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  • 1
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    Sea shell diversity and rapidly evolving secretomes: insights into the evolution of biomineralization. (2018)
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    Publication Date: 2021-04-25
    Description: An external skeleton is an essential part of the body plan of many animals and is thought to be one of the key factors that enabled the great expansion in animal diversity and disparity during the Cambrian explosion. Molluscs are considered ideal to study the evolution of biomineralization because of their diversity of highly complex, robust and patterned shells. The molluscan shell forms externally at the interface of animal and environment, and involves controlled deposition of calcium carbonate within a framework of macromolecules that are secreted from the dorsal mantle epithelium. Despite its deep conservation within Mollusca, the mantle is capable of producing an incredible diversity of shell patterns, and macro- and micro-architectures. Here we review recent developments within the field of molluscan biomineralization, focusing on the genes expressed in the mantle that encode secreted proteins. The so-called mantle secretome appears to regulate shell deposition and patterning and in some cases becomes part of the shell matrix. Recent transcriptomic and proteomic studies have revealed marked differences in the mantle secretomes of even closely-related molluscs; these typically exceed expected differences based on characteristics of the external shell. All mantle secretomes surveyed to date include novel genes encoding lineage-restricted proteins and unique combinations of co-opted ancient genes. A surprisingly large proportion of both ancient and novel secreted proteins containing simple repetitive motifs or domains that are often modular in construction. These repetitive low complexity domains (RLCDs) appear to further promote the evolvability of the mantle secretome, resulting in domain shuffling, expansion and loss. RLCD families further evolve via slippage and other mechanisms associated with repetitive sequences. As analogous types of secreted proteins are expressed in biomineralizing tissues in other animals, insights into the evolution of the genes underlying molluscan shell formation may be applied more broadly to understanding the evolution of metazoan biomineralization.
    Keywords: Biomineralization; Mollusc; Mantle; Shell; Shell matrix proteins; Co-option; Lineage-specific novelties; Repetitive low complexity domain ; 551
    Language: English , English
    Type: article , publishedVersion
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  • 2
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    Variation in rates of early development in Haliotis asinina generate competent larvae of different ages (2018)
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    Publication Date: 2021-03-29
    Description: Introduction Inter-specific comparisons of metazoan developmental mechanisms have provided a wealth of data concerning the evolution of body form and the generation of morphological novelty. Conversely, studies of intra-specific variation in developmental programs are far fewer. Variation in the rate of development may be an advantage to the many marine invertebrates that posses a biphasic life cycle, where fitness commonly requires the recruitment of planktonically dispersing larvae to patchily distributed benthic environments. Results We have characterised differences in the rate of development between individuals originating from a synchronised fertilisation event in the tropical abalone Haliotis asinina, a broadcast spawning lecithotrophic vetigastropod. We observed significant differences in the time taken to complete early developmental events (time taken to complete third cleavage and to hatch from the vitelline envelope), mid-larval events (variation in larval shell development) and late larval events (the acquisition of competence to respond to a metamorphosis inducing cue). We also provide estimates of the variation in maternally provided energy reserves that suggest maternal provisioning is unlikely to explain the majority of the variation in developmental rate we report here. Conclusions Significant differences in the rates of development exist both within and between cohorts of synchronously fertilised H. asinina gametes. These differences can be detected shortly after fertilisation and generate larvae of increasingly divergent development states. We discuss the significance of our results within an ecological context, the adaptive significance of mechanisms that might maintain this variation, and potential sources of this variation.
