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PubMed2006

An alternative method of deriving embryonic stem cell-like clones by aggregation of diploid cells with tetraploid embryos.

OBJECTIVE: To assess whether embryonic stem (ES) cells could be derived from the aggregation of diploid cells with tetraploid embryos. DESIGN: Randomized, prospective study. SETTING: University embryology and gamete biotechnology laboratory. ANIMAL(S): F1 (C57BL6/DBA2) mice. INTERVENTION(S): Four- to eight-cell F1 tetraploid embryos were aggregated with 10 to 15 donor E14 ES cells. MAIN OUTCOME MEASURE(S): Embryogenesis and ES cell establishment. RESULT(S): No difference (78% to 89%) in blastocyst formation was detected between the aggregated tetraploid and the control diploid embryos. In a total of 27 transfers, pregnancy was detected in three tetraploid (23.1%) and five diploid (35.7%) cases, and three live births developed from the aggregated tetraploid embryos. The tetraploid blastocysts without aggregation were plated, but no ES cell-like colony was formed. Six of eight aggregated blastocysts derived well-proliferated colonies, which were positive for anti-stage-specific embryonic antigen (SSEA)-1 antibody, Oct-4, and alkaline phosphatase. The microsatellite assay confirmed the homogenous makeup among the donor E14 cells and live-birth and ES-like cells derived from the E14-aggregated, tetraploid embryo. CONCLUSION(S): The aggregation of pluripotent diploid cells with tetraploid embryos yielded live births and ES-like cells that were homogenous to the donor diploid cells.

Animals↗
PubMed2006

Systematic factor optimization for sperm cryopreservation of tetraploid Pacific oysters, Crassostrea gigas.

The availability of tetraploid Pacific oysters provides a unique opportunity for comparative studies of sperm cryopreservation between diploids and tetraploids. In parallel to studies with sperm from diploid oysters, this study reports systematic factor optimization for sperm cryopreservation of tetraploid oysters. Specifically, this study evaluated the effects of cooling rate, single or combined cryoprotectants at various concentrations, equilibration time (exposure to cryoprotectant), and straw size. Similar to sperm from diploids, the optimal cooling rate was 5 degrees C/min to -30 degrees C, followed by cooling at 45 degrees C/min to -80 degrees C before plunging into liquid nitrogen. Screening of single or combined cryoprotectants at various concentrations showed that a combination of the cryoprotectants 6% polyethylene glycol/4% propylene glycol and 6% polyethylene glycol/4% dimethyl sulfoxide yielded consistently high post-thaw motility. A long equilibration (60 min) yielded higher percent fertilization, and confirmed that extended equilibration could be beneficial when low concentrations of cryoprotectant are used. There was no significant difference in post-thaw motility between straw sizes of 0.25 and 0.5 mL. Despite low post-thaw fertilization (<10%) in general for sperm from tetraploids, optimized protocols in the present study effectively retained post-thaw motility for sperm from tetraploid oysters. This study confirmed that sperm from tetraploid Pacific oysters were more negatively affected by cryopreservation than were those of diploids. One possible explanation is that sperm from these two ploidies are different in their plasma membrane properties (e.g., structure, permeability, and elasticity), and the plasma membrane of sperm from tetraploids is more sensitive to cryopreservation effects. The fact that combinations of non-permeating and permeating cryoprotectants improved post-thaw motility in sperm from tetraploids provided presumptive evidence for this interpretation.

Animals↗
PubMed1999

Seasonal variations of Artemisinin and its biosynthetic precursors in tetraploid Artemisia annua plants compared with the diploid wild-type.

Using colchicine we induced tetraploidy in Artemisia annua L. plants. During a vegetation period we monitored the time course of the levels of artemisinin, its direct precursors, the biosynthetically related sesquiterpenes and the essential oil content in the diploid (wild-type) and tetraploid A. annua plants. The averaged artemisinin level in tetraploids was 38% higher than that of the wild-type as measured over the whole vegetation period. In contrast, the averaged essential oil content of the tetraploids over this period was 32% lower. This might suggest a reciprocal correlation between artemisinin (sesquiterpenes) and the essential oil content (monoterpenes). The averaged biomass of the leaves of the tetraploid plants was lower compared to the wild-type plants. Therefore, the artemisinin yield per m2 tetraploids was decreased by 25%. Although the tetraploid plants were smaller than the wild-type plants, certain individual organs like the leaves were considerably larger, and seeds obtained by cross pollination between tetraploid A. annua plants had a spectacular size. In principle, tetraploid A. annua can be a useful starting material for a breeding program in order to obtain larger and faster growing plants, which produce higher levels of artemisinin.

