The early phases of ontogeny are decisive for the development of the B-cell repertoire. Here, we demonstrate that maternal tertiary immunization of BALB/c mice with 2-phenyloxazolone (phOx) caused a drastic alteration of the primary antigen-specific repertoire of the offspring. Maternal tertiary immunization or quaternary antibodies, which exhibited an extremely weak cross-reactivity with the major Ox1 idiotype (IdOx1), induced a change in the proportion of IdOx1/non-IdOx1 antiphOx antibodies in the F1 and F2 primary repertoire. The observed variability in the level of IdOx1 expression (10-90%) exceeded even the seemingly genetically based differences between various mouse strains. In comparison with the non-IdOx1 of control mice, half of the non-IdOx1 antibodies showed a 5-100-fold enhanced affinity. Sixty per cent of these antibodies exhibited an affinity identical to that of IdOx1 antibodies, which are normally of the highest affinity, while the remaining 40% exceeded even that of IdOx1 by a factor of 10. The non-IdOx1 were encoded by VH/VL genes and/or combinations thereof which are either new, hitherto unobserved in the antiphOx response, or typical of memory responses in normal mice. The significance of these data is discussed with respect to the possibility that maternal antibodies, which are acquired through multiple immune maturation processes, may have an epigenetic (non-Mendelian) inheritable potential for the offspring.

Chromosomal DNA from Actinomyces viscosus was digested with restriction endonucleases and the fragments ligated with pUC-vectors were used to transform Escherichia coli cells. Clones bearing the required sialidase gene were detected by spraying the colonies with the fluorogenic sialidase substrate MU-Neu5Ac.The identity of the cloned sialidase was confirmed after the 5700-fold enrichment and comparison with the purified enzyme of A. viscosus. Both sialidases were identical with regard to molecular mass, substrate specificity tested with sialyllactoses, and the inhibition of their activity by heterologous antisialidase antibodies. The sequenced insert (EMBL accession number X62276) revealed a mol% G + C of 68.2, typical for A.viscosus. An open reading frame of 2739 bp follows a sequence with dyad symmetry and an AG-rich region, and codes for 913 amino acids representing a molecular mass of 113 kDa.The conserved amino acid sequence [Ser-X-Asp-X-Gly-X-Thr-Trp] typical for bacterial sialidases was found at five positions in the predicted amino acid sequence. The gene of this enzyme is expressed by E. coli, despite the low relatedness of both species. Klonierung, Sequenzanalyse und Expression des Sialidase-G ens aus Actinomyces viscosus DSM 43798Zusammenfassung: Chromosomale DNA von Actinomyces viscosus wurde mit Restriktionsendonucleasen verdaut und die Fragmente in pUC-Vektoren ligiert, welche zur Transformation von E. co/z-Zellen verwendet wurden. Die gesuchten Klone, die das Sialidase-Gen enthielten, wurden anhand der Enzymaktivität mit dem fluorogenen Sialidasesubstrat MUNeuSAcdetektiert.Die Identität der klonierten Sialidase wurde nach 5 700-facher Anreicherung durch Vergleich mit dem angereicherten Enzym von Actinomyces viscosus bestätigt. Beide Sialidasen waren identisch bezüglich der Molekularmasse, der Substratspezifität getestet