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Antibodies against the individual subunits of protein complexes in the chloroplast membranes were used to follow the amounts of these polypeptides during foliar senescence. No change was found in the amount of polypeptides of photosystem I reaction center and the chloroplast coupling factor during senescence of oat (Avena sativa L.) and bean (Phaseolus vulgaris L.) leaves. A significant decrease in the amount of the different components of the cytochrome b6-fcomplex was detected. This change may account for the decrease in the rate of electron transport, which might be the rate limiting step of photosynthesis in senescing leaves.sity of illumination employed for 12 h/d was about 1.5 x 103 erg/cm2.s. Primary leaves were harvested after full expansion was achieved (15 and 8 d after sowing bean and oat seeds, respectively).Controlled Facilitated Senescence. Three-cm-long segments were cut off the tips of 8-d-old oat leaves, and then incubated on wet gauze for 4 d at 24C in the dark. Foliar senescence is characterized by a major change in the chloroplast structure and function (2, 5). Most studies on senescing chloroplasts were based upon in vitro measurements of partial photosynthetic reactions. Examples are CO2 fixation (7, 11), photophosphorylation (11, 13), Hill reaction (10), and electron transport through PSI and PSI1 (4,7,13,14,19). Although a decrease in the rate of some of these reactions was demonstrated, there was no definite identification of a change in a specific site(s) that might limit the rate of photosynthesis during senescence.Electron microscopy revealed a decrease in plastid volume (2) and a disruption ofthe internal membrane system in chloroplasts from senescing leaves (5). Biochemical studies showed that along with these morphological changes, there is a change in the lipid composition of the membranes during senescence (2). These findings may imply that the changes in structure and physical properties ofthe thylakoid membranes coincide with the decrease in the rate of photosynthetic activity. In the present study, an immunological approach was applied in order to follow the changes in the relative amounts of some of the chloroplast membrane protein complexes during senescence. MATERIALS AND METHODS

Public Health Laboratories (PHL) as part of Public Health Services are involved in law enforcement and ensuring food and water quality. The laboratories had to go through an organizational and monetary change imposed by the growing and changing needs of the state of Israel. The laboratories had to become more modern and to implement new and more sophisticated testing methods. Another requirement was to perform a steadily increasing number of tests and to be more flexible towards customers' demands. Yet, the budget was not changed accordingly, as the Public Service to which the laboratories belong to do not respond to changing needs. Management realization was that the accreditation process could be used as a tool to achieve organizational and cultural change. Understanding and transformation were required throughout the organization, including management. Proficiency testing is performed for all testing methods in all areas even for non-accredited tests such as clinical tests. Proficiency testing was used as a tool for organizational culture change. It is a great index with