In our previous paper (Kimura, Y., et al., Biosci. Biotechnol. Biochem., 67, 1852-1856, 2003), we found that a complex type N-glycans containing beta1-3 galactose residue occurs on royal jelly glycoproteins. During structural analysis of minor components of royal jelly N-glycans, we found complex type N-glycans bearing both galactose and N-acetylgalactosamine residues. Detailed structural analysis of pyridylaminated oligosaccharide revealed that the newly found N-glycan had a complex type structure harboring a tumor marker (T-antigen) unit: Galbeta1-3GalNAcbeta1-4GlcNAcbeta1-2Manalpha1-6 (Galbeta1-3GalNAcbeta1-4GlcNAcbeta1-2Manalpha1-3) Manbeta1-4GlcNAcbeta1-4GlcNAc. To our knowledge, this may be the first report of the presence of the T-antigen unit in the N-glycan moiety of eucaryotic glycoproteins.

In a previous study (Y. Kimura et al., Biosci. Biotechnol. Biochem., 70, 2583-2587, 2006), we found that new complex type N-glycans harboring Thomsen-Friedenreich antigen (Galbeta1-3GalNAc) unit occur on royal jelly glycoproteins, suggesting the involvement of a new beta1-3galactosyltransferase in the synthesis of the unusual complex type N-glycans. So far, such beta1-3galactosyltransferase activity, which can transfer galactosyl residues with the beta1-3 linkage to beta1-4 GalNAc residues in N-glycan, has not been found among any eucaryotic cells. But using GalNAc(2)GlcNAc(2)Man(3)GlcNAc(2)-PA as acceptor N-glycan, we detected the beta1-3 galactosyltransferase activity in membrane fraction prepared from honeybee cephalic portions. This result indicates that honeybee expresses a unique beta1-3 galactosyltransferase involved in biosynthesis of the unusual N-glycan containing a tumor related antigen in the hypopharyngeal gland.

Precursors of 2‐aminobutanoic acid (2‐ABA), found in the incubation medium of mixed rumen ciliate protozoa, were examined with washed or starved bacteria‐free ciliates. Threonine and methionine strongly stimulated the formation of 2‐ABA. Formation of 2‐ABA by direct conversion of threonine and dethiomethylation of methionine was confirmed by radiotracer experiments with [U‐14C]L‐threonine and [carboxyl‐14C] and [methyl‐14C]L‐methionine.