Current Phycology – serie
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534 kr
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Ralph A. LewiQand Lanna Cheng In physics, the discovery of new (more properly, hitherto undetected) particles has often resulted from a search: like the discovery of America, their existence had been postulated but their actual existence awaited confirmation. In biology, new discoveries are rarely made in this way. The existence of an alga like Prochloron, as a putative ancestor of chloro plasts, had been postulated, but in fact its discovery was a consequence of fortuitous events. Green algal symbionts in didemnid ascidians had been known for decades to a few marine zoologists who had worked in coral reef areas, but nobody had bothered much about them. When we happened to find them, under boulders on a seashore in Baja California, Mexico, where we were taking part in a student expedition, we didn't bother much either at first, though they worried us a little. With our portable microscope we could see no nuclei in the cells, which, according to the dogma accepted at the time, indicated that they were blue-green algae-yet they didn't look blue-green. They were leaf-green, like green algae and higher plants. We made desultory attempts to grow them in culture, in variously enriched seawater media, but failed. (This proved to be a frustrating experience, all too frequently repeated on subsequent expeditions. ) We collected enough for electron microscopy, though, and transmission electron microscopy (TEM) studies indicated that the cells were unequivocally prokaryotic.
527 kr
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Algae exhibit the greatest variety of cell motility phenomena in the living world. These range from the peculiar gliding motility of filamentous blue green algae or cyanobacteria to chloroplast movements and cytoplasmic streaming which are most common in higher plants. In addition, cell motility by eukaryotic flagella is the characteristic mode of cell locomotion in algal flagellates and most reproductive cells of algae. Algae use these cell motility systems mainly to orient themselves or their photosynthetic organelles in a suitable light gradient to optimize growth and reproduction. In consequence most of the motility systems are coupled to photoreceptors and are regulated by signal transduction cascades. Algal cell motility has thus attracted consid erable interest also from non-phycologists and some algal motility systems have become models of research in cell and molecular biology. This book summarizes some of the progress that has been made in recent years in the analysis of cell motility phenomena in the algae. Although complete coverage of the subject was not attempted, the six chapters cover all the major types of cell motility systems and the authors provide in depth reviews of gliding motility, chloroplast movements, cytoplasmic streaming, flagellar beat pat terns, mechanisms of flagellar movement and centrin-mediated cell motility.