Artemisinins↗
PubMed2001

Hybrid vigor, fetal overgrowth, and viability of mice derived by nuclear cloning and tetraploid embryo complementation.

To assess whether heterozygosity of the donor cell genome was a general parameter crucial for long-term survival of cloned animals, we tested the ability of embryonic stem (ES) cells with either an inbred or F(1) genetic background to generate cloned mice by nuclear transfer. Most clones derived from five F(1) ES cell lines survived to adulthood. In contrast, clones from three inbred ES cell lines invariably died shortly after birth due to respiratory failure. Comparison of mice derived from nuclear cloning, in which a complete blastocyst is derived from a single ES cell, and tetraploid blastocyst complementation, in which only the inner cell mass is formed from a few injected ES cells, allows us to determine which phenotypes depend on the technique or on the characteristics of the ES cell line. Neonatal lethality also has been reported in mice entirely derived from inbred ES cells that had been injected into tetraploid blastocysts (ES cell-tetraploids). Like inbred clones, ES cell-tetraploid pups derived from inbred ES cell lines died shortly after delivery with signs of respiratory distress. In contrast, most ES cell-tetraploid neonates, derived from six F(1) ES cell lines, developed into fertile adults. Cloned pups obtained from both inbred and F(1) ES cell nuclei frequently displayed increased placental and birth weights whereas ES cell-tetraploid pups were of normal weight. The potency of F(1) ES cells to generate live, fertile adults was not lost after either long-term in vitro culture or serial gene targeting events. We conclude that genetic heterozygosity is a crucial parameter for postnatal survival of mice that are entirely derived from ES cells by either nuclear cloning or tetraploid embryo complementation. In addition, our results demonstrate that tetraploid embryo complementation using F(1) ES cells represents a simple, efficient procedure for deriving animals with complex genetic alterations without the need for a chimeric intermediate.

Animals↗
PubMed2002

Pollen competition as a unilateral reproductive barrier between sympatric diploid and tetraploid Chamerion angustifolium.

Speciation requires the evolution of barriers to gene exchange between descendant and progenitor populations. Cryptic reproductive barriers in plants arise after pollination but before fertilization as a result of pollen competition and interactions between male gametophytes and female reproductive tissues. We tested for such gametic isolation between the polyploid Chamerion angustifolium and its diploid progenitor by conducting single (diploid or tetraploid) and mixed ploidy (1 : 1 diploid and tetraploid) pollinations on both cytotypes and inferring siring success from paternity analysis and pollen-tube counts. In mixed pollinations, polyploids sired most (79%) of their own seeds as well as those of diploids (61%) (correcting for triploid block, siring success was 70% and 83%, respectively). In single donor pollinations, pollen tubes from tetraploids were more numerous than those from diploids at four different positions in each style and for both diploid and tetraploid pollen recipients. The lack of a pollen donor x recipient interaction indicates that the tetraploid siring advantage is a result of pollen competition rather than pollen-pistil interactions. Such unilateral pollen precedence results in an asymmetrical pattern of isolation, with tetraploids experiencing less gene flow than diploids. It also enhances tetraploid establishment in sympatric populations, by maximizing tetraploid success and simultaneously diminishing that of diploids through the production of inviable triploid offspring.

Crosses, Genetic↗
PubMed1995

Tetraploids of the lung fluke Paragonimus westermani found in China.

Two groups of Paragonimus westermani (Tematoda: Platyhelminthes) exist in nature: diploids and triploids. Generally, these two groups live allopatrically, but in Kuandian, Liaoning Province, in the Republic of China, they live sympatrically. In our Chinese experiment on Paragonimus we used metacercariae of P. westermani, which we collected in Kuandian, Xigutai, and performed a cytological analysis. The results were as follows: (1) the P. westermani in Xigutai lived sympatrically as diploids and triploids; (2) all of the small metacercariae were diploids; (3) the large metacercariae were in large proportion triploids; (4) we found one tetraploid specimen in both the medium and the large metacercariae--this was the first time tetraploid lung flukes were discovered; (5) the somatic chromosomes of the tetraploids were different in numbers (4n = 44), but we could not find any difference in the karyotype of haploid sets and that of the diploids and the triploids; (6) unlike the triploids, during their meiosis the tetraploids produced a chromosome pairing, and we found a tendency of the large chromosomes to become quadrivalent; and (7) also unlike the triploids, a great number of spermatids were found in the tetraploid testes. Because of these findings, we can consider tetraploids to be autotetraploids, and these are probably produced by the fertilization of diploids and triploids. We also think that the gametes of tetraploids have a fertilization capability.

