April 20, 2018 | David F. Coppedge

Living Things Show Cleverness in Many Ways

Wherever biologists and microbiologists look, they find organisms solving problems in remarkably clever ways.

Cell Calculus

Cells respond to surface curvature in clever ways (Science Daily). Did you know microbes act like A-students in Calculus-III class? Calc III tends to focus on problems in 3-dimensional curved surfaces. This article, based on work at the University of Pennsylvania, shows how cells respond to changing curvatures like math champs. Who taught them?

Last year, researchers from the University of Pennsylvania revealed surprising insights into how cells respond to surface curvature. Specifically, they investigated how cells respond to cylindrical surfaces, which are common in biology. They found that cells change the static configurations of their shapes and internal structures.

We think of it as the cells doing calculus; the cells sense and respond to the underlying curvature,” says Kathleen Stebe of Penn’s School of Engineering and Applied Science.

Now, the researchers, led by Stebe and recent engineering graduate Nathan Bade in collaboration with Randall Kamien of the School of Arts and Sciences and Richard Assoian of the Perelman School of Medicine, have published a follow up study that Stebe likens to “calc III” for cells, investigating how cells respond to more complex geometries.

Sea Turtle Magnets

Sea turtle hatchling in open ocean (Illustra Media, this and next photo).

Evidence that Magnetic Navigation and Geomagnetic Imprinting Shape Spatial Genetic Variation in Sea Turtles (Current Biology). This open-access paper (a bit rare for this journal) continues amplifying knowledge that the Illustra film Living Waters showed: how sea turtles find their way through the trackless seas over thousands of miles. There’s enough variation in magnetic field intensity at each beach, the authors say, for the hatchlings to “imprint” on the magnetic coordinates of their native beach and find their way back years later. What they found may also help explain other animals that use geomagnetic navigation, such as the salmon shown in the Illustra film.

Here, we present evidence for an additional, novel process that we call isolation by navigation, in which the navigational mechanism used by a long-distance migrant influences population structure independently of isolation by either distance or environment. Specifically, we investigated the population structure of loggerhead sea turtles (Caretta caretta), which return to nest on their natal beaches by seeking out unique magnetic signatures along the coast—a behavior known as geomagnetic imprinting. Results reveal that spatial variation in Earth’s magnetic field strongly predicts genetic differentiation between nesting beaches, even when environmental similarities and geographic proximity are taken into account. The findings provide genetic corroboration of geomagnetic imprinting. Moreover, they provide strong evidence that geomagnetic imprinting and magnetic navigation help shape the population structure of sea turtles and perhaps numerous other long-distance migrants that return to their natal areas to reproduce.

Plant Sunblock

How does plant DNA avoid the ravages of UV radiation? (Science Daily). “If the ultraviolet radiation from the sun damages human DNA to cause health problems, does UV radiation also damage plant DNA? The answer is yes, but because plants can’t come in from the sun or slather on sunblock, they have a super robust DNA repair kit.” A genetic repair toolkit called nucleotide excision repair is especially robust in plants. Not only that, it responds to the day-night cycle (the diurnal circadian clock), becoming more active when needed in sunlight.

Credit: University of Bristol

Seaweed Opal

New type of opal formed by common seaweed discovered (University of Bristol). In this example of a clever trick, the researchers at U Bristol are not exactly sure why the organism does it, but the common brown alga seaweed manufactures biological opals. Opals are known for the iridescent colors produced at different angles. The seaweed not only imitates the gemstone, it can switch it on and off. The scientists like the trick so much they want to imitate it.

Such structures arise from nanosized spheres packed tightly in a regular way and are known to optics experts to reflect different colours from incoming white light into different directions. These types of structures are also seen naturally in gem stone opals, which comprise a nanostructure of tiny spheres of glass formed within hard stone deep below the earth’s surface that naturally pack together in such a way that they diffract light into different directions giving the opal it’s well-known opalescence….

In a process unknown to present nanotechnology, the seaweed’s chloroplasts-containing cells (which aid photosynthesis) self-assembles the oil droplets into a regular packing. Surprisingly, these seaweeds can switch this self-assembly on and off, creating changing opals which react to the changing sunlight in tidal rockpools. Even more remarkable is how the seaweed performs the dynamic self-assembly, over a timescale of just hours, is a true mystery to the research team.

Hikers on rough terrain. Licensed from Corel Professional Photos (this and next photo).

Human Gaze Gaiting

Gaze and the Control of Foot Placement When Walking in Natural Terrain (Current Biology). We don’t want to leave out people as cleverly-equipped organisms, too. This open-access paper explores how the brains, eyes, legs and feet of us upright walkers solve the problem of keeping ahead of the terrain. A hiker negotiating a rocky trail has to maintain a balance between watching her feet and looking ahead. Most of us learn to do this trick without much thought, but it is very complex. The scientists outfitted hikers with headsets that allowed measurements of where they were gazing as they walked on level ground and proceeded onto rocky terrain.

Human locomotion through natural environments requires precise coordination between the biomechanics of the bipedal gait cycle and the eye movements that gather the information needed to guide foot placement. However, little is known about how the visual and locomotor systems work together to support movement through the world. We developed a system to simultaneously record gaze and full-body kinematics during locomotion over different outdoor terrains. We found that not only do walkers tune their gaze behavior to the specific information needed to traverse paths of varying complexity but that they do so while maintaining a constant temporal look-ahead window across all terrains. This strategy allows walkers to use gaze to tailor their energetically optimal preferred gait cycle to the upcoming path in order to balance between the drive to move efficiently and the need to place the feet in stable locations. Eye movements and locomotion are intimately linked in a way that reflects the integration of energetic costs, environmental uncertainty, and momentary informational demands of the locomotor task. Thus, the relationship between gaze and gait reveals the structure of the sensorimotor decisions that support successful performance in the face of the varying demands of the natural world.

The research highlighted four major findings:

  • Gaze and full-body kinematics were recorded during real-world locomotion
  • Walkers show distinct gaze strategies appropriate for the demands of each terrain
  • Nevertheless, walkers also adopted a constant look-ahead time across all terrains
  • Walkers tune gaze behavior to sustain consistent locomotor strategy in all terrains

Outdoors humans. Credit: Corel Pro Photos.

 

 

So there you have it. You may not have even known about the optimizing strategy your mind and body utilize in the simple act of walking down a path. You are a wonder walking through a world of wonders. Give thanks to our Creator, and study His marvelous designs in creation.

 

 

 

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