Iso-labelling in BrdU-substituted chromosomes

The Origin of Iso-Chromosomes at Meiosis.

N 1.50-CHROMOSOME is a chromosome having two identical arms A (DARLINGTON 1939). Such chromosomes have been studied recently by RHOADES (1940) in Zea and by DARLINGTON (1940) in Fritillaria. It is also very probable that the extra chromosomes in secondary trisomics, such as the numerous types which have been found in Datura (BLAKESLEE and AVERY 1938) are true iso-chromosomes. The manner in whic...

New staining method for the detection of sister-chromatid exchanges in BrdU-labelled chromosomes.

A direct Giemsa technique is described for the selective staining of Brd-U-substituted chromatin. It can advantageously be used for sister-chromatid exchange analysis and for the detailed cytological study of the mouse kinetochores. Presumptive inversions within the centromeric region of chromosomes 4 and 18 in the C57Black/6J mouse are described.

Interaction of chromosomal proteins with BrdU substituted DNA as determined by chromatin-DNA competition.

Chromatin-DNA competition has been utilized to examine the general nature of chromosomal proteins interacting more strongly with BrdU substituted DNA. When chromatin is incubated with an excess of purified DNA, a portion of the chromosomal proteins will exchange to the purified DNA. These two complexes can then be separated on Metrizamide gradients due to their differing protein/DNA ratios. Usi...

A Pericentric Inversion in Gasteria Resulting in Apparent Iso-Chromosomes at Meiosis.

The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes.

AA8 Chinese hamster ovary cells were treated with halogenated nucleosides analogues of thymidine, namely CldU, 5-iodo-2'-deoxyuridine (IdU), and 5-bromo-2'-deoxyuridine (BrdU), following different experimental protocols. The purpose was to see whether incorporation of exogenous pyrimidine analogues into DNA could interfere with normal chromosome segregation. The endpoint chosen was endoreduplic...