Project description:High-temperature stress (HTS) is one of the main environmental stresses that limit plant growth and crop production in agricultural systems. Maca (Lepidium meyenii) is an important high-altitude herbaceous plant adapted to a wide range of environmental stimuli such as cold, strong wind and UV-B exposure. However, it is an extremely HTS-sensitive plant species. Thus far, there is limited information about gene/protein regulation and signaling pathways related to the heat stress responses in maca. In this study, proteome profiles of maca seedlings exposed to HTS for 12 h were investigated using a tandem mass tag (TMT)-based proteomic approach. In total, 6,966 proteins were identified, of which 300 showed significant alterations in expression following HTS. Bioinformatics analyses indicated that protein processing in endoplasmic reticulum was the most significantly up-regulated metabolic pathway following HTS. Quantitative RT-PCR (qRT-PCR) analysis showed that the expression levels of 19 genes encoding proteins mapped to this pathway were significantly up-regulated under HTS. These results show that protein processing in the endoplasmic reticulum may play a crucial role in the responses of maca to HTS. Our proteomic data can be a good resource for functional proteomics of maca and our results may provide useful insights into the molecular response mechanisms underlying herbal plants to HTS.
Project description:High-throughput sequencing (HTS) has become a powerful tool for the detection of and sequence characterization of microRNAs (miRNA) and other small RNAs (sRNA). Unfortunately, the use of HTS data to determine the relative quantity of different miRNAs in a sample has been shown to be inconsistent with quantitative PCR and Northern Blot results. Several recent studies have concluded that the major contributor to this inconsistency is bias introduced during the construction of sRNA libraries for HTS and that the bias is primarily derived from the adaptor ligation steps; specifically where single stranded adaptors are sequentially ligated to the 3' and 5'-end of sRNAs using T4 RNA ligases. In this study we investigated the effects of ligation bias by using a pool of randomized ligation substrates, defined mixtures of miRNA sequences and several combinations of adaptors in HTS library construction. We show that like the 3' adaptor ligation step, the 5' adaptor ligation is also biased, not because of primary sequence, but instead due to secondary structures of the two ligation substrates. We find that multiple secondary structural factors influence final representation in HTS results. Our results provide insight about the nature of ligation bias and allowed us to design adaptors that reduce ligation bias and produce HTS results that more accurately reflect the actual concentrations of miRNAs in the defined starting material.
Project description:To further elucidate the role of miRNAs, HTS was used to screen differential miRNAs. Mice hippocampus from the saline group, the LPS group, and the LPS+GAS group were removed to analyze using HTS.
Project description:High-throughput sequencing (HTS) has become a powerful tool for the detection of and sequence characterization of microRNAs (miRNA) and other small RNAs (sRNA). Unfortunately, the use of HTS data to determine the relative quantity of different miRNAs in a sample has been shown to be inconsistent with quantitative PCR and Northern Blot results. Several recent studies have concluded that the major contributor to this inconsistency is bias introduced during the construction of sRNA libraries for HTS and that the bias is primarily derived from the adaptor ligation steps; specifically where single stranded adaptors are sequentially ligated to the 3' and 5'-end of sRNAs using T4 RNA ligases. In this study we investigated the effects of ligation bias by using a pool of randomized ligation substrates, defined mixtures of miRNA sequences and several combinations of adaptors in HTS library construction. We show that like the 3' adaptor ligation step, the 5' adaptor ligation is also biased, not because of primary sequence, but instead due to secondary structures of the two ligation substrates. We find that multiple secondary structural factors influence final representation in HTS results. Our results provide insight about the nature of ligation bias and allowed us to design adaptors that reduce ligation bias and produce HTS results that more accurately reflect the actual concentrations of miRNAs in the defined starting material. 28 samples were sequenced and the libraries were made using various synthetic oligo mixtures and adaptor combinations
Project description:High-throughput sequencing (HTS) of antibody amplicon libraries has become a powerful method in the emerging field of systems immunology. However, numerous sources of bias in HTS workflows may affect antibody repertoire data. A crucial step in antibody amplicon library preparation is the addition of adapter sequences, which are platform-specific short nucleotide sequences. In addition to conventional ligation-based adapter addition, it is also possible to use PCR-based methods such as Direct Addition (one-step adapter addition, DA) and Primer Extension (two-step adapter addition, PE), which have led to the lack of a consensus method and uncertainty regarding the impact of adapter addition on repertoire HTS data. Therefore, we compared all three methods by performing HTS with the Illumina MiSeq platform using total RNA originating from mouse antibody-secreting cells. We used technical replicate-based validation and clonal overlap and rank statistics to demonstrate that the two PCR-based methods produced HTS repertoires equivalent to ligation. Specifically: Nine BALB/c mice (8-10 weeks old, Charles River, specific-pathogen free) were immunized with 50 ug alum-precipitated chicken gamma globulin (CGG) conjugated to 4-hydroxy-3-nitrophenylacetyl (NP, NP-CGG, BioCat). Mice were sacrificed 14 days post-immunization (dpi) and their spleens and bone marrow (from femurs and tibia) were harvested. Antibody-secreting CD138-positive cells were enriched from spleen and bone marrow 14 dpi as previously described (Reddy, 2010, Nat Biotech).