Toward a chronology of Haliotis fulgens, with a review of abalone shell microstructure

1995 ◽  
Vol 46 (3) ◽  
pp. 607 ◽  
Author(s):  
SA Shepherd ◽  
M Avalos-Borja ◽  
MO Quintanilla
Keyword(s):  
Organic Matrix ◽  
Spawning Season ◽  
First Year ◽  
Shell Microstructure ◽  
Sea Temperature ◽  
Abalone Shell

The microstructure of the shell of the abalone Haliotis fulgens consists of alternate layers of aragonite and prismatic calcium with darker organic matrix (conchiolin) that are visible as rings when the shell is ground down at the spire. This abalone deposits about four prismatic layers in the first year and three layers each year thereafter at the site studied. Prismatic layers are laid down in about April, August and November, corresponding with sea temperature minima and maxima and with the spawning season. After about 3 years of age, prismatic layers at the spire of the shell begin to be lost through erosion of the outer layers of the shell. The first prismatic layers deposited are 5-10 �m across, and later layers successively increase in thickness to a maximum of about 80 �m. This property is used to estimate the rate of erosion of layers, which is about one per annum. When the rate of deposition and the rate of erosion are known for a locality, an estimate of the true age can be made. The findings are considered in relation to the microstructure of the abalone shell.

Genetic Coding in Biomineralization of Microlaminate Composites

1992 ◽  
Vol 292 ◽  
Author(s):  
Daniel E. Morse ◽  
Marios A. Cariolou ◽  
Galen D. Stucky ◽  
Charlotite M. Zaremba ◽  
Paul K. Hansma
Keyword(s):  
Organic Matrix ◽  
Nucleation And Growth ◽  
Direct Crystallization ◽  
Basic Principles ◽  
Shell Matrix ◽  
Additional Protein ◽  
Flexible Deformation ◽  
Abalone Shell ◽  
Crystalline Domains ◽  
Present Understanding

AbstractBiomineralization is precisely controlled by complex templating relationships ultimately encoded in the genes. In the formation of the molluscan shell, polyanionic pleated sheet proteins serve as templates for the nucleation and epitaxial growth of calcium carbonate crystalline domains to yield microlaminate composites of exceptional strength and crystal ordering. The strength and fracture-resistance of these composites far exceed those of the minerals themselves, as a result of both the capacity for flexible deformation of the organic matrix layers and the retardation of crack propagation at each mineral-organic interface. The basic principles controlling low temperature biosynthesis of these materials thus are of both fundamental and applied importance. The abalone shell consists of microlaminates with a remarkable regularity of lamina thickness (ca. 0.5 micron), the formation of which defies present understanding. We have found that shells of abalone larvae formed prior to metamorphosis contain only aragonite, whereas the adult shell made after metamorphosis contains both aragonite and calcite. This transition is accompanied by a switch in genetic expression of the template proteins, suggesting that the premetamorphic protein may serve as a template for aragonite nucleation and growth, while template proteins synthesized after metamorphosis may direct crystallization of calcite. These analyses are based on improvements we recently reported for the detection and purification of proteins from the demineralized shell matrix. Genetic cloning experiments now in progress are aimed at discovering additional protein sequences responsible for the programmed control of crystal phase termination, since it is the termination and reinitiation of mineralization that is responsible for the regularity of highly ordered microlaminates produced in nature.

Paleoenvironmental reconstruction in La Paz Bay, Gulf of California: Evidence from δ18O in Chione californiensis

The Holocene ◽  
2021 ◽  
pp. 095968362110665
Author(s):  
Fernando Arenas ◽  
Harumi Fujita ◽  
Alberto Sánchez
Keyword(s):  
Gulf Of California ◽  
First Year ◽  
Paleoenvironmental Reconstruction ◽  
La Paz ◽  
Sea Temperature ◽  
The Past ◽  
Stable Oxygen ◽  
First Year Of Life ◽  
Summer Growth ◽  
Bivalve Shells

