Dynamic expression of ancient and novel molluscan shell genes during ecological transitions
© Jackson et al; licensee BioMed Central Ltd. 2007
Received: 22 December 2006
Accepted: 10 September 2007
Published: 10 September 2007
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.
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.
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.
The evolutionary success of certain major metazoan groups, such as the Mollusca, Bryozoa, Scleractinia, Echinodermata and Crustacea partly can be attributed to an ability to assemble a wide diversity of mineralised structures [1, 2]. This capacity, in combination with environmental changes at the end of the Proterozoic [3, 4], has been proposed as one of the biological characters that aided the Cambrian radiation . However, it is unknown if the genetic programming directing the biofabrication of calcified and other mineralised structures in disparate animals is homologous . This is because the molecular and cellular mechanisms underlying metazoan biomineralisation remain largely unknown (however see  for an example of a highly conserved biomineralisation gene). Further complicating this analysis is the fact that many animals with calcified skeletons produce different types of skeletons at different times in their lives, with marked changes in skeletal form, mineralogy and function often accompanying ecological transitions . For example, most marine invertebrates have pelagobenthic life cycles, where metamorphosis of the microscopic larva into a benthic juvenile dramatically changes the ecology and body plan of the animal. This major ecological and morphological transition often includes a dramatic change in the form and function of the molluscan shell. It is currently unknown if ontogenetic changes in skeletal construction are the result of the expression of different batteries of biomineralisation genes, i.e. are discrete genetic networks required for larval shell formation versus adult shell formation?
All shell bearing molluscs employ a homologous organ (the mantle) to construct their shells in a way that permits an amazing phenotypic diversity . The mantle consists of a variety of cell types that are directly responsible for synthesis of the shell via the secretion of an organic matrix that is able to initiate and regulate the cell-autonomous assembly of CaCO3 crystals . Once initiated upon synthetic substrates in vitro, ordered CaCO3 crystal growth can reflect that observed in vivo [10, 11]. A number of proteins implicated in the calcification process have been identified from the shells of mature animals including oysters [12–14], mussels [15–17] and abalone [11, 18–20]. Despite the formulation of detailed hypotheses regarding the molecular basis of molluscan shell formation [21–24], these do not account for the initiation of biomineralisation or changes in shell construction during a mollusc's life [see  for a review of the mineralogical transitions that occur in larval forms]. Currently, only a handful of genes are known to play a role in the larval stages of biomineralisation [26–30], with all of these encoding molecules that either define biomineralising cells, the boundaries between biomineralising and non-biomineralising fields, or act to regulate the expression of downstream actuators of the biomineralisation process.
Here, we investigate the ontogenetic expression of a suite of genes expressed in shell forming cells and tissues in the tropical abalone Haliotis asinina. The juvenile mantle of H. asinina expresses a diverse set of genes, a large proportion of which are evolutionarily novel, are predicted to be secreted and are likely to be directly involved in shell synthesis . The regionalised structure of the juvenile mantle and shell also allows inferences to be made regarding gene function . Here we describe the developmental expression of nine mantle genes during the life of H. asinina, specifically testing if ontogenetic changes in gene expression correlate with ecological and morphological transitions. These genes are all expressed in dynamic patterns in shell forming cells and tissues, revealing the complexity of the genetic network underlying molluscan skeletogenesis. These results serve to highlight the interplay between ecology, evolution and development that has shaped the diversity of molluscan shells we see today.
Temporal expression of biomineralising genes
Gene characterisation and spatial expression
We recently have shown that the juvenile Haliotis asinina mantle transcriptome is rapidly evolving and extremely complex . It is evident that hundreds of proteins are secreted from the gastropod mantle into the vicinity where biomineralisation occurs. These are likely to be involved in shell synthesis, presumably contributing directly to the patterning and construction of the calcified shell. The regulation and production of the abalone shell is at least an order more complex than has been inferred from a compilation of previous studies on shell matrix proteins in numerous other molluscs as acknowledged by Marin and Luquet . This 'secretome' complexity, in combination with the modular organisation of the mantle into distinct territories responsible for the biofabrication of discrete shell layers [31, 40], provides a foundation for the generation of diverse shell types. While we cannot yet provide functional data for any of the genes we have studied here, based on their expression profiles we can infer another level of complexity in the regulation of these shell genes at different life cycle stages. The temporal regulation of biomineralisation genes is likely to be an important factor in the production of ontogenetically discrete shell types. For H. asinina, ontogenetic changes in the expression of genes likely to be directly involved in the process of biomineralisation correlate with habitat and ecological transitions.
