These results indicate that oil-droplets of oleaginous tissues correspond to spherosomes of nonoily tissues. Therefore, both types of particles should be referred to by the same name. Since these particles are rich in lipids, it is suggested that the name "spherosome" be abandoned in favor of "oleosome," which is also entitled to priority.Spherosomes are intracellular particles which have been familiar to botanical cytologists for more than half a century; yet, surprisingly, they are still the object of much controversy (4,5,7,8,10,13,16,19,23). The term "spherosome" was introduced into the literature in 1922 when Dangeard (2) distinguished between spherical (spherosomes) and rodshaped (mitosomes) "microsomes of the spherome." Earlier, Dangeard (1) had described the spherome as consisting of "microsomes" which he reported as highly refringent spherules of an oily appearance that blacken, more or less, with osmic acid. From the very outset, there was controversy concerning spherosomes: one faction (1) which looked on spherosomes as organelles, and the other (6) which considered spherosomes merely as products of cellular metabolism (lipids).One of the most recent eruptions of this controversy was the objection voiced over the identification of "oil-droplets" from oleaginous tissues with "spherosomes" of nonoily tissues (19). Oil-droplets were purported to be droplets of oil that were free in the cytoplasm without delimiting unit-membranes, whereas spherosomes were alleged to be composed of phospholipids and proteins which were bounded by unit-mem- Electron-microscopic Procedures. Electron microscopic examinations were conducted on tissues: (a) fixed overnight at room temperature in 2% osmium tetroxide dissolved in 0.1 M phosphate buffer, pH 7.2, (b) fixed for 1 hr in 2% aqueous potassium permanganate at room temperature, and (c) doubly fixed with aldehyde and osmic acid fixatives. The tissue was first fixed overnight in an aldehyde fixative which consisted of 2.8% glutaraldehyde and half-saturated picric acid adjusted to pH 7.3 with 50 mm sodium cacodylate. Isolation of Spherosomes. Basically, spherosomes were isolated from tissue homogenates by differential centrifugation. Fifty pounds of onion bulbs (Allium cepa L.) were sliced into small pieces and blended in a Waring Blendor with approximately an equal volume of 0.5 M NaCl containing 50 mM tris-HCl buffer, pH 7.2. The mixture was blended for 1 min in an ice bath. The homogenate was squeezed through eight layers of cheesecloth, and the effluent was passed through a Sharples Type T-41-248RY-34 continuous-flow centrifuge at 20,000g to remove dense particles. The supernatant was then passed through a De Laval Gyro test unit separator to collect particles less dense than the grinding medium. No "cream" was collected from the separator; however, a light layer of creamy substance adhered to the cones inside the separator. This mate-675 www.plantphysiol.org on May 11, 2018 -Published by Downloaded from

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The lipid‐free residue of lipid body membranes was isolated from quiescent peanuts and was physicochemically characterized. The preponderant component of the residue was proteinaceous and consisted of at least two polypeptides according to ultracentrifugation, gel filtration, gel electrophoresis and HPLC. The molecular weight of the principal polypeptide was between 10,000 and 16,000 daltons. Only one antigen, immunochemically unique with respect to other peanut components, was detected. Spectral analyses indicated the presence of a protoheme and revealed conformational modes of β‐sheet and unordered structure but no α‐helix. The amino acid composition was similar to that of an integral membrane polypeptide rather than to those of peripheral membranes or other plant polypeptides. The hydrophobicity, conformation and quantitative content of polypeptides were suitable for the existence of a monolayer at the lipid body‐cytoplasm interface. The results indicated that lipid body coatings physicochemically resemble membranes of intracellular organelles and supported the morphological concept that the coatings are half‐unit biological membranes. Reutilization of lipid body membranes appeared possible after lipid depletion during seed germination.

Hexane and mixtures of hexane and 2-25% acetic acid (v/v) were used to prepare oil and protein from glanded cottonseed by solvent extraction. As the amount of acetic acid in the solvent increased, the amounts of total lipid, phospholipid, neutral oil, and gossypol in each miscella increased, but the amount of free fatty acids did not change significantly. However, the solubility of protein in 0.02 N NaOH decreased as the amount of acetic acid in the solvent used to prepare each meal increased. Other aspects of using acidified hexane are described.

Hexane and hexane containing 5% acetic acid (v/v) were used to extract lipids from soybean at room temperature and at 60 C. Hexane/acetic acid extractions yielded ca. 11% more total lipids and ca. 6-10% more neutral oil than did hexane extractions. Hexane/ acetic acid extraction at room temperature yielded the same or slightly more neutral oil than did hexane at 60 C. Thirty-five times more phosphorus was extracted with hexane/acetic acid than with hexane; this phosphorus represented ca. 46% of the phospholipid phosphorus of soybeaia. Also, when hexane/acetic acid was used as the solvent, the separation of miscella from marc by filtration was about twice as rapid as the separation when hexane alone was the solvent.