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Videos by Workshop 3: Robustness in Biological Systems

  • Robust completion time distributions in complex biological networks
    Ilya Nemenman
    Ilya Nemenman, Physics, Emory University

    Biochemical processes typically involve huge numbers of individual reversible steps, each with its own dynamical rate constants. For example, kinetic proofreading processes rely upon numerous sequential reactions in order to guarantee the precise construction of specific macromolecules. I will present a characterizati...
  • Sex, Robustness, and Evolvability
    Ricardo Azevedo
    Evolution is the movement of populations through a space of genotypes. This space can be modeled as an undirected network connecting genotypes that can be reached through mutation. In this view, the mutational robustness of a genotype is the proportion of its mutational neighbors that are viable. Robustness can facilitate the exploration of genotype networks, or evolvabili...
  • Robustness and Intragenomic Conflict
    Jon Wilkins
    When natural selection is acting at the level of the the individual phenotype, we expect selection to favor more robust phenotypes. However, selection acting at the level of the gene can undermine adaptation of the individual organism, and lead to the fixation of suboptimal traits. Genomic imprinting, the phenomenon where the pattern of expression of an allele depends on i...
  • Systematic identification of topologically essential interactions in regulatory networks
    Maxim Artyomov
    Screens monitoring the effects of deletion, knock-down or over expression of regulatory genes on the expression of their target genes are critical for deciphering the organization of complex regulatory networks. However, since perturbation assays cannot distinguish direct from indirect effects, the derived networks are significantly more complex than the true underlying on...
  • The Control of Gene Expression Noise in Embryonic Spatial Patterning
    David Holloway
    Fruit flies are models for understanding the genetic regulation involved in specifying the complex body plans of higher animals. The head-to-tail (anterior-posterior) axis of the fly (Drosophila) is established in the first hours of development. Maternally supplied factors form concentration gradients which direct embryonic (zygotic) genes where to be activated to express ...
  • The robustness continuum: yeast cells hedge their bets against unpredictable environmental change
    Mark Siegal
    Genetically identical cells grown in the same culture display striking cell-to-cell heterogeneity in gene expression and other traits. A crucial challenge is to understand how much of this heterogeneity reflects the noise tolerance of a robust system and how much serves a biological function. In some circumstances, heterogeneous traits might be favored over robust ones. Fo...
  • Robustness to gene expression errors, and the consequences for evolvability
    Joanna Masel
    Making genes into gene products is subject to predictable errors, each with a phenotypic effect that depends on a normally cryptic sequence. The distribution of fitness effects of these cryptic sequences, like that of new mutations, is bimodal. For example, a cryptic sequence might be strongly deleterious if it causes protein misfolding, or it might have only a minor effec...

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