A new strategy, enhancer trapping, provide a novel way to detect in situ a gene activity involved in the neurogenesis of Drosophila. E. coli lacZ gene fused with a weak promotor of Drosophila are randomly integrated into the genome. lacZ is expressed in a spatio-temporal-specific mammer under the control of the enhancer located nearby an inserted sequence. The applications of this new methd to study the postembryonic development in Drosophila are discussed.
Replicated daughter chromosomes in Escherichia coli move nonprogressively and abruptly from midcell toward the quarter positions at the early D (division) period. The chromosome positioning is controlled by the mukA and mukB gene products. The mukA (tolC) gene encodes an outer membrane protein. Sequencing results of the mukB gene suggest that the MukB protein (177kDa) has 5 distinct secondary structural domains, and two MukB protein molecules from ca homodimer in coiled-coil regions, like myosin and kinesin of eukaryotic cells. MukB may provide the force required for the chromosome positioning and the amino terminal globular domain cntaining an ATP binding sequence may act as a "motor" domain.
Glycoproteins and proteoglycans in extracellular matrices and at cell surfaces are known to be involved in a variety of recognition and adhesion processes of cells. The carbohydrate structures of these glycoconjugates are induced to change by development, differentiation and malignant transformation of cells. Such intrinsic structures of the sugar chains are turned out to be important for the functions of these molecules and in some cases are directly involved in dynamic biological phenomena. This review will pick up the current knowledge of the sugar chains of glycoproteins and proteoglycans in extracellular matrices and at cell surfaces.