Avantages et inconvénients de l'acétate d'uranyle en virologie comparée: étude de quatre bactériophages caudés

Abstract

Effects of uranyl acetate (UA) and potassium phosphotungstate (KPT) on dimensions of four tailed bacteriophages have been studied comparatively. All UA stained preparations show positive (UA+) or negative (UA−) staining according to the local, low- or high-particle concentration, and crystals containing swollen, distorted phages. UA causes flattening or shrinking of phage heads, the latter especially after positive staining. Transverse diameters of elongated heads are reduced, and capsids, tails, and tail fibers may be swollen. In addition, isometric heads may show pentagonal outlines and tails may be elongated. Dimensions of phages TP50 and PBP1 have been analyzed by the method of multiple discriminant analysis. Differences between KPT, UA−, and UA+ stained viruses are statistically highly significant (P < 0.001). Dimensions of UA+ stained viruses appear to be unreliable for taxonomic purposes. Dimensions of UA− stained viruses are to be controlled by other staining methods. UA has several advantages but phosphotungstate stains should be preferred, particularly in staining large cubic DNA viruses.