Comparative immunological study of the snail Physella acuta (Hygrophila, Pulmonata) reveals shared and unique aspects of gastropod immunobiology.
Comparative immunological study of the snail Physella acuta (Hygrophila, Pulmonata) reveals shared and unique aspects of gastropod immunobiology.
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对蜗牛 Physella acuta（Hygrophila、Pulmonata）的比较免疫学研究揭示了腹足动物免疫生物学的共同和独特方面。
DOI：
10.1016/j.molimm.2018.05.029
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发表时间：
2018
影响因子：
3.6
通讯作者：
Adema,CoenM
中科院分区：
文献类型：
--
作者：
Schultz,JonathanH;Bu,Lijing;Adema,CoenM
为了拓展比较钉螺免疫学的研究视角，本研究选择了淡水钉螺Physella acuta.通过对Physella acuta的分析，可以在科的水平上比较光滑Biomphalaria的免疫特征，Physella acuta属于Physidae的分类姊妹科，Biomphalaria grarata是经常被用来解释一般腹足类免疫的模式蜗牛。为了获得组成免疫序列和诱导免疫序列，用454焦磷酸测序技术记录了一只尖叶泡菜个体、注射细菌后12 h的革兰氏阳性和一只假暴露的钉螺的转录本。组装产生了一个包含24,288个转录本的组合参考转录组。此外，还获得了基因组Illumina读数(∼覆盖15倍)。对两个Macin样抗菌肽(AMPs)、12个Aplysianins、四个LBP/BPI和三个Phyalysins的转录本的恢复表明，尖叶叶霉具有与光滑生物相似的抗菌防御组织，相比之下，适度的AMP武库和一系列不同的抗菌蛋白形成了鲜明的对比。在所有七个尖叶泡菜PGRP转录本中都缺乏预测的跨膜结构域，这支持腹足类不使用细胞结合的PGRP受体的观点，这不同于蜕皮动物无脊椎动物，但与哺乳动物(脊椎动物后口动物)相似。由一个大的FREP基因家族的体细胞突变产生的免疫凝集素FREP(包括免疫球蛋白超家族结构域和纤维蛋白原结构域)的序列多样化被认为是平面虫科所独有的；尖叶疫霉只发现了两个真正的FREP基因，这些基因并不多样化。此外，这里证实可以感染这两种钉螺的扁虫寄生虫帕氏棘口吸虫，在暴露后2、4和8天并没有像以前从光滑生物体内观察到的那样，从尖锐疫霉那里引起FREP蛋白的大量表达。Physella acutaReference转录组还发现了24个编码蛋白质的独特转录本，由一个单一的纤维蛋白原相关结构域(FREDS)组成，具有一个短的N末端序列，编码一个信号肽、跨膜结构域或没有预测的特征。基于相似序列在双壳类软体动物免疫中的暗示，尖叶泡菜FReD是候选的免疫基因。总体而言，对姐妹科蜗牛的比较分析阐明了分类群特异性免疫特征的可能性，对战略性选择的物种的调查将提供对腹足类免疫的更全面的看法。
The freshwater snailPhysella acutawas selected to expand the perspective of comparative snail immunology. Analysis ofPhysella acuta,belonging to the Physidae, taxonomic sister family to Planorbidae, affords family-level comparison of immune features characterized fromBiomphalaria glabrata,the model snail often used to interpret general gastropod immunity. To capture constitutive and induced immune sequences, transcriptomes of an individualPhysella acutasnail, 12 h post injection with bacteria (Gram –/+) and one sham-exposed snail were recorded with 454 pyrosequencing. Assembly yielded a combined reference transcriptome containing 24,288 transcripts. Additionally, genomic Illumina reads were obtained (∼15-fold coverage). Recovery of transcripts for two macin-like antimicrobial peptides (AMPs), 12 aplysianins, four LBP/BPIs and three physalysins indicated thatPhysella acutashares a similar organization of antimicrobial defenses withBiomphalaria glabrata, contrasting a modest AMP arsenal with a diverse set of antimicrobial proteins. The lack of predicted transmembrane domains in all sevenPhysella acutaPGRP transcripts supports the notion that gastropods do not employ cell-bound PGRP receptors, different from ecdysozoan invertebrates yet similar to mammals (vertebrate deuterostomes). The well-documented sequence diversification byBiomphalaria glabrataFREPs (immune lectins comprising immunoglobulin superfamily domains and fibrinogen domains), resulting from somatic mutations of a large FREP gene family is hypothesized to be unique to Planorbidae;Physella acutarevealed just two bonafide FREP genes and these were not diversified. Furthermore, the flatworm parasiteEchinostoma paraensei, confirmed here to infect both snail species, did not evoke fromPhysella acutathe abundant expression of FREP proteins at 2, 4 and 8 days post exposure that was previously observed fromBiomphalaria glabrata. ThePhysella acutareference transcriptome also revealed 24 unique transcripts encoding proteins consisting of a single fibrinogen-related domain (FReDs), with a short N-terminal sequence encoding either a signal peptide, transmembrane domain or no predicted features. ThePhysella acutaFReDs are candidate immune genes based on implication of similar sequences in immunity of bivalve molluscs. Overall, comparative analysis of snails of sister families elucidated the potential for taxon-specific immune features and investigation of strategically selected species will provide a more comprehensive view of gastropod immunity.