Changes in shell structure and pattern track with H. asinina's ecology
H. asinina has a pelagobenthic life cycle that includes a minimal period of three to four days in the plankton [33, 41]. The first biomineralisation events occur shortly after hatching, with the fabrication of the larval shell (protoconch) over about a 10 h period. These structures allow the veliger larva to completely retract into a protective environment and rapidly fall out of the water column. The next phase of biomineralisation does not commence until the competent veliger larva contacts an environmental cue that induces metamorphosis . Postlarval shell (teleoconch) is laid down rapidly following metamorphosis with marked variation in the rate of its production between individuals. While the initial teloconch is not pigmented (Fig. 1D), it is textured and opaque such that postlarval shell growth is easily discerned from the larval shell (Fig. 1D inset). Subsequently, the teloconch rapidly develops a uniform maroon colouration similar to the crustose coralline algae (CCA) that the larva has settled upon (Fig. 1E). At about 1 mm in size further changes in the morphogenetic program of the mantle are reflected in the shell. Structurally, a pronounced series of ridges and valleys and a line of respiratory pores (tremata) have appeared (Fig. 1F). Furthermore, it is at this stage of development that the first recognisable tablets of nacre can be detected (Fig. 1J). Colourmetrically, the uniform maroon background is now interrupted by oscillations of a pale cream colour, and is punctuated by a pattern of dots (that only occur on ridges) which are blue when overlying a maroon field and orange when overlying a cream field. This shell pattern may enhance the juvenile's ability to camouflage on the heterogeneous background of the CCA they inhabit at this stage of development.
At 10 to 15 mm, this ornate colouration pattern begins to fade, with maroon and cream fields apparently blending to give a brown background. Blue and orange dots however persist on the ridges (Fig. 1G). With further growth, the ridge-valley structure fades to give rise to a smooth adult shell, with irregular brown-green triangles on a light brown background (Fig. 1H). These larger animals are nocturnal, graze amongst turf algae  and inhabit the undersides of boulders and coral bommies . Overall, ontogenetic changes in H. asinina shell pigmentation and structure match changes in the habitats occupied during development.
Differential expression of mantle genes reflect changes in shell structure
The spatial and temporal expression patterns of the nine genes investigated here reveal a complexity to the genetic networks that coordinate the deposition of larval, juvenile and adult shell. Many of the genes analysed in this study are expressed in the mantle during the production of larval, juvenile and adult shells (Has-Ubfm, Has-ferrt, Has-calmbp1), while others are restricted to one or two shell phases (Has-tsfgr1, Has-cam1, Has-vm1, Has-vm2, Has-lustA, Has-Som). While the lack of a detailed cell fate map through metamorphosis prevents conclusions from being drawn regarding cellular developmental homologies, the continuous expression of Has-tsfgr1 and Has-vm1 in cells no other than shell forming cells in both larval and postlarval stages suggests that a proportion of the postlarval mantle is derived from cells of the larval shell field.
Analyses of the expression profiles of the genes included in this study provide insight into the morphogenetic activity of shell production at different stages in the life of H. asinina. Genes that are continuously expressed in the mantle – Has-ferrt, Has-ubfm and Has-calmbp1 – are likely to play fundamental roles in biomineralisation. Has-ubfm encodes a highly conserved ubiquitin fold-like modifying protein  and is expressed in the expanding shell field suggests that specific intracellular processing of gene products is required to generate functional extracellular components of the biomineralising secretome. Two other evolutionarily conserved proteins, Has-ferrt and Has-calmbp1, are also expressed within the trochophore shell field and later in the mantle, and also are likely to be involved in intracellular events necessary for shell deposition. Iron is known to affect calcification processes in mammals [44, 45], algae  and molluscs . The high expression level of Has-ferrt in a range of cell types in the juvenile mantle is compatible with iron being essential for shell construction or pigmentation. Has-calmbp1 is similar to calcium dependent protein kinases, however its role in shell production remains unknown.
In contrast to these constitutively expressed genes, Has-tsfgr1 displays a dynamic expression profile in the shell forming tissue during development. The putative protein is composed of a set of glycine-rich repeats (over 52% Gly in the mature protein), suggesting it may possess elastomeric properties known to be important in various calcification processes . The highly repetitive nature of Has-tsfgr1 also suggests that this protein may be involved in forming the organic template upon which initial CaCO3 nucleation occurs . Recently Yano et al.  isolated a family of glycine rich, repetitive motif proteins (Shematrins) from a mantle cDNA library of the pearl oyster Pinctada fucata. The Shematrin family is currently known to encode 7 proteins with similar C-terminal motifs which terminate in a tyrosine residue and are expressed in the mantle edge, apparently localised to the prismatic layer of the mature oyster shell . Interestingly, Has-tsfgr1 also possesses a C-terminal motif of 5 residues terminating in a tyrosine residue, suggesting that this feature may be of functional importance to this class of protein. Although sequence alignments of the Shematrins and Has-tsfgr1 do not reveal any close sequence homology, the high glycine content, repetitive nature and shared spatial expression suggest these proteins may play similar functional roles. Unlike Has-ubfm, Has-calmbp1, and Has-ferrt, which all maintain expression within juvenile and adult mantle tissue, Has-tsfgr1 is significantly down-regulated in the mantle tissue of >20 mm animals. This observation is compatible with different stages of shell development requiring the secretion of discrete sets of structural proteins, which act to alter the physical and mineralogical characteristics of the shell.
