Ploidy

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Related to Ploidies: euploid, hypoploidy, alloploid, tetraploids

ploidy

[′plȯid·ē]
(genetics)
Number of complete chromosome sets in a nucleus: haploid (N), diploid (2N), triploid (3N), tetraploid (4N), and so on.

Ploidy

 

the number that indicates how many times the set of chromosomes characteristic of the germ cells of a given species is replicated in the cell nucleus. The majority of organisms that reproduce sexually are diploid, that is, each of their somatic cells contains two sets of chromosomes (one for each of the haploid germ cells or gametes). In nature and under artificial conditions, ploidy may change in multiples higher that two (eupioidy); there may also be a loss or gain of individual chromosomes (aneu-ploidy).

Euploid increase of the number of chromosome sets (poly-ploidization) occurs if the chromosomes do not separate during cell division. It may also result from the merging of nuclei containing more than one set of chromosomes. There are two types of polyploidy: autopolyploidy, in which the number of homologous sets of chromosomes is increased, and allopolyploidy, which arises when there is a joining, as a result of hybridization, of the genomes of various species. Nonseparation of genomes can occur only in part of the cells of some tissues (somatic polyploidy, which is characteristic of many multicellular animals and plants). Polyploidization can lead to the formation of new plant species and thus serves as an important factor in their evolution (as well as of unicellular organisms). Its significance for species formation in multicellular animals is apparently limited to par-thenogenetic forms. Aneuploidy leads to serious disruptions of development, which often lead to death of the organism and, therefore, does not play a significant role in evolution. Aneuploid cells are common in malignant tumors.

Methods have been elaborated for artificially altering ploidy. They are used to obtain economically valuable forms of plants and for research purposes (for example, to study the action of genes).

References in periodicals archive ?
The economic assessment was extrapolated to such amount of oysters pretending to provide an economic framework for comparison of the oyster ploidies in the cultivation sites only.
Mortality differed significantly among ploidies and sites (F = 21.
The USDA collection contains accessions of both ploidies from Switzerland.
caerulea; further research should be conducted to clarify the ploidies and species and subspecies assignments of other accessions in the M.
This permitted to analyze statistical differences between sites and ploidies.
Quantitative Analyses of Proportion of Males versus Females A reduced logistic model comparing only proportions of males and females (by modeling males) during the culture months for both ploidies and at each site indicated significant effects of ploidy (P = 0.
Significant differences in percentage to market size were detected between ploidies in both years (Table 3).
The mean yield (total weight of all live oysters) in 2006 and 2007 within and among sites and ploidies is presented in Table 6.
Levels of euploid (chromosome number) and aneuploid (chromosome number) produced in gynogenetic haploid group (G-n), gynogenetic diploid group (G-2n), normal diploid group (N-2n) and normal triploid group (N-3n) Percentage of Ploidies Observed Aneuploid Haploid Aneuploid Diploid Aneuploid Groups (<16) (16) (17-31) (32) (33-47) G-N 18.