细胞功能测定

Signaling by the wingless pathway has been shown to govern numerous developmental processes. Much of our current understanding of wingless signaling mechanisms comes from studies conducted in Drosophila melanogaster, which offers superior experimental tractability for ge ...

Wnt signaling has been demonstrated to regulate diverse cell processes throughout the development of the Caenorhabditis elegans embryo. This chapter describes methods that have been used to investigate some of these Wnt-dependent processes: endoderm specification, mitotic s ...

Wnts play a central role in the development of many cells and tissue types in all species studied to date. Like many other extracellular signaling pathways, secreted Wnt proteins are involved in many different processes; in C. elegans these include: cell proliferation, differentiation, ce ...

Cnidarians are simple metazoans with only two body layers and a primitive nervous system. They are famous for their nearly indefinite regeneration capacity. Recent work has identified most of the Wnt subfamilies and Wnt antagonists known from vertebrates in this basal animal model. Wnt si ...

The anthozoan cnidarian Nematostella vectensis has emerged as a key model system for evolutionary developmental biology studies, and this animal' usefulness will grow with the recent sequencing of its genome. In particular, work done in Nematostella is providing insight into the role of ...

Cnidarians are an ancient group of animals at the base of metazoan evolution. They exhibit a simple body plan with only one well-defined body axis and a small number of cell types. Cnidarians are also well known for their enormous regeneration capacity. Recent work in the freshwater polyp Hydra and in t ...

GSK-3 activity mediates cAMP repression of stalk induction of cells in low-density monolayer culture. The lower the GSK-3 activity the greater the percentage of stalk cells formed. This protocol describes a robust and quantitative method utilizing an adapted stalk cell monolayer assay ...

Monitoring the spatial distribution of prespore and pstB cell types is a sensitive method to monitor GSK-3 and Aar activity during Dictyostelium development. Cell-specific expression of lacZ marker genes can be readily detected using enzymatic cleavage of the substrate X-gal. This pr ...

Although Wnt signaling is ubiquitous within the animal phylogenetic group, it is unclear how it evolved. Genes related to the components of Wnt pathway are found in other eukaryotes and one of the most studied of these non-metazoan organisms is the social amoeba Dictyostelium discoideum. This ...

Wnt proteins mediate the transduction of at least three major signaling pathways that play central roles in many early and late developmental decisions. They control diverse cellular behaviors, such as cell fate decisions, proliferation, and migration, and are involved in many import ...

Formation of tissue boundaries can be studied in a simple, inexpensive system, the Xenopus gastrula. Here, the internalized mesoderm and endoderm are separated from the ectodermal blastocoel roof by Brachet ' s cleft. Non-canonical Wnt signaling mediated by the Wnt receptor, Xfz-7, is esse ...

Non-canonical Wnt signaling is an important regulator of gastrulation in Xenopus. In particular, it has been implicated in the control of convergent extension movements. Convergent extension in the gas-trula occurs primarily in the dorsal tissue of the marginal zone, and explants of this ...

The easy accessibility, distinctive features of early cleavage stage embryos and simple manipulation methods make Xenopusembryos an ideal model organism to study gene function and deciphering signaling pathways. For many years, investigators have analyzed putative dorsal ...

The Wnt signaling cascades are regulatory modules which are involved in embryonic patterning, cell differentiation, morphogenesis, and diseases (1, 2). The Wnt pathways are activated when secreted Wnt ligands interact with 7-trans-membrane receptors of the Frizzled (Fz) family. Sp ...

Xenopus laevis has for many years been successfully used to study Wnt signaling during early development. However, because loss of function and gain of function experiments generally involve injecting RNA, DNA, or morpholinos into early embryos (1- to 32-cell), major phenotypes are often o ...

Early development in Xenopus laevis is controlled by maternal gene products synthesized during oogen-esis. The dorsal/ventral and anterior/posterior axes are established as a result of canonical Wnt signaling activity. The functions of maternal genes in embryonic development ...

Xenopus embryos are particularly suited for functional experiments to investigate vertebrate embryonic development. Due to the large size of embryos and their development outside of the mother organism, they are very accessible, easy to manipulate, and allow for immediate observa ...

The terminal chromatin structures at the ends of eukaryotic chromosomes, the telomeres, are a focus of intensive research due to their importance for the maintenance of chromosome integrity. Their shortening due to incomplete replication functions as a molecular clock counting the n ...

Fluorescence tagging of genomic sites through the use of bacterial operator/repressor systems combined with fluorescent proteins permits high-resolution analysis of interphase chromosomes in living cells. This technique has been used to study interphase chromosome arra ...

Fluorescence in situ hybridization (FISH) of specific DNA probes has become a widely used technique mostly for chromosome analysis and for studies of the chromosomal location of specific DNA segments in metaphase preparations as well as in interphase nuclei. FISH on 3D-preserved nuclei ...