Plant cells are caged within a distended polymeric network (the cell wall), which enlarges by a process of stress relaxation and slippage (creep) of the polysaccharides that make up the load‐bearing network of the wall. Protein mediators of wall creep have recently been isolated and characterized. These proteins, called expansins, appear to disrupt the noncovalent adhesion of matrix polysaccharides to cellulose microfibrils, thereby permitting turgor‐driven wall enlargement. Expansin activity is specifically expressed in the growing tissues of dicotyledons and monocotyledons. Sequence (...) analysis of cDNAs indicates that expansins are novel proteins, without previously known functional motifs. Comparison of expansin cDNAs from cucumber, pea, Arabidopsis and rice shows that the proteins are highly conserved in size and amino acid sequence. Phylogenetic analysis of expansin sequences suggests that this multigene family diverged before the evolution of angiosperms. Speculation is presented about the role of this gene family in plant development and evolution. (shrink)

Used for everything from geographic evaluation to secret spy missions, aerial photography has a rich and storied history, ably recounted here in Photography and Flight. Aerial photography is marked by its dependency on technological developments in both photography and aerospace, and the authors chart the history of this photography as it tracked the evolution of these technologies. Beginning with early images taken from hot-air balloons, fixed platforms, and subsequent handheld camera technology, Denis Cosgrove and William Fox then explain how military (...) reconnaissance and governmental projects were instrumental in catalyzing these and other innovations in the field. They examine pivotal historical moments in which aerial photography began to establish itself as essential tool, such as in World War II military strategies, high-altitude photography taken from postwar rockets and aircraft, and the use of aerial photography during the cold war and the Cuban Missile Crisis. The book also explores the advancement of geographic scholarship through aerial photography, ranging from military excursions into Antarctica to the images of the curvature of the earth taken during the Apollo space missions. While digital technology and remote sensing have changed the landscape of photography, Photography and Flight argues that they have not diminished the significance of aerial photography in providing images of the earth. Rather, new technologies and resulting innovations such as Google Earth have enabled the mass democratization of access to such information. Photography and Flight ultimately reveals how the camera lens from far away continues to unearth telling details about the land and those who live upon it. (shrink)