Search results for "actions"

Proper triangular Ga-actions on A^4 are translations

2013

We describe the structure of geometric quotients for proper locally triangulable additve group actions on locally trivial A^3-bundles over a noetherian normal base scheme X defined over a field of characteristic 0. In the case where dim X=1, we show in particular that every such action is a translation with geometric quotient isomorphic to the total space of a vector bundle of rank 2 over X. As a consequence, every proper triangulable Ga-action on the affine four space A^4 over a field of characteristic 0 is a translation with geometric quotient isomorphic to A^3.

Immunologische Grundlagen der allergischen Spätreaktion

1965

An transferaktiven Zellen von tb-sensibilisierten Tieren sind mindestens zwei distinkte zellstandige Antikorper nachweisbar. Eine Art dieser Antikorper ist gegen Tuberkulopolysaccharid und die andere gegen Tuberkuloprotein gerichtet. Sie haben beide nach Kontakt mit dem Antigen die Fahigkeit, Komplement zu binden. Eine Cytolyse kommt sowohl durch eine zellstandig ablaufende Immunreaktion zwischen Polysaccharid-Antikorper und Tuberkuloprotein-Antikorper mit dem Antigen zustande, jedoch ist dazu nur im letzteren Falle Komplement erforderlich. Nach Kontakt mit dem Antigen ist also beim Polysacharid-Antikorper eine Komplementbindung moglich, fur eine Cytolyse aber nicht notig. Die beiden zellst…

Antigens of <i>Euparipha pisana</i> (Snail)

1988

The data obtained in this study suggest that eating <i>Euparipha pisana</i> (snail), a common food in Mediterranean countries, could give serious allergic reaction such as asthma. We describe here the identification and partial characterization of allergenic molecules form this new source. An aqueous extract of snail was obtained by homogenization in distilled water, centrifugation, dialysis and defatting with ethyl ether. Skin prick test (SPT) performed with the snail extract on 70 subjects allergic to the more common allergens of the Mediterranean area gave a SPT positivity in 61% of the subjects tested, with a mean value of histamine-equivalent prick (HEP) equal to 0.81 ± 0.2…

Investigation of the aqueous transmetalation of π-allylpalladium with indium salt: the use of the Pd(OAc)2–TPPTS catalyst

2005

pi-Allylpalladium complexes could be generated in water by the palladium(0) water soluble catalyst prepared in situ from palladium acetate and TPPTS. These complexes were transmetalated with indium to react with benzaldehyde. The aqueous solution of Pd(0)(TPPTS)(n) could be reused without deterioration of the catalyst in the first and second recycling. The system proved to be efficient with primary and secondary allylic substrates. The stereochemical outcome of the allylation through umpolung of allylpalladium, was also studied using models with a restraint conformation.

THE BEHAVIORAL RESPONSE OF AMPHIPODS HARBORING CORYNOSOMA CONSTRICTUM (ACANTHOCEPHALA) TO VARIOUS COMPONENTS OF LIGHT

2006

Many studies have shown that photic behavior of amphipods is subject to parasitic manipulation. However, all these investigations have focused on but one property of light (i.e., intensity). This study investigated the possibility that variable wavelength sensitivity, as a potentially important component of amphipod ecology, is subject to parasitic manipulation. The photic behavior of freshwater amphipods Hyalella azteca, infected with the duck acanthocephalan Corynosoma constrictum, was tested. The phototactic responses of infected and uninfected amphipods to various wavelengths in the visible spectrum were compared, and to delineate the effects of intensity and wavelength on behavior, the…

Carotenoids of two freshwater amphipod species (Gammarus pulex and G. roeseli) and their common acanthocephalan parasite Polymorphus minutus

2004

Carotenoid compositions of two freshwater Gammarus species (Crustacea: Amphipoda) and of their common acanthocephalan parasite Polymorphus minutus were characterized. The effect of carotenoid uptake by the parasite was addressed by comparing the carotenoid content of uninfected and infected female hosts. Using high-pressure liquid chromatography (HPLC), co-chromatography of reference pigments and electron ionization mass spectrometry of collected HPLC fractions (EI-MS), several xanthophylls and non-polar compounds were identified. Seven kinds of carotenoids, mainly xanthophylls, were identified in gammarids. Astaxanthin was predominant, amounting to 40 wt.% of total carotenoid in both uninf…

Amyloid-Like Superstructures: mechanisms of formation and morphologies

2014

Micro-organisms interactome during wine alcoholic fermentation

2022

The study of interactions between microorganisms is of major interest in oenology for various applications, including the modulation of the aromatic profile of wines. The interactions between Saccharomyces and non-Saccharomyces yeasts are widely described in the literature. On the contrary, interactions during alcoholic fermentation between S. cerevisiae strains, known for their technological properties in oenology, have been little studied.In this work, twelve strains of S. cerevisiae and their impact on wine were characterized in pure cultures using an integrative approach that combines microbiological, chemical, metabolomic and sensory approaches. An important intraspecific diversity was…

Cercarial Production of the Trematode Rhipidocotyle fennica in Clams Kept in the Field

1998

The numbers of cercariae that trematodes produce have been previously investigated in the laboratory but not in the field. I studied cercarial production of the bucephalid trematode Rhipidocotyle fennica in the freshwater unionid clam Anodonta piscinalis kept under natural conditions. Naturally infected clams (n = 180) were collected and marked in early June 1996. Every 14 days, starting from the collection date and ending in October, these clams were taken to the laboratory where they were monitored for the emergence of trematode cercariae. Between monitoring dates, the clams were returned to the collection site. From a random subsample of infected clams (n = 12), the number of cercariae p…

Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections.

2004

Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infect…