Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2008 Dec 9;105(49):19360-5. doi: 10.1073/pnas.0810106105. Epub 2008 Dec 1.

Embryo fossilization is a biological process mediated by microbial biofilms.

Author information

1
Department of Biology and Indiana Molecular Biology Institute, Indiana University, Bloomington, IN 47405, USA. raff@indiana.edu

Abstract

Fossilized embryos with extraordinary cellular preservation appear in the Late Neoproterozoic and Cambrian, coincident with the appearance of animal body fossils. It has been hypothesized that microbial processes are responsible for preservation and mineralization of organic tissues. However, the actions of microbes in preservation of embryos have not been demonstrated experimentally. Here, we show that bacterial biofilms assemble rapidly in dead marine embryos and form remarkable pseudomorphs in which the bacterial biofilm replaces and exquisitely models details of cellular organization and structure. The experimental model was the decay of cleavage stage embryos similar in size and morphology to fossil embryos. The data show that embryo preservation takes place in 3 distinct steps: (i) blockage of autolysis by reducing or anaerobic conditions, (ii) rapid formation of microbial biofilms that consume the embryo but form a replica that retains cell organization and morphology, and (iii) bacterially catalyzed mineralization. Major bacterial taxa in embryo decay biofilms were identified by using 16S rDNA sequencing. Decay processes were similar in different taphonomic conditions, but the composition of bacterial populations depended on specific conditions. Experimental taphonomy generates preservation states similar to those in fossil embryos. The data show how fossilization of soft tissues in sediments can be mediated by bacterial replacement and mineralization, providing a foundation for experimentally creating biofilms from defined microbial species to model fossilization as a biological process.

PMID:
19047625
PMCID:
PMC2614766
DOI:
10.1073/pnas.0810106105
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center