Maize lipid bodies

The membrane proteins of maize lipid bodies have been subjected to intensive studies (14). By SDS polyacrylamide gel electrophoresis (Figure 1), the proteins are resolved into several major protein bands, three of low Mr s (19,500, 18,000, and 16,500), and one of higher Mr (40,000). The low Mr proteins have alkaline pi values, and behave as hydrophobic integral proteins, as shown by their resistance to solubilization after repeated washing, amino acid composition, and partitioning in a Triton X-114 system. 

SYNTHESIS AND DEGRADATION OF LIPID BODIES IN THE SCUTELLA OF MAIZE... 

Using the scutella of maize, our laboratory has been studying the synthesis and degradation of the lipid bodies during seed maturation and germination. In order to delineate the mechanism of deposition and utilization of triacylglycerols in the lipid bodies, we study the last... 

Fig. 1. Left panel SDS-polyacrylamide gel of total homogenate, isolated lipid bodies, and isolated L-3 protein (Mr 16,500) of maize scutella. The positions of Mr markers are shown on the left. Right panel Blotting of SDS polyacrylamide gel of total scutellum homogenate. After blotting, the strip was stained for protein or allowed to react with antibodies (+AB). (14)...

In subcellular fractionation of the storage tissues of many germinated seeds, the lipase activity Is present either In the soluble fraction or associated with the membranes of the lipid bodies (see reviews, 18,19). In seeds where the lipase Is found In the soluble fractions, the enzymes In vivo will still have to come In contact with the membrane of the lipid bodies during catalysis. In those seeds where the lipase Is associated with the membrane of the lipid bodies, the enzyme may be loosely (e.g., rapeseed, mustard seed) or tightly (e.g., castor bean and maize) associated with the organelles. 

Fig. 3. Electron micrograph of a portion of a scutellum cell of 6-day-old maize seedling, showing the fusion of degrading lipid bodies and the cell vacuoles. L, lipid body V, vacuole. (23)...

Fig. 4. Schematic Illustration of the synthesis and degradation of a lipid body In the maize scutellum during seed maturation and germination. See text for explanation. RER, rough endoplasmic reticulum FA, fatty acid tri, trlacylglycerol, PL, phospholipid free, free polyribosomes.

The minimum position depends on both the seed type and the seed state. Among the species studied, T2 measurements distinguished two categories of seeds pea (r2=1.1 and 45 ms), maize (1.2 and 60 ms), and wheat (1.3 and 30 ms) for which two components of T2 were observed, and lettuce (103 ms), tomato (98 ms), and radish (85 ms), which presented one single component (Pouliquen et al. 1997). The main short component was attributed to water (Ti.T2 ratio is very high, which suggests that these protons are in a near-solid state at T=39°C, i.e., this water is SBW) whereas the long one was attributed to lipids from oil bodies (T. T2 is close to 1, which means that the protons... 

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