Two other novel genes – Has-vm1 and -vm2 – also display a dynamic temporal expression during the development of the shell. As expression of Has-vm1 is activated in the larval mantle after completion of the construction of the larval shell, this gene is likely to be involved in the construction of the postlarval shell following metamorphosis. This pattern of expression reveals a linkage between larval and postlarval mantles and is similar to that observed for the developmental regulator Has-Hox4 . It also demonstrates that although larval shell synthesis has ceased, transcriptional activity in the larval mantle continues in anticipation for the next life cycle phase .
Has-vm2 is also differentially regulated during shell growth, and encodes a protein with the hallmarks of being involved in biomineralisation including a signal sequence, repetitive proline rich motifs and two putative O-linked glycosylation sites. Has-vm2 is also down-regulated in larger individuals, with a concomitant reduction in transcript size suggesting that alternative splicing of this gene product takes place in animals larger than 40 mm, again highlighting the different requirements for shell construction at different life cycle stages.
Three genes – Has-cam, Has-lustA and Has-Som – are expressed in patterns that are indicative of roles in biomineralisation during post-larval shell growth. Reflective of the various roles it plays within well studied mammalian systems including signal transduction and regulation of the cell cycle [50–53], Has-cam1 appears to play diverse roles during development. Highly expressed in the prototroch of trochophores, it is not until the veliger larva attains competence to metamorphose that Has-cam1 is detected within the mantle. This suggests that Has-cam1 is not directly involved in larval shell synthesis. In agreement with studies on bivalves [12, 54]Has-cam1 is expressed within the gills and the outer fold of the mantle of juvenile animals. The expression pattern of Has-lustA supports its proposed role of binding aragonitic tablets of nacre together [18, 55], and coincides with the appearance of ordered aragonitic tablets. Interestingly, Has-lustA is down-regulated in the mantle tissue of mature abalone of 100 mm (Fig. 2) possibly reflecting a cessation of shell growth as this is close to the maximum size of 11 cm reported for this species . Has-Som has previously been shown to play a role in pigmentation of the juvenile shell  and is expressed in the mantle tissue of juvenile animals at the time complex colour patterning commences.
Many planktonic molluscan larvae face similar challenges during larval life and the evolution of a larval shell has clearly been a successful response to these challenges . On the molecular level, it is currently unknown the degree to which construction of the molluscan protoconch is conserved. Previous studies have revealed that the expression of the engrailed transcription factor in polyplacophoran , gastropod [27, 29, 57] and scaphopod  representatives is restricted to cells that form boundaries between shell forming and non-shell forming ectoderm, suggesting that the regulatory mechanisms that establish shell forming structures in these clades were inherited from a common ancestor. Following metamorphosis, planktonic molluscan larvae inhabit a broad diversity of benthic ecological niches from sediments, coral reefs, deep sea hydrothermal vents and temperate rocky reefs. The shell of the tropical abalone undergoes several major transitions in morphology, mineralogy and pigmentation during its construction, each of which is adapted to suit the different habitats that larval, juvenile and adult forms occupy. These varied morphologies are the result of differential gene expression of both evolutionarily ancient and novel genes within the mantle tissue.
Given the number of reports of molluscan biomineralising genes that do not share homology with any other phyla (see  for a review) and the data reported here, we suggest that the rapid evolution of the mantle secretome has greatly contributed to the radiation and evolutionary success of the Mollusca . This study demonstrates that the regulation of these genes can be complex, with different batteries of structural genes activated in different parts of the mantle at different phases of the life cycle. We show that changes in expression correlate with changes in shell structure, colour and pattern, and that these changes map closely with ecological transitions. We propose that the regulation of this rapidly evolving mantle secretome is achieved through the action of highly conserved transcription factors and signalling molecules. Dissection of the gene regulatory networks controlling the construction of both larval and postlarval shells promises to shed light on the interplay between ecology and development on evolution of the molluscan body plan.
