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PubMed1979

Aflatoxins and anthraquinones from diploids of Aspergillus parasiticus.

Three spore colour, two mycelial colour and 12 auxotrophic mutants were isolated from an aflatoxigenic strain of Aspergillus parasiticus. These mutants and heterozygous diploids formed by pairwise combinations of auxotrophs were assayed for aflatoxin production; norsolorinic acid and versicolorin A production were also assayed in the diploids. In general, introduction of an auxotrophic marker lowered aflatoxin production in haploids. The green-spored, prototrophic diploids resembled haploid wild-type strains in that they produced high levels of aflatoxin, low levels of versicolorin A, and no detectable norsolorinic acid. Parasexual analysis of segregants from four heterozygous diploids was hampered by the uniform conidiospore diameter of haploids and diploids and by the non-random recovery of genotypes among somatic segregants with and without treatment with p-fluorophenylalanine. Nevertheless, this technique is useful for recombinational analysis of mutants blocked in aflatoxin synthesis. The fortuitous association of mycelial pigmentation with certain blocked aflatoxin mutants should prove useful in future analyses of the genetics and biosynthesis of these economically important secondary metabolites.

Aflatoxins↗

PubMed1994

Double labelling to obtain S phase subpopulations: application to determine cell kinetics of diploid cells in an aneuploid tumour.

We studied the cell kinetics of the murine mammary carcinoma MCa-K using iododeoxyuridine (IdUrd) and chlorodeoxyuridine (CldUrd) given at different times as independently detectable labels of S phase cells. The presence of IdUrd and CldUrd, and the amount of DNA were measured by three-colour flow cytometry making it possible to define three subpopulations within S phase and to measure the progression through the cell cycle during the time following labelling. In DNA histograms of these subpopulations, the diploid and aneuploid cells (which had a DNA index of 1.7) are essentially completely separated. From appropriate combinations of cells labelled with IdUrd only, CldUrd only, or both, it was possible to construct separate DNA distributions for the labelled diploid and aneuploid cells at the times of administration of each label. The kinetics of the diploid and aneuploid cells could be calculated for individual tumours from these two time points without having to make corrections for the presence of the second population. The diploid and aneuploid populations had indistinguishable S and G2 + M phase durations, T(S) and T(G2 + M), of about 9 and 2 h; however, the potential doubling time values for the aneuploid and diploid populations were 30.2 and 101.2 h respectively.

Aneuploidy↗

PubMed2004

RAPD analysis of diploid and tetraploid populations of Aronia points to different reproductive strategies within the genus.

Plant breeding in black chokeberry (Aronia melanocarpa) is based mainly on seedlings derived from domesticated Russian plants. Previous studies have, however, demonstrated very low levels of phenotypic variation within this gene pool. The present investigation was undertaken in order to study the genetic structure in native populations growing in North America. Random amplified polymorphic DNA (RAPD) marker variation was analysed in eight populations (three or five mother plants/population and five seedlings/mother plant) and compared with the variation in four cultivars and 15 seedlings derived from a Russian plantation. The four cultivars and all the Russian seedlings turned out to have identical RAPD profiles. In the native plant material, there were two types of mother plants: diploid plants that produced very heterogeneous offspring and tetraploid plants that produced homogeneous offspring. Partitioning of variability based on Shannon's diversity index attributed approx. 22% of the variation to the among-population level in diploids, compared to approx. 55% in the tetraploids. However, the diploid populations and the tetraploid populations did not differ significantly in within-population variation. These results prompted a second set of RAPD analyses, which were carried out on offspring obtained through open pollination of the initially examined material when growing in an experimental field. The analyses showed that tetraploid plants produced tetraploid offspring that, with few exceptions, were identical, indicating apomixis, whereas offspring of diploid plants were diploid or triploid, and highly heterogeneous, indicating outcrossing. Presumably, the tetraploid form of Aronia is an allopolyploid, with A. melanocarpa as one of the parents.

Canada↗

PubMed1967

Diploid hybridization in a heterothallic haploid yeast, Saccharomyces rouxii.

