Steffen Lemke

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To identify unknown proteins from plant peroxisomes, the Arabidopsis genome was screened for proteins with putative major or minor peroxisome targeting signals type 1 or 2 (PTS1 or PTS2), as defined previously (Reumann S [2004] Plant Physiol 135: 783-800). About 220 and 60 proteins were identified that carry a putative PTS1 or PTS2, respectively. To further(More)
Higher cyclorrhaphan flies including Drosophila develop a single extraembryonic epithelium (amnioserosa), which closes the germband dorsally. In most other insects two extraembryonic epithelia, serosa and amnion, line the inner eggshell and the ventral germband, respectively. How the two extraembryonic epithelia evolved into one is unclear. Recent studies(More)
The homeobox gene bicoid functions as an anterior pattern organizer of the Drosophila embryo, but other than in higher flies (Cyclorrhapha), bicoid orthologues appear to be absent from insect genomes. In Drosophila, bicoid is expressed in an anterior-to-posterior protein gradient and regulates spatially restricted expression domains of segmentation genes in(More)
Bone morphogenetic protein (BMP) signaling is an essential factor in dorsoventral patterning of animal embryos but how BMP signaling evolved with fundamental changes in dorsoventral tissue differentiation is unclear. Flies experienced an evolutionary reduction of extra-embryonic tissue types from two (amniotic and serosal tissue) to one (amnionserosal(More)
Most insect embryos develop from a monolayer of cells around the yolk, but only part of this blastoderm forms the embryonic rudiment. Another part forms extra-embryonic serosa. Size and position of the serosa anlage vary between species, and previous work raises the issue of whether such differences co-evolve with the mechanisms that establish(More)
The hemispheric, bi-layered optic cup forms from an oval optic vesicle during early vertebrate eye development through major morphological transformations. The overall basal surface, facing the developing lens, is increasing, while, at the same time, the space basally occupied by individual cells is decreasing. This cannot be explained by the classical view(More)
The metameric organization of the insect body plan is initiated with the activation of gap genes, a set of transcription-factor-encoding genes that are zygotically expressed in broad and partially overlapping domains along the anteroposterior (AP) axis of the early embryo. The spatial pattern of gap gene expression domains along the AP axis is generally(More)
The homeobox gene caudal (cad) regulates posterior development in Drosophila. In early embryos, the cad protein (CAD) is expressed in a posterior-to-anterior concentration gradient, which contributes polarity to the developing embryo. The CAD gradient is complementary to and dependent on the anterior pattern organizer Bicoid (BCD), which represses the(More)
The amnioserosa is an extraembryonic epithelium that evolved in higher cyclorrhaphan flies from distinct serosal and amniotic epithelia. The underlying genetic mechanism of this evolutionary transition is unknown. Amnioserosa development of Drosophila correlates with novel expression characteristics of the homeobox gene zerknüllt (zen), including a broad(More)