SEARCH · PubMed Health

Results for “polyploidization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 1,693 records · Page 94Linked to original sources

PubMed2006

Cytogenetic characterization of Lippia alba and Lantana camara (Verbenaceae) from Brazil.

The aim of this work was to determine the cytogenetic characteristics of Brazilian Lippia alba (Mill) N. E. Brown and Lantana camara Plum. that could be useful for future characterization of these genera. Our analyses revealed that Li. alba has 2n=30 chromosomes consisting of ten metacentric and five submetacentric pairs, while La. camara has 44 metacentric chromosomes. The large blocks of heterochromatin seen in both species suggest an apomorphic condition. Six 45S rDNA sites were detected in both species by fluorescence in situ hybridization (FISH). Two and four 5S rDNA sites were observed in Li. alba and La. camara, respectively. Meiotic analysis revealed a normal chromosomal behaviour. The number of chromosomes and the presence of 45S rDNA and 5S rDNA sites do not exclude a possible polyploid origin. The cytogenetic differences between La. camara and Li. alba may be useful markers for differentiating these species.

Brazil↗

PubMed2006

Chromosome evolution in the Laurales based on analyses of original and published data.

We present a summary of currently available chromosome information for all seven families in the order Laurales on the basis of original and previously published data and discuss the evolution of chromosomes in this order. Based on a total of 53 genera for which chromosome data were available, basic chromosome numbers appear consistent within families: x = 11 (Calycanthaceae); x = 22 (Atherospermataceae and Siparunaceae); x = 19 (Monimiaceae); and x = 12 and 15 (Lauraceae). The Hernandiaceae have diverse numbers: x = 15 (Gyrocarpoideae) and x = 18 and 20 (Hernandioideae). Karyotype analyses showed that Hennecartia, Kibaropsis, and Matthaea (all Monimiaceae) contained two or three sets of four distinct chromosomes in 38 somatic chromosomes, suggesting that 2n = 38 was derived by aneuploid reduction from 2n = 40, a tetraploid of x = 10. In light of the overall framework of phylogenetic relationships in the Laurales, we show that x = 11 is an archaic base number in the order and is retained in the Calycanthaceae, which are sister to the remainder of the order. Polyploidization appears to have occurred from x = 11 to x = 22 in a common clade of the Siparunaceae, Atherospermataceae, and Gomortegaceae (although 2n = 42 in the Gomortegaceae), and aneuploid reduction from x = 11 to x = 10 occurred in a common clade of the Hernandiaceae, Lauraceae, and Monimiaceae. To understand chromosome evolution in the Lauraceae, however, more studies are needed of genera and species of Cryptocaryeae.

Aneuploidy↗

PubMed2004

Polymorphism of major ribosomal gene chromosomal sites (NOR-phenotypes) in the hybridogenetic fish Squalius alburnoides complex (Cyprinidae) assessed through crossing experiments.

Chromosomal locations of major ribosomal sites, i.e. NOR-phenotypes, were assigned in Squalius alburnoides complex using sequential chromomycin A3 (CMA3)- and silver (Ag)-staining. This hybridogenetic Iberian minnow comprises diploid, triploid and tetraploid forms that arose by interspecific hybridisation between S. pyrenaicus and an unknown species. Inheritance of NOR patterns was studied by means of crossing experiments involving most diploid-polyploid forms of the S. alburnoides complex with identified specific genotype constitution. In all the specimens studied, the NORs were localised in the short arms of submetacentric chromosomes. Although S. pyrenaicus presented only one pair of NOR-bearing chromosomes, the data from experimental crosses evidenced that S. alburnoides complex was characterised by a multiple NOR phenotype composed of one chromosome pair with stable NORs and two chromosome pairs with NOR site polymorphism of presence/absence type. These data suggest that the karyotype of the unknown parental species of the S. alburnoides complex should have a multiple NOR pattern and emphasised the role of the all-male diploid linage in the dynamics and evolutionary potential of the S. alburnoides complex allowing the preservation of the missing ancestor genome. Cross-analyses evidenced that in spite of the high polymorphic nature of NORs in this fish complex, we have no reason to reject the hypothesis that their inheritance patterns were in accordance with Mendelian segregation.

Animals↗

PubMed2006

Molecular characterization of three non-functional S-haplotypes in sour cherry (Prunus cerasus).

