Sunday, 9 May 2010

GGS LIVE - broken chromosomes

Welcome you all,

today in Biochemistry Methods section we discuss how to assess chromosomal stability. Chromosome aberration is one of the methods.

Method: Chromosome Aberrations.

About: Chromosome aberration assay is a direct method to assess chromosomal abnormalities.

How: By visual examination of chromosomes.

To examine chromosomal stability of chicken DT40 cell line we first need to prepare chromosomal spreads (please have a quick look at this post Meet the chickens - chook chromosomes at hand). To prepare such chromosome spreads, we have to capture them in metaphase (subphase of cell division - mitosis). Usually drug called colcemid is used for that (look at the picture below).

Colcemid is a drug that interfere with formation of mitotic spindle by depolymerization of microtubules. This way we enrich population of cells that already condensed their DNA, which now has a form of chromosomes.
Later cells are harvested and incubated in hypothonic buffer (what cause their swelling) to make them more fragile. Next step is to fix them in such state and drop them onto slide. Cells burst/break when they are dropped, releasing chromosomes (as on the picture below or in this post Meet the chickens - chook chromosomes at hand).

Picture taken by Kliszczak M.

As you can see, breaks in chromosomes can be easily seen and scored (red arrow heads). Usually cells are left untraeted (to score spontaneous aberrations) and treated with ionizing radiation (IR) or with drug of interest. Chromosomal aberrations are then scored and compared to untreated sample.

I hope you enjoy it.


1 comment:

  1. hello.where are pursuing ur ph.d in biochem.m interested too.can u pl enlighten wit some knowledge about career path. regards,vasavi rao