3. Metabolomics: www.scopus.com statistics
( TITLE-ABS-KEY ( aquatic AND ecology ) ) 13200 documents
( TITLE-ABS-KEY ( aquatic AND ecology ) ) AND ( metabolomics ) 76 documents
23 reviews
4. Metabolomics: definitions
What can the cell potentially do?
What is currently being turned on?
What enzymes are currently active?
What is being produced/consumed?
System biology
5. Metabolomics: definitions
metabolomics is the "systematic study of the unique chemical fingerprints that
specific cellular processes leave behind", the study of their small-molecule
metabolite profiles (Daviss 2005)
metabolomics is a newly emerging field of "omics" research concerned with the
comprehensive characterization of the small molecule metabolites in biological
systems. (Metabolomics Society)
metabolomics is the comprehensive and holistic study of the metabolome
the complete set of small-molecule
metabolites to be found within a biological
sample
metabonome: the complete set of metabologically
regulated elements in cells
6. Metabolomics: definitions
Organic compounds of small molecular weight (less than 2000 Dalton)
Sugars, amino acids, ammines, vitamins, lipids, organic acids, phenolic acids, flavonoids, stilbenes, sugar-
alcohols, carotenoids, terpenoids, hydrocarbons, etc
polymeric: saccharides, lignin, peptides, tannins, DNA, proteins, etc
metabolomics aims to measure ALL metabolites with ONE analysis
In metabolomics by definition the metabolites of interest (analytes)
are NOT pre-defined
Please DON’T use the term
‘targeted metabolomics’
(use the term: ‘analysis of metabolites’)
11. Targeted versus Untargeted
Prefer targeted methods when:
You focus in a targeted group or single metabolite (you know what to measure)
You want/need the absolute concentration (except NMR)
You don’t know very good your instrument (analytical chemistry skills)
You are not familiar with compound annotation
You have a poor knowledge of your sample metabolome
You don’t have plenty of time for data analysis / you want fast results
You want to work alone (biology, organic chemistry, biochemistry, analytical chemistry,
bioinformatics, chemo-metrics)
13. Metabolomics: from where metabolites are coming from
What can the cell potentially do?
What is currently being turned on?
What enzymes are currently active?
What is being produced/consumed?
System biology
Are all metabolites product of biochemical process?
15. Metabolomic: what is and what is not
How big is the metabolome?
Sigma-Aldrich has ~55K commercial available chemicals
Kegg contains 18K metabolites
HMDB is based in ~42K metabolites
Plant metabolome is estimated to cover 200K metabolites
PubChem ID contains more than 10M entries
CAS contains over 90M unique organic
and inorganic chemicals
ChemSpider contains over 57M
compounds from 530 data sources
2017
16. Plant metabolome is estimated to cover
200 000 metabolites
#ofmetabolites5-21% ethanol
g/L
mg/L
µg/L
ng/L
pg/L
fg/L
Metabolomics: what is and what is not
How big is the metabolome?
18. Lisec et al. Anal Chem 2016
Currently, the best dynamic range of modern MS is 106
approximately and is significantly lower than the estimated
concentration range of cellular metabolites as 1012 or more (Lei
et al JBC 2011)
Metabolomics: problems
19. Metabolomics: facts
Holistic approach: complementary platforms
Multidisciplinary: chemistry + biology + physics + mathematics + informatics
Untargeted: the metabolites are by definition not pre-defined
Unfeasible validation: hundreds to thousands metabolites, many unknown
Self-awareness: minimum reporting standard / levels of annotation
Mass Spectrometry (MS)
Direct infusion/Imaging
Gas Chromatography (GC)
Liquid Chromatography (LC)
Capillary Electrophoresis (EC)
Nuclear Magnetic Resonance (NMR) NMR: up to 100 metabolites
few hundreds metabolites
ESI-
ESI+
Reverse Phase (RP)
Normal Phase (NP)
few hundreds metabolites
few thousands metabolites
GCxGC
few hundreds metabolites
Derivatisation
No method can cover all metabolites
Each method has advantages and disadvantages
Certain overlap between the different methods exists
21. Metabolomics: no separation (extraction-solubility)
Cyclohexane
Petroleum ether
Hexane
Diethyl ether
Chloroform
Ethanol
Acetone
Methanol
Water
least polar
most polar
37. Metabolomics: facts
Holistic approach: complementary platforms
Multidisciplinary: chemistry + biology + physics + mathematics + informatics
Untargeted: the metabolites are by definition not pre-defined
Unfeasible validation: hundreds to thousands metabolites, many unknown
Self-awareness: minimum reporting standard / levels of annotation
Mass Spectrometry (MS)
Direct infusion/Imaging
Gas Chromatography (GC)
Liquid Chromatography (LC)
Capillary Electrophoresis (EC)
Nuclear Magnetic Resonance (NMR) NMR: up to 100 metabolites
few hundreds metabolites
ESI-
ESI+
Reverse Phase (RP)
Normal Phase (NP)
few hundreds metabolites
few thousands metabolites
GCxGC
few hundreds metabolites
Derivatisation
No method can cover all metabolites
Each method has advantages and disadvantages
Certain overlap between the different methods exists
48. Experimental
design
Experiment
Sampling
LC-MS
analysis
Data
processing
XCMS
QC
Metabolomics: dry lab – data processing
Markers
detection
Markers
validation
Markers
identification
Hypothesis
generation
Tip #4: QC samples are your best friend*
Tip #5: Understand/Know your instrument/method**
Tip #6: Blacks and Standard mixes are not good QC sample
Tip #7: Think if you really need IS(s)
*show my your friend and I will show you your future
**velocity, coverage, resolution, accuracy, robustness during the time of analysis
machines are limited