Project description:The cockroach Blattella germanica obtains nitrogen from uric acid through a metabolic pathway shared with its bacterial endosymbiont
Project description:Uric acid stored in the fat body of cockroaches is a nitrogen reservoir mobilized in times of scarcity. The discovery of urease in Blattabacterium cuenoti, the primary endosymbiont of cockroaches, suggests that the endosymbiont may participate in cockroach nitrogen economy. However, bacterial urease may only be one piece in the entire nitrogen recycling process from insect uric acid. Thus, in addition to the uricolytic pathway to urea, there must be glutamine synthetase assimilating the released ammonia by the urease reaction to enable the stored nitrogen to be metabolically usable.
Project description:microRNAs (miRNAs) have been reported as key regulators in the post-transcriptional process in eukaryotic cells. In insects most of the studies have been reported in holometabolans while only recently two hemimetabolansM-BM- (Locusta migratoria and Acyrthosiphonpisum) have had their miRNAs identified. Therefore, the study on miRNAs of the evolutionarily basal hemimetabolanM-BM- Blattella germanica, may provide valuable insights on the structural and functional evolution of miRNAs. Small RNA libraries of the cockroach B. germanica were built from the whole body of the last instar nymph, and the adult ovaries. The high throughput Solexa sequencing resulted in approximately 11 and 8 million reads for the whole-body andM-BM- ovaries, respectively. Bioinformatic analyses identified 38 known miRNAs as well as 11 known miRNA*s. We also found 411 miRNA candidates conserved in other insects and 1017 candidates specific of B. germanica. The positive correlation between Solexa data and real-time quantitative PCR showed that reads can be used as quantitative method. Novel miRNA candidates were validated by decreasing levels of expression in dicer-1 RNAi knockdown individuals. The comparison of the two libraries indicates that whole-body nymph contain more known miRNAs than ovaries, whereas the adult ovaries are enriched with novel miRNA candidates. Our study has identified many known miRNAs and novel miRNA candidates in the basal hemimetabolan insect B. germanica, and most of the specific sequences were found in ovaries. Deep sequencing data reflect miRNA abundance and Dicer-1 RNAi assay is a reliable method to validate novel miRNAs. Small RNAs were sequenced whole body of the last instar nymph and adult ovaries of the cockroach Blattella germanica.
Project description:Uric acid stored in the fat body of cockroaches is a nitrogen reservoir mobilized in times of scarcity. The discovery of urease in Blattabacterium cuenoti, the primary endosymbiont of cockroaches, suggests that the endosymbiont may participate in cockroach nitrogen economy. However, bacterial urease may only be one piece in the entire nitrogen recycling process from insect uric acid. Thus, in addition to the uricolytic pathway to urea, there must be glutamine synthetase assimilating the released ammonia by the urease reaction to enable the stored nitrogen to be metabolically usable. None of the Blattabacterium genomes sequenced to date possess genes encoding for those enzymes. To test the host's contribution to the process, we have sequenced and analysed Blattella germanica transcriptomes from the fat body. We identified transcripts corresponding to all genes necessary for the synthesis of uric acid and its catabolism to urea, as well as for the synthesis of glutamine, asparagine, proline and glycine, i.e. the amino acids required by the endosymbiont. We also explored the changes in gene expression with different dietary protein levels. It appears that the ability to use uric acid as a nitrogen reservoir emerged in cockroaches after its age-old symbiotic association with bacteri
