George Wooten, an ecologist and teacher, presented the third night of the Methow Conservancy’s Big Ecology course, and he did a wonderful job making the microscopic world around us seem really BIG! The course began three weeks ago with the Big Bang and billions of years of history and science, and last week we focused on the planet and learned about the mechanics of geology. George took it to the next level and he opened our eyes and mind to the complex and unseen world of single cell organisms, and how DNA has created the incredible diversity we enjoy on earth.
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Spotted Lake near Osoyoos contains magnesium sulphate (Epsom salt) that crystallizes in circular patterns during cycles of evaporation (image from GoogleEarth). The lake lies in the Okanogan dolomites, laid down near the Permian-Triassic extinction event of 250 million years ago. These sediments continue south to Omak, where they contribute to the character of the Poison Lakes, including Hot Lake, a polymictic lake that reaches 150 degrees in the summer. Because of the salt concentrations, organisms living in Spotted Lake must tolerate extreme osmotic pressure.
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We started by learning about an incredible body of water not far from the Methow that is filled with naturally occurring Epsom salt (magnesium sulphate). Spotted Lake is covered in a crust of Epsom salt and there are 365 individual pockets of water strewn about, and each one has a unique salinity and chemical makeup. As a result, biologists are able to study a variety of different types of algae that grow in these unique “petri dishes” provided by Mother Nature. The Native Americans used the lake for healing purposes, and they believe the 365 pools represent an enlightenment for each day of the year. The halophiles that live in these pools are microscopic and they are greatly affected by osmosis due to the high salinity of the lake. Through positive and negative feedback, the halophiles are able to change their body shape in order to adjust to varying osmotic pressures, and they use their whip-like tails (flagella) to move about.
Everything in nature is in balance and interconnected and the pink “watermelon” snow we see on the melting mountain snowpack in summer is a perfect example of this. Halophiles live in the frozen glaciers on the mountains and they move towards the light and heat on the surface as the spring melt occurs. Once they arrive at the surface they lose their tails and produce carotenoid pigments which appear red on the snow. The red halophiles absorb more heat than the white snow, which hastens the melting process. Individual pools of water form more quickly, which allows for blooms of algae to begin reproducing. Algae get consumed by protozoans, nematodes, and the food chain is born out of a frozen glacier.
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Amoeba with consumed green and blue-green algae.
Image used with permission of Arturo Agostino (www.microscopeitaly.it).
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The next thing we discussed is how we share DNA with the plant kingdom and even algae. There are 688 overlapping proteins that humans and plants share, which is logical when you consider where life began on earth. Single cell organisms diversified over millions of years and two kingdoms appeared as a result of that: plant and animal. The next step up the evolutionary ladder took us to Euglena and Chlamydomonas, and they each developed two tails and eye spots. They feed on algae so they appear green under the microscope. As single cell organisms began eating smaller single cell organisms like algae and amoebas they created more complicated multi-cell organisms.
Cell membranes developed over time into semi-permeable surfaces that allowed individual cells to control what went in and out of their membrane. The membrane is made up of two layers of proteins, and the layers are lined up opposite each other. There are heads and tails to the proteins and the tails face in towards each other and the heads face towards the outside and inside of the cell. They are packed together tightly but every once in a while there is a channel located in the membrane that creates a specific sized tunnel through the cell wall. These channels work as enzymes do with a lock and key mechanism. They act as ‘gate keepers’ and they are very selective about what they will allow into the cell.
After George opened our eyes to the microscopic world around us and how it developed over hundreds of millions of years, he stepped back and defined life from a biologist’s viewpoint:
1. An organism is any contiguous living system capable of the following functions: Organization / Metabolism (use of energy for consumption, processing, excretion) / Response to stimuli / Homeostasis (maintenance of a stable internal environment) / Growth / Reproduction / Adaptation (maintenance and evolution of beneficial traits).
2. In ecology, a community refers to a group of organisms in a specific place or time.
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| Is it alive?
