Nav: Home

Photosynthesis in the dark? Unraveling the mystery of algae evolution

April 24, 2017

Tokyo, Japan - Scientists have long studied which of the three primary photosynthetic eukaryotes (red algae, green algae, and glaucophytes) has come into existence first to unravel the biological mystery of algae evolution by analyzing their genetic information.

Despite learning that the structure of cyanelles, an organelle unique to glaucophytes, is most similar to the ancestral cyanobacteria among other organelles, these studies have not conclusively resolved the branching position of glaucophytes and left the early branching history of the three primary photosynthetic lineages uncertain.

A recent study by Waseda University researchers indicated that the effect of respiration on photosynthesis in the glaucophyte Cyanophora paradoxa is surprisingly similar to the interaction between respiration and photosynthesis in cyanobacteria. These results suggest that cyanelles retain many of the characteristics observed in their ancestral cyanobacteria.

"From the view point of metabolic interactions, C. paradoxa is the primary symbiotic algae most similar to cyanobacteria," says Kintake Sonoike, a professor of plant and cell physiology at Waseda University. "Our findings provide valuable information for revealing how photosynthetic organisms evolved."

This research is published in Scientific Reports.

The evolution of photosynthetic organisms began approximately 2.5 billion years ago when cyanobacteria came into existence and first used water molecules for photosynthesis, releasing oxygen as a by-product and changing life forms on earth. After an endosymbiosis event involving a eukaryote and a cyanobacterium, red algae, green algae and glaucophytes diverged from its common ancestor, a eukaryotic photosynthetic organism. In this long process, various metabolic interactions in cells have changed dramatically. For example, when cyanobacteria, which had performed both photosynthesis and respiration until then, evolved into chloroplast, mitochondria became responsible for respiration. Yet, there was a lack of information of these aspects in glaucophytes which needed to be addressed in order to understand the diversity of photosynthetic regulation and metabolic interaction among primary symbiotic algae.

In this study, Professor Sonoike measured chlorophyll fluorescence using a pulse-amplitude modulation (PAM) fluorometer to analyze photosynthesis in C. paradoxa, without destroying the cells, and check its interactions with metabolic reactions such as respiration. The application of such technique to algae is not easy, but being an expert in measuring fluorescence in cyanobacteria, Professor Sonoike successfully adapted the method to this research.

Fluorescence emission of chlorophyll was measured by shining different kinds of light on glaucophyte cells. As a result, the levels of nonchemical quenching (NPQ), a mechanism of algae to protect themselves from intense light, was high in the dark but decreased under low light, and increased again under high light. This implies that photosynthesis of glaucophytes is affected and changed by other metabolic reactions, even in the dark.

"Such concave light dependence was quite similar that observed in cyanobacteria," points out Professor Sonoike. "Although glaucophytes perform photosynthesis and respiration separately with respective organelles unlike cyanobacteria, similar metabolic interactions are observed in both organisms."

These results formulate a new theory on the effects of respiration and other metabolic reactions on photosynthesis. Such metabolic reactions are believed to slow down photosynthetic efficiency, but glaucophytes seem to use a different metabolic pathway to make up for the loss. In recent years, it was found that though plants without DNA regulation on photosynthesis can survive under certain light conditions, such plants can be easily destroyed in nature, where the amount of light depends on the environment. Taking this into consideration, a hypothesis arises that regulating photosynthesis in dark places under weak light through metabolic interactions in advance may be necessary for effective photosynthesis in nature. Professor Sonoike plans to further investigate whether respiration, an opposing reaction to photosynthesis, could actually be helping the efficiency of photosynthesis.
-end-
Article title: Characterization of the influence of chlororespiration on the regulation of photosynthesis in the glaucophyte Cyanophora paradoxa

Published in: Scientific Reports

DOI: 10.1038/srep46100

Waseda University News

About Waseda University

Waseda University is a leading private, non-profit institution of higher education based in central Tokyo, with over 50,000 students in 13 undergraduate and 21 graduate schools. Founded in 1882, Waseda cherishes three guiding principles: academic independence, practical innovation and the education of enlightened citizens. Established to mold future leaders, Waseda continues to fulfill this mission, counting among its alumni seven prime ministers and countless other politicians, business leaders, journalists, diplomats, scholars, scientists, actors, writers, athletes and artists.

Waseda is number one in Japan in international activities, including number of incoming and outgoing study abroad students, with the broadest range of degree programs taught fully in English, and exchange partnerships with over 600 top institutions in 84 countries.

Waseda University

Related Evolution Articles:

Prebiotic evolution: Hairpins help each other out
The evolution of cells and organisms is thought to have been preceded by a phase in which informational molecules like DNA could be replicated selectively.
How to be a winner in the game of evolution
A new study by University of Arizona biologists helps explain why different groups of animals differ dramatically in their number of species, and how this is related to differences in their body forms and ways of life.
The galloping evolution in seahorses
A genome project, comprising six evolutionary biologists from Professor Axel Meyer's research team from Konstanz and researchers from China and Singapore, sequenced and analyzed the genome of the tiger tail seahorse.
Fast evolution affects everyone, everywhere
Rapid evolution of other species happens all around us all the time -- and many of the most extreme examples are associated with human influences.
Landscape evolution and hazards
Landscapes are formed by a combination of uplift and erosion.
New insight into enzyme evolution
How enzymes -- the biological proteins that act as catalysts and help complex reactions occur -- are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.
The evolution of Dark-fly
On Nov. 11, 1954, Syuiti Mori turned out the lights on a small group of fruit flies.
A look into the evolution of the eye
A team of researchers, among them a zoologist from the University of Cologne, has succeeded in reconstructing a 160 million year old compound eye of a fossil crustacean found in southeastern France visible.
Is evolution more intelligent than we thought?
Evolution may be more intelligent than we thought, according to a University of Southampton professor.
The evolution of antievolution policies
Organized opposition to the teaching of evolution in public schoolsin the United States began in the 1920s, leading to the famous Scopes Monkey trial.

Related Evolution Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...