Who says you can't have it all?

[Guest guest]

Having it all: historical energy intakes do not generate the

anticipated trade-offs in fecundity.

* ston SL,

* Grune T,

* Bell LM,

* Murray SJ,

* Souter DM,

* Erwin SS,

* Yearsley JM,

* Gordon IJ,

* Illius AW,

* Kyriazakis I,

* Speakman JR.

Division of Energy Balance and Obesity, Rowett Research Institute,

Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK.

An axiom of life-history theory, and fundamental to our

understanding of ageing, is that animals must trade-off their

allocation of resources since energy and nutrients are limited.

Therefore, animals cannot " have it all " --combine high rates of

fecundity with extended lifespans. The idea of life-history trade-offs

was recently challenged by the discovery that ageing may be governed

by a small subset of molecular processes independent of fitness. We

tested the " trade-off " and " having it all " theories by examining the

fecundities of C57BL/6J mice placed onto four different dietary

treatments that generated caloric intakes from -21 to +8.6% of

controls. We predicted body fat would be deposited in relation to

caloric intake. Excessive body fat is known to cause co-morbidities

that shorten lifespan, while caloric restriction enhances somatic

protection and increases longevity. The trade-off model predicts that

increased fat would be tolerated because reproductive gain offsets

shortened longevity, while animals on a restricted intake would

sacrifice reproduction for lifespan extension. The responses of body

fat to treatments followed our expectations, however, there was a

negative relationship between reproductive performance (fecundity,

litter mass) and historical intake/body fat. Our dietary restricted

animals had lower protein oxidative damage and appeared able to

combine life-history traits in a manner contrary to traditional

expectations by having increased fecundity with the potential to have

extended lifespans.

PMID: 16777725 [PubMed - indexed for MEDLINE]