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PubMed1985

Transmission and recombination of chloroplast genes in asexual crosses of Chlamydomonas reinhardtii. II. Comparisons with observations of sexual diploids.

Patterns of biparental chloroplast gene transmission in Chlamydomonas reinhardtii diploids produced by polyethylene glycol (PEG) fusion were found to be similar to those seen in sexual diploids (VanWinkle-Swift and Birky 1978). Examination of the phenotypes of diploid clones showed that the PEG diploids produced a heterogeneous set of allelic frequencies. Neither the frequencies of parental nor recombinant phenotypes were normally distributed. In addition, frequencies of reciprocal recombinant phenotypes showed no significant correlation in the clones from individual PEG diploids. The frequencies of parental phenotypes, on the other hand, were significantly negatively correlated. Like the data from sexual diploids, this is evidence that recombinant frequencies from clones of PEG diploids are not directly related to frequencies of reciprocal recombination. The similarity of results obtained in sexual and PEG diploids supports the hypothesis that the mechanisms operating during biparental chloroplast gene inheritance in PEG diploids are identical to those in sexual diploids.

Chlamydomonas↗

PubMed1999

Muscle growth and development in normal-sex-ratio and all-female diploid and triploid Atlantic salmon.

Muscle development and growth were investigated in diploid populations of normal-sex-ratio and all-female Atlantic salmon (Salmo salar L.) and their triploid counterparts produced by high-pressure treatment. Somites were formed at the rate of 6 h-1 in both diploids and triploids at 6 degrees C. The rostral-to-caudal development of myotubes, myofibrils and acetylcholinesterase staining at the myosepta was slightly more advanced in triploid than in diploid fish, although the differences were smaller than among individual families. The c-met receptor tyrosine kinase was used as a molecular marker for the satellite cells involved in postembryonic muscle growth. Satellite cell nuclei comprised 17.5 % of total myonuclei in smolts and they were 24 % more abundant in diploid than in triploid fish. Cells expressing the myogenic regulatory factor myf-6, a marker of satellite cells committed to differentiation, represented 14.8 % of total myonuclei in diploids and 12.5 % in triploids. At ambient temperatures, the number of white muscle fibres in normal-sex-ratio fish increased more than 30-fold between the alevin and smolt stages, and approximately 3.5-fold further during the first year of seawater growth. The rate of muscle fibre recruitment in seawater stages was significantly greater in diploid than in triploid fish, reaching 1162 fibres day-1 and 608 fibres day-1, respectively, in all-female groups 800 days post-hatching. For 42 cm fork-length fish, there were approximately one-third more muscle fibres per myotome in diploid than in triploid groups, 649 878 and 413 619, respectively, for all-female fish. The probability density function of muscle fibre diameters in each fish was estimated using non-parametric smoothing techniques, and the mean densities for diploids (fD) and triploids (fT) were calculated. The peak fibre diameter was approximately 20 (micro)m in all age classes, irrespective of ploidy. Distinct bimodal distributions of muscle fibre diameter were evident in all groups 775 days and 839 days post-hatching, reflecting seasonal cycles of fibre recruitment. fD and fT were compared using a non-parametric bootstrap technique and the reference band representing the null-hypothesis indicated that there was no difference with ploidy. Reference bands for normal-sex-ratio fish at 315 days and 470 days indicated that diploids had a higher percentage of smaller-diameter fibres and that triploid distributions had a thicker right-hand tail. Similar differences in fD and fT of muscle fibre diameters were found for all-female fish, although the statistical evidence was less strong. Reference bands indicated differences in the middle range of the distributions of muscle fibre diameter in fish 620-775 days post-hatch, with triploids having a thicker right-hand tail. Thus, a lower density of satellite cells was associated with reduced rates of fibre recruitment but a compensatory increase in muscle fibre hypertrophy in triploid compared with diploid fish.

Animals↗

PubMed2005

Characters that differ between diploid and haploid honey bee (Apis mellifera) drones.

