Independent components analysis of starch deficient pgm mutants

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Independent components analysis of starch deficient pgm mutants. GCB 2004 M. Scholz, Y. Gibon, M. Stitt, J. Selbig. Overview. Introduction Methods PCA – Principal Component Analysis ICA – Independent Component Analysis Kurtosis Results Summary. Introduction – techniques. - PowerPoint PPT Presentation

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Matthias Maneck - Journal Club WS 04/05

Independent components analysis of starch deficient pgm mutants

GCB 2004

M. Scholz, Y. Gibon, M. Stitt, J. Selbig

Matthias Maneck - Journal Club WS 04/05

Overview

Introduction Methods

PCA – Principal Component Analysis ICA – Independent Component AnalysisKurtosis

Results Summary

Matthias Maneck - Journal Club WS 04/05

Introduction – techniques

visualization techniques supervised

biological background informationunsupervised

present major global information General questions about the underlying data

structure. Detect relevant components independent from

background knowledge.

Matthias Maneck - Journal Club WS 04/05

Introduction – techniques

PCAdimensionality reductionextracts relevant information related to the

highest variance ICA

Optimizes independence conditionComponents represent different non-

overlapping information

Matthias Maneck - Journal Club WS 04/05

Introduction - experiments

Micro plate assays of enzymes form Arabidopsis thaliana. pgm mutant vs. wild type continuous night

data j Samples

i Enz

ymes

Matthias Maneck - Journal Club WS 04/05

Introduction – workflow

j Samples

i Enz

ymes

j Samples

PC

’s

1st IC

2nd IC

j SamplesIC

s

PCA ICA KurtosisData ICs

Matthias Maneck - Journal Club WS 04/05

PCA – principal component analysis

-4 -3 -2 -1 0 1 2 3 4-4

-3

-2

-1

0

1

2

3

4

Enzyme 1

Enz

yme

2

Matthias Maneck - Journal Club WS 04/05

-4 -3 -2 -1 0 1 2 3 4-4

-3

-2

-1

0

1

2

3

4

Enzyme 1

Enz

yme

2

PCA – principal component analysis

2. Principal Component

1. Principal Component

Matthias Maneck - Journal Club WS 04/05

PCA – principal component analysis

-4 -3 -2 -1 0 1 2 3 4-4

-3

-2

-1

0

1

2

3

4

1. PC

2. P

C

Matthias Maneck - Journal Club WS 04/05

PCA – calculation

j Samples

i Enz

ymes

i Enz

ymes

i Enzymes

Eigenvectors

x1 ... ... xi

- mean

- mean

- mean

- mean

Data-Matrix Cov-Matrix

Eigenvalues

λ1

λi

Matthias Maneck - Journal Club WS 04/05

PCA – dimensionality reductionP

Cs

i Enzymes

j Samples

i Enz

ymes

j Samples

PC

s

=

Reduced Data MatrixData MatrixSelected Components

Matthias Maneck - Journal Club WS 04/05

-4 -3 -2 -1 0 1 2 3 4-4

-3

-2

-1

0

1

2

3

4

Enzyme 1

Enz

yme

2

PCA – principal component analysis

1. Principal Component

2. Principal Component

Matthias Maneck - Journal Club WS 04/05

PCA – principal component analysis

-4 -3 -2 -1 0 1 2 3 4-4

-3

-2

-1

0

1

2

3

4

1. PC

Matthias Maneck - Journal Club WS 04/05

PCA – principal component analysis

Minimizes correlation between components. Components are orthogonal to each other. Delivers transformation matrix, that gives the influence of

the enzymes on the principal components. PCs ordered by size of eigenvalues of cov-matrix