By crossing of a heterothallic haploid yeast, Saccharomyces rouxii, we have succeeded in obtaining diploid hybrids. This paper shows one possible method of breeding heterothallic haploid yeasts for industrial application. S. rouxii is highly salt-tolerant and plays an important role in shoyu and miso fermentation. Therefore, genetic improvements of the properties are of commercial importance. Since newly isolated S. rouxii could neither conjugate nor sporulate on sporulation media commonly used, a suitable medium for conjugation and sporulation of S. rouxii was firstly investigated. A 5% NaCl Shoyu-koji extract agar was found to be most efficient. Next, we tried to get diploid strains by mass culture of two mating types on the conjugation medium, but several phenomena made this difficult: (i) zygotes quickly sporulated before budding; (ii) several zygotes showed terminal budding, but the buds could not grow into diploid cells, suggesting they would be heterocaryon; and (iii) a few zygotes lost their viability. After trying to isolate and cultivate a large number of zygotes in various combinations of crossing by micromanipulation, we fortunately recognized that large cells arose from some combinations. The analysis of ploidy suggested that the large cells would be diploid. Also, they showed sporulation of typical Saccharomyces, i.e., two to four spores in an unconjugated ascus. The diploid strains thus obtained were highly salt-tolerant and stable in liquid medium. Therefore, the procedure presented here would be effective for breeding salt-tolerant S. rouxii.

Conjugation, Genetic↗

PubMed1970

Conservation and transfer of Escherichia coli genetic segments by partial diploid Hfr strains of Salmonella typhosa.

Heterozygous, partial diploid hybrids were obtained in a Salmonella typhosa Hfr strain by using it as the recipient in a mating with the Escherichia coli Hfr donor WR2004 (O...proA...leu). Three of these S. typhosa Hfr hybrids were observed to mobilize and transfer the diploid E. coli genes, at high frequencies, to an E. coli recipient. The gradient of transfer frequencies of E. coli markers from these S. typhosa Hfr hybrids was similar to that observed with E. coli Hfr WR2004, from which they were derived. Interrupted matings with one of these S. typhosa Hfr hybrids, designated WR4272, showed the entry times for the proA, thr(-)leu, and argB E. coli diploid markers to be identical to the times obtained for these markers with E. coli Hfr WR2004. Also, the pattern of unselected inheritance of the diploid E. coli markers of S. typhosa Hfr hybrid WR4272 was similar to that observed with the chromosomal markers of E. coli Hfr WR2004. It was concluded that S. typhosa Hfr hybrid WR4272 contains, in addition to its Salmonella genome, a physically continuous E. coli chromosomal segment which is genetically complete from proA to at least the strA locus. The two other S. typhosa Hfr hybrids, on the basis of transmission frequency gradients, appeared to contain a continuous E. coli diploid segment complete from proA through the fuc locus. Other classes of S. typhosa Hfr hybrids, derived from mating with E. coli Hfr WR2010 (O...tna...xyl), were also observed to transfer E. coli genes at high frequency.

Chromosome Mapping↗

PubMed1973

Conservation of Salmonella typhimurium deoxyribonucleic acid in partially diploid hybrids of Escherichia coli.

Partially diploid Escherichia coli K-12 hybrids recovered from mating with a Salmonella typhimurium Hfr strain were found to differ with respect to the manner in which they conserved the added Salmonella deoxyribonucleic acid (DNA). Five of the diploid hybrids examined appeared to maintain the Salmonella DNA as part of a functional F-merogenote; these hybrids were sensitive to the male-specific phage, R-17, responded as males to the female-specific phage, phiII, and transferred their inherited Salmonella genetic markers at high frequency in conjugation experiments. Six diploid hybrids were observed which were not sensitive to R-17, and from which the added Salmonella DNA was not transmissible in conjugation tests; nevertheless, these hybrids responded as males to phiII, and the Salmonella chromosomal fragments were conserved in them as parts of supercoiled, circular DNA elements. It was concluded that these circular DNA elements were defective F-merogenotes, unable to direct the synthesis of F-pili. Three diploid hybrids were found which were not sensitive to R-17, and which responded as females to phiII; no circular DNA was found in them, and it was concluded that their conservation of the Salmonella genetic fragments was accomplished in some manner which did not involve association with F or assumption of the supercoiled circular configuration. Other partially diploid hybrids were observed which appeared similar to these latter three hybrids with regard to their conservation of the Salmonella DNA, but which also contained an infecting F-factor; in these hybrids, both genetic and molecular experiments indicated that the unstably conserved Salmonella DNA was not associated physically with the F-factor.