Analysis of mantle genes
The genes investigated in this study were originally identified either through (1) an expressed sequence tag (EST) screen of genes expressed in the mantle of juvenile abalone , (2) an EST survey of developmentally expressed genes  or (3) a differential display analysis of developmentally regulated genes . Full length cDNA sequences for the genes used in this study were obtained using a RACE approach as described in Jackson et al. . cDNA sequences were initially characterised as described in Jackson et al.  and classified as either having conceptually derived amino acid sequence similarity with proteins in public databases, or encoding a novel secreted protein. The presence of signal peptides was inferred using the SignalP 3.0 server  and glycosylation predictions were made using the NetOGlyc server . Putative open reading frames (ORFs) for the evolutionarily novel and divergent genes Has-vm1 (H. as inina – v eliger m antle 1), Has-vm2 (veliger mantle 2), Has-tsfgr1 (trochophore shell field glycine rich 1) and Has-Som (Sometsuke) were identified using ORF Finder .
For genes encoding conserved proteins (Has-ubfm, ubiquitin fold modifier; Has-cam1, calmodulin; Has-ferrt, ferritin; Has-calmbp1, calcium binding protein; Has-lustA, Lustrin A), tBLASTx and BLASTp searches were conducted against the GenBank database using default settings (Has-Som, Sometsuke, has been previously characterised ). Publicly available protein sequences that displayed significant similarity to H. asinina sequences and representing a broad taxonomic range were downloaded and aligned in ClustalX. Alignments were manually edited in MacClade. Percent identity and biochemical similarity for each sequence relative to the respective H. asinina sequence were calculated using the NCBI bl2seq algorithm .
Animals and whole mount in situ hybridisation
Animals were procured from natural spawnings conducted at the Bribie Island Aquaculture Research Centre, Queensland, Australia as described in Jackson et al. . Larvae and juvenile abalone were relaxed in approximately 0.3 M MgCl2 in FSW prior to fixation in 4% paraformaldehyde in 0.1 M 3-(N-morpholino) propane sulfonic acid pH 7.5 (MOPS), 2 mM MgSO4, 1 mM ethyleneglycoltetraacetic acid (EGTA) and 0.5 M sodium chloride (NaCl) for 30 min at room temperature. Fixed samples were then rinsed several times with PBS buffer plus 0.1% Tween 20 and stepped into 75% ethanol and stored at -20°C. Decalcification of the juvenile shell was achieved by incubation in a solution of 4% paraformaldehyde, 1× PBS buffer and 350 mM ethylenediaminetetraacetic acid (EDTA) for 1 – 3 h depending on shell size. The remaining periostracum and proteinaceous components of the shell were manually dissected away from the animal with fine dissecting forceps. Whole mount in situ hybridisation using digoxigenin-labeled riboprobes synthesised from PCR templates was performed following Giusti et al.  and Jackson et al. .
Reverse transcriptase PCR
Total RNA was extracted from eggs, 10 h old newly hatched trochophores, 134 h old competent veligers, whole 4 mm (shell length) juveniles, 20 mm juvenile mantle tissue, 40 mm juvenile mantle tissue and 100 mm adult mantle tissue using TriReagent following the manufactures instructions. cDNA was synthesised from 1 μg of intact total RNA following Jackson et al. . Relative levels of gene expression across the 7 cDNA samples were assessed by empirically determining the linear phase of PCR amplification for each gene using gene specific primers (available upon request). Briefly, each PCR was run for 20 cycles after which time 4 μl was removed. Reactions were then allowed to continue for a further 3 cycles and the process repeated until aliquots had been obtained from cycles 20 – 34. Samples were then separated on 2% agarose gels . Each PCR reaction was run in duplicate with cDNA synthesised in the absence of MMLV-RT as a control for genomic DNA contamination. Histone H1 was used as a constitutively expressed housekeeping gene and as an indicator of equivalent cDNA synthesis efficiency and PCR template quality [33, 65].
Scanning electron microscopy
Nine, 10 and 11 h old trochophores were fixed in 3% glutaraldehyde in 0.1 M sodium cacodylate buffer for 30 min then washed in the same buffer prior to postfixing in 1% osmium tetroxide (OsO4) in 0.1 M sodium cacodylate buffer. Samples were dehydrated through a graded series of ethanol before being infiltrated and dried overnight in hexamethyldisilasane (HMDS). The soft tissue of competent veligers and newly metamorphosed post-larvae was dissolved using 2.8% v/v sodium hypochlorite for approximately 5 min. The remaining shells were then washed extensively with de-ionised water and dehydrated with 100% ethanol before mounting. All samples were mounted either on double-sided tape or Leit-C conductive carbon cement on aluminium stubs and sputter-coated with gold. Samples were viewed with an S-2300 Hitachi scanning electron microscope at 10 kV.
