Chloroplasts structure

These extensive alterations in cell structure and the biochemical machinery are indicative of entry into an ametabolic condition. In this condition damage from free radicals is potentially decreased, certainly the loss of chlorophyll and chloroplast structure removes a major source of free radical generation. About 50% of the extremely desiccation tolerant monocots exhibit extensive loss of chlorophyll and ultrastructural organisation when desiccated. Dicots, ferns and bryophytes retain most of their chlorophyll and exhibit small changes in structure when dry (see Gaff,... 

Chloroplast—Structure in green plant cells that captures light energy and converts it into chemical energy. 

Shimokawa e t a l. ( 16 ) examined the changes in chloroplast structure induced by ethylene in satsuma mandarin. Electron micrographs showed peel of ethylene-treated fruit had fewer chloroplasts and of smaller size. The inner membrane system of the chloroplasts was found to disintegrate prior to the breakdown of other cell structures. 

Calera, M., Mata, R., Lotina-Hennsen, B., Anaya, A.L. Uncoupling behavior ofthe4-phenylcoumarins in spinach chloroplasts- Structure-activity relationships. J Agr Food Chem 1996 44 2966-2969. 

Staehelin, L.A. (2003) Chloroplast structure from chlorophyll granules to supra-molecular architecture of thylakoid membranes. Photosynth. Res., 76,... 

Kirchanski, S.J. and Spencer, D. (2004) Chloroplasts in living cells and the string-of-grana concept of chloroplast structure revisited. Photosynth. Res., 80, 345-352. 

Simeonova, E., van Hasselt, P.R., Dobrucki, J. and Mostowska, A. (2005) Light-dependent reversal of dark-chilling induced changes in chloroplast structure and arrangement of chlorophyll-protein complexes in bean thylakoid membranes. Biochim. Biophys. Acta, 1710, 13-23. 

Gergis, M.S. (1972) Influence of carbon dioxide supply on chloroplast structure of Chlorella pyrenoidosa. Arch. Mikrobiol., 83, 321-327. 

If a rapidly growing photosynthetic cell such as an alga cell is exposed to C 02 for 1 to 2 minutes and then killed, as much as 30% of the radioactive compounds formed behave as lipidlike substances when partitioned between aqueous and organic solvents. A considerable portion of the chloroplast structure consists of lipid materials, and rapid lipid synthesis is required for chloroplast growth and division. 

Jasmonic acid treatment has been reported to result in the inhibition of Hill reaction activity and flash-Oj evolution [73], alteration of intra-chloroplast structure [74] and chlorophyll fluorescence parameters [75], a change in the polypeptide pattern of thylakoid membrane proteins [76] and ultimately a decreased photosynthetic rate [77]. An increase in the rate of dark respiration, photorespiration and stomatal resistance to COj diffusion has also been observed [77,78]. 

Thiolactomycin (TLM) selectively Inhibits type 11 fatty acid synthases from E. coli and higher plants, but does not type 1 fatty acid synthases from Tungi and nKunmals. In this paper, the effect of TLM on fatty acid synthesis is confirmed in enzyme and cell levels. Pulse- and chase-experiments with plant tissues in the presence of TLM accounts for the controlled synthesis of lipids in higher plants. Finally the modulated lipid composition of plant tissues by continuous administration of TLM is examined in relation to the chloroplast structure and the photosynthetic activity of the tissues. 

Fig. 5 shows the structure of Avena and Brassica chloroplasts formed from etioplasts in the presence of TLM. Avena chloroplasts turned from elipse into round shape, suggesting a change in permeability of the envelope membrane. The thylakoid membranes of Brassica chloroplasts were swollen everywhere, leading to loose stacking o7 thylakoids. Thus, insufficiency of MGDG and/or PG induced the membrane transformation of the chloroplast. However, the photosynthetic activites in TLM-treated Avena and Brassica leaves as measured by 2 evolution decreased only a little, in spite of visible changes of the chloroplast structure (data not shown). 

Other laboratories have also carried out simultaneous measurements of the lipid or lipid metabolism changes associated with pyridazinone-induced in plastid morphology. Davies and Harwood examined the effects of Sandoz 6706 and Sandoz 9785 on lipid metabolism and membrane structure in greening barley. Changes seen in chloroplast structures included a slowing of normal differentiation on greening and the appearance of large... 

Anderson JM Goodchild DJ and Boardman NK (1973) Composition of the photosystems and chloroplast structure in extreme shade plants. Biochim. 

Steinbeck KE Burke JJ and Amtzen CJ (1979) Evidence for the role of surface-exposed segments of the light harvesting complex in cation-mediated control of chloroplast structure and function. Arch. Biochem. Biophys. 195, 546-557. 

Shavit N (1980) Energy transduction in chloroplasts Structure and function of the ATPase complex, Annu. Rev. Biochem. 49, 111-138. 

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