Ploidy

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ploidy

[′plȯid·ē]
(genetics)
Number of complete chromosome sets in a nucleus: haploid (N), diploid (2N), triploid (3N), tetraploid (4N), and so on.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Selection of haploidentical donor among the potential candidates sharing one haplo type with the patient.
Haplo HCT could be a good alternative in transplantation, as several case reviews have shown encouraging outcomes and improved survival rates amongst the patients.
Given the critical role of alloreactive NK cells in the GvL effect for patients undergoing T cell-depleted haplo HSCT, quantification and phenotypic analysis of NK cells in potential donors would enhance donor selection.
Assignment of a subset of these markers to this chromosome was confirmed by means of progeny derived by pollinating a plant monosomic for the N-carrying chromosome of Holmes Samsoun (derived by crossing Red Russian Haplo H with Holmes Samsoun) with pollen from TM[V.sup.S] cultivar K326.
But then a doctor at Birmingham Children's Hospital suggested manipulating her father Simon's bone marrow using what is known as the HAPLO technique.
(6) Pimenta et al, reported association of a new tumor suppressor gene (HRPT2) mutation with ossifying fibroma and proposed that these tumors could develop as a result of haplo in sufficiency of the particular gene.
The different SNPs were combined to generate the following mutant Pfdhfr/Pfdhps haplotypes: quadruple haplo type (double Pfdhfr [CICNI/CNRNI] with double Pfdhps [AGEAA/SGEAA]); quintuple haplotypes (triple Pfdhfr with double Pfdhps [CNRNI-AGEAA/SGEAA] or double Pfdhfr with triple Pfdhps [CICNI-SGEGA]); and sextuple haplotype (triple Pfdhfr [CIRNI] and triple Pfdhps [SGEGA]).
Her only hope is the specialist Haplo stem cell treatment at the ld d Child ' world-renowned Children's Hospital near Stuttgart, Germany.
A pairwise allelic linkage disequilibrium (LD) test for each adjacent pair of SNPs within each gene was performed, and for those SNPs in significant LD with each other (using the normalized D' measure), haplotypes were constructed using the R haplo.stats software ( http://cran.r-project.org/web/packages/haplo.stats/.
haplo. stats: Statistical Analysis of Haplotypes with Traits and Covariates When Linkage Phase Is Ambiguous.
According to the result of haplotype analysis, the haplotypes Haplo 1, Haplo 3, Haplo 7 and Haplo 9 were the four main haplotypes, accounting for almost 90% of haplotypes found in the studied sheep populations, and Haplo 1 (CGAG) accounted for more than 30% (Table 3).