- Has-ubfm :
Haliotis asinina Ubiquitin fold modifier 1
- Hasferrt :
Haliotis asinina ferritin
- Has-calmbp1 :
Haliotis asinina calcium binding protein 1
- Has-tsfgr1 :
Haliotis asinina trochophore shell field glycine rich 1
- Has-Cam1 :
Haliotis asinina calmodulin 1
- Has-vm1 :
Haliotis asinina veliger mantle 1
- Has-vm2 :
Haliotis asinina veliger mantle 2
- HaslustA :
Haliotis asinina lustrinA
- Has-Som :
Haliotis asinina sometsuke
We are grateful to Kathryn Green for the trochophore SEM and Andreas Reimer for SEM advice. Alina Craigie and Elizabeth Williams provided the in situ image shown in Fig. 7E. Andreas Wanninger provided valuable discussions, which greatly improved this manuscript. Two anonymous reviewers provided valuable comments. This work was supported by Australian Research Council funds to BMD and German Research Foundation funds (DFG, Project Wo896/4-1 COSMAP) to GW.
- Weiner S, Dove PM: An overview of biomineralization processes and the problem of the vital effect. Biomineralization. Edited by: Dove PM, De Yoreo JJ, Weiner S. 2003, Washington, DC , Mineralogical Society of America, 54: 1-29.Google Scholar
- Lowenstam HA, Weiner S: On Biomineralization. 1989, Oxford , Oxford University Press, 324-Google Scholar
- Brennan ST, Lowenstein TK, Horita J: Seawater chemistry and the advent of biocalcification. Geology. 2004, 32 (6): 473-476. 10.1130/G20251.1.View ArticleGoogle Scholar
- Feng W, W. S: Phosphate replicated and replaced microstructure of molluscan shells from the earliest Cambrian of China. Acta Paleo Pol. 2003, 48 (1): 21-30.Google Scholar
- Knoll AH: Biomineralization and evolutionary history. Rev Mineral Geochem. 2003, 54 (1): 329-356. 10.2113/0540329.View ArticleGoogle Scholar
- Jackson DJ, Macis L, Degnan B, Wörheide G: Sponge paleogenetics reveals an ancient role for carbonic anhydrase in skeletogenesis. Science. 2007, 316: 1893-1895. 10.1126/science.1141560.View ArticlePubMedGoogle Scholar
- Brusca RC, Brusca GJ: Invertebrates. 2002, Sinauer, SecondGoogle Scholar
- Abbott RT, Dance SP: Compendium of seashells: a full-color guide to more than 4,200 of the world's marine shells. 1998, El Cajon, California , Odyssey Publishing, 411-Google Scholar
- Zaremba CM, Belcher AM, Fritz M, Li YL, Mann S, Hansma PK, Morse DE, Speck JS, Stucky GD: Critical transitions in the biofabrication of abalone shells and flat pearls. Chem Mater. 1996, 8 (3): 679-690. 10.1021/cm9503285.View ArticleGoogle Scholar
- Thompson JB, Paloczi GT, Kindt JH, Michenfelder M, Smith BL, Stucky G, Morse DE, Hansma PK: Direct observation of the transition from calcite to aragonite growth as induced by abalone shell proteins. Biophys J. 2000, 79 (6): 3307-3312.PubMed CentralView ArticlePubMedGoogle Scholar
- Fu G, Valiyaveettil S, Wopenka B, Morse DE: CaCO3 biomineralization: acidic 8-kDa proteins isolated from aragonitic abalone shell nacre can specifically modify calcite crystal morphology. Biomacromolecules. 2005, 6 (3): 1289-1298. 10.1021/bm049314v.View ArticlePubMedGoogle Scholar
- Li S, Xie LP, Ma ZJ, Zhang RQ: cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata. Febs Journal. 2005, 272 (19): 4899-4910. 10.1111/j.1742-4658.2005.04899.x.View ArticlePubMedGoogle Scholar
- Zhang Y, Meng QX, Jiang TM, Wang HZ, Xie LP, Zhang RQ: A novel ferritin subunit involved in shell formation from the pearl oyster (Pinctada fucata). Comp Biochem Physiol B. 2003, 135 (1): 43-54.View ArticlePubMedGoogle Scholar
- Yano M, Nagai K, Morimoto K, Miyamoto H: Shematrin: A family of glycine-rich structural proteins in the shell of the pearl oyster Pinctada fucata. Comp Biochem Physiol B. 2006, 144 (2): 254-262. 10.1016/j.cbpb.2006.03.004.View ArticlePubMedGoogle Scholar
