Haploidisation is the process of halving the chromosomal content of a cell, producing a

haploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Here ''sets of chromosomes'' refers to the num ...

cell. Within the normal reproductive cycle, haploidisation is one of the major functional consequences of

meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...

, the other being a process of

chromosomal crossover Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' sister chromatids, non-sister chromatids that results in recombinant chromosomes. It is one of the fina ...

that mingles the genetic content of the parental chromosomes. 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 Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or of ...

, the result is a haploid lineage of cells. For example, experimental haploidisation may be used to recover a strain of haploid ''

Dictyostelium ''Dictyostelium'' is a genus of single- and multi-celled eukaryotic, phagotrophic bacterivores. Though they are Protista and in no way fungal, they traditionally are known as "slime molds". They are present in most terrestrial ecosystems a ...

'' from a diploid strain. It sometimes occurs naturally in plants when meiotically reduced cells (usually egg cells) develop by

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

. Haploidisation was one of the procedures used by

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

ese researchers to produce Kaguya, a

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

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

References

Genetics

See also

References