Yn. Malykh et al., The presence of N-acetylneuraminic acid in Malpighian tubules of larvae ofthe cicada Philaenus spumarius, GLYCOCON J, 16(11), 1999, pp. 731-739
Sialic acid-containing glycoconjugates are generally considered to be uniqu
e to the deuterostomes, a lineage of the animal kingdom which includes anim
als from the echinoderms up to the vertebrates. There are, however, two iso
lated reports of sialic acid occurring in the insect species Drosophila mel
anogaster and Galleria mellonella. Since insects are classified as protosto
mes, these findings call previous assumption on the phylogenetic distributi
on and thus on the evolution of sialic acids into question. Here, we report
the occurrence of N-acetylneuraminic acid (Neu5Ac) in larvae of the cicada
Philaenus spumarius. Cytochemical analysis of larval sections with lectins
from Sambucus nigra and Limax flavus suggested the presence of sialic acid
s in the concrement vacuoles of the Malpighian tubules. The monoclonal anti
body MAb 735, which is specific for polysialic acid, labelled the same stru
ctures. A chemical analysis performed by HPLC of fluorescent derivatives of
sialic acids and by GLC-MS provided sound evidence for the presence of Neu
5Ac in the Philaenus spumarius larvae. These data suggest that in this cica
da Neu5Ac occurs in alpha 2,8-linked polysialic acid structures and in alph
a 2,6-linkages. The results provide further evidence for the existence of s
ialic acids in insects and in linkages known to occur in glycoconjugates of
deuterostomate origin.