Jurassic Park And Tech The girl shrieks as the giant tree trunk of a leg crashes down shaking the earth. Her screams are then drowned out by the prehistoric roar of the genetically engineered Tyrannosaurus Rex as it searches for prey (Crichton, 1991). Everyone remembers this scene from the best-selling novel by Michael Crichton, Jurassic Park. These scenes were then brought to life by producer/director Steven Spielberg in the immensely popular movie by the same name. Is this possible? As technological advances in molecular biology steam into the twenty-first century, many scientists have found themselves asking this very question.
With continuing advancements in the methods of recombining DNA (Deoxyribonucleic Acid), as well as the ability to read its genetic language, people have started wandering just how science fiction these ideas really are. There has been some limited success. DNA has been extracted and processed from some extinct organisms. Single-celled organisms have even been “awakened” from a long endosporic state, that do not exist in the same form in present times. The recent cloning of the sheep “Dolly” at the Rosalin Institute in Scotland has served as a wake up call to many as to the abilities modern biotechnology possesses (Currie and Psihoyos, 1996). Assuming one had all the necessary means, would it be possible to create an extinct organism with all the traits it once held? The answer seems to be yes.
The feasibility of such a thing does not seem too far-fetched when one considers the rate at which science continues to break down barriers in all fields of study. So one final question brought before researchers on projects such as this is: If we could recreate the past through the recreation of long extinct animals, would we want to? Fossils and DNA Deoxyribonucleic acid (DNA) is the chemical basis of life (Campbell, 1996). All cells contain the strands of sugar and phosphate. These strands are held together by the four nucleotides; Adenine, Thiamin, Guanine, and Cytosine. Within these strands are millions of genes.
These are what forms the organism, makes it unique, in essence the blueprints of life. DNA is eventually transcribed and translated into amino acids which carry out the function outlined within the specific gene (Campbell, 1996). It is because of this that many scientists have become skeptical of the ability of DNA to survive much more than a few thousand years. The viability of DNA is tested in this simple way. Amino acids, which are the building blocks of proteins, come in both left-handed and right-handed forms.
Most organisms build proteins using left-handed amino acids known as L-enantiomers. After death, a chemical process known as racemization begins changing L-enantiomers into right-handed D-enantiomers until a balance is reached. Since racemization occurs at approximately the same rate as DNA degradation, scientists can use the ratio of D-enantiomers to L-enantiomers to determine the state of the organisms DNA. If extensive racemization has occurred, the DNA has deteriorated. Researchers have not been able to obtain reliable samples from remains in which the D-enantiomer content has reached ten percent.
At this rate, DNA should break up within a few thousand years in warm climates and 100,000 years in cold climates (Monastesky, 1996). This casts much doubt on the plausibility that resurrecting a long since extinct species is possible. However, as it is not very plausible, it is somewhat possible. This could happen if fossils were to be entombed under certain circumstances that did not allow water, necessary for racemization to have access to the specimen(Monastesky, 1996). The fossils that have been made famous by Crichton are those in which smaller organisms happened to be trapped within tree sap, which later solidifies into the stone called amber.
These fossilized specimens are kept void of oxygen and water (Sykes, 1997). Large amber quarries, such as the ones in the Dominican Republic, yield many fossils of this kind every year. It is this fossil that will be the main focus of DNA extraction in this paper. These are the main culprits in the sudden race among geneticists to be the one to extract and process the oldest DNA. To date, the oldest piece of isolated DNA came from a 125 million year old insect trapped within a bit of Lebanese amber by California Polytechnic Institute at San Luis Obispo researcher Raul Cano (C.F., 1993). Analyzed, the now extinct insect was found to resemble closest the modern day pine cone weevil. However, research is underway to extract protozoa from a 225 million year old piece of amber obtained by Robert Poinar at University of California at Berkely (Richardson, 1994). Extraction The extraction of DNA from a fossilized organism or piece of an organism must be a completely sterile procedure.
The contamination of any other type of organism, including bacteria, could result in a faulty sample. The popular way of eliminating such potential contaminants is using ultraviolet (UV) light. The UV rays mess up some of the chemical components of DNA, effectively eliminating potential contaminating DNA. The sample is shielded from such rays(DeSalle and Lindley, 1997). The ideal specimen would be a piece of an animal, insect, or other organism preserved by its natural surroundings.
Examples of this would be the Mastodon dung discovered in Florida in 1993 that was effectively preserved in sedimentary layers beneath a river bed (AP, 1993), or the preserved remains of a saber-toothed cat that was recovered from the La Brea tar pits in Los Angeles (Grimaldi, 1993). Both of these animals went extinct somewhere between ten and fifteen thousand years ago. Unfortunately, in both cases, no adequate DNA samples were recovered. Finding a fossilized specimen in these states with intact DNA, as stated before, due to the natural degradation processes of organic material is slim (Lewin, 1997). The main focus of DNA isolation is on the various organisms found preserved within amber. In the Crichton book, the suggested way of extracting DNA from an organism is to drill a hole to the organism, and insert a needle (1991). However, this process in reality would be very inefficient (Desalle & Lindley 1997).
By doing this, the needle could inadvertently pick up DNA from something else contained within the amber, or something on the surface of the organism itself. A much more efficient way would be to crack the amber in half at the site if the specimen. One would then proceed to remove pieces of the organism (Cano 1996). Upon dividing the specimen into individual cells, the cell and nuclear membranes must be broken to get to the DNA contained within the nucleus. To accomplish this, the cells are added to a solution with a soapy like detergent substance to dissolve the lipids in the membranes and the enzyme proteinase to break down the proteins allowing access to the DNA itself.
The genetic material is then isolated using an ultracentrifuge. With this done, the isolated DNA is entered into a thermocycle, fluctuating first hot then cold, along with certain polymerase buffers and individual nucleotides. By fluctuating the heat, the DNA breaks apart, then reforms. Through a process known as the polymerase chain reaction which strings together the nucleotides creating a mirror image of the original DNA, the DNA is multiplied exponentially until it reaches a desired amount (Gibbons,1994). The multiple strands of DNA can be used to study evolutionary trends by comparing them to the DNA of related modern organisms, or even attempting to clone a once extinct species. Research Bacteria Bacteria are simple, unicellular organisms and are often used in genetic research because of their haploid strand of DNA, and method of binary fission reproduction (Cano, 1996).
In binary fission, bacteria reproduce by exactly replicating their DNA and then splitting in half. So in essence, bacteria clone themselves to reproduce. George and Roberta Poinar discovered bacteria cells in the remains of the alimentary canal of nematodes preserved in Mexican amber (Poinar, 1994). Bacteria would be a simple starting step for determining a process for, isolating, testing, and replicating DNA of higher organisms in order to ev …