Cauliflower mitochondria

This reaction has not yet been satisfactorily demonstrated in plants. Moore (1974) did not detect BPG when studying PG biosynthesis in castor bean endosperm mitochondria. Douce and Dupont (1969) found traces in their experiments with cauliflower mitochondria, and these experiments suggest that BPG biosynthesis could be characterized if this specific problem were tackled. 

Fig. 4. C-labeled lipid exchange in vitro between microsomes and mitochondria from two different species, (a) Labeled mitochondria from potato (Mit p.) mixed with cauliflower microsomes (Mic ch.) in cauliflower cytoplasmic supernatant (Sum ch.). (b) Labeled mitochondria from cauliflower (Mit ch.) mixed with potato microsomes (Mic p.) in potato cytoplasmic supernatant (Sum p.). (c) Labeled microsomes from potato (Mic p.) mixed with cauliflower mitochondria (Mit ch.) in cauliflower cytoplasmic supernatant (Sum. ch.). (d) Labeled cauliflower microsomes (Mic ch.) mixed with potato mitochondria in potato cytoplasmic supernatant (from Ben Abdelkader and Mazliak, 1970).

Fig. 5. Transfer of radioactive lipids from liposomes to cauliflower mitochondria. Radioactively labeled liposomes were incubated with cauliflower mitochondria, and after various incubation periods the radioactivity in the mitochondria per milligram of protein was determined. Two experiments were carried out in the first (lower curve) 0.56 x 10 dpm in the liposomes was offered to 3.9 mg of mitochondrial protein, while in the second (upper curve) 3.6 X 10 dpm in the liposomes was offered to 2.1 mg of mitochondrial protein. The inset gives the plot of the percentage of the initial radioactivity recovered in the mitochondrion versus time, in the same two experiments (from Douady and Mazliak, 1975).

Most authors find sterols of all forms to be particularly abundant in ER (Table V). It should be realized that in animal tissue the cellular membranes richest in cholesterol are the plasma and lysosomal membranes. Further fractionation of plant membranes may reveal a high content of sterol derivatives in plasma membrane, tonoplast, and other membranes. Duperonet al. (1975) measured the sterol content of cauliflower mitochondria and found that the inner membrane contained 28 pg sterol per milligram of protein and the outer membrane 77 p,g sterol per milligram of protein. This enrichment in the outer membrane is also found in animal mitochondria. 

Plasma membrane (potato) Mitochondria (cauliflower) Mitochondria (sycamore) Peroxisome (potato) Peroxisome (castor bean) Microsomal (potato) Microsomal (pea)... 

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