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Johannes Jaeger

EMBL/CRG Research Unit in Systems Biology, CRG - Centre de Regulacio Genomica
Dr. Aiguader 88
Barcelona, Barcelona 8003

+34 93 316 02 85

Taxa Studied: Invertebrate Animals
Techniques Employed: Degenerate PCR, 454 Pyrosequencing, Solexa (Illumina) Sequencing, Bioinformatics/Sequence Analysis, In Situ Hybridization, Antibody Staining, Epifluoresence Microscopy, Confocal Microscopy, Time-Lapse Microscopy, Transgenesis, Other, RNA interference(RNAi), Image Data Quantification, Non-Linear Optimization, Gene Network Modeling
Research Description: Our group is interested in understanding the interplay between evolution and development. Developmental processes produce the phenotypic variation available for natural selection. We have a very good understanding of how natural selection leads to adaptive change. However, very little is known about what exactly is being selected. In other words, we do not understand how developmental processes influence which kinds of adaptive changes are likely to occur and which ones are not. Our specific focus is on how changes in the structure of gene regulatory networks affect phenotypic variation. We address this question by studying the evolution of the segmentation gene network in insects, especially dipterans (flies, midges and mosquitoes). This system is comparatively well described in the literature and is experimentally tractable. In is of biological importance, since segmented body plans are a very successful design in evolution. Three major phyla (vertebrates, arthropods - including insects ?? and annelids) have body segments, which allow them to adopt a great variety of morphologies, since each segment can vary more or less independently of the rest of the body. The position and identity of insect segments are determined very early in development. In dipterans a complex, hierarchical network of segmentation genes transforms broad gradients of maternal morphogens into a striped pre-pattern of gene expression which determines where segments will form. We study the first step in this regulatory cascade, the gap gene network, using an an integrative approach which combines quantification of gene expression with mathematical modeling. We aim to quantify gap gene expression in different dipteran species, such as the moth midge (Clogmia albipunctata), a chironomid midge (Chironomus reparus) and the scuttle fly (Megaselia abdita) and to infer the regulatory interactions necessary to explain the observed expression patterns by fitting gene circuit models to the data. Gene circuits are computational tools to extract regulatory information from quantitative data. The models can then be compared to those already established in the fruit fly (Drosophila melanogaster) and predicted interactions can be tested by using RNA interference in various species and reporter constructs in Drosophila. This in silico reconstitution of the developmental and evolutionary dynamics of the gap gene system then allows us to understand which regulatory interactions changed during dipteran evolution and what specific effect each of those changes had. So far, such a quantitative description of the evolution of a developmental process has not been possible in any other experimental system.
Lab Web Page: http://www.crg.es/johannes_jaeger
Willing to Host Undergraduates: NO
Actively Seeking Undergraduates: NO
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