Risk assessment of outcrossing of transgenic rapessed to related species:

Summary The risk for a gene dispersal is reported for reciprocal crosses between a transgenic rapeseed variety resistant to the herbicide phosphinotricin and five related species. The first stages after pollination were cytologically observed and fertilized ovaries were established in in vitro culture for the production of interspecific hybrids. A similar classification was observed for the index of pollination compatibility and embryo yield. From the 243 embryos produced, 109 plantlets were obtained in a greenhouse. All the interspecific combinations tested were able to produce hybrid plants. A higher number of hybrids was obtained when rapeseed was used as the female parent. The hybrids had the expected triploid structure except for two amphidiploid, B. napus × B. oleracea, and one amphidiploid, B. napus × S. arvensis, plants with 56 chromosomes. The triploid hybrids were sterile or partially fertile but two of the amphidiploid plants, B. napus × B. oleracea, were fully fertile. The cytoplasm source did not seem to affect the fertility of the hybrids.     

Wide mapping of a T-DNA insertion site in oilseed rape using bulk segregant analysis and comparative mapping

Doubled haploid oilseed rape lines segregating for a transgene inducing herbicide resistance (bar gene) were investigated for the wide mapping of the T-DNA insertion site. Bulk segregant analysis using presence/absence and intensity polymorphisms between the bulks, as well as comparative mapping with a linkage group deriving from another cross, led to the identification of 11 random amplified polymorphic DNA (RAPD) markers tightly or loosely linked to the bar gene. Ten RAPD loci out of 11 were located on the same side of the bar locus, strongly suggesting that the T-DNA integrated in a telomeric or subtelomeric position. The eleventh RAPD marker exhibited a strong segregation distortion, which could be the result of a heteroduplex formation. Comparison of the linkage groups obtained from the two crosses showed different recombination rates between markers, possibly reflecting differences in parental genetic backgrounds. Consequences and potential applications in transgene dispersal safety assessment studies are discussed.     

Efficient analysis of egg yolk proteins and their thermal sensitivity using sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing and nonreducing conditions

The multiple functional properties of egg yolk are mostly influenced by its complex protein composition. The high lipid content of egg yolk as well as the low solubility of delipidated egg yolk lipoproteins make analysis by conventional chromatographic or electrophoretic techniques a difficult task. This work describes a method to profile egg yolk proteins after delipidation with acetone using sodium dodecyl sulfate polyacrylamide gel electrophoresis on precast 8-18% T polyacrylamide gradient gels. Twenty bands were obtained for the whole egg yolk profile with molecular weights ranging between 5 and 221 kDa. The bands were identified based on their molecular weight and by comparison with isolated egg yolk subfractions. The dissociation behavior under reducing and nonreducing conditions provided additionally helpful information for identification and characterization of the yolk proteins. The method presented is very well suited for assaying the thermal sensitivity of whole yolk and its components and thus for the characterization of heat treatment processes.     

Acrylamide formation from asparagine under low moisture Maillard reaction conditions. 2. Crystalline vs amorphous model systems

The formation of acrylamide was investigated in model systems based on asparagine and glucose under low moisture Maillard reaction conditions as a function of reaction temperature, time, physical state, water activity, and glass transition temperature. Equimolar amorphous glucose/asparagine systems with different water activities were prepared by freeze drying and were shown to quickly move to the rubbery state already at room temperature and a water activity of above 0.15. The acrylamide amounts were correlated with physical changes occurring during the reaction. Pyrolysis and kinetics of acrylamide release in amorphous and crystalline glucose/asparagine models indicated the importance of the physical state in acrylamide formation. In amorphous systems, acrylamide was generated in higher concentrations and at lower temperatures as compared to the crystalline samples. Time and temperature are covariant parameters in both systems affecting the acrylamide formation by thermal processes. On the other side, the water activity and glass transition temperature do not seem to be critical parameters for acrylamide formation in the systems studied.     

Seasonal and phenological variations of the essential oil from the narrow endemic species Artemisia molinieri and its biological activities

The volatile components of the aerial parts of Artemisia molinieri, an endemic wormwood of southern France, were analyzed by GC and GC-MS. Among the 69 compounds identified, major components were ascaridole (19-76%), alpha-terpinene (traces-36%), p-cymene (1-17%), 1,8-cineole (0.3-8%), and germacrene D (0.6-15%). Quantitative variations have been characterized following the season, the phenological cycle, and the aging of the plants. Bioassays have been performed on a sample of essential oil, which has shown a strong inhibition of the growth of both tested yeasts (Candida albicans and Saccharomyces cerevisiae var. chevalieri) and minor activity on both tested Gram-negative bacteria (Escherichia coli and Enterococcus hirae). The oils have shown interesting antioxidant activities on the basis of alpha-tocopherol as reference compound, up to 400-1200%.     

Synthetic clonal reproduction through seeds

Cloning through seeds has potential revolutionary applications in agriculture, because it would allow vigorous hybrids to be propagated indefinitely. However, asexual seed formation or apomixis, avoiding meiosis and fertilization, is not found in the major food crops. To develop de novo synthesis of apomixis, we crossed Arabidopsis MiMe and dyad mutants that produce diploid clonal gametes to a strain whose chromosomes are engineered to be eliminated after fertilization. Up to 34% of the progeny were clones of their parent, demonstrating the conversion of clonal female or male gametes into seeds. We also show that first-generation cloned plants can be cloned again. Clonal reproduction through seeds can therefore be achieved in a sexual plant by manipulating two to four conserved genes.     