Diploid males have long been considered a curiosity contradictory to the haplo-diploid mode of sex determination in the Hymenoptera. In Apis mellifera, 'false' diploid male larvae are eliminated by worker cannibalism immediately after hatching. A 'cannibalism substance' produced by diploid drone larvae to induce worker-assisted suicide has been hypothesized, but it has never been detected. Diploid drones are only removed some hours after hatching. Older larvae are evidently not regarded as 'false males' and instead are regularly nursed by the brood-attending worker bees. As the pheromonal cues presumably are located on the surface of newly hatched bee larvae, we extracted the cuticular secretions and analyzed their chemical composition by gas chromatograph-mass spectrometry (GC-MS) analyses. Larvae were sexed and then reared in vitro for up to three days. The GC-MS pattern that was obtained, with alkanes as the major compounds, was compared between diploid and haploid drone larvae. We also examined some physical parameters of adult drones. There was no difference between diploid and haploid males in their weight at the day of emergence. The diploid adult drones had fewer wing hooks and smaller testes. The sperm DNA content was 0.30 and 0.15 pg per nucleus, giving an exact 2:1 ratio for the gametocytes of diploid and haploid drones, respectively. Vitellogenin was found in the hemolymph of both types of imaginal drones at 5 to 6 days, with a significantly lower titer in the diploids.

Animals↗

PubMed1995

Heterogeneity of the chromatin fine structure in DNA-diploid breast cancer cells.

The chromatin fine structure of Feulgen-stained DNA-diploid tumour cells was studied by means of image cytometry in fine-needle aspiration biopsies of 115 breast cancer patients. The investigation was focused on diploid, several subtypes of polyploid, and aneuploid tumours. Only the clearly separable diploid peaks of these tumours were measured cytometrically by an OPTIMAS-based image analysis system, which led to a set of 93 primary cytometric features in each diploid subpopulation. The results demonstrate that the diploid tumours are clearly different to the diploid compartments of various subtypes of polyploid and aneuploid tumours. Between those diploid subpopulations from polyploid tumours, chromatin structure differences also exist. A higher degree of similarity between polyploid and aneuploid tumours, compared to diploid, became evident. The actual structural differences between the diploid subpopulations indicate both increasing variances within the peak and increasingly coarse and contrasted, irregular chromatin structure with the occurrence of tetraploid, octoploid, and aneuploid DNA-histogram peaks. Therefore, the structural effects of an increasing genomic instability seems not to be restricted to the non-diploid cell populations.

Adenocarcinoma↗

PubMed2026

Diploids derived from polyploids: genetic characteristics of four novel interspecific Sorghum populations.

Polyploidy has repeatedly shaped grass evolution, yet direct observations of how polyploid-derived chromosomes behave when returned to diploidy remain rare. Interspecific crosses between diploid Sorghum bicolor and tetraploid hybrids derived from Sorghum halepense generate mixed-ploidy progeny, providing an opportunity to examine chromosome transmission during the early stages of diploidization. Using genome-wide SNP markers, we characterized chromosomal inheritance patterns in 2 diploid and 2 tetraploid families derived from these crosses. Genotype-dosage profiles alone distinguished diploids from tetraploids with complete accuracy, reflecting strong ploidy-dependent differences in dosage-class distributions. Although diploid progeny retained much of the halepense-derived genomic background, several genomic intervals exhibited extended, nonrandom runs of S. bicolor homozygosity that remained polymorphic in corresponding tetraploid populations. These patterns, together with recurrent segregation distortion across independent families, suggest that the transition from tetraploidy to diploidy can expose allelic combinations that differ in transmission or viability. Analyses of flowering time further indicated that diploid and tetraploid derivatives possess distinct genomic architectures, with major association peaks occurring in different chromosomal regions across ploidy levels. Collectively, these results indicate that early diploidization involves nonrandom retention and loss of parental haplotypes shaped by both selective and structural constraints. The diploid extractions characterized here provide a rare empirical system for investigating the early stages of diploidization and a practical framework for studying and eventually mobilizing polyploid-derived variation for sorghum germplasm development. However, broader integration into elite breeding programs will require additional evaluation of cross-fertility, meiotic behavior, and chromosomal stability across diverse breeding backgrounds.

Sorghum↗

PubMed2000

Genetic alterations in DNA diploid, aneuploid and multiploid colorectal carcinomas identified by the crypt isolation technique.

