Login or Subscribe Newsletter. Haploid cells, which contain one copy of each chromosome, should not undergo further reduction of their chromosome number through a type of cell division called meiosis. To prevent such a catastrophic event, haploids block the production of a protein called IME4, which triggers meiosis, by expressing antisense IME4.
Failure to block sense IME4 results in the aberrant meiotic events shown above in pink. David Cameron, Whitehead Institute November 21, Researchers have found that a class of RNA molecules previously thought to have no function may in fact protect sex cells from self-destructing.
When a gene is ready to produce a protein, the two strands of DNA that comprise the gene unravel. The first strand produces a molecule called messenger RNA, which acts as the protein's template.
Biologists call this first strand of DNA the "sense" or "coding" transcript. Even though the other strand doesn't contain a protein recipe, it may also, on occasion, produce an "antisense" RNA molecule, one whose sequence is complementary to that of the messenger, or sense, RNA.
Antisense RNA has been detected for a number of genes, but is largely considered a genetic oddity. In other words, the gene disables its own ability to make protein. When conditions around yeast cells are good and rich in nutrients, the cells divide by mitosis--that is, the DNA duplicates so each daughter cell receives exactly the same number of chromosomes as the original cell. However, when the yeast cells are starving, IME4 switches on and activates a process called meiosis.
