Kinetics of non-photochemical reduction of the photosynthetic intersystem electron transport chain by exogenous NADPH was examined in osmotically lysed spinach chloroplasts by chlorophyll (Chl) fluorescence measurements under anaerobic condition. Upon the addition of NADPH, the apparent F0 increased sigmoidally, and the value of the maximal slope was calculated to give the reduction rate of plastoquinone (PQ) pool. Application of 5 µM antimycin A lowered significantly both the ceiling and the rate of the NADPH-induced Chl fluorescence increase, while the suppressive effect of 10 µM rotenone was slighter. This indicated that dark reduction of the PQ pool by NADPH in spinach chloroplasts under O2-limitation condition could be attributed mainly to the pathway catalysed sequentially by ferredoxin-NADP+ oxidoreductase (FNR) and ferredoxin-plastoquinone reductase (FQR), rather than that mediated by NAD(P)H dehydro-genase (NDH). and Ming-Xian Jin, Hualing Mi.
The possible formation of a new stellar generation may be seen in the bright rimmed dark clouds that surround the giant HII region IC 1396. A well.defined ring of IRAS point sources is projected near the ionisation front indicated by the bright rims. We sugest that some of these sources are young stellar objects, and the majority represents density enhancements in the shocked neutral gas layer preceding the ionisation front which might eventually become stars.
A new method to investigate periods and their variations is proposed. The phase curve is approximated by the cubic
spline-functíon with fixed number of equidistantly distributed in phasev characteristic points. Because such a smoothing function depends on the value of the Inltial epoch it is proposed to use the mean of some spline-curves corresponding to various initial epochs for the approximation. The mean guadratic deviation of observatlons from this best fit curve serves as the test function. The best fit phase deviations of the 'season sets’ of observations are used to study period variations.