Locust haemolymph lipoproteins visualised in the electron microscope
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In matureLocusta, the haemolymph lipoproteins change both in quality and quantity according to the physiological state of the animal. In resting locusts the majority of lipid in the haemolymph is carried by lipoprotein Ayellow, but during flight or after adipokinetic hormone injection, Ayellow joins together with extra diacylglycerols from the fat body and non-lipid carrying CL-proteins to form another lipoprotein, A+. In this study partially purified Ayellow and A+ lipoproteins have been visualised by transmission electron microscopy after negative staining or shadowing. Both Ayellow and A+ lipoproteins are discrete particulate structures but they differ markedly in size; Ayellow particles are 9–16 nm in diameter while those of A+ are mostly in the range 20–50 nm. Large lipoprotein particles of the A+ type have not been described previously in insect haemolymph but, interestingly, the locust A+ particles do resemble most closely the low density lipoprotein particles described in human serum by Forte and Nichols (1972).
KeywordsAmmonium Sulphate Negative Staining Flight Muscle Lipid Loading Ammonium Sulphate Solution
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