Animals↗
PubMed2002

Studies on the origin and evolution of tetraploid wheats based on the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA.

In this study, the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA in the tetraploid wheats, Triticum turgidum (AABB) and Triticum timopheevii (AAGG), their possible diploid donors, i.e., Triticum monococcum (AA), Triticum urartu (AA), and five species in Aegilops sect. Sitopsis (SS genome), and a related species Aegilops tauschii were cloned and sequenced. ITS1 and ITS2 regions of 24 clones from the above species were compared. Phylogenetic analysis demonstrated that Aegilops speltoides was distinct from other species in Aegilops sect. Sitopsis and was the most-likely donor of the B and G genomes to tetraploid wheats. Two types of ITS repeats were cloned from Triticum turgidum ssp. dicoccoides, one markedly similar to that from T. monococcum ssp. boeoticum (AA), and the other to that from Ae. speltoides (SS). The former might have resulted from a recent integression event. The results also indicated that T. turgidum and T. timopheevii might have simultaneously originated from a common ancestral tetraploid species or be derived from two hybridization events but within a very short interval time. ITS paralogues in tetraploid wheats have not been uniformly homogenized by concerted evolution, and high heterogeneity has been found among repeats within individuals of tetraploid wheats. In some tetraploid wheats, the observed heterogeneity originated from the same genome (B or G). Three kinds of ITS repeats from the G genome of an individual of T. timopheevii ssp. araraticum were more divergent than that from inter-specific taxa. This study also demonstrated that hybridization and polyploidization might accelerate the evolution rate of ITS repeats in tetraploid wheats.

Journal Article↗
PubMed2006

Apoptosis regulation in tetraploid cancer cells.

Tetraploidy can result in cancer-associated aneuploidy. As shown here, freshly generated tetraploid cells arising due to mitotic slippage or failed cytokinesis are prone to undergo Bax-dependent mitochondrial membrane permeabilization and subsequent apoptosis. Knockout of Bax or overexpression of Bcl-2 facilitated the survival of tetraploid cells at least as efficiently as the p53 or p21 knockout. When tetraploid cells were derived from diploid p53 and Bax-proficient precursors, such cells exhibited an enhanced transcription of p53 target genes. Tetraploid cells exhibited an enhanced rate of spontaneous apoptosis that could be suppressed by inhibition of p53 or by knockdown of proapoptotic p53 target genes such as BBC3/Puma, GADD45A and ferredoxin reductase. Unexpectedly, tetraploid cells were more resistant to DNA damaging agents (cisplatin, oxaliplatin and camptothecin) than their diploid counterparts, and this difference disappeared upon inhibition of p53 or knockdown of p53-inducible ribonucleotide reductase. Tetraploid cells were also more resistant against UVC and gamma-irradiation. These data indicate the existence of p53-dependent alterations in apoptosis regulation in tetraploid cells.

Animals↗
PubMed2005

To succeed globally, disperse locally: effects of local pollen and seed dispersal on tetraploid establishment.

Newly formed tetraploid plants in sympatry with their diploid progenitors should face significant obstacles to persistence and population establishment because of low-fitness triploids formed by cross-ploidy pollinations. Prior models have found restrictive conditions for a minority tetraploid subpopulation to persist. A stochastic spatial model, parameterized using snow buttercups (Ranunculus adoneus), was used to examine the influence of limited seed and pollen dispersal distances on the success of minority tetraploids and the interaction of these factors with different rates of self-pollination and tetraploid advantage. Higher rates of self-pollination and increased tetraploid advantage increase the probability of tetraploid persistence. Limiting the dispersal of seeds and pollen further increases the positive impact of any given level of self-pollination and tetraploid advantage. Taxa with short-distance seed and pollen dispersal should face much less stringent barriers to sympatric polyploid speciation than taxa with long-distance dispersal patterns. With short-distance seed and pollen dispersal, polyploid speciation should be possible in the absence of ecological differentiation or recurrent polyploid formation through unreduced gametes.

