第17章バイオテクノロジーとゲノミクス

Since 2005, automated sequencing techniques used by laboratories are under the umbrella of next-generation sequencing (deep sequencing or massively parallel sequencing), which is a group of automated techniques used for rapid DNA sequencing. These automated low-cost sequencers can generate sequences of hundreds of thousands or millions of short fragments (25 to 500 base pairs) in the span of one day. These sequencers use sophisticated software to get through the cumbersome process of putting all the fragments in order.

British biochemist and Nobel Prize winner Fred Sanger used a bacterial virus, the bacteriophage fx174 (5368 base pairs), to completely sequence the first genome. Other scientists later sequenced several other organelle and viral genomes. American biotechnologist, biochemist, geneticist, and businessman Craig Venter sequenced the bacterium Haemophilus influenzae in the 1980s. Approximately 74 different laboratories collaborated on sequencing the genome of the yeast Saccharomyces cerevisiae, which began in 1989 and was completed in 1996, because it was 60 times bigger than any other genome sequencing. By 1997, the genome sequences of two important model organisms were available: the bacterium Escherichia coli K12 and the yeast Saccharomyces cerevisiae. We now know the genomes of other model organisms, such as the mouse Mus musculus, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis. elegans, and humans Homo sapiens. Researchers perform extensive basic research in model organisms because they can apply the information to genetically similar organisms. A model organism is a species that researchers use as a model to understand the biological processes in other species that the model organism represents. Having entire genomes sequenced helps with the research efforts in these model organisms. The process of attaching biological information to gene sequences is genome annotation. Annotating gene sequences helps with basic experiments in molecular biology, such as designing PCR primers and RNA targets.

DNA microarrays are methods that scientists use to detect gene expression by analyzing different DNA fragments that are fixed to a glass slide or a silicon chip to identify active genes and sequences. We can discover almost one million genotypic abnormalities using microarrays; whereas, whole-genome sequencing can provide information about all six billion base pairs in the human genome. Although studying genome sequencing with medical applications is interesting, this discipline dwells on abnormal gene function. Knowing about the entire genome will allow researchers to discover future onset diseases and other genetic disorders early. This will allow for more informed decisions about lifestyle, medication, and having children. Genomics is still in its infancy, although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities.

In addition to disease and medicine, genomics can contribute to developing novel enzymes that convert biomass to biofuel, which results in higher crop and fuel production, and lower consumer cost. This knowledge should allow better methods of control over the microbes that industry uses to produce biofuels. Genomics could also improve monitoring methods that measure the impact of pollutants on ecosystems and help clean up environmental contaminants. Genomics has aided in developing agrochemicals and pharmaceuticals that could benefit medical science and agriculture.

It sounds great to have all the knowledge we can get from whole-genome sequencing; however, humans have a responsibility to use this knowledge wisely. Otherwise, it could be easy to misuse the power of such knowledge, leading to discrimination based on a person's genetics, human genetic engineering, and other ethical concerns. This information could also lead to legal issues regarding health and privacy.