The Adaptive Machineries for Acid and Sulfate Regulations in Hydrothermal Vent Crab

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基本資料

Project title

Code/計畫編號

MOST107-2621-M019-004

Translated Name/計畫中文名

熱泉怪方蟹對酸與硫化物的適應調控機制

Project Coordinator/計畫主持人

Yi-Ta Shao

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

曾庸哲

Department/Unit

Institute of Marine Biology

Website

https://www.grb.gov.tw/search/planDetail?id=12671176

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

01-07-2019

Bugetid/研究經費

1000千元

ResearchField/研究領域

大氣科學

深海熱泉支持著獨特的生態系統，其中包含了從微生物到脊椎動物豐富的生物多樣性。為了要在如此極端的環境生存，生物發展出特殊的形態和生理機制，以適應高溫、高硫、低氧、高二氧化碳和低pH值的棲地。台灣北方的龜山島的淺海熱泉即是這類生物的代表棲地。龜山島熱泉的是一個高溫(76-116℃)、極度酸化(pH 1.5-2.5)的海底熱泉系統；此外，此處的排水含有大量的硫化物。在如此特殊的環境中，只有少數物種可以生存。例如在噴口附近的烏龜怪方蟹(Xenograpsus testudinatus)，是唯一生存於此的後生動物。對甲殼類動物而言，鰓是參與細胞外離子與酸鹼平衡的主要器官，鰓表面的離子調節上皮所具有的離子主動/被動運輸機制在演化則相當的保守。在最近的研究中，我們找到烏龜怪方蟹主要的酸價與硫的排除通道。與脊椎動物相似，烏龜怪方蟹的鰓表皮細胞上有眾多的NKA、VHA與AE蛋白通道，這些通道幫浦在怪方蟹所有的鰓對上都有存在，並維持了烏龜怪方蟹的酸鹼平衡功能。此外，龜山島熱泉對生物的生理挑戰不僅是酸鹼調節，同時也包括了如何克服環境硫化氫的毒性。前期的研究中發現，怪方蟹可能利用將牛磺酸合成硫代牛磺酸的過程減低硫的毒性，並將其從鰓表皮的運輸蛋白(SLCs)排出體外。我們普遍認為，在熱泉系統中的甲殼類應該具有比其他物種更好的控制硫化物與酸鹼恆定性。然而，造就這種極端環境下的動態平衡能力的機制尚不清楚。此外，日本九州鹿兒島南方海域也存在著與龜山島相似的淺海熱泉，在鹿兒島的熱泉生態系也發現與烏龜怪方蟹相似的種類。然而，此海域環境酸鹼值卻明顯低於龜山島海域。藉由比較在這兩個不同環境下生活的怪方蟹是否有不同的適應機制，可望了解酸鹼或硫化物調控的次主動運輸幫浦蛋白的演化關係。酸鹼與離子調節機制對甲殼類來說，不僅是一個物種演化的現象，在物種與生態的永續也至關重要。隨著溫室氣體的排放，除了導致海洋的酸化也造成局部海域的硫濃度上生。酸化的海水已經知道會嚴重影響無脊椎動物的生理與發育，然而，甲殼類面對酸化環境的調控能力與適應機制則上不為人知。利用烏龜怪方蟹為模式動物，本計畫主軸在研究海底熱泉動物適應強酸性與高硫化物環境的特化生理機制，以及熱泉動物與非熱泉動物的生理演化關係。同時，我們希望藉由這個研究，說明一般海洋甲殼類生物在面臨海洋酸化時的可能適應能力與所需付出的代價。 Deepsea hydrothermal vent systems support a special ecosystem. To survive in these extreme habitats, vent associated organisms show a range of morphological and physiological adaptations to cope with challenging environmental conditions including temperature, metallic sulfides, anoxia, hypercapnia and extremely lower pH. This shallow water hydrothermal vent system has been described as one of the most acidic vents in the world, discharging water with a high content of elemental sulfur particles, temperatures of 76-116°C and a minimum pH of 1.5-2.5. In such drastic environment, hydrothermal vent brachyuran crab, Xenograpsus testudinatus, is the only metazoan species that is endemic to the areas. The gills of Crustaceans are the major organ involved in extracellular ion and acid-base homeostasis, equipped with an efficient ion regulatory machinery that shows evolutionary conserved features compared to ion regulatory epithelia in crustaceans. As well as, the ubiquitous NKA, VHA and AE localized on gill membranes that created the electro-chemical gradient and mediate ionic and pH homeostasis in crustaceans. Moreover, the physiological challenges from Kueishan Island hydrothermal vent environment are not only acid-base regulation, but also the toxicity of H2S. Previous studies inferred that X. testudinatus gills are capable to catabolize hypotaurine and S2 thus synthesize thiotaurine to reduce cellular toxicity. In addition, relative highly expressions of sulfur transport-related transcript, solute carrier family 26A11 (SLC26A11), was found in native individuals as well. It implies that sulfide may be oxidized to sulfate then transported by SLC26A11 in gill epithelium. In generally thought, the crustaceans habit in the hydrothermal vents areas should have better and more capacity of both acid-base and sulfide oxidation homeostasis. Nevertheless, the mechanism in those special animals that enhance the homeostasis abilities under such extreme environment is still unclear. In near coast area of Kagoshima (Japan), a similar shallow water hydrothermal vent system was discovered with a vent brachyuran crab species related to X. testudinatus; however, the pH level of the Kagoshima hydrothermal vent was far less that what was found in Kueishan Island. The adaption mechanisms of those two species of crab in different environments may be the key to understand the physiological evolution of those active transporters involved in the ions and soulfate regulation. The acid-base and ions regulation mechanisms of crustaceans are not only a key for species evolution, but also important for the ecological sustainability in the furture. The continual green house emission has resulted in a steady increase acidity of the oceans, and has been known that influences invertebrates dramatically. However, the possible mechanism of crustaceans to adapt further acidified seawater was less known. Uisng X. testudinatus as model animals, this study aims to reveal the specialized physiological mechanism of hydrothermal vent creatures adapting to the low pH, but high sulfide oxidation concentration, environment. As well as, the physiological evolution of those secondary active transporters involved in the ions homeostasis between vent crustaceans and non-vent crustaceans. Moreover, we aimed to kown the possible adaptation and cost of the marine crustaceans when they face to the ocean acidifcaiotn in the furture.

Keyword(s)

熱泉怪方蟹
離子調控
鈉鉀幫浦
運輸蛋白
海洋酸化
hydrothermal vent brachyuran crab
ions regulation
sodium pump
solute carrier
ocean acidification

DSpace CRIS

The Adaptive Machineries for Acid and Sulfate Regulations in Hydrothermal Vent Crab

基本資料

Description