Tetraploid sour cherry (Prunus cerasus) exhibits a genotype-dependent loss of gametophytic self-incompatibility that is caused by the accumulation of non-functional S-haplotypes with disrupted pistil component (stylar-S) and/or pollen component (pollen-S) function. Genetic studies using diverse sour cherry germplasm identified non-functional S-haplotypes for which an equivalent wild-type S-haplotype was present in sweet cherry (Prunus avium), a diploid progenitor of sour cherry. In all cases, the non-functional S-haplotype resulted from mutations affecting the stylar component S-RNase or Prunus pollen component S-haplotype-specific F-box protein (SFB). This study determines the molecular bases of three of these S-haplotypes that confer unilateral incompatibility, two stylar-part mutants (S(6m2) and S(13m)) and one pollen-part mutant (S(13)'). Compared to their wild-type alleles, S(6m2)-RNase has a 1 bp deletion, S(13m) -RNase has a 23 bp deletion and SFB(13)' has a 1 bp substitution that lead to premature stop codons. Transcripts were identified for these three alleles, S(6m2)-RNase, S(13m)-RNase, and SFB(13)', however, these transcripts presumably result in altered proteins with a resulting loss of activity. Our characterization of natural pollen-part and stylar-part mutants in sour cherry along with other natural S-haplotype mutants identified in Prunus supports the view that loss of pollen specificity and stylar rejection evolve independently and are caused by structural alterations affecting the S-haplotype. The prevalence of non-functional S-haplotypes in sour cherry but not in sweet cherry (a diploid) suggests that polyploidization and gene duplication were indirectly responsible for the dysfunction of some S-haplotypes and the emergence of self-compatibility in sour cherry. This resembles the specific mode of evolution in yeast where accelerated evolution occurred to one member of the duplicated gene pair.

Alleles↗

PubMed1984

Genital warts and cervical cancer. V. The tissue basis of colposcopic change.

Histologic differences between subclinical papillomaviral infection and cervical intraepithelial neoplasia are quantitative rather than qualitative. Both entities are characterized colposcopically by acetowhite epithelium and aberrant surface capillaries. This study correlates five new colposcopic signs (variations in contour, thickness, color, vascular patterns, and iodine staining) with 12 histologic signs of human papillomaviral infection and 12 features of premalignant change. Acetowhitening and capillary abnormalities in minor colposcopic lesions are attributable to human papillomaviral disturbance of cell growth and maturation, seen histologically as parabasal layer proliferation, papillomatosis, koilocytosis , and dyskeratosis. Alteration in cell ploidy is usually minimal. Major colposcopic abnormalities reflect extensive disorganization of cell phenotype and tissue architecture, increased DNA content, and aneuploid stem cell populations. Intermediate colposcopic patterns generally denote polyploid lesions in which tissue changes are a composite of two reciprocal events: the extent of benign warty expression and the severity of premalignant change.

Animals↗

PubMed1984

Mechanisms of growth in hydatidiform moles.

Nuclear morphology and DNA synthesis were analyzed to determine the mechanism through which hydatidiform moles proliferate. Hydatidiform moles are characterized by a great variation in nuclear morphology and size. There are cells with small nuclei of variable size that have chromocenters and Barr bodies which do not undergo DNA synthesis or mitosis, as well as cells in the diploid range that have evenly stained nuclei that display numerous mitoses and a high proportion of interphase nuclei in the process of DNA synthesis. Nuclei in the medium range show classical endomitotic stages. Endomitotic nuclei in endometaphase do not label with tritiated thymidine; endoanaphase nuclei may have one or a few chromosomes labeled, and endotelophase nuclei are heavily labeled. Nuclei that are evenly stained and are in the medium- to giant-size range label differently, depending upon their size. Many of the medium-sized nuclei are labeled, indicating DNA synthesis; the large nuclei are rarely labeled, and the giant nuclei are never labeled. The growth of a hydatidiform mole appears to be the result of normal mitosis and cytokinesis, as well as polyploidization and accompanying cell enlargement achieved through endomitosis and endoreduplication.

Cells, Cultured↗

PubMed1992

Effects of chronic ethanol consumption on the rat parotid gland.

Two-month-old Wistar rats ingested 10% ethanol for 12 months. Their parotid glands were then compared with those of normal controls by light microscopy. They had extensive ductal and acinar oncocytic transformation; numerous atypical acinar cells showed anisocytosis, polyploidism and hyperchromatism, features that were absent in controls. Oncocytosis and atypical acinar cells have been reported in 2-3-yr-old ('senile') Wistar rats. Thus, chronic alcohol ingestion may produce cellular features resembling those observed in the parotid gland of 'senile' Wistar rats.

Alcoholism↗

PubMed1975

Inhibition of amylases from different origins by albumins from the wheat kernel.

