The prevalent occurrence of herbicide resistant weeds increases the necessity for new site of action herbicides for effective control as well as to relax selection pressure on the known sites of action. As a consequence, interest increased in the unexploited molecule cinmethylin as a new solution for the control of weedy grasses in cereals. Therefore, the mechanism of action of cinmethylin was reevaluated. We applied the chemoproteomic approach cellular Target Profiling™ from Evotec to identify the cinmethylin target in Lemna paucicostata protein extracts. We found three potential targets belonging to the same protein family of fatty acid thioesterases (FAT) to bind to cinmethylin with high affinity. Binding of cinmethylin to FAT proteins from Lemna and Arabidopsis was confirmed by fluorescence-based thermal shift assay. The plastid localized enzyme FAT plays a crucial role in plant lipid biosynthesis, by mediating the release of fatty acids (FA) from its acyl carrier protein (ACP) which is necessary for FA export to the endoplasmic reticulum. GC-MS analysis of free FA composition in Lemna extracts revealed strong reduction of unsaturated C18 as well as saturated C14, and C16 FAs upon treatment with cinmethylin, indicating that FA release for subsequent lipid biosynthesis is the primary target of cinmethylin. Lipid biosynthesis is a prominent target of different herbicide classes. To assess whether FAT inhibition constitutes a new mechanism of action within this complex pathway, we compared physiological effects of cinmethylin to different ACCase and VLCFA synthesis inhibitors and identified characteristic differences in plant symptomology and free FA composition upon treatment with the three herbicide classes. Also, principal component analysis of total metabolic profiling of treated Lemna plants showed strong differences in overall metabolic changes after cinmethylin, ACCase or VLCFA inhibitor treatments. Our results identified and confirmed FAT as the cinmethylin target and validate FAT inhibition as a new site of action different from other lipid biosynthesis inhibitor classes.

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SummaryThe problem of polar and subpolar inversions is attacked. Thus a literature review of the exploration of the polar lower atmosphere is presented together with an attempt to classify these inversions, according to the participating processes, such as subsidence, advection and radiation. These physical processes are incorporated into a simple inversion model, giving the heights of inversion and cloud base, the radiative cooling rates and the vertical profiles of the thermodynamic quantities and the turbulent fluxes. The model is applied to a period with subsidence inversion over the Norwegian Sea during summer. The case study shows a good agreement between the results of the steady-state model and the mean observed thermodynamic structure of the atmospheric boundary layer. Zusammenfassung Die Struktur der subpolaren Inversionen in der atmosphiirischen GrenzschichtDie Erforschung der polaren und subpolaren atmosphfirischen Grenzschicht wird in einer Literaturiibersicht dargestellt. Anhand der bei der Entstehung beteiligten Prozesse wie grot~skaliges Absinken, Advektion und Strahlung wird eine Einteilung der Inversionen vorgenommen. Mit einem einfachen Modell, das diese Prozesse berticksichtigt, wird eine sommerliche Inversionslage fiber der Norwegischen See untersucht. Das Modell liefert die H6hen yon Inversion und Wotkenbasis, die Strahlungsabktihlung und die Vertikalproffle der thermodynamischen Zustandsgr6gen und der turbulenten Fliisse. Die Modellergebnisse zeigen eine gute (Ybereinstimmung mit den Beobachtungen.

In the summer of 1988/89 flights were carried out in the Coorong coastal area of South Australia to investigate sea-breeze fronts. The flights yielded data sets of the structure of the fronts in the cross-frontal direction with a spatial resolution of approximately 3 m. The study is focused on the budgets of sensible and latent heat in the vicinity of the front and on frontogenesis/frontolysis processes which are closely related to budget considerations.The frontogenesis relationships and the budgets were established on a 2 km length scale by low-pass filtering of the space series. As the wind components were measured with high accuracy, all processes which determine frontogenesis could he evaluated and are displayed in x,z-cross-sections: these are the confluence, shear and diabatic effects, all of which play a role in aqlax-, aqlaz-, de/ax-as well as Waz-frontogenesis. A detailed analysis is given for two different states of frontal development. The presented results shed much light on the governing physical processes in the frontal region with strong emphasis on the effects of confluence-generated updrafts, on shear instabilities causing bulges and clefts in the frontal surface as well as producing the elevated frontal head, and on processes related to differential heating and moistening.