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Studies in chromosome structure and replication.


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Geard, Charles Ray 1969 , 'Studies in chromosome structure and replication.', Unspecified thesis, University of Tasmania.

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A quantitative analysis of sister chromatid
exchanges and labelling patterns in H 3 thymidine labelled
second division (post isotope incorporation) chromosomes
of Vicia faba has demonstrated that:
(1) The frequency of sister chromatid exchanges per
chromosome is proportional to chromosome length.
(2) The time of availability of colchicine may have a
slight effect on the prospects of sister chromatid
exchange events. However, overall, colchicine has
no significant effect on the frequency of sister
chromatid exchanges; on the incidence of isolabelling
or on the type of iso-labelling
(3) The distribution of sister chromatid exchanges per
chromosome follows a Poissonian form. The prospects
of sister chromatid exchange events at either the
first or second interphases are equal and
(4) The ratio of single to twin sister chromatid
exchange is consistent with the expectation that;
sister chromatid exchanges occur independently of
the tritium dose, and that chromosomal sub-units
rejoin non-randomly, i.e. they exhibit polarity and
are dissimilar in an analagous manner to the DNA
double helix.
(5) A high frequency of chromosomes show isolabelling,
the probability of which increases with chromosome
length and/or exchange frequency.
(6) Twin and single isolabelling segments have been
noted, however the ratios obtained do not fit those
for sister chromatid exchanges and the origin of
isolabelling remains unexplained.
Mitotic cycle determinations using the labelled
mitosis wave method and the double labelling method have
been carried out for Vicia faba and Spironema fragrans
root tips. The variability of such methods has been
commented on.

Item Type: Thesis - Unspecified
Authors/Creators:Geard, Charles Ray
Keywords: Chromosomes
Copyright Holders: The Author
Copyright Information:

Copyright 1969 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (M.Sc.) - University of Tasmania, 1969. Bibliography: l. 95-97

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