Evolution

Adapting to the Young

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Science  10 Jul 2009:
Vol. 325, Issue 5937, pp. 127
DOI: 10.1126/science.325_127a
CREDIT: THAN ET AL., PROC. NATL. ACAD. SCI. U.S.A. 106, 9731 (2009)

Some human pregnancies result in deleterious immune interactions between the mother and fetus, which are sometimes attributed to genetic incompatibilities between placental cells and the mother's blood. One such interaction is mediated by galectin (above left), a carbohydrate-binding protein that recognizes cell surface molecules on leukocytes. Than et al. find that a cluster of galectin genes on human chromosome 19 shows evidence of having evolved via multiple duplications and rearrangements, and three of these genes are highly expressed at the maternal-fetal interface. This cluster of galectins is present and expressed in the great apes, and in Old World and New World monkeys, but is not found in prosimians (lemurs) or nonprimates. Furthermore, lineage-specific loss and gain of specific gene copies were identified within the monkey and ape clusters, and functional data indicate that differential sugar binding has evolved within the gene cluster. Overall, these findings suggest that the evolution of the long gestational period of humans may have been accompanied by changes in genes involved in maternal-fetal tolerance.

Proc. Natl. Acad. Sci. U.S.A. 106, 9731 (2009).

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