Pregastrular morphogenesis in Xenopus

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。该项目的主要目的是研究一类新发现的膜性突起在非洲爪哇早期卵裂期胚胎中连接卵裂球的发育作用。时间推移共聚焦显微镜对表达膜拴系荧光蛋白的活的手术开放胚胎进行了观察，意外地发现数百个极长、稳定的丝状足细胞遍及整个胚泡，相互连接着相距多达300微米的胚泡。大多数卵裂球似乎同时相互连接，并通过这些长的丝状足细胞与多达六个相邻和不相邻的细胞长期接触。这些突起充满了f-肌动蛋白，小的膜性小泡在其中双向移位。在512细胞期附近，大多数长的丝状孢子附着在附近的卵裂球表面并泡化，产生一簇簇小的结合在膜上的细胞质颗粒。这些显著结构的出现时间和分布表明，可能通过母体成分的矢量运输或通过卵裂球-卵裂球的通讯，在早期胚胎模式中发挥了直接作用。这个项目的目的是通过以下问题来探索这一假说：1)穿越丝状足突的空间模式是否相对于初级胚轴有偏见；2)背腹模式的早期扰动是否改变了它们的部署或功能。智力优势：这些活动探索了一种新的物理途径的潜力，用于在早期卵裂球之间传输母体形态原或信号，因此代表了发育生物学中一个长期存在的问题的新方面。更广泛的影响：PI致力于指导学生、教师和来访的科学家的项目。这里描述的实验将为研究生、本科生和其他对早期发展感兴趣的人提供有用的培训基础。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The main objective of this project is to investigate the developmental role of a newly discovered class of membranous protrusions interconnecting blastomeres of early, cleavage-stage Xenopus laevis embryos. Time lapse confocal microscopy of live, surgically opened embryos expressing a membrane-tethered fluorescent protein unexpectedly reveals hundreds of extremely long, stable filopodia traversing the entire volume of the blastocoel, interconnecting blastomeres separated by as much as 300 microns. Most blastomeres appear to be simultaneously interconnected and in long-term contact with as many as half a dozen adjacent and nonadjacent cells via these long filopodia. These processes are filled with f-actin, and small membranous blebs translocate bidirectionally within them. Near the 512-cell stage, most of the long filopodia settle onto nearby blastomere surfaces and vesiculate, producing clusters of small membrane-bound, cytoplasm-bearing particles. The time of appearance and distribution of these remarkable structures suggest a direct role in early embryonic patterning, perhaps via the vectorial transport of maternal components or via blastomere-blastomere communication. The aims of this project are to explore this hypothesis by asking 1) whether the spatial pattern of traversing filopodia is biased with respect to the primary embryonic axes; 2) whether early perturbation of dorsal-ventral patterning alters their deployment or function. Intellectual merit: These activities explore the potential of a novel physical pathway for transporting maternal morphogens or signaling between early blastomeres, and thus represents a new facet on a problem of long standing in developmental biology. Broader impact: The PI is committed to the mentoring of projects by students, teachers, and visiting scientists. The experiments described here will provide a useful training ground for graduate students, undergraduates, and others interested in early development.