Sedimentary 12-
            <i>n</i>
            -Propylcholestanes, Molecular Fossils Diagnostic of Marine Algae

Moldowan, J. Michael; Fago, Frederick J.; Lee, Cathy Y.; Jacobson, Steven R.; Watt, David S.; Slougui, Nacer-Eddine; Jeganathan, Alwarsamy; Young, Douglas L.

doi:10.1126/science.247.4940.309

Cited by 281 publications

(86 citation statements)

References 24 publications

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“…The late emergence of algal 24-n-propylidenecholesterol (24-npc) is also consistent with the geological record. Although the C 30 sterane contents of petroleum and source rocks remain very low in the Cambrian to Early Ordovician, the ratio of 24-isopropylcholestanes to 24-n-propylcholestanes remains high (39)(40)(41), consistent with a primary source from sponges. A rise in 24-n-propylcholestane contents thereafter suggests that algae sources appeared between the Early Ordovician and Devonian (40).…”

Section: Stramenopiles IImentioning

confidence: 77%

“…Although the C 30 sterane contents of petroleum and source rocks remain very low in the Cambrian to Early Ordovician, the ratio of 24-isopropylcholestanes to 24-n-propylcholestanes remains high (39)(40)(41), consistent with a primary source from sponges. A rise in 24-n-propylcholestane contents thereafter suggests that algae sources appeared between the Early Ordovician and Devonian (40). We therefore conclude that sponges and/or foraminiferans are better candidates for 24-n-propylcholestane in the Neoproterozoic, which requires a reappraisal as to whether "npc/ipc" ratios are necessary for identifying sponge biomarkers.…”

Section: Stramenopiles IImentioning

confidence: 77%

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Sterol and genomic analyses validate the sponge biomarker hypothesis

Gold

Grabenstatter

Mendoza

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

119

121

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Molecular fossils (or biomarkers) are key to unraveling the deep history of eukaryotes, especially in the absence of traditional fossils. In this regard, the sterane 24-isopropylcholestane has been proposed as a molecular fossil for sponges, and could represent the oldest evidence for animal life. The sterane is found in rocks ∼650-540 million y old, and its sterol precursor (24-isopropylcholesterol, or 24-ipc) is synthesized today by certain sea sponges. However, 24-ipc is also produced in trace amounts by distantly related pelagophyte algae, whereas only a few close relatives of sponges have been assayed for sterols. In this study, we analyzed the sterol and gene repertoires of four taxa (Salpingoeca rosetta, Capsaspora owczarzaki, Sphaeroforma arctica, and Creolimax fragrantissima), which collectively represent the major living animal outgroups. We discovered that all four taxa lack C 30 sterols, including 24-ipc. By building phylogenetic trees for key enzymes in 24-ipc biosynthesis, we identified a candidate gene (carbon-24/28 sterol methyltransferase, or SMT) responsible for 24-ipc production. Our results suggest that pelagophytes and sponges independently evolved C 30 sterol biosynthesis through clade-specific SMT duplications. Using a molecular clock approach, we demonstrate that the relevant sponge SMT duplication event overlapped with the appearance of 24-isopropylcholestanes in the Neoproterozoic, but that the algal SMT duplication event occurred later in the Phanerozoic. Subsequently, pelagophyte algae and their relatives are an unlikely alternative to sponges as a source of Neoproterozoic 24-isopropylcholestanes, consistent with growing evidence that sponges evolved long before the Cambrian explosion ∼542 million y ago.sponges | Porifera | sterols | steranes | Amorphea

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Section: Stramenopiles IImentioning

confidence: 77%

Section: Stramenopiles IImentioning

confidence: 77%

Sterol and genomic analyses validate the sponge biomarker hypothesis

Gold

Grabenstatter

Mendoza

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

119

121

View full text Add to dashboard Cite

show abstract

“…For instance, compelling data has been put forward to suggest that C3o sedimentary 24-n-propylcholestanes are molecular fossils characteristic of marine algal input (Moldowan ~, 1990). This discovery presents an important tool for distinguishing marine and lacustrine sediments in the geologic record, based simply on the presence of these compounds.…”

Section: Implications Of Stenolloss For Biomarker Applicationsmentioning

confidence: 99%

Sedimentary lipids as indicators of depositional conditions in the coastal Peruvian upwelling regime

McCaffrey¹

1990

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“…; Fig. 8), suggesting a marine algal contribution (Moldowan et al 1990). Cheilanthanes are relatively abundant (23T-26T, Fig.…”

Section: Timementioning

confidence: 99%

Cretaceous carbonaceous rocks from the Norfolk Ridge system, Southwest Pacific: Implications for regional petroleum potential

Herzer

Sykes

Killops

et al. 1999

New Zealand Journal of Geology and Geophysics

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Late Cretaceous carbonaceous rocks have been dredged from two sites on the Norfolk Ridge system northwest of New Zealand. On the West Norfolk Ridge, Raukumara Series (late Cenomanian to late Coniacian, 95-86.5 Ma) coal measure sandstones and mudstones contain dispersed, immature (R O 0.37%), terrestrial (type III) organic matter and have poor petroleum generative potential (TOC 2.2-2.8%, S2 1.2-1.6 mg HC/g rock). However, the in situ coal measure sequence may contain abundant coal seams with excellent generative potential, and thus constitutes a potential source rock formation for the adjacent New Caledonia and Reinga Basins that have thick sections of sediments. The coal measures probably formed in a coastal plain environment subjected to episodic marine incursions. At the second dredge site, near the junction of the Norfolk and Reinga Ridges, a late Piripauan to early Haumurian (Santonian-Campanian, 85-75 Ma) marine shale contains sparse, mixed marine and terrestrial (type II/III) organic matter. Hopane and sterane parameters imply a maturity equivalent to at least 0.6% R o , but the analysed shale has poor generative potential (TOC 0.9%, S2 1.4 mg HC/g rock).Biomarkers suggest that the terrestrial contribution to bitumen in the shale is minor compared with the marine, but kinetic parameters are more consistent with a type III G97050

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Sedimentary 12- n -Propylcholestanes, Molecular Fossils Diagnostic of Marine Algae

Cited by 281 publications

References 24 publications

Sterol and genomic analyses validate the sponge biomarker hypothesis

Sterol and genomic analyses validate the sponge biomarker hypothesis

Sedimentary lipids as indicators of depositional conditions in the coastal Peruvian upwelling regime

Cretaceous carbonaceous rocks from the Norfolk Ridge system, Southwest Pacific: Implications for regional petroleum potential

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