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 ?
gigas cultivated in Ahome presented a decreased in survival for both ploidies from June to August, meanwhile survival of ND and NT oysters decreased from August to October.
The ANOVA test practiced to CI showed similarities (F = 0.91, P = 0.47) among the ploidies with peak values of 64.31, 63.96, 43.88, 49.40, 50.34, and 49.65 for ND, NT, GD, GT, AD, and AT groups, respectively (Fig.
The higher profits were registered for both ploidies from the Guasave farm (US$8,053.71 for GD and US$8,182.19 for GT).
When contrasting the mean numbers of males and females between ploidies, no significant differences were found for Bacorehuis, but significant differences were found at Rancho Bueno and Ceuta, where on the average, more males were present within triploids than diploids (Fig.
The observed growth (body weight) between culture sites for both ploidies followed a pattern of best growth occurring within the site with the highest ACH L-a: ATD ratio and the least growth occurred at the site with the lowest ACHL-a:ATD ratio.
In the present work, fecundity was used as a measure of reproductive output to compare both ploidies and culture sites.
Mortality was found to be similar between the 2 ploidies in S.
virginica exhibit a clear advantage over diploids even when both ploidies are disease resistant, as observed previously in S.
The results of Harding (2007) could be explained by the lack of measurements on smaller oysters combined with large differences in initial size between ploidies, taking into account that the most rapid growth is observed during the first 2 y of life (Kraeuter et al.