Periodic Reporting for period 4 - Ca2Coral (Elucidating the molecular and biophysical mechanism of coral calcification in view of the future acidified ocean)
Berichtszeitraum: 2022-07-01 bis 2023-12-31
Although various aspects of biomineralisation in corals have been studied for decades, the basic mechanism of precipitation of the aragonite skeleton remains enigmatic. In this project we proposed to test the core hypothesis that, unless wounded or otherwise having skeletal material exposed directly to seawater, stony zooxanthellate corals will continue to calcify at pH values projected for the CO2 emissions scenarios for 2100.
Specifically, the objectives of Ca2Coral are to:
1) Use functional genomics to identify the key genes and proteins involved both in the organic matrix and skeleton formation in the adult holobiont and during its larval development.
2) Use a genetics approach to elucidate the roles of specific proteins in the biomineralisation process.
3) Use ultra-high resolution imaging and spectroscopic analysis at different pH levels to elucidate the biomineralisation pathways and mineral precursor in corals in the adult holobiont and during its larval development.
Specifically, the objectives of Ca2Coral are to:
1) Use functional genomics to identify the key genes and proteins involved both in the organic matrix and skeleton formation in the adult holobiont and during its larval development.
2) Use a genetics approach to elucidate the roles of specific proteins in the biomineralisation process.
3) Use ultra-high resolution imaging and spectroscopic analysis at different pH levels to elucidate the biomineralisation pathways and mineral precursor in corals in the adult holobiont and during its larval development.
Objective 1: Identify Key Genes and Proteins in Coral Skeleton Formation
Protein Analysis: We developed the best method to extract and study proteins from coral skeletons, and we identified key proteins involved in building coral skeletons. Our findings suggest that these proteins are transported to the skeleton through vesicles within the coral cells. Based on our findings, we proposed a three-stage model of coral skeleton formation (Fig. 1)
Evolutionary Study: We examined the evolution of these key proteins across different coral species, helping us understand how these proteins and processes have developed over time.
Gene Analysis: We created a detailed list of genes involved in coral skeleton formation. This included generating a coral cell atlas, which maps gene activity in different cell types and life stages, aiding researchers worldwide (Fig. 4).
Objective 2: Understand the Role of Specific Proteins in Skeleton Formation
We tried using a genetic approach to study the role of specific proteins in coral skeleton formation but faced challenges. However, using lab experiments, we confirmed that certain coral proteins help form the crystalline structure of the skeleton.
Objective 3: Discover How Corals Form Their Skeletons
Mineral Formation: We discovered that corals initially form their skeletons from a less stable form of calcium carbonate, which then matures into the harder structure seen in coral skeletons. This process involves several steps and different types of minerals and proteins (Fig. 1).
Impact of Ocean Acidification: We studied how lower pH levels in seawater affect young corals and their algae partners. While acidified water negatively impacted coral larvae survival, it boosted algae growth. This research highlights the need to understand how ocean acidification affects coral development and survival.
Ion Transport: Using advanced imaging and genetic tools, we found that ions from seawater are transported to the skeleton-building site via vesicles within coral cells (Fig. 1).
Precursor for Skeleton Formation: We identified proteins and particles involved in the early stages of skeleton formation. These components help in the initial formation of the skeleton and its growth.
3D Skeleton Study: We developed an AI tool to study the 3D structure of coral skeletons, which helps us understand how different growth zones develop and how ocean acidification affects them (Fig. 2).
Overall, our research has provided significant insights into how corals build their skeletons and how they might be affected by changing ocean conditions, paving the way for further studies and conservation efforts.
Protein Analysis: We developed the best method to extract and study proteins from coral skeletons, and we identified key proteins involved in building coral skeletons. Our findings suggest that these proteins are transported to the skeleton through vesicles within the coral cells. Based on our findings, we proposed a three-stage model of coral skeleton formation (Fig. 1)
Evolutionary Study: We examined the evolution of these key proteins across different coral species, helping us understand how these proteins and processes have developed over time.
Gene Analysis: We created a detailed list of genes involved in coral skeleton formation. This included generating a coral cell atlas, which maps gene activity in different cell types and life stages, aiding researchers worldwide (Fig. 4).
Objective 2: Understand the Role of Specific Proteins in Skeleton Formation
We tried using a genetic approach to study the role of specific proteins in coral skeleton formation but faced challenges. However, using lab experiments, we confirmed that certain coral proteins help form the crystalline structure of the skeleton.
