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Lecture 4


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[Front]


What are pieces of information content found in biomarkers and are species specific?
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carbon skeleton, type and positions of functional groups, stereochemistry and isotope content (13C, 14C, 2H, 15N, 34S, etc.)

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What are pieces of information content found in biomarkers and are species specific?
Carbon skeleton, type and positions of functional groups, stereochemistry and isotope content (13C, 14C, 2H, 15N, 34S, etc.)
Species-specific biosynthesis relys on the principle that:
Same amount of C’s and H’s but different structure, functional groups or d13C  can tell us about the species specific biosynthesis/pathway of synthesizing the lipid/environment
Diagenesis and catagenesis ...
Increase loss of information during the increasing burial and time
Over time the carbon skeleton may survive,, but the functional groups may get lost, this causes ...
It to become more difficult to recognize the original biomarker and thus the source organism
Over time dinosterol may turn into... (dia/catagenesis)
Dinosterene (loss of OH, substituted by double bond) and dinosterane (loss of double bonds, replaced by H's?)
What kind of organisms make dinosterol?
Eukaryotes (sterol! 3 cyclohexane, 1 cyclopentane) - specifically dinoflagellates
Prokaryotes
Are organisms whose cells lack a nucleus and other organelles. Prokaryotes are divided into two distinct groups: the bacteria and the archaea. Most prokaryotes are small, single-celled organisms that have a relatively simple structure.
Eukaryotes
Are organisms whose cells contain a nucleus and other membrane-bound organelles. There is a wide range of eukaryotic organisms, including all animals, plants, fungi, and protists, as well as most algae. Eukaryotes may be either single-celled or multicellular.
Ribosomes
The cell’s protein-synthesising factories, are composed of structural RNA and various proteins. Ribosomes are present in ALL cells and the sequence of the gene encoding for 16S or 18S ribosomal RNA is used for molecular phylogeny of all organisms.
Chlorophyll a = present in almost all phytoplankton species, a good biomarker for this is ?
Phytol (acyclic diterpene alcohol) is a good biomarker for algae! Due to diagenesis this may turn into phytane (no OH group) -> diterpene alcohol
IPL are the basic building blocks of cell membranes. They contain at least one .... headgroup. They are very good biomarkers because ?
Hydrophilic - Large structural variety in the fatty acid tails, types of bonds and also in the headgroups
Why are sterols not the best biomarkers?
They are not really exclusive to certain groups
Who make these
Occurs specifically in Chrysophyte algae (‘brown algae’)
Who make these
Occurs in Porifera (“sponges”) (but also a bit in Chrysophytes, brown algae)
Who makes this 27-nor?
Kareniadinoflagellate algae (but also occur in other dinoflagellates as minor compounds)
Occurrence of highly branched isoprenoid (HBI) alkenes are produced by...?
A small number of marine diatoms (C25 and C30, with some double bonds)(specific genera: Rhizosolenia, Haslea, Pleurosigma, Navicula)
IP25 is a .... biomarker for ....
Highly branched isoprenoid (HBI) specific to arctic sea ice diatoms (seasonal! not permanent cover, need light!)
IPSO25 is a ... biomarker for ... . And what does its name stand for?
Highly branched isoprenoid (HBI) is specific for melting antarctic ice & Ice Proxy for the Southern Ocean with 25 carbon atoms
Who makes these b-amyrins/tetra-aromatic triterpanes
Angiosperms (enclosed seed/flowering plants)
Who is making the oleanane biomarker (triterpenoid) and what do they originate from
Diagnostic biomarker of angiosperms- tetra-aromatic triterpanes /b-amyrin but lost double bonds
What is this and who made it?
Sterane (see sterol structure) - eukaryotes
What is this and who made it?
Tetrahymanol (cyclic triterpenoid + alcohol group) - bactivirous ciliates
What is this and who made it?
Oleanane (cyclic triterpenoid) - angiosperms
What is this and who made it ?
