![]() ![]() Indicative of their altricial state, newborn marsupials are unable to initiate endogenous immune responses until they are at least a week of age. Therefore, much of the development that occurrs in prenatal humans and other placental mammals appears to be postnatal in marsupials, making marsupials unique models of early immune system development. The developmental state of the newborn marsupial immune system has been equated to that of a human embryo at the eighth to tenth week of gestation or a mouse or rat at the tenth day of gestation –. Marsupials, such as opossums and kangaroos, are born in an extreme altricial state compared to any placental mammal. The marsupials are one of three living lineages of mammals (placentals, marsupials, and monotremes ) that differ substantially in their state of development at birth. Whether a species is considered altricial or precocial at birth is, of course, a relative distinction. A newborn mouse, for example, is much less developed than the more immunologically precocious cow or pig. The degree of immunological competence of newborn animals varies considerably between mammalian species. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. P20 GM103452-09 from the Institutional Development Award program and a National Science Foundation award IOS-0641382. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: This research was supported in part the National Institutes of Health grant no. Received: JAccepted: AugPublished: September 24, 2012Ĭopyright: © Wang et al. Newborn light chain diversity is, from the start, comparable to that of the adult, consistent with an earlier hypothesis that light chains contribute extensively to antibody diversity in this species.Ĭitation: Wang X, Sharp AR, Miller RD (2012) Early Postnatal B Cell Ontogeny and Antibody Repertoire Maturation in the Opossum, Monodelphis domestica. The diversity of early B cell IgH chains is limited, as has been seen in fetal humans and mice, but lacks bias in the gene segments used to encode the variable domains. The predicted timing of the earliest appearance of mature B cells and completion of gene rearrangements is consistent with previous analyses on the timing of endogenous antibody responses in newborn marsupials. Transcription of the Ig light chains was not detected until postnatal day 7 at the earliest. Transcription of CD79a and CD79b was detected in embryonic tissue prior to birth, while immunoglobulin heavy chain locus transcription was not detected until the first postnatal 24 hours. The results support the initiation of B cell development late in gestation and progressing into the first two weeks of postnatal life. Postnatal B cell ontogeny and diversity was investigated in a model marsupial species, the gray short-tailed opossum, Monodelphis domestica. Marsupials are a lineage of mammals noted for giving birth to highly altricial young, which complete much of their “fetal” development externally attached to a teat. ![]()
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