摘要:

SUMMARYTobacco mosaic virus (TMV), tobacco rattle virus (TRV),Tipulairidescent virus (TIV), turnip yellow mosaic virus (TYMV), T2phage and Lambda phage were examined by freeze‐etching water/glycerol suspensions. It was found that the virus particles usually fracture internally.TMV rarely fractures at its surface. Careful consideration of the fracture planes within TMV indicates not only that the TMV subunits do not fracture but also that there are no ‘preferred planes’ of fracture. An unexpected channel appears at the position of the RNA in TMV on one side of the capsid only. It is proposed that this indicates that the fracture of RNA is out of step with that of the subunit. By deep‐etching, a 5 nm repeat can sometimes be seen at the capsid surface of TMV (vulgare).TRV sometimes fractures to reveal its surface. It is proposed that this indicates that the surface of this rod‐shaped virus is smoother than that of the similar TMV.The large icosahedral virus, TIV, fractures between core and coat protein. The core which appears to consist of globular subunits is icosahedral and fits closely into its enclosing coat. The coat thickness is 10–12 nm. Numerous collapsible fibrous projections (probably up to 150 nm long) project from the surface of the coat.T2phage sometimes fractures to reveal the surface of the enclosed DNA which is smooth and very compact.Fracture by the freeze‐etch technique is shown to be a valuable adjunct to other techniques for the study of virus structure. It can reveal otherwise hidden internal structures. It may also disclose planes of minimum chemical bond energies represented by recurring regular fracture planes.The technique appears to be unsuitable, however, for the smaller viruses TYMV and

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01041.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYIn mouse and fish olfactory mucosæ, lanthanum has been found to penetrate various intracellular components of cells including the endoplasmic reticulum, mitochondria, microvilli, microtubules and cilia, outlining their substructure in negative contrast when seen in sectioned specimens.Structural details approaching those seen in disrupted negatively stained material were observed in sections, suggesting that intracellular lanthanum staining may prove a useful tool in morphological studies

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01042.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01043.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01044.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe average density of bright spots in the (200) region of field‐ion microscope images is found to be related to the nominal molybdenum composition in a series of iron‐molybdenum alloys containing 1/2 to 5 weight percent molybdenum. The bright spot density is found to be proportional to the square of the tip radius and is thus linearly related to the surface area. This indicates that a correlation between the observed bright spot density and a bulk property is permissable. The bright spot density is also found to increase approximately linearly with molybdenum content, at least up to 3% molybdenum. Observation of specimens with similar amounts of molybdenum in solid solution but different nitrogen contents shows that the observed correlation is independent of the nitrogen content. Similarly, it is shown that the correlation is also independent of carbon content. Thus, it is concluded that the bright spot density is directly related to the amount of molybdenum in solid solution and can be used as a measure of the local molybdenum concentration. The nature of the bright spot contrast is discussed and is shown to be consistent with a current theory of image format

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01045.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYA scanning electron microscopic investigation has been made of the radial fracture surfaces of both weak and strong egg shells. Generally in weak and thin egg shells the mammillae were of irregular shape, very porous, frequently not attached to the outer shell membrane fibres and were cleaved both radially and transversally during fracture.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01046.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYMammalian and avian cells have been examined in the scanning electron microscope either after prior radio‐frequency sputter ion etching with different ions (hydrogen, helium, argon, oxygen) or after argon ion bombardment in the SEM. Whilst the pattern of erosion is similar in the different specimens, the etching pattern varies with the different gases. It has not been possible to relate the etching patterns to characteristic subsurface structure

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01047.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYProtoplasts and L‐phase variants derived fromStreptococcus fæiumstrain F24 were studied by scanning electron microscopy. Effects on morphology due to several osmotic stabilizers, the duration and kind of fixation, the type of specimen mounting, and the method of drying were examined. Conditions for optimal results were found which will allow further biological study of the L‐phase. Whereas air‐drying of broth‐grown L‐phase variants was satisfactory, agar‐grown colonies required the critical

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01048.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYWe present evidence that ultrathin frozen sections cut on the ultracryotome only partially thaw during the cutting action. This conclusion is derived from calculations of the loss of mechanical energy as the specimen strikes the knife. The mechanical energy is assumed to be completely transformed into heat which warms the freshly cut section.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01049.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYWhen channel plate intensification methods are used in field‐ion microscopy, image gases other than hydrogen and helium give bright images easily photographed with colour film. Since different phases in the specimen image differently with differing gases, colour photography through filters yields micrographs which accentuate these phase difference

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1972.tb01050.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY