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Mesoglea fate in the tentacles and the head region. ( A , B ) Labeled collagen-1 (green) in the head region and the tentacle base 3 hours after injection and 7 days after injection. The label in the tentacle (star) moves to the tip of the tentacle by day 7, the label in the head region (st) remains stationary. ( C ) Position ( y -axis) of the border between labeled and unlabeled tissue of seven individual head grafts over the course of 11 and 13 days ( x -axis). No displacement is observed. Scale bar: 500 m m.
Source publication
Growth and morphogenesis during embryonic development, asexual reproduction and regeneration require extensive remodeling of the extracellular matrix (ECM). We used the simple metazoan Hydra to examine the fate of ECM during tissue morphogenesis and asexual budding. In growing Hydra, epithelial cells constantly move towards the extremities of the a...
Contexts in source publication
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... is displaced toward the tip of the tentacles, but is stationary in the head region Labeled mesoglea in the tentacles was displaced toward the tip of the tentacle (Fig. 4A,B, star). The displacement took about 7 days to move from the base of the tentacle to the tip (n520) as shown in Fig. 4A,B. No differences in label displacement were observed between animals fed daily compared with animals fed every other day (data not shown). Once the labeled mesoglea reached the tip of the tentacle, it shrank in size ...
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... is displaced toward the tip of the tentacles, but is stationary in the head region Labeled mesoglea in the tentacles was displaced toward the tip of the tentacle (Fig. 4A,B, star). The displacement took about 7 days to move from the base of the tentacle to the tip (n520) as shown in Fig. 4A,B. No differences in label displacement were observed between animals fed daily compared with animals fed every other day (data not shown). Once the labeled mesoglea reached the tip of the tentacle, it shrank in size and disappeared (data not shown). Similarly to the situation in the basal disc, we observed fluorescent material in the ...
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... mesoglea in the head region remained stationary (Fig. 4A,B, st) and a sharp border could be observed between the stationary head mesoglea and the mesoglea, which was displaced outward along the tentacle (Fig. 4B, arrowhead). The stationary region included the hypostome of the animal and extended to about 9% body column length: when we grafted heads of labeled donor animals, cut off at 9% (or ...
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... mesoglea in the head region remained stationary (Fig. 4A,B, st) and a sharp border could be observed between the stationary head mesoglea and the mesoglea, which was displaced outward along the tentacle (Fig. 4B, arrowhead). The stationary region included the hypostome of the animal and extended to about 9% body column length: when we grafted heads of labeled donor animals, cut off at 9% (or less) body length, onto gastric columns of non-labeled acceptor animals (or vice versa), the label showed no displacement (Fig. 4C). Grafts at body column position ...
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... outward along the tentacle (Fig. 4B, arrowhead). The stationary region included the hypostome of the animal and extended to about 9% body column length: when we grafted heads of labeled donor animals, cut off at 9% (or less) body length, onto gastric columns of non-labeled acceptor animals (or vice versa), the label showed no displacement (Fig. 4C). Grafts at body column position lower than 9%, however, were subject to displacement (Fig. 2D). Labeled mesoglea within the stationary head region faded without visible lateral displacement, which suggests local ...
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... In the lower peduncle, both epithelial Fig. 7. Mesoglea turnover in different body regions estimated as laminin stability in tissue lysates. Isolated mesoglea samples containing laminin were incubated in tissue lysates from different body regions of the animal as indicated. For head lysate, only the head without tentacle tissue was used (compare Fig. 4C, st). Bud lysate was taken from bud stages 3-5. Samples taken at different time points were analyzed by western blotting using antibodies against laminin and a-tubulin. The a-tubulin is not significantly degraded in any of the lysate samples; the a-tubulin blot shown corresponds to the basal disc lysate. Results of mesoglea and cell ...
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... cells of the tentacle originate in the body column (Fig. 3A-C) (Campbell, 1967b;Hobmayer et al., 1990), whereas the new tentacle mesoglea is made at the base of the tentacle (Fig. 4A,B). Consequently, when cells moved into the tentacles, they appeared to leave the stationary mesoglea in the head region and moved onto newly forming mesoglea at the tentacle base (Fig. 9A,B). Once in the tentacle, ectodermal cells were displaced together with their underlying mesoglea (Fig. 8C,D). A very similar situation could also be ...
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... ectodermal cells were displaced together with their underlying mesoglea (Fig. 8C,D). A very similar situation could also be observed during budding. Numerous cells of both epithelial layers moved from the parent body column into developing buds (Otto and Campbell, 1977a), whereas the amount of recruited mesoglea remained relatively small (Fig. 9C-E, Fig. 4D,E; supplementary material Fig. S3B-E). The area of recruited cells had a diameter approximately 3-4 times larger than the area of recruited ECM (Fig. 9F, ...
