Why do stem cells have large nuclei?

Answer 1

Having spent the last week looking at papers relating to neurons, nuclei and nucleoli while trying to answer a related question, I think it would be fair to say that, at the moment, nobody knows.

I have a hunch as to what the answer might be, but I can't find anyone else with the same idea, so it is perhaps a little too soon to post the idea here

Answer 2

Even though mitosis helps in the growth of an organism not only in the size but also in population, it is a highly related phenomenon. By mutational studies in yeast cells, as many as 38 or more steps have been identified to take part in mitosis, of which some are highly crucial in the progression of mitotic stages. If there are any mutations in the genome that control this process, cell division is completely inhibited or completely goes out of order or it may end up in an uncontrolled mitotic divisions. Under normal conditions, particularly in multicellular organisms, mitotically derived cells undergo differentiation and perform specific functions. Instead, in an uncontrolled process, cells undergo continuous multiplication by repeated mitosis. In these cases the cell derivatives do not undergo any differentiation, but they divide and redivide endlessly. As a consequence of this, innumerable cells of the same kind are formed. Such a group of cells which are endowed with a potentiality to divide and redivide ceaselessly is called tumor cells and the disease thus produced is referred to as cancer. This can be induced by various carcinogenic agents like drugs, X-ray irradiations and even some viruses. Certain spontaneous mutations may also cause growth.

The analysis of cancer cells indicates that the rapid and uncontrolled cellular divisions are due to some changes in the regulatory chromosomal proteins called non-histones. Identification of such causative non-histones is very essential and important to cure the cancer disease.

In plants, however, callusing or callus formation is another example of uncontrolled, undifferentiated tumor formation. Nevertheless the callus formation is known to be controlled by certain phytohormones like Auxins. The special feature of these hormones is that at particular concentration, they induce tumor formation in plant cells, but at a different concentration with other hormones like cytokinins, they may induce differentiation of shoots or roots. The probable mechanism by which the hormones cause callus formation is again attributed to differential gene expressions or due to certain modifications of nonhistones proteins, which actually trigger off the cellular components to undergo such uncontrolled cell divisions.