Parathymische Lymphknoten der Maus und ihre Reaktion auf Thymektomie

Summary The effect of complete and partial, neonatal thymectomy on parathymic lymphnodes was investigated in NMRI-mice. The results indicate that neonatal extirpation of thymic tissue causes an increase in size and number of parathymic lymphnodes.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.

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Herrn Prof. Dr.O. Westphal zum 60. Geburtstag.     

Experimental allergic encephalomyelitis (EAE)-changes in structure and proliferation in rat lymph nodes after sensitization with guinea-pig and bovine basic myelin protein

Summary Substantial difference in the proliferation of lymphoid cells in the draining LN was found in rats injected with guinea-pig EBP-FCA and bovine NBP-FCA indicating significance of the encephalitogenic determinant in the myelin basic protein in the peripheral lymphatic reaction initiating EAE.     

Rag mutations reveal robust alternative end joining

Mammalian cells repair DNA double-strand breaks (DSBs) through either homologous recombination or non-homologous end joining (NHEJ). V(D)J recombination, a cut-and-paste mechanism for generating diversity in antigen receptors, relies on NHEJ for repairing DSBs introduced by the Rag1-Rag2 protein complex. Animals lacking any of the seven known NHEJ factors are therefore immunodeficient. Nevertheless, DSB repair is not eliminated entirely in these animals: evidence of a third mechanism, 'alternative NHEJ', appears in the form of extremely rare V(D)J junctions and a higher rate of chromosomal translocations. The paucity of these V(D)J events has suggested that alternative NHEJ contributes little to a cell's overall repair capacity, being operative only (and inefficiently) when classical NHEJ fails. Here we find that removing certain portions of murine Rag proteins reveals robust alternative NHEJ activity in NHEJ-deficient cells and some alternative joining activity even in wild-type cells. We propose a two-tier model in which the Rag proteins collaborate with NHEJ factors to preserve genomic integrity during V(D)J recombination.     

The cellular sources of antibodies in diffusion chamber cultures of alveolar exudates

Zusammenfassung Alveolarexsudatzellen von Kaninchen wurden zusammen mit Schaferythrozyten in Diffusionskammern gebracht und diese in neugeborene Kaninchen implantiert. Antikörperbildende Zellen wurden in den Diffusionskammern und im Omentum der Rezipienten festgestellt.     

Electrostatic trapping of ammonia molecules

The ability to cool and slow atoms with light for subsequent trapping allows investigations of the properties and interactions of the trapped atoms in unprecedented detail. By contrast, the complex structure of molecules prohibits this type of manipulation, but magnetic trapping of calcium hydride molecules thermalized in ultra-cold buffer gas and optical trapping of caesium dimers generated from ultra-cold caesium atoms have been reported. However, these methods depend on the target molecules being paramagnetic or able to form through the association of atoms amenable to laser cooling, respectively, thus restricting the range of species that can be studied. Here we describe the slowing of an adiabatically cooled beam of deuterated ammonia molecules by time-varying inhomogeneous electric fields and subsequent loading into an electrostatic trap. We are able to trap state-selected ammonia molecules with a density of 10(6) cm(-3) in a volume of 0.25 cm3 at temperatures below 0.35 K. We observe pronounced density oscillations caused by the rapid switching of the electric fields during loading of the trap. Our findings illustrate that polar molecules can be efficiently cooled and trapped, thus providing an opportunity to study collisions and collective quantum effects in a wide range of ultra-cold molecular systems.