title: Stochastic model for gene transcription on Drosophila melanogaster embryos.
abstract: We examine immunostaining experimental data for the formation of stripe 2 of even-skipped (eve) transcripts on D. melanogaster embryos. An estimate of the factor converting immunofluorescence intensity units into molecular numbers is given. The analysis of the eve dynamics at the region of stripe 2 suggests that the promoter site of the gene has two distinct regimes: an earlier phase when it is predominantly activated until a critical time when it becomes mainly repressed. That suggests proposing a stochastic binary model for gene transcription on D. melanogaster embryos. Our model has two random variables: the transcripts number and the state of the source of mRNAs given as active or repressed. We are able to reproduce available experimental data for the average number of transcripts. An analysis of the random fluctuations on the number of eves and their consequences on the spatial precision of stripe 2 is presented. We show that the position of the anterior or posterior borders fluctuate around their average position by ∼1% of the embryo length, which is similar to what is found experimentally. The fitting of data by such a simple model suggests that it can be useful to understand the functions of randomness during developmental processes.
authors.affiliation: Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Avenida Arlindo Béttio, 1000, Ermelino Matarazzo, São Paulo, SP CEP 03828-000, Brazil.
authors.forename: Guilherme N
authors.initials: GN
authors.lastname: Prata
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-Carlense, 400, São Carlos, SP CEP 13566-590, Brazil.
authors.forename: José Eduardo M
authors.initials: JE
authors.lastname: Hornos
authors.affiliation: Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Avenida Arlindo Béttio, 1000, Ermelino Matarazzo, São Paulo, SP CEP 03828-000, Brazil.|Departamento de Radiologia - Faculdade de Medicina, Universidade de São Paulo, São Carlos, SP CEP 13566-590, Brazil.|Núcleo de Estudos Interdisciplinares em Sistemas Complexos, Universidade de São Paulo, São Carlos, SP CEP 13566-590, Brazil.
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Ramos
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D008957:Models, Genetic; D013269:Stochastic Processes; D014158:Transcription, Genetic