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Several strains, which according to their cell wall type and morphology belong to the genus Actinomadura, differ markedly from already recognized species. They are considered to be new taxa: A. libanotica, A. ferruginea, and A. spiralis. Their descriptions and illustrations are presented.

Thirty-nine isolates and additional reference strains of methanotrophic bacteria were studied with respect to mol % G + C of their DNA and the type of intracytoplasmatic membranes. The results on the whole confirm the former classification scheme of Whittenbury et al. (1970). However, problematic groups such as “Methylocystis” and “Methylobacter” are in need of additional taxonomic studies.

We have analyzed 210 lambda-producing hybridomas derived from lipopolysaccharide-stimulated spleen cells from a single kappa-suppressed mouse. All were classified as lambda 1, lambda 2 or lambda 3 with the exception of four unusual lines. Two of these were due to V lambda 2 J lambda 1 and the other two to V lambda 2 J lambda 3 rearrangements. The lines were clonally independent since the point of VJ recombination in each one was different. Southern blot analysis of the V lambda 2 C lambda 1-producing lines showed no evidence for an inversion. Under the assumption of a simple deletion model of rearrangement these findings place the V lambda 2 cluster upstream of the V lambda 1 cluster oriented in the same direction.