While researching the F12 cell culture medium (Ham, 1965), I came across the term "essentially diploid Chinese hamster ovary cells". The terms "subdiploid" and "near diploid" were also used to refer to the same cells.

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Attempts at searching Google Scholar and regular Google failed to turn up a definition of the phrase.

What exactly is meant by "essentially diploid", and how is it different from regular diploid cells?

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    $\begingroup$ Secondary cell lines often show aneuploidy. I think it is a reference to that. $\endgroup$ – WYSIWYG Jul 22 '15 at 4:55

I think that the rest of the paragraph that you left out of your quotation helps to clarify. The CHO have 21 chromosomes, while the somatic lung cells have 23.

Neither case is exact for Chinese Hamsters, 2n = 22. So they have almost the complement of chromosomes that a diploid Chinese hamster somatic cell would have but they are missing one or have one extra. For the most part they will behave like normal somatic cells in culture, but it is an important fact to note as you can have cases where dosage dependence of a missing chromosome in a pair or an additional chromosome (trisomy) can affect the outcomes of research.

In the back of your mind you always need to be thinking how does the missing/extra chromosome affect the data I am collecting.

This Nature article may also be of interest.

  • $\begingroup$ @MarchHo, if you are not a native English speaker, then one thing that you need to remember about the English language is that it is contextual, and definition can often be defined from the context of usage. Here "essentially diploid," combined with the knowledge that 2n=22 and that the cell lineages are 21 and 23 chromosomes, means that while they are almost the same as somatic cells, they are not exact, which as I stated above has implications. If the CHO cells are missing an X-chromosome, then maybe it doesn't matter, as we now know about X-chromosome inactivations... $\endgroup$ – AMR Aug 21 '15 at 18:56
  • $\begingroup$ ... while a different chromosome might be problematic. They are "essentially diploid" but one should keep in the back of their mind that there could be effects to the missing/extra chromosome in these lines that could have implications to the research results and the conclusions drawn from the data. $\endgroup$ – AMR Aug 21 '15 at 18:58

"Essentially diploid" means that a normal (most common normal) state is diploid, while any other state will be considered rare (can be normal yet) or abnormal or unusual.

The "essentially diploid" is in some way a tautologic, since we can say "human somatic cell is essentially diploid" as well as "human somatic cell is diploid" omitting "essentially". But the goal of "essentially" is to clarify other states:

If some essentially diploic organism has one chromosome set it will be called "monoploid", while cell/organism etc which normally has one set will be called "haploid".

Sub-Diploid and Near diploid means there are incomplete (aka less than normal) sets of genetic material.

  • $\begingroup$ Do you have any references for your answer? $\endgroup$ – March Ho Jul 22 '15 at 22:31
  • $\begingroup$ @MarchHo Please, look at this one - ncbi.nlm.nih.gov/books/NBK21229 You can easuly find additional supporting refs if you need them. $\endgroup$ – Ilan Jul 22 '15 at 23:14

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