Dataset Information

Molecular influences relating to the development and biomineralization of the chiton radula, Acanthopleura histosa

ABSTRACT: Chitons are marine molluscs that posses a radula, a tongue like appendage containing many rows of microscopic teeth used for feeding. These teeth are hardened through the incorporation of biominerals. Since the original discovery of iron oxide and magnetite in these teeth, a wealth of chemical and structural knowledge has accumulated. The biomineralization process is known to be matrix mediated with precise control of the deposition of a number of different iron and calcium minerals at readily identifiable stages of tooth development. While much is known about the mechanisms of tooth mineralisation, there have been no studies undertaken to identify the genes that regulate this process. This investigation uses microarray technology to analyse the spatial expression of 493 expressed sequence tags (EST) derived from the radula sac of chiton, Acanthopleura hirtosa. A number of ESTs have been deemed significantly differentially expressed in relation to three designated areas of the radula sac. These spatial sections are defined by the variation in biomineral deposits of the radula, being immature radula which lacks any biomineral incorporation, iron deposition and calcium deposition. Additionally, foot muscle was used as a control to specify whether EST expression was specific to the radula and therefore likely involved biomineralization.

ORGANISM(S): Acanthopleura hirtosa

PROVIDER: GSE20105 | GEO | 2010/06/25

SECONDARY ACCESSION(S): PRJNA124235

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:Chitons are marine molluscs that posses a radula, a tongue like appendage containing many rows of microscopic teeth used for feeding. These teeth are hardened through the incorporation of biominerals. Since the original discovery of iron oxide and magnetite in these teeth, a wealth of chemical and structural knowledge has accumulated. The biomineralization process is known to be matrix mediated with precise control of the deposition of a number of different iron and calcium minerals at readily identifiable stages of tooth development. While much is known about the mechanisms of tooth mineralisation, there have been no studies undertaken to identify the genes that regulate this process. This investigation uses microarray technology to analyse the spatial expression of 493 expressed sequence tags (EST) derived from the radula sac of chiton, Acanthopleura hirtosa. A number of ESTs have been deemed significantly differentially expressed in relation to three designated areas of the radula sac. These spatial sections are defined by the variation in biomineral deposits of the radula, being immature radula which lacks any biomineral incorporation, iron deposition and calcium deposition. Additionally, foot muscle was used as a control to specify whether EST expression was specific to the radula and therefore likely involved biomineralization. A total of twelve A. hirtosa specimens were collected and sacrificed for microarray hybridizations. The radulae were removed from each animal immediately following sacrifice and dissected into three sections based on the biomineralisation development of the radula teeth. These sections are termed immature teeth, iron deposited teeth, and calcium deposited teeth. An additional sample of A. hirtosa foot muscle was taken from each specimen. RNA was extracted individually from these sections. Extracted RNA samples across subjects were pooled equally within sections in order to minimize the impact of biological variation and maximize the number of individual samples included in the study. To this effect, four single channel hybridizations were conducted for each radula and muscle section each representing a pooled biological replicate containing equal proportions of RNA from three A. hirtosa individuals. A total of sixteen microarray hybridizations were conducted in this manner.

Project description:One of the most complex prokaryotic organelles are magnetosomes, which are formed by magnetotactic bacteria as sensors for navigation in the Earth’s magnetic field. In the alphaproteobacterium Magnetospirillum gryphiswaldense magnetosomes consist of chains of magnetite crystals (Fe3O4) that under suboxic conditions are biomineralized within membrane vesicles. To form such an intricate structure, the transcription of >30 specific structural genes clustered within the genomic magnetosome island (MAI) has to be coordinated with the expression of an as-yet unknown number of auxiliary genes encoding several generic metabolic functions. However, their global regulation and transcriptional organization in response to anoxic conditions most favorable for magnetite biomineralization are still unclear. Here, we compared transcriptional profiles of anaerobically grown magnetosome forming cells with those in which magnetosome biosynthesis has been suppressed by aerobic condition. Using whole transcriptome shotgun sequencing, we found that transcription of about 300 of the >4300 genes was significantly enhanced during magnetosome formation. The about 40 top upregulated genes are directly or indirectly linked to aerobic and anaerobic respiration (denitrification) or unknown functions. mam and mms gene clusters specifically controlling magnetosome biosynthesis were highly transcribed, but constitutively expressed irrespective of the growth condition. By Cappable-sequencing, we show that the transcriptional complexity of both the MAI and the entire genome decreased under anaerobic conditions optimal for magnetosome formation. In addition, predominant promoter structures were highly similar to sigma factor σ70 dependent promoters in other Alphaproteobacteria. Our transcriptome-wide analysis revealed that magnetite biomineralization relies on a complex interplay between generic metabolic processes such as aerobic and anaerobic respiration, cellular redox control, and the biosynthesis of specific magnetosome structures. In addition, we provide insights into global regulatory features that have remained uncharacterized in the widely studied model organism M. gryphiswaldense, including a comprehensive dataset of newly annotated transcription start sites and genome-wide operon detection as a community resource.

Dataset Information

Molecular influences relating to the development and biomineralization of the chiton radula, Acanthopleura histosa

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure