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PubMed2005

Chlorhexidine digluconate induces mitotic recombination in diploid cells of Aspergillus nidulans.

UNLABELLED: Chlorhexidine digluconate (1,1'-hexamethylene-bis[(5-p-clorophenyl)-biguanide]) is a bisbiguanidine antiseptic, used to decrease plaque formation and to control periodontal diseases. The determination of the frequency of mitotic crossing-over constitutes a very important method for detecting carcinogenic agents. OBJECTIVE: The recombinogenic potential of chlorhexidine digluconate was evaluated on Aspergillus nidulans by the production of cells homozygous for the following nutritional markers: riboA1, pabaA124, biA1, methA17 and pyroA4. METHOD: A. nidulans was exposed to three concentrations of chlorhexidine digluconate (1, 5, and 10 microM). RESULTS: Inhibition of colony development, conidiophore morphological alteration (cytotoxic effect), and the recombinogenic effect, indicated by homozygotization index (HI) values higher than 2.0, were observed for all concentrations of chlorhexidine digluconate. A homozygous pyro+//pyro+ diploid strain and a diploid homozygous for the recessive w gene were isolated from UT448//A757 diploid treated with chlorhexidine digluconate, emphasazing its recombinogenic potential. CONCLUSION: Although, beneficial effects of chlorhexidine, as an antiseptic agent, are reported in the literature, our results revealed that chlorhexidine digluconate, at less levels lowered those used clinically, caused toxic and recombinogenic effects on diploid A. nidulans strain.

Anti-Infective Agents↗

PubMed2001

Serotype AD strains of Cryptococcus neoformans are diploid or aneuploid and are heterozygous at the mating-type locus.

Cryptococcus neoformans is a pathogenic basidiomycete with a defined sexual cycle involving mating between haploid yeast cells with a transient diploid state. C. neoformans occurs in four predominant serotypes (A, B, C, and D), which represent different varieties or species. Rare clinical and environmental isolates with an unusual AD serotype have been reported and suggested to be diploid. We found by fluorescence-activated cell sorter analysis that serotype AD strains are aneuploid or diploid. PCR analysis with primers specific for serotype A or D alleles of the CNA1, CLA4, and GPA1 genes revealed that both alleles are often present in serotype AD strains. PCR analysis with primers specific for genes in the MATa or MATalpha mating-type loci revealed that serotype AD strains are heterozygous for the mating-type locus. Interestingly, in several serotype AD strains, the MATalpha locus was derived from the serotype D parent and the MATa locus was inherited from a serotype A parent that has been thought to be extinct. Basidiospores from a self-fertile serotype AD strain bearing the putative serotype A MATa locus showed a very low viability ( approximately 5%), and no fertile serotype A MATa strain could be recovered. Serotype AD strains were virulent in a murine model. Hybrid AD strains could readily be isolated following a laboratory cross between a serotype A strain and a serotype D strain. In summary, serotype AD strains of C. neoformans are unusual aneuploid or diploid strains that result from matings between serotype A and D strains. Self-fertile isolates fail to undergo normal meiosis because of genetic divergence. Our findings further suggest that serotype A MATa strains may exist in nature.

Aneuploidy↗

PubMed1977

Demonstration of dual rhinovirus infection in humans by isolation of different serotypes in human heteroploid (HeLa) and human diploid fibroblast cell cultures.

The ability to isolate rhinoviruses in human heteroploid cell cultures was investigated by inoculating HeLa cells (HeLa M) with specimens previously shown to be positive in human diploid cell cultures. The 135 positive specimens selected were representative of 22 different rhinovirus types, and 4 to 9 specimens were available for each serotype. Specimens were inoculated into human diploid fetal tonsil fibroblasts (FT), HeLa cells with 30 mM Mg2+, and HeLa cells without increased Mg2+. One hundred twelve rhinovirus strains (83%) were reisolated in FT cells, whereas 76 rhinovirus strains (56%) were recovered in HeLa cells with 30 mM Mg2+. All strains recovered in FT were the same serotype as that originally recovered in diploid cells, but five of the HeLa cell isolates (3.7% of total specimens) were different serotypes, indicating dual rhinovirus infections. Four rhinovirus serotypes, (3, 42, 48, and 70) were recovered in HeLa but not in diploid cells; these serotypes were rare in our previous studies. Isolation of rhinovirus in FT cells was usually accomplished at first passage, whereas rhinovirus cytopathic effects in HeLa cells were not observed at first passage, but required one, two, or (rarely) three blind passages. Only 28 rhinoviruses (21%) were recovered in HeLa cells without increased Mg2+; however, three serotypes, types 16, 36, and 58, were recovered as effectively in HeLa cells, with or without added Mg2+, as they were in FT cells. In general, rhinoviruses were less efficiently recovered in HeLa cells; however, certain serotypes may be detected better by HeLa cells.

Cell Line↗

PubMed1974

Antiserum inactivation of electrophoretically purified M13 diploid virions: model for the F-specific filamentous bacteriophages.

Antiserum inactivation experiments were carried out on electrophoretically purified diploid virions from a cross between two complementing amber mutants of phage M13. The total (homozygous plus heterozygous) diploid population, assayed on a permissive host where only one genome is needed for plaque formation, was inactivated at the same rate as haploids. Heterozygous diploids, assayed on a nonpermissive host, where both genomes are needed for plaque formation, were twice as sensitive as haploids and the total diploid population. These results have led us to propose a model for serum inactivation of the F-specific filamentous phages. According to this model, phage-neutralizing antibodies attach anywhere along the length of the phage and allow the phage to penetrate only up to the first bound antibody molecule.

Adsorption↗

PubMed2000

Meiotic recombination in sexual diploid and apomictic triploid dandelions (Taraxacum officinale L.).

Taraxacum officinale L. (dandelion) is a vigorous weed in Europe with diploid sexual populations in the southern regions and partially overlapping populations of diploid sexuals and triploid or tetraploid apomicts in the central and northern regions. Previous studies have demonstrated unexpectedly high levels of genetic variation in the apomictic populations, suggesting the occurrence of genetic segregation in the apomicts and (or) hybridization between sexual and apomictic individuals. In this study we analysed meiosis in both sexual diploid and apomictic triploid plants to find mechanisms that could account for the high levels of genetic variation in the apomicts. Microscopic study of microsporocytes in the triploid apomicts revealed that the levels of chromosome pairing and chiasma formation at meiotic prophase I were lower than in that of the sexual diploids, but still sufficient to assume recombination between the homologues. Nomarski DIC (differential interference contrast) microscopy of optically cleared megasporocytes in the apomicts demonstrated incidental formation of tetrads, which suggests that hybridization can occur in triploid apomicts.

Animals↗

PubMed2005

Toward the development of highly homozygous diploid potato lines using the self-compatibility controlling Sli gene.

Cultivated diploid potatoes (2n = 2x = 24) are self-incompatible, but can be altered to become self-compatible using the Sli gene. Previously, a diploid clone 97H32-6 was selfed up to S3 using the Sli gene. To explore the usefulness of the Sli gene for the production of highly homozygous diploid potatoes, 2 S4 families from the above 97H32-6 derived S3 lines (inbred series A) and 3 S5 families by continuous selfings from a different F1 (= S0) plant (inbred series B) were developed. The level of heterozygosity and the location of heterozygous loci on the genetic map were investigated using RFLP and AFLP markers. The average heterozygosity levels of the originally heterozygous loci decreased from 100% in S0 to 10.7% in S4 and 8.6% in S5 (inbred series A and B, respectively). The average rate of reduction in heterozygosity per generation (38.4% and 38.5% for inbred series A and B, respectively) was lower than the theoretically expected rate (50%). However, none of the loci or chromosome sections was exclusively heterozygous in the advanced self-progeny. Thus, highly homozygous and seed-propagated diploid potatoes could be obtained by repeated selfing using the Sli gene.

Chromosome Mapping↗

PubMed1983

Chromosome pairing in female and male diploid and polyploid anurans (Amphibia) from South America.

Chromosome pairing in females and males of diploid (2n = 22) and tetraploid (2n = 44) Odontophrynus americanus and diploid Ceratophrys cranwelli (2n = 26) and tetraploid C. ornata (2n = 104) showed that diploid females formed more chiasmata per paired arm than diploid males and polyploids of both sexes. There was a reduction in the level of recombination in female polyploids by forming multivalents with terminal chiasmata. The reduction reflected a change in the genetic control of pairing in females after polyploidization.

