Developmental plasticity in craniodental structures: Assessing the response to systemic factors using rodent models

GONZALEZ P; BERNAL V.; D`ADDONA L; LOTTO F.; HALLGRIMSSON B

Congreso; 46. 83rd Annual Meeting of the American Association of Physical Anthropologists.; 2014

In the course of their development, phenotypic traits are under the influence of systemic factors with a widespread effect across several structures as well as factors with localized effects. Disentangling the contribution of specific factors to variation in size and shape of morphological traits is difficult to achieve in natural populations due to the overlap of multiple developmental processes during individual ontogeny. Thus, animal models are essential for determining how morphology is modulated by developmental processes. Here, we assess the effect of two systemic factors -nutrient intake and growth hormone level- which coordinate organismal growth by regulating the GH-IGF axis, on the development of the skull and molar teeth. The experimental modelsused were: a) mice fed on a low protein diet during pre and postnatal ontogeny and b) GH deficient mice. We obtained 3D micro CT images of the skull and digitized landmarks and semilandmarks in order to assess size and shape changes among control and treatment groups. Alteration of normal growth resulted in a significantlyrounded braincase and a shorter and wider face. Molar size was significantly reduced, and molar proportions changed according to the predictions of an inhibitory-cascade model of development. Molar shape was also altered due to the differential effect on structures with a later ontogenetic origin. Our results show that GH and environmental stimuli induced similar responses, and that the magnitude and direction of changes depended on both the timing of the perturbation and the intrinsic trajectory of development of the traits.