title: Litter size manipulation in laboratory mice: an example of how proteomic analysis can uncover new mechanisms underlying the cost of reproduction.
abstract: 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.
authors.affiliation: Département Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: Marine I
authors.initials: MI
authors.lastname: Plumel
authors.affiliation: Département d'Ecologie, Physiologie et Ethologie, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 23 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Stier
authors.affiliation: Département Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: Danièle
authors.initials: D
authors.lastname: Thiersé
authors.affiliation: Département Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: Alain
authors.initials: A
authors.lastname: van Dorsselaer
authors.affiliation: Département d'Ecologie, Physiologie et Ethologie, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 23 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Criscuolo
authors.affiliation: Département Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien, CNRS UMR7178, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.|University of Strasbourg, 4 rue Blaise Pascal, F-67081 Strasbourg, Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bertile
keywords: Ageing; Mice; Oxidative stress; Proteomics; Reproduction cost; Trade-off