The amylase activity of water extracts from 18 insect species, from 23 marine species and from 17 different species of birds and mammals was determined quantitatively. The inhibition of amylase in these extracts by three albumin fractions from the mature wheat kernel, which had been separated according to their molecular weights (60 000, 24 000 and 12 500 D), was determined as well. The inhibition activity of the three albumin fractions toward amylases extracted from a number of cereal species or from immature and germinating wheat kernel was also tested. The extracts from insects that are destructive of wheat grain and stored wheat products showed much higher amylase activities as compared to the other insect species that do not attack wheat and wheat products. On the basis of the effectiveness with which the three albumin fractions inhibit their activities, the amylase preparations tested were divided into susceptible, partially susceptible and resistent. Susceptible amylases, inhibited by any of the three albumin fractions, were found mainly in insects that attack wheat and in marine species. Partially susceptible amylases, inhibited by only one or two of the three albumin fractions, were present in a few avain and mammalian species including man. Resistent amylases were largely distributed in cereal, avian and mammalian species as well as in insect species that do not usually attack wheat grain or wheat flour products. At no stage of development, wheat alpha-amylase was inhibited by the albumin fractions from the mature kernel. The 12 500 dalton albumin fraction was the most effective in inhibiting insect amylases, but it was inactive toward avian and mammalian amylases. The 24 000 dalton albumin fraction was the most effective in inhibiting amylases from marine avian and mammalian species and inhibited as much as 33 amylases over 66 different amylases tested. It is suggested that protein inhibitors of amylase contributed to natural selection of polyploid wheats by giving some insect resistence to such wheats, even though some insect species were able to overcome this biochemical defense toa large degree by producing higher amylase activities.

Albumins↗

PubMed1975

The characterization of Euglena gracilis DNA by its reassociation kinetics.

The reassociation kinetics of Euglena gracilis DNA were carried out to determine the Cot 1/2 of the unique DNA (2000). The Cot 1/2 of the unique DNA and the amount of DNA per cell were used to show that this alga is not polyploid. Three kinetically definable classes of DNA were observed: a highly repetitive fraction, a middle repetitive fraction, and a non-repetitive fraction. Each fraction of DNA was characterized by its melting properties (Tm).

Animals↗

PubMed1982

Bradykinin induces hyperpolarizations in rat glioma cells and in neuroblastoma X glioma hybrid cells.

The effect of the nonapeptide bradykinin on the membrane potential of permanent cell lines from neural origin was studied. A hyperpolarizing response of 10-30 s duration was produced when bradykinin was iontophoretically applied onto polyploid rat glioma cells (clone C6-4-2). Starting from the resting membrane potential the peak value of the hyperpolarizing response was reached within 0.5-1.5 s. Then the potential returned more slowly to the original value. The hyperpolarization was associated with an approximately 50% decrease in membrane resistance. Neither Na+ nor Cl- seemed to be important for the hyperpolarizing response, since bradykinin elicited similar hyperpolarizations in cells exposed to media in which Na+ or Cl- were replaced by choline or isethionate, respectively. Ca2+ fluxes are unlikely to be involved, since the addition of D600 did not affect the hyperpolarizations induced by bradykinin. However, a 10-fold increase in the concentration of K+ in the medium reduced the amplitude of the hyperpolarization by 40 mV. Thus, the hyperpolarization induced by bradykinin is associated with decrease in membrane resistance which is likely to be caused by an increased K+-conductance. The glioma cells showed a desensitization upon repeated application of bradykinin. However, the sensitivity of the cells to bradykinin was restored after 3-8 min of incubation in the absence of bradykinin. Since an antagonist of bradykinin is not known, the specificity of the action of bradykinin is difficult to assess. Nevertheless, the hyperpolarizing response to bradykinin appears to be specific insofar as other peptides, i.e. lutoliberin, thyroliberin, neurotensin, substance P and apamin, exerted no effect on the membrane potential of the glioma cells. Bradykinin-elicited hyperpolarizations with characteristics similar to those described above could also be demonstrated in neuroblastoma X glioma hybrid cells, but not in multinucleated fibroblast cells.

Animals↗

PubMed1987

Atrial natriuretic polypeptide hormones induce membrane potential responses in cultured rat glioma cells.

Atrial natriuretic hormones (ANHs) applied to polyploid rat glioma cells induced hyperpolarizations of about 30 s duration, followed by depolarizations lasting 1-2 min. Repeated applications of the peptide resulted in desensitization. The reversal potential of -87 mV at an extracellular K+ concentration of 5 mM and the decrease of membrane resistance during the hyperpolarization indicate that K+ channels were activated by ANH. In these cells the fluorescence signal of 2-[(2-bis[carboxymethyl]amino-5-methylphenoxy)-methyl]-6-methoxy-8-bis [carboxymethyl]aminoquinoline (quin2) was not affected by ANH suggesting that ANH did not change the cytosolic Ca2+-activity.

