It is also possible that contractile vacuoles originate by some form of phase separation not yet understood and possibly involving the contractile properties of proteins, and' it is possible that this process continues to operate in the walls of the vacuoles or feeder canals. This secretory process may be the function of that part of the vacuolar apparatus which blackens on impregnation with osmic acid, and which seems to possess some degree of permanence from vacuole to vacuole and in some cases from parent to daughter cell. Remarkably little is known about the mechanism of systole. General body turgor may contribute, but it is not essential. In ciliates the main force is local and probably comes from a tension in the wall of the vacuole itself, but it is not known whether or not this is an active contraction of an oriented protein layer. The critical process for the initiation of systole is probably the opening of the pore. It is possible that in ciliates there is a rhythmically operating independent timing mechani,sm by which the vacuolar cycle is controlled, but its existence has not been demonstrated.

Cet ouvrage illustre de façon claire et pédagogique les méthodes et les concepts qui sont à la base des progrès de la génomique en biologie végétale (grands programmes internationaux de séquençage, outils de la bio-informatique, méthodes d'analyse de l'expression des gènes incluant leurs produits métaboliques finaux et leur spécificité tissulaire et/ou cellulaire). Il rend compte des applications potentielles de la génomique dans les domaines de la génétique et de l'amélioration des plantes, de l'écophysiologie et de l'agronomie. Ce livre s'adresse aux étudiants de fin d'études universitaires ou agronomiques, aux professeurs de l'enseignement supérieur, aux techniciens, aux ingénieurs et scientifiques qui souhaitent acquérir des connaissances en génomique végétale.

Zytologie.