Aerial view of Grand Prismatic Spring, Yellowstone National Park. The spring is 300 feet wide at the widest. This photo shows steam rising from hot, sterile azure blue water, while on the margins, the vivid colors are the result of pigmented bacteria in microbial mats. The mats are colored from green to red, depending on the ratio of chlorophyll to carotenoids and on the temperature of the water which favors one bacterium over another.
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Back under the scope we continued with a discussion about the building blocks of life, namely carbon. It turns out that the six electrons and protons and the four attachment points or bonds that carbon provides, creates a geometric shape with endless possibilities for building things. Carbon is nature’s ‘plastic’ and the molecules formed by carbon structures are much more complex than if they were triangular or tubal in shape, which explains why organic life on earth is carbon-based.
We explored the double helix world of chromosomes next and the closer you look, the more complicated it gets. Proteins have three structural patterns: Alpha-helix (hair, fingernails), Beta-sheet (silk), and collagen (cartilage, tendons). We learned how Tubulin is a self-assembling polymer and they are critical for sexual reproduction. Tubulin guides the chromosomes in cell division. Peptide chains are created by Ribosomes and they build them by removing the tails from the proteins, while simultaneously linking the heads together. It is through this incredibly complicated and guided process that genetic expression gives rise to individuality and diversity.
Biologists still do not agree on the origin of life on earth. LUCA stands for the ‘last common universal ancestor,’ and there are three schools of thought. Some believe the first life was bacteria and everything evolved from that, while others believe it was Archaea. Other scientists believe the Genetic Annealing Model which states that prior to organisms there were proto-organisms that were less complex and they exchanged genetic information more freely, which allowed for the diversification of species. Scientists study the hot springs at Yellowstone National Park in search of the answers to this question, because the algae that grows inside of them is flowing out of a hot spot in the crust. This unique area provides scientists with a peek into the primordial soup of life.
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No last universal common ancestor (LUCA) of life is known. Although this classification has general acceptance, disagreements continue about the rank of the domains and about the LUCA. It is now generally agreed that many of the most primitive forms are polyphyletic, confounding classification.
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One of the ways life was able to evolve in bacteria is through horizontal transfer of genetic material. A donor bacteria connects to the recipient by means of a tube, or pilus. Only a part of the DNA is transferred, and as a result the recipient bacteria now contains a mixture of DNA. Scientists believe this is one of the ways life has been able to diversify slowly over hundreds of millions of years. We discovered that this type of gene transfer also occurs in ferns. A parasitic flower grows next to the fern and through complex negative and positive feedback, genetic material is exchanged.
The organic and living world around us is constantly recycling itself back into the smallest building blocks, readying them for reuse. Fungi live in communities in the soil and they break down dead and decaying plant and animal materials into the smallest usable components, which are protein subunits. Some fungi live in symbiosis with trees and they receive sugar from the tree in return for the nutrients the host seeds need to grow. When a tree is dying, however, different fungi will move in and begin breaking down the wood.
The one thing we all took away from George’s lecture on Big Biology was how interconnected and complex life on earth is. From the microscopic to the macroscopic, life thrives because of the relationships that exist in nature. The aspen trees protect their young by creating a taste that is unappealing to the beaver. Once the trees mature, however, beavers love to eat them, and new aspen shots grow from the downed trees, and thus aspen trees survive well in beaver country. The deer and the bitter brush also have a symbiotic relationship. The deer survive the winter months by eating the exposed branches, but underneath the snow new growth is forming on the branches still protected by the snow. The pellets left by the deer act as the fertilizer that the bush needs for the spring and summer growth.
The discussion ended with the popular topic of climate change. George discussed something that has been getting a lot of attention these days, which is what role does methane gas play in climate change? There are tremendous amounts of methane gas frozen in the Arctic Circle and climatologists fear that when those pockets of gas are released into the atmosphere that it will accelerate the heating process. The planet is witnessing rapid heating similar to times in earth’s history that preceded mass extinctions.
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