不同短裸甲藻毒素主幹在斑馬魚發育、心搏速率和c-fos表現上的相同與差異影響

Abstract

短裸甲藻毒素 (PbTxs)為含有兩大類化學架構差異的多環醚類毒素，皆由渦鞭毛藻的凱倫藻屬 (Karenia)中的藻種所產生，當此類有毒藻形成水華，會造成大量魚類和其他海洋生物的暴斃以及神經性貝毒的危害。為比較兩類PbTxs毒性上的差異，利用PbTx-1和 PbTx-2分別代表Type-A 和Type-B PbTx觀察對斑馬魚胚發育的影響。結果顯示浸泡於不同濃度的PbTxs下，會對斑馬魚胚的畸形率和存活率造成不同程度的影響，而PbTxs所造成的毒性乃源自於鈉離子的存在，且毒力可經由鈉離子通道抑制劑，例如河豚毒素 (TTX) 來抑制減弱。另外PbTx-1會導致心臟及神經有c-fos的大量表現，並使心跳速率不正常，但是這些異常現象在PbTx-2的處理中並不明顯。由於這些差異，說明了此兩類毒素主架構上的不同造成對不同鈉離子通道間的親和力有所差異，並產生了發育致畸時的某些不同表現。

Brevetoxins (PbTxs) are polyether toxins with two series of different chemical structures. They are produced by the red tide dinoflagellate species belonging to genus Karenia that cause massive fish and ocean creature fatalities and neurotoxic shellfish poisoning in human. To compare the toxicity between two types of PbTxs, I used PbTx-1 and PbTx-2 to represent the Type-A and Type-B PbTxs and observed their effects on zebrafish development. By the exposure of PbTxs at different concentrations to zebrafish embryo, I had determined the differential effects of PbTx-1 and PbTx-2 on embryonic abnormality and survival of zebrafish. In addition, the effects of PbTxs were demonstrated to be dependent on the presence of sodium and could be alleviated by the sodium channels blocker TTX. Lastly, I showed that PbTx-1, but less potent by PbTx-2 greatly enhanced the expression of c-fos in the heart and neuronal regions, which was correlated to the inhibition on the heart beats of zebrafish embryo. Those differential effects of PbTx-1 and PbTx-2 reflect the major structural difference between the two toxins which causes different affinity on sub-types of sodium channels that differentially expressed during development.