Oceanic characteristics of the Holocene are used to understand climatic patterns and phenomena that affect marine and human communities. Likewise, past marine conditions can be reconstructed from surface sea temperature (SST), using stable oxygen isotopes in bivalve shells. The objective of this study was to calculate Holocene summer SSTs for La Paz Bay, by analyzing δ18O of 14C dated bivalve shells ( Chione californiensis) from a Holocene camp site located in Cañada de La Enfermería, Baja California Sur, México. Aragonite was extracted from the shells’ umbo, representing the summer growth season during the first year of life. δ18O value of C. californiensis is −1.9 ± 0.1‰ at present, and varied between −1.3‰ and −2.6‰ during the last 9 ky. In 9469 BP, 8396 BP, and 7708 BP, δ18O values were similar to those of the present. In 7857 BP, 7805 BP, and 7804 BP, δ18O was 18O depleted (0.6–0.9‰), indicating warmer summer SSTs versus the present. In 7070 BP, 6945 BP, and 2087 BP, δ18O was enriched in 18O (0.3–0.4‰), suggesting colder SSTs versus the present. This study coincides with other paleotemperature studies for the region and allows us to address the effect of changing SST on this marine resource, its use by human communities of the past, and its effects on human presence in the area with respect to climate variability.

Structure Characteristics of the Hemifusus tuba Conch Shell

2011 ◽  
Vol 675-677 ◽  
pp. 365-368
Author(s):  
Yan Liang ◽  
Jie Zhao ◽  
Cheng Wei Wu ◽  
Chen Xiao Mu
Keyword(s):  
Organic Molecules ◽  
Lamellar Microstructure ◽  
Organic Matrix ◽  
The Body ◽  
Functional Adaptation ◽  
Shell Microstructure ◽  
Body Shell ◽  
Sea Area ◽  
Conch Shell ◽  
Mollusk Shell

The mollusk shell mobilizes calcium from environment for skeletal mineralization. This occurs through synthesizing solids in solution in the presence of organic molecules of specific interior regions of the conch shell. The ultrastructure of the Hemifusus tuba conch shell living in the Huang/Bo sea area is investigated in the paper. It is shown that the composition and microstructure of the mollusk shell vary in different positions. The prodissoconch shell consists only of aragonite with the crossed-lamellar microstructure. While the spiral shell and the body shell of the Hemifusus tuba conch shell are composed of one calcite layer and several aragonite layers. The calcite layer consists of cylindrical grains, but the aragonite layers are crossed-lamellar ultrastructure. The margin of shell aperture is only composed of calcite with cylindrical grains. This natural optimization of the shell microstructure is intimately due to the growth of the organic matrix. The process of growth allows a constant renewal of the material, thus enabling the functional adaptation of the shells.

Exceptional preservation of organic matrix and shell microstructure in a Late Cretaceous Pinna fossil revealed by photoemission electron spectromicroscopy

Geology ◽  
2018 ◽  
Vol 46 (8) ◽  
pp. 711-714 ◽  
Author(s):  
Corinne E. Myers ◽  
Kristin D. Bergmann ◽  
Chang-Yu Sun ◽  
Nicholas Boekelheide ◽  
Andrew H. Knoll ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Organic Matrix ◽  
Shell Microstructure ◽  
Exceptional Preservation ◽  
Photoemission Electron

In situ transmission electron microscopy observation of reversible deformation in nacre organic matrix

2008 ◽  
Vol 23 (5) ◽  
pp. 1466-1471 ◽  
Author(s):  
Taro Sumitomo ◽  
Hideki Kakisawa ◽  
Yusuke Owaki ◽  
Yutaka Kagawa
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mechanical Performance ◽  
Protein Structures ◽  
Organic Matrix ◽  
Organic Polymer ◽  
Transmission Electron ◽  
Strong Adhesion ◽  
Abalone Shell

The deformation behavior of the organic polymer matrix of the biocomposite nacre structure in abalone shell was investigated by in situ straining during transmission electron microscopy (TEM). We observed strong adhesion to mineral plates and high ductility of the organic matrix, confirming a crack-bridging toughening mechanism. In addition, direct observation of reversible mechanical behavior was made in the viscoelastic reformation of matrix ligaments after failure. Crystalline β-sheet structures identified through electron diffraction suggested the presence of protein structures similar to spider or cocoon silk, and the reversible mechanism was attributed to hydration-induced unfolding and refolding of domains in these silklike proteins. This work provides further insight into the molecular and nanoscale behavior of nacre organic matrix and its contribution to bulk mechanical performance.