- Marin F, Amons R, Guichard N, Stigter M, Hecker A, Luquet G, Layrolle P, Alcaraz G, Riondet C, Westbroek P: Caspartin and calprismin, two proteins of the shell calcitic prisms of the Mediterranean fan mussel Pinna nobilis. J Biol Chem. 2005, 280 (40): 33895-33908. 10.1074/jbc.M506526200.View ArticlePubMedGoogle Scholar
- Marin F, Corstjens P, de Gaulejac B, de Vrind-De Jong E, Westbroek P: Mucins and Molluscan Calcification. Molecular characterization of mucoperlin, a novel mucin-like protein from the nacreous shell layer of the fan mussel Pinna nobilis (bivalvia, pteriomorphia). J Biol Chem. 2000, 275 (27): 20667-20675. 10.1074/jbc.M003006200.View ArticlePubMedGoogle Scholar
- Marin F, Luquet G: Molluscan biomineralization: The proteinaceous shell constituents of Pinna nobilis L. Mat Sci Eng C. 2005, 25 (2): 105-111. 10.1016/j.msec.2005.01.003.View ArticleGoogle Scholar
- Shen XY, Belcher AM, Hansma PK, Stucky GD, Morse DE: Molecular cloning and characterization of lustrin A, a matrix protein from shell and pearl nacre of Haliotis rufescens. J Biol Chem. 1997, 272 (51): 32472-32481. 10.1074/jbc.272.51.32472.View ArticlePubMedGoogle Scholar
- Weiss IM, Gohring W, Fritz M, Mann K: Perlustrin, a Haliotis laevigata (Abalone) nacre protein, is homologous to the insulin-like growth factor binding protein N-terminal module of vertebrates. Biochem Biophys Res Comm. 2001, 285 (2): 244-249. 10.1006/bbrc.2001.5170.View ArticlePubMedGoogle Scholar
- Mann K, Weiss IM, Andre S, Gabius HJ, Fritz M: The amino-acid sequence of the abalone (Haliotis laevigata) nacre protein perlucin. Detection of a functional C-type lectin domain with galactose/mannose specificity. Eur J Biochem. 2000, 267 (16): 5257-5264. 10.1046/j.1432-1327.2000.01602.x.View ArticlePubMedGoogle Scholar
- Lowenstam HA, Weiner S: On biomineralization. 1989, New York; Oxford , Oxford University Press, 324-Google Scholar
- Falini G, Fermani S: Chitin mineralization. Tissue Engineering. 2004, 10 (1/2): 1-6. 10.1089/107632704322791646.View ArticlePubMedGoogle Scholar
- Schaffer TE, IonescuZanetti C, Proksch R, Fritz M, Walters DA, Almqvist N, Zaremba CM, Belcher AM, Smith BL, Stucky GD, Morse DE, Hansma PK: Does abalone nacre form by heteroepitaxial nucleation or by growth through mineral bridges?. Chem Mater. 1997, 9 (8): 1731-1740. 10.1021/cm960429i.View ArticleGoogle Scholar
- Estroff LA, Addadi L, Weiner S, Hamilton AD: An organic hydrogel as a matrix for the growth of calcite crystals. Org Biomol Chem. 2004, 2 (1): 137-141. 10.1039/b309731e.View ArticlePubMedGoogle Scholar
- Addadi L, Raz S, Weiner S: Taking advantage of disorder: Amorphous calcium carbonate and its roles in biomineralization. Adv Mat. 2003, 15 (12): 959-970. 10.1002/adma.200300381.View ArticleGoogle Scholar
- Wanninger A, Haszprunar G: The expression of an engrailed protein during embryonic shell formation of the tusk-shell, Antalis entalis (Mollusca, Scaphopoda). Evol Dev. 2001, 3 (5): 312-321. 10.1046/j.1525-142X.2001.01034.x.View ArticlePubMedGoogle Scholar
- Moshel SM, Levine M, Collier JR: Shell differentiation and engrailed expression in the Ilyanassa embryo. Dev Genes Evo. 1998, 208 (3): 135-141. 10.1007/s004270050164.View ArticleGoogle Scholar
- Jacobs DK, Wray CG, Wedeen CJ, Kostriken R, DeSalle R, Staton JL, Gates RD, Lindberg DR: Molluscan engrailed expression, serial organization, and shell evolution. Evol Dev. 2000, 2 (6): 340-347. 10.1046/j.1525-142x.2000.00077.x.View ArticlePubMedGoogle Scholar
- Nederbragt AJ, van Loon AE, Dictus W: Expression of Patella vulgata orthologs of engrailed and dpp-BMP2/4 in adjacent domains during molluscan shell development suggests a conserved compartment boundary mechanism. Dev Biol. 2002, 246 (2): 341-355. 10.1006/dbio.2002.0653.View ArticlePubMedGoogle Scholar
