In spite of more than one century and half of studies, mechanisms of coral biomineralization, leading to coral growth and reef formation, still remain poorly known, although major global threats to coral reefs, such as ocean acidification, primarily affect this process. Coral skeletons are used as environmental archives but the vital processes that govern incorporation of trace elements and stable isotope are still unknown. Our knowledge on coral physiology is restricted to the organismal level due to the lack of appropriate cell model, however the advent of new approaches, such as coral genomic, is changing drastically our knowledge on these animals even if only a few data are available concerning the field of biomineralization. This chapter reviews our present knowledge and discusses the different theories on coral calcification, from the molecular to the reef level. Conclusion is presented in a list of key issues to be resolved in order to understand the intimate mechanisms of calcification of corals, essential to determine the origin of the sensitivity of corals to ocean acidification, to improve paleoceanographic reconstructions or coral reef management, or “just” to understand how genes of a soft organism control the formation of an extracellular 3D-skeleton.

Coral Calcification, Cells to Reefs

Biomineralized structures and tissues are composites, containing a biologically produced organic matrix and nano- or microscale amorphous or crystalline minerals. Two main examples of organic matrices – the amino-polysaccharide chitin and the asymmetric protein collagen – are presented and discussed as the basic structural modules and organo-templates for calcium and silica biomineralization in nature. Both serve as templates, providing preferential sites for nucleation and controlling the location and orientation of mineral phases. Here, for the first time, chitin and collagen are analysed from evolutionary, structural, and functional points of view with respect to their templating properties in calcification and silicification phenomena, using both in vivo and in vitro data. It is proposed that these biopolymers be characterized as fundamental templates in biomineralization, inasmuch as they are very ancient from an evolutionary point of view, common to many species and biological systems with a global ...

Chitin and collagen as universal and alternative templates in biomineralization

In the course of evolution nature developed materials based on organic–inorganic nanocomposites with complex, hierarchical organization from A u ngstroms to millimeters tailored via molecular self-assembly. [1–3] Such materials possess outstanding stiffness, toughness, and strength related to their low density, while the mechanical characteristics of their underlying constituents are rather modest. [2,4] This remarkable performance is a consequence of their hierarchical structure, the specific design at each level of organization, and the inherent strong heterogeneity [4] resulting in the accommodation of macroscopic loadings bydifferentdeformationmechanisms at differentlength scales. Therefore, to understand the macroscopic mechanical properties of the tissue, one should take into account its structure–property relations at all length scales down to the molecular level. To date, this key challenge has been only partly addressed due to severe obstacles in obtaining mechanical and structural data at the nanometer scale. The mechanical properties of important proteins and biominerals as well as some details about their exact structure are still unknown. A powerful tool to overcome these difficulties and to better understand the structure–property relationships in biomaterials is multiscale modeling encompassing all length scales. [3,5] Some progress in the development of multiscale structure–property relationships for mineralized tissues has been achieved by combined modeling and experimental approaches applied to bone, [4] nacre, [6] and fish skin armor. [7] However, these approaches do not explicitly integrate a molecular-level description and use continuum mechanics at the meso- and macroscale (e.g., finite element analysis) coupled with experimental data obtained, for example, by nanoindentation. A

Revealing the design principles of high-performance biological composites using ab initio and multiscale simulations: the example of lobster cuticle.

