Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (aw) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 aw exhibited decreased conidiation and aflatoxin biosynthesis compared to that under 0.99 aw. When RNA-Seq was used to delineate gene expression profile under different water activities, 23,320 non-redundant unigenes, with an average length of 1297 bp, were yielded. By database comparisons, 19,838 unigenes were matched well (e-value < 10−5) with known gene sequences, and another 6767 novel unigenes were obtained by comparison to the current genome annotation of A. flavus. Based on the RPKM equation, 5362 differentially expressed unigenes (with |log2Ratio| ≥ 1) were identified between 0.99 aw and 0.93 aw treatments, including 3156 up-regulated and 2206 down-regulated unigenes, suggesting that A. flavus underwent an extensive transcriptome response during water activity variation. Furthermore, we found that the expression of 16 aflatoxin producing-related genes decreased obviously when water activity decreased, and the expression of 11 development-related genes increased after 0.99 aw treatment. Our data corroborate a model where water activity affects aflatoxin biosynthesis through increasing the expression of aflatoxin producing-related genes and regulating development-related genes.
Background: Tumor purity plays a vital role in the biological process of solid tumors, but its function in gynecologic cancers remains unclear. This study explored the correlation between tumor purity and immune function of gynecological cancers and its reliability as a prognostic indicator of immunotherapy. Methods: Gynecological cancer-related datasets were downloaded from The Cancer Genome Atlas (TCGA). Tumor purity was calculated by the ESTIMATE algorithm. A LASSO Cox regression analysis was performed to construct the risk score model. A Kaplan–Meier Plotter was used to explore the relationships between tumor purity and cancer prognosis. We performed the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) to explore the pathways in the subgroups. A nomogram was used to quantitatively assess the cancer prognosis. Results: Tumor purity was negatively correlated with B cell infiltration in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC). Approximately 420 genes were positively associated with B cell infiltration and CESC prognosis and were enriched in immune-related signaling pathways. There were 11 key genes used to construct a risk score model. The low-risk group had a higher immune score and better prognosis than the high-risk group. A nomogram based on risk score, T stage, and clinical-stage had good predictive value in quantitatively evaluating CESC prognosis. Conclusions: This study is the first to reveal the correlation between tumor purity and immunity in CESC and suggests that low-risk patients may be more sensitive to immunotherapy. This provides a theoretical basis for the clinical treatment of CESC.
Tobacco (Nicotiana tabacum L.) is a leafy, annual, solanaceous plant grown commercially for its leaves in China. In continuing research on foliar diseases of tobacco in Guizhou province in August 2019, diseased leaves of tobacco that had sandy beige, elliptical or irregular shaped lesions, with brown in edge, and surrounded by yellow halos on 40% of leaves on 5% plants were obtained (cv. Yunyan 87) in Zhenan (28.55° N, 107.43° E), Guizhou, China (Fig. 1A, 1B). Diseased leaf segments were surface sterilized and plated on potato dextrose agar (PDA). Isolate (T41) was selected for identification. The colonies had white aerial hyphae, with orange-red on the underside when cultured on PDA (Fig. 1G, 1H). The colonies had woolly aerial hyphae, white to grey eventually, and produced pycnidia on oatmeal agar (OA) (Boerema et al. 2004) (Fig. 1I, 1J). Pycnidia were dark, spherical or flat spherical, and 69.2-178.0 µm in diameter. Conidia were oval mostly, aseptate, usually guttulate, and the size was 5.0 - 6.5 µm × 3.2 - 5.4 µm (Fig. 1K, 1L). The rDNA internal transcribed spacer region (ITS) with primers ITS1f/ITS4 (White et al. 1990; Gardes and Bruns 1993), 28S ribosomal RNA gene (LSU) with primers LROR/LR7 (Rehner and Samuels 1994), beta-tubulin gene (TUB2) with primers Btub2Fd/Btub4Rd (Woudenberg et al. 2009) and RNA polymerase II second largest subunit gene (RPB2) with primers RPB2-5F2/fRPB2-7cR (Liu et al. 1999) of T41 were sequenced (GenBank accession numbers were MN704804, MN710367, MN718012 and MN718013, respectively). Maximum Likelihood (ML) analyses and Bayesian Inferences (BI) analyses based on concatenated these four sequences were conducted with RAxML v. 7.2.6 and MrBayes v. 3.2.1, respectively, which showed that T41 comprised a clade with Epicoccum latusicollum strains (CGMCC 3.18346 and LC 8153) (ML/BI = 100/1) (Fig. 2). Based on morphological and multi-gene molecular data, isolate T41 was identified as E. latusicollum described as a new taxon by Chen et al. (2017). To verify pathogenicity, tobacco plants at seedling stage (7-8 leaves) without visible disease were inoculated using conidial suspension (106 spores/ml), following Guo et al. (2020). All inoculated plants were maintained in a greenhouse with relative humidity ranging from 50% to 85% at 28 °C under a 12/12 h light/dark cycle. Seven days after incubation, typical symptoms were observed on inoculated leaves but not on control leaves (Fig. 1C, 1D, 1E, 1F). Koch's postulates were fulfilled by re-isolation of E. latusicollum from diseased leaves. E. latusicollum has been reported to cause black root on yam in China (Han et al. 2019). Meanwhile, there are many plants could be caused leaf spot by this genus, such as Lablab purpureus (Mahadevakumar et al. 2014) and Bletilla striata (Zhou et al. 2018). However, to the best of our knowledge, this is the first report of E. latusicollum causing leaf spot on tobacco in China. Because considerable loss occurred due to infection from E. latusicollum on tobacco leaves, this pathogen is worthy of further study and disease management practices need to be developed to prevent further losses.
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