Objective 3: Discover How Corals Form Their Skeletons
Mineral Formation: We discovered that corals initially form their skeletons from a less stable form of calcium carbonate, which then matures into the harder structure seen in coral skeletons. This process involves several steps and different types of minerals and proteins (Fig. 1).
Impact of Ocean Acidification: We studied how lower pH levels in seawater affect young corals and their algae partners. While acidified water negatively impacted coral larvae survival, it boosted algae growth. This research highlights the need to understand how ocean acidification affects coral development and survival.
Ion Transport: Using advanced imaging and genetic tools, we found that ions from seawater are transported to the skeleton-building site via vesicles within coral cells (Fig. 1).
Precursor for Skeleton Formation: We identified proteins and particles involved in the early stages of skeleton formation. These components help in the initial formation of the skeleton and its growth.
3D Skeleton Study: We developed an AI tool to study the 3D structure of coral skeletons, which helps us understand how different growth zones develop and how ocean acidification affects them (Fig. 2).
Overall, our research has provided significant insights into how corals build their skeletons and how they might be affected by changing ocean conditions, paving the way for further studies and conservation efforts.
Through our research, we have resolved a century-long debate on the coral formation mechanism. We discovered that the coral mineral precursor is amorphous calcium carbonate, which is formed in intracellular compartments. This finding indicates that coral skeleton formation is less influenced by ocean acidification due to the growth of the skeleton by attachment of ions from solution or amorphous particles from intracellular vesicles. This mechanism spatially separates the amorphous particles and the coral skeleton's growing surface from seawater, making coral growth and reef formation less susceptible to ocean acidification.
Additionally, although the initial aim was not to develop a coral cell atlas, our pursuit of understanding cellular control over mineral formation led to its creation. This atlas has become a significant tool for targeted research and a valuable resource for the global coral research community.
Achievements:
Identification of Core Biomineralization Toolkit Proteins: We successfully identified and characterized the fundamental proteins constituting the biomineralization toolkit. This achievement has garnered substantial citations and widespread usage.
Resolution of Coral Formation Mechanism: We addressed and resolved a 100-year-long debate by finding that the coral mineral precursor is amorphous calcium carbonate formed in intracellular compartments, thus distancing it from bulk solution and equilibrium thermodynamics.
Discovery of Coral Skeleton Formation Resilience: We demonstrated that coral skeleton formation shows resilience against ocean acidification due to the counterbalance between mineral and organic processes and the attachment of ions or amorphous particles from intracellular vesicles.
Creation of the Coral Cell Atlas: We pioneered the creation of the inaugural stony coral cell atlas, complemented by an interactive database designed to facilitate community access and utilization. Although it was not initially planned but emerged as a crucial tool for understanding cellular control over mineral formation, facilitating targeted research (Fig. 4).
Publication of Groundbreaking Insights: We summarized our groundbreaking insights into coral biomineralization through two invited review papers, providing a comprehensive overview of our findings.
Global Impact on Coral Research: The coral cell atlas and our findings have evolved into globally valuable tools, significantly contributing to the broader coral research community's efforts in understanding and preserving coral reefs.
Additionally, although the initial aim was not to develop a coral cell atlas, our pursuit of understanding cellular control over mineral formation led to its creation. This atlas has become a significant tool for targeted research and a valuable resource for the global coral research community.
Achievements:
Identification of Core Biomineralization Toolkit Proteins: We successfully identified and characterized the fundamental proteins constituting the biomineralization toolkit. This achievement has garnered substantial citations and widespread usage.
Resolution of Coral Formation Mechanism: We addressed and resolved a 100-year-long debate by finding that the coral mineral precursor is amorphous calcium carbonate formed in intracellular compartments, thus distancing it from bulk solution and equilibrium thermodynamics.
Discovery of Coral Skeleton Formation Resilience: We demonstrated that coral skeleton formation shows resilience against ocean acidification due to the counterbalance between mineral and organic processes and the attachment of ions or amorphous particles from intracellular vesicles.
Creation of the Coral Cell Atlas: We pioneered the creation of the inaugural stony coral cell atlas, complemented by an interactive database designed to facilitate community access and utilization. Although it was not initially planned but emerged as a crucial tool for understanding cellular control over mineral formation, facilitating targeted research (Fig. 4).
Publication of Groundbreaking Insights: We summarized our groundbreaking insights into coral biomineralization through two invited review papers, providing a comprehensive overview of our findings.
Global Impact on Coral Research: The coral cell atlas and our findings have evolved into globally valuable tools, significantly contributing to the broader coral research community's efforts in understanding and preserving coral reefs.