This article reviews the morphogenesis, morphology, histology, ultrastructure, and structural-functional relationships of the hepatopancreas, the main metabolic organ of the Decapoda. The hepatopancreas develops in early larval stages from a pair of lateral lobes of the midgut anlage. In adults, it consists of hundreds of blindly ending tubules that are enveloped by a muscle net consisting of longitudinal and circular fibers. Stem cells at the distal ends of the tubules give rise to three ultrastructurally different epithelial cell types, the R-, F-, and B-cells. Histochemistry, immunohistochemistry, in situ hybridization, and monitoring of ultrastructural changes under different experimental conditions allowed the attribution of functions to these cell types. R-cells serve for the absorption and metabolization of nutrients, storage of energy reserves and minerals, synthesis of lipoproteins for export to other organs, detoxification of heavy metals, and excretion of uric acid. F-cells synthesize digestive enzymes and blood proteins involved in oxygen transport and immune defense. They also detoxify some heavy metals and probably organic xenobiotics. B-cells are assumed to produce and recycle fat emulsifiers. The hepatopancreas tubules lack nerves. The presence of scattered M-cells with putative endocrine function in the epithelium suggests that the hepatopancreas is mainly hormonally controlled. M-cells probably represent a self-perpetuating cell lineage independent from E-cells. The interstitium between the tubules contains connective tissue, arterioles, hemolymph with circulating hemocytes, and fixed phagocytes that eliminate pathogens. The hepatopancreas is histologically and ultrastructurally uniform throughout the Decapoda, despite their broad variety in body size, morphology, life style, and ecology. However, in a few cavernicolous and deep-sea shrimps parts of the hepatopancreas are transformed into large oil storing and bioluminescent compartments. Within the malacostracan crustaceans, the hepatopancreas of the Decapoda is most similar to the digestive gland of the Euphausiacea, supporting close taxonomic relationship of these two taxa.

Functional cytology of the hepatopancreas of decapod crustaceans.

Collagen mineralization is a biological process in many skeletal elements in the animal kingdom. Examples of these collagen-based skeletons are the siliceous spicules of glass sponges or the intrafibrillar hydroxyapatite platelets in vertebrates. The mineralization of collagen in vitro has gained interest for two reasons: understanding the processes behind bone formation and the synthesis of scaffolds for tissue engineering. In this paper, the efforts toward collagen mineralization in vitro are reviewed. First, general introduction toward collagen type I, the main component of the extracellular matrix in animals, is provided, followed by a brief overview of collagenous skeletons. Then, the in vitro mineralization of collagen is critically reviewed. Due to their biological abundance, hydroxyapatite and silica are the focus of this review. To a much lesser extent, also some efforts with other minerals are outlined. Combining all minerals and the suggested mechanisms for each mineral, a general mechanism for the intrafibrillar mineralization of collagen is proposed. This review concludes with an outlook for further improvement of collagen-based tissue engineering scaffolds.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.202004418

In Vitro Mineralization of Collagen.

Mobilization of calcium during the molt cycle from the cuticle to transient calcium deposits is widely spread in crustaceans. The dynamics of calcium transport to transient calcium deposits called gastroliths and to the cu- ticle over the course of the molt cycle were studied in the crayfish Cherax quadricarinatus. In this species, calcium was deposited in the gastroliths during premolt and trans- ported back to the cuticle during postmolt, shown by digital X-ray radiograph analysis. The predominant mineral in the crayfish is amorphous calcium carbonate embedded in an organic matrix composed mainly of chitin. Scanning elec- tron micrographs of the cuticle during premolt showed that the endocuticle and parts of the exocuticle were the source of most of the labile calcium, while the epicuticle did not undergo degradation and remained mineralized throughout the molt cycle. The gastroliths are made of concentric layers of amorphous calcium carbonate intercalated between chiti- nous lamella. Measurements of pH and calcium levels dur- ing gastrolith deposition showed that calcium concentra- tions in the gastroliths, stomach, and muscle were about the same (10 to 11 mmol l 1 ). On the other hand, pH varied greatly, from 8.7 0.15 in the gastrolith cavity through 7.6 0.2 in muscle to 6.9 0.5 in the stomach.

Reciprocal changes in calcification of the gastrolith and cuticle during the molt cycle of the red claw crayfish Cherax quadricarinatus.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Mor Grinstein

Author Tools

Chat about Author

Papers

Reciprocal changes in calcification of the gastrolith and cuticle during the molt cycle of the red claw crayfish Cherax quadricarinatus.