Carbon Isotopes↗

PubMed1963

SMALL-CELL SEGREGANTS FROM A POSSIBLY HOMOZYGOUS DIPLOID STRAIN OF ESCHERICHIA COLI.

Ogg, James E. (Colorado State University, Fort Collins) and Ronald D. Humphrey. Small-cell segregants from a possibly homozygous diploid strain of Escherichia coli. J. Bacteriol. 85:801-807. 1963.-Evidence was presented to show that a homozygous possibly diploid strain of Escherichia coli, when grown in a chemically defined medium under the conditions described in this report, will yield small-cell segregants that have haploid characteristics. The segregants have one-half as much deoxyribonucleic acid per cell as the diploid, give exponential survival curves when exposed to X rays, and have fermentative characteristics similar to the original haploid parent strain of the homozygous diploid strain. No detectable changes in surface antigens were associated with the segregation phenomenon. The haploidlike segregants can be converted to the diploid radiation-resistant state by growing them in the presence of camphor vapors.

Colorado↗

PubMed1963

EFFECT OF HAPLOID OR DIPLOID CONSTITUTION OF ESCHERICHIA COLI ON FORMIC HYDROGENLYASE ACTIVITY.

Olsen, Ronald H. (Colorado State University, Fort Collins) and James E. Ogg. Effect of haploid or diploid constitution of Escherichia coli on formic hydrogenlyase activity. J. Bacteriol. 86:494-498. 1963.-Phenotypic differences occurring between haploid and presumed diploid strains of Escherichia coli containing homologous genetic material have been observed. In a growth medium containing glucose and Casamino Acids, formic hydrogenlyase (FHL) activity was induced in haploid strains but not in diploid cells. Other differences were noted when haploid and diploid resting-cell suspensions were assayed for their ability to induce maximal FHL activity. For FHL activity, diploid induction lags were significantly longer, and maximal inducible rates were lower than those observed for haploid strains.

Colorado↗

PubMed1982

Propranolol, atenolol, and trifluoperazine reduce the spontaneous occurrence of meiotic diploid products in Saccharomyces cerevisiae.

The effect of atenolol, propranolol, trifluoperazine, and caffeine on the occurrence of meiotic diploid and disomic products in Saccharomyces cerevisiae was investigated. We demonstrated that atenolol, propranolol, and trifluoperazine reduce the occurrence of meiotic diploid products and that propranolol also slightly decreases the spontaneous frequency of disomics. On the other hand, caffeine appears to be a powerful inducer of diploid meiotic products, but also shows a lesser effect on disomic induction. Since spontaneous or caffeine-induced diploids arise from a failure of the second meiotic division, it appears that the target of these drugs is at the beginning of the second meiotic division. The only common effect of trifluoperazine and propranolol, mainly investigated in mammals, was an inhibition of calmodulin activity via direct interaction. We tend, therefore, to believe that calmodulin activity must be a crucial point for the second meiotic division to begin. The increased induction of diploids, due to caffeine, may be interpreted as a consequence of an increased cyclic AMP level.

Atenolol↗

PubMed2006

Chromosome structural changes in diploid and tetraploid A genomes of Gossypium.

The genus Gossypium, which comprises a divergent group of diploid species and several recently formed allotetraploids, offers an excellent opportunity to study polyploid genome evolution. In this study, chromosome structural variation among the A, At, and D genomes of Gossypium was evaluated by comparative genetic linkage mapping. We constructed a fully resolved RFLP linkage map for the diploid A genome consisting of 275 loci using an F2 interspecific Gossypium arboreum x Gossypium herbaceum family. The 13 chromosomes of the A genome are represented by 12 large linkage groups in our map, reflecting an expected interchromosomal translocation between G. arboreum and G. herbaceum. The A-genome chromosomes are largely collinear with the D genomes, save for a few small inversions. Although the 2 diploid mapping parents represent the closest living relatives of the allotetraploid At-genome progenitor, 2 translocations and 7 inversions were observed between the A and At genomes. The recombination rates are similar between the 2 diploid genomes; however, the At genome shows a 93% increase in recombination relative to its diploid progenitors. Elevated recombination in the Dt genome was reported previously. These data on the At genome thus indicate that elevated recombination was a general property of allotetraploidy in cotton.

Chromosome Inversion↗

PubMed1977

The survival and transport to the site of fertilization of diploid rabbit spermatozoa.