Crosses, Genetic↗
PubMed1957

Microspectrophotometry of cell nuclei stained with the Feulgen reaction. IV. Formation of tetraploid nuclei in rat liver cells during postnatal growth.

1. DNA contents of the individual parenchymal nuclei of rat livers during postnatal growth were estimated by microspectrophotometric apparatus, and different ploidy classes of nuclei were classified by their DNA contents. With the same material the total number of parenchymal nuclei in the liver was counted microscopically. 2. If the DNA content of nuclei encountered most frequently in several tissues represents the diploid class, the ploidy classes of the rat liver cell nuclei correspond to di-, tri-, tetra-, and octoploid, with the di- and tetraploid ones predominating considerably. 3. In suckling rats (below 25 gm. of body weight) the liver parenchyma is composed almost exclusively of cells with diploid nuclei, whereas in young rats (above 80 gm.), of tetraploid nuclei. In the growth stage between 25 and 80 gm., there is a remarkable replacement of the diploid nuclei by the tetraploid ones. However, in the liver of adult rats weighing more than 150 gm., any increase or decrease in the frequency of diploid and tetraploid nuclei is hardly observable. In such rats, the nuclear population of the liver parenchyma seems to reach a cell-ecological equilibrium which is considered to be a stable one. 4. It is shown that such nuclear populations and the total number of nuclei in a liver are controlled by the growth state, and not by the age. 5. The decrease in the total number of diploid nuclei and the increase in tetraploid nuclei in the growing livers of rats weighing from 40 up to 130 gm. can both be explained by the hypothesis that the tetraploid nuclei originate from the interphase diploid nuclei without involving mitosis. This hypothesis implies that mitosis is confined to the reproduction of diploid cells alone. 6. It is suggested that, in general, the synthesis of DNA does not necessarily result in the formation of visible mitotic chromosomes. 7. Mitotic time and generation time of diploid nuclei and the percentage of the tetraploidization from diploid nuclei are calculated and discussed.

Animals↗
PubMedDate not supplied

Clinicopathological and biological features of DNA tetraploid colorectal cancers.

PURPOSE: Most studies of colorectal cancers focus on a comparison of DNA diploid to non-diploid tumors consisting of tetraploid and aneuploid tumors. Tetraploid tumors alone have not been well studied. In the present study, clinicopathological and biological features of tetraploid colorectal cancers in contrast to those of diploid and aneuploid ones were investigated. PATIENTS AND METHODS: DNA ploidy in 278 primary colorectal adenocarcinomas was determined by flow cytometry. RESULTS: Among 278 cases, 8% of the cases were tetraploidy, 44% were aneuploidy, and 48% were diploidy. Compared to diploid tumors, tetraploid tumors were more frequent in advanced stage, high index of S-phase fraction and apoptosis, higher expression of Cox-2, c-erbB-2 and heat shock protein, but had decreased inflammatory infiltration (P<0.05). Compared to aneuploid tumors, tetraploid tumors had a high frequency of microsatellite instability, high expression of Cox-2 and heat shock protein (P<0.05). Unlike tetraploid tumors, aneuploid tumors had increased p53 expression but did not have microsatellite instability (P<0.05). Tetraploidy and aneploidy predicted a worse prognosis in the subgroups of stages A-C, proximal colon, p53 negative expression and higher S-phase fraction (P<0.05). CONCLUSIONS: DNA tetraploid tumors seem, to some extent, to exhibit distinct characteristics of clinicopathology and biology compared with aneuploid or diploid colorectal cancers.

Colorectal Neoplasms↗
PubMed2003

Tetraploid development in the mouse.

Spontaneous duplication of the mammalian genome occurs in approximately 1% of fertilizations. Although one or more whole genome duplications are believed to have influenced vertebrate evolution, polyploidy of contemporary mammals is generally incompatible with normal development and function of all but a few tissues. The production of tetraploid (4n) embryos has become a common experimental manipulation in the mouse. Although development of tetraploid mice has generally not been observed beyond midgestation, tetraploid:diploid (4n:2n) chimeras are widely used as a method for rescuing extraembryonic defects. The tolerance of tissues to polyploidy appears to be dependent on genetic background. Indeed, the recent discovery of a naturally tetraploid rodent species suggests that, in rare genetic backgrounds, mammalian genome duplications may be compatible with the development of viable and fertile adults. Thus, the range of developmental potentials of tetraploid embryos remains in large part unexplored. Here, we review the biological consequences and experimental utility of tetraploid mammals, in particular the mouse.

