Flowering synchronisation between male and female West African cultivated yams (Dioscorea cayenensis-rotundata complex)

It has long been admitted that male and female cultivars of Dioscorea cayenensis-rotundata complex do not flower at the same period and consequently natural outcrossing rarely occurs. Flowering in thirteen (7 males and 6 females) traditional cultivars were studied. Four main results were obtained: i) the first bud emergence occurred 25 days earlier in males; ii) the male and female first flower opening overlapped for 10 days (85 to 95 days after sprouting); iii) for both sexes, highest frequency of flower opening occurred at mid-day; and iv) the female cultivar 1800 could flower for 8 consecutive days, with a peak between day 4 and day 8. These results are discussed in relation to intercrossing success. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antiproliferative activity of violaxanthin isolated from bioguided fractionation of Dunaliella tertiolecta extracts

Dunaliella tertiolecta (DT) was chemically investigated to isolate molecules inhibiting cancer cell proliferation and inducing apoptosis in vitro. The potency to inhibit cell growth was used for the bio-guided fractionation and isolation of active compounds using chromatographic techniques. The DT dichloromethane extract exhibited a strong anti-proliferative activity on MCF-7 and LNCaP cells, and was further fractionated and sub-fractionated by RP-HPLC. High resolution mass spectrometry and spectrophotometric analysis unequivocally identified violaxanthin as the most antiproliferative molecule present in DT DCM extract. Violaxanthin purified from DT induced MCF-7 dose-dependent growth inhibition in continuous and discontinuous treatments, at concentrations as low as 0.1 μg·mL⁻¹ (0.17 μM). Phosphatidylserine exposure, typical of early apoptosis, was observed after 48 h treatment at 8 μg·mL⁻¹ (13.3 μM) but no DNA fragmentation, characteristic of late apoptosis steps, could be detected even after 72 h treatment at 40 μg·mL⁻¹ (66.7 μM). Taken together, our results demonstrate the strong antiproliferative activity of violaxanthin on one human mammary cancer cell line, and suggest that studying the pharmacology of violaxanthin and pharmacomodulated derivatives on cancer cells may allow potent antiproliferative drugs to be obtained.     

Inhibition of Methionine Biosynthesis in Botrytis cinerea by the Anilinopyrimidine Fungicide Pyrimethanil

When mycelium of Botrytis cinerea was treated with low concentrations of the anilinopyrimidine fungicide pyrimethanil the total amount of free amino acids increased. Qualitative variations were also induced: alanine, glutamine, lysine, glycine, histidine, asparagine, arginine, threonine and moreover, α-aminobutyrate and β-alanine were accumulated; cyst(e)ine, valine, leucine and citrulline were reduced. When mycelium of B. cinerea was incubated with Na₂[³⁵S]O₄, pyrimethanil at 1·5 μM induced a decrease of [³⁵S]methionine and simultaneously an increase of [³⁵S]cystathionine. These data indicate that the anilinopyrimidine fungicide pyrimethanil inhibits the biosynthesis of methionine and suggest that the primary target could be the cystathionine β-lyase. © 1997 SCI.     

The stereoisomerism of second generation anticoagulant rodenticides: a way to improve this class of molecules to meet the requirements of society?

Second generation anticoagulant rodenticides (SGAR) are generally highly efficient for rodent management even towards warfarin‐resistant rodents. Nevertheless, because of their long tissue‐persistence, they are very associated with non‐target exposure of wildlife and have been identified as ‘Candidates for Substitution’ by the European Union's competent authority. A promising way to reduce ecotoxicity issues associated to SGAR could be the improvement of SGAR based on their stereoisomery, and due to this improvement, positioning about SGAR might be reconsidered. © 2018 Society of Chemical Industry     

Double dose efficiency of the yellow rust resistance gene Yr17 in bread wheat lines

Yellow rust, caused by Puccinia striiformis f. sp. tritici, is one of the most severe wheat disease worldwide. Crop losses have ranged from 10% to 70% and up to 100% in extreme conditions. Eighty-two resistance genes, designated Yr, have been identified. Among them, Yr17 derived from Aegilops ventricosa and located on chromosome 2A has been widely used in wheat breeding. However, it had been overcome already. Through recombination of the Ae. ventricosa Yr17-carrying 6N^v chromosome with 2D of wheat, we introduced Yr17 onto chromosome 2D. Then, lines carrying Yr17 on both 2A and 2D were generated. Seedlings of the latter, as well as those carrying a single dose of Yr17 either on 2A or on 2D, were inoculated with virulent or avirulent strains on wheat seedlings. The different genotypes were fully susceptible for the two pathotypes that are virulent on Yr17. In the case of avirulent pathotypes, the Yr17 double dose lines were fully resistant, while those with the Yr17 gene only on either 2A or 2D had intermediate resistance reactions towards one or the other or both pathotypes.