Thursday, 16 August 2007

Cheng Hong: Cytogenetics Q&A

Q1) Why we do not want the cells to enter into mitotic phase?
Ans: We add the colcemid(mitotic inhibitor) to prevent the cells from entering M phase so that the 2 sister chromatids will not be pulled apart so that we are able to do karyotyping.

Q2) What action can be taken to save cell cultures that have been already contaminated? OR do you just use the spares?
Ans: We will use the back up tube to harvest the cells if the back up tube is also contaminated we will add antibiotics to treat the cultures.

Q3) Does any procedures required for any types of identification of those chromosome 1-22?

Ans: There is a book on the banding for each of the chromosome so we can look out for the typical banding type to identify the respective chromosomes.

Q4) May i know how you collect "villius"??
Ans: Collection of the villius is a minor operation to be done in a operating theater. It is done with the aid of ultra sound, the villius is attached to the placenta( picture it as a tree: the roots are the villius and the soil as the placenta, the villius holds tightly to the placenta and the villius is attached to the amniotic sac which holds the fetus)

Q5) What is colcemid?
Ans: it is a mitotic inhibitor

Q6) if we forgot to subculture the cells , what are some actions you guys take?or do you guys have like a timetable thingy to remind you ouh today must subculture this 'plate'
Ans: on each tray we will stick the day/at which stage of the culture it is at, and we have to check the time table to know what to do with the cultures(subculture/harvest/feed after tiff/hold/backup)

Q7) What are some examples of mitotic inhibitors and what's the purpose of using the different media?
Ans: by using 2 different types to brand media (both media have about the same composition) is a preventive measure, if one brand of the media is contaminated/ have batch variation there is still another culture which will not be affected.

Q8) Explaining how does the humidity and temperature, height dropped at, amount of water present on the slide and concentration of cells, affect the spreading of the chromosomes, length and colour?
Ans: This really depends on the technicians, they have their preferred method. But generally if the temp is high the evaporation rate is higher we will get darker, tighter chromosome as the chromosome do not have much time to spread(thus making analyzing difficult, also affects the staining). If the temp is colder and the humidity is high, the evaporation rate is slower thus the chromosome has a lot of time to spread causing pale and long chromosomes (to counter it we use a slightly drier slide to make or we do the slide making in the thermothron, where the humidity can be controlled)

Q9)For the blood harvesting, what is the purpose of the hypotonic solution?
Ans: the hypo solution is to swell up the nucleus of the cell so that the chromosomes have space to spread making analyzing easier is there is fewer overlaps.

Q10) Pictures that show normalites & abnormalities of karyotye?
Ans: i will try to get it and post asap

Q11) You said that you have to warm up beaker containing washed glass slides, to 90C. In our lab, we dun warm up the beaker containing the slides. The slides are washed and kept in DI water in the fridge. When we wanna dropslide we fill pour away the water and fill it up with new D.I water . Why issit that u have to warm it??
Ans: the warming of the slides really depends on the preference of the technologist as in the lab is quite cold so we warm the slides to aid in the evaporation of the film of water and the spreading of the chromosome.

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