Loss of heterozygosity (LOH) and microsatellite instability (MSI) commonly occur in colorectal carcinomas. However, the role of these genetic alterations in determining DNA ploidy status of tumors (diploid, aneuploid and multiploid) remains unclear. In the present study, we attempted to clarify the relationship between genetic alterations and DNA ploidy status. Crypt isolation coupled with DNA cytometric sorting and polymerase chain reaction assay (17 microsatellite markers) were used to study allelic losses and MSI in 59 colorectal carcinomas (diploid, 15; aneuploid, 10 and multiploid, 34). Of the 15 diploid carcinomas, 6 exhibited MSI in which allelic losses were rarely found. The other 9 diploid tumors mostly exhibited allelic losses, but none displayed MSI status. Whereas allelic losses frequently occurred in the aneuploid carcinomas and the aneuploid populations of multiploid carcinomas, they were rarely detected in the diploid populations of multiploid carcinomas. MSI status was not observed in aneuploid carcinomas nor in either population of multiploid carcinomas. Although multiploid carcinomas genetically resemble aneuploid carcinomas in the expression of the severe LOH phenotype, the genetic alterations seen in the diploid populations of multiploid carcinomas may differ from those of diploid carcinomas. Furthermore, all diploid, aneuploid and both the diploid and aneuploid fractions of the multiploid tumors that were non-MSI exhibited a high rate of LOH, suggesting that LOH is independent of the tumor's ploidy status.

Adenocarcinoma↗

PubMed2001

Comparison of the gonadal development and plasma levels of sex steroid hormones in diploid and triploid sea bass, Dicentrarchus labrax L.

The goal of this study was to compare the reproductive physiology of triploid and diploid European sea bass (Dicentrarchus labrax L.). Gonads of diploid and triploid fish (males and females) were examined both microscopically and macroscopically, together with the plasma levels of the major sex steroids produced (testosterone and estradiol-17beta) when fish were adults. Prior to sexual maturation, the gonadosomatic index (GSI) of triploid males was similar to that of diploids. However, the GSI in 4-year-old adult triploid males was 1.8 times lower than that of diploids (P < 0.05). All diploid males exhibited normal gonadal development. In contrast, in triploid males spermatogenesis was impaired during late meiosis, affecting severely spermiogenesis. This was achieved by an increasing imbalance in the amount of DNA present in daughter cells of the same type as spermatogenesis progressed, as demonstrated by abnormal cell sizes, culminating in inviable spermatids. Thus, no spermiating triploid fish were observed during 4 years, which included three full consecutive maturation cycles. Furthermore, the germ cells from triploids were significantly larger than those from diploids (P < 0.001). Seasonal profiles of plasma levels of testosterone in 4-year-old males were essentially similar in both ploidies. On the other hand, triploid females had rudimentary ovaries containing oogonia and primary oocytes that were arrested during meiotic prophase I, while diploid females exhibited all stages of ovarian development. Diploid females showed levels of testosterone and estradiol-17beta significantly higher than those of triploids (P < 0.05), in which no endocrine signs of maturation were observed at all. Regarding sex ratios, triploids had 10% more females than diploids (P < 0.05) but in both ploidies males predominated, as is usually found in this species under culture conditions. These results show that triploidy blocked the initial phases of meiosis in females and the latter ones in males, resulting in the absence of or reduced gonadal development, respectively. In conclusion, we provide an explanation for the lack of gonadal development in triploid male fish, and, to the best of our knowledge, we report for the first time a case in which induced triploidy completely blocks meiosis in both sexes, thus conferring functional sterility in the sea bass.

Animals↗

PubMed1992

Direct induction of tetraploids or homozygous diploids in the industrial yeast Saccharomyces cerevisiae by hydrostatic pressure.

Hydrostatic pressure and a dye plate method were used to investigate the direct induction of tetraploids or homozygous diploids from the industrial diploid or haploid yeast Saccharomyces cerevisiae. Above 200 MPa, hydrostatic pressure greatly inactivated the strains HF399s1 (alpha haploid), P-540 (a/alpha diploid), and P-544 (a/alpha diploid). At the same time, when pressure-treated cells of these strains were spread on a dye plate, some of the visible colonies were stained red/blue or dark blue (variant colonies); the rest stained violet, similar to colonies originating from diploid cells or haploid cells that were not pressure-treated. In addition, above 100 MPa, the formation of variant colonies increased with increasing pressure, and maximized (1 x 10(-1)) at 200 and 250 MPa, respectively. The size of almost all variant cells from P-544, P-540, and HF399s1 was visibly increased compared with that of untreated cells and the measured cellular DNA content of P-540 and HF399s1 was double that of untreated cells. Furthermore, based on random spore analysis and mass-matings, induced variants in the diploid strains were found to be tetraploid with an a/a/alpha/alpha genotype at the mating-type locus or, in the haploid strains, homozygous diploid with an alpha/alpha genotype. From these results we conclude that pressure treatment in combination with a dye plate is a useful method for strain improvement by direct induction of tetraploids or homozygous diploids from industrial strains whether diploid or haploid.

