Making the Body Plan: Precision in the Genetic Hierarchy of Drosophila Embryo Segmentation

Issue title: 3rd International Conference on Bioinformatics of Genome Regulation and Structure (BGRS 2002), June 2002, Novosibirsk, Russia

Article type: Research Article

Authors: Spirov, Alexander V.^; | Holloway, David M.

Affiliations: Department of Applied Mathematics and Statistics and The Center for Developmental Genetics, The State University of New York at Stony Brook, New York, 11794-3600, USA. Tel.: +1 631 632 8352; Fax: +1 631 632 8490; E-mail: [email protected] | The Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sci-ences, 44 Thorez Ave., St. Petersburg, 194223, Russia | Mathematics Department, British Columbia Institute of Technology, 3700 Willingdon Ave., Burnaby, B.C., Canada, V5G 3H2; and Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, B.C., Canada, V6T 1Z1. Tel.: +1 604 456 8199; Fax: +1 604 432 9173, E-mail: [email protected]

Note: [] Corresponding author

Abstract: We quantify fluctuations in protein expression for three of the segmentation genes in the fruit fly, Drosophila melanogaster. These proteins are representative members of the first three levels of a signalling hierarchy which determines the segmented body plan: maternal (Bicoid protein); gap (Hunchback protein); and pair-rule (Even-skipped protein). We quantify both inter-embryo and inter-nucleus (within a single embryo) variability in expression, especially with respect to positional specification by concentration gradient reading. Errors are quantified both early and late in cleavage cycle 14, during which the protein patterns develop, to study the dynamics of error transmission. We find that Bicoid displays very large positional errors, while expression of the downstream genes, Hunchback and Even-skipped, displays far more precise positioning. This is evidence that the pattern formation of the downstream proteins is at least partially independent of maternal signal, i.e. evidence against simple concentration gradient reading. We also find that fractional errors in concentration increase during cleavage cycle 14.

Keywords: morphogens, pattern formation, gradient reading, genetic cascades, positional information, gene networks, signalling hierarchy, concentration noise, embryo segmentation, maternal genes, gap genes, pair-rule genes, embryo-to-embryo variability, nucleus-to-nucleus variability, genetic algorithms, stochastic, error transmission, axis specification, image processing, Drosophila melanogaster

Journal: In Silico Biology, vol. 3, no. 1-2, pp. 89-100, 2003