Animals↗

PubMed1990

Activation of a K+ conductance by bradykinin and by inositol-1,4,5-trisphosphate in rat glioma cells: involvement of intracellular and extracellular Ca2+.

Extracellular application of bradykinin and injection of inositol-1,4,5-trisphosphate (Ins-P3) induced a hyperpolarization in polyploid rat glioma cells. Ins-1,4,5-P3 and Ins-2,4,5-P3 were effective but not Ins-4,5-P2, Ins-1,3,4,5-P4 and Ins-1,3,4,5,6-P5. The reversal potential of the hyperpolarizing response induced by bradykinin or by Ins-P3 increased to a comparable degree with increasing the extracellular K+ concentration. Certain blockers of K+ channels, for example charybdotoxin (5-50 nM), Ba2+ (5-20 mM), 4-aminopyridine (5-10 mM) and quinidine (0.1-0.5 mM) reversibly suppressed the membrane potential response to bradykinin or to Ins-P3; however, apamin (1 microM) and D-tubocurarine (0.5 mM) had no effect. Intracellular injection of EGTA made the glioma cells unresponsive to bradykinin. Superfusion of the cells with Ca2(+)-free medium gradually and reversibly abolished the response to bradykinin, but only slightly reduced the effect of Ins-P3. The Ca2+ channel blockers Co2+ (1-5 mM), Mn2+ (2-6 mM) and nifedipine (1-20 microM), but not desmethoxyverapamil (100 microM) inhibited the hyperpolarizing effect of bradykinin. The hyperpolarization induced by Ins-P3, however, was not influenced by Mn2+ (1-5 mM) or by Co2+ (7 mM). Injection of Ca2+ into the glioma cells induced a hyperpolarization susceptible to Ba2+ and quinidine. Treatment of glioma cells with an activator or with inhibitors of protein kinase C or with pertussis toxin did not affect the response to bradykinin. Incubation of the cells with the Ca2+ ionophore A23187 (0.1-1 microM) made the cells unresponsive to bradykinin and, somewhat less, to Ins-P3. At these concentrations the Ca2+ ionophore primarily depletes intracellular Ca2+ stores. In summary, bradykinin, via B2-receptors (blocked by [Thi5,8, D-Phe7]-bradykinin) activates a K+ conductance in glioma cells following a rise of cytosolic Ca2+ activity most likely due to Ins-P3-mediated release of Ca2+ from internal stores. Entry of extracellular Ca2+ appears also to be involved in this process.

Animals↗

PubMed1984

Elucidation of fertilization and development in a red alga by quantitative DNA microspectrofluorometry.

Crucial nuclear events throughout the life histories of red algae have eluded researchers. Use of the DNA fluorochrome 4',6-diamidino-2-phenylindole (DAPI) and microspectrofluorometry has now resolved the problems. In the parasitic red alga Choreocolax polysiphoniae (= Leachiella pacifica), the amounts of nuclear DNA during the processes of meiosis and fertilization are documented as well as the transfer of the newly formed zygote nucleus to the adjacent accessory cell. In this organism, the G2 period predominates in the cell cycle of vegatative and reproductive cells; many nondividing vegetative cells become highly polyploid. The results indicate that the use of various fluorochromes combined with microspectrofluorometric measurements of individual nuclei is valuable for study of many developmental problems in lower eukaryotes where the relatively small nuclear DNA content has made study with conventional dyes impossible.

Cell Nucleus↗

PubMed1983

Cytofluorometric DNA base determination for the investigation of heterochromatin and heterochromatin amplification.

The measurement of chromomycin A3/DAPI fluorescence ratios is shown to allow base content determinations in eu- and heterochromatic regions of interphase cell nuclei. The base content values obtained in chromocenters and euchromatin of Scilla sibirica agree with those measured earlier [12] on the band and non-band areas of the chromosomes of this species. In Sinapis alba three different heterochromatin types, with regard to base content, can be discerned. The heterochromatin amplification observed in the polyploid nuclei of Sinapis roots and hypocotyl involves either all three heterochromatin types, with little resulting change of the total nuclear base content, or only one or the other of them, with a measurable shift of the base content.

Adenine↗

PubMed1985

Cell cycle effects of iron depletion on T-47D human breast cancer cells.