Animals↗

PubMed2005

Genome evolution of allopolyploids: a process of cytological and genetic diploidization.

Allopolyploidy is a prominent mode of speciation in higher plants. Due to the coexistence of closely related genomes, a successful allopolyploid must have the ability to invoke and maintain diploid-like behavior, both cytologically and genetically. Recent studies on natural and synthetic allopolyploids have raised many discrepancies. Most species have displayed non-Mendelian behavior in the allopolyploids, but others have not. Some species have demonstrated rapid genome changes following allopolyploid formation, while others have conserved progenitor genomes. Some have displayed directed, non-random genome changes, whereas others have shown random changes. Some of the genomic changes have appeared in the F1 hybrids, which have been attributed to the union of gametes from different progenitors, while other changes have occurred during or after genome doubling. Although these observations provide significant novel insights into the evolution of allopolyploids, the overall mechanisms of the event are still elusive. It appears that both genetic and epigenetic operations are involved in the diploidization process of allopolyploids. Overall, genetic and epigenetic variations are often associated with the activities of repetitive sequences and transposon elements. Specifically, genomic sequence elimination and chromosome rearrangement are probably the major forces guiding cytological diploidization. Gene non-functionalization, sub-functionalization, neo-functionalization, as well as other kinds of epigenetic modifications, are likely the leading factors promoting genetic diploidization.

Chromosomes, Plant↗

PubMed1986

Suppression of tumorigenicity in somatic cell hybrids. III. Cosegregation of human chromosome 11 of a normal cell and suppression of tumorigenicity in intraspecies hybrids of normal diploid x malignant cells.

Tumorigenicity assays of 48 intraspecies hybrids between human carcinoma-derived cells of the D98AH2 (HeLa) cell line and normal human diploid cells revealed that most are nontumorigenic in nude mice. Chromosome analysis revealed that these hybrids contained four chromosomes 11, presumably two from each parental cell. Their tumorigenic segregants sometimes, and their tumors always, had lost one or two copies of chromosome 11 (Klinger and Kaelbling, 1986). In this report we present evidence from analyses of DNA restriction fragment length polymorphic (RFLP) markers for the parental cell origin of the 11 which confirms that the four chromosomes 11 of the nontumorigenic hybrids consisted of two from each cell parent, and most notably, that one No. 11 of the diploid parental cell is always absent in cells of tumors that arise when the tumorigenic hybrids are injected into nude mice. We also found that both Nos. 11 of the D98 cells are identical at many RFLP sites on the short arm suggesting that loss of heterozygosity of the 11, or at least of the short arm of the 11, had occurred. Chromosome 11 of the diploid cells thus appears to carry alleles that suppress the tumorigenic potential of the D98 cells when present in two copies, but not in one. It remains to be seen if other chromosomes of the diploid cell effect suppression in concert with the 11.

Animals↗

PubMed1986

Diploid spermatids: a manifestation of spermatogenic impairment in XOSxr and T31H/+ male mice.

Microdensitometry of Feulgen-stained spermatogenic cell preparations from six XOSxr and four T31H/+ male mice revealed large numbers of spermatids with a diploid amount of DNA. In XOSxr mice, where the diploid spermatids usually constituted the majority of the spermatid population, there were large differences from mouse to mouse in the proportion of diploid spermatids (range, 35%-94%). There were large losses of both haploid and diploid spermatids during spermiogenesis, and the later condensed spermatids of both types were grossly misshapen. It is suggested that the omission of one meiotic division, and the other spermiogenic anomalies may be manifestations of a meiotic "quality control" mechanism that destroys the products of those pachytene spermatocytes which have unsynapsed or incompletely synapsed chromosomes.

Animals↗

PubMed2001

Temperature dependence in proliferation of tetraploid Meth-A cells in comparison with the parent diploid cells.

The temperature dependency for the growth of tetraploid Meth-A cells established from diploid cells was examined in comparison with the parent diploid cells. Proliferation of the tetraploid cells was markedly suppressed below 35 degrees C. At above 40 degrees C, both the diploid and tetraploid Meth-A cells ceased growing. Flow cytometry (FCM) analysis showed that the hyperploid cell fraction increased in the tetraploid Meth-A cell population at low temperatures. The fluidity of cell membranes at different temperatures was measured by means of electron spin resonance (ESR), and it was almost the same between the diploid and tetraploid Meth-A cells. It was suggested that the decreased proliferation below 35 degrees C of the tetraploid Meth-A cells might be due to the increased volume of the cells.

