In May 2003, Roderick Mackinnon’s research group at Rockefeller University has published the three-dimensional atomic structure of a voltage-gated potassium channel. MacKinnon also received the Nobel Prize in 2003 for the first potassium channel structure

How electrical signals are conducted through nerve cells has been understood with some detail in the last fifty years, after the seminal work of Hodgkin and Huxley, which earned them a Nobel Prize in 1963. After 40 years, another study is appreciated in the scientific community as the end of one era and the beginning of another one.

Cells, body’s building blocks, are bound by membranes that are impermeable to ions, atoms that carry positive or negative charge. Nerve cells are specialized for having very long arms that can carry electric potentials on their membranes for very long distances. The electric potential (voltage difference) is the result of unequal number of charges across the inside and outside of the cell membrane. Hodgkin and Huxley explained the movement of the electric potential on the membranes by the selective opening of ion channels, proteins embedded in membranes to allow the passage of certain ions. As channels are opened in one part of the nerve cell to allow an electrical potential change, the neighboring stretches somehow sense the change in voltage and open their channels as well. The propagation of the electric potential depends on the fast sensing, opening and closing of these channels. The molecular details of these voltage-gated channels have been somewhat obscure; however important properties have been determined using methods pioneered by Hodgkin and Huxley, generally dubbed electrophysiology, the study of biological material using electrical methods. Scientists

have imagined channel proteins as many helices running through the membrane, some of which could be pulled to the inside or outside of the cell depending on the voltage across the

membrane. Movement of these helices across the membrane could open channels for potassium or sodium. Finally in May 2003, Roderick Mackinnon’s research group at Rockefeller University has published the three-dimensional atomic structure of a voltage-gated potassium channel. MacKinnon also received the Nobel Prize in 2003 for the first potassium channel structure, which explained the selectivity of a potassium channel for allowing only potassium ions to pass, but nothing else.

MacKinnon is a mixed structural biologist and electrophysiologist. His group has isolated potassium channel molecules from membranes, and tested them for strict functionality as it has been observed that protein molecules isolated out of their natural environments may lose their activities and chemical properties. The next step of their study was to crystallize the channel molecules-much like forming salt crystals-and diffract x-rays through the aligned molecules in the lattice of their crystals. These diffraction patterns are mathematically solved to give atomic positions of electrons, hence atoms, in the protein crystal. Several research groups failed at this step, since purified potassium channels never formed crystals, as flexible protein molecules are unlikely to form crystals. Here, MacKinnon cleverly used antibodies they developed specifically against the channel. These antibodies, used radically differently than they are in nature, overcame the flexibility of the voltage-sensing regions of the channel, by binding to the channel and fixing it to a specific conformation. The ordered channel crystallized and gave the structure of the potassium channel and the antibody bound to it.

The structure of the channel consists mostly of helices, which in the center surround a potassium-conduction pore, and “voltage-sensing paddles” in the periphery. When the gate is closed, the helical paddles lay parallel at the cellular side of the membrane. Gate opening only happens when the paddles are pulled through the membrane to the outer side as voltage pulls the positive charge of the paddles to the outside (see figure). Now, it looks like 50 years of data collected by electrophysiologists and biochemists can be explained coherently (such as the observed 14 positive charges residing on the paddles moving through the membrane). As is usual with such discoveries, many new questions are asked, such as how the charged paddles can go through the oily, highly uncharged membranes. There are also valid scientific objections, such as the antibody distorting the potassium channel structure. However, this is one of those bright moments in any field of research, when researchers go over the threshold of collection of enough observations to discovery and understanding.

References

• Jiang, Y., Lee, A., Chen, J., Ruta, V., Cadene, M., Chait, B.T., MacKinnon, R., Nature 423, 33-41 (2003).
• Jiang, Y., Ruta, V., Chen, J., Lee, A., MacKinnon, R., Nature 423, 42-48 (2003).
• Sigworth, F.J., Nature 423, 21-22 (2003).

Wilson Bentley took the first photomicrographs of a snowflake, thereby initiating extensive research on the snowflake. When he was 15 years old, his mother gave him a microscope as a gift. He began studying several things under the microscope, among them raindrops and snowflakes. Later on, he discovered how to photograph this delicate ice formation and presented it to the world. His enthusiasm for photographing snowflakes continued until his death 47 years later. Through his photomicro graph collection, we can see just what a complex and wonderful creation each snowflake is and why it has been the subject of such debate over the years.

The average snowflake is made up of 2 to 200 separate snow crystals; much larger ones can contain as many as 1,000 separate snow crystals. These snow crystals begin to form around tiny dust particles that have been carried up high into the atmosphere. When the temperature drops below freezing at these high altitudes, water vapor clings to these dust particles. Interestingly, the water vapor skips the liquid state and turns directly into ice, a process called sublimation. When the air contains enough moisture and the ice crystals accumulate, these crystal formations begin to fall as snow.

