Balance of nature: importance of algae in ecosystems (Introduction)

by David Turell , Sunday, November 29, 2020, 20:40 (1454 days ago) @ David Turell

They supply sugars at the base of systems:

https://www.sciencedaily.com/releases/2020/11/201125154808.htm

The next time you visit a lake or the seashore, take a deep breath. As you exhale, take a moment to be thankful for the little things: specifically, for the microscopic, single-celled algae in the soil and waters all around you that are extracting the carbon dioxide you just exhaled and incorporating it into sugars that will eventually be used by every other organism in the biosphere. About 30% of this activity, globally, is carried out by a specialized structure in algae called the pyrenoid.

To visualize a pyrenoid, think of a pomegranate. The pyrenoid contains kernels of Rubisco, the enzyme that carries out the molecular work of incorporating carbon dioxide into sugars. These kernels are embedded in a supportive flesh, or matrix, of other proteins, that is itself surrounded by an outer shell made of starch. The fruit is a bit worm-eaten; it is riddled with fingerlike channels -- actually, tubules enclosed by membrane -- that deliver concentrated carbon dioxide to the Rubisco kernels. The tubules are important to pyrenoid function because waterborne algae such as Chlamydomonas reinhardtii would otherwise struggle to get enough carbon dioxide to keep Rubisco operating at peak capacity.

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"We noticed that the antibody directly bound to several pyrenoid-localized proteins," says Jonikas. In other words, they'd just discovered that all these proteins possess a lock matching their antibody's key. Closer examination of the proteins revealed the existence of a sequence of amino acids, or motif, that is present in the antibody's original target and also appears in all of the other proteins.

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Meyer and colleagues found that the motif binds to Rubisco. This explains how the pyrenoid forms: its component proteins remain loose in the cell until they bump into Rubisco and become trapped.

"Several of the proteins do not simply localize to the pyrenoid matrix, but rather appear to localize to the interfaces between the matrix and the pyrenoid's two other sub-compartments, the pyrenoid tubules and the starch sheath," notes Jonikas. This may allow the proteins to self-organize into the complex pyrenoid structure.

Comment: Food supply lies with the simplest forms (algae) in the beginning of providing nutrition. Pyrenoids are not simply formed and highly suggest an original design. Evolution as designed from the simplest to the most complex follows a very logical progression in which the simplest supports the existence of the complex. dhw constantly tries to dismiss this continuum as not important an incidental consideration in viewing evolution.