Animals↗
PubMed2005

Simple and efficient production of mice derived from embryonic stem cells aggregated with tetraploid embryos.

Six newly derived hybrid mouse embryonic stem (ES) cell lines and two inbred ES cell lines were tested for their ability to produce completely ES cell-derived mice by aggregation of ES cells with tetraploid embryos. Forty-five ES cell-tetraploid pups were generated from six hybrid ES cell lines and no pups from two inbred ES cell lines. These pups were found to have increased embryonic and placental weights than control mice. Twenty-two pups survived to adulthood and produced normal offsprings, and the other 23 pups died of several reasons including respiratory distress, abdomen ulcer-like symptoms, and foster failure. The 22 adult ES cell-tetraploid mice were completely ES cell-derived as judged by coat color and germline transmission, only two of them was found to have tetraploid component in liver, blood, and lung as analyzed by microsatellite loci. Our data suggested that genetic heterozygosity is a crucial factor for postnatal survival of ES cell-tetraploid mice, and tetraploid embryo aggregation using hybrid ES cells is a simple and efficient procedure for immediate generation of targeted mouse mutants from genetically modified ES cell clones, in contrast to the standard protocol, which involves the production of chimeras and several breeding steps.

Animals↗
PubMed1989

Methylation of ribosomal cistrons in diploid and tetraploid Odontophrynus americanus (Amphibia, Anura).

Odontophyrynus americanus (Amphibia, Anura) genomic DNA from diploid and tetraploid specimens was treated with restriction enzymes sensitive to cytosine and adenine methylation (5 meC and 6 meA). In both diploids and tetraploids a high proportion of the total DNA was not cleaved by 5 meC-sensitive enzymes as observed on agarose gels stained with ethidium bromide. The DNAs were transferred to nitrocellulose filters and hybridized with cloned fragments containing sequences of Xenopus laevis 28S and 18S ribosomal DNA (rDNA). A high level of methylation of the ribosomal repeat units was revealed by 5 meC-sensitive enzymes in blood, liver, kidney and testis tissues. Adenine was methylated to a lesser degree and similarly in the rDNA from both germinative and somatic tissues. Comparison of the results obtained with DNA of diploids and tetraploids showed that methylation of ribosomal genes was increased in tetraploid genomes of adult frogs, but exact quantitative determinations could not be performed by this methodology. Cloning of the 28S region of the rDNA repeat unit was performed in the lambda gtWES lambda C vector. Restriction patterns obtained with methylation-sensitive enzymes using diploid and tetraploid derived clones confirmed the high level of methylation of the corresponding region of the ribosomal repeat unit in genomic DNAs. The implications of these results in the regulation of expression of the ribosomal genes in diploids and tetraploids are discussed.

Adenine↗
PubMed2005

In vitro induction of tetraploid plants from diploid Zizyphus jujuba Mill. cv. Zhanhua.

Tetraploid plants of Zizyphus jujuba Mill. cv. Zhanhua were obtained with in vitro colchicine treatment. Shoot tips from in vitro-grown plants were treated with five different concentrations of colchicine (0.01, 0.03, 0.05, 0.1, 0.3%) in liquid MS medium (Murashige and Skoog 1962), and shaken (100 rpm) at 25 degrees C in darkness for 24, 48, 72 or 96 h, respectively. Tetraploids were obtained at a frequency of over 3% by using 0.05% colchicine (48 h, 72 h) and 0.1% colchicine (24 h, 48 h) treatment as determined by flow cytometry. Cytological and morphological evidence confirmed the results of flow cytometric analysis. The chromosome number of diploid plants was 24 and that of tetraploid plants was 48. The stomata sizes of tetraploid plants were significantly larger than those of diploid plants, while the frequency of stomata were reduced significantly. Similarly, the chloroplast number of guard cells of tetraploid plants increased significantly. The selected tetraploid plants were grafted onto mature trees of Z. jujuba Mill. cv. Zhanhua in the field, resulted in thicker stems, rounder and succulent leaves, larger flowers and a delay in florescence time (3-4 days later) than diploid plants.

Cell Nucleus↗
PubMed2005

Multiple origins of tetraploid taxa in the Eurasian Bufo viridis subgroup.

