Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “polyploidization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed1997

Vertebrate evolution by interspecific hybridisation--are we polyploid?

For the growing fraction of human genes with identified functions there are often homologues known from invertebrates such as Drosophila. A survey of well established gene families from aldolases to zinc finger transcription factors reveals that usually a single invertebrate gene corresponds to up to four equally related vertebrate genes on different chromosomes. This pattern was before widely noticed for the Hox gene clusters but appears to be more general. Genome quadruplication by two rounds of hybridisation is discussed as a simple biological mechanism that could have provided the necessary raw material for the success of vertebrate evolution.

Animals↗
PubMed1988

Endocrine profile of follicles containing oocytes with subsequent polyploid fertilization.

In an attempt to identify oocytes at risk for polypronuclear fertilization, follicular fluids were obtained retrospectively that contained oocytes that fertilized normally and abnormally. Whenever possible, each patient served as her own control during the same stimulation cycle. Twenty-six of 169 patients had oocytes that became polypronuclear, and of those 26, 21 had oocytes that fertilized and cleaved normally. Follicular fluids were analyzed for estradiol, progesterone, androstenedione, transferrin, and insulin. Insulin levels were noted to be significantly elevated (P less than 0.05) in the polypronuclear group when compropose that insulin, a known growth factor for granulosa cells cultured in vitro, when present in excessive concentrations may predispose to polypronuclear fertilization.

Estradiol↗
PubMed1998

Polyploidization and exit from cell cycle as mechanisms of cultured melanoma cell resistance to methotrexate.

Numerous malignant neoplasias are found to contain varying proportions of high-ploidy cells. Although the role they play in the tumor is poorly understood, several lines of evidence suggest that these cells could be especially resistant to various aggressions, a possibility of great interest in cancer treatment. In the present study, we tested this hypothesis through the analysis of the presence of high-ploidy cells following the administration of the chemotherapeutic agent methotrexate. We also determined the expression of two proliferation markers, PCNA and CDK1, after methotrexate-treatment. Cultured cells from the murine melanoma B16F10 were treated with high doses of methotrexate for seven days prior to determination of DNA content and proliferation markers. Our results showed an obvious increase in the mean ploidy of this population. Specifically, there was a dramatic reduction in the proportion of tetraploid cells (predominant in the original population), and an increase in the proportion of cells with higher ploidies, particularly those whose DNA content was greater than 8c, including some cells with ploidies greater than 16c. Furthermore, there was a reduction in the number of PCNA-expressing cells and the reduction was much more marked in the case of CDK1 that was almost absent in the modal-ploidy treated cells. These alterations concerning ploidy and expression of proliferation markers had completely reverted two weeks after withdrawal of the drug. Our results indicate that methotrexate at a high dosage selects a cell population heterogeneous concerning its ploidy level, composed of one subpopulation of high-ploidy cells and another of modal-ploidy cells that, considering its lack of CDK1 expression, would remain in a latent state to evade the effects of the drug.

Animals↗
PubMed2000

Characterisation of microsatellite markers from sugarcane (Saccharum sp.), a highly polyploid species.

Cultivated sugarcane varieties (Saccharum spp) are derived from complex interspecific hybridisations between the species S. spontaneum (2n=40-128) and S. officinarum (2n=60 or 80). To analyse this complex genome, the potential of microsatellite repeats as genetic markers in sugarcane with respect to their abundance, variability and ability to detect polymorphisms was investigated. A set of microsatellite markers for genome analysis in cultivated sugarcane was identified from an enriched genomic DNA library constructed from Saccharum sp. cv Q124. Sequencing of 798 sugarcane genomic DNA clones from an enriched microsatellite library, yielded 457 inserts containing microsatellite repeat motifs. Just over 84% of the microsatellites contained dinucleotide or trinucleotide repeats averaging 15 and 13 repeat motifs, respectively. Primer sets were designed and synthesised for over 100 microsatellite sequences and tested on a set of five sugarcane cultivars. Both, heterozygosity as witnessed by the number of alleles, and length polymorphisms as seen in the differences in PCR product size for a particular allele were observed. Microsatellite markers are likely to have many applications in sugarcane genetics and breeding including germplasm analysis, cultivar identification, parent evaluation and marker assisted breeding.

