Evolution by natural selection is just incredible

Just look what they’ve turned up now: “Biology is capable of evolving functional mechanical gears“.

Through a combination of anatomical analysis and high-speed video capture of normal Issus movements, scientists from the University of Cambridge have been able to reveal these functioning natural gears for the first time. The findings are reported in the latest issue of the journal Science [abstract].

The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box. Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to man-made gears such as bike gears – essentially a shock-absorbing mechanism to stop teeth from shearing off.

The gear teeth on the opposing hind-legs lock together like those in a car gear-box, ensuring almost complete synchronicity in leg movement – the legs always move within 30 microseconds of each other.

Amazing. It’s almost as if someone had designed it. I also saw this the other day which was even more startling:

A paper by a dozen German biologists, while discussing new findings about an ammonium ion transporter, includes descriptions of the many actions that occur when the Venus flytrap snaps shut on an insect.

The traps open wide to the environment, exposing trigger hairs and attractive red leaves.

Electrical action potentials are established for the trigger hairs on the inner leaf surface.

The digestive glands remain quiescent till activated. Abscisic acid regulates their sensitivity, but is balanced by 12-oxo-phytodienoic acid (OPDA), which makes them more sensitive to touch.

A trigger hair on the inner leaf is touched. If only one is touched, nothing happens.

A second touch after a short delay, or touch of a second trigger hair, begins a cascade of events.

Anion channels open. The action potential collapses, activating the motor center.

Vascoelastic energy snaps the trap shut in a fraction of a second.

If the triggering substance was not an animal, the trap re-opens after a short period.

Escape movements by the trapped animal triggers synthesis of a touch hormone, and acidifies the trap.

The trap edge hairs wrap more tightly around the edges, preventing escape.

The trap seals hermetically around the prey like a “green stomach,” exposing it to densely packed glands and chlorine ions.

OPDA stimulates production of jasmonic acid, which triggers the glands to secrete an acidic cocktail with more than 20 ingredients, including chitinases to dissolve the saccharides of the exoskeleton, proteases to dissolve the proteins, nucleases to dissolve the nucleic acids, lipases to dissolve the fats, and phosphatases to isolate the phosphates. These only digest the prey, not the leaf. The proteins are hydrolyzed into their constituent amino acids.

The amino acid glutamine is deaminated into ammonium, NH4+.

Genes to make an ammonium transporter are activated, depending on the action of touch hormones and elicitors, so as to adapt to varying, prey-derived ammonium sources.

The cell membrane becomes depolarized, ready to accept ammonium, even though it is not activated by pH. Only activation of the genes prepares the transporter for ammonium transport.

The ammonium transporter increases uptake of NH4+ from the prey into the plant cells, satisfying the need for nitrogen in the nutrient-poor soils of the plant’s habitat. It is described as “a voltage-dependent high-affinity NH4+ transporter optimised for NH4+ uptake at the membrane potential of gland cells.” Counteracting the acidification of the trap, the transporter can “serve to counter the depolarising effects of electrogenic NH4+ uptake and help to maintain intracellular pH homeostasis.”

“At the same time, progressive acidification of the trap digestive fluid will allow optimal digestion of a wide range of protein and other substrates.” If the pH drops below 3, additional digestive enzymes are synthesized to benefit from the additional NH4+ provided by the insect’s haemolymph.

Upon successful completion of the digestive cycle, the trap re-opens, and action potentials are set up for the next capture.

The world is a mystery but some possibilities are more possible than others, much more possible.

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