| Thus far we mostly looked at the core-lipid part (traditional biomarker) of a lipid. what is an IPL? | Intact polar lipid, forms main constituent of cell mebranes in most organsims. It is the whole molecule as it occurs in the cell with polar headgroup attached. Large sturctureal variety. they are labile compounds that degrade rapidly upan cell death (hours to days, but can be perserved better (geological time scales) in optimal and anoic conditoins). |
| IPLs are widely used as | biomarkers for living microbial cells |
| Traditionally analysed through | seperating dead biomass lipids from IPLS and then extracting core lipids from IPLs unde rlab conditions (taking off the polar headgroup) - losing information :( |
| alternative modern technique | Directly analyse the IPL using LC-MS (liquid chrom. mass spec) or ESI-MS (electrospray ionization mass spectrometry). No separation of the polar headgroup and core lipids – the LC-MS can analyse IPL and core lipids and you can differentiate from the two in the resulting MS. However, qunaitifcation is difficult. |
| When analysing organic matter with IPLs they are assumed to come from living biomass and can signify | a (recent) turnover inmicrobial community compared to the dead biomass core lipids |
| IPL counts should be highest where .... is highest | chlorophyll - biomass is highest, bloom max |
| - Algae and/or bacteria can synthesize non-phospholipids to accommodate ... | phosphor limitation (no phosphor in headgroup) |
| If you synthesise sulphur over phosphor, you are competitive when nutrients are ... Who does this? | low - cyanobacteria |
| Microbes may switch to sulphur, nitrogen, or sugar lipids at ... | P-limitation |
| ladderane lipids (staircase structure) ar biomarkers for ... | anammox (anaerobic ammonium oxidation) |
| If you wan tto know where anammox is active and not where it WAS active you have to analyse ladderane IPLs, here the laderanne is found in the ... | ladderane as the tail/corelipid |
| We can correlate DNA and IPL abbundances because .. | they are both representative of the current environement. Turnover rate is too fast for corelipid (fossil) vs DNA |
| Heterocyst glycolipids are biomarkers for | heterocyst cyanobacteria and N-2 fixation (they look a bit like IPLs) |
| C5 glycolipids occur in | lake and soil environemnt, fresh water system |
| C6 glycolipids occur in | salty (open)marine environments |
| Why is the headgroup of glycolipids still intact in ancient sediments? | Sugar is slightly stronger attached to the long chain – ether bond in glycolipid (degrades slow) vs. ester bond in IPL (degrades fast) |
| IPLs are great, but don’t work with glycosidic ether lipids as they degrade very slowly - give a reason why | they dont represent the modern environement anymore, but could also signify an older commmunity |
| Untargeted analysis (‘lipidomics’) reveals enormous diversity in intact polar lipids in the environment, but | it is a very complex and large set of data |
| Global ocean lipidomes show a universal relationship between temperature and lipid unsaturation, where ... | increasing temperatures = fewer double bonds -> saturation increases with temperature |
| Because unsaturation decreases with climate change this will result in | Less omega fatty acids, influencing diets |
| Head group diversity is large and phospholipids are not really dominant in the different environments | aparently we just need to know this so read it hahah |
