Kathrin JanssenUniversity of Bonn | Uni Bonn · Institute of Medical Microbiology, Immunology and Parasitology
Kathrin Janssen
Dr. rer. nat.
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11
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Publications
Publications (11)
Bacteria play an important role in the fossilization of soft tissues; their metabolic activities drive the destruction of the tissues and also strongly influence mineralization. Some environmental conditions, such as anoxia, cold temperatures, and high salinity, are considered widely to promote fossilization by modulating bacterial activity. Howeve...
Premise:
Within a broader study on leaf fossilization in freshwater environments, a long-term study on the development and microbiome composition of biofilms on the foliage of aquatic plants has been initiated to understand how microbes and biofilms contribute to leaf decay and preservation. Here, water lily leaves are employed as a study model to...
Past claims have been made for fossil DNA recovery from various organisms (bacteria, plants, insects and mammals, including humans) dating back in time from thousands to several million years BP. However, many of these recoveries, especially those described from million-year-old amber (fossil resin), have faced criticism as being the result of mode...
Phosphatized fish fossils occur in various locations worldwide. Although these fossils have been intensively studied over the past decades they remain a matter of ongoing research. The mechanism of the permineralization reaction itself remains still debated in the community. The mineralization in apatite of a whole fish requires a substantial amoun...
Fossilization processes and especially the role of bacterial activity during the preservation of organic material has not yet been well understood. Here, we report the results of controlled taphonomic experiments with crayfish in freshwater and sediment. 16S rRNA amplicon analyzes showed that the development of the bacterial community composition o...
Lantibiotics are post‐translationally modified antibiotic peptides with lanthionine thioether bridges that represent potential alternatives to conventional antibiotics. The lantibiotic pseudomycoicidin is produced by Bacillus pseudomycoides DSM 12442 and is effective against many Gram‐positive bacteria, including methicillin‐resistant Staphylococcu...
The preservation of soft tissue in the fossil record is mostly due to the replacement of organic structures by minerals (e.g. calcite, aragonite or apatite) called pseudomorphs. In rare cases soft tissues were preserved by pyrite. We assume that adipocere, as the shaping component, might be a preliminary stage in the pyritisation of soft tissues un...
The fossilization of soft tissues is generally the replacement of organic structures
by pseudomorphs in which muscle tissue is mostly replaced by minerals (i.e., phosphate,
carbonate or pyrite). Micro-CT observations of decomposing crayfish in tank
and distilled water, show a precipitation of crystal clusters over time. In addition, a mineralized
m...
Experiments are reported to reconstruct the taphonomic pathways of fish toward fossilisation. Acrylic glass autoclaves were designed that allow experiments to be carried out at elevated pressure up to 11 bar, corresponding to water depths of 110 m. Parameters controlled or monitored during decay reactions are pressure, salinity, proton activities (...
The aim of this study was to test the identification of methicillin resistance in coagulase-negative staphylococci by routine matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). SCCmec cassettes of type II, III and VIII encode a small peptide called PSM-mec in the vicinity of mecA. It is visible at m/z 2415...
Questions
Questions (2)
Hey all,
I am working with soft tissue decay experiments under different abiotic conditions. One parameter is the temperature, that is shifted to 4 °C. Under 24 °C we saw calcite precipitation and under 4 °C not which is obvious because calcite precipitation is an endothermic reaction. I just wonder why there is also calcite precipitation in arctic lakes or why molluscs e.g. are able to form their calciumcarbonate shelvs in cold water?
Has anyone of you literature recommendations where this topic is discussed? Or where other parameter enabling calcite precipitation at that temperature are named?
That would be quite interesting and you would help me a lot :)
Best,
Kathrin
Hey all,
we are doing microbiome analysis with soft tissue of crayfish. We perform all our experiments in biological triplicates, means that we have three crayfish per timepoint.
We extract the DNA from the soft tissue and send the extracted DNA to a sequencing facility that sequence each of the replicates individually. We get the raw data, analyse them via QIIME2 and after the taxonomic classification, I proceed working with R.
So, my question is, how would you work with these replicates, analyse the replicates, respectively?
Do you take the mean of the counts, e.g. when you analyse the microbial community in the samples? In that case, do you also look at the stdev? And how? Sometimes the replicates are very different. Do you have any recommendation on programs that analyse the stdev of the replicates? Or tell me if the replicates are comparable?
Or do you take each replicate alone? Another possibility would be to take only one of the replicates for the analysis? But how do you decide which one?
You would help me a lot,
Kathrin
