Intestinal Glycosidase Activities in one Adult and two Suckling Echidnas: Absence of a Neutral Lactase (b-D-Galactosidase).

Stewart, Ivan; Messer, Michael; Walcott, P J; Gadiel, P A; Griffiths, Mervyn

doi:10.1071/bi9830139

Cited by 16 publications

(4 citation statements)

References 23 publications

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“…With respect to monotremes, it has been shown that small intestinal neutral lactase activity was entirely absent but, as in marsupials, various acid glycosidases including b-galactosidase, a-L-fucosidase and neuraminidase could be detected in the small intestine of the suckling echidna. These results were consistent with the concept that the oligosaccharides of echidna milk (mainly sialyl and fucosyllactoses) are digested by lysosomal enzymes contained within the enterocytes of the small intestine (Stewart et al, 1983). …”

Section: Urashima Fukuda and Messer Core Units And Lewis X (Galsupporting

confidence: 91%

Evolution of milk oligosaccharides and lactose: a hypothesis

Urashima

Fukuda

Messer

2012

Animal

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Mammalian milk or colostrum contains up to 10% of carbohydrate, of which free lactose usually constitutes more than 80%. Lactose is synthesized within lactating mammary glands from uridine diphosphate galactose (UDP-Gal) and glucose by a transgalactosylation catalysed by a complex of b4-galactosyltransferase and a-lactalbumin (a-LA). a-LA is believed to have evolved from C-type lysozyme. Mammalian milk or colostrum usually contains a variety of oligosaccharides in addition to free lactose. Each oligosaccharide has a lactose unit at its reducing end; this unit acts as a precursor that is essential for its biosynthesis. It is generally believed that milk oligosaccharides act as prebiotics and also as receptor analogues that act as anti-infection factors. We propose the following hypothesis. The proto-lacteal secretions of the primitive mammary glands of the common ancestor of mammals contained fat and protein including lysozyme, but no lactose or oligosaccharides because of the absence of a-LA. When a-LA first appeared as a result of its evolution from lysozyme, its content within the lactating mammary glands was low and lactose was therefore synthesized at a slow rate. Because of the presence of glycosyltransferases, almost all of the nascent lactose was utilized for the biosynthesis of oligosaccharides. The predominant saccharides in the proto-lacteal secretions or primitive milk produced by this common ancestor were therefore oligosaccharides rather than free lactose. Subsequent to this initial period, the oligosaccharides began to serve as anti-infection factors. They were then recruited as a significant energy source for the neonate, which was achieved by an increase in the synthesis of a-LA. This produced a concomitant increase in the concentration of lactose in the milk, and lactose therefore became an important energy source for most eutherians, whereas oligosaccharides continued to serve mainly as anti-microbial agents. Lactose, in addition, began to act as an osmoregulatory molecule, controlling the milk volume. Studies on the chemical structures of the milk oligosaccharides of a variety of mammalian species suggest that human milk or colostrum is unique in that oligosaccharides containing lacto-N-biose I (LNB) (Gal(b1 -3)GlcNAc, type I) predominate over those containing N-acetyllactosamine (Gal(b1 -4)GlcNAc, type II), whereas in other species only type II oligosaccharides are found or else they predominate over type I oligosaccharides. It can be hypothesized that this feature may have a selective advantage in that it may promote the growth of beneficial colonic bacteria, Bifidobacteria, in the human infant colon.Keywords: lactose, milk oligosaccharides, a-lactalbumin, lysozyme, lactation, prebiotics, bifidobacteria Implications Eutherian mammals' milk or colostrum usually contains small amounts of oligosaccharides and lactose, the dominant carbohydrate. Lactose acts as a main energy source for neonates, whereas milk oligosaccharides are believed to act as prebiotics that stimulate the growth of benefici...

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Section: Urashima Fukuda and Messer Core Units And Lewis X (Galsupporting

confidence: 91%

Evolution of milk oligosaccharides and lactose: a hypothesis

Urashima

Fukuda

Messer

2012

Animal

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“…The predominance of lactose in giant anteater milk suggests that the neonate uses lactose as a significant energy source and that the microvilli of the small intestinal mucosa therefore contain an active neutral lactase capable of digesting this disaccharide. It can also be hypothesized that this enzyme was acquired by the ancestral therians prior to the divergence of the marsupials, because, although it has been shown to be absent in monotremes (Stewart et al . 1983) it is present in possums and other non‐macropod marsupials (Messer et al .…”

Section: Discussionmentioning

confidence: 99%

Structural determination of the oligosaccharides in the milk of a giant anteater (Myrmecophaga tridatyla)

Urashima¹,

Komoda

Asakuma

et al. 2008

Animal Science Journal

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There appears to be strong evidence supporting four major clades of placental mammals: (i) Afrotheria; (ii) Xenarthea; (iii) Euarchontoglires; and (iv) Laurasiathera. This is the first study in which the carbohydrates have been analyzed in the milks of Xenarthea. Our aim was to clarify whether the saccharides of giant anteater milk resemble those of other eutherian species, especially of the Asian elephant, which is one of the Afrotherea. We found that lactose is a dominant saccharide in this milk, as it is in that of most eutherians, and that the milk contains smaller amounts of oligosaccharides, whose structures were determined as Gal(α1‐3)Gal(β1‐4)Glc (isoglobotriose), Neu5Ac(α2‐6)Gal(β1‐4)Glc (6'‐N‐acetylneuraminyllactose), Neu5Gc(α2‐6)Gal(β1‐4)Glc (6'‐N‐glycolylneuraminyllactose), Neu5Ac(α2‐6)Gal(β1‐4)GlcNAc(β1‐3)Gal(β1‐4)Glc (LST c) and Neu5Gc(α2‐6)Gal(β1‐4)GlcNAc(β1‐3)Gal(β1‐4)Glc. This pattern of milk carbohydrates is rather close to that of the milks of other eutherian species. It is notable that the milk contained oligosaccharides with Neu5Gc residues but no oligosaccharides containing α(2‐3) linked Neu5Ac residues such as Neu5Ac(α2‐3)Gal(β1‐4)Glc.

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“…It has been found that the activity of small intestinal lactase is lacking in the suckling neonates of monotremes ( Stewart et al, 1983 ) and Macropodidae marsupials ( Walcott and Messer, 1980 ; Crisp et al, 1987 ; Messer et al, 1989 ), including wallabies and kangaroos. Based on the histochemical observations of the small intestine of the suckling echidna and tammar wallaby, it has been concluded that the milk oligosaccharides are transported by pinocytosis or endocytosis into the small intestinal cells and then enclosed in the supranuclear vacuoles to be moved to the lysosome.…”

Section: Small Intestinal Digestion Of Milk Oligosaccharides In Suckl...mentioning

confidence: 99%