The possible involvement of diploid spermatozoa in the production of triploid zygotes in the rabbit has been investigated in terms of the success of diploids relative to haploids in reaching the site of fertilization, with special reference to any possible selectivity of sperm transport within the female tract. The observed large significant reduction in the incidence of diploid spermatozoa between the ejaculate and the oviducts would greatly reduce the chances of, but not necessarily prevent, a diploid spermatozoon fertilizing an egg. This reduction appears to be due to a combination of the reduced survival of diploids in the female tract and a selectivity of sperm transport dependent on sperm motility.

Animals↗

PubMed2001

Maternal effect genes and the evolution of sociality in haplo-diploid organisms.

Maternal care and female-biased sex ratios are considered by many to be essential prerequisites for the evolution of eusocial behaviors among the hymenoptera. Using population genetic models, I investigate the evolution of genes that have positive maternal effects but negative, direct effects on offspring fitness. I find that, under many conditions, such genes evolve more easily in haplo-diploids than in diplo-diploids. In fact, the conditions are less restrictive than those of kin selection theory, which postulate genes with negative direct effects but positive sib-social effects. For example, the conditions permitting the evolution of maternal effect genes are not affected if females mate multiply, whereas multiple mating reduces the efficacy of kin selection by reducing genetic relatedness within colonies. Inbreeding also differentially facilitates evolution of maternal effect genes in haplo-diploids relative to diplo-diploids, although it does not differentially affect the evolution of sib-altruism genes. Furthermore, when the direct, deleterious pleiotropic effect is restricted to sons, a maternal effect gene can evolve when the beneficial maternal effect is less than half (with inbreeding, much less) of the deleterious effect on sons. For kin selection, however, the sib-social benefits must always exceed the direct costs because genetic relatedness is always less than or equal to 1.0. The results suggest that haplo-diploidy facilitates (1) the evolution of maternal care, and (2) the evolution of maternal effect genes with antagonistic pleiotropic effects on sons. The latter effect may help explain the tendency toward female-biased sex ratios in haplo-diploids, especially those with inbreeding. I conclude that haplo-diploidy not only facilitates the evolution of sister-sister altruism by kin selection but also facilitates the evolution of maternal care and female-biased sex ratios, two prerequisites for eusociality.

Alleles↗

PubMed2001

Patterns of allozyme variation in diploid and tetraploid Centaurea jacea at different spatial scales.

The extent and spatial patterns of genetic variation at allozyme markers were investigated within and between diploid and autotetraploid knapweeds (Centaurea jacea L. sensu lato, Asteraceae) at contrasted geographic scales: (1) among populations sampled from a diploid-tetraploid contact zone in the northeastern part of the Belgian Ardennes, and (2) within mixed populations from that zone where diploids and tetraploids coexist. Our data were also compared with a published dataset by Sommer (1990) describing allozyme variation in separate diploid and tetraploid knapweeds populations collected throughout Europe. Genetic diversity was higher in tetraploids. In the Belgian Ardennes and within the mixed populations, both cytotypes had similar levels of spatial genetic structure, they were genetically differentiated, and their distributions of allele frequencies were not spatially correlated. In contrast, at the European scale, diploids and tetraploids did not show differentiated gene pools and presented a strong correlation between their patterns of spatial genetic variation. Numerical simulations showed that the striking difference in patterns observed at small and large geographic scales could be accounted for by a combination of (1) isolation by distance within cytotypes; and (2) partial reproductive barriers between cytotypes and/or recurrent formation of tetraploids. We suggest that this may explain the difficulty of the taxonomic treatment of knapweeds and of polyploid complexes in general.

Asteraceae↗

PubMed2000

Centrosome amplification and instability occurs exclusively in aneuploid, but not in diploid colorectal cancer cell lines, and correlates with numerical chromosomal aberrations.

