Genetic mechanisms of bone digestion and nutrient absorption in the bone-eating worm Osedax japonicus inferred from transcriptome and gene expression analyses.
Genetic mechanisms of bone digestion and nutrient absorption in the bone-eating worm Osedax japonicus inferred from transcriptome and gene expression analyses.
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DOI：
10.1186/s12862-016-0844-4
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发表时间：
2017-01-13
影响因子：
3.4
通讯作者：
Fujiwara Y
中科院分区：
文献类型：
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作者：
Miyamoto N;Yoshida MA;Koga H;Fujiwara Y
Osedax(环节动物纲，Siboglinidae)属的食骨蠕虫通过获得一种名为根的新特征来适应鲸鱼坠落的环境，根可以分支并穿透到凹陷的骨骼中。这种蠕虫缺乏消化道和张口，有人认为Osedax通过酸化和根部酶的分泌来降解脊椎动物的骨骼和吸收营养。根组织中的共生细菌可能在Osedax的新陈代谢中起到关键作用。然而，负责骨消化和营养吸收的分子机制和细胞仍不清楚，关于Osedax和共生菌之间代谢相互作用的信息也有限。我们比较了来自以下组织的三个不同的RNA样本：树干 + 触须，根 + 卵形，和幼虫 + 雄性。PFAM结构域浓缩分析表明，与总转录组相比，蛋白酶和转运蛋白相关基因在根 + 卵子特异基因中得到了丰富。通过有针对性的基因注释，我们发现与其他无脊椎动物相比，Osedax中的基因家族扩大导致了显着数量的基质金属蛋白酶(MMPs)基因。其中12个Osedax基质金属蛋白酶基因在根表皮细胞中表达。编码各种转运蛋白的基因，包括氨基酸、寡肽、碳酸氢盐和硫酸盐/羧酸转运蛋白，也在根表皮细胞中表达。此外，氨基酸和其他代谢物转运蛋白基因在细菌细胞中表达。这些蛋白水解酶和转运蛋白基因最早是在幼根发育阶段的根组织中表达的。根表皮中各种蛋白水解酶和转运蛋白基因的表达支持根表皮细胞负责骨消化和随后的营养吸收的理论。转运蛋白基因在宿主细菌细胞中的表达表明Osedax与共生菌之间存在代谢相互作用。本文的在线版本(doi：10.1186/s12862-0160844-4)包含补充材料，授权用户可以使用。
Bone-eating worms of the genus Osedax (Annelida, Siboglinidae) have adapted to whale fall environments by acquiring a novel characteristic called the root, which branches and penetrates into sunken bones. The worms lack a digestive tract and mouth opening, and it has been suggested that Osedax degrade vertebrate bones and uptake nutrients through acidification and secretion of enzymes from the root. Symbiotic bacteria in the root tissue may have a crucial role in the metabolism of Osedax. However, the molecular mechanisms and cells responsible for bone digestion and nutrient uptake are still unclear, and information on the metabolic interaction between Osedax and symbiotic bacteria is limited. We compared transcriptomes from three different RNA samples from the following tissues: trunk + palps, root + ovisac, and larva + male. A Pfam domain enrichment analysis revealed that protease- and transporter-related genes were enriched in the root + ovisac specific genes compared with the total transcriptome. Through targeted gene annotation we found gene family expansions resulting in a remarkably large number of matrix metalloproteinase (mmp) genes in the Osedax compared with other invertebrates. Twelve of these Osedax mmp genes were expressed in the root epidermal cells. Genes encoding various types of transporters, including amino acid, oligopeptide, bicarbonate, and sulfate/carboxylate transporters, were also expressed in root epidermal cells. In addition, amino acid and other metabolite transporter genes were expressed in bacteriocytes. These protease and transporter genes were first expressed in root tissues at the juvenile stage, when the root starts to develop. The expression of various proteinase and transporter genes in the root epidermis supports the theory that the root epidermal cells are responsible for bone digestion and subsequent nutrient uptake. Expression of transporter genes in the host bacteriocytes suggests the presence of metabolic interaction between Osedax and symbiotic bacteria. The online version of this article (doi:10.1186/s12862-016-0844-4) contains supplementary material, which is available to authorized users.