The Chiton Radula: A Model System for Versatile Use of Iron Oxides*

Joester, Derk; Brooker, L.R.

doi:10.1002/9783527691395.ch8

“…Chitons produce new teeth throughout their lives, making new rows within days ( Shaw et al. 2002 ; Joester and Brooker 2016 ). To make new teeth, chitons continuously sequester iron from their diet and circulate high concentrations of iron in their hemolymph ( Kim et al.…”

Section: Introductionmentioning

confidence: 99%

The Iron-Responsive Genome of the Chiton Acanthopleura granulata

Varney

¹

,

Speiser

²

,

McDougall

³

et al. 2020

Genome Biology and Evolution

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Molluscs biomineralize structures that vary in composition, form, and function, prompting questions about the genetic mechanisms responsible for their production and the evolution of these mechanisms. Chitons (Mollusca, Polyplacophora) are a promising system for studies of biomineralization because they build a range of calcified structures including shell plates and spine- or scale-like sclerites. Chitons also harden the calcified teeth of their rasp-like radula with a coat of iron (as magnetite). Here we present the genome of the West Indian fuzzy chiton Acanthopleura granulata, the first from any aculiferan mollusc. The A. granulata genome contains homologs of many genes associated with biomineralization in conchiferan molluscs. We expected chitons to lack genes previously identified from pathways conchiferans use to make biominerals like calcite and nacre because chitons do not use these materials in their shells. Surprisingly, the A. granulata genome has homologs of many of these genes, suggesting that the ancestral mollusc may have had a more diverse biomineralization toolkit than expected. The A. granulata genome has features that may be specialized for iron biomineralization, including a higher proportion of genes regulated directly by iron than other molluscs. A. granulata also produces two isoforms of soma-like ferritin: one is regulated by iron and similar in sequence to the soma-like ferritins of other molluscs, and the other is constitutively translated and is not found in other molluscs. The A. granulata genome is a resource for future studies of molluscan evolution and biomineralization.

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“…These iron coatings allow chitons to scrape algae from rocks without rapidly dulling or damaging their teeth. Chitons produce new teeth throughout their lives, making new rows within days (Shaw et al 2002; Joester & Brooker 2016). To make new teeth, chitons continuously sequester and transport high concentrations of iron (Kim et al 1989; Shaw et al 2002, 2010).…”

Section: Introductionmentioning

confidence: 99%

The iron-responsive genome of the chitonAcanthopleura granulata

Varney

¹

,

Speiser

²

,

McDougall

³

et al. 2020

Preprint

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Molluscs biomineralize structures that vary in composition, form, and function, prompting questions about the genetic mechanisms responsible for their production and the evolution of these mechanisms. Chitons (Mollusca, Polyplacophora) are a promising system for studies of biomineralization because they build a range of calcified structures including shell plates and spine- or scale-like sclerites. Chitons also harden the teeth of their rasp-like radula with a coat of iron. Here we present the genome of the West Indian fuzzy chiton Acanthopleura granulata, the first from any aculiferan mollusc. The A. granulata genome has features that may be specialized for iron biomineralization, including a high proportion of genes regulated directly by iron and two isoforms of ferritin, one iron-regulated and the other constitutively translated. The A. granulata genome also contains homologs of many biomineralization genes identified previously in conchiferan molluscs, suggesting the ancestral mollusc had a diverse genetic toolkit for biomineralization.

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“…Some species of chitons can be eaten as food and have great medicinal interest [19][20][21][22][23]. The radular teeth of chitons, containing large amounts of magnetite in the form of nanoparticles, were found to be interesting research materials of biomineralization, magnetic materials and natural nanomaterials [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Genetic Diversity and Population Structure of Acanthochiton rubrolineatus (Polyplacophora) Based on Mitochondrial and Nuclear Gene Markers

Xu

¹

,

Chu

²

,

Zhang

³

et al. 2020

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Acanthochiton rubrolineatus (Cryptoplacidae, Neoloricata, Polyplacophora) has a narrow distribution range along the seacoasts of China, the Korean Peninsula and Japan. We collected 238 samples from eight localities along the Chinese coast, and analyzed the genetic diversity and population structure with COI, 16S-rRNA and 28S-rRNA gene sequences. All analyses based on combined sequences of COI and 16S-rRNA suggested that there was evident genetic differentiation between the northern populations (YT, WH, DL, QD, LYG) and southern populations (ZS, YH, XM) of A. rubrolineatus. The haplotype distribution pattern and genetic diversity based on 28S-rRNA sequences also supported the genetic divergence between the two groups. Both groups had experienced population expansion after the ice age of Pleistocene, and an additional population bottleneck had happened in the southern group in recent history, which led to low genetic diversity of mitochondrial DNA and abnormally high diversity of nuclear DNA in this group. Our results suggested that the protection on A. rubrolineatus is necessary, and the northern and southern group should be protected separately.

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The Chiton Radula: A Model System for Versatile Use of Iron Oxides*

Cited by 26 publications

References 116 publications

The Iron-Responsive Genome of the Chiton Acanthopleura granulata

The Iron-Responsive Genome of the Chiton Acanthopleura granulata

The iron-responsive genome of the chitonAcanthopleura granulata

Genetic Diversity and Population Structure of Acanthochiton rubrolineatus (Polyplacophora) Based on Mitochondrial and Nuclear Gene Markers

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