Measurement of the nuclear DNA content allows classification of human cancers as either diploid or aneuploid. To gain further insight into mechanisms of aneuploidy, we compared the cytogenetic profile of mismatch-repair-deficient diploid versus mismatch-repair-proficient aneuploid colorectal carcinoma cell lines using comparative genomic hybridization and spectral karyotyping. Aneuploid carcinomas revealed an average of 19 chromosomal imbalances per cell line. Such numerical aberrations were exceedingly scarce in the diploid tumors. This pattern of chromosomal aberrations is consistent with a mechanism involving the impairment of chromosome segregation fidelity during mitotic cell division. In support of this idea, we demonstrate the exclusive occurrence of centrosome amplification and instability in all of the aneuploid tumor cell lines analyzed. All diploid tumors contained centrosomes that were functionally and structurally indistinguishable from those in normal human fibroblasts. Due to the observed differences in centrosomes between these two classes of tumors, we incubated the cells with the microtubule depolymerizing drugs nocodazole and griseofulvin. Our results indicate that the aneuploid tumor cell lines have an increased sensitivity to these reagents and a delay in aster formation and microtubule regrowth. However, microtubule nucleation was initiated from one or two centers in both the diploid and aneuploid cells. These observations support the notion that the integrity of the centrosome plays a central role in the development of aneuploidy. Genes Chromosomes Cancer 27:183-190, 2000. Published 2000 Wiley-Liss, Inc.

Aneuploidy↗

PubMed2000

[The diploid of genetically engineered yeast for expression of hybrid HBsAg gene SA-28].

By mating a yeast haploid expressing hybrid HBsAg gene SA-28, Y19/YFD158, with another hapolid Y95, the diploid Y95xY19/YFD158 was constructed. The experiments showed that the cell density of the diploid in fermentation was three time higher than that of the haploid, the stability of expression vector in the diploid was much higher than in the haploid, the xpression level of hybrid HBsAg gene of the diploid was more than three time higher than that of the haploid and the average cope number in diploid cell was a little lower than that in the haploid.

Diploidy↗

PubMed1990

Diploids of ovicidal fungus Penicillium lanosum.

By use of auxotrophic mutants of Penicillium lanosum were prepared the heterokaryonts. From more rapidly growing sectors from heterokaryotic mycelium on minimal medium were isolated 17 diploid strains. They were prototrophic and on the whole they did not differ from the wild strain in their morphology and their growth rate. All diploids had considerably larger spores than the wild strain. Ovicidity of one half of the diploids, as well as ovicidity of the wild strain was inconspicuous and low. Ovicidity of the second half of diploids was either medium or higher, the 2nd and 3rd type. The set of these diploid mutants will serve for another study of genetic determination of ovicidity.

Animals↗

PubMed1981

Effect of culture conditions on diploid to giant-cell transformation in postimplantation mouse trophoblast.

Diploid extraembryonic ectoderm and ectoplacental cone from the 7.5-day mouse embryo were grown in vitro under a variety of culture conditions in an attempt to discover conditions which maintain trophoblast in a diploid state and prevent giant-cell formation. It was found that maintenance of tissue integrity was not enough to keep the tissues dividing and diploid, but that the presence of inner-cell-mass derivatives did have some effect. This effect was only apparent when trophoblast cells were entirely enclosed by embryonic tissues. Monolayers of embryonic or embryonal carcinoma cells did not prevent giant-cell formation. Diploid extraembryonic ectoderm and ectoplacental cone responded differently: ectoplacental cells eventually formed trophoblast giant cells even when enclosed by embryonic cells whereas extraembryonic ectoderm cells apparently could be maintained in a diploid condition. This and other differences in properties between extraembryonic ectoderm and ectoplacental cone are discussed with reference to a new model for the postimplantation trophoblast lineage in the mouse.

Animals↗

PubMed2003

The jewel wasp Nasonia: querying the genome with haplo-diploid genetics.

The jewel wasp Nasonia vitripennis is considered the "Drosophila melanogaster of the Hymenoptera." This diminutive wasp offers insect geneticists a means for applying haplo-diploid genetics to the analysis of developmental processes. As in bees, haploid males develop from unfertilized eggs, while diploid females develop from fertilized eggs. Nasonia's advantageous combination of haplo-diploid genetics and ease of handling in the laboratory facilitates screening the entire genome for recessive mutations affecting a developmental process of interest. This approach is currently directed toward understanding the evolution of embryonic pattern formation by comparing Nasonia embryogenesis to that of Drosophila. Haplo-diploid genetics also facilitates developing molecular maps and mapping polygenic traits. Moreover, Nasonia embryos are also proving amenable to cell biological analysis. These capabilities are being exploited to understand a variety of behavioral, developmental, and evolutionary processes, ranging from cytoplasmic incompatibility to the evolution of wing morphology.

Animals↗