Project description:In flies, repeat-associated small interfering RNAs (rasiRNAs) ensure genomic stability by silencing endogenous selfish genetic elements such as retrotransposons and repetitive sequences. Here, we show that while small interfering RNAs (siRNAs) derive from both the sense and antisense strands of their double-stranded RNA precursors, rasiRNAs arise mainly from the antisense strand. rasiRNA production appear not to require Dicer-1, which makes microRNAs, or Dicer-2, which makes siRNAs, and rasiRNAs lack the 2´,3´ hydroxy termini characteristic of animal siRNA and miRNA. Unlike siRNAs and miRNAs, rasiRNAs function through the Piwi, rather than the Ago, Argonaute protein subfamily. Thus, rasiRNAs define a third RNA silencing pathway distinct from both the miRNA and RNAi pathways. Keywords: gene silencing; post-transcriptional gene regulation; short RNAs; RNAi; rasiRNAs; rasiRNA; microRNAs; microRNA; siRNAs; siRNA
Project description:As part of the ENCODE consortium the GENCODE project is producing a reference gene set through manual and automated gene prediction. In the current phase of ENCODE we have found strong evidence that many lncRNAs transcript termini are still unknown. This experiment aims to set up an experimental validation strategy to accurately determine the 5' and 3' ends of transcripts, which is based on semi-nested RACE extensions of annotated 5' and 3' ends followed by high throughput sequencing. A total of 400 highly expressed lncRNA transcript models from Gencode 7 which did not have any CAGE/PET support were selected as the test set whereas 25 transcripts with transcript start site (TSS) supported by CAGE tags and transcript termination site (TTS) supported by PET ditags formed the positive control set. Transcript ends were amplified by RACE-PCR from brain and testis RNA samples and sequenced using the Roche 454 platform. The sequencing was performed at the Andalusian Human Genome Sequencing Centre (CASEGH), Seville, Spain.
Project description:As part of the ENCODE consortium the GENCODE project is producing a reference gene set through manual and automated gene prediction. In the current phase of ENCODE we have found strong evidence that many lncRNAs transcript termini are still unknown. This experiment aims to set up an experimental validation strategy to accurately determine the 5' and 3' ends of transcripts, which is based on semi-nested RACE extensions of annotated 5' and 3' ends followed by high throughput sequencing. A total of 400 highly expressed lncRNA transcript models from Gencode 7 which did not have any CAGE/PET support were selected as the test set whereas 25 transcripts with transcript start site (TSS) supported by CAGE tags and transcript termination site (TTS) supported by PET ditags formed the positive control set. Transcript ends were amplified by RACE-PCR from brain and testis RNA samples and sequenced using the Roche 454 platform. The sequencing was performed at the Centre for Genomic Regulation (CRG), Barcelona, Spain.
Project description:MicroRNAs (miRNAs) are short (∼ 21-23 nt) regulatory RNAs that guide the degradation or translational repression of their RNA targets. The miRNA “seed”—nucleotides 2 through 7—establishes miRNA target specificity, because this region is the primary determinant of RNA binding by both miRNA and small interfering RNAs. Accurate processing of the miRNA 5´ end is thought to be under strong selective pressure, as a shift by just one nucleotide in the 5´ end of a miRNA would alter its seed sequence, redefining its repertoire of targets. Animal miRNAs are produced by the sequential cleavage of partially double-stranded precursor RNAs by the RNase III endonucleases Drosha, which cleaves the primary miRNA transcript in the nucleus to release a pre-miRNA, and Dicer, which cleaves the pre-miRNA to generate a transitory intermediate comprising the mature miRNA paired with its miRNA* strand. Here, we report that in flies, the 5´ end of a miRNA is typically more precisely defined than the 3´ ends of both the miRNA and its miRNA*. Surprisingly, the 5´ end of the miRNA* sequence was also more precisely defined than the adjacent 3´ end of the miRNA. Our data imply either that many miRNA* sequences are under evolutionary pressure to maintain their seed sequences—that is, they have cellular or exogenous RNA targets—or that secondary constraints, such as the sequence requirements for loading small RNAs into functional Argonaute protein complexes narrow the range of miRNA and miRNA* 5´ ends that accumulate in flies. Keywords: microRNA deep sequencing; pyrosequencing
Project description:Age-matched stage 13 embryos were dissected and cDNA of 8 organs from each embryo were sequenced. The organs were foregut, anterior midgut, posterior midgut, hindgut, Malpighian tubules, left salivary gland, right salivary gland, ventral nerve cord. Gene expression, transcription start and stop sites, and strands of termini were analysed. SMART amplification adapters were used for finding transcript termini and for phasing.
Project description:A method for the long-term maintenance of germ-free flies was established using aseptic isolators. The methodology effectively and reliably yields large numbers of germ-free flies in homogeneous cultures. Germ-free flies exhibited increased lifespan (only female flies) and decreased egg production, markedly reduced fat storage, less midday sleep, and enhanced aggressiveness (male flies). Fructilactobacillus—a species of fly intestinal microbes—was re-colonized in germ-free flies, and these gnotobiotic flies were successfully maintained for numerous generations. The proteome of those flies were analyzed.
Project description:As part of the ENCODE consortium the GENCODE project is producing a reference gene set through manual and automated gene prediction. In the current phase of ENCODE we have found strong evidence that many lncRNAs transcript termini are still unknown. This experiment aims to set up an experimental validation strategy to accurately determine the 5' and 3' ends of transcripts, which is based on semi-nested RACE extensions of annotated 5' and 3' ends followed by high throughput sequencing. A total of 400 highly expressed lncRNA transcript models from Gencode 7 which did not have any CAGE/PET support were selected as the test set whereas 25 transcripts with transcript start site (TSS) supported by CAGE tags and transcript termination site (TTS) supported by PET ditags formed the positive control set. Transcript ends were amplified by RACE-PCR from RNA samples from five different tissues (heart, kidney, liver, lung and spleen) and sequenced using the Roche 454 platform. The sequencing was performed at the Andalusian Human Genome Sequencing Centre (CASEGH), Seville, Spain.
Project description:We have developed both WTSS-seq (whole transcriptome start site sequencing) and WTTS-seq (whole transcriptome termini site sequencing) methods to capture either 5’- or 3’-ends of transcripts. HATT-seq (head and tail tag sequencing) is still under development, which can be used to capture both 5’- and 3’ ends of each transcript simultaneously. Iso-seq was used to produce full-length transcripts, which can be used to validate both alternative transcription start sites and alternative polyadenylation sites. CAGE-seq was used to confirm alternative transcription start sites only.
Project description:Protein termini play pivotal roles in various biological processes. Although a series of terminomic strategies have been proposed for the analysis of protein N-termini or protein C-termini separately, few can analyze both ends of proteins at the same time. Herein, we developed a workflow, termed Simultaneous Analysis of Protein N- and C- Terminome (SAPT) based on strong cation exchange chromatography (SCX) to study protein terminome simultaneously.