haploidisation

{{Short description|Process of halving chromosomal content of a cell, producing a haploid cell}}

Haploidisation is the process of halving the chromosomal content of a cell, producing a haploid cell. Within the normal reproductive cycle, haploidisation is one of the major functional consequences of meiosis, the other being a process of chromosomal crossover that mingles the genetic content of the parental chromosomes.{{cite journal|url=http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2002;volume=48;issue=3;spage=232;epage=7;aulast=Kothari|title=Bipolar hermaphroditism of somatic cell as the basis of its being and becoming: celldom appreciated.|author=ML Kothari, L Mehta|year=2002|journal=Journal of Postgraduate Medicine|volume=48|issue=3}} Usually, haploidisation creates a monoploid cell from a diploid progenitor, or it can involve halving of a polyploid cell, for example to make a diploid potato plant from a tetraploid lineage of potato plants.

If haploidisation is not followed by fertilisation, the result is a haploid lineage of cells. For example, experimental haploidisation may be used to recover a strain of haploid Dictyostelium from a diploid strain.{{cite journal | pmid = 7227041 | volume=82 | title=Genetic and cytological characterisation of fusion chromosomes of Dictyostelium discoideum | year=1981 | journal=Chromosoma | pages=321–32 | last1 = Welker | first1 = DL | last2 = Williams | first2 = KL | doi=10.1007/bf00285758}} It sometimes occurs naturally in plants when meiotically reduced cells (usually egg cells) develop by parthenogenesis.

Haploidisation was one of the procedures used by Japanese researchers to produce Kaguya, a mouse which had same-sex parents; two haploids were then combined to make the diploid mouse.

Haploidisation commitment is a checkpoint in meiosis which follows the successful completion of premeiotic DNA replication and recombination commitment.{{cite journal | pmc = 218468 | pmid=762020 | volume=137 | title=Uncontrolled septation in a cell division cycle mutant of the fission yeast Schizosaccharomyces pombe | journal=J Bacteriol | pages=440–6 | last1 = Minet | first1 = M | last2 = Nurse | first2 = P | last3 = Thuriaux | first3 = P | last4 = Mitchison | first4 = JM}}