Dataset Information

RNA-Seq and microarray analysis of the Xenopus inner ear transcriptome discloses orthologous OMIM(®) genes for hereditary disorders of hearing and balance.

ABSTRACT: Auditory and vestibular disorders are prevalent sensory disabilities caused by genetic and environmental (noise, trauma, chemicals) factors that often damage mechanosensory hair cells of the inner ear. Development of treatments for inner ear disorders of hearing and balance relies on the use of animal models such as fish, amphibians, reptiles, birds, and non-human mammals. Here, we aimed to augment the utility of the genus Xenopus for uncovering genetic mechanisms essential for the maintenance of inner ear structure and function.Using Affymetrix GeneChip(®) X. laevis Genome 2.0 Arrays and Illumina-Solexa sequencing methods, we determined that the transcriptional profile of the Xenopus laevis inner ear comprises hundreds of genes that are orthologous to OMIM(®) genes implicated in deafness and vestibular disorders in humans. Analysis of genes that mapped to both technologies demonstrated that, with our methods, a combination of microarray and RNA-Seq detected expression of more genes than either platform alone.As part of this study we identified candidate scaffold regions of the Xenopus tropicalis genome that can be used to investigate hearing and balance using genetic and informatics procedures that are available through the National Xenopus Resource (NXR), and the open access data repository, Xenbase. The results and approaches presented here expand the viability of Xenopus as an animal model for inner ear research.

SUBMITTER: Ramirez-Gordillo D

PROVIDER: S-EPMC4652436 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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RNA-Seq and microarray analysis of the Xenopus inner ear transcriptome discloses orthologous OMIM(®) genes for hereditary disorders of hearing and balance.

Ramírez-Gordillo Daniel D Powers TuShun R TR van Velkinburgh Jennifer C JC Trujillo-Provencio Casilda C Schilkey Faye F Serrano Elba E EE

BMC research notes 20151118

<h4>Background</h4>Auditory and vestibular disorders are prevalent sensory disabilities caused by genetic and environmental (noise, trauma, chemicals) factors that often damage mechanosensory hair cells of the inner ear. Development of treatments for inner ear disorders of hearing and balance relies on the use of animal models such as fish, amphibians, reptiles, birds, and non-human mammals. Here, we aimed to augment the utility of the genus Xenopus for uncovering genetic mechanisms essential fo ...[more]

PMID: 26582541

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Project description:Purpose: To identify orthologous genes in Xenopus that are implicated in deafness and vestibular disorders in humans and to compare RNA-Seq and microarray to determine the advantages of each technology for Xenopus transcriptomic analysis. Methods: Inner ear RNA from X. laevis stages 56-58 was isolated with the Qiagen® RNeasy® Mini Kit. RNA quality was assessed using the Agilent 2100 Bioanalyzer. The RNA was sent to the National Center for Genome Resources, for Illumina-Solexa sequencing using the genome analyzer II and to MIT for microarray processing usign the Affymetrix GeneChip® X. laevis Genome 2.0 Array. The OMIM database was mined for identification of genes causing deafness and vestibular disorder in humans. Human sequences for each of the deafness and vestibular disorders genes were downloaded from Ensembl. Blast-2.2.27+ was used to mapped the human sequences against X. tropicalis predicted proteins from JGI or to Xenopus consensus sequences downloaded from Affymetrix. The alignment of the human sequences to the predicted proteins resulted in the identification of the protein designation number. The protein designation number was used to obtain the sacaffold number and coordinates from JGI genome browser. The scaffold number and coordinates were input into Alpheus sequence variant detection pipeline to obtain the number of reads associated with each gene. The reads were log2 transformed for comparison to the microarray. In the case of the alignment of the human sequences to the Xenopus consensus sequences resulted in the PSID. The PSID was used to obtain the GCRMA intensity value. The GCRMA value and the number of reads were compared to determine which technology detected more genes. Results: Using Affymetrix GeneChip® X. laevis Genome 2.0 Arrays and Illumina-Solexa sequencing methods, we determined that the transcriptional profile of the Xenopus inner ear comprises hundreds of genes that are orthologous to OMIM® genes implicated in deafness and vestibular disorders in humans. Analysis of genes that mapped to both technologies showed that RNA-Seq detected more of both deafness and vestibular disorder than the Microarray. RNA-Seq and microarray detected 108 genes but RNA-Seq detected 48 genes that were below threshold criteria for microarray. While the microarray detected 11 genes that were below the expression criteria for RNA-Seq and 23 genes were below the threshold criteria for both technologies. Further analysis of the 108 genes detected by both technologies showed a minor correlation between the two technologies. Conclusions: As part of this study we identified candidate scaffold regions of the Xenopus tropicalis genome that can be used for gene mutagenesis. Furthermore, results from this study showed that the two technologies can complement each other and that a combination of both approaches can provide a more complete analysis of gene expression than either method alone.

