globalchange  > 影响、适应和脆弱性
DOI: 10.1111/gbi.12165
Scopus记录号: 2-s2.0-84978835308
论文题名:
Early sponges and toxic protists: possible sources of cryostane, an age diagnostic biomarker antedating Sturtian Snowball Earth
作者: Brocks J.J.; Jarrett A.J.; Sirantoine E.; Kenig F.; Moczydłowska M.; Porter S.; Hope J.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2016
卷: 14, 期:2
起始页码: 129
结束页码: 149
语种: 英语
Scopus关键词: biological marker ; cholestane derivative ; biochronology ; biomarker ; chemical analysis ; Ediacaran ; fossil record ; microfossil ; Proterozoic ; sponge ; supercontinent ; taxonomy ; toxic organism ; animal ; Arizona ; fossil ; Lepidoptera ; parasitology ; sponge (Porifera) ; Sweden ; Western Australia ; Animals ; Arizona ; Biomarkers ; Cholestanes ; Fossils ; Lepidoptera ; Porifera ; Sweden ; Western Australia ; Arizona ; Australia ; Officer Basin ; Sweden ; United States ; Western Australia ; Animalia ; Eukaryota ; Protista
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences ; Environmental Science: General Environmental Science ; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: The period 800-717 million years (Ma) ago, in the lead-up to the Sturtian Snowball glaciation, saw an increase in the diversity of eukaryotic microfossils. To afford an independent and complementary view of this evolutionary period, this study presents the distribution of eukaryotic biomarkers from three pre-Sturtian successions across the supercontinent Rodinia: the ca. 780 Ma Kanpa Formation of the Western Australian Officer Basin, the ca. 800-740 Ma Visingsö Group of Sweden, and the 740 Ma Chuar Group in Arizona, USA. The distribution of eukaryotic steranes is remarkably similar in the three successions but distinct from all other known younger and older sterane assemblages. Cholestane was the only conventional structure, while indigenous steranes alkylated in position C-24, such as ergostane, stigmastane, dinosterane and isopropylcholestane, and n-propylcholestane, were not observed. This sterane distribution appears to be age diagnostic for the pre-Sturtian Neoproterozoic. It attests to the distinct evolutionary state of pre-Snowball eukaryotes, pointing to a taxonomic disparity that was still lower than in the Ediacaran (635-541 Ma). All three basins also show the presence of a new C28 sterane that was tentatively identified as 26-methylcholestane, here named cryostane. The only known extant organisms that can methylate sterols in the 26-position are demosponges. This assignment is plausible as molecular clocks place the appearance of the earliest animals into the pre-Sturtian Neoproterozoic. The unusual 26-methylsterol may have protected sponges, but also other eukaryotes, against their own membranolytic toxins. Some protists release lytic toxins to deter predators and kill eukaryotic prey. As conventional membrane sterols can be the site of attack for these toxins, sterols with unusual side-chain modification protect the cell. This interpretation of cryostane supports fossil evidence of predation in the Chuar Group and promotes hypotheses about the proliferation of eukaryophagy in the lead-up to the Cryogenian. © 2015 John Wiley & Sons Ltd.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85114
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作者单位: Research School of Earth Sciences, The Australian National University, Canberra, ACT, Australia; Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, USA; Department of Earth Sciences, Palaeobiology, Uppsala University, Uppsala, Sweden; Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA, USA

Recommended Citation:
Brocks J.J.,Jarrett A.J.,Sirantoine E.,et al. Early sponges and toxic protists: possible sources of cryostane, an age diagnostic biomarker antedating Sturtian Snowball Earth[J]. Geobiology,2016-01-01,14(2)
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