Reactions of aldehydes with unsaturated fatty acids during histological fixation

Jones, Dennis

doi:10.1007/978-1-4899-3260-0_1

Cited by 5 publications

(5 citation statements)

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“…Thus if the lipids present v^'ere removed durmg dehydration and replaced by resin, and provided that proteins retain their position and shape, the membrane would be represented by these remaining structures. However, there is some evidence that aldehydes may modify fatty acids (Jones, 1973). While there will always be some measure of uncertainty about interpreting such images, particularly the interactions of fixatives and resins on the membrane phospholipids, evidence from X-ray diffraction studies supports the view that the membranes of dry seeds are in a lamellar state (McKersie & Stinson, 1980;Seewaldt et al, 1981).…”

Section: Discussionmentioning

confidence: 99%

“…Since the use of formalin vapours is a standard procedure for the fixation of freeze-dried tissues in animal histological techniques (Pearse, 1980), both paraformaldehyde and acroJein were explored as possible fixatives. Neither of these compounds are regarded as suitable fixatives for Jipids, although it should be noted that calcium-formal is used as a fixative for histochemical localization of lipids (Pearse, 1980); evidence also exists for chemical interactions between unsaturated fatty acids and formaldehyde (Jones, 1973). Osmium tetroxide reacts with the unsaturated double bonds of fatty acfds and is regarded as both a fixative and stain of lipids (Hayat, 1981).…”

Section: Vapour Fixation Techniquesmentioning

confidence: 99%

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Studies on the anhydrous fixation of dry seeds of lettuce (Lactuca saliva L.)

Smith

1991

New Phytologist

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SUMMARYA number of fixation techniques were used on cubes of dry cotyledonary tissue of lettuce seed to develop a satisfactory technique for the anhydrous fixation of dry seed material for electron microscopy. Fixation with formaldehyde or acrolein vapours in combination with Spurr's resin embedding produced satisfactory sections, while protocols involving the use of osmium tetroxide vapours resulted in brittle specimens that were difficult to section. The use of glycerol as a vehicle for anhydrous aldehyde fixation, followed by subsequent aqueous processing, introduced artifacts in membrane uitrastructure. When model phospholipid systems, known to exist in the hexagonal phase, were prepared for electron microscopy and compared with anhydrously fixed cotyiedonary tissue, the results suggested that dry seed membranes exist in a lamellar phase. It is proposed that leakage from imbibing seeds may be the result of physical/molecular changes in the membranes rather than of a phase change from the hexagonal to the iamellar state.Key words: Lactuca sativa, anhydrous seed fixation, uitrastructure, aldehyde vapour, osmium tetroxide, hexagonal-lamellar membranes, imbibitional leakage. INTRODL'CTIONWater uptake by the imbibing seed is characterized by a stage of rapid water uptake, followed by a slower rate of uptake until full hydration is achieved (Simon & Raja Harun, 1972;Leopold, 1980; Murphy & Noland, 1982). Although the leakage of solutes from imbibing seed tissues was initially explained as the result of a phase change in membrane phospholipids from a hexagonal to bilayer state (Simon, 1974), this proposal has not been supported by more recent studies (McKersie & Stinson, 1980;Seewaldt et aL, 1981;Leopold & Vertucci, 1986). It had been suggested that peroxidative changes in seed membranes in dry storage could exert a profound effect on the membrane biJayer at imbibition (Villiers, 1973(Villiers, , 1980Simon 1974). This study reports on attempts to devise a satisfactory method for the electron microscope visualization of cytoplasmic organization and, more especially, the membrane structure of dr>^ seeds. Although there have been many ultrastructural studies on dry seeds in the past (Perner, 1965;Thomson, 1979;Opik, 1980Opik, , 1985Yatsu, 1983), these studies were not specifically aimed at the phase structure of membranes. Furthermore, a recent study (Crowe, Hoekstra & Crowe, 1989) has again suggested that membrane phase transitions are responsible for imbibitional damage in dry pollen. Thus the development of an optimal technique for examining membrane uitrastructure in dr\' seeds is particularly pertinent. MATERIALS AND METHODS Plant materialSeeds of lettuce {Lactuca sativa L. cv. Great Lakes) were purchased from a local supplier. Transverse slices of cotyledonary tissue were made with singleedged shaving blades (Schick) which were then cut into cubes of predonninantly uniform tissue of less than 0-5 Aqueous fixationTissue cubes were placed in 5 "" phosphate-buffered gJutaraldehyde (pH 7-4) for 30 min and brief...

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Section: Discussionmentioning

confidence: 99%

Section: Vapour Fixation Techniquesmentioning

confidence: 99%

Studies on the anhydrous fixation of dry seeds of lettuce (Lactuca saliva L.)

Smith

1991

New Phytologist

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“…It was shown that such formaldehyde-treated protein capsules substantially reduced BH of CLA in vitro [86]. The application of formaldehyde to emulsions in order to create cross-linking of protein is also non-targeted, meaning it is hard to prevent formaldehyde from reacting with other nutrients besides proteins such as, for example, unsaturated FA [87]. Although, formaldehyde treatment is considered to be the most effective technique so far, its application remains limited nowadays due to its high cost, the bad image of chemical treatments of feedstuffs and possible residues in the final animal products [8].…”

Section: Aldehyde Treatmentmentioning

confidence: 99%

State of the art in rumen lipid protection technologies and emerging interfacial protein cross‐linking methods

Gadeyne

Neve

Vlaeminck

et al. 2016

Euro J Lipid Sci & Tech

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Polyunsaturated fatty acids given to ruminants are to a large extent hydrogenated to more saturated forms by microbial metabolism. Numerous protection technologies have been developed to overcome this hydrogenation process in order to increase the amount of unsaturated fatty acids bypassing the rumen and resulting in an effective transfer to the peripheral tissues. This review gives an overview of the current state of the art in rumen lipid bypass technologies, with the focus on both patent-described protection mechanisms, possible advantages or drawbacks of the technologies, and protection results being described in recent scientific literature. Lipid bypass techniques which are dealt with include calcium salts, fatty acyl amides, aldehyde treatment, non-enzymatic browning, lipid composite gels, and encapsulation within lipids. Further, the potential of a novel rumen lipid protection technology, based on interfacial cross-linking of emulsions, is explored. Therefore, an overview is given on current knowledge of different types of enzymatically induced cross-linking of protein at emulsion interfaces, both for existing food and possible ruminal bypass applications. Practical applications: Both from a human and animal health care as well as from a resource-saving and economic perspective, protection of PUFA from ruminal BH is of interest. Protection, release, and absorption principle of a lipophilic rumen bypass product: As polyunsaturated fatty acids (P) are hydrogenated to more saturated fatty acids (S) upon ruminal passage (panel A), P sources administered to ruminants have to be protected against microbial turnover to transfer them to the peripheral tissues (panel B)

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“…Jones has found a reaction of formaldehyde with unsaturated fatty acids studying the fixation of fabrics [16,17]. Using stoichiometric amounts of alkyl aluminium chlorides Metzger could show that it is pos-sible to link formaldehyde to several unsaturated fatty acids and its derivatives [18].…”

Section: Introductionmentioning

confidence: 99%