We used Q-banding and analyzed nucleolar organizing regions (NORs) to study the cytogenetic evolution of tetraploids within the Palearctic Bufo viridis subgroup, the only known amphibian complex comprising di-, tri- and tetraploid bisexually reproducing taxa. We examined three diploid (2n) nominal taxa (Bufo viridis viridis, B. v. turanensis, B. v. kermanensis) from five Eurasian localities and six tetraploid (4n) nominal taxa (B. oblongus, B. o. danatensis, B. pewzowi pewzowi, B. p. taxkorensis, B. p. unicolor, B. p. strauchi) from eight Central Asian localities. Homeologous chromosomes of 2n and 4n toads exhibit a similar morphology. Silver-staining and in situ hybridization revealed terminal NORs in the long arms of chromosomes 6 in all 2n but in only two out of four chromosomes 6 in all 4n taxa. Q-banding and a rapidly evolving mitochondrial marker suggest at least two origination events for Asian 4n toads: "Western Central Asian tetraploids" (B. oblongus Nikolsky, 1896) exhibit distinct differences within some chromosome quartets, which are divisible into pairs of chromosomes and may be allopolyploid. In contrast, "Central Asian tetraploids" (B. pewzowi Bedriaga, 1898) showed homogenous Q-banding patterns within each quartet, suggesting autopolyploidy. In Northeastern Iran, we discovered a zone of either common ancestry or hybridization of 2n and Western Central Asian 4n toads. This raises intriguing questions about how diploid and tetraploid taxa may evolve by exchanging genetic material.

Animals↗
PubMed2004

Development of in vivo derived diploid and tetraploid pig embryos in a modified medium NCSU 37.

The aim of this study was to assess development of diploid and tetraploid in vivo derived pig embryos cultured in a modified medium NCSU 37 in an atmosphere with reduced concentration of oxygen. The tetraploid embryos were produced by electrofusion of two-cell embryos that had been cultured in vitro from the one-cell stage before fusion (cultured two-cell embryos) or by fusion of freshly recovered two-cell embryos. Development to blastocyst stage of tetraploid embryos, generated from the cultured two-cell embryos was significantly inferior to the development of control one-cell embryos (29.1 +/- 9.7% versus 66.8 +/- 9.7%; P < 0.05). However, development of tetraploid embryos produced from the freshly recovered two-cell embryos and control two-cell embryos was very similar (89.9 +/- 6.1% versus 81.3 +/- 3.4%). Detection of chromosomes 1 and 10 by in situ hybridization showed that more than 85% of the cultured control embryos were diploid while 15% of the embryos were mosaic. Among the fused embryos 50% were tetraploid, 29% mosaic and 21% diploid. These data indicate that the modified medium NCSU 37 provides optimum environment for pre-implantation development of pig diploid and tetraploid embryos.

Animals↗
PubMed2005

Analysis of fatty acid steryl esters in tetraploid and hexaploid wheats: identification and comparison between chromatographic methods.

Fatty acid steryl esters (FASE) in whole meal of 14 genotypes of tetraploid wheats (Triticum dicocconand T. durum) and 17 genotypes of hexaploid wheats (T. spelta and T. aestivum) were analyzed using different chromatographic strategies. By both GC-FID and HPLC-ELSD, tetraploid wheats are lacking two major peaks. The amounts of FASE, calculated on the basis of the GC-FID analysis, were double in hexaploid species as compared to tetraploids (40 and 20 mg/100 g db, respectively). HPLC with ESI-MS detection enabled the identification of FASE by the characteristic fragmentations and ion-adducts of each molecule. The distribution of steryl residues was not different between the wheat species: the main class of steryl derivatives found was the beta-sitosteryl derivatives, followed by campesteryl derivatives with small amounts of stigmasteryl esters. The esterified fatty acids explain the difference between the hexaploid and tetraploid wheats. In particular, small amounts of campesteryl and beta-sitosteryl, while no trace of stigmasteryl palmitates, were found in T. durum or its hulled ancestor T. dicoccon. Steryl oleates were not detectable in T. aestivum or its hulled ancestor T. spelta, which is consistent with the filogenesis of tetraploid and hexaploid species. Both chromatographic techniques (GC and HPLC) showed that FASE are useful to discriminate between hexaploid and tetraploid wheats from both qualitative and quantitative points of view.

Chromatography↗