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南海冷泉平端深海偏顶蛤(Bathymodiolus platifrons)主要生化成分与能量代谢的研究
郭欣雨
学位类型硕士
导师李超伦
2017-05-24
学位授予单位中国科学院大学
学位授予地点北京
学位专业海洋生态学
关键词平端深海偏顶蛤 生化组成 代谢组 冷泉 南海
其他摘要      冷泉由海底地质构造活动引起的含天然气水合物的流体的溢出,深海冷泉环境的主要特征为低温和高甲烷浓度。尽管冷泉环境对大多数多细胞生物的生存不利,但仍有少数度多细胞生物在深海冷泉成功生存并繁衍出巨大的生物量。Bathymodiolus属贻贝就是广泛分布于全球深海冷泉和热液生态系统的优势种,在深海化能生态系统的物质循环和能量流动中起着重要作用。其鳃内具有共生的化能自养细菌,能够利用环境中的甲烷或硫化氢氧化释放的能量合成有机物,为贻贝提供食物来源。
       本研究以我国南海北部冷泉的主要优势种平端深海偏顶蛤(Bathymodiolus platifrons)为研究对象,采用常规生化测定方法,研究了其主要生化成分和氨基酸组成的特征,并就特定组织中主要生化成分的含量与生活在热液区的平端深海偏顶蛤和近岸的远东偏顶蛤(Modiolus kurilensis)进行了对比,探究特殊生境对平端深海偏顶蛤生化组成的影响。结果表明,南海冷泉平端深海偏顶蛤软体部含水量84.28%,粗蛋白含量7.18%,粗脂肪含量1.23%,糖类含量2.75%,与已报道的深海贝类组成相近。虽然主要生化成分含量在三种贻贝的鳃、外套膜、闭壳肌和消化腺四个组织中总体差异不大,但是冷泉平端深海偏顶蛤和热液平端深海偏顶蛤的外套膜糖类含量(25.20%、30.66%)显著高于远东偏顶蛤(6.97%)(P<0.05),这表明平端深海偏顶蛤的主要储存物质为外套膜中的糖类。在氨基酸组成上,冷泉平端深海偏顶蛤鳃中氨基酸总量为44.55%(干重),外套膜中为34.83%(干重),其中必需氨基酸分别占比41.73%和40.52%,总体与其他贝类相似。然而,在平端深海偏顶蛤中,与渗透压调节相关的甘氨酸和与硫代谢相关的牛磺酸含量较高,这与其适应深海高盐度高硫化氢浓度的环境相关。
       此外,本研究还使用液相色谱-质谱联用技术分别对甲烷培养和非甲烷培养不同时间的平端深海偏顶蛤的外套膜进行代谢组学研究,分别分析了相同时间甲烷培养与非甲烷培养组平端深海偏顶蛤外套膜的差异代谢物水平的变化及相关代谢途径以及一个时间序列上甲烷培养与非甲烷培养组平端深海偏顶蛤外套膜的差异代谢物水平变化及相关代谢途径,试图探究平端深海偏顶蛤在饥饿状况下对营养物质的利用。代谢组学分析表明,在平端深海偏顶蛤饥饿培养期间,能量代谢途径的中间代谢物琥珀酸和乳酸在甲烷培养组含量升高,表明甲烷组平端深海偏顶蛤体内保持了高的能量代谢水平,而葡萄糖含量没有显著变化,说明其能量来源可能是脂类代谢和氨基酸代谢的中间产物。脂类代谢方面,硬脂酸的含量随时间显著下降,表明脂肪酸的合成代谢下调。软脂酸的含量则在24 h和72 h有上升,随后下降,可能是在饥饿初期贻贝分解了部分甘油三酯,脂肪酸含量上升,之后由于消耗而下降。非甲烷培养组乙酰肉碱含量的显著下降和甘油-3-磷酸含量的显著上升表明,在饥饿期间,平端深海偏顶蛤减缓了储存脂类的合成,并开始使用储存的甘油三酯。仅有少数自由氨基酸的含量发生变化说明在饥饿10天期间内,平端深海偏顶蛤没有分解蛋白质作为能量。
;        Cold seep is the overflow of fluid containing gas hydrate caused by seafloor geological tectonic activities. The main characteristics of cold seep environment are low-temperature and high-concentrate methane. Although it is unsuitable for most of multicellular organisms, there are still few organisms inhabiting cold seep with a huge biomass. Bathymodiolus mussels which are widely distributed in the cold seep and hydrothermal vent ecosystems around the world seafloor as the key species,act as an important role in material cycle and energy flow of deep-sea chemosynthesis ecosystems. A symbiosis relationship between mussels and chemoautotrophic bacteria in their gills provides food for mussels.
       Conventional biochemical determination methods were used to study biochemical composition of Bathymodiolus platifrons at the South China Sea cold seep and the comparison among mussels at cold seep and hydrothermal vent as well as offshore mussel Modiolus kurilensis were discussed. The proportion of water, crude protein, lipid and glycogen of B. platifrons is 84.28, 7.18, 1.23 and 2.75%, respectively, which are similar to that of reported deep-sea mussels. Glycogen content in mantle of seep B. platifrons (25.20%) is significantly higher than that of offshore mussel M. kurilensis (6.97%) (P<0.05), but close to vent B. platifrons (30.66%), indicating that glycogen in mantle is the energy reserves. The total amino acid content in gill and mantle of seep B. platifrons is 44.55 and 34.83% of dry weight, in which essential amino acid content account for 41.73 and 40.52%, respectively. However, the content of glycine and taurine which are related to osmoregulation and sulfur metabolism are higher than off-shore bivalves, which may be adaption to the environment.
       In addition, significantly different metabolites and metabolic pathways were analysed between methane and methane-free cultivating B. platifrons as well as among different cultivating time by LC-MS, in order to investigate the metabolism of nutrition during starvation. We find that during the starvation of B. platifrons, succinate and lactate increased in methane-cultivating group, indicating that the energy metabolism level remained high in this group. The intermediate products of lipid metabolism and amino acid metabolism maybe the energy source of mussels, since the level of glucose didn’t change significantly. Stearic acid decreased which means fatty acid biosynthesis decreased. Palmitic acid increased on 24 h and 72 h but decreased afterwards, illustrating that at the beginning of starvation, triglycerides were broken down for fuel. In methane-free cultivating groups, acetyl-carnitine decreased and glycerol-3-phosphate increased, indicating that lipid biosynthesis of mussels slows down, triglycerides are exploited during starvation. Only few free amino acids fluctuated during starvation, which means that protein is not decomposed for fuel.
学科领域海洋科学其他学科
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/136620
专题海洋生态与环境科学重点实验室
作者单位1.中国科学院海洋研究所
2.中国科学院大学
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郭欣雨. 南海冷泉平端深海偏顶蛤(Bathymodiolus platifrons)主要生化成分与能量代谢的研究[D]. 北京. 中国科学院大学,2017.
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