    Description: Open-Access-Publikationsfonds 2012
    Keywords: 551
    Language: English
    Type: article , publishedVersion
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  • 3
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    A rapidly evolving secretome builds and patterns a sea shell (2018)
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    Publication Date: 2021-04-25
    Description: Background: Instructions to fabricate mineralized structures with distinct nanoscale architectures, such as seashells and coral and vertebrate skeletons, are encoded in the genomes of a wide variety of animals. In mollusks, the mantle is responsible for the extracellular production of the shell, directing the ordered biomineralization of CaCO3 and the deposition of architectural and color patterns. The evolutionary origins of the ability to synthesize calcified structures across various metazoan taxa remain obscure, with only a small number of protein families identified from molluskan shells. The recent sequencing of a wide range of metazoan genomes coupled with the analysis of gene expression in non-model animals has allowed us to investigate the evolution and process of biomineralization in gastropod mollusks.Results: Here we show that over 25% of the genes expressed in the mantle of the vetigastropod Haliotis asinina encode secreted proteins, indicating that hundreds of proteins are likely to be contributing to shell fabrication and patterning. Almost 85% of the secretome encodes novel proteins; remarkably, only 19% of these have identifiable homologues in the full genome of the patellogastropod Lottia scutum. The spatial expression profiles of mantle genes that belong to the secretome is restricted to discrete mantle zones, with each zone responsible for the fabrication of one of the structural layers of the shell. Patterned expression of a subset of genes along the length of the mantle is indicative of roles in shell ornamentation. For example, Has-sometsuke maps precisely to pigmentation patterns in the shell, providing the first case of a gene product to be involved in molluskan shell pigmentation. We also describe the expression of two novel genes involved in nacre (mother of pearl) deposition.
    Keywords: 551 ; VU 000
    Language: English
    Type: article , publishedVersion
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  • 4
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    Dynamic expression of ancient and novel molluscan shell genes during ecological transitions (2018)
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    Publication Date: 2021-04-25
    Description: Background: The Mollusca constitute one of the most morphologically and ecologically diverse metazoan phyla, occupying a wide range of marine, terrestrial and freshwater habitats. The evolutionary success of the molluscs can in part be attributed to the evolvability of the external shell. Typically, the shell first forms during embryonic and larval development, changing dramatically in shape, colour and mineralogical composition as development and maturation proceeds. Major developmental transitions in shell morphology often correlate with ecological transitions (e.g. from a planktonic to benthic existence at metamorphosis). While the genes involved in molluscan biomineralisation are beginning to be identified, there is little understanding of how these are developmentally regulated, or if the same genes are operational at different stages of the mollusc's life. Results: Here we relate the developmental expression of nine genes in the tissue responsible for shell production the mantle to ecological transitions that occur during the lifetime of the tropical abalone Haliotis asinina (Vetigastropoda). Four of these genes encode evolutionarily ancient proteins, while four others encode secreted proteins with little or no identity to known proteins. Another gene has been previously described from the mantle of another haliotid vetigastropod. All nine genes display dynamic spatial and temporal expression profiles within the larval shell field and juvenile mantle. Conclusion: These expression data reflect the regulatory complexity that underlies molluscan shell construction from larval stages to adulthood, and serves to highlight the different ecological demands placed on each stage. The use of both ancient and novel genes in all stages of shell construction also suggest that a core set of shell-making genes was provided by a shared metazoan ancestor, which has been elaborated upon to produce the range of molluscan shell types we see today.
    Keywords: 551 ; WJ 000 ; WK 000
    Language: English
    Type: article , publishedVersion
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  • 5
    Electronic Resource
    Electronic Resource
    Local and average interphase heat transfer coefficients in a randomly packed bed of spheres (1968)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 483-490 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Local and average heat transfer coefficients have been measured for a sphere in a randomly packed bed. A steady state technique was employed in which internally heated spheres were placed in a bed 35 in. deep and 12 in. sq. Air passed through the bed in downflow, the range of Reynolds numbers being from 120 to 1,700 based on the sphere diameter and the superficial velocity.Average heat transfer coefficients have been measured at twenty-five positions permitting the assessment of the effect of position. An entrance region limited to the first two particle layers in the bed has been verified.Distributions of the local heat transfer coefficient on the surface of a single sphere in the top layer and in the nineteenth layer of the bed have also been measured. These distributions indicate that a laminar boundary layer exists over portions of the sphere surface.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690140326
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  • 6
    Electronic Resource
    Electronic Resource
    The role of the institution of chemical engineers in international safety (1984)
    New York, NY : Wiley-Blackwell
    Plant/Operations Progress 3 (1984), S. 63-66 
    Details
    ISSN: 0278-4513
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prsb.720030203
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