Crosses, Genetic↗

PubMed2003

Stage-specific effects of the osmolarity of a culture medium on the development of parthenogenetic diploids in the pig.

The objective of this study was to investigate the effects of osmolarity of culture media on the development of porcine parthenogenetic diploids. Oocyte-cumulus-granulosa cell complexes were collected from ovaries and then in vitro-cultured for 48 h. The mature oocytes were subjected to a single electro-stimulation (El-St; 100 micros, 1500 V/cm), treated with 5.0 microg/ml Cytochalasin B for 4h and then cultured under various conditions as described below. In Experiment 1, the diploids were cultured for 168 h after El-St in modified Whitten's medium with 256 mOsmol (mWM256), mKRB with 309 mOsmol, and mWM with 309 mOsmol (mWM309), in which the osmolarity was adjusted by addition of NaCl or mannitol, or by reduction of distilled water. In Experiment 2, the diploids were cultured in the five media used in Experiment 1 for the first 48 h, and then in mWM256 until 168 h after El-St. In Experiment 3, the diploids were cultured for the first 48 h in mWM with osmolarity adjusted from 256 to 330 mOsmol by addition of NaCl for the first 48 h and then in mWM256 until 168 h after El-St. In Experiment 4, the diploids were cultured in mWM with 290 mOsmol (mWM290) for the first period of 24, 48, or 72 h, and then in mWM256 until 168 h after El-St. In Experiment 5, after diploids were cultured in mWM290 for the first 48 h, the obtained 4-cell diploids were transferred to mWM with osmolarity adjusted from 200 to 310 mOsmol by addition of NaCl, then cultured until 168 h after El-St. All media were supplemented with 0.5mg/ml hyaluronic acid and 4.0mg/ml bovine serum albumin. The results obtained in Experiments 1-5 indicate that the osmolarity of a medium, but not the Na(+)/K(+) ratio, exerts effects on the development of diploids to the blastocyst stage. The change of osmolarity of the culture media after the 4-cell stage increased the rate of expanded blastocyst formation in porcine diploids. The optimal osmolarities of culture medium for the first 48 h after El-St (before the 4-cell stage) were 290 and 280-320 mOsmol, and those for the later period (after the 4-cell stage) were 256 and 220-270 mOsmol, respectively.

Animals↗

PubMed2002

Characteristics of preimplantational development of porcine parthenogenetic diploids relative to the existence of amino acids in vitro.

The present study was designed to investigate the effects of amino acids on the in vitro development of porcine parthenogenetic diploids that were produced by electrostimulation (El-St) and cytochalasin B treatment of in vitro-matured oocytes. The culture medium for development, based on Whitten medium, contained 0.5 mg/ml of hyaluronic acid (mWM), and a two-step culture system in which 290 mOsmol before the 4-cell stage (48 or 72 h after El-St) and, subsequently, 256 mOsmol up to the blastocyst stage (mWMs) were used. In experiment 1, the diploids were cultured for 168 h in mWMs supplemented with 0.01-5 mg/ml of polyvinyl alcohol (PVA). In experiment 2, the diploids were cultured in mWMs containing 0.5 mg/ml of PVA (PVA-mWMs) for 0, 48, or 72 h and then cultured for 168 h after El-St in PVA-mWMs supplemented with essential amino acids for Eagle basal medium without glutamine (E-AA) and nonessential amino acids for minimum essential medium (NE-AA). The results showed that diploids can develop up to the blastocyst stage in mWMs including 0.05-5.0 mg/ml of PVA (49%-53% vs. 63%, P > 0.05), but the replacement of BSA with PVA alone could not support the expansion of blastocysts (11%-20% vs. 39%, P < 0.05) or their proliferation. The addition of both E-AA and NE-AA (E+NE-AA) to PVA-mWMs from the 1-cell stage resulted in severe inhibition of the development of diploids to the blastocyst stage. However, the addition of E+NE-AA to PVA-mWMs later than 48 or 72 h after El-St well supported the development of diploids to the blastocyst stage and supported the expansion of blastocysts. In experiments 3-5, which types of amino acids in E-AA inhibited the development of diploids during the first 48 h after El-St were determined. In experiment 6, the stimulatory effects of E-AA and/or NE-AA after the 4-cell stage were examined. The results of those experiments clearly showed that the presence of nonpolar E-AA, especially for valine, leucine, isoleucine, and methionine, during the first 48 h after El-St caused severe delay of the first division and inhibition of development beyond the 4-cell stage. The presence of NE-AA after the 4-cell stage produced a favorable condition for the expansion of blastocysts (33%), whereas the presence of E-AA increased the cleavage rates of the diploids after compaction and the total number of cells in the blastocysts (53.7 +/- 2.7) and inner cell mass (12 +/- 0.5). These findings indicate that the presence of nonpolar E-AA in a protein-free medium during the first 48 h causes the 4-cell block in porcine parthenogenetic diploids.

