Distribution of selenium and arsenic in differentiated multicellular eukaryotic fossils and their significance
-
Abstract
We present variation patterns of trace elements within different sequences of the Ediacaran Doushantuo Formation
(DST, 635–551 million years ago), and inside the cells of the earliest differentiated multicellular
eukaryotic fossils of the Weng’an biota in the Weng’an County of Guizhou Province. The results showed that
selenium is the most enriched and significantly varied trace element among the 22 trace elements throughout the
DST, followed by arsenic. The highest selenium and arsenic content sequences are consistent with the first
appeared sequence of the earliest differentiated multicellular eukaryotic fossils Megasphaera at the middle to
upper parts of the DST. Nanoman secondary ion mass spectrometry analyses show that selenium and arsenic have
an inhomogeneous and punctate distribution in the nucleus and cytoplasm. The nucleus has anomalously enriched
levels of selenium and arsenic among the organelles. The selenium and arsenic concentrations exhibit a positive
correlation with the diversity of fossilized Megasphaera. These new findings give us a clue that the anomalous
enrichment of selenium and arsenic might contributes to the cell differentiation in Ediacaran Doushantuo period.
-
-