Citations
... This proportionate effect was also reflected in the extent of bidirectional flow of both epithelial cells and their underlying ECM. This bidirectional pattern mirrors similar dynamics in Hydra, where continuous tissue and mesoglea movements are part of homeostasis (45,46). In Nematostella, however, such movement is triggered by injury, showing the dynamic nature of the cnidarian mesoglea. ...
The complexity of regeneration extends beyond local wound responses (1,2), eliciting systemic processes that engage the entire organism. However, their functional relevance, and the spatial and temporal orchestration of the underlying molecular processes distant from the injury site remain unknown. Here, we demonstrate that local regeneration in the cnidarian Nematostella vectensis involves a systemic homeostatic response, leading to coordinated whole-body remodeling. Leveraging spatial transcriptomics, endogenous protein tagging, and live imaging, we comprehensively dissect this systemic response at the organismal scale. We identify proteolysis as a critical process driven by both local and systemic upregulation of metalloproteases. We show that metalloproteinase expression levels and activity scale with the extent of tissue loss, leading to proportional long-range movement of tissue and its associated extracellular matrix. Our findings illuminate the adaptive nature of the systematic response in regeneration. We propose that this integrated regenerative mechanism, shifting the system from a steady to a dynamic homeostatic state, allows the organism to cope with a wide range of injuries.
... Hydrated and gel-like tissue structures, such as vacuoles initially containing liquid or the gel-like mesoglea were strongly diminished and/or deformed. In contrast, these same tissue structures appeared full of their natural contents and in their original shapes after HPF and subsequent cryo-preparation (Fig. 4C), compared with in vivo imaging [31]. are routinely separated from potential mass interferences and counted in electron multiplier detectors to permit quantitative measurements of the sample 15 N/ 14 N isotope ratio. ...
Background
The development of nanoscale secondary ion mass spectrometry (NanoSIMS) has revolutionized the study of biological tissues by enabling, e.g., the visualization and quantification of metabolic processes at subcellular length scales. However, the associated sample preparation methods all result in some degree of tissue morphology distortion and loss of soluble compounds. To overcome these limitations an entirely cryogenic sample preparation and imaging workflow is required.
Results
Here, we report the development of a CryoNanoSIMS instrument that can perform isotope imaging of both positive and negative secondary ions from flat block-face surfaces of vitrified biological tissues with a mass- and image resolution comparable to that of a conventional NanoSIMS. This capability is illustrated with nitrogen isotope as well as trace element mapping of freshwater hydrozoan Green Hydra tissue following uptake of ¹⁵N-enriched ammonium.
Conclusion
With a cryo-workflow that includes vitrification by high pressure freezing, cryo-planing of the sample surface, and cryo-SEM imaging, the CryoNanoSIMS enables correlative ultrastructure and isotopic or elemental imaging of biological tissues in their most pristine post-mortem state. This opens new horizons in the study of fundamental processes at the tissue- and (sub)cellular level.
Teaser
CryoNanoSIMS: subcellular mapping of chemical and isotopic compositions of biological tissues in their most pristine post-mortem state.
... [20][21][22] Immunofluorescence labeling of HCol-I revealed that the mesoglea of an evaginating bud showed weaker signals compared to the mother polyp, which was attributed to the thinning of mesoglea in order to accommodate a large number of cells flowing out from the parental Hydra. 23 The thinning of the ECM naturally suggested that rapidly growing buds are softer, but there has been no quantitative study on how tissue morphogenesis of Hydra correlates with the local structural orders and elasticity of ECM during patterning and asexual reproduction. ...
... In fact, t = 2-3 days is the typical time window for freshly detached Hydra polyps to start budding. 36 ECMs of fast-growing buds became thinner with time, 23 resulting in a homogeneous and lowelasticity pattern (type A). Our data indicate that the growth process and maturation of freshly detached buds toward mature, bud-forming polyps are accompanied by the modulation of elasticity patterns in iScience Article Hydra ECM. ...
... Micrometer-scale order of iScience Article mesoglea of an evaginating bud, related to Figure 5) like the one from parental Hydra, which shows good agreement with previous account reporting the thinning of mesoglea during budding. 23 In an in-depth analysis, we determined the nanometer-scale arrangement of ECM proteins using nano-GI-SAXS, which has been used mainly for colloids and polymers. 24,25 As nano-GISAXS enables one to collect the structural information from the beam footprint smaller than a mesoglea, we unraveled that collagen fibers (Hcol-I) take highly asymmetric, distorted hexagonal lattices. ...