Amino Acids↗

PubMed2000

Fitness differences among diploids, tetraploids, and their triploid progeny in Chamerion angustifolium: mechanisms of inviability and implications for polyploid evolution.

Theoretical models indicate that the evolution of tetraploids in diploid populations will depend on both the relative fitness of the tetraploid and that of the diploid-tetraploid hybrids. Hybrids are believed to have lower fitness due to imbalances in either the ploidy (endosperm imbalance) or the ratio of maternal to paternal genomes in their endosperm (genomic imprinting). In this study we created diploids, tetraploids, and hybrid triploids of Chamerion angustifolium from crosses between field-collected diploid and tetraploid plants and evaluated them at six life stages in a greenhouse comparison. Diploid offspring (from 2x x 2x crosses) had significantly higher seed production and lower biomass than tetraploid offspring (from 4x x 4x crosses). Relative to the diploid, the cumulative fitness of tetraploids was 0.67. In general, triploids (from 2x x 4x, 4x x 2x crosses) had significantly lower seed production, lower pollen viability, and higher biomass than diploid individuals. Triploid offspring derived from diploid maternal parents had lower germination rates, but higher pollen production than those with tetraploid mothers. Relative to diploids, the cumulative fitness of 2x x 4x triploids and 4x x 2x triploids was 0.12 and 0.06, respectively, providing some support for effect of differing maternal:paternal ratios and endosperm development as a mechanism of hybrid inviability. Collectively, the data show that tetraploids exhibit an inherent fitness disadvantage, although the partial viability and fertility of triploids may help to reduce the barrier to tetraploid establishment in sympatric populations.

Biological Evolution↗

PubMed1987

Industrial Application of Artificially Induced Diploid Strains of Torulaspora delbrueckii.

Diploid strains of Torulaspora delbrueckii were tested for industrial application. Because the cell volume of the diploid strain was three times as large as that of the parental haploid strain, collection and subsequent dehydration to make compressed yeast cakes were greatly improved with the diploid YL3. The time required for dehydration of the diploid strain was shortened to 1/2.5 that of the parent strain under conventional conditions. Moreover, for the diploid cells frequent filter changes for dehydration were not required, which was the case with parental cells. Fermentation activity and tolerance to freeze-thawing in dough were succesfully inherited by the diploid strains. The diploid YL3 showed nearly the same activity as the diploid F31 in bread making. However, the endurance period of yeast cakes when stored at 30 degrees C without softening to lead to liquefaction was much longer in YL3 (199 h) than in F31 (132 h). This superiority was ascribed to the fact that YL3 was induced through direct diploidization and had no genetic defect on chromosomes because the wild-type strain was employed as the parent, whereas F31 was obtained through protoplast fusion from two auxotrophic mutants and carried at least two mutagenized genes that were masked by heterolallelism.

Journal Article↗

PubMed1992

Biotransformation in carcinogen-induced diploid and polyploid hepatocytes separated by centrifugal elutriation.

