How Earth's Atmosphere Changed

A DENSE RAINFOREST or other verdant terrestrial vegetation may be what first comes to mind at the mention of photosynthesis. Yet the clouds of phytoplankton that fill the oceans are the major drivers of that process in nature. 

The plantlike single-celled aquatic microbes generate more than 50 percent of the oxygen in the atmosphere, and they absorb nearly half of the carbon dioxide, converting it into the glucose, fats, proteins and other organic molecules that nourish the food web of the oceans.

A recently published study in Current Biology finally pins down the source of this unparalleled photosynthetic efficiency, which has long baffled scientists. The new research found that some phytoplankton are equipped with an extra internal membrane that carries a “proton pump” enzyme that supercharges their ability to convert carbon dioxide into other substances. 

The enhancements due to this one protein modification seem to contribute to the production of nearly 12 percent of the oxygen in the air and as much as 25 percent of all the carbon “fixed” (locked into organic compounds) in the ocean.

Surprisingly, that photosynthetic innovation seems to have evolved by chance from a membrane protein that was originally used for digestion in the ancestor of the phytoplankton. 

In addition to explaining the cells’ prowess at photosynthesis, the new work helps to confirm the theory that those phytoplankton arose through a symbiotic alliance between a protozoan and a resilient red alga.

“I find it staggering that a proton enzyme that we have known for so many decades is responsible for maintaining such a crucial phenomenon on Earth,” said Dennis Brown, a cell biologist at Harvard Medical School who studies the functions of membrane proteins and was not involved in the study.

Researchers knew that certain classes of phytoplankton—diatoms, dinoflagellates, and coccolithophores—stand out for their exceptional photosynthetic abilities. 

Those cells are extremely proficient at absorbing carbon dioxide from their environment and directing it to their chloroplasts for photosynthesis, but the details of why they are so good at it haven’t been very clear. A feature unique to those three groups of phytoplankton, however, is that they have an extra membrane around their chloroplasts.  READ MORE...

Boosting the Immune System

Understanding which vitamins boost the immune system is imperative. After all, our world is not sterile. Every day, we are exposed to a myriad of harmful microbes that are constantly evolving to get better at infecting us.


Knowing the risks, we often try to do everything in our power to protect ourselves from falling ill. We might put on a jacket, drink some hot tea and head to a pharmacy for some reinforcements. 

But do we know which vitamins boost the immune system? And is it even possible to fight off a cold with certain nutrients, or is it just a marketing gimmick?

It’s hard to understate the role that nutrition plays in maintaining our health and wellbeing. Studies(opens in new tab) have shown that a diet that consists mostly of wholefoods and provides a sufficient amount of good quality protein (our guide to the best protein powder can help if you’re struggling to meet your intake) is key to longevity and improved quality of life. 

However, our immune system is arguably the most complex part of the human body apart from the brain and it may require more than getting few specific nutrients to keep it in peak condition.

Here, we’ll look at whether vitamins can really boost the immune system and which of these nutrients are important for helping you to stay healthy.  READ MORE...

Nutrient Poor Soil

If you're up to speed on nutrition news, you've probably heard talk that large-scale, industrial agriculture can deplete crops of essential vitamins and minerals that our bodies need to thrive. 

But why, exactly, does that happen, and what can be done about it?  For such a massive problem, the solution is actually microscopic. How soil microbes contribute to healthy, nutrient-dense food.

In its natural state, soil is full of invisible but indispensable microbes. Like, really full of them. There are more microorganisms in a handful of healthy soil than humans who have ever lived, and the microbes on our planet outnumber the stars in our universe more than a million times over.

In healthy, symbiotic systems, plant roots feed these soil microbes sugars and give them a place to latch onto. In return, the microbes help the plants absorb nutrients in the surrounding soil. 

All life on Earth depends on this mutually beneficial relationship—but some agricultural practices can mess with it.  READ MORE...

Missing Microbes

Even in the harshest environments, microbes always seem to get by. They thrive everywhere from boiling-hot seafloor hydrothermal vents to high on Mt. Everest. Clumps of microbial cells have even been found clinging to the hull of the International Space Station (SN: 08/26/20).

There was no reason for microbial ecologist Noah Fierer to expect that the 204 soil samples he and colleagues had collected near Antarctica’s Shackleton Glacier would be any different. 

A spoonful of typical soil could easily contain billions of microbes, and Antarctic soils from other regions host at least a few thousand per gram. 

So he assumed that all of his samples would host at least some life, even though the air around Shackleton Glacier is so cold and so arid that Fierer often left his damp laundry outside to freeze-dry.

Surprisingly, some of the coldest, driest soils didn’t seem to be inhabited by microbes at all, he and colleagues report in the June Journal of Geophysical Research: Biogeosciences. 

To Fierer’s knowledge, this is the first time that scientists have found soils that don’t seem to support any kind of microbial life.  READ MORE