[posted: 2.15.17/lmost recent edits: 2/18/17]

Preamble: to propertly address this topic, we need to produce more thorough documentation than we currently have ready for posting. But because we feel the topic is important, we are posting our base notes and comments below. A more complete argument will be presented in the coming months.

Hypothesis: Our intent is to demonstrate how the earth generates a substantial tidal acceleration on all moving fluid bodies - even one as small as an average eukaryotic cell. When acting on a stationary body, this tidal acceleration produces only a one-time distortion, but when acting on a cell residing in our active animal bodies - tumbling and rotating with each manipulation of our arms and legs - the acceleration produces new stresses, strains - they are not trivial. Such distortions necessarily produce very small (tidal) currents that we believe are critical to mobility in the cell. This is especially intriguing when considering too that the viscosity within the nuclei of eukaryotic cells is lower viscosity than the viscosity found in the cytosol, for distortions will initiate stronger currents in the low viscosity regions. Conjecture is offered which considers how mRNA must be directed out of the nucleus towards distant organelles such as ribosomes, and how tidal currents become a potentially useful mechanism. Conjecture is further offered about how our resting position while sleeping may be seen as advantageous to the cell for the tidal stresses become constant and tidal currents are reduced except during the brief moments where the individual might toss and turn.

The tidal force is defined in astronomical bodies by the difference in force that an external mass produces on any particular point of a body relative to the force that the external mass produces on the center of the body. Such tidal forces are generally slow changing and cyclical. And, of course, tidal forces from the moon and sun assist in many of the large-scale life-sustaining patterns associated with earth activities. But, the tidal acceleration produced by the moon and the sun on a fluid body the size of a eukaryotic cell (roughly ~10^-5 meters) are very very small - of order 10^-19 m/s^2. Accordingly, it is hard to imagine how these tides might play any significant role in cell activity. However, there is another small gravitational force acting on the cell that is often overlooked - one that is roughly 100 million times larger that the tidal force from the moon and sun - the tide produced by the earth's gravitation. It is often overlooked because the earth seems stationary as we stand upon it rather that circling around us in the sky each day. But tidal forces are generated by relative orientation, and each time our bodies move or rotate, our cell experiences a new wave of tidal forces. While the tidal amplitude is small, it operates in the background of cell activity - lightly compressing and relaxing the cell. The acceleration is estimated to be - roughly 10^-11 m/s^2 - small, but not zero.

The tidal acceleration on a cell due to the earth is calculated in the graphic below. The magnitude is small, relative to our more familiar scales of motion, but at the cellular dimensions it is signficant. The graphic comment in blue at the right points out that (if unrestrained) even such a small acceleration as 10^-11 m/s^2 can move an object the diameter of a cell in about a half-hour.

The acceleration is more complicated to resolve in a restrained fluid body like the cell that has a cytoskeleton and pockets of varying vicosity and assorted particulates. However, one clear aspect of how this force acts (as noted above) is that any change in orientation of the body relative to the external mass can produce a change in the tidal stress. As a body moves about during the day, constantly changing its large-scale orientation relative to the earth, the orientation of the tidal force also changes - in a very related and predictable way; elongation along one axis, compression in the other two. Rotations about a horizontal axis are more significant than rotations about a vertical axis. (This relationship is much like the pressure changes we experience when we rotate our bodies about different axes. If we rotate our body position about a vertical axis, say, one where we are facing west, to one where we are facing east, we usually don't notice any internal stress changes - howver, if we rotate such that our standing position is transformed into a position where our head is lower than our feet, we notice significant changes in pressure.) It may be thought that this would be problematical for the cell, for it must then adapt to each of these tidal distortions - metaphorically sloshing around like the fluid in a water balloon that is jiggled and squeezed.

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But the conjecture that follows is just the opposite: that the cell uses the tidal forces generated by the earth - acting on the large scale orientation of the body - to its benefit. For, with each tidal distortion comes a tidal current, and with each tidal current comes an opportunity to use the power and direction in these currents to assist in the manipulation of proteins, molecules, and organelles around in the cell. If the cell coordinates local structures along these currents, and manipulates internal viscosity (via temperature) then a very direct comparison can be found with how cities located near rivers and tides use the changing currents to transport materials.

By such conjecture, such tidal currents should play a much smaller role in plant cells since their orientation relative to the earth is substantially constant. Indeed, from an evolutionary perspective, the eukaryotic cells of insects and animals would have had to learn how to manage the internal tidal currents before they could survive and take advantage of the mobility experiment.

Please return here in the late spring for the full discussion.

The text and diagram below are the same as that found on the home page summary.

The tidal accelerations produced by the moon and the sun on a fluid body the size of a eukaryotic cell (roughly ~10^-5 meters) are very small - of order 10^-19 m/s^2 - and it is hard to imagine how they might play a significant role in cell activity. However, there is another small gravitational force acting on the cell that is often overlooked - that produced by the earth's gravitation. The earth produces a tidal acceleration that is roughly 100 million times larger than that from the sun or moon, but it is often overlooked because the earth seems stationary as we stand upon it rather that circling around us in the sky each day. But tidal forces are generated by relative change, and each time our bodies move or rotate, our cell experiences a new wave of tidal forces. The acceleration is still small - roughly 10^-11 m/s^2 - but it is not zero. The energy associated with such repeated accelerations is just large enough for the cell to take notice. Thus, might organelles have evolved a method for harvesting this resource and managing their motion so they could put this energy to use?

[By such conjecture, there are fewer tidal currents expected at night when the body is sleeping and less active. ....

[Notes to include patterns of motion observed with the CLOCK/per and genes such as Per {1,2,3} and Cry {1,2} which cycle in and out of the nucleus.]


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