Identification and synthesis of 2-heptanethiol, a new flavor compound found in bell peppers

2-Heptanethiol was identified for the first time as a constituent of red and green bell pepper extracts. The chemical structure of this new aroma compound was proposed on the basis of mass spectra and retention indices and confirmed by chemical synthesis and nuclear magnetic resonance spectroscopy measurements. Its aroma properties were described as sulfury, onion-like, and vegetable-like, reminiscent of bell pepper at lower concentrations, with an orthonasal detection threshold of 10 microg/L of water. No differences in odor note and threshold value were observed for the enantiomeric forms, which were prepared from enantiopure 2-heptanol by tosylation, followed by thioacetylation and reduction, giving the target thiol enantiomers.     

Detailed physicochemical characterization of the 2S storage protein from rape (Brassica napus L.)

Chromatographic, chemical, and spectroscopic techniques were used to characterize the physicochemical properties of napin purified by preparative chromatography. The molar extinction coefficient was determined (epsilon = 0.56), and static and dynamic light scattering measurements enabled the average molecular weight (M(w) = 13919), the second virial coefficient (A(2) = 23.95 x 10(-)(5) mol cm(3) g(-)(2)), and the hydrodynamic radius (R(H) = 1.98 nm) to be determined. No conformational changes were observed by fluorescence and circular dichroism measurements in different buffers at pH 3, 4.6, 7, and 12, confirming the high pH stability of this protein. From MALDI-TOF analysis and after enzymatic digestion, it was found that this purified sample, extracted from the rapeseed variety Express, contained mainly isoform 2SS3_BRANA.     

Evolution des proprietes germinatives des semences de graminees pendant et apres leur maturation

Résumé Tout au long de la période de maturation, des grains de blé et de maïs ont été récoltés à des intervalles de temps réguliers et mis à germer. Afin de comparer les propriétés germinatives des différents échantillons, on a choisi comme critère le temps moyen de germination, calculé lorsque 90% des graines ont effectivement germé (T.M.G./90). Cette grandeur et l'intensité de la dormance varient toujours dans le même sens, que la seconde agisse en ralentissant la vitesse de germination ou qu'elle produise une diminution de la faculté germinative.Nous avons mis en évidence chez le maïs, et davantage encore chez les blés roux, que T.M.G./90 passe par un minimum, puis réaugmente significativement, et diminue à nouveau jusqu'à atteindre sa valeur normale. Le minimum a lieu aux environs du stade laiteux ou pâteux, et le maximum juste avant ou pendant la dessiccation des grains. Cette évolution de la dormance semble être en relation avec le métabolisme de certaines substances de croissance, celui-ci dépendant à son tour des besoins, changeants, de l'embryon en oxygène et de la perméabilité, variable, des téguments vis à vis de gaz.

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Summary Throughout the ripening period, wheat and maïze grains were gathered at regular time intervals and put to germinate. In order to compare the germination properties of the various samples we took as a criterion the Mean Germination Time, computed when 90% of the seeds have completed germination (MGT/90). This ratio always varies in the same way as the intensity of dormancy, the latter acting either by moderating the germination speed or by causing a decrease of the germinative ability.We have brought into evidence that in maïze, and still more in red wheats, MGT/90 goes through a minimum, then increases significantly before it falls again so as to reach its normal value. The minimum takes place at about the time of the milky or the doughy stage, and the maximum just before or during the desiccation of the grains. This evolution of dormancy appears to be correlated with the metabolism of particular growth substances, and the latter is itself coupled with fluctuating oxygen needs of the embryo and a varying permeability of the teguments to this gas.

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Zusammenfassung Während des Reifens wurden Weizen- und Maiskörner in bestimmten Zeitabständen den Ähren entnommen und zum Keimen gebracht. Um die Keimeigenschaften der verschiedenen Proben vergleichen zu können, hat man als Maßstab die Mittlere Keimungszeit (MKZ/90 oder TMG/90 genommen, die aus der 90%igen Keimung untersuchter Körner errechnet wurde. Diese Größe verändert sich nämlich immer in dergleichen Richtung wie der Grad der Keimruhe, so daß die letztere entweder aus einem Verlangsamen der Keimung oder einer Verminderung der Keimfähigkeit besteht.Wir haben dargelegt, daß im Mais und vor allem im gelbroten Weizen die MKZ/90 erst ein Minimum passiert, um dann bedeutend anzuwachsen, bevor sie wieder bis zur normalen Größe absinkt. Das Minimum wird etwa beim Milch- oder Teigstadium erreicht, das Maximum kurz vor oder während des Trockenwerdens des Korns. Diese Keimschwankungen scheinen im Zusammenhang zu stehen mit einem veränderten Sauerstoffbedarf des Embryos und einer wechselnden Sauerstoffdurchlässigkeit der Tegumente in Verbindung mit dem Metabolismus gewisser Wachstumsubstanzen.

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avec 5 figs.

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Communication faite au Symposium International de Greifswald, Septembre 1963.