Project description:Purpose: To identify orthologous genes in Xenopus that are implicated in deafness and vestibular disorders in humans and to compare RNA-Seq and microarray to determine the advantages of each technology for Xenopus transcriptomic analysis. Methods: Inner ear RNA from X. laevis stages 56-58 was isolated with the QiagenÂ® RNeasyÂ® Mini Kit. RNA quality was assessed using the Agilent 2100 Bioanalyzer. The RNA was sent to the National Center for Genome Resources, for Illumina-Solexa sequencing using the genome analyzer II and to MIT for microarray processing usign the Affymetrix GeneChipÂ® X. laevis Genome 2.0 Array. The OMIM database was mined for identification of genes causing deafness and vestibular disorder in humans. Human sequences for each of the deafness and vestibular disorders genes were downloaded from Ensembl. Blast-2.2.27+ was used to mapped the human sequences against X. tropicalis predicted proteins from JGI or to Xenopus consensus sequences downloaded from Affymetrix. The alignment of the human sequences to the predicted proteins resulted in the identification of the protein designation number. The protein designation number was used to obtain the sacaffold number and coordinates from JGI genome browser. The scaffold number and coordinates were input into Alpheus sequence variant detection pipeline to obtain the number of reads associated with each gene. The reads were log2 transformed for comparison to the microarray. In the case of the alignment of the human sequences to the Xenopus consensus sequences resulted in the PSID. The PSID was used to obtain the GCRMA intensity value. The GCRMA value and the number of reads were compared to determine which technology detected more genes. Results: Using Affymetrix GeneChipÂ® X. laevis Genome 2.0 Arrays and Illumina-Solexa sequencing methods, we determined that the transcriptional profile of the Xenopus inner ear comprises hundreds of genes that are orthologous to OMIMÂ® genes implicated in deafness and vestibular disorders in humans. Analysis of genes that mapped to both technologies showed that RNA-Seq detected more of both deafness and vestibular disorder than the Microarray. RNA-Seq and microarray detected 108 genes but RNA-Seq detected 48 genes that were below threshold criteria for microarray. While the microarray detected 11 genes that were below the expression criteria for RNA-Seq and 23 genes were below the threshold criteria for both technologies. Further analysis of the 108 genes detected by both technologies showed a minor correlation between the two technologies. Conclusions: As part of this study we identified candidate scaffold regions of the Xenopus tropicalis genome that can be used for gene mutagenesis. Furthermore, results from this study showed that the two technologies can complement each other and that a combination of both approaches can provide a more complete analysis of gene expression than either method alone. Inner ear RNA from X. laevis larval stages 56-58 was isolated and shipped to the National Center for Genome Resources, for Illumina-Solexa sequencing or to the Massachusetts Institute of Technology BioMicro Center for microarray analysis with the Affymetrix GeneChipÂ® X. laevis Genome 2.0 Array. RNA-Sequencing was completed using the Illumina-Solexa platform for sequencing by synthesis. Short-insert paired end (SIPE) libraries were prepared from total RNA according to Illuminaâ??s mRNA-Seq Sample Prep Protocol v2.0 (Illumina, San Diego, CA, USA). The resultant double-stranded cDNA concentration was measured on a NanoDrop spectrophotometer, and size and purity were determined on the 2100 Bioanalyzer using a DNA 1000 Nano kit. The cDNA libraries were cluster amplified on Illumina flowcells, sequenced on the GAII Sequencer as 36-cycle single-end reads, and processed using Illumina software v1.0. Illumina reads were aligned to the X. tropicalis genome using the algorithm for genomic mapping and alignment program (GMAP) and AlpheusÂ® Sequence Variant Detection System v3.1.

Project description:BackgroundThe senses of hearing and balance depend upon mechanoreception, a process that originates in the inner ear and shares features across species. Amphibians have been widely used for physiological studies of mechanotransduction by sensory hair cells. In contrast, much less is known of the genetic basis of auditory and vestibular function in this class of animals. Among amphibians, the genus Xenopus is a well-characterized genetic and developmental model that offers unique opportunities for inner ear research because of the amphibian capacity for tissue and organ regeneration. For these reasons, we implemented a functional genomics approach as a means to undertake a large-scale analysis of the Xenopus laevis inner ear transcriptome through microarray analysis.ResultsMicroarray analysis uncovered genes within the X. laevis inner ear transcriptome associated with inner ear function and impairment in other organisms, thereby supporting the inclusion of Xenopus in cross-species genetic studies of the inner ear. The use of gene categories (inner ear tissue; deafness; ion channels; ion transporters; transcription factors) facilitated the assignment of functional significance to probe set identifiers. We enhanced the biological relevance of our microarray data by using a variety of curation approaches to increase the annotation of the Affymetrix GeneChip(®) Xenopus laevis Genome array. In addition, annotation analysis revealed the prevalence of inner ear transcripts represented by probe set identifiers that lack functional characterization.ConclusionsWe identified an abundance of targets for genetic analysis of auditory and vestibular function. The orthologues to human genes with known inner ear function and the highly expressed transcripts that lack annotation are particularly interesting candidates for future analyses. We used informatics approaches to impart biologically relevant information to the Xenopus inner ear transcriptome, thereby addressing the impediment imposed by insufficient gene annotation. These findings heighten the relevance of Xenopus as a model organism for genetic investigations of inner ear organogenesis, morphogenesis, and regeneration.

Dataset Information

RNA-Seq and microarray analysis of the Xenopus inner ear transcriptome discloses orthologous OMIM(®) genes for hereditary disorders of hearing and balance.

Publications

RNA-Seq and microarray analysis of the Xenopus inner ear transcriptome discloses orthologous OMIM(®) genes for hereditary disorders of hearing and balance.

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