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Results for “polyploidy”

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At least 289 records · Page 16Linked to original sources
PubMed1989

Myocardial (iso)enzyme activities, DNA concentration and nuclear polyploidy in hearts of patients operated upon for congenital heart disease, and in normal and hypertrophic adult human hearts at autopsy.

To investigate biochemical characteristics of hypertrophic myocardium of young and adult humans, we analysed myocardial biopsies obtained from 28 mainly young patients undergoing cardiac surgery for congenital heart disease and 41 autopsied hearts from 18 adult normal and 23 hypertrophic human subjects. Myocardial activities of the enzymes creatine kinase and lactate dehydrogenase were independent of age during childhood, but decreased significantly with hypertrophy at adult age. Myocyte nuclei showed increased polyploidization during childhood which was progressive with age, and in the adult stage polyploidization was correlated with heart weight. Nevertheless myocardial DNA concentration fell under both conditions, which is to be ascribed to the 'diluting' effect of myocyte hypertrophy. Before an age of 8 years DNA concentration in the child heart material studied has reached the value found in adult nonhypertrophic hearts, although at that time polyploidization of myocyte nuclei in child hearts was only half the value found in adult non-hypertrophic hearts. Biochemical measurement of DNA concentration in peroperatively taken myocardial biopsies may contribute to the in vivo diagnosis of ventricular hypertrophy in quantitative terms, in combination with radiology, echocardiography and histology.

Adolescent↗
PubMed2005

Genetic and epigenetic consequences of recent hybridization and polyploidy in Spartina (Poaceae).

To study the consequences of hybridization and genome duplication on polyploid genome evolution and adaptation, we used independently formed hybrids (Spartina x townsendii and Spartina x neyrautii) that originated from natural crosses between Spartina alterniflora, an American introduced species, and the European native Spartina maritima. The hybrid from England, S. x townsendii, gave rise to the invasive allopolyploid, salt-marsh species, Spartina anglica. Recent studies indicated that allopolyploid speciation may be associated with rapid genetic and epigenetic changes. To assess this in Spartina, we performed AFLP (amplified fragment length polymorphism) and MSAP (methylation sensitive amplification polymorphism) on young hybrids and the allopolyploid. By comparing the subgenomes in the hybrids and the allopolyploid to the parental species, we inferred structural changes that arose repeatedly in the two independently formed hybrids. Surprisingly, 30% of the parental methylation patterns are altered in the hybrids and the allopolyploid. This high level of epigenetic regulation might explain the morphological plasticity of Spartina anglica and its larger ecological amplitude. Hybridization rather than genome doubling seems to have triggered most of the methylation changes observed in Spartina anglica.

DNA Methylation↗
PubMed2025

Polyploidy-mediated variations in glutamate receptor proteins linked to Fusarium wilt resistance in upland cotton.

Cotton production in the US faces a serious threat from Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4), a soil-borne fungus causing Fusarium wilt by infecting the roots and vascular system of susceptible cotton, leading to rapid wilting and death. Here, we investigate genetic mechanisms of resistance to FOV4 in the highly resistant upland cotton genotype "U1" using an early-generation segregating biparental population ("U1" × "CSX8308") with comprehensive genomic resources. Reference-grade genomic assemblies of the parents revealed minor structural variations between "U1" haplotypes, a high degree of collinearity at chromosome synteny and micro-synteny levels, and significant divergence from "CSX8308" with 8.9 million SNPs. QTL analysis identified significant markers on chromosomes D03 and A02 linked to reduced Fusarium wilt severity. Within these regions, two glutamate-receptor-like (GLR) genes showed structural variation and overlapped between translocated segments on A02 and D03, suggesting a rare but important reinforcing effect of parallel evolution between susceptible and resistant genotypes. Transcriptome profiles of "U1" under FOV4 infection reveal activation of calcium-binding proteins and transcription factors regulating plant hormones (ethylene, abscisic acid, jasmonic acid, and salicylic acid), along with enzymes involved in cell wall remodeling and phytoalexin production. Advancing cotton improvement depends on incorporating durable genetic disease resistance into high-yielding, high-quality cultivars.

Fusarium↗
PubMed1970

Polyploidy in the common tree toad Hyla versicolor Le Conte.

A karyotype of the first known naturally occurring anuran polyploid in North America is described. Hyla versicolor, the common tree toad, is tetraploid (2n-->4n=48). Individual chromosmes representing, each set of four of the Hyla versicolor karyotype correspond closely with those of the diploid (2n = 24) Hyla andersonii karyotype.

Animals↗
PubMed1994

Correlation between polyploidy and auxotrophic segregation in the imperfect yeast Candida albicans.