Journal Article↗
PubMed2003

Subgenome-specific markers in allopolyploid cotton Gossypium hirsutum: implications for evolutionary analysis of polyploids.

We developed a set of genetic markers specific to the A and D genome types of cotton using representational difference analysis (RDA). These markers produce amplification products with genomic DNA from allotetraploid cotton Gossypium hirsutum. One of the markers is a polymorphic amplified restriction fragment (PARF) - a sequence found in both A and D genomes but differently flanked by restriction sites. Results of phylogenetic analysis of the PARF sequences from diploid cottons and from allotetraploid G. hirsutum agree with a previous observation of the interlocus concerted evolution (sequences corresponding to A and D genomes are homogenized to a D genome-type sequence). Our study shows how RDA can be used to develop genome-specific markers that can be used to study molecular evolution of allopolyploids.

DNA, Plant↗
PubMed2000

Natural polyploidization of some cultured yeast Saccharomyces sensu stricto: auto- and allotetraploidy.

Using genetic and flow cytometric analyses, we showed that wine strain S6U is an allotetraploid of S. cerevisiae x S. bayanus. Hybrid constitution of the strain and its meiotic segregants was confirmed by Southern hybridization analysis of their chromosomal DNAs using four S. cerevisiae cloned genes: LYS2 (chr. II), TRK1 (chr. X), ARG4 (chr. VIII), ACT1 (chr. VI) and PCR/RFLP analysis of the MET2 gene (chr. XIV). Monosporic progeny of strain S6U was highly viable in first generation but completely nonviable in the second one. According to the genetic analysis, sherry strain S. cerevisiae SBY 2592 was found to be an autotetraploid heterozygous for homo-heterothallism.

Mycological Typing Techniques↗
PubMed2001

Polyploid evolution: keeping the peace at genomic reunions.

Incompatible gene or chromosomal combinations brought together in allopolyploid genomes cannot be purged through Mendelian segregation. But recent studies suggest that the elimination of DNA sequences and alteration of DNA methylation patterns may permit the restoration of fertility in some allopolyploids.

Animals↗
PubMed2003

Chronological and replicative lifespan of polyploid Saccharomyces cerevisiae (syn. S. pastorianus).

Chronological lifespan may be defined as the result of accumulation of irreversible damage to intracellular components during extended stationary phase, compromising cellular integrity and leading to death and autolysis. In contrast, replicative lifespan relates to the number of divisions an individual cell has undertaken before entering a non-replicative state termed senescence, leading to cell death and autolysis. Both forms of lifespan have been considered to represent models of ageing in higher eukaryotes, yet the relation between chronologically and replicatively aged populations has not been investigated. In this study both forms of lifespan have been investigated in Saccharomyces cerevisiae (Syn. S. pastorianus) to establish the relationship between chronological and replicative ageing.

Barbiturates↗
PubMed2000

Ty1-copia-retrotransposon behavior in a polyploid cotton.

Retrotransposons constitute a ubiquitous and dynamic component of plant genomes. Intragenomic and intergenomic comparisons of related genomes offer potential insights into retrotransposon behavior and genomic effects. Here, we have used fluorescent in-situ hybridization to determine the chromosomal distributions of a Ty1-copia-like retrotransposon in the cotton AD-genome tetraploid Gossypium hirsutum and closely related putative A- and D-genome diploid ancestors. Retrotransposon clone A108 hybridized to all G. hirsutum chromosomes, approximately equal in intensity in the A- and D-subgenomes. Similar results were obtained by hybridization of A108 to the A-genome diploid G. arboreum, whereas no signal was detected on chromosomes of the D-genome diploid G. raimondii. The significance and potential causes of these observations are discussed.

Gossypium↗