De Novo Transcriptome of the Hemimetabolous German Cockroach (\u3ci\u3eBlattella germanica\u3c/i\u3e)

Background: The German cockroach, Blattella germanica, is an important insect pest that transmits various pathogens mechanically and causes severe allergic diseases. This insect has long served as a model system for studies of insect biology, physiology and ecology. However, the lack of genome or transcriptome information heavily hinder our further understanding about the German cockroach in every aspect at a molecular level and on a genome-wide scale. To explore the transcriptome and identify unique sequences of interest, we subjected the B. germanica transcriptome to massively parallel pyrosequencing and generated the first reference transcriptome for B. germanica. Methodology/Principal Findings: A total of 1,365,609 raw reads with an average length of 529 bp were generated via pyrosequencing the mixed cDNA library from different life stages of German cockroach including maturing oothecae, nymphs, adult females and males. The raw reads were de novo assembled to 48,800 contigs and 3,961 singletons with highquality unique sequences. These sequences were annotated and classified functionally in terms of BLAST, GO and KEGG, and the genes putatively coding detoxification enzyme systems, insecticide targets, key components in systematic RNA interference, immunity and chemoreception pathways were identified. A total of 3,601 SSRs (Simple Sequence Repeats) loci were also predicted. Conclusions/Significance: The whole transcriptome pyrosequencing data from this study provides a usable genetic resource for future identification of potential functional genes involved in various biological processes

De Novo Transcriptome of the Hemimetabolous German Cockroach (\u3ci\u3eBlattella germanica\u3c/i\u3e)

Background: The German cockroach, Blattella germanica, is an important insect pest that transmits various pathogens mechanically and causes severe allergic diseases. This insect has long served as a model system for studies of insect biology, physiology and ecology. However, the lack of genome or transcriptome information heavily hinder our further understanding about the German cockroach in every aspect at a molecular level and on a genome-wide scale. To explore the transcriptome and identify unique sequences of interest, we subjected the B. germanica transcriptome to massively parallel pyrosequencing and generated the first reference transcriptome for B. germanica. Methodology/Principal Findings: A total of 1,365,609 raw reads with an average length of 529 bp were generated via pyrosequencing the mixed cDNA library from different life stages of German cockroach including maturing oothecae, nymphs, adult females and males. The raw reads were de novo assembled to 48,800 contigs and 3,961 singletons with highquality unique sequences. These sequences were annotated and classified functionally in terms of BLAST, GO and KEGG, and the genes putatively coding detoxification enzyme systems, insecticide targets, key components in systematic RNA interference, immunity and chemoreception pathways were identified. A total of 3,601 SSRs (Simple Sequence Repeats) loci were also predicted. Conclusions/Significance: The whole transcriptome pyrosequencing data from this study provides a usable genetic resource for future identification of potential functional genes involved in various biological processes

<i>De Novo</i> Transcriptome of the Hemimetabolous German Cockroach (<i>Blattella germanica</i>)

<div><p>Background</p><p>The German cockroach, <i>Blattella germanica</i>, is an important insect pest that transmits various pathogens mechanically and causes severe allergic diseases. This insect has long served as a model system for studies of insect biology, physiology and ecology. However, the lack of genome or transcriptome information heavily hinder our further understanding about the German cockroach in every aspect at a molecular level and on a genome-wide scale. To explore the transcriptome and identify unique sequences of interest, we subjected the <i>B. germanica</i> transcriptome to massively parallel pyrosequencing and generated the first reference transcriptome for <i>B. germanica</i>.</p><p>Methodology/Principal Findings</p><p>A total of 1,365,609 raw reads with an average length of 529 bp were generated via pyrosequencing the mixed cDNA library from different life stages of German cockroach including maturing oothecae, nymphs, adult females and males. The raw reads were <i>de novo</i> assembled to 48,800 contigs and 3,961 singletons with high-quality unique sequences. These sequences were annotated and classified functionally in terms of BLAST, GO and KEGG, and the genes putatively coding detoxification enzyme systems, insecticide targets, key components in systematic RNA interference, immunity and chemoreception pathways were identified. A total of 3,601 SSRs (Simple Sequence Repeats) loci were also predicted.</p><p>Conclusions/Significance</p><p>The whole transcriptome pyrosequencing data from this study provides a usable genetic resource for future identification of potential functional genes involved in various biological processes.</p></div

Summary statistics of the ESTs generated from the German cockroach through pyrosequencing.

<p>Summary statistics of the ESTs generated from the German cockroach through pyrosequencing.</p

Phylogeny of the OBPs (A) and CSPs (B) from the German cockroach and their homologs.

<p>The unrooted consensus trees with 1000 bootstrap replicates are generated in MEGA6 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0106932#pone.0106932-Tamura1" target="_blank">[39]</a> using the neighbor-joining method. The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. All positions containing gaps and missing data are eliminated. GenBank accession numbers and species names of the sequences used here are shown in the phylogenetic trees. German cockroach OBPs and CSPs (marked by •) are in bolds.</p

Length distribution of clean reads (A) produced by 454 pyrosequencing and the assembled unigenes (B).

<p>Length distribution of clean reads (A) produced by 454 pyrosequencing and the assembled unigenes (B).</p

Eukaryotic orthologous groups (KOG) function classification of 52,761 unigenes of <i>Blattella germanica</i>.

<p>Eukaryotic orthologous groups (KOG) function classification of 52,761 unigenes of <i>Blattella germanica</i>.</p

Summary of top 20 abundant assembled unigenes from the German cockroach transcriptome.

<p>Summary of top 20 abundant assembled unigenes from the German cockroach transcriptome.</p

Genes related to important physiological functions.

<p>Genes related to important physiological functions.</p