The compounds of sterols such as C27 ,C2s ,C29 and C30 are recorded from C-8 core of the Chukchi Sea. The double bond position is located at 5-, 5,22 as well as 22-,24-. The compound of sterols such as C27 ,C28 ,C29 a...The compounds of sterols such as C27 ,C2s ,C29 and C30 are recorded from C-8 core of the Chukchi Sea. The double bond position is located at 5-, 5,22 as well as 22-,24-. The compound of sterols such as C27 ,C28 ,C29 are recorded from B2-9 core of the Bering Sea. The double bond position is located at 5-, 5, 22 as well as 22. The composition characteristics of sterols indicate that the substance is mainly contributed by the terrigenous origin and marine silicate organisms. The results are also suggest that the record of abnormal sterols from the surface sediments （2 -0 era）in the Chukchi Sea and the Bering Sea represent the period from 1980s to the late 1990s. The strong signal of the Arctic warming is preserved in the sediments, which indicates the eco - environmental change responding to climatic effect of circumjacent.展开更多
Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not...Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not well be established.Six cyanobacterial Microcystis strains(including both unicellular and colonial ones)were employed to estimate the influences of their physiological traits and the composition of extracellular polymeric substances(EPS)on colony or aggregate formation.Results show that raising the number of the photosynthetic reaction center and light-harvesting antenna in the PSII and reducing the growth rate were the major physiological strategies of Microcystis to produce excess EPS enhancing colony formation.Tightly bound EPS(T-EPS)was responsible for colony formation,which approximately accounted for 50%of the total amount of EPS.Five fluorescent components(protein-,tryptophan-,and tyrosine-like components and two humic-like components)were found in the T-EPS,although the amounts of these components varied with strains.Importantly,colonial strains contained much higher tyrosine-like substances than unicellular ones.We suggest that tyrosine-like substances might serve as a crosslinking agent to connect other polymers in EPS(e.g.,proteins or polysaccharides)for colony formation.Our findings identified key physiological traits and chemical components of EPS for colony formation in Microcystis,which can contribute to a better understanding on the formation of Microcystis blooms.展开更多
文摘The compounds of sterols such as C27 ,C2s ,C29 and C30 are recorded from C-8 core of the Chukchi Sea. The double bond position is located at 5-, 5,22 as well as 22-,24-. The compound of sterols such as C27 ,C28 ,C29 are recorded from B2-9 core of the Bering Sea. The double bond position is located at 5-, 5, 22 as well as 22. The composition characteristics of sterols indicate that the substance is mainly contributed by the terrigenous origin and marine silicate organisms. The results are also suggest that the record of abnormal sterols from the surface sediments （2 -0 era）in the Chukchi Sea and the Bering Sea represent the period from 1980s to the late 1990s. The strong signal of the Arctic warming is preserved in the sediments, which indicates the eco - environmental change responding to climatic effect of circumjacent.
基金Supported by the National Natural Science Foundation of China(No.32071569)the Scientific Instruments and Equipment Development Project+2 种基金Chinese Academy of Sciences,2020(No.YJKYYQ20200048)the Fundamental Research Funds for the Central Universities(No.B210202010)the China Postdoctoral Foundation(No.2020M681472)。
文摘Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not well be established.Six cyanobacterial Microcystis strains(including both unicellular and colonial ones)were employed to estimate the influences of their physiological traits and the composition of extracellular polymeric substances(EPS)on colony or aggregate formation.Results show that raising the number of the photosynthetic reaction center and light-harvesting antenna in the PSII and reducing the growth rate were the major physiological strategies of Microcystis to produce excess EPS enhancing colony formation.Tightly bound EPS(T-EPS)was responsible for colony formation,which approximately accounted for 50%of the total amount of EPS.Five fluorescent components(protein-,tryptophan-,and tyrosine-like components and two humic-like components)were found in the T-EPS,although the amounts of these components varied with strains.Importantly,colonial strains contained much higher tyrosine-like substances than unicellular ones.We suggest that tyrosine-like substances might serve as a crosslinking agent to connect other polymers in EPS(e.g.,proteins or polysaccharides)for colony formation.Our findings identified key physiological traits and chemical components of EPS for colony formation in Microcystis,which can contribute to a better understanding on the formation of Microcystis blooms.
