Project description:By applying Illumina Novaseq 6000, Chlorella sp. TLD6B cells of the control group on day zero and 18, as well as under low salt stress (NaCl1) and under high salt stress (NaCl2) on day 18 were selected for transcriptome sequencing analysis. Meanwhile, 0.05 g/mL ( PEG1) and 0.1 g/mL PEG-6000 (medium for drought stress, PEG2 ) were used to prepare the drought-stressed Chlorella sp. TLD6B cells. Each treatment had two replicates. Clean data were filtered after the removal of adapters, poly-N strands, and low-quality reads. There were no reference genomes for Chlorella sp. TLD6B, and de novo assembly for clean reads was performed by using Trinity. The sequences were compared with databases such as NR, NT, Swiss-Pro, GO, KEGG, PFAM, and KOG using Blast X (e-value ≤ 10-5). The GO annotation of unigenes was obtained using BLAST2GO. FPKM method was used for the analysis of gene expression levels (Trapnell et al., 2010). Out of six samples, a total of 963,078,184 raw reads were generated. A total of 947,225,244 clean reads were obtained based on the base quality score and read length. Meanwhile, the GC percentage in clean reads reached nearly 66.0%, with Q20 being above 96%. A total of 219,577 transcripts with an average length of 1,394 bp were obtained. In total, 155,503 non-redundant unigenes were assembled for the following analyses. The length of the unigenes ranged from 200 bp to 23,825 bp, with an average length of 1,842 bp. Under different salt stress, verification had been conducted with qRT-PCR on nine unigenes of different pathways, which were related to lipid metabolism. The detection results by qRT-PCR were highly correlated with RNA-Seq results (r = 0.890, r2 = 0.791), which indicated that the RNA-Seq data of Chlorella sp. TLD6B under salt stress were accurate and reliable. Our study represents the first detailed analysis of Chlorella sp. TLD6B under salt stress transcriptomes. Hierarchical clustering of differentially expressed genes uncovered several currently uncharacterized genes that may contribute to the function about lipid accumulation of Chlorella sp. TLD6B under salt stress.

Project description:Chlorella has been reported to have various physiological activities, including antiarteriosclerotic, cholesterol-lowering, anti-inflammatory, and immunoregulatory effects. However, there has been no report on the long-term effects of chlorella ingestion on immunity. In the present study, 4- to 10-week-old (young) and 4- to 50-week-old (old) female BALB/c mice were sensitized or not with ovalbumin (OVA), and given basic diet containing chlorella powder at 2% or basic diet alone. The effects of chlorella ingestion on immunity were investigated by measurement of splenic cytokines and immunoglobulin (Ig), analysis of T- and B-cells in the spleen and small intestine by flow cytometry, and analysis of the liver by DNA microarray. Results were compared between the young and old, OVA-sensitized and -nonsensitized, and chlorella and non-chlorella ingestion groups. Production of interferon-γ (IFN-γ) was maintained in the nonsensitized old groups, and ratios of T-helper type 1 (Th1) to T-helper type 2 (Th2) cells were similar in the young and old groups. In addition, overproduction of OVA-specific Igs due to OVA sensitization was strongly suppressed, and significant immunotolerance was exhibited irrespective of age. In addition, suppression of T-cell decreases in the spleen due to aging and suppression of changes in T- and B-cells due to OVA sensitization in the small intestinal lymph were demonstrated on flow cytometric analyses. On DNA microarray analysis, immune-related terms including IL11 and major histocompatibility complex (MHC) class 1 were detected, and expression of genes was shown, which were related to IL1-linked genes and complex involving macrophages from the pathways of cytokines and inflammatory response. In addition, suppressions of declined lipid metabolism and energy production were also suggested. Although how the ingredients in chlorella were involved in these changes is unclear, our findings suggest that prevention of decrease in acquired immunity by aging and induction of strong immunotolerance occurred following chlorella ingestion. The Young Control group and Old Control group were fed normal food, and the Old Chlorella intake group was fed food including 2.0% Chlorella powder. The total RNA was isolated from liver and samples was pooled for each group (n = 6 for each group). A table of normalized log2 ratios (where numerator is sample expression data, and denominator is all sample median data) is linked below as a supplementary file.

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Chlorella sp. ArM0029B

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