The XMAP215-family protein DdCP224 is required for cortical interactions of microtubules

BACKGROUND: Interactions of peripheral microtubule tips with the cell cortex are of crucial importance for nuclear migration, spindle orientation, centrosome positioning and directional cell movement. Microtubule plus end binding proteins are thought to mediate interactions of microtubule tips with cortical actin and membrane proteins in a dynein-dependent manner. XMAP215-family proteins are main regulators of microtubule plus end dynamics but so far they have not been implicated in the interactions of microtubule tips with the cell cortex. RESULTS: Here we show that overexpression of an N-terminal fragment of DdCP224, the Dictyostelium XMAP215 homologue, caused a collapse of the radial microtubule cytoskeleton, whereby microtubules lost contact with the cell cortex and were dragged behind like a comet tail of an unusually motile centrosome. This phenotype was indistinguishable from mutants overexpressing fragments of the dynein heavy chain or intermediate chain. Moreover, it was accompanied by dispersal of the Golgi apparatus and reduced cortical localization of the dynein heavy chain indicating a disrupted dynein/dynactin interaction. The interference of DdCP224 with cortical dynein function is strongly supported by the observations that DdCP224 and its N-terminal fragment colocalize with dynein and coimmunoprecipitate with dynein and dynactin. CONCLUSIONS: Our data show that XMAP215-like proteins are required for the interaction of microtubule plus ends with the cell cortex in interphase cells and strongly suggest that this function is mediated by dynein

Habitat preferences of male Corn Buntings Emberiza calandra in north-eastern Germany

Agricultural ecosystems have faced dramatic changes during past decades, resulting in a dramatic loss of farmland biodiversity. The Corn Bunting Emberiza calandra is considered a suitable indicator for the conservation value of farmland habitats, and has recently suffered strong declines throughout much of its European range. As a basis for targeted conservation measures, we investigated the habitat preferences of this species in north-eastern Germany by comparing the composition of male territories with randomly chosen control sites. A territory was defined as the area within a radius of 150 meters around the assumed centre of the territory, as the majority of nests is found within this radius. To assess food availability for nestlings, arthropod abundance within the most abundant land use types i.e. crop fields, fallows, grassland as well as within unploughed strips was investigated. In total we found 102 male Corn Bunting territories, which were mainly composed of crop fields (50%), grassland (28%), and fallows (12%). Territories compared with control sites were characterized by a lower proportion of crop fields, a higher proportion of fallows, more diverse land use types, more abundant field boundaries, unploughed strips, and tracks, and a higher availability of song posts. However, neither the number of larger (>= 1 cm), smaller ( 10%) and song posts (> 70 m 'linear song posts' or > 1 solitary post per ha) for the habitat selection of male Corn Buntings. We conclude that measures to halt population declines of Corn Buntings seem to be relatively easy to implement, provided that farmers are granted a fair compensation