According to the study this showing the role of environmental factors; and internal regulation in determining the growth of an organism. As the body size of a living creature has a direct impact on its fitness from the simplest animal and plant organisms right up to human beings. The individual size or height is therefore an important criterion for the ability of an organism to succeed in the competition for resources or reproduction.
But precisely which parameters regulate growth at the molecular level has hardly been investigated to date. The study demonstrating that the ambient temperature activates specific molecular signaling pathways of the growth process; and is thus involved in determining size. In addition, they showed that genetic factors also utilize identical signal pathways, likewise contributing to size regulation in the cnidarians.
Growth of an organism
From a cellular biological perspective, the size of a fully-grown organism is the result of three variables: the duration of its growth, the absolute number of the resulting cells and the individual size of all these cells, which together make up the mature organism. In the course of this characteristic growth process, the organism must be able to measure its current size, and the attainment of its maximum size.
In their study, the CAU researchers initially focused on the regulation of the number of cells of the cnidarian Hydra. But managing to identify the specific molecular signaling pathways which implement the influence of the temperature on the number of cells, and thus produce larger animals at cooler temperatures. These so-called Wnt and TGF-beta signals are involving, for example, in embryonic development and cell differentiation.
Determine the transition
The Wnt signals also determine the transition from growth to a stationary phase in Hydra. Therefore, we suspect that they serve the organism as a measuring instrument to determine its own size, before it stops growing. In addition to the ambient temperature, certain genetic information also contribute to size regulation in cnidarians. Genes that are responsible for the so calling insulin signaling pathway jointly determine the growth; among other things by controlling the number of cells during the growth phase.
In a functional gene analysis, the Kiel research team was also able to show; that switching off the genes responsible for this signaling pathway; led to body sizes up to 41% smaller in the polyps. Thus, an important role in the cellular regulation processes of growth is also playing by the genetic information. Environmental factors and genetic factors take effect one after another in a multi-step process; in a fixed hierarchical sequence, and rely on the same cellular regulatory mechanisms.