T-47D human breast cancer cells grown in culture medium containing low concentrations of fetal calf serum (FCS) proliferated very slowly, with an accumulation of cells in the G2 phase of the cell cycle, increased polyploid cells, and increased expression of transferrin receptors. Cell proliferation was stimulated by the addition of human transferrin or ammonium ferric citrate to the medium. Growth inhibition and accumulation of G2-phase cells could also be produced in T-47D cells grown in medium containing 10% FCS by the addition of the iron chelator, desferrioxamine. It is concluded that cellular deprivation of iron and/or transferrin is the major cause of reduced proliferation rates and G2-phase arrest which accompany the culture of these cells in medium supplemented with low concentrations of FCS.

Animals↗

PubMed1986

Post-meiotic DNA synthesis in nocodazole-blocked nuclei during conjugation of Tetrahymena thermophila. Induction of polyploidy in the micronucleus.

The formation of single, polyploid micronuclei was induced during conjugation of Tetrahymena thermophila with Nocodazole (ND) according to Kaczanowski et al. The increase in DNA content in these nuclei was measured cytophotometrically in conjugating pairs continuously exposed to the drug. ND-treated micronuclei ('restitution nuclei') undergo two complete rounds of DNA replication and enter the third at the time of pair separation. The DNA content of these micronuclei in late pairs was in the range 16-30C (mean 20C). This amount was similar to the sum of the DNA content of all post-meiotic products during normal conjugation at about the same stage. Thus the increase in DNA content in 'restitution' nuclei reflects some intrinsic ability of nuclei in pairing cells to replicate DNA independently of nuclear division.

Animals↗

PubMed1992

Skin fibroblasts from aged Fischer 344 rats undergo similar changes in replicative life span but not immortalization with caloric restriction of donors.

We have compared the in vitro replicative life span and characteristics of immortalization of skin fibroblast cultures derived from ad libitum-fed and caloric-restricted Fischer 344 rats of 6, 24, and 29 months of age. Cells from all 6-, 24-, and 29-month-old animals showed a gradual decline in proliferative potential as evidenced by decreases in harvest density, in the fraction of cells initiating DNA synthesis, and in the number of population doublings per passage. These declines were accompanied by morphological changes including cell enlargement. The replicative life span prior to immortalization decreased significantly with donor age (P less than 0.0001), while caloric restriction had no effect on the cumulative population doubling level. Prior to immortalization mitotic cells from all cultures showed a normal rat karyotype. Postcrisis cultures tended to have more polyploid cells but there were no characteristic or specific chromosomal changes found in the cells with an immortalized phenotype. Interestingly, fibroblasts derived from caloric-restricted animals had a significantly slower growth rate through the tenth week after immortalization (P less than 0.005). When these cultures were seeded at one-quarter the normal seeding density, to favor the outgrowth of the fastest growing cells, a population with a more "transformed" phenotype emerged.

Age Factors↗

PubMed1988

Changes in nuclear DNA content and cell size of injured human corneal endothelium.

To understand how human corneal endothelium compensates for cell loss, nuclear DNA-cytofluorometry and cell morphometry were carried out on injured corneal endothelium. The examined corneas included two cases of keratoconus complicated with acute hydrops and one without acute hydrops, two cases of herpetic keratitis, one case of post-intracapsular cataract extraction (post-ICCE) and one case of luetic keratitis. The endothelial cell layer was separated from Descemet's membrane and double-stained with Rhodamine-labeled wheat germ agglutinin-lectin (WGA) and 4',6-diamidino-2-phenylindole dihydrochloride (DAPI). The area of each cell was measured with a color image analyser and compared with its cytofluorometric nuclear DNA content. The endothelium in apparently intact regions of the diseased corneas showed the same DNA-ploidy pattern and cell area as the physiological corneas. However, endothelial cells in injured regions had greater area, even in diploidy, than in presumably normal ones and showed a larger number of hyperploid cells ranging from 4C to 36C. Hyperploid cells consisted of many multinucleates and few polyploidies and had extremely large and bizarre cytoplasm. All injured corneas were accompanied by cells with numerous micronuclei. A few asymmetrical 4C-binucleates (with DNA values such as 1.3 plus 2.6C) appeared in the case of the post-ICCE. It is concluded that damage to human corneal endothelial cells in vivo results in cell enlargement with or without DNA synthesis. Those changes appear more severe in diseased corneas than in the situation of physiological aging which we have reported previously. In severe cases, micronuclei, polyploid cells and multinucleated giant cells are frequent, thereby suggesting a possible long-persistent metabolic impairment of the endothelium after severe damage to the cornea.

Adolescent↗