 |
|
 |
 |
 |
|
 |
|
 |
|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
Molecular Biology in Marine Research Jane Thompson Division of Biomedical Marine Research Harbor Branch Oceanographic Institution Molecular biology techniques are important new tools for exploration and excavation of the ocean. These new research tools will answer questions about ecology, biodiversity, evolutionary genetics and systematics of marine organisms. Along with the knowledge gained about the biology of the oceans, the marine environment is a tremendous resource for yet to be discovered bioactive natural products. Natural products are chemical compounds that provide new sources of antibiotics, antitumor compounds or anti-inflammatory agents. Since 30% of the drugs now being used are based on natural products, the marine environment is very important for new discoveries of drug sources and cures for disease. Most scientists recognize that 
collections from the sea should be limited and harvesting from the worlds
oceans are likely to deplete overall resources. Important to every phase of research is the sustainable
use of the ocean's resources. Molecular techniques makes this possible through the isolation of
important genes and the production of biomedical compounds through recombinant technology.
The techniques now being employed include: DNA extraction, RNA extraction, the use of agarose gel electrophoresis to visualize DNA and RNA, polymerase chain reaction (PCR) and sequencing for genes of interest. As a result of ocean exploration research, genomic libraries of marine organisms can be made which preserve all the genes (DNA) found in that organism. From genomic libraries, a gene that makes an important biomedical compound can be cloned and expressed as a chemical compound in an artificial system. The Process Research for the Molecular Biologist begins when samples of marine organisms reach the surface. The samples are given a unique identifying number and small pieces (1-2 grams) are quickly frozen. The frozen sample is later thawed at 4 degrees C and homogenized in an extraction buffer that dissolves all the cell's membranes to release nucleic acids (DNA and RNA). An organic extraction is performed to 
remove proteins, fats, and other organically soluble compounds, leaving nucleic acids in the aqueous
solution. Nucleic acids can then be precipitated with ethanol and stored for the trip back to the
laboratory. After resuspending the precipitate, DNA extractions are visualized on agarose gels (electrophoresis)
to determine concentration. Agarose is a product from algae that can be heated to a liquid, poured
into a mold and cooled to a solid. Small indentations are placed into the hot liquid and this provides
a "well" to load the DNA into the solid gel (Fig. 1). The gel is placed under a salt buffer, an electric
charge is applied from one end of the gel to the other. This will allow us to see the DNA and estimate
concentration or simply the amount we have (Fig 2). Once DNA concentration is known, other techniques can
be employed. Polymerase chain reaction (PCR) is an important technique for establishing the presence of
a particular gene in an organism. Small amounts of sequence of that gene must be known. These known
sequences (primers) serve to prime the reaction that amplifies the gene of interest.
For example, in the search for new antitumor compounds, primers from a conserved class of antitumor compounds can be used to find the presence of this type of gene in new organisms. PCR may also establish unique identity for a marine organism. The regions employed to establish identity are usually ribosomal RNA genes from microbes (16S) or from invertebrates (18S). The product of this PCR is then sequenced, resulting in a unique pattern of individual basepairs (ACTG) (Fig. 3). The oceans remain our last great frontier of research to be done. The potential for discovery is tremendous. Molecular Biology provides exciting new tools for discoveries that will advance biology, biochemistry and medicine.  |  |
| ||