Richards Group

Past projects

Branching in Streptomyces

Modelling of branching in the filamentous bacterium Streptomyces, where a critical role is played by the protein DivIVA. This work showed that new foci of DivIVA arise from an entirely novel mechanism, with new foci breaking off from existing tip foci.

Papers:

  • Richards DM, Hempel AM, Flärdh K, Buttner MJ, Howard M: Mechanistic basis of branch-site selection in filamentous bacteria. PLOS Comput Biol 8(3):e1002423 (PubMed)
  • Hempel AM, Cantlay S, Molle V, Wang SB, Naldrett MJ, Parker JL, Richards DM, Jung YG, Buttner MJ, Flärdh K: The Ser/Thr protein kinase AfsK regulates polar growth and hyphal branching in the filamentous bacteria Streptomyces. Proc Natl Acad Sci USA 109(35):E2371-9 (PubMed)
  • Flärdh K, Richards DM, Hempel AM, Howard M, Buttner MJ: Regulation of apical growth and hyphal branching in Streptomyces. Curr Opin Microbiol 15(6):737-43 (PubMed)

Telomere bouquet formation during meiosis

This work modelled how homologous chromosomes pair during meiosis, confirming the need for directed motion. For the first time we showed, using a combination of theoretical modelling and image analysis, that purely directed motion is sufficient to explain telomere nuclear motion.

Papers:

  • Richards DM, Greer E, Martin AC, Moore G, Shaw PJ, Howard M: Quantitative dynamics of telomere bouquet formation. PLOS Comput Biol 8(12):e1002812 (PubMed)
  • Richards DM, Berry S, Howard M: Illustrations of mathematical modelling in biology: epigenetics, meiosis, and an outlook. Cold Spring Harb Sym 77:175-81 (PubMed)

The multistage nature of phagocytic engulfment

Using a combination of mathematical modelling, computer simulations and image analysis, this work showed that engulfment during phagocytosis proceeds in two distinct stages, an initial slow stage followed by a much quicker second stage.

Papers:

  • Richards DM, Endres RG: The mechanism of phagocytosis: two stages of engulfment. Biophys J 107:1542-53 (PubMed)
  • Richards DM, Endres RG: Target shape dependence in a simple model of receptor-mediated endocytosis and phagocytosis. Proc Natl Acad Sci USA (PubMed)

Derivatives in morphogenesis

This work studied the robustness of boundary specification when readout involves morphogen concentration derivatives, rather than the concentration itself, showing that such models can still lead to precise positioning.

Papers:

  • Richards DM, Saunders TE: Spatiotemporal analysis of different mechanisms for interpreting morphogen gradients. Biophys J 108:2061-73 (PubMed)

Accuracy in chemotaxis

Many cells respond and move in chemical gradients, in a process called chemotaxis. Organisms must respond as accurately as possible to a range of chemical concentrations and spatial profiles. This work studied the theoretical limits to this accuracy.

Papers:

  • Micali G, Aquino G, Richards DM, Endres RG (2015) Accurate encoding and decoding by single cells: amplitude versus frequency modulation. PLOS Comput Biol 11(6):e1004222 (PubMed)