- Hinman VF, O'Brien EK, Richards GS, Degnan BM: Expression of anterior Hox genes during larval development of the gastropod Haliotis asinina. Evol Dev. 2003, 5 (5): 508-521. 10.1046/j.1525-142X.2003.03056.x.View ArticlePubMedGoogle Scholar
- Jackson DJ, McDougall C, Green KM, Simpson F, Wörheide G, Degnan BM: A rapidly evolving secretome builds and patterns a sea shell. BMC Biol. 2006, 4 (40):
- Kniprath E: Ontogeny of the molluscan shell field - a review. Zool Scripta. 1981, 10 (1): 61-79. 10.1111/j.1463-6409.1981.tb00485.x.View ArticleGoogle Scholar
- Jackson DJ, Ellemor N, Degnan BM: Correlating gene expression with larval competence, and the effect of age and parentage on metamorphosis in the tropical abalone Haliotis asinina. Mar Biol. 2005, 147: 681-697. 10.1007/s00227-005-1603-z.View ArticleGoogle Scholar
- Morse DE, Hooker N, Duncan H, Jensen L: g-aminobutyric acid, a neurotransmitter, induces planktonic abalone larvae to settle and begin metamorphosis. Science. 1979, 204: 407-410. 10.1126/science.204.4391.407.View ArticlePubMedGoogle Scholar
- Komatsu M, Chiba T, Tatsumi K, Iemura S, Tanida I, Okazaki N, Ueno T, Kominami E, Natsume T, Tanaka K: A novel protein-conjugating system for Ufm1, a ubiquitin-fold modifier. EMBO J. 2004, 23 (9): 1977-1986. 10.1038/sj.emboj.7600205.PubMed CentralView ArticlePubMedGoogle Scholar
- Gatesy J, Hayashi C, Motriuk D, Woods J, Lewis R: Extreme Diversity, Conservation, and Convergence of Spider Silk Fibroin Sequences. Science. 2001, 291 (5513): 2603-2605. 10.1126/science.1057561.View ArticlePubMedGoogle Scholar
- van Beek JD, Hess S, Vollrath F, Meier BH: From the Cover: The molecular structure of spider dragline silk: Folding and orientation of the protein backbone. PNAS. 2002, 99 (16): 10266-10271. 10.1073/pnas.152162299.PubMed CentralView ArticlePubMedGoogle Scholar
- Trace archive. [http://www.ncbi.nlm.nih.gov/Traces/trace.cgi?]
- Marin F, Luquet G: Molluscan shell proteins. Comptes Rendus Palevol. 2004, 3 (6-7): 469-492. 10.1016/j.crpv.2004.07.009.View ArticleGoogle Scholar
- Jolly C, Berland S, Milet C, Borzeix S, Lopez E, Doumenc D: Zonal localization of shell matrix proteins in mantle of Haliotis tuberculata (Mollusca, Gastropoda). Mar Biotechnol. 2004, 6 (6): 541-551. 10.1007/s10126-004-3129-7.View ArticlePubMedGoogle Scholar
- Jackson DJ, Leys SP, Hinman VF, Woods R, Lavin MF, Degnan BM: Ecological regulation of development: induction of marine invertebrate metamorphosis. Int J Dev Biol. 2002, 46: 679-686.PubMedGoogle Scholar
- McNamara DC, Johnson CR: Growth of the ass's ear abalone (Haliotis asinina Linne) on Heron Reef, tropical eastern Australia. Mar Fresh Res. 1995, 46 (3): 571-574. 10.1071/MF9950571.View ArticleGoogle Scholar
- Counihan RT, McNamara DC, Souter DC, Jebreen EJ, Preston NP, Johnson CR, Degnan BM: Pattern, synchrony and predictability of spawning of the tropical abalone Haliotis asinina from Heron Reef, Australia. Mar Ecol Prog Ser. 2001, 213: 193-202. 10.3354/meps213193.View ArticleGoogle Scholar
- Gabbiani G, Tuchweber B: The role of iron in the mechanism of experimental calcification. J Histochem Cytochem. 1963, 11 (6): 799-803.View ArticleGoogle Scholar
- Anghileri LJ, Maincent P, Cordovamartinez A: On the mechanism of soft-tissue calcification induced by complexed iron. Exp Toxicol Path. 1993, 45 (5-6): 365-368.View ArticleGoogle Scholar
- Schulz KG, Zondervan I, Gerringa LJA, Timmermans KR, Veldhuis MJW, Riebesell U: Effect of trace metal availability on coccolithophorid calcification. Nature. 2004, 430 (7000): 673-676. 10.1038/nature02631.View ArticlePubMedGoogle Scholar
- Wustman BA, Santos R, Zhang B, Evans JS: Identification of a "glycine-loop"-like coiled structure in the 34 AA Pro,Gly,Met repeat domain of the biomineral-associated protein, PM27. Biopolymers. 2002, 65 (5): 362-372. 10.1002/bip.10274.View ArticlePubMedGoogle Scholar