The extracellular matrix (ECM) plays crucial roles in animal development and diseases. Here, we report that Wnt/β-catenin signaling induces the ECM remodeling during Hydra axis formation. We determined the micro- and nanoscopic arrangement of fibrillar type I collagen along Hydra’s body axis using high-resolution microscopy and X-ray scattering. Elasticity mapping of the ECM ex vivo revealed distinctive elasticity patterns along the body axis. A proteomic analysis of the ECM showed that these elasticity patterns correlate with a gradient-like distribution of metalloproteases along the body axis. Activation of the Wnt/β-catenin pathway in wild-type and transgenic animals alters these patterns toward low ECM elasticity patterns. This suggests a mechanism whereby high protease activity under control of Wnt/β-catenin signaling causes remodeling and softening of the ECM. This Wnt-dependent spatiotemporal coordination of biochemical and biomechanical cues in ECM formation was likely a central evolutionary innovation for animal tissue morphogenesis.
... Importantly, ECM damage doesn't seem to be an issue with the "immortal" Hydra vulgaris 4 . H. vulgaris has a body column with cells that continuously divide -driving cells out towards its extremities. ...
Aging kills 100,000 people a day - more than any other cause of death combined. The exact causes of aging have been much discussed, but the most pressing issue with regard to aging appears to me to be lipofuscin accumulation. That is, the accumulation of indigestible cellular garbage that needs to be removed from our cells, then the body. In this piece, I will explain why I think “getting rid of the garbage” should be at least one of our main goals with regard to longevity research for now.
... Importantly, ECM damage doesn't seem to be an issue with the "immortal" Hydra vulgaris 4 . H. vulgaris has a body column with cells that continuously divide -driving cells out towards its extremities. ...
Aging kills 100,000 people a day - more than any other cause of death combined. The exact causes of aging have been much discussed, but the most pressing issue with regard to aging appears to me to be lipofuscin accumulation. That is, the accumulation of indigestible cellular garbage that needs to be removed from our cells, then the body. In this piece, I will explain why I think “getting rid of the garbage” should be at least one of our main goals with regard to longevity research for now.
... Thus, the fibronectin antibody seems to have detected the average movement of multiple ECMs; it would be interesting to also examine the movement of basement membrane-specific markers such as type IV collagen and laminin. Antibody-based live imaging was also used to examine many other ECM movements: the classical report of the basement membrane movement during avian gastrulation (section 2.1) [54] was recently supported by a new study [62]; hydra mesogloea was found to be moving in the body of this simple animal [63]. Details of these work will be discussed later (section 2.6). ...
... However, in the head, while mesogloea was immobile, epithelial cells left the stationary matrix and moved into tentacles. In the newly forming bud, while epithelial cells moved into the bud from the mother body, only a small amount of the mother hydra's mesogloea moved into the growing daughter [63]. ...
... If the ECM is not moving, the cells are moving towards a higher concentration of the fixed signalling factor. However, if the ECM is moving with the cells as in the cases with the avian epiblast basement membrane or hydra mesogloea (section 2.6) [62,63], during the migration each moving cell is exposed to a constant level of the signalling molecule. More investigations are needed to understand how moving ECMs in vivo signal to the cells in/on them [62]. ...
Extracellular matrices (ECMs) are essential for the architecture and function of animal tissues. ECMs have been thought to be highly stable structures; however, too much stability of ECMs would hamper tissue remodelling required for organ development and maintenance. Regarding this conundrum, this article reviews multiple lines of evidence that ECMs are in fact rapidly moving and replacing components in diverse organisms including hydra, worms, flies, and vertebrates. Also discussed are how cells behave on/in such dynamic ECMs, how ECM dynamics contributes to embryogenesis and adult tissue homoeostasis, and what molecular mechanisms exist behind the dynamics. In addition, it is highlighted how cutting-edge technologies such as genome engineering, live imaging, and mathematical modelling have contributed to reveal the previously invisible dynamics of ECMs. The idea that ECMs are unchanging is to be changed, and ECM dynamics is emerging as a hitherto unrecognized critical factor for tissue development and maintenance.
... The diversity of available construct designs ensures a broad application range of the transgenic hydra technology and allows constitutive gene gain-and loss-of-function analyses, as well as conditional gene manipulation, dissection of cis-regulatory sequences, differential labeling and in vivo visualization of the entire repertoire of cell types in a polyp. In addition, the visualization of hydra development and regeneration has advanced in recent years, with the addition of fluorescent reporters and sophisticated live-imaging approaches (Aufschnaiter et al. 2011;Carter et al. 2016;Szymanski and Yuste 2019;Giez et al. 2021). Finally, a new generation of sequencing technologies has uncovered that hydra is colonized with microbes. ...