Aneuploidy↗

PubMedDate not supplied

Alkaloid spectrum in diploid and tetraploid hairy root cultures of Datura stramonium.

Hairy root cultures were obtained from diploid and induced tetraploid plants of Datura stramonium and analyzed by gas chromatography/mass spectrometry. Twenty alkaloids (19 for diploid and 9 for tetraploid hairy root cultures) were identified. A new tropane ester 3-tigloyloxy-6-propionyloxy-7-hydroxytropane was identified on the basis of mass spectral data. Hyoscyamine was the main alkaloid in both diploid and tetraploid cultures. In contrast to diploid hairy roots, the percentage contributions of the alkaloids, with exceptions for hyoscyamine and apoatropine, were higher in the total alkaloid mixture of tetraploid hairy roots.

Alkaloids↗

PubMed2006

Comparison of gene representation between diploid and triploid Paragonimus westermani by expressed sequence tag analyses.

Expressed sequence tag (EST) analysis of the diploid and triploid Paragonimus westermani genes was done to have a rapid and informative outlook of the gene-expression profiles of the parasites. Totals of 506 and 505 ESTs were generated from the diploid and triploid P. westermani cDNA libraries. Based on the BLASTx search results of the diploid P. westermani ESTs, 308 (60.9%) matched significantly with formerly identified genes and 198 (39.1%) showed no significant homology in the GenBank database. A similar homology pattern was shown from the triploid EST BLASTx search results with 346 (68.5%) sharing homology with previously identified genes and 159 (31.5%) showing no significant homology. The EST data from both libraries were analyzed and grouped into 9 categories. Comparison of the 2 EST pools revealed high similarities among the categories of the significantly matched genes. Single genes matched repeatedly were also observed in the 2 EST data. Some genes were found that are not yet characterized in P. westermani; these genes were matched by both the diploid and triploid ESTs. Further study of these genes may provide us with more understanding on the parasite's biology and their specific functions in the 2 strains.

Animals↗

PubMed2000

An anchored AFLP- and retrotransposon-based map of diploid Avena.

A saturated genetic map of diploid oat was constructed based on a recombinant inbred (RI) population developed from a cross between Avena strigosa (Cereal Introduction, C.I. 3815) and A. wiestii (C.I. 1994). This 513-locus map includes 372 AFLP (amplified fragment length polymorphism) and 78 S-SAP (sequence-specific-amplification polymorphism) markers, 6 crown-rust resistance loci, 8 resistance-gene analogs (RGAs), one morphological marker, one RAPD (random amplified polymorphic DNA) marker, and is anchored by 45 grass-genome RFLP (restriction fragment length polymorphism) markers. This new A. strigosa x A. wiestii RI map is colinear with a diploid Avena map from an A. atlantica x A. hirtula F2 population. However, some linkage blocks were rearranged as compared to the RFLP map derived from the progenitor A. strigosa x A. wiestii F2 population. Mapping of Bare-1-like sequences via sequence-specific AFLP indicated that related retrotransposons had considerable heterogeneity and widespread distribution in the diploid Avena genome. Novel amplified fragments detected in the RI population suggested that some of these retrotransposon-like sequences are active in diploid Avena. Three markers closely linked to the Pca crown-rust resistance cluster were identified via AFLP-based bulk-segregant analysis. The derived STS (sequence-tagged-site) marker, Agx4, cosegregates with Pc85, the gene that provides resistance specificity to crown-rust isolate 202 at the end of the cluster. This framework map will be useful in gene cloning, genetic mapping of qualitative genes, and positioning QTL (quantitative trait loci) of agricultural importance.

Avena↗

PubMed1975

[Kinetics of the synthesis of nucleic acids in haploid and diploid loach embryos].

