Chironomid pupal exuviae and larvae of two storage reservoirs in The Netherlands

For three years chironomid larvae were collected bimonthly with a grab sampler in two deep storage reservoirs in The Netherlands. Chironomid pupal exuviae were collected monthly, from April to November, with a handnet. Net samples yielded more taxa than grab samples. The taxa found in net samples originated from more habitats, than taxa found in grab samples. The relative contribution of Orthocladiinae was much larger in net samples. Based on the results obtained in the two reservoirs, some advantages and disadvantages of both sampling methods are discussed.     

The anti-conflict effect of cyproheptadine is not mediated by its 5-hydroxytryptamine antagonistic property

Cyproheptadine, a 5HT2 receptor antagonist with prominent antimuscarinic and anti-histaminic properties, was shown to have an anti-conflict effect in rats using a modified Geller-Seifter test and also enhanced extinction of conflict behaviour. The selective 5HT2 receptor antagonist ritanserin, however, had neither an anti-conflict effect nor an effect on extinction of conflict behaviour. The muscarinic receptor antagonist scopolamine, on the other hand, was active in both paradigms. The effect of cyproheptadine on extinction of conflict behaviour was decreased by co-administration of physostigmine, an acetylcholinesterase inhibitor, but not affected by the concomitant administration of the muscarine receptor agonist oxotremorine. The results suggest that the anti-conflict effect of cyproheptadine has to be ascribed to its anti-muscarinic activity and is not due to its 5HT2 antagonism.     

Spectroscopy on individual light-harvesting 1 complexes of Rhodopseudomonas acidophila

In this paper the fluorescence-excitation spectra of individual LH1-RC complexes (Rhodopseudomonas acidophila) at 1.2 K are presented. All spectra show a limited number of broad bands with a characteristic polarization behavior, indicating that the excitations are delocalized over a large number of pigments. A significant variation in the number of bands, their bandwidths, and polarization behavior is observed. Only 30% of the spectra carry a clear signature of delocalized excited states of a circular structure of the pigments. The large spectral variety suggests that besides site heterogeneity also structural heterogeneity determines the optical spectrum of the individual LH1-RC complexes. Further research should reveal if such heterogeneity is a native property of the complex or induced during the experimental procedures.