鮋亞目魚類毒素基因解序及演化分析

Venom gene determination and evolution in Scorpaenoidei

莊博舜(Po-Shun Chuang)

指導教授 ： 蕭仁傑

國立臺灣大學/理學院/海洋研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02850

摘要

棘鰭魚首目中有超過1200種的魚類被認定為具有毒性。其中鮋亞目(Scorpaenoidei)為這些有毒物種的主要類群之一，因此也被認定具有高度潛力可從中發現具有生物活性之分子。在本研究中，我們解序鮋亞目中三個物種的毒素基因，並且參考資料庫已有之序列，重建出此毒素基因可能的演化過程。根據cDNA推導出來之蛋白質序列，眉鬚鱗頭鮋(Sebastapistes strongia)、尖頭擬鮋(Scorpaenopsis oxycephala)及石狗公(Sebastiscus marmoratus)毒素的兩個次單元(subunit)長度約為700個胺基酸(698~703)，與過去在毒鮋屬(Synanceja)及簑鮋屬(Pterois)所發現之毒素相似。演化親緣關係的分析顯示，此毒素次單元的複製與分化應早於鮋亞目之分化，且此毒素基因可能普遍存在於整個鮋形目(Scorpaeniformes)的種類。除此之外，在簑鮋屬物種分化之前，可能發生了另外一次基因複製事件¬而產生了簑鮋屬的兩種毒素次單元。利用斑馬短鰭簑鮋(Dendrochirus zebra)的基因體，我們發現了三種不同的毒素基因序列，此結果暗示了在簑鮋亞科中假基因(pseudogene)存在的可能。此外，反轉錄定量聚合酶連鎖反應(RT-qPCR)的結果顯示，石狗公(Se. marmoratus)的背鰭硬棘具有相對最高的毒素基因表現，其他鰭的毒素表現則相對較少，而其表現量在各個不同組織的差異對應了其防禦性的功能─越容易受到攻擊的區域具有越高的毒素表現量。

關鍵字

鮋形目 ； 鮋亞目 ； 石狗公 ； 毒素基因

並列摘要

More than 1200 fish species among acanthomorpha might be venomous. Scorpaenoidei, a diverse suborder of ray-finned fish, is a hotspot of venomous fish and possesses a large pool of potential bioactive molecules. In the present study we determined the venom genes from three scorpaenoid fishes and reconstructed their evolutionary relationship. The deduced amino acid sequences of two venom subunits in Sebastapistes strongia, Scorpaenopsis oxycephala, and Sebastiscus marmoratus are about 700 a.a. (698~703 a.a.), corresponding to the size of stonefish and lionfish venoms. Phylogenetic analysis shows that the two gene subunits were duplicated prior to the speciation of Scorpaenoidei and may be common to the whole Scorpaeniform family. In addition, another gene duplication event occurred before the speciation of lionfish (Pteroinae), thus generating the two venom subunits in the genus Pterois. The venom genes determined from the genomic DNA of Dendrochirus zebra show three types of venom genes in the genome, implying that a pseudogene may present in Pteroinae. The expression pattern of the venom genes in different tissues of Se. marmoratus were evaluated by RT-qPCR, respectively. The dorsal spines were found to be the most venomous part of the fish, while lesser amounts of the venom genes were detected in other fins. The venom expression pattern seems to reflect the defensive purpose of the venom, with the most easily attacked part expressing the highest venom levels.

並列關鍵字

Scorpaeniformes ； Scorpaenoidei ； scorpionfish ； rockfish ； venom gene

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