Litter size manipulation in laboratory mice: an example of how proteomic analysis can uncover new mechanisms underlying the cost of reproduction
Résumé
Background: Life history theories predict that investment in current reproduction comes at a cost for future
reproduction and survival. Oxidative stress is one of the best documented mechanisms underlying costs of
reproduction to date. However, other, yet to be described molecular mechanisms that play a short term role during
reproduction may explain the negative relationships underlying the cost of reproduction. To identify such new
mechanisms, we used a global proteomic determination of liver protein profiles in laboratory adult female mice
whose litter size had been either reduced or enlarged after birth. This litter size manipulation was expected to
affect females by either raising or decreasing their current reproductive effort. At the same time, global parameters
and levels of oxidative stress were also measured in all females.
Results: Based on plasma analyses, females with enlarged litters exhibited increased levels of oxidative stress at the
date of weaning compared to females with reduced litters, while no significant difference was found between both
the latter groups and control females. None of the liver proteins related to oxidative balance were significantly
affected by the experimental treatment. In contrast, the liver protein profiles of females with enlarged and reduced
litters suggested that calcium metabolism and cell growth regulation were negatively affected by changes in the
number of pup reared.
Conclusions: Plasma oxidative stress levels in reproductive mice revealed that the degree of investment in
reproduction can actually incur a cost in terms of plasmatic oxidative stress, their initial investment in reproduction
being close to maximum and remaining at a same level when the energy demand of lactation is reduced. Liver
proteomic profiles in reproductive females show that hepatic oxidative stress is unlikely to be involved in the cost
of reproduction. Reproductive females rather exhibited liver protein profiles similar to those previously described in
laboratory ageing mice, thus suggesting that hepatic cell pro-ageing processes may be involved in the cost of
reproduction. Overall, our data illustrate how a proteomic approach can unravel new mechanisms sustaining
life-history trade-offs, and reproduction costs in particular.
Domaines
Sciences de l'environnement
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