Biology subjects

Huisken, J.

Publications and source records attributed to Huisken, J..

8 recordsLinked to original sources

bioRxiv2018

Endothelial cells form transient Notch-dependent NO-containing cystic structures during zebrafish cerebrovascular development

Endothelial cell behaviour during blood vessel formation is highly complex and dynamic. Transgenic zebrafish have provided many new insights into these processes, due to their ability to provide detailed in vivo imaging.\n\nWe here report a previously undescribed endothelial cell behaviour during zebrafish embryonic development. Endothelial cells of the cerebral vessels of 3-5d post fertilisation embryos extruded large membranous spherical structures. These were only found on the cerebral vessels, and did not detach from the parent vessel, instead regressing back into the endothelial cell. These structures did not communicate with the vessel lumen, exhibited periodic oscillations in size and shape, and were enriched with filamentous actin at their neck. Due to their unknown nature and spherical appearance we termed these structures kugeln (German for sphere).\n\nPharmacological inhibition of vascular endothelial growth factor (VEGF) signalling significantly increased kugel number while Notch inhibition significantly reduced both kugel number and diameter. Kugeln contain little cytoplasm, but are highly positive for nitric oxide (NO) reactivity, suggesting they represent a novel NO containing organelle specific to the cerebral vessels.

developmental biology↗

bioRxiv2018

Neuromesodermal Progenitors are a Conserved Source of Spinal Cord with Divergent Growth Dynamics

During gastrulation, embryonic cells become specified into distinct germ layers. In mouse, this continues throughout somitogenesis from a population of bipotent stem cells called neuromesodermal progenitors (NMps). However, the degree self-renewal is associated with NMps in the fast-developing zebrafish embryo is unclear. With a genetic clone tracing method, we labelled early embryonic progenitors and find a strong clonal similarity between spinal cord and mesoderm tissues. We then followed individual cell lineages by light-sheet imaging and reveal a common neuromesodermal lineage contribution to a subset of spinal cord tissue across the anterior-posterior body axis. An initial population subdivides at mid gastrula stages and is directly allocated to neural and mesodermal compartments during gastrulation. A second population in the tailbud undergoes delayed allocation to contribute to the neural and mesodermal compartment only at late somitogenesis. We suggest that NMps undergo vastly different rates of differentiation and growth in a species-specific manner.

developmental biology↗

bioRxiv2018

A conserved regulatory program drives emergence of the lateral plate mesoderm

Cardiovascular lineages develop together with kidney, smooth muscle, and limb connective tissue progenitors from the lateral plate mesoderm (LPM). How the LPM initially emerges and how its downstream fates are molecularly interconnected remain unknown. Here, we isolated a pan-LPM enhancer in the zebrafish draculin (drl) gene that provides specific LPM reporter activity from early gastrulation. In toto live imaging and lineage tracing of drl-based reporters captured the dynamic LPM emergence as lineage-restricted mesendoderm field. The drl pan-LPM enhancer responds to the transcription factors EomesoderminA, FoxH1, and MixL1 that combined with Smad activity drive LPM emergence. We uncovered specific drl reporter activity in LPM-corresponding territories of several chordates including chicken, axolotl, lamprey, Ciona, and amphioxus, revealing a universal upstream LPM program. Altogether, our work provides a mechanistic framework for LPM emergence as defined progenitor field, possibly representing an ancient mesodermal cell state that predates the primordial vertebrate embryo.

