April 21, 2020  |  

Full-length transcriptome analysis of Litopenaeus vannamei reveals transcript variants involved in the innate immune system.

To better understand the immune system of shrimp, this study combined PacBio isoform sequencing (Iso-Seq) and Illumina paired-end short reads sequencing methods to discover full-length immune-related molecules of the Pacific white shrimp, Litopenaeus vannamei. A total of 72,648 nonredundant full-length transcripts (unigenes) were generated with an average length of 2545 bp from five main tissues, including the hepatopancreas, cardiac stomach, heart, muscle, and pyloric stomach. These unigenes exhibited a high annotation rate (62,164, 85.57%) when compared against NR, NT, Swiss-Prot, Pfam, GO, KEGG and COG databases. A total of 7544 putative long noncoding RNAs (lncRNAs) were detected and 1164 nonredundant full-length transcripts (449 UniTransModels) participated in the alternative splicing (AS) events. Importantly, a total of 5279 nonredundant full-length unigenes were successfully identified, which were involved in the innate immune system, including 9 immune-related processes, 19 immune-related pathways and 10 other immune-related systems. We also found wide transcript variants, which increased the number and function complexity of immune molecules; for example, toll-like receptors (TLRs) and interferon regulatory factors (IRFs). The 480 differentially expressed genes (DEGs) were significantly higher or tissue-specific expression patterns in the hepatopancreas compared with that in other four tested tissues (FDR <0.05). Furthermore, the expression levels of six selected immune-related DEGs and putative IRFs were validated using real-time PCR technology, substantiating the reliability of the PacBio Iso-seq results. In conclusion, our results provide new genetic resources of long-read full-length transcripts data and information for identifying immune-related genes, which are an invaluable transcriptomic resource as genomic reference, especially for further exploration of the innate immune and defense mechanisms of shrimp. Copyright © 2019 Elsevier Ltd. All rights reserved.

April 21, 2020  |  

Full-Length Transcriptome Analysis of the Genes Involved in Tocopherol Biosynthesis in Torreya grandis.

The seeds of Torreya grandis (Cephalotaxaceae) are rich in tocopherols, which are essential components of the human diet as a result of their function in scavenging reactive oxygen and free radicals. Different T. grandis cultivars (10 cultivars selected in this study were researched, and their information is shown in Table S1 of the Supporting Information) vary enormously in their tocopherol contents (0.28-11.98 mg/100 g). However, little is known about the molecular basis and regulatory mechanisms of tocopherol biosynthesis in T. grandis kernels. Here, we applied single-molecule real-time (SMRT) sequencing to T. grandis (X08 cultivar) for the first time and obtained a total of 97?211 full-length transcripts. We proposed the biosynthetic pathway of tocopherol and identified eight full-length transcripts encoding enzymes potentially involved in tocopherol biosynthesis in T. grandis. The results of the correlation analysis between the tocopherol content and gene expression level in the 10 selected cultivars and different kernel developmental stages of the X08 cultivar suggested that homogentisate phytyltransferase coding gene ( TgVTE2b) and ?-tocopherol methyltransferase coding gene ( TgVTE4) may be key players in tocopherol accumulation in the kernels of T. grandis. Subcellular localization assays showed that both TgVTE2b and TgVTE4 were localized to the chloroplast. We also identified candidate regulatory genes similar to WRI1 and DGAT1 in Arabidopsis that may be involved in the regulation of tocopherol biosynthesis. Our findings provide valuable genetic information for T. grandis using full-length transcriptomic analysis, elucidating the candidate genes and key regulatory genes involved in tocopherol biosynthesis. This information will be critical for further molecular-assisted screening and breeding of T. grandis genotypes with high tocopherol contents.

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