Biotransformation in carcinogen-induced diploid and polyploid hepatocytes was studied using isozyme-selective substrates for several enzyme pathways. Diploid hepatocytes were induced by partial hepatectomy, a single injection of diethylnitrosamine, and 4 weeks of 2-acetylaminofluorene (2-AAF) feeding. Then, after an additional 3-5 weeks on the control diet, diploid and polyploid hepatocytes were separated from freshly isolated hepatocytes by centrifugal elutriation. Benzo(a)pyrene hydroxylase, ethoxyresorufin O-deethylase, and methoxycoumarin O-demethylase activities were approximately 15-40% lower in the diploid hepatocyte fraction than in the polyploid cell fraction. Activities of 1-chloro-2,4-dinitrobenzene, glutathione S-transferase, 3-hydroxy-benzo(a)pyrene or 4-hydroxybiphenyl UDP-glucuronosyltransferase, and DT-diaphorase were not different in the two cell fractions. Determination of activity during the 2-AAF treatment indicated that 2-AAF increased 7-ethoxyresorufin O-deethylase and 3-hydroxybenzo(a)pyrene glucuronosyltransferase activities by 300 and 200%, respectively, in both the diploid and polyploid hepatocyte fractions. Administration of phenobarbital for 4 days at the end of the control diet period increased ethoxyresorufin and methoxycoumarin dealkylations by 2- and 4-fold, and 3-hydroxybenzo(a)pyrene glucuronidation and 1-chloro-2,4-dinitrobenzene conjugation with glutathione by 1.5- to 2-fold in both hepatocyte fractions. Slight increases in benzo(a)pyrene hydroxylation and 4-hydroxybiphenyl glucuronidation were also evident in diploid cells. Although there is a slight decrease in cytochrome P-450-dependent monooxygenase activities, these data indicate that carcinogen-induced diploid hepatocytes do not show the typical toxicant-resistant phenotype observed in preneoplastic hepatocytes of altered liver foci, which are characterized by large decreases in monooxygenase biotransformations as well as increased activities of several phase II enzymes. This finding is compatible with the hypothesis that 2-AAF-induced nonploidizing growth of diploid hepatocytes is caused by nontoxic mechanisms in the present experimental paradigm. In addition, carcinogen-induced diploid cells respond to phenobarbital in a manner similar to that of polyploid hepatocytes.

2-Acetylaminofluorene↗

PubMedDate not supplied

[Relative competitiveness of haploid and diploid yeast cells growing in a mixed population].

Saccharomyces cerevisiae was grown in a rich medium under the conditions of "quasi-continuous" cultivation and, after 200-300 generations, its diploid cells almost completely displaced haploid cells from the original mixed "haploid-diploid" population where the ratio between diploid and haploid strains was either 1:1 or 1:100. The cultivation at 40 degrees C did not change the relative competitive ability of haploids and diploids. When cells were cultivated in a rich medium at 6 degrees C or in a minimal medium at 30 degrees C, none of the strains showed an advantage over others for about 200 generations. Haploid cells had an advantage over diploid cells during "quasi-continuous" growth in the minimal medium at 30 degrees C. When the temperature was elevated to 40 degrees C, diploid cells displaced haploid cells from the mixed population. No advantage was found for diploid or haploid cells grown in a medium with an elevated KCl content (1.5 M). Haploid cells had an advantage over diploid cells when Pichia pinus was cultivated in a minimal medium. The results are discussed using the hypothesis about the diploid phase being fixed in the course of biological evolution.

Diploidy↗

PubMed1995

[Evolution of aneuploidy from diploid colorectal carcinoma as revealed by the analyses of ploidy heterogeneity and Ras mutation patterns].

UNLABELLED: To analyze ploidy alterations during progression of colorectal tumors, we mapped the ploidy constitutions by cytofluorometry using (measurements of metaphase cells in) tissue sections as well as cell suspensions isolated from the tissue sections. Clonality of the tumor with heterogeneous ploidy constitution was checked by mutation pattern of K-ras codon 12. To assess the significance of polyploidy detected in the diploid tumor component, the present materials were confined to 23 tumors that contained diploid tumor cells. RESULTS: 1) Eight diploid tumors without polyploidy that invaded the submucosa or deeper were greater than 2 cm in diameter. 2) Aneuploidy was detected in tissue sections from 9 out of 15 tumors that had diploid component with polyploidy, and was occasionally predominant in the extramucosal invasive parts. 3) Near-diploid aneuploidy was detected in the cells isolated from diploid (+ polyploid) regions of 2 tumors with aneuploidy. 4) Three of the 6 tumors with heterogeneous ploidy constituents had ras mutation with the mutation patterns common to diploid and aneuploid parts. These findings suggest that aneuploid cells evolve preferentially from the diploid tumor cell population with polyploidy, which often include near-diploid aneuploidy.

