Darwinian Evolution Lab Report

Nick Schemmel
Mrs. Belcher
HNRS Biology, Hour 2
20 March 2018
Darwinian Evolution on a Chip http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0060085 Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce. Evolution is change in the heritable characteristics of biological populations over successive generations. Computer control of Darwinian evolution has been demonstrated by multiplying a group of RNA enzymes in a microfluidic appliance. The RNA group was tested to prepare the
connection of an oligonucleotide, which is a polynucleotide whose molecules contain a relatively small number of nucleotides the substance of which an enzyme acts under conditions of steadily lower substrate concentrations. The scientists said on page one of the PLOS journal article, “It is a microchip-based sequential dilution circuit automate an exponential growth phase followed by a 10-fold dilution, which was repeated for 500 log-growth iterations. Evolution was observed in real time as the population adapted and achieved progressively faster growth rates over time. The final evolved enzyme contained a set of 11 mutations that conferred a 90-fold improvement in substrate utilization, coinciding with the applied selective pressure. This system reduces evolution to a microfluidic algorithm, allowing the experimenter to observe and manipulate adaptation.” The foundation of Darwinian evolution are key to understanding biological organization and have been applied to the development of functional molecules in the test tube. Laboratory evolution is greatly accelerated compared with natural evolution, but it usually needs a good amount of change by the experimenter. This experiment describes a system that relies on computer control and microfluidic chip technology to automate the directed evolution of functional molecules, subject to precisely defined parameters. The scientists used a population of billions of RNA enzymes with RNA-joining activity, which were challenged to react in the presence of progressively lower concentrations of substrate. The enzymes that did react were amplified to produce progeny, which were challenged similarly. Whenever the population size reached a predetermined threshold, chip-based operations were executed to isolate a fraction of the population and mix it with fresh reagents. These steps were repeated automatically for 500 iterations of 10-fold exponential growth followed by 10-fold dilution.
We observed evolution in real time as the population adapted to the imposed selection constraints and achieved progressively faster growth rates over time. The microfluidic system used in the experiment allowed the scientists to perform Darwinian evolution experiments in much the same way that one would execute a computer program. The chip-based evolution system consists of a microfluidic device mounted on a temperature-controlled stage and monitored by an inverted confocal fluorescence microscope. A laptop computer controls the actuation of valves on the chip and the acquisition and processing of fluorescence data indicate the concentration of RNA enzymes within the microfluidic circuit. The circuit consists of a joining loop with three in-line valves for mixing and two bus valves that control the input of fresh reagents and the output of spent reaction materials. This device can perform sequential dilutions in a quick and accurate manner. The experimenting scientists said on page one, Each iteration of events on the chip entails an incubation step with slow mixing, an isolation step in which one-tenth of the reaction mixture is
retained in part of the circuit. “Fresh reaction materials are drawn into the remainder of the circuit, and a rapid mixing step in which the isolated aliquot is combined with the fresh reagents. The reaction mixture contains thiazole orange, which intercalates into nucleic acids and upon laser excitation gives a characteristic fluorescent signal. When the fluorescence reaches a predetermined threshold, correlating with a 10-fold increase in the concentration of RNA, the computer initiates an automated 10-fold dilution.” Continuous evolution on the chip was initiated with randomized variants of the ligase RNA enzyme. This finalized the laboratory evolution and created another advancement in the scientific world.
Biology is the natural science that involves the study of life and living organisms including their physical and chemical, function, development, and evolution.
Biologists use the theory of evolution to explain how living things have changed over time. While taking the course biology, I have learned that all living things link together, and this is shown through science, religion, and other important values in most everyone’s lives. The theory of evolution is created by Charles Darwin, well known scientist, who claims that all life is related and has descended from a common ancestor. Darwin says that every species descends from another with modifications creating the new, modified species. Over the past years to make us Homo sapiens, our ancestors must have evolved to become, smarter, stronger, and more suitable at surviving the present. This is what happened on that laboratory chip. The article shows evolution when The lecture says that all species came from a common ancestor, and we all have come from a common ancestor. But just like the organisms on that laboratory chip, we have adapted from our previous selves and have become more human and we will continue to evolve and adapt to become even more human. Without evolution, I would not be writing this today and no one would be reading this
tomorrow.