Quantitative correlation of peripheral and intrinsic core polypeptides of photosystem II with photosynthetic electron-transport activity ofAcetabularia mediterranea in red and blue light

The high photosynthetic activity (O₂ production and CO₂ consumption) ofAcetabularia mediterranea Lamour. (=A. acetabulum (L.) Silva) characteristic of cells cultured in white light decreases slowly when cells are kept in continuous red light, and is less than 20% of the original activity after three weeks. Subsequent blue irradiation restores the original activity completely within 3–5 d. The polypeptide composition of the thylakoids from cells grown in either red or blue light and after transfer from red to blue light was analyzed mainly with regards to photosystem II (PSII). The P700-containing reaction-centre complex of photosystem I, CPI, showed only minor quantitative alterations as a consequence of the growth-light quality, which correlated well with the activity of photosystem I under these conditions. In PSII, no drastic changes occurred in the quantity of the reaction-centre components D1 (herbicide-binding polypeptide) and D2, as determined by immunoblots. Likewise, the proteins associated with the water-splitting apparatus did not change detectably in thylakoids from red- or blue-light-treated cells (the 16-kDa component could not be found inAcetabularia thylakoids). The level of the major light-harvesting complex was completely unaffected by the light quality. In contrast, the quantities of the chlorophyll a-protein complexes of the core antenna, CP43 and CP47 (and probably CP29), changed, with kinetics similar to those of total photosynthetic activity. We postulate that the function of the PSII antenna became increasingly impaired in the absence of blue light (i.e. in red light), while blue light had a restoring effect. The peripheral antenna, comprising the light-harvesting complexes, is probably functionally connected with the reaction-centre chlorophylls via the core antenna chlorophyll-protein complexes (CP43, CP47 and probably CP29). A deficiency of these complexes would lead to uncoupling of antenna and reaction centre in the majority of PSII complexes after long periods of red-light treatment.     

Effect of folic acid deficiency upon lymphocyte subsets from lymphoid organs in mice.

1. Three groups of weanling C57BL/6 female mice were fed one of two folate-deficient diets (0 and 0.1 mg folic acid/kg diet) or a normal folate-containing diet (2 mg folic acid/kg diet) for 8 weeks. A control pair-fed group was introduced with the most severe folate-deficient diet. Seven mice were fed the 0 mg folic acid/kg diet for 8 weeks, then rehabilitated (R) on the 2 mg folic acid/kg diet for 10 days. 2. Mice fed 0 mg folic acid/kg diet were severely folate-deficient (SFD), whereas mice fed 0.1 mg folic acid/kg diet were moderately folate-deficient (MFD), as shown by their folate status parameters. 3. Thymus weight, thymocyte content and positive immature CD4+8+ cells were decreased in SFD mice compared to controls. These values were normalized after 10 days of rehabilitation. 4. Mesenteric lymph node cells were apparently not affected by folate deficiency. 5. The proportion of Thy-1+ splenocytes was mildly lower in SFD mice than in controls. In R mice, mean spleen weight and spleen cellularity were increased compared to the other groups, but the proportions of Thy-1+, CD4+8- and CD4-8+ cells were markedly lower than control values.     

Der Wasserhaushalt vonAvena sativa L. bei steigender Mineralvolldüngung

Zusammenfassung 1. Die Beeinflussung des Wasserhaushaltes durch gesteigerte Mineralvolldüngung wurde an Freilandkulturen von Avena sativa L. untersucht.2. Durch die Düngung bildeten sich Unterschiede im Bestandsklima aus, die bereits inmitten der nur 2,5 m² großen Versuchsparzellen zur Geltung kamen. Sie ließen sich variationsstatistisch erfassen und absichern. Die Luft blieb im Bestand mit höherer Düngung kühler und feuchter.3. Das üppigere Wachstum gedüngter Kulturen erhöhte den Wasserverbrauch pro Flächeneinheit und führte damit zu einer Erniedrigung des Bodenwassergehaltes, die größer als unter ungedüngten Kulturen war.4. Gedüngte Haferpflanzen wiesen einen höheren Wassergehalt und ein höheres Wassersättigungsdefizit am Mittag auf.5. Ansteigende, jedoch das Optimum nicht überschreitende Düngung bewirkte eine Herabsetzung der Transpiration (pro Gramm Frischgewicht).

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Summary 1. The effect of increasing amounts of mineral fertilizers on the plant-water relationship of Avena sativa L. was analysed in field trials.2. As an effect produced by different grades of fertilization different microclimates in the stands have been established even in small plots of only 2.5 m². The air in the stands with higher fertilization was cooler and moister.3. The more vigorous growth on fertilized plots increased water consumption per area and consequently decreased the water content of the soil.4. Water content and water deficit of leaf laminae were higher in fertilized than in not fertilized plants.5. Increasing amounts of fertilizers not transgressing the optimum caused a decrease of transpiration (per gram fresh weight).

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Teil einer Dissertation an der Naturwissenschaftlich-Philosophischen Fakultät der Justus Liebig-Universität Gießen