"Internal Memo: The Structure of the Solenoid"

Date:: [c. 1976]

Reference:: PP/CRI/H/6/5

Catalogue details

Licence: In copyright

Credit: "Internal Memo: The Structure of the Solenoid". Source: Wellcome Collection.

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There are plausible arguments for both alternatives. If the linker lies outside, its easy accessibility to enzymes would follow naturally. However it is not clear that all solenoids in the nucleus are perfect. Possibly small nucleuses could get up the centre of the solenoid. Perhaps solenoids are mainly attacked by micrococcal nuclease from their ends. Similar arguments, for and against, apply to the easy digestion of Hi by proteolytic enzymes. The alternative, that its linker is towards the centre of the solenoid, has the disadvantage that there is only a limited space there for the extra DNA which has to be pakjced when the linker is long. However it would explain very nicely the dis tribution of stain found by Howard Davis for the nucleus of the chick erythrocyte, though unfortunately this argument is only suggestive. Its major appeal is that it could make an intact solenoid a very inert structure. To decide between these two alternatives looks difficult. However if the latter idea is correct then it is just possible that the nuclei of rabbit neuronal cells, with a repeat about 175 bp might show a hole Cwhen stained for DNA) in the e/m whereon rabbit glial nuclei, with a repeat of about 200 bp, might have this hole filled with the entire DNA. The two models lead to rather different configurations for the DNA in the 140 bp particle. Briefly, for the first alternative the DNA turns are nearer together but the ends

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