Improving the understanding of cytoneme-mediated morphogen gradients by in silico modeling

Morphogen gradients are crucial for the development of organisms. The biochemical properties of many morphogens prevent their extracellular free diffusion, indicating the need of an active mechanism for transport. The involvement of filopodial structures (cytonemes) has been proposed for morphogen signaling. Here, we describe an in silico model based on the main general features of cytoneme-meditated gradient formation and its implementation into Cytomorph, an open software tool. We have tested the spatial and temporal adaptability of our model quantifying Hedgehog (Hh) gradient formation in two Drosophila tissues. Cytomorph is able to reproduce the gradient and explain the different scaling between the two epithelia. After experimental validation, we studied the predicted impact of a range of features such as length, size, density, dynamics and contact behavior of cytonemes on Hh morphogen distribution. Our results illustrate Cytomorph as an adaptive tool to test different morphogens gradients and to generate hypotheses that are difficult to study experimentally.

Improving the understanding of cytoneme-mediated morphogen gradients by in silico modeling

Morphogen gradients are crucial for the development of organisms, but there is still no agreement on the mechanisms involved in their establishment. The biochemical properties of many morphogens prevent their extracellular free diffusion, indicating the need for an active mechanism for transport. The involvement of filopodial structures (cytonemes) has been proposed for morphogen signaling, although a detailed description of the mechanism is pending. Here, we describe the development of an in silico model based on the main general features of cytoneme-meditated gradient formation and its implementation into an open software tool we named Cytomorph. We have tested the spatial and temporal adaptability of our model experimentally quantifying Hedgehog (Hh) gradient formation in Drosophila and found that Cytomorph is able to reproduce the gradient and explain its scaling between different epithelia. After experimental validation, we studied the predicted impact of a range of features such as length, size, density, dynamics and contact behavior of cytonemes on morphogen distribution. Our results illustrate Cytomorph as an adaptive tool to test and generate hypotheses that are difficult to study experimentally.

Cultural Evolution and Cultural Ecology

Chapter 3 explores cultural evolution, cultural ecology, and the ways environments shape the cultures that exist within them. It discusses whether only humans have culture, Darwin and natural selection, and biological and cultural evolution, and provides examples of biological evolution. It also addresses cultural evolution, a comparison of biological and cultural evolution, how communities change, creative cultural inventions, globalization and diffusion, revolution, and intergroup contact. It explores cultural ecology, a case study in cultural ecology, how culture and environment interconnect, sickle cell anemia, diet, lactose intolerance, culture as an adaptive tool, and cultural variability. This chapter includes a case study, Culture Across Disciplines box, chapter summary, key terms, a What Do Other Disciplines Do? section, thought-provoking questions, and class and experiential activities.