Taraxerol - mangroves (cyclic triterpenoid, alcohol group (-ol), 1 double bond)
Levoglucose traces ..
Terrestrial biomass burning
Who make sterols in their membrane lipids?
Eukaryotes (sterol = 3-cyclohexane, 1-cyclopentane & OH-group)
What types of lipids & bonds are specific to archaea ?
Isoprenoid ether lipids - so ether bonded
Some archaea form ... for their membranes instead of bilayers
Monolayers (2 polar heads with 1 polar tail in between)
Crenarchaeota are ... and make ...
Hyperthermophyles - cyclopentane rings in their monolayer lipids (tetraether GDGTs-n)
Euryarcheaota are for example .... and .... . How are their membranes structured?
Halophiles and methanogens . They have bilayers of archaeol or monolayers of GDGTs
How do we analyse tetraetherlipids?
Take off the head groups leaving the carbon skeleton and its rings to be analysed with GC-MS. LC-MS nowadays more suitable for larger molecules if soluble.
Ether bonds of archaea are very...
Strong and resitant to acids compared to ester bond
Thaumarchaeota are the ones making ...
Crenarchaeol - GDGT with 4 cyclopentanes and 1 cyclohexane
What is crenarchaeol a biomarker for?
Thaumarchaeota - ammonia oxidizing archaea (and so ammonia oxidation)
Ammonium oxidation by thaumarcheaota uses ... and releases ...
Ammonia (NH3) to nitrite (NO2 -) (increases when thaumarchaeota bloom)
Crenarcheol hate.. . And why does this matter?
Free sulphite, causes them not to occur that much anymore at great depth (2000m)
Crenarcheol don't show 13C depletion of methane because
They are in the nitrogen cycle not in methane cycle
Occurrence in archae of GDGTs.
Yeh no question, just loook at it for a second
Irregylar acyclic isoprenoids - characteristic for ? and because?
Methanogens & anaerobic oxidation of methane - depletion in 13C due to methane cycle - so archae involved in methane cycle
(Tetra- and di-) ether lipids also occur in bacteria but ...
With straight chain or branched chains and mostly no cyclopentanes
“branched” GDGTs are biomarkers for
Acidobacteria Likely Acidobacteria.
Isorenieratene is a characteristic pigment for ...
Photosynthetic anaerobic green sulphur bacteria - and biomarker for euxinia
Okenone is a characteristic pigment for
Photosynthetic anaerobic purple sulphur bacteria (anoxia high in photic zone!)
Iso- and anteiso fatty acids often in ...
Anaerobic bacteria /sulphate reducers
.... are biomarkers for bacteria but only a few are specific for classes of bacteria
Hopanoids (e.g. 3-methyl hopanoids in combination with 13C-depletion for methanotrophic bacteria)
Annamox process =
Ammionium + nitrite and releases nitrogen gas (harmless) - used to treating wastewaters! But slow and anoxic
Heterocyst glycolipids are biomarkers for
N2-fixing heterocyst cyanobacteria (blue algae), need oxygen!
What is heterocyst?
Special cell compartment, this is where N2 fixing takes place for N2 fixing cyanobacteria
Ladderane lipids (staircase structure) are biomarkers for ...
Anaerobic ammonium oxidizing "annamox" bacteria --> anoxia and ammonium oxidation
Are biomarkers specific for microbial groups or biosynthetic pathways?
Through biosynthetic pathways – these pathways can go extinct, and through these microbial groups as well
Why do “Early-branching” groups of thermophilic bacteria look to have “unusual” membrane lipids?
They look archaea like, producing non-isoprenoid ether lipids or a mix of ester and ether lipids and form membrane spanning monolayers.
Bacterial membrane lipids are always
Non-isoprenoid but rather straight or branched (archaea are isoprenoid)
Bacterial branched GDGT are found in
Peats and soils, not much in marine
Branched GDGTs are abundant in
Anoxic parts of peat bogs -> anaerobic bacteria (preservation bias?) - made by acidobacteria (peats are acidic - making is diabolic acid)
Hopanoids, in contrast to steroids, are not restricted to ... .
Aerobic bacteria, but can also be found in anaerobic bacteria (anammox, iron-reducing, sulfate reducing, etc.)
Bacteriohopanepolyol - what is the functional role of hopanoids
Mainly bacterial membrane rigidifiers, but also not completely sure what their unique property is. Polar side chain 9blue) is most unique and indicative part. But also greatd iversity in ringsystem methylations