Scientists believe that there are only four different types (shapes) of these six-sided snowflakes; hexagonal plates, stellar stars, stellar and plate combinations, and spatial dendrites. Hexagonal plates are thin, solid, or partly snow crystals. This pattern is made up of a variety of ridges and hollows, as well as thick and thin ice. The stellar star pattern is the one many know as the symbol of a snowflake. It assumes this pattern because ice crystals tend to cling together in “cottony” clumps and have the corners of a star, unlike hexagonal plates.

The stellar and plate combination pattern is formed when plate and stellar star characteristics unite. The resulting flake is considered the most exquisite of all crystals. The plate pattern is in the middle, and the stellar star branches out from the plate. Finally, the dendrite, another stellar type, is identified by small crystals that branch out, fern-like, along each of its six “rays.”

It is believed that the shape of the snow crystals forming these snowflakes depends on the temperature of the cloud in which it is formed. Ice crystal columns are formed in the highest clouds, which have the lowest temperatures. Dendrites and star-shaped crystals are formed in the slightly warmer middle clouds, and needle ice crystals are formed in the lower clouds. These temperature variations cause each snowflake to assume a specific shape. Different sources give slightly different temperature ranges and different explanations of a snowflake’s developmental stages. This may be to the fact that scientists do not have exact knowledge of the conditions and formation of these delicate crystals, for they base their assumptions on laboratory experiments that seek to create the same weather conditions. It must be pointed out, however, that all snowflakes “created” in laboratories are always deformed and do not resemble the perfectly symmetrical flakes found in nature.

The first wonder I would like to describe is the snowflake’s construction. Nuclear physicists and crystallographers are still trying to explain this complex bridgework of molecules that form the ice crystals into a snowflake. A brief explanation behind the construction mystery is that an average hexagonal-shaped crystal may contain 100 millon more water molecules. The ice crystal grows by adding more and more molecules. Its growth proceeds in a way that is both perfectly horizontal and perpendicular, thus building a broader and thicker crystal. Amazingly, this process is always carried out within the same hexagonal symmetry.

An ice crystal’s framework is a marvelous example of solid geometry, for it always presents an ingenious grouping of molecular parts. Not only does the ice of a snow crystal grow perpendicularly by interlocking pyramids, but at the same time its horizontal ice particles extend themselves in overlapping hexagonal patterns.

But not all of a snowflake’s beauty can be seen with the naked eye. Each crystal contains an invisible masterpiece of construction resembling an ongoing pattern that becomes smaller and smaller. Such a development is produced by the ice crystals themselves, which bond to each other and thereby increase the snowflake’s size. Over a period of 15 minutes, and under the conditions necessary for sublimation, a snow crystal gradually assumes the shape of the first stage. This baby crystal is unbelievably tiny, from .008 to .009 of an inch in diameter.

The average initial crystal may appear as hexagonal plates, sector plates, various stellar forms, or as capped columns. This later shows evidence of a skeletal structure, surface design, and pattern that subtly determine the snowflake’s final pattern. Later, this plain star will begin to develop either crystal twigs or fern-like plumes. As the final ice structure becomes heavy, it begins its journey to the ground.

An additional wonder is that no two snowflakes are alike! Each snowflake has a unique combination of ice crystals, which creates a unique snowflake. No two identical snowflakes have been found.

Another mystery is why each snowflake has six sides. Johannes Kepler, a physicist and mathematician, has studied this for years. In his The Six-Cornered Snowflake, he mentions some very important and thought-provoking questions and explanations. He also states that there must be an agent for such perfection and calculation, some definite reason why a snowflake’s initial form invariably displays the shape of a six-cornered starlet. Why always six? If this were the result of chance, should not some of them at least have five or seven corners?

In his search for a logical reason for the six sides, he asserts that if you ask geometers on what plan honeycombs are built, they will respond “on a six-cornered plan.” Each cell is surrounded by six others, each of which ends in an obtuse angle, pointing downwards, formed on three planes. The architecture causes each cell to share six walls with six cells surrounding it in a row, and also three plane surfaces with three other cells from the contrary row. Each bee, as a result, has nine neighbors.

Kepler also observed that the insides of such fruits as pomegranates and peas are squeezed into six sides. Why? One reason, perhaps, is that a plane surface can be covered without gaps by only three shapes: a triangle, a square, and a hexagon. Of these, the hexagon is the roomiest, and so has the most storage space, for example, for the honey produced by bees. Therefore, bees instinctively build their hives in this shape rather than others. Why and how?