developmental biology↗

bioRxiv2017

Continuous addition of progenitors forms the cardiac ventricle in zebrafish

The vertebrate heart develops from several progenitor lineages. After early-differentiating first heart field (FHF) progenitors form the linear heart tube, late-differentiating second heart field (SHF) progenitors extend atrium, ventricle, and form the inflow and outflow tracts (IFT/OFT). However, the position and migration of late-differentiating progenitors during heart formation remains unclear. Here, we tracked zebrafish heart development using transgenics based on the cardiopharyngeal transcription factor gene tbx1. Live-imaging uncovered a tbx1 reporter-expressing cell sheath that from anterior lateral plate mesoderm continuously disseminates towards the forming heart tube. High-speed imaging and optogenetic lineage tracing corroborated that the zebrafish ventricle forms through continuous addition from the undifferentiated progenitor sheath followed by late-phase accrual of the bulbus arteriosus (BA). FGF inhibition during sheath migration reduced ventricle size and abolished BA formation, refining the window of FGF action during OFT formation. Our findings consolidate previous end-point analyses and establish zebrafish ventricle formation as a continuous process.

developmental biology↗

bioRxiv2017

Continuous high-resolution in vivo imaging reveals tumor-specific dissemination in an embryonic zebrafish xenograft model

Mechanisms mediating tumor metastasis are crucial for diagnostic and therapeutic targeting. Here, we take advantage of a transparent embryonic zebrafish xenograft model (eZXM) to visualize and track injected human leukemic and breast cancer cells in real time using selective plane illumination microscopy (SPIM) for up to 30 hours. Injected cells exhibited disease-specific patterns of intravascular distribution with leukemic cells moving faster than breast cancer cells. While breast cancer cells predominantly adhered to nearby regions, about 30% invaded the avascularized tissue, reminiscent of their metastatic phenotype. Survival of the injected tumor cells was partly inhibited by the cellular innate immune system of the recipient embryos and leukemic cell dissemination was effectively inhibited by pharmacological ROCK1 blockade. These observations, and the ability to image several embryos simultaneously, support the use of eZXM and SPIM imaging as a functional screening platform to identify compounds that restricts cancer cell spread and invasion.

cancer biology↗

bioRxiv2017

Dynamic, non-contact 3D sample rotation for microscopy

In vivo imaging of growing and developing samples requires a dynamic adaptation of the sample orientation to continuously achieve optimal performance. Here, we present how, after the injection of magnetic beads, a sample can be freely positioned by applying a magnetic field. We demonstrate its performance for zebrafish on an epi-fluorescence microscope and on a light sheet system for superior multi-view acquisition.

bioengineering↗

bioRxiv2017

Pan-embryo cell dynamics of germlayer formation in zebrafish

Cell movements are coordinated across spatio-temporal scales to achieve precise positioning of organs during vertebrate gastrulation. In zebrafish, mechanisms governing such morphogenetic movements have so far only been studied within a local region or a single germlayer. Here, we present pan-embryo analyses of fate specification and dynamics of all three germlayers simultaneously within a gastrulating embryo, showing that cell movement characteristics are predominantly determined by its position within the embryo, independent of its germlayer identity. The spatially confined fate specification establishes a distinct distribution of cells in each germlayer during early gastrulation. The differences in the initial distribution are subsequently amplified by a unique global movement, which organizes the organ precursors along the embryonic body axis, giving rise to the blueprint of organ formation.

developmental biology↗

bioRxiv2017

Cell-Accurate Optical Mapping Across The Entire Developing Heart

Organogenesis depends on orchestrated interactions between individual cells and morphogenically relevant cues at the tissue level. This is true for the heart, whose function critically relies on well-ordered communication between neighbouring cells, which is established and fine-tuned during development. For an integrated understanding of the development of structure and function, we need to move from isolated snap-shot observations of either microscopic or macroscopic parameters to simultaneous and, ideally continuous, cell-to-organ scale imaging. We introduce cell-accurate three-dimensional Ca2+-mapping of all cells in the entire heart during the looping stage in live embryonic zebrafish, using high-speed light sheet microscopy and tailored image processing and analysis. We show how myocardial region-specific heterogeneity in cell function emerges during early development and how structural patterning goes hand-in-hand with functional maturation of the entire heart. Our method opens the way to systematic, scale-bridging, in vivo studies of vertebrate organogenesis by cell-accurate structure-function mapping across entire organs.

biophysics↗