Lynn Margulis has made it clear that in nature partnerships are the predominant form of life; that life processes can only be understood in terms of the interactions of such partnerships; and that their inherent complexity can only be understood by taking a holistic approach. Here I attempt to relate Lynn Margulis´ observations on the freshwater polyp hydra to the perceptions and problems of today’s Hydra research. To accomplish this, I will synthesize our current understanding of how symbionts influence the phenotype and fitness of hydra. Based on this new findings, a fundamental paradigm shift and a new era is emerging in the way that we consider organisms such as hydra as multi-organismic metaorganisms, just as Lynn Margulis may have thought about it.
... 1994), cell differentiation (Yan et al. 2000a,b), and regeneration (Deutzmann et al. 2000). In vivo labeling experiments revealed that the mesoglea gets shifted toward the extremities concomitantly with epithelial cells, except in the apical part where the mesoglea remains static (Aufschnaiter et al. 2011). The mesoglea is involved in morphogenetic processes leading to head formation as pharmacological agents or blocking antibodies to ECM components inhibit regeneration (Sarras 2012;Bergheim and Özbek 2019). ...
Here we discuss the developmental and homeostatic conditions necessary for Hydra regeneration. Hydra is characterized by populations of adult stem cells paused in the G2 phase of the cell cycle, ready to respond to injury signals. The body column can be compared to a blastema-like structure, populated with multifunctional epithelial stem cells that show low sensitivity to proapoptotic signals, and high inducibility of autophagy that promotes resistance to stress and starvation. Intact Hydra polyps also exhibit a dynamic patterning along the oral-aboral axis under the control of homeostatic organizers whose activity results from regulatory loops between activators and inhibitors. As in bilaterians, injury triggers the immediate production of reactive oxygen species (ROS) signals that promote wound healing and contribute to the reactivation of developmental programs via cell death and the de novo formation of new organizing centers from somatic tissues. In aging Hydra, regeneration is rapidly lost as homeostatic conditions are no longer pro-regenerative.
... In bilaterians and cnidarians, epithelial morphogenesis has been shown to rely strongly on interactions between receptors on the epithelial sheet and components of the extracellular matrix (ECM), including the basement membrane when it is present (Aufschnaiter et al., 2011;Dzamba and DeSimone, 2018;Fidler et al., 2017;Sekiguchi and Yamada, 2018). A few genes encoding important extracellular matrix proteins or their cellular receptors predate the emergence of Metazoa; indeed, genes encoding integrins and integrin adhesion machinery are present in unicellular relatives of metazoans (see section 2.2) (Abedin and King, 2010;Babonis and Martindale, 2017;. ...
The evolution of animal diversity is strongly affected by the origin of novel cell and tissue types and their interactions with each other. Understanding the evolution of cell types will shed light on the evolution of novel structures, and in turn highlight how animals diversified. Several cell types may also have been lost as animals simplified – for example did sponges have nerves and lose them? This book reveals the interplay between gains and losses and provides readers with a better grasp of the evolutionary history of cell types. In addition, the book illustrates how new cell types allow a better understanding permitting the discrimination between convergence and homology.
... Inhibition of lysyl oxidase prevents the components of the extracellular matrix from polymerizing. This has been shown before to be effective in inhibition of the Hydra extracellular matrix (Aufschnaiter et al., 2011). A concentration of 100 μmol l −1 has been shown to be effective in other strains of Hydra. ...
... All the cells in a polyp are known to be pushed towards the termini of the body and sloughed off. The extracellular matrix associated with these cells is also reported to move along with these cells and is degraded at the tentacle tip or the basal disk (Aufschnaiter et al., 2011). Strangely, the aforesaid behavior changes at the shoulder region with a reduction in the cell-extracellular matrix velocities. ...
... Collagen, as shown here, plays an important role in tissue stiffness, possibly both through cell-extracellular matrix interactions and varying extracellular matrix composition (Shostak et al., 1965;Aufschnaiter et al., 2011;Zhang et al., 2007;Shimizu et al., 2008;Sarras, 2012). The collagen fiber structure in the extracellular matrix can be dynamically regulated depending on the strain experienced locally . ...
The bell-shaped members of Cnidaria typically move around by swimming, whereas the Hydra polyp can perform locomotion on solid substrates in aquatic environment. To address the biomechanics of locomotion on rigid substrates, we studied the 'somersaulting' locomotion in Hydra. We applied atomic force microscopy to measure the local mechanical properties of Hydra's body column and identified the existence of differential Young's modulus between the shoulder region versus rest of the body column at 3:1 ratio. We show that somersault primarily depends on differential tissue stiffness of the body column and is explained by computational models that accurately recapitulate the mechanics involved in this process. We demonstrate that perturbation of the observed stiffness variation in the body column by modulating the extracellular matrix (ECM) polymerization impairs the ‘somersault' movement. These results provide mechanistic basis for the evolutionary significance of differential extracellular matrix properties and tissue stiffness.
