Research Worshop 2 : Chromatic Acclimation in Marine Cyanobacteria - - PowerPoint PPT Presentation

Master 2ème année : Sciences et Technologies Mention : Sciences de l’Univers, Environnement, Ecologie Spécialité : Océanographie et Environnement Marin

UE Evolution of marine Phytoplankton & Biogeochemistry

Research Worshop 2 : Chromatic Acclimation in Marine Cyanobacteria

Christophe Six

UMR UPMC-CNRS 7144 “Procaryotes Photosynthétiques Marins" Station Biologique de Roscoff Université Pierre et Marie Curie (Paris VI). Bureau 354, 3ème étage (Batiment GT) six@sb-roscoff.fr

Research workshop 2

. Bringing out a scientific question from a scientific context . Setting up a experiment plan . Carring out the experiments . Synthetising and presenting the results . Interpreting the results . Communicating the results and their interpretation properly

. Learning and understanding the scientific approach . Personal work : a short report in the form of a research article

• Introduction, Methods, Results, Discussion

Article due by February 1st on pdf Format at six@sb-roscoff.fr

. Methods : culturing phytoplankton, flow cytometry and biophysics of photosynthesis . Results and interpretation : together

0.01

Chl (mg/m3)

1

60

0.01

Chl (mg/m3)

1

60

However Synechococcus cells are detected everywhere !

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Pigment type 1 Pigment type 2 Pigment type 3a Pigment type 3b Pigment type 3c

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Wavelength (nm)

400 450 500 550 600 650 700 750

Relative absorbance (AU)

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

Col 8 vs Col 9 Col 8 vs Col 11 Col 8 vs Col 13 Col 8 vs Col 15 Col 8 vs Col 17 Type 1 (WH5701) Type 2 (WH8018) Type 3a (WH7803) Type 3b (RCC307) Type 3c (WH8102)

Pigment type 1 Pigment type 2 Pigment type 3a Pigment type 3b Pigment type 3c

What is chromatic acclimation ?

Chromatic acclimation is a physiological process that allows photosynthetic

• rganisms, in particular cyanobacteria, to modulate their pigmentation in

function of the environmental variations of spectral light quality

. Freshwater cyanobacteria :

• Publication by Nicole Tandeau de Marsac in 1977
• Between green light and red light
• Between green light and red light
• Variations of the ratio of phycobiliproteins : phycocyanin versus phycoerythrin
• A lot of knowledge on this process

Fremyella diplosiphon

What is chromatic acclimation ?

Chromatic acclimation is a physiological process that allows photosynthetic

• rganisms, in particular cyanobacteria, to modulate their pigmentation in

function of the environmental variations of spectral light quality

. Marine cyanobacteria : Synechococcus spp.

• Recent discover : Brian Palenik in 2001
• Between blue light and green light
• Variable ratio of phycobilins
• Very little is known on this acclimation process

Synechococcus sp.

Research Worshop 2

Photophysiology of marine picocyanobacteria : Chromatic acclimation among marine Synechococcus spp.

Variations of the optical characteristics of light in seawater

Do all Synechococcus chromatic adapters carry out the same process ? Physiological diversity ? Raising hypotheses : How do they do ? Influence of other physical factors ?

• Does it influence cell growth (primary productivity) and how ?

Comparison of 3 Synechococcus strains that chromatically acclimate:

• Synechococcus sp. RCC2531 (M11.1)
• Synechococcus sp. RCC2570 (MICROVIR 16CH_1)
• Synechococcus sp. RCC515 (BL_107)

Research Worshop 2

Photophysiology of marine picocyanobacteria : Chromatic acclimation among marine Synechococcus spp. Experimental protocole : Monitoring cultures of these three strains upon a shift

• f the spectral quality of light

Blue Light

• Green Light

Green Light

• Blue Light
• Influence on growth
• kinetics and specificities of acclimation

Culture monitoring

Research Worshop 2

Photophysiology of marine picocyanobacteria : Chromatic acclimation among marine Synechococcus spp.

Every morning, for 10 days

• Monitoring the variations of cell density : flow cytometry
• Monitoring the phycobiliprotein fluorescence properties : spectrofluorimetry
• Monitoring the variations of global optical properties : flow cytometry