THE black and white barcode on goods giving product data such as name, price, shelf number and sell-by date in order to automate the supermarket check-out process has inspired scientists to formulate a similar method of identifying biological species.
If successful, naturalists, zoologists or simply travelers in tropical regions will be able to carry with them a barcode scanner that can tell them the species, genus and other relevant details of any plant or creature.
This tool could be of immense help. For example, if bitten by a mosquito or other insect, scanning the culprit or a part of it could either confirm or dispel any worries in just a few minutes about contracting a virus.
Insects’ bodies contain a DNA barcode that this apparatus can scan and give fast and accurate information. Since its application in the field of biology in recent years, this technology has been developed in China.
Entry-Exit Inspection and Quarantine staff in Zhongshan City of Guangdong Province recently found fly pupa in imported waste paper. Normal procedure would be to send these samples to the lab for analysis. Technicians would then have to wait at least two weeks for the pupa to transform into flies before testing them.
DNA barcoding technology enabled lab technicians to match the unknown pupa with those at the U.S. Genbank of National Institute of Health and identify the insects as Calliphora vicina within five days.
The barcode thus reduced the process by two to three weeks.
Last May, the International Barcode of Life iBOL Scientific Steering Committee signed a Memorandum of Un- derstanding with the Kunming Institute of Botany of the Chinese Academy of Sciences (CAS). Initiated by Canadian scientist Paul Hebert, known as “father of DNA barcoding,” the project’s firstphase aim is to acquire five million DNA barcode specimens from 500,000 species within five years.
“This project is a large-scale life sciences plan follow-up to the genome project,” director of Kunming Institute of Zoology of CAS and academician Zhang Yaping said. Over the years, taxonomy experts have been looking for faster methods of differentiating species. So far, more than 70 scientific research institutions in China have carried out DNA barcode research on biological specimens.
Biological taxonomy is a basic research method. Three centuries ago, Carolus Linnaeus (1707-1778), father of modern taxonomy, set out to give all things a specific name for the sake of scientific understanding and research.
He formulated a binomial nomenclature. Although not the first person to use this method, it was Linnaeus who standardized and popularized it among biologists. Before the study of taxonomy came into existence, biologists had to rely on appearance, color, anatomic characteristics — even behavior — to identify animal and plant species. This was time-consuming and by no means 100 percent accurate.
Taxonomy has benefited greatly from scientists’ determination of the structure of DNA in 1953. Since 1990 and the maturation of DNA sequencing technology, growing numbers of genome sequences have been identified, and comparisons of these data have provided answers to many questions.
DNA has hence provided the hereditary blueprint for determining the evolutionary relationships among both plants and creatures. Paul Hebert’s DNA barcode, however, stands alone in being able to identify biological specimens through a segment rather than going through the entire genome sequence.
The challenge scientists face is that of pinpointing the DNA segment at the same location in the same species as that of the shared genome. A barcode scanner can be used on any part of the segment, in a similar way as a GPS, to read its DNA sequence and send the information to a reference database–a DNA barcode bank. This provides the name and image of the species and detailed information on it. Anyone, anywhere, therefore, can identify a known species or pinpoint one as yet undiscovered.
Genes from the barcode originate in Cytochrome-c Oxidase in mitochondrion (COI). Mitochondrial DNA is the DNA located in organelles called mitochondria — structures within eukaryotic cells that convert the chemical energy. It has a set of independent DNA and a much higher mutation rate than nuclear DNA depicting the evolution of the creature. Hebert chose 650 COI base pairs (bp) as the saved barcode. Two creatures having different barcodes signifies that even though they might have a common ancestor during a certain historical period, albeit while on different evolutionary paths, they are not of the same species. The apparatus has an effective scale of gene detection throughout the world of around 600 genes. “One any longer would not be reliable, but one any shorter would not be accurate,” researcher at the Institute of Microbiology of the Chinese Academy of Sciences and vice director of national key laboratory of mycology Bai Fengyan explained.
Chen Shilin, a researcher at the Institute of Medicinal Plant Development at Peking Union Medical College of Chinese Academy of Medical Sciences, is convinced of the advantages of DNA barcoding technology: Only one or a few genome segments are needed to identify certain families or genera of species; the results, even for large amounts of specimen tests, are available after a relatively short period of time. The process is standardized and easy to operate and automate. It does not involve large amounts of human resources for carrying out identifications, and the sequencing information of existent specimens can be administered and shared through the Internet or an information platform.
“DNA barcoding technology speeds up standardization when identifying Traditional Chinese Medicine ingredients. This implies a wider scope of innovation within the TCM production and circulation cycle,” Chen said. Owing to plant diversity, there are always variations, large or minor, within a species. The species, the area in which they are produced and other factors all lead to changes or even differences in the chemical composition of TCM ingredients. Strict identification is hence a vital first step in producing, researching and prescribing it. Both the quality and effect can thus be preliminarily guaranteed.
The traditional way of identifying traditional Chinese medicine ingredients is through their properties, ap- pearance and microscopic features. This requires years of experience and study on the part of TCM practitioners in order to recognize and know the features of all types of medicinal plants. As senior, experienced practitioners dwindle, the shortage of human resources in this field constitutes a substantial challenge. The DNA barcode, therefore, represents a huge step in identifying traditional Chinese medicine ingredients.
“The traditional method is limited by the high demand for experienced practitioners and for accuracy and efficiency. This prevents it from meeting the needs of a modernized, industrialized medicine industry. New ways are needed to keep up with rapid development,” post doctorate Ma Xinye at the Institute of Medicinal Plant Development said. Ma added that the application of DNA barcode for quality tests throughout all cycles of TCM planting, processing and production will guarantee its clinical efficacy and safety, standardize the circulation cycle and promote the TCM industry as a whole.
