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An Atlantic cod. Nearly 4,600 species of the more than 29,000 known fish species have been barcoded to date. (Credit: NOAA) |
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Scans can differentiate species and verify that the seafood you are served is what you ordered
Most of us are familiar with bar codes, those small black stripes with
numbers below, known as the Universal Product Code or UPC label, that
appear on commercial products. We scan them at the grocery store or to
check a price, or have to cut them out and send them in for a rebate.
Now imagine scanning a DNA barcode on the piece of fish you just bought
for dinner to instantly verify the species, where it came from, its
nutritional value, and other valuable information. NOAA researchers are
helping to make this scenario a reality.
"We
need to accurately identify species for a number of reasons, from
documenting the biodiversity of poorly sampled species and geographic
areas to understanding populations and managing global fisheries in a
sustainable way,” said Bruce Collette, a zoologist at NOAA’s National
Systematics Laboratory (NSL) located in the Smithsonian Institution in
Washington DC. "DNA barcoding is another tool in the toolbox of
taxonomists and researchers who study, document, and organize