Genikhovich Grigory, Kürn Ulrich, Hemmrich Georg, Bosch Thomas C G
Zoological Institute, Christian-Albrechts University of Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
Dev Biol. 2006 Jan 15;289(2):466-81. doi: 10.1016/j.ydbio.2005.10.028. Epub 2005 Dec 9.
Hydra's remarkable capacity to regenerate, to proliferate asexually by budding, and to form a pattern de novo from aggregates allows studying complex cellular and molecular processes typical for embryonic development. The underlying assumption is that patterning in adult hydra tissue relies on factors and genes which are active also during early embryogenesis. Previously, we reported that in Hydra the timing of expression of conserved regulatory genes, known to be involved in adult patterning, differs greatly in adults and embryos (Fröbius, A.C., Genikhovich, G., Kürn, U., Anton-Erxleben, F. and Bosch, T.C.G., 2003. Expression of developmental genes during early embryogenesis of Hydra. Dev. Genes Evol. 213, 445-455). Here, we describe an unbiased screening strategy to identify genes that are relevant to Hydra vulgaris embryogenesis. The approach yielded two sets of differentially expressed genes: one set was expressed exclusively or nearly exclusively in the embryos, while the second set was upregulated in embryos in comparison to adult polyps. Many of the genes identified in hydra embryos had no matches in the database. Among the conserved genes upregulated in embryos is the Hydra orthologue of Embryonic Ectoderm Development (HyEED). The expression pattern of HyEED in developing embryos suggests that interstitial stem cells in Hydra originate in the endoderm. Importantly, the observations uncover previously unknown differences in genes expressed by embryos and polyps and indicate that not only the timing of expression of developmental genes but also the genetic context is different in Hydra embryos compared to adults.
水螅具有非凡的再生能力、通过出芽进行无性繁殖的能力以及从聚集体重新形成模式的能力，这使得研究胚胎发育中典型的复杂细胞和分子过程成为可能。其潜在假设是，成年水螅组织中的模式形成依赖于在胚胎早期发育过程中也活跃的因子和基因。此前，我们报道过水螅中已知参与成年模式形成的保守调控基因的表达时间在成体和胚胎中差异很大（弗罗比乌斯，A.C.，格尼霍维奇，G.，库尔恩，U.，安东 - 埃尔克斯勒本，F. 和博施，T.C.G.，2003年。水螅早期胚胎发育过程中发育基因的表达。《发育基因与进化》213，445 - 455）。在此，我们描述了一种无偏向性的筛选策略，以鉴定与普通水螅胚胎发育相关的基因。该方法产生了两组差异表达基因：一组仅在胚胎中表达或几乎仅在胚胎中表达，而第二组与成年息肉相比在胚胎中上调。在水螅胚胎中鉴定出的许多基因在数据库中没有匹配项。在胚胎中上调的保守基因中有胚胎外胚层发育（HyEED）的水螅直系同源物。HyEED在发育胚胎中的表达模式表明，水螅中的间质干细胞起源于内胚层。重要的是，这些观察结果揭示了胚胎和息肉所表达基因中以前未知的差异，并表明与成体相比，水螅胚胎中不仅发育基因的表达时间不同，而且基因背景也不同。
