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Summary: Résumé: Zusammenfassung Possible mechanism(s) of resistance to auxinic herbicides in wild mustard (Sinapis arvensis L.) were investigated by characterizing responses of susceptible and resistant biotypes to 2,4‐D, di‐camba or picloram. No differences between bio‐types were observed in absorption, translocation, or metabolism of foliar‐applied radiolabelled herbicides. In contrast, the levels of ethylene production varied between biotypes. The susceptible biotype produced twofold and sixfold more ethylene than the resistant biotype within 4 h and 44 h of herbicide application, respectively. These results suggest that the mechanism of resistance in wild mustard is not due to differences in absorption, translocation, or metabolism. Ethylene production studies imply that resistance to auxinic herbicides may be attributed to altered target site(s) of action. Bases physiologiques de la résistance aux herbicides auxiniques d'un biotype de moutarde des champs (Sinapis arvensis L.) Les mécanismes possibles de la résistance aux herbicides auxiniques chez la moutarde des champs (Sinapis arvensis L.) ont été recherchés en caractérisant les réponses de biotypes résis‐tants et sensibles au 2,4‐D, au dicamba et au pi‐clorame. Aprés application des herbicides radioactifs sur le feuillage, aucune différence d'absorption, de migration ou de métabolisme n'a été observée. Par contre, la production d'éthylene différait entre les biotypes. Le biotype sensible produisait 2 et 6 fois plus d'éthylène que le biotype sensible, respectivement 4 et 44 heures après l'application d'herbicide. Ces résultats sug‐gèrent que la résistance aux herbicides auxiniques chez la moutarde des champs n'est pas due à des différences d'absorption, de migration ou de métabolisme mais pourrait provenir d'une altération du site d'action. Physiologische Untersuchung der Resistenz eines Acker‐Senf‐(Sinapis arvensis‐) Biotyps gegenüber Wuchsstoffherbiziden Der mögliche Mechanismus der Resistenz gegenüber Wuchsstoffherbiziden beim Acker‐Senf (Sinapis arvensis L.) wurde unhand der Reaktion von empfindlichen und resistenten Biotypen gegenüber 2,4‐D, Dicamba oder Picloram untersucht. Hinsichtlich Absorption, Translokation oder Metabolismus der auf die Blätter applizierten, radioaktiv markierten Her‐bizide wurden keine Unterschiede beobachtet. Die Ethylenbildung variierte jedoch zwischen den Biotypen. Der empfindliche produzierte in‐nerhalb 4 oder 44 Stunden nach der Herbizid‐applikation 2‐bzw. 6mal mehr Ethylen als der resistente. Aus den Ergebnissen läßt sich schließen, daß beim Acker‐Senf der Resisten‐zmechanismus nicht in der Absorption, der Translokation oder dem Metabolismus liegt, sondern die Ethylenbildung daran beteiligt ist, wo die Wirkorte fur die Wuchsstoffherbizide liegen.

Emerging technologies are considering the possible use of Terahertz radiation in different fields ranging from telecommunications to biology and biomedicine. The study of the potential effects of Terahertz radiation on biological systems is therefore an important issue in order to safely develop a variety of applications. This paper describes a pilot study devoted to determine if Terahertz radiation could induce genotoxic effects in human peripheral blood leukocytes. For this purpose, human whole blood samples from healthy donors were exposed for 20 min to Terahertz radiation. Since, to our knowledge, this is the first study devoted to the evaluation of possible genotoxic effects of such radiation, different electromagnetic conditions were considered. In particular, the frequencies of 120 and 130 GHz were chosen: the first one was tested at a specific absorption rate (SAR) of 0.4 mW g-1, while the second one was tested at SAR levels of 0.24, 1.4, and 2 mW g-1. Chromosomal damage was evaluated by means of the cytokinesis block micronucleus technique, which also gives information on cell cycle kinetics. Moreover, human whole blood samples exposed to 130 GHz at SAR levels of 1.4 and 2 mW g-1 were also tested for primary DNA damage by applying the alkaline comet assay immediately after exposure. The results obtained indicate that THz exposure, in the explored electromagnetic conditions, is not able to induce either genotoxicity or alteration of cell cycle kinetics in human blood cells from healthy subjects.

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