Action Spectrum of the "Second Emerson Effect".

Area of Science:

• Photosynthesis research
• Algal physiology
• Photobiology

Background:

• The
• second Emerson effect
• describes the enhancement of photosynthesis when two different wavelengths of light are used simultaneously.
• Understanding the specific pigments and their roles in this effect is crucial for optimizing photosynthetic efficiency.

Purpose of the Study:

• To investigate the action spectrum of the
• second Emerson effect
• in various algae species.
• To identify the specific pigment responsible for light absorption at 670 mmu and its contribution to the effect.

Main Methods:

• Analysis of action spectra for the
• second Emerson effect
• in Chlorella pyrenoidosa, Navicula minima, Anacystis nidulans, and Porphyridium cruentum.
• Spectroscopic analysis to identify pigment absorption bands.
• Investigating the influence of light intensity and wavelength on photosynthetic yield.

Main Results:

• A distinct peak at 670 mmu was observed in the action spectra of several algal species, attributed to a form of chlorophyll a (Chl a 670).
• Chl a 670 was found to enhance photosynthesis by far-red light as effectively as other known accessory pigments.
• In Anacystis nidulans, phycocyanin absorption peaks were identified at 570, 600, and 640 mmu, and light intensity relationships influenced the Emerson effect.

Conclusions:

• A previously unrecognized form of chlorophyll a, Chl a 670, plays a significant role in the
• second Emerson effect
• by absorbing light at 670 mmu.
• The findings contribute to a more comprehensive understanding of light harvesting and energy transfer in photosynthesis across different algal groups.