Al kinetic analysis of incorporation of the mixture of 3H-nucleosides in the nucleic acid fractions was carried out to examine the mechanisms of compensation of the genetic material deficiency. Both the haploid and diploid embryos of the loach (Misgurnus fossilis L.) were analyzed. When comparing the DNA and RNA syntheses, the level of phosphorylation (nucleotide pool) in the both genetic variants was under control. The rate of incorporation of the labelled nucleosides in DNA was shown to be higher in haploids at the early developmental stages than in diploids but later it became the same. The increased level of DNA replication in the early haploid embryos was due to the compensatory increase of the cell number in them as compared with the diploid ones. The rate of total RNA synthesis corrected by the differences in the rate of nucleoside phosphorylation varied directly with the degree of ploidy at the blastula stage; at the gastrula stage the value of RNA synthesis per haploid genome was compensated, and at the stage of organogenesis the production of total RNA, as calculated per cell, became in haploids even higher than in diploids. The data obtained suggest the essential changes in the patterns of RNA synthesis control during development.

Age Factors↗

PubMed1992

Modification of tumor ploidy level via the choice of tissue taken as diploid reference in the digital cell image analysis of Feulgen-stained nuclei.

We studied the influence of five cell nucleus populations taken as diploid standards with respect to the normalization of a human breast carcinoma. Four normal human tissues (lymphocytes, thyroid, liver, and bladder specimens) were taken as external standards, while the normal breast cells "contaminating" the tumor were taken as the internal diploid standard. Nuclear size and nuclear DNA assessments were performed by means of a cell image processor computing the parameters on Feulgen-stained nuclei from fresh imprint smears fixed in an ethanol-formalin-acetic acid mixture. Our results demonstrate that the choice of normal tissue as the diploid standard markedly influences the ploidy level of breast carcinoma. Normalization according to the lymphocytes led to our obtaining a major hyposextaploid G0-G1 DNA peak in the breast cancer. Using thyroid and liver cells as a standard, we obtained a major pentaploid and sextaploid G0-G1 peak, respectively. Using bladder cells or the normal contaminating breast cells within the tumor, we obtained a major tetraploid G0-G1 peak. Finally, the normalization of the normal bladder cells against the liver cells led to our obtaining a near triploid bladder specimen. The reverse feature was also observed, e.g., the obtaining of biologically nonsensical hypodiploid liver cells after normalization against the normal bladder cells. Such postnormalization variations in ploidy level depend upon the mean nuclear size and the mean nuclear DNA content of the normal tissue taken as diploid standard.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗

PubMed2003

[The genetic control of cell growth and development in yeast Saccharomyces cerevisiae. Disturbed sporulation in diploids with decreased activity of the Ras/cAMP signal transduction pathway].

Seven haploid strains (four with the MAT alpha mating type and three with the MATa mating type) were selected from the Peterhof genetic collection of yeast. Previous phenotypic analysis assigned six of these strains to a physiological group of strains with a lower activity of the Ras/cAMP signal transduction pathway. The haploids were crossed, and the resulting 12 diploids showed higher glycogen accumulation, tolerance to heat shock and nitrogen starvation, and sporulation in complete media. Ten of the diploids expressed the hypersporulation phenotype (higher sporulation efficiency). The phenotypic characters of these ten diploids suggested a reduced activity of the Ras/cAMP pathway. All 12 diploids were tested for sporulation and production of two groups of asci (those with one or two spores and those with three or four spores) as dependent on culture conditions (21, 30, or 34 degrees C; standard sporulation medium or a complete medium containing potassium acetate or glycerol in place of glucose). Sporulation proved to depend on temperature and medium composition. The results are collated with the data on yeast phenotypes associated with a lower activity of the Ras/cAMP signal transduction pathway.

Culture Media↗

PubMed1992

[Comparative analysis of amino acids of metacercaria and larvae of diploid and triploid of Paragonimus westermani].

The diploid type of Paragonimus westermani in Heilongjiang Province and triploid type of P. westermani in Liaoning Province were examined for amino acids by high performance liquid chromatography (HPLC). Eleven kinds of amino-acids of diploid type and 15 kinds of triploid type were found in metacercaria; 15 kinds amino acids of diploid type and 16 kinds of triploid type were detected in larvae. The amino acids were more abundant in larvae than in metacercaria and more in the triploid than in the diploid type. The predominant amino acids were cystine and glutamic acid.

Amino Acids↗