In order to clarify the relationship between polyploidization and the capability of phenotypic switching in the imperfect yeast Candida albicans, two types of variants were isolated as segregants from a fusant, which produced a proportion of the cell population with a higher ploidy than the rest, either in a temperature-dependent or -independent manner, when incubated at low (28 degrees C) and high (37 degrees C) temperatures. In the case of the temperature-dependent type of variants, high-ploidy cells appeared at 37 degrees C but rarely at 28 degrees C. This phenotype was named Pldts (temperature-sensitive polyploidization), and the temperature-independent phenotype was called Pld-. The appearance of high-ploidy cells in the culture of the Pldts strain at 37 degrees C was accompanied by a significant increase in the frequency of auxotrophic variants; these variants probably occur as a result of segregation of auxotrophic markers from the heterozygous to the homozygous state. Both Pldts and Pld- phenotypes were recessive in a fusion with a Pld+ parent. An adenine auxotrophic marker (ade1) was introduced into a Pldts strain in a heterozygous state, and the individual high-ploidy cells of this strain, grown at 37 degrees C, were micromanipulated to form colonies, which consisted of red and white sectors appearing at high frequency on a pink background. When the ade1 auxotrophy was introduced into Pld- strains, frequently sectored colonies were produced. These results suggested an increased level of chromosome missegregation in both types of Pld mutants. Analyses by pulsed-field gel electrophoresis of Ade-segregants, derived from a micromanipulated high-ploidy cell of a Pld(ts) strain, suggested the occurrence of nonreciprocal recombination, some of which includes chromosome loss.

Adenine↗
PubMed1975

[Karyotypes, supernumerary chromosomes, rudimentary parthenogenesis and polyploidy in 2 species of the genus Phronima (Crustacea, Amphipoda)].

The diploid number of Phronima sedentaria and P. atlantica is 30, all the chromosomes are metacentric or submetacentric; the caryotypes of these two species are compared with those of other Amphipods. Some individuals of each species have a supernumerary chromosome. This element, found in both sexes, remains as an univalent at meiosis and goes earlier to one pole. In some cases nonfertilized ova undergo segmentation; this rudimentary parthenogenesis stops quickly and is partly related to polyploidization.

Aneuploidy↗
PubMed1999

Partial hepatectomy-induced polyploidy attenuates hepatocyte replication and activates cell aging events.

In understanding mechanisms of liver repopulation with transplanted hepatocytes, we studied the consequences of hepatic polyploidization in the two-thirds partial hepatectomy model of liver regeneration. Liver repopulation studies using genetically marked rodent hepatocytes showed that the number of previously transplanted hepatocytes did not increase in the liver with subsequential partial hepatectomy. In contrast, recipients undergoing partial hepatectomy before cells were transplanted showed proliferation in transplanted hepatocytes, with kinetics of DNA synthesis differing in transplanted and host hepatocytes. Also, partial hepatectomy caused multiple changes in the rat liver, including accumulation of polyploid hepatocytes along with prolonged depletion of diploid hepatocytes, as well as increased senescence-associated beta-galactosidase and p21 expression. Remnant hepatocytes in the partially hepatectomized liver showed increased autofluorescence and cytoplasmic complexity on flow cytometry, which are associated with lipofuscin accumulation during cell aging, and underwent apoptosis more frequently. Moreover, hepatocytes from the partially hepatectomized liver showed attenuated proliferative capacity in cell culture. These findings were compatible with decreased proliferative potential of hepatocytes experiencing partial hepatectomy compared with hepatocytes from the unperturbed liver. Attenuation of proliferative capacity and other changes in hepatocytes experiencing partial hepatectomy offer novel perspectives concerning liver regeneration in the context of cell ploidy.

Animals↗
PubMed1998

Vascular smooth muscle cell polyploidy and cardiomyocyte hypertrophy due to chronic NOS inhibition in vivo.

To assess the vascular and cardiac response to NO (nitric oxide) synthase (NOS) blockade in vivo, Wistar-Kyoto rats (WKY) were treated for 3 wk with NG-nitro-L-arginine methyl ester (L-NAME; 10 mg.kg-1.day-1). L-NAME treatment induced hypertension that was associated with increased plasma renin activity. Flow cytometry cell cycle DNA analysis showed that aortic vascular smooth muscle cells (VSMC) from L-NAME-treated WKY had a significantly higher polyploid population compared with WKY controls. Using organ bath experiments, we have shown that aortic rings from L-NAME-treated WKY have an increased contractile response to phenylephrine and impaired relaxation to carbachol compared with control rings. NOS blockade in vivo caused a significant increase in cardiac and left ventricular hypertrophy. Northern mRNA analysis of the myocardium showed that L-NAME treatment caused reexpression of the fetal skeletal alpha-actin isoform without alterations in collagen type I expression, a pattern indicating true hypertrophy of the cardiomyocytes. These studies provide further insight to confirm that NO deficiency in vivo results in the development of vascular and cardiac hypertrophy.

Actins↗
PubMed2005

Biogeographic distribution of polyploidy and B chromosomes in the apomictic Boechera holboellii complex.

The Boechera holboellii complex comprises B. holboellii and B. drummondii, both of which can reproduce through sex or apomixis. Sexuality is associated with diploid individuals, whereas apomictic individuals are diploid or triploid and may additionally have B chromosomes. Using flow cytometry and karyotype analysis, we have shown that B chromosomes (a) occur in both diploid and triploid apomictic B. holboellii, (b) may occur in triploid B. drummondii, and (c) are dispensable for the plant. Both diploid and triploid karyotypes are found in multiple chloroplast haplotypes of both species, suggesting that triploid forms have originated multiple times during the evolution of this complex. B chromosome carriers are found in geographically and genetically distinct populations, but it is unknown whether the extra chromosomes are shared by common descent (single origin) or have originated via introgressive hybridization and repeated transitions from diploidy to triploidy. Diploid plants containing the Bs reproduce apomictically, suggesting that the supernumerary elements are associated with apomixis. Finally, our analyses of pollen size and viability suggest that irregular chromosome segregation in some triploid lineages may lead to the generation of diploid individuals which carry the B chromosomes.

Brassicaceae↗