Membrane-bound bicarbonate is believed by some to act as an essential activator of photosystem 2 (PS2) electron transport. Formáte and other inhibitory monovalent anions act by removing bound-bicarbonate. This belief relies to a great extent on the observation that formáte (100 mM) pretreated thylakoids exhibit a non- proportionality between Hill activity (HAR) and chlorophyll (Chl) concentration when preirradiated with bright radiation in reaction mixture that contains only 5 mM formáte. The non-linearity was attributed to a supposed loosening of residual bicarbonate still present after formáte treatment and which would be more abundant at higher Chl concentrations. In repeating this experiment, we observed an increase in HAR at higher Chl concentrations in preirradiated, but also in non-preirradiated samples, the latter were simply left in the dark for 3 min before measurements were made. Therefore, preirradiation is not needed to restore some HAR in formáte pretreated samples; a 3 min wait in the electrode chamber at low formáte concentration is sufficient to partially relieve the formáte inhibition of PS2 activity. Moreover, HAR in samples preirradiated by weak radiation, or not preirradiated at all, was directly proportional to Chl concentration. We can attribute the increase in activity to a dissociation of bound formáte, not necessarily to the effect of residual bicarbonate. Non-linearity in HAR with Chl concentration was found only in high- irradiance pretreated samples. We can attribute this to a greater amount of photoinhibition occurring in the dilute samples, where the effective irradiance was greater. There is no need to postuláte the existence of residual bound bicarbonate to explain these results.
This article examines whether there are any differences in the way in which married couples and unmarried cohabitating couples manage their incomes. Using data from the ISSP 1994 and the ISSP 2002 the author attempts to answer the question of whether over the course of the 1990s in the Czech Republic the character of unmarried cohabitation changed, and whether the economic arrangements of unmarried couples with children resemble those of married couples. Crosstabulation indicates that unmarried couples manage their respective incomes separately more often than married couples do. However, if we take into account the different socio-demographic and socio-economic structures of these couples, the differences in income management connected with marital status vanish. The results of a logistic regression show that separate financial management occurs more often among childless couples, people less satisfied with their family life, and those who have experienced the break-up of a partnership before. In the case where an unmarried couple is raising children, the household income arrangement of the partners is similar to that of married couples.