Kepler concludes that this original, well-thought-out pattern can only have been imprinted on it by a Creator: our Creator. He concludes that the cause of each snowflake’s hexagonal shape is the same cause that shapes plants and numerical constants. Nothing happens without a reason, but rather with a reason guided by a Supreme Reason.

The wonder of the snowflake is seen not only in its wealth of variety and form, which is perfectly constructed with complete beauty and perfection, but also in how these six-sided crystals are formed with perfect symmetry by various processes in the clouds.

As I mentioned earlier, such findings are merely realizations of a fact. The term realization is used because discoveries like these have been in existence since the beginning of time! They have always been around us and will continue to be. But now we can see some of these small miracles due to recent, rapid advances in technology. This displays to us more about the reality, existence, and attributes of the Creator. Yet even a tiny snowflake shows us, through sight and reasoning, the attributes of our Creator. Among these attributes are artistry in creation, finality in creation, countenance, and divine teaching and directing.(1)

Artistry in creation: “The whole of creation exhibits an overwhelming artistry of dazzling worth. Yet it is brought into being, as we see it, easily and in a very short time. Furthermore, creation is divided into countless families, genera and species and even smaller groups, and each of these exists in great abundance. Despite the variety and abundance, we see only orderliness and art and ease in creation. This shows the existence of one with an absolute power and knowledge, who is God.”

For example, each snowflake is literally a masterpiece of art, with a perfectly eye-appealing design. It is remarkable that such a masterpiece is created within minutes in the clouds, yet has perfect symmetry and a complex pattern. This is the first attribute of our Creator that we see when we look at a photo of a snowflake. Hence, our Creator is a master in artistry.

Finality in creation: “Nothing in the universe is for nothing, pointless. As ecology in particular shows, everything in creation, no matter how apparently insignificant has a very significant role in existence and serves a certain purpose…. There are many purposes for every thing, every activity, and every event in it. Since this requires a wise one who pursues certain purposes in creation, and since nothing in the world-except for man-has the consciousness to pursue those purposes, the wisdom and purposiveness in creation necessarily point to God.”

An example is the snowflake. The causes for it and its six sides, which point to certain reasons, are still being examined. If something cannot be explained at this point in time, all it means is that we have yet to understand its complexity.

Countenances: “[Uncountable] human beings have lived since man’s first appearance on the earth. Despite their common origin-a sperm and ovum, which are formed from the same sort of foods taken by the parents-and although they have all been composed of the same kind of structures or elements or organisms, every human being has an individual countenance distinguishing him or her from the others…. This obviously shows one with an absolutely free choice, and all-encompassing knowledge, and He is God.”

Just as each snowflake is different in pattern and type, no snowflake has been identified as identical with another, even though uncountable snowflakes fall each year. This truly points to a Creator with an unbelievable attribute of countenance.

Divine teaching and directing: “For man to direct himself in life and distinguish between what is good or bad for him needs a minimum of around fifteen years. However, many animals can do this very soon after they come into the world. A duckling, for example, can swim as soon as it hatches. Ants start to dig nests into the earth when they get out of their cocoons. It does not need a long time for bees and spiders to learn how to make their honeycombs and webs, respectively, while each are marvels of handiwork beyond the capacity of man…. How can you explain all these astounding facts otherwise than by attributing them to the teaching or directing of one who knows everything and has arranged the universe with all creatures in it in a way that enables every creature, big or small, to direct its life?”

The snowflake is an example of such directing. How can a snowflake, which is completely devoid of intelligence and consciousness, create itself in such an absolutely perfectly manner within a matter of minutes? Such events can only be the result of Divine teaching and directing.

In conclusion, I would like to highlight two points. First, such astonishing facts exist all around us. Yet in order to appreciate them, first we must observe our surrounding environment and consider its complexity, purpose, and perfection. Second, acknowledging that we have limited senses and that our technology continues to advance rapidly, I am excited about all of the other wonders in this world that might be revealed to us, for all of them will enable us to better understand and marvel at our Creator.

FOOTNOTES

1. The four following attributes are taken from Fethullah Giilen, Understanding and Belief: The Essentials of Islamic Faith (Kaynak, Turkey: Kaynak, 1997), 4-8.

REFERENCES

• Bell, Corydon. Wonder of Snow. New York: Hill and Wang, n.d.
• Blanchard, Duncan. The Snowflake Man. Weatherwise: 1970.
• Gulen, Fethullah. Understanding and Belief: The Essentials of Islamic Faith. Kaynak, Turkey: Kaynak, 1997.
• “How Do Snowflakes Form?” Lansing State Journal. October 8, 1997.
• Kepler, Johannes. The Six-Cornered Snowflake. Clarendon Press: 1966.