Aneuploidy↗

PubMed1975

[Effect of uvs1, uvs2 and xrs mutations on the radiosensitivity of and frequency of induced mitotic recombination in diploid yeast cells].

Effect of radiosensitivity mutations uvs1, uvs2 and xrs in homozygous state in yeast Saccharomyces cerevisiae on UV and X-ray sensitivity and on the induced mitotic recombination is studied. Diploids uvs2 uvs2 xrs xrs are much more UV-sensible than diploids UVS2 UVS2 xrs xrs or UVS2 uvs2 xrs xrs. Diploids uvs1 uvs1 uvs2 uvs2 and uvs1 uvs1 UVS2 UVS2 have the same radiosensitivity. These data show that mutations uvs1, uvs2 and xrs block different ways of the elimination of UV-induced damages. The diploid uvs2 uvs2 xrs3 xrs3 is much more X-ray sensible, than the diploid UVS2 UVS2 xrs3 xrs3. It shows that mutations uvs2 and xrs3 block different ways of the elimination of X-ray induced damages. All double mutant diploids are characterized by a higher frequency of UV-induced mitotic recombination, than the diploid UVS UVS XRS XRS and the UV-sensitive diploid uvs2 uvs2 XRS XRS. The diploid uvs2 uvs2 xrs5 xrs5 is characterized by an extraordinary high frequency of X-RAY INDUCED MITOTIC RECOMBINATION.

Crossing Over, Genetic↗

PubMed2007

Diploid sperm produced by artificially sex-reversed clone loaches.

Clone loaches reproduce unisexually in a wild population of Hokkaido Island, Japan. These clone loaches produce genetically identical unreduced eggs which develop to diploid individuals without any genetic contribution of sperm donors. In the present study, sex reversal of clone loaches was attempted and the reproductive potential of resultant clone males was examined. Clone loaches administered 0.5 ppm of 17-alpha methyltestosterone (MT) for 30 days from 1 month after hatching differentiated into physiological males. These sex-reversed clone males produced fertile spermatozoa with a diploid DNA content. Diploid spermatozoa had significantly larger heads than normal haploid sperm, but had a normal shape showing a head, mid-piece, and tail. The motility of diploid spermatozoa was low after ambient water was added. Concentration of diploid spermatozoa per unit of sperm was lower than that of control haploid spermatozoa. Microsatellite genotyping revealed that triploid progeny from the cross between a normal diploid female and a sex-reversed clone male had two alleles specific to the diploid clone male and one allele of the mother loach. These results indicated that the sex-reversed clone males produced fertile diploid spermatozoa genetically identical to the clone lineage.

Animals↗

PubMed1993

Carcinogen-induced diploid hepatocytes: sensitive target cells for transformation by mutated c-Ha-ras oncogene.

Sequential treatment of partially (two-thirds) hepatectomized rats with diethylnitrosamine and 2-acetylaminofluorene induces the emergence of diploid hepatocytes in rat liver. These carcinogen-induced diploid cell populations are thought to contain the progenitors of hepatocellular carcinoma (HCC), i.e., initiated, cells. In the study presented here, we addressed the question of whether putative mutations in carcinogen-induced diploid hepatocytes can cooperate with activated oncogenes in the process of transformation in vitro. Both carcinogenesis in vivo and transformation in vitro have been shown to be multistep processes requiring at least two independent transforming events. Diploid and polyploid rat hepatocytes were isolated by centrifugal elutriation. The purity of the elutriated fractions was 88 +/- 3% in the diploid fraction and 84 +/- 3% in the polyploid fraction. Hepatocytes from both the elutriated cell fractions and, for comparison, hepatocytes from untreated rats were transfected by electroporation with oncogene expression vectors containing the mutated human T24 c-Ha-ras gene and of the N-myc gene. Transient expression of transfected DNA was similar in both hepatocyte populations. No cell lines could be established by using the N-myc vector. In contrast, the carcinogen-induced diploid hepatocytes, but not polyploid hepatocytes, could be converted by transfection with the ras vector into permanent anchorage-independent growing cell lines with hepatocyte-like morphology and differentiation. These cell lines expressed the myc proto-oncogene and transforming growth factor-alpha constitutively. Thus, carcinogen-induced diploid hepatocytes are sensitive to transformation by the ras oncogene, suggesting cooperation between putative preexisting mutations in the diploid cells and the ras oncogene product in hepatocellular transformation.

2-Acetylaminofluorene↗