Kwek Joly H L, Iongh Robbert De, Digby Matthew R, Renfree Marilyn B, Nicholas Kevin R, Familari Mary
Department of Zoology, The University of Melbourne, Vic., Australia.
Mech Dev. 2009 May-Jun;126(5-6):449-63. doi: 10.1016/j.mod.2009.01.003. Epub 2009 Jan 23.
There are two phases of fore-stomach development during the first 200 days of pouch life in tammar wallaby. For the first 170 days, the mucosa displays an immature gastric glandular phenotype that changes to a cardia glandular phenotype, which remains for the rest of the animal's life. During this 200-day period after birth, the pouch young (PY) is dependent on maternal milk, which progressively changes in composition. We showed previously that PY cross-fostered to host mothers at a later stage of lactation accelerated development. In this study, we investigated whether cross-fostering and exposure to late lactation stage milk affected the transition to cardia glandular phenotype. In fostered PY fore-stomach, there was increased apoptosis, but no change in cell proliferation. The parietal cell population was significantly reduced, and expression of gastric glandular phenotype marker genes (ATP4A, GKN2, GHRL and NDRG2) was down-regulated, suggesting down-regulation of gastric phenotype in fostered PY fore-stomach. The expression of cardia glandular phenotype genes (MUC4, KRT20, CSTB, ITLN2 and LPLUNC1) was not changed in fostered PY. These data suggest that fore-stomach maturation proceeds via two temporally distinct processes: down-regulation of gastric glandular phenotype and initiation of cardia glandular phenotype. In fostered PY, these two processes appear uncoupled, as gastric glandular phenotype was down-regulated but cardia glandular phenotype was not initiated. We propose that milk from later stages of lactation and/or herbage consumed by the PY may play independent roles in regulating these two processes.
在帚尾袋貂育儿袋生活的前200天里，前胃发育有两个阶段。在最初的170天里，黏膜呈现出不成熟的胃腺表型，之后转变为贲门腺表型，并在动物的余生中保持。在出生后的这200天里，育儿袋幼崽（PY）依赖母乳，母乳的成分会逐渐变化。我们之前表明，在哺乳后期被寄养到宿主母亲处的PY发育加速。在本研究中，我们调查了寄养以及接触哺乳后期的乳汁是否会影响向贲门腺表型的转变。在寄养的PY前胃中，细胞凋亡增加，但细胞增殖没有变化。壁细胞数量显著减少，胃腺表型标记基因（ATP4A、GKN2、GHRL和NDRG2）的表达下调，表明寄养的PY前胃中胃表型下调。寄养的PY中贲门腺表型基因（MUC4、KRT20、CSTB、ITLN2和LPLUNC1）的表达没有变化。这些数据表明，前胃成熟通过两个在时间上不同的过程进行：胃腺表型下调和贲门腺表型启动。在寄养的PY中，这两个过程似乎是分离的，因为胃腺表型下调但贲门腺表型没有启动。我们认为，哺乳后期的乳汁和/或PY食用的草料可能在调节这两个过程中发挥独立作用。
