Egg size-dependent expression of growth hormone receptor accompanies compensatory growth in fish

Segers, F.H.I.D., Berishvili, G., & Taborsky, B. (2012). Egg size-dependent expression of growth hormone receptor accompanies compensatory growth in fish. Proceedings of the Royal Society B: Biological Sciences 279 (1728) 592-600. 10.1098/rspb.2011.1104.

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Large egg size usually boosts offspring survival, but mothers have to trade off egg size against egg number. Therefore, females often produce smaller eggs when environmental conditions for offspring are favourable, which is subsequently compensated for by accelerated juvenile growth. How this rapid growth is modulated on a molecular level is still unclear. As the somatotropic axis is a key regulator of early growth in vertebrates, we investigated the effect of egg size on three key genes belonging to this axis, at different ontogenetic stages in a mouthbrooding cichlid (Simochromis pleurospilus). The expression levels of one of them, the growth hormone receptor (GHR), were significantly higher in large than in small eggs, but remarkably, this pattern was reversed after hatching: young originating from small eggs had significantly higher GHR expression levels as yolk sac larvae and as juveniles. GHR expression in yolk sac larvae was positively correlated with juvenile growth rate and correspondingly fish originating from small eggs grew faster. This enabled them to catch up fully in size within eight weeks with conspecifics from larger eggs. This is the first evidence for a potential link between egg size, an important maternal effect, and offspring gene expression, which mediates an adaptive adjustment in a relevant hormonal axis.

Item Type: Article
Uncontrolled Keywords: Maternal effects; Egg size; Gene expression; Compensatory growth
Research Programs: Evolution and Ecology (EEP)
Bibliographic Reference: Proceedings of the Royal Society B: Biological Sciences; 279(1728):592-600 (7 February 2012) (Published online 13 July 2011)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 08:46
Last Modified: 23 Aug 2016 09:37

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