Nutrient signaling and developmental timing of maturation

Curr Top Dev Biol. 2013;105:37-67. doi: 10.1016/B978-0-12-396968-2.00002-6.

Abstract

In animals, developmental timing of sexual maturation is tightly linked to nutrition and growth. Maturation only occurs once the juvenile has acquired sufficient nutrients and completed enough growth to produce a reproductively mature adult with a genetically predefined body size. Animals therefore adjust the duration of juvenile development to the dietary conditions. When nutrients are scarce the juvenile growth phase is extended to compensate for slow growth. Conversely, development is accelerated in nutrient rich environments where animals rapidly reach their genetic target size. To achieve such flexibility, nutrient-dependent growth regulators must feed into the endocrine system that controls the timing of maturation. Work on the fruit fly Drosophila has revealed a central role of secreted signal molecules with similarity to the conserved insulin-like growth factors (IGFs) in the decision making process. These molecules are involved in checkpoints that allow the endocrine system to decide whether to release the steroid hormone, ecdysone, that triggers maturation or extent development, depending on nutrient levels and growth status. Importantly, different dietary components influence timing of maturation in Drosophila, with proteins having the greatest impact; fat and sugar play a minor role, at least within the limits of what can be considered a balanced diet. Remarkably, excess dietary sugar concentrations that mimic physiological conditions associated with diabetes, negatively affect growth and delays maturation. Altogether, this shows that the source of energy in the diet is important for timing and may provide a paradigm for understanding the emerging links between diet, obesity and diabetes, and the onset of puberty. Here, we provide an overview of the system underlying developmental timing of maturation in Drosophila and review recent success in understanding its coupling to nutrition and growth.

Keywords: Checkpoints; Diet; Drosophila; Ecdysone; Steroids.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animal Nutritional Physiological Phenomena / drug effects
  • Animal Nutritional Physiological Phenomena / physiology*
  • Animals
  • Dietary Proteins / pharmacology*
  • Dietary Sucrose / pharmacology*
  • Energy Metabolism / physiology*
  • Growth and Development / drug effects
  • Growth and Development / physiology*
  • Insulin / metabolism
  • Models, Biological
  • Sexual Maturation / drug effects
  • Sexual Maturation / physiology*
  • Signal Transduction / physiology*
  • Species Specificity
  • TOR Serine-Threonine Kinases / metabolism
  • Time Factors

Substances

  • Dietary Proteins
  • Dietary Sucrose
  • Insulin
  • TOR Serine-Threonine Kinases