Toughening mechanisms in abalone shell

1990 ◽  
Vol 48 (4) ◽  
pp. 196-197
Author(s):  
Katie E. Gunnison ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Mechanical Properties ◽  
Matrix Material ◽  
Organic Matrix ◽  
Fold Increase ◽  
Mechanical Tests ◽  
Polymer Composite Material ◽  
Biological Macromolecules ◽  
Toughening Mechanisms ◽  
Haliotis Rufescens ◽  
Abalone Shell

Abalone shell (Haliotis Rufescens) is a naturally ocurring ceramic/polymer composite material. The system displays a unique laminated structure of calcium carbonate (aragonite) crystals in a matrix of biological macromolecules. The CaCO3 crystals and the organic matrix are arranged in a miniature “brick and mortar” structure referred to as nacre. Figure 1 is a TEM bright field micrograph illustrating the high degree of order observed in this microstructure.Although the nacre region of the shell is more than 95% CaCO3 by volume, the natural matrix material and the arrangement of the microstructure lead to a substantial increase in the observed mechanical properties. Mechanical tests performed on the nacre region show a fifty-fold increase over that of pure bulk CaCO3 (Fig. 2), which also compares with other ceramic and cermet systems.Vickers microhardness testing was performed on samples polished for optical microscopy. Crack propagation features were observed by standard SEM techniques and analyzed in an attempt to identify the possible toughening mechanisms that are operating in the nacre structure. The cracks generally travel by a tortuous path, often displaying microcracks and crack branching. However, these mechanisms alone are not sufficient to account for the observed mechanical properties.

Arctic coccolithophorids: two species of Turrisphaera gen. nov. from West Greenland, Alaska, and the Northwest Passage

1976 ◽  
Vol 194 (1115) ◽  
pp. 179-194 ◽  
Keyword(s):  
Type Species ◽  
Cold Water ◽  
Organic Matrix ◽  
Migration Route ◽  
Sea Temperature ◽  
Perforated Plates ◽  
Northwest Passage ◽  
The Pacific ◽  
Resolute Bay ◽  
Unusual Type

Turrisphaera gen. nov. is characterized by an unusual type of calcification in which small hexagonal crystallites, shaped like perforated plates or rings, are reticulately arranged within an organic matrix responsible for the tubular or tower-like coccolith morphology. T. borealis sp. nov., the type species which is described, has been found living in very cold water ( – 1 °C) in the middle of the Northwest Passage as well as near the adjacent oceans at each end where the sea temperature is higher. In the coldest locality (Resolute Bay), typical T. borealis, though present, was outnumbered by deviants described here as a second species, T. arctica sp. nov., perhaps alternatively interpretable as locally induced growth-forms. Comparisons with other living and fossil taxa indicate fewer points of resemblance between Turrisphaera and other known coccolithophorids than between it and several species of the wholly unmineralized genus Chrysochromulina . Finally the geographical distribution suggests that in this particular case the Northwest Passage could be a significant migration route from the Pacific to the Atlantic Ocean.

A Protozoan Model for Golgi-Associated Calcification

1971 ◽  
Vol 29 ◽  
pp. 332-333
Author(s):  
D. C. Williams ◽  
D. E. Outka
Keyword(s):  
Golgi Apparatus ◽  
Organic Matrix ◽  
Model System ◽  
Sequential Formation

Many studies have shown that the Golgi apparatus is involved in a variety of synthetic activities, and probably no Golgi product is more elaborate than the scales produced by various kinds of phytoflagellates. The formation of calcified scales (coccoliths, Fig. 1,2) of the coccolithophorid phytoflagellates provides a particularly interesting model system for the study of biological mineralization, and the sequential formation of Golgi products.The coccoliths of Hymenomonas carterae consist of a scale-like base (Fig. 2 and 4, b) with a highly structured calcified (CaCO3) rim composed of two distinct elements which alternate about the base periphery (Fig. 1 and 3, A, B). Each element is enveloped by a sheath-like organic matrix (Fig. 3; Fig. 4, m).

Human Enamel Replication

1976 ◽  
Vol 34 ◽  
pp. 180-181
Author(s):  
Norman L. Dockum ◽  
John G. Dockum
Keyword(s):  
Organic Matrix ◽  
Human Teeth ◽  
Human Enamel ◽  
Straight Line ◽  
Ultrastructural Characteristics

Ultrastructural characteristics of fractured human enamel and acid-etched enamel were compared using acetate replicas shadowed with platinum and palladium. Shadowed replications of acid-etched surfaces were also obtained by the same method.Enamel from human teeth has a rod structure within which there are crystals of hydroxyapatite contained within a structureless organic matrix composed of keratin. The rods which run at right angles from the dentino-enamel junction are considered to run in a straight line perpendicular to the perimeter of the enamel, however, in many areas these enamel rods overlap, interlacing and intertwining with one another.

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