence suggests that physiological performance
declines with age due to lifetime accrual of ROS-induced damage and
progressively limited anti-oxidant capacity. Hence, the onset, pace and
duration of energetically-intense behaviors should affect lifetime kinetics
of ROS-induced damage, anti-oxidant responses, physiological capacity and
longevity. A new study examines how these traits in honey bees are affected
by age and behavioral intensity (factors which can be experimentally
decoupled via manipulation of colony demographics), and is the first to use
such an approach to test the oxidative stress model of aging in a
free-living organism.
Background
Behavioral development in adult honeybees
involves a stereotypical transition from energetically-inexpensive hive work
to energetically-expensive foraging behavior at approximately 3 weeks of
age. Each day after this transition, a foraging bee (which weighs only 80
mg, or roughly equivalent to a breath mint) will on average fly 8 km (5
miles), contract their wing muscles approximately 4,000,000 times, and
reduce approximately 60 ml of pure oxygen in its thorax (the body segment
housing the flight muscles). Age and foraging behavior should have strong
affects on cellular oxidative stress and antioxidant mechanisms, especially
in flight muscle, as well as functional senescence. In this study the
researchers used single-cohort colonies to experimentally manipulate the
onset of foraging and compare markers of oxidative damage and antioxidant
mechanisms among different tissues (head vs. thorax), age-matched
behavioral groups (hive bees vs. foragers) and periods of the day
(morning vs. afternoon), with the prediction that such markers are
prevalent in high-intensity tissues, behaviors and day-time periods.
The study was conducted by Stephen P. Roberts,
Michelle M. Elekonich and Jason B. Williams, all of the School of Life
Sciences, University of Nevada Las Vegas. Their study was funded in part by
the National Science Foundation (NSF) and the National Institutes of Health
(NIH) and is entitled Oxidative stress and antioxidant mechanisms at the
transition to an aerobically intensive lifestyle in honey bees. Dr.
Roberts is presenting the team’s preliminary findings at the 2008 American
Physiological Society Intersociety Meeting The Integrative Biology of
Exercise V (APS;
www.the-APS.org/press).
Study Summary
Honey bees were reared in single-cohort colonies
to enable sampling and comparisons of (a) same-aged bees performing
different behaviors and (b) different-aged bees performing the same
behaviors. Comparison groups were 8-10 day-old (precocious) foragers, 8-10
day-old (typical) hive bees, 30-32 day-old (typical) foragers and 30-32
day-old (over-aged) hive bees. Antioxidant proteins Hsp70 and catalase were
measured in head and thorax tissues using western blot. Total antioxidant
capacity of the tissues was measured as the ability of homogenate to inhibit
the oxidation of ABTS®
(2,20-azino-di-[3-ethylbenzthiazolinesulphonate]) to ABTS+®
relative to trolox standards. Protein carbonylation, aconitase Vmax
inhibition and mitochondrial H2O2 production were
measured as markers of oxidative damage.
The Preliminary Study Results
The research team found that:
Foragers upregulate Hsp70, catalase
and total antioxidant capacity in their flight muscles over the course of a
day. However, these changes did not occur or were muted in forager head
tissues and hive bee flight muscles and head tissues.
The diurnal upregulation of
antioxidants and antioxidation capacity in flight muscle disappeared with
age, which may explain the impairment of flight muscle mitochondrial
function (elevated H2O2 production and reduced
aconitase Vmax) and flight capacity observed in foragers.
Conclusions
According to Dr. Roberts, the study’s first
author, “These data show that transitions to aerobically-expensive behaviors
in organisms living free in nature can have important consequences affecting
the pace of aging and senescence. The results support a
live-fast-and-die-young view of aging, but so many questions remain about
how this aging model works in natural populations, especially for species
like honey bees whose social complexity rivals our own.”
******
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS;
www.The-APS.org/press) has been an integral
part of this discovery process since it was established in 1887.
# # #
NOTE TO EDITORS: The APS Conference, The
Integrative Biology of Exercise V, is being held September 24-27, 2008
in Hilton Head, SC. Members of the media are invited to attend. To register,
or to schedule an interview with Dr. Roberts, please contact Donna
Krupa at 301.634.7209 (office), 703.967.2751 (cell) or
DKrupa@the-APS.org. There will be an APS newsroom onsite.
|