PC

s

i Enzymes

j Samples

i Enz

ymes

j Samples

PC

s

=

Reduced Data Matrix Data MatrixSelected Components

Matthias Maneck - Journal Club WS 04/05

ICA – independent component analysis

Person 1

Person 3

Person 2

Mike 1

Mike 3

Mike 2

microphone signals are mixed speech signals

)()()()(

)()()()(

)()()()(

3332321313

3232221212

3132121111

tsatsatsatx

tsatsatsatx

tsatsatsatx

Matthias Maneck - Journal Club WS 04/05

ICA – independent component analysism

icro

phon

esi

gnal

s

time tmixingspeech

mic

roph

one

time t

spee

chsi

gnal

s

=m

icro

phon

esi

gnal

s

time tdemixingspeech

spea

ker

time t

spee

chsi

gnal

s

=

Microphone Signals X Mixing Matrix A Speech Signals S

Microphone signals XDemixing matrix A-1 Speech signals S

Matthias Maneck - Journal Club WS 04/05

ICA – independent component analysis

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

5

10

15

20

25

30

35

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

5

10

15

20

25

30

35

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

5

10

15

20

25

30

35

0 0.5 1 1.5 2 2.5 30

10

20

30

40

50

60

The sum of distribution of the same time is more Gaussian.

Matthias Maneck - Journal Club WS 04/05

ICA – independent component analysis

Maximizes independence (non Gaussianity) between components.

ICA doesn’t work with purely Gaussian distributed data. Components are not orthogonal to each other. Delivers transformation matrix, that gives the influence of the PCs

on the independent components. ICs are unordered

j Samples

PC

s

j Samples

ICs

PCs

=

ICs Demixing Matrix Data Matrix

Matthias Maneck - Journal Club WS 04/05

Kurtosis – significant components

measure of non Gaussianity

z – random variable (IC) μ – mean σ – standard deviation

positive kurtosis super Gaussian

negative kurtosis sub Gaussian

3)1(

)()(

41

4

n

zzkurtosis

n

ii

Matthias Maneck - Journal Club WS 04/05

Kurtosis – significant components

Matthias Maneck - Journal Club WS 04/05

Influence Values

Which enzymes have most influence on ICs?

PC

si Enzymes

j Samples

i Enz

ymes

j Samples

PC

s

=

Reduced Data Matrix Data MatrixSelected Components

j Samples

PC

s

j Samples

ICs

PCs

=

ICs Demixing Matrix Data Matrix

Matthias Maneck - Journal Club WS 04/05

Influence Values

PC

s

i Enzymes

Selected Components

PCs

Demixing Matrix

i Enzymes

ICs

=

Influence Matrix

j Samples

i Enz

ymes

Data Matrix

i Enzymes

ICs

Influence Matrix

j Samples

ICs

ICs

=

Matthias Maneck - Journal Club WS 04/05

Results

pgm mutantcompares wild type and pgm mutant17 enzymes,125 samples

wild type, pgm mutant

continuous nightresponse to carbon starvation17 enzymes, 55 samples

+0, +2, +4, +8, +24, +48, +72, +148 h

Matthias Maneck - Journal Club WS 04/05

Results – pgm mutant

Matthias Maneck - Journal Club WS 04/05

Matthias Maneck - Journal Club WS 04/05

Results – continuous night

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Results – combined

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Results – combined

Matthias Maneck - Journal Club WS 04/05

Results – combined

Matthias Maneck - Journal Club WS 04/05

Summary

ICA in combination with PCA has higher discriminating power than only PCA.

Kurtosis is used for selection optimal PCA dimension and ordering of ICs.

pgm experiment, 1st IC discriminates between mutant and wild type.

Continuous night, 2nd IC represents time component.

The two most strongly implicated enzymes are identical.

Matthias Maneck - Journal Club WS 04/05

References

Scholz M., Gibon Y., Stitt M., Selbig J.: Independent components analysis of starch deficient pgm mutants.

Scholz M., Gatzek S., Sterling A., Fiehn O., Selbig J.: Metabolite fingerprinting: an ICA approach.

Blaschke, T., Wiskott, L.: CuBICA: Independent Component Analysis by Simultaneous Third- and Fourth-Order Cumulant Diagonalization. IEEE Transactions on Signal Processing, 52(5):1250-1256.http://itb.biologie.hu-berlin.de/~blaschke/

Hyvärinen A., Karhunen J., Oja E.: Independent Component Analysis. J. Wiley. 2001.

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