- Addadi L, Joester D, Nudelman F, Weiner S: Mollusk shell formation: a source of new concepts for understanding biomineralization processes. Chem Eur J. 2006, 12 (4): 980-987. 10.1002/chem.200500980.View ArticlePubMedGoogle Scholar
- Degnan BM, Morse DE: Developmental and morphogenetic gene regulation in Haliotis rufescens larvae at metamorphosis. Am Zool. 1995, 35: 391-398.View ArticleGoogle Scholar
- Kawakami A, Tanaka F, Tamai M, Nakamura H, Iwanaga N, Izumi Y, Arima K, Aratake K, Kamachi M, Huang MG, Origuchi T, Ida H, Hagi K, Nishikaku F, Eguchi K: Calcium/calmodulin-dependent protein kinase II(Camkii) regulates apoptosis of synovial cells through the activation of Akt. Arthritis and Rheumatism. 2005, 52 (9): S575-S576.Google Scholar
- Vetter SW, Leclerc E: Novel aspects of calmodulin target recognition and activation. Eur J Biochem. 2003, 270: 404-414. 10.1046/j.1432-1033.2003.03414.x.View ArticlePubMedGoogle Scholar
- Wargo MJ, Dymek EE, Smith EF: Calmodulin and PF6 are components of a complex that localizes to the C1 microtubule of the flagellar central apparatus. J Cell Sci. 2005, 118 (20): 4655-4665. 10.1242/jcs.02585.View ArticlePubMedGoogle Scholar
- Beguin P, Mahalakshmi RN, Nagashima K, Cher DHK, Kuwamura N, Yamada Y, Seino Y, Beguin P: Roles of 14-3-3 and calmodulin binding in subcellular localization and function of the small G-protein Rem2. Biochem J. 2005, 390: 67-75. 10.1042/BJ20050414.PubMed CentralView ArticlePubMedGoogle Scholar
- Li S, Xie L, Zhang C, Zhang Y, Gu M, Zhang R: Cloning and expression of a pivotal calcium metabolism regulator: calmodulin involved in shell formation from pearl oyster (Pictada fucata). Comp Biochem Physiol B. 2004, 138 (138): 235-243. 10.1016/j.cbpc.2004.03.012.View ArticlePubMedGoogle Scholar
- Smith BL, Schaffer TE, Viani M, Thompson JB, Frederick NA, Kindt J, Belcher A, Stucky GD, Morse DE, Hansma PK: Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites. Nature. 1999, 399 (6738): 761-763. 10.1038/21607.View ArticleGoogle Scholar
- Hickman CS: Evolution and development of gastropod larval shell morphology: experimental evidence for mechanical defense and repair. Evol Dev. 2001, 3 (1): 18-23. 10.1046/j.1525-142x.2001.01003.x.View ArticlePubMedGoogle Scholar
- Jackson DJ, Degnan BM: EST analysis of genes expressed during development of the tropical abalone Haliotis asinina. J Shellfish Res. 2006, 25 (1): 225-View ArticleGoogle Scholar
- SignalP 3.0. [http://www.cbs.dtu.dk/services/SignalP/]
- NetOGlyc server. [http://www.cbs.dtu.dk/services/NetOGlyc/]
- ORF finder. [http://www.ncbi.nlm.nih.gov/gorf/orfig.cgi]
- NCBI bl2seq. [http://www.ncbi.nlm.nih.gov/blast/bl2seq/wblast2.cgi]
- Giusti AF, Hinman VF, Degnan SM, Degnan BM, Morse DE: Expression of a Scr/Hox5 gene in the larval central nervous system of the gastropod Haliotis, a non-segmented spiralian lophotrochozoan. Evol Dev. 2000, 2 (5): 294-302. 10.1046/j.1525-142x.2000.00071.x.View ArticlePubMedGoogle Scholar
- Sambrook J, Russell DW: Molecular cloning: a laboratory manual. 2001, Cold Spring Harbor, New York , Cold Spring Harbor Laboratory Press, 3Google Scholar
- Robert C, McGraw S, Massicotte L, Pravetoni M, Gandolfi F, Sirard MA: Quantification of Housekeeping Transcript Levels During the Development of Bovine Preimplantation Embryos. Biol Reprod. 2002, 67 (5): 1465-1472. 10.1095/biolreprod.102.006320.View ArticlePubMedGoogle Scholar
- Dawoud Al-Bader M, Ali Al-Sarraf H: Housekeeping gene expression during fetal brain development in the rat - validation by semi-quantitative RT-PCR. Dev Brain Res. 2005, 156 (1): 38-45. 10.1016/j.devbrainres.2005.01.010.View ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.