Statistics of full-length sequence data.

BackgroundThe differentiation and maturation of proglottids constitute the basis for the growth and development of tapeworms. However, little is known about the molecular mechanisms underlying the differentiation of the proglottids of Spirometra mansoni.Methodology/Principal findingsHere, the nanopore sequencing method was used to perform full-length transcriptomic analysis of 3 types of proglottids (scolex-neck-immature proglottids, SNIPs; mature proglottids, MPs; and gravid proglottids, GPs) of S. mansoni. Comparative transcriptomic analysis revealed that pyruvate kinase (PK) is a key gene affecting segmental differentiation. The PK family members of S. mansoni (SmPKs) were subsequently screened and systematically analysed. Moreover, a representative member, SmPK1, was chosen for cloning, expression and functional characterization. A total of 4,486 differentially expressed genes (DEGs) were identified across the 3 proglottid types. GO analysis revealed that the DEGs were enriched mostly in metabolism-related terms. KEGG enrichment analysis and GSEA further revealed that the degree of enrichment of the glycolysis pathway gradually increased as the segments developed and matured. Protein‒protein interaction (PPI) analysis confirmed that PK occupies a central position among energy metabolism-related genes and plays key roles in glycolysis. On the basis of the omics data, 4 SmPKs were identified. Phylogenetic analysis revealed that SmPKs have undergone varying degrees of evolution and exhibit high diversity. The optimal reaction conditions for recombinant SmPK1 (rSmPK1) were 37 °C and pH 8.0, and the addition of K ⁺ /Mg² ⁺ significantly enhanced its catalytic activity. Tannic acid significantly inhibited the activity of SmPK1 in vitro, reduced the production of pyruvate, and forced the organism to compensate for the energy supply through rapid lipolysis and delayed glycogen depletion, thereby affecting energy metabolism in tapeworms.ConclusionsThis study provides the first comprehensive characterization of gene expression profiles across different proglottids of S. mansoni. PK plays a pivotal role in proglottid differentiation, and this finding lays the foundation for further exploration of the differentiation mechanism of segments in tapeworms.**研究背景** 节片（proglottid）的分化与成熟是绦虫生长发育的基础，但目前对于曼氏迭宫绦虫（Spirometra mansoni）节片分化的分子机制仍知之甚少。 **研究方法与主要结果** 本研究采用纳米孔测序（nanopore sequencing）技术，对曼氏迭宫绦虫的3种节片——头颈部未成熟节片（scolex-neck-immature proglottids, SNIPs）、成熟节片（mature proglottids, MPs）以及孕节片（gravid proglottids, GPs）——进行全长转录组分析。比较转录组分析显示，丙酮酸激酶（pyruvate kinase, PK）是影响节片分化的关键基因。随后，研究人员筛选并系统分析了曼氏迭宫绦虫的PK家族成员（SmPKs）。此外，选取家族代表性成员SmPK1进行克隆、表达及功能表征。在3种节片中共鉴定出4486个差异表达基因（differentially expressed genes, DEGs）。基因本体（Gene Ontology, GO）富集分析显示，差异表达基因主要富集于代谢相关通路术语。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）富集分析及基因集富集分析（Gene Set Enrichment Analysis, GSEA）进一步显示，随着节片发育成熟，糖酵解通路的富集程度逐渐升高。蛋白质相互作用（protein-protein interaction, PPI）分析证实，PK在能量代谢相关基因中占据核心位置，并在糖酵解过程中发挥关键作用。基于组学数据，本研究共鉴定出4个SmPKs。系统发育分析显示，SmPKs经历了不同程度的进化，且呈现出较高的多样性。重组SmPK1（rSmPK1）的最适反应条件为37℃、pH 8.0，K⁺/Mg²⁺的添加可显著增强其催化活性。鞣酸可在体外显著抑制SmPK1的活性，减少丙酮酸的生成，迫使虫体通过快速脂肪分解与延迟糖原消耗来补偿能量供应，进而影响绦虫的能量代谢。 **研究结论** 本研究首次全面解析了曼氏迭宫绦虫不同节片的基因表达谱。PK在节片分化中发挥关键作用，该发现为进一步探索绦虫节片分化机制奠定了基础。