Structural study on snail galactans from the genus Biomphalaria.

Abstract

Galactans from albumen glands and from freshly collected egg masses of intermediary hosts of bilharzia in Brazil (Biomphalaria glabrata, Biomphalaria tenagophila and Biomphalaria straminea) were investigated. All these galactans had D-galactopyranose characterized as the sole sugar component. No evidence was found for the presence of L-galactopyranose in these polymers, using specific enzymes. Methanolysis of the methylated galactans and periodate oxidation data indicated a multibranched structure for these galactans. Yields of O-methyl sugars showed a equimolecular proportion of non-reducing end groups and disubstituted residues linked through positions 3 and 6 and a predominance of /?-(l ->3)-over /?-(l ->6)-linkages. In view of the structural identity presently observed in the galactans from all our sources, as compared to the distinctive structure proposed for the galactan after five days of egg masses laying [M. Iacomini et al, Arq. Biol. Tecnol, 23, 329 (1980)], it is inferred that the enzymic system for galactan degradation is still inactive in freshly collected egg masses.l\ Galactans from snails were isolated as early Moretto et al.S) 'based on oxidative degraas 1885,1* but structural studies were madejust dation results, proposed another structural recently. conception for the albumen gland galactans of O'Colla2) applied the Barry degradation to Megalobulimus genus, as being a multibranchthe albumen gland galactan from Helix po-ed structure containing also linear segments matia and showed that the alternative struc-ofj8-(l.->3)-or j8-(l ->6)-linkages. This kind of tures proposed by Bell and Baldwin3] for this model was in accordance with the methylation polymer were an over-simplification and that data previously obtained for S. oblongus the galactan had a dichotomously branched galactan.5) structure, consisting of alternate j8-(l->3)-Bell and Baldwin3) also verified that the and /?-(l-^-linkages. Correa et al.,4) using galactan from H. pomatia confdimd n-and lthe same kind of degradation, suggested a galactose residues in a 6:1 ratio. Correa et similar structure for the albumen gland galac-al.4) also suggested that galactose residues not tan ofBiomphalaria glabrata. Further, Duarte susceptible to the action of D-galactose oxiand Jones5} showed that the methylation data dase could be a evidence of the L-isomer in the of Strophocheilus oblongus albumen gland ga-galactan of B. glabrata. lactan were not completely compatible with a On the other hand, the polymer isolated dichotomously branched structure. Recently, from egg masses of Ampullarius sp. differedSegura and Duarte,6) Iacomini et al.1] and from the albumen gland polysaccharides al-

Arabinogalactan-Proteins in The Evolution of Gravity Resistance in Land Plants

“…We have reported the structure of a β-galactan with β-1,3;1,6-galactan as the backbone from Prototheca zopfii, which belongs to the Chlorellaceae family (Okemoto et al, 2003). Moreover, β-1,3;1,6-galactan has been found in a snail and a mammal (Roy and Glaudemans, 1978;Iacomini et al, 1981). It thus seems that the origin of AG is relatively old.…”

Variation of acharan sulfate and monosaccharide composition and analysis of neutral N-glycans in African giant snail (Achatina fulica)

“…Snail galactans from Biomphalaria , from albumin glands and freshly collected eggs, are mainly composed of d -galactopyranose. Biomphalaria galactans contain more β(1–3) linkages than β(1–6) linkages [22]. …”