Larval and early post-larval growth has been investigated in Hyas araneus L. (Majidae) reared in the laboratory. Growth was measured as dry weight (DW), ash-free dry weight (AFDW), carbon (C), nitrogen (N), hydrogen (H), gross biochemical constituents (protein, lipid, carbohydrate, chitin, ash) and energy (calculated separately from carbon and biochemical composition). During larval development, i. e. from freshly hatched zoea-1 to late megalopa, all these cr~teria of b~omass increase by factors ranging between 5 and 14; carbohydrate shows the lowest, chitin the highest Increment. There are indications of loss in organic body weight during the latest period preceding metamorphosis to the crab stage. When no food is offered during this time, megalopae lose significantly more biomass than control larvae. This suggests that food is still required, but feeding activity is reduced to a level below maintenance ingestion rate. Follow~ng metamorphosis, the juvenile crab accumulates biomass at a far higher absolute rate (expressed as pg d-') than all larval stages. This alteration in growth pattern is attributed to lack of further morphological changes. Among the biochemical constituents, protein is most prominent (50 to 68 % AFDW), followed by lipid (I? to 30 %) and chitin (7 to 17 76). Carbohydrates play a minor role contributing only 1 6 to 3.7 % of AFDW. The percentage of protein increases during zoeal development; later it decreases. This pattern is inversely related to changes in ash content, which ranges from 19 to 30 % DW. Lipid (% AFDW) shows a decreasing tendency during larval development. Separate calculations of energy content from C and from biochemical composition yield systematic differences, the former usually being lower than the latter. Only in late megalopae is this pattern Inverted, presumably due to inorganic C in the increasingly calcified cuticle of this stage. Non-linear regression equations are given for conversions of C to protein, lipid, and carbohydrate, N to protein, and H to lipid. The relationship between N and protein suggests that non-protein, non-chitin N may also be important, and calculation of protein by multiplication of total N X 6.25 results in an overestimation of protein.

The effects of disalicylidenepropanediamine (DSPD) and disulfo-disalicylidenepropanediamine (sulfo-DSPD) on the photosynthetic electron transport of isolated chloroplasts have been reexamined.Our data suggest that DSPD, but not sulfo-DSPD, is an effective inhibitor of electron transport between photosystem II and photosystem I before or at plastocyanin. Furthermore, both DSPD and sulfo-DSPD block electron transport at the site of ferredoxin.Under certain conditions DSPD and even more so sulfo-DSPD function as autooxidizable electron acceptors.Finally it is shown that DSPD can cause an inhibition of photophosphorylation.According to our results the use of DSPD as a specific inhibitor of ferredoxin-dependent reactions has to be questioned.In 1967, disalicylidenediamines were introduced by Trebst and Burba (23) as inhibitors of photosynthetic electron transport.DSPD' and sulfo-DSPD were the main representatives of this new class of inhibitors. The site of inhibition of photosynthetic electron transport by these compounds was localized at ferredoxin by studying the effect of sulfo-DSPD on broken chloroplasts (23). The other compounds were thought to act in the same manner. Inasmuch as only the lipophilic DSPD is able to enter intact chloroplasts or cells, only DSPD was used in in vivo experiments. It has been assumed that DSPD acts at the same site as sulfo-DSPD, ie. as an antagonist of ferredoxin (1, 5-7, 9, 12-16, 20, 21, 23, 26-29). We also tried to study the role of ferredoxin in photosynthetic reactions with the aid of DSPD. We found, however, that DSPD, unlike sulfo-DSPD, inhibits photosynthetic electron transport between PSII and PSI and that it also inhibits photophosphorylation. plasts were washed once in the suspending medium. Both the suspending medium and the basic reaction medium for the experiments with broken chloroplasts (solution B) were identical to solution A, but contained 0.05 M Hepes-NaOH (pH 7.6) instead of Mes buffer. An aliquot of 0.1 ml of the chloroplast suspension was added to 0.95 ml of water at 0 C to prepare broken chloroplasts. After about 1 min, 0.95 ml of double strength solution B was added and the broken chloroplasts were used at the final concentrations described below. MATERIALS AND METHODSFor 02 evolution or uptake, which was measured polarographically with a Beckman electrode, broken chloroplasts at a concentration equivalent to 50 ,ug Chl/ml were used. The test cuvette (total volume 2.0 ml) was fitted with a water jacket and a magnetic stirrer. Illumination was provided by a slide projector. The intensity of white light was about 500 w/m2 and the temperature was kept at 18 C. NADP Illuminatioh (about 500 w/m2) was provided by 60-w Krypton lamps from the bottom of the water bath. Incorporation of 32Pinto organic compounds was measured after isobutanol-benzene extraction (4) in a liquid scintillation counter.Chl was measured according to Arnon (2). RESULTS Noncyclic electron flow from water to ferricyanide is thought to occur via both photosystems, at least if fresh...

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