Diatom microfossils from cretaceous and eocene sediments contain native silica precipitating long‐chain polyamines

Abstract

Organic molecules from known biological sources (biomarkers) that are preserved over geological time are critical tools in the study of past conditions and events on earth. Polar molecules are typically recycled rapidly in marine environments and do not survive burial within aquatic sediments in unambiguously recognizable form. As such, geological biomarkers are formed almost exclusively from precursor biomolecules that have been altered, limiting their utility as paleoproxies. Here, we report that nitrogen-rich aliphatic long-chain polyamines (LCPAs), biosynthesized by diatoms in species-specific assemblages for the precipitation of nanopatterned siliceous cell walls (frustules), are preserved unaltered in the oldest available diatom fossils dating to the Lower Cretaceous (early Albian, 115-110 Ma). We further show that the cumulative LCPA pool accounts for 60% of the total C and 80% of the total N preserved in the Cretaceous age sediments. We suggest that silica glass formation by diatoms constitutes an important preservation mechanism for source-specific, polar biomolecules, protecting them indefinitely by encapsulation within the silicified frustule. LCPAs are a unique, source-specific carbon and nitrogen archive of diatom biomass, offering a promising tool for reconstruction of global cycles of carbon and nitrogen over geological timescales.

Capabilities and limitations of direct analysis in real time orbitrap mass spectrometry and tandem mass spectrometry for the analysis of synthetic and natural polymers

“…Natural polyamines consist of polypropyleneimine structures with variable degrees of methylation and chain length. In this study, we used two standard mixtures of aliphatic non‐methylated (PPI) and methylated (N‐methyl PPI) polypropylamines that are similar to the polyamine structural moieties identified in various diatom and sponge species . The PPI standard mixture consisted of a series of 14 linear polypropyleneimine compounds varying in the number of propylamine repeat units (n = 5–11) and in the presence or absence of a terminal methyl group (R = ‐H, ‐CH3; Scheme ) .…”

Unusual Polyamines from Baikalian Diatoms

“…Recently, LCPAs have been found in marine sediments;, that contain a large quantity of siliceous diatom frustules. The study of polyamines from the Baikal sediments (Figure and Figure , Table ) shows the presence of three kinds of LCPAs described above, including propylamine‐ and butylamine‐based substances.…”

“…There are two kinds of these polyamines; they differ according to the structure of their first unit ( Table 4S in Thus, the polyamines from U. ferefusiformis consist of substances of various degrees of methylation, and because these polyamines have a first unit with two different structures, the mass spectrum is more complicated than that of S. meyeri. Recently, LCPAs have been found in marine sediments; [29,30] that contain a large quantity of siliceous diatom frustules. The study of polyamines from the Baikal sediments ( Figure 8 and Figure 9, Table 1) shows the presence of three kinds of LCPAs described above, including propylamine-and butylaminebased substances.…”

Survival of fossils under extreme shocks induced by hypervelocity impacts

“…As well as being extant today, diatoms have been identified in the fossil record back to the Lower Cretaceous (approx. 140–100 Ma), and their use has been posited as a significant tool in providing records of conditions at their time of formation [22]. …”