In vivo imaging and quantitative analysis of zebrafish embryos by digital holographic microscopy.

Digital holographic microscopy (DHM) has been applied extensively to in vitro studies of different living cells. In this paper, we present a novel application of an off-axis DHM system to in vivo study of the development of zebrafish embryos. Even with low magnification microscope objectives, the morphological structures and individual cell types inside developing zebrafish embryos can be clearly observed from reconstructed amplitude images.

Zebrafish eve1 regulates the lateral and ventral fates of mesodermal progenitor cells at the onset of gastrulation.

Zebrafish eve1, a member of the even-skipped related gene family, is expressed initially in the animal pole of late blastula embryo and subsequently restricted to the ventral mesoderm of the gastrula embryo under the signaling control of bone morphogenetic protein (Bmp). Overexpression of eve1 in embryos results in similar ventralized phenotypes to that seen in embryos overexpressing Bmp, suggesting that Eve1 acts downstream of the Bmp signaling pathway to regulate the fate of mesodermal progenitor cells (MPCs). How eve1 functions in the normal development of MPCs is unknown.

Biocompatibility and biodistribution of surface-enhanced Raman scattering nanoprobes in zebrafish embryos: in vivo and multiplex imaging.

Nanoparticles are increasingly being used to investigate biological processes in various animal models due to their versatile chemical, unique optical, and multifunctional properties. In this report we address the biocompatibility and biodistribution of nanoparticle sensors used for Raman chemical imaging in live zebrafish (Danio rerio) embryos. Surface-enhanced Raman scattering (SERS) nanoprobes (NPs) comprising gold nanoparticles (AuNPs) as enhancing substrate and nonfluorescent Raman labels were synthesized and microinjected into zebrafish embryos at the one-cell stage.

Disruption of zebrafish cyclin G-associated kinase (GAK) function impairs the expression of Notch-dependent genes during neurogenesis and causes defects in neuronal development.

Background: The J-domain-containing protein auxilin, a critical regulator in clathrin-mediated transport, has been implicated in Drosophila Notch signaling. To ask if this role of auxilin is conserved and whether auxilin has additional roles in development, we have investigated the functions of auxilin orthologs in zebrafish.

Results: Like mammals, zebrafish has two distinct auxilin-like molecules, auxilin and cyclin G-associated kinase (GAK), differing in their domain structures and expression patterns.

The regulation of mesodermal progenitor cell commitment to somitogenesis subdivides the zebrafish body musculature into distinct domains.

The vertebrate musculature is produced from a visually uniform population of mesodermal progenitor cells (MPCs) that progressively bud off somites populating the trunk and tail. How the MPCs are regulated to continuously release cells into the presomitic mesoderm throughout somitogenesis is not understood. Using a genetic approach to study the MPCs, we show that a subset of MPCs are set aside very early in zebrafish development, and programmed to cell-autonomously enter the tail domain beginning with the 16th somite.

Visualizing morphogenesis in transgenic zebrafish embryos using BODIPY TR methyl ester dye as a vital counterstain for GFP.

Green fluorescent protein (GFP) technology is rapidly advancing the study of morphogenesis, by allowing researchers to specifically focus on a subset of labeled cells within the living embryo. However, when imaging GFP-labeled cells using confocal microscopy, it is often essential to simultaneously visualize all of the cells in the embryo using dual-channel fluorescence to provide an embryological context for the cells expressing GFP. Although various counterstains are available, part of their fluorescence overlaps with the GFP emission spectra, making it difficult to clearly identify the cells expressing GFP.

Combinatorial gene regulation by Bmp and Wnt in zebrafish posterior mesoderm formation.

Combinatorial signaling is an important mechanism that allows the embryo to utilize overlapping signaling pathways to specify different territories. In zebrafish, the Wnt and Bmp pathways interact to regulate the formation of the posterior body. In order to understand how this works mechanistically, we have identified tbx6 as a posterior mesodermal gene activated by both of these signaling pathways.

HrT is required for cardiovascular development in zebrafish.

The recently identified zebrafish T-box gene hrT is expressed in the developing heart and in the endothelial cells forming the dorsal aorta. Orthologs of hrT are expressed in cardiovascular cells from Drosophila to mouse, suggesting that the function of hrT is evolutionarily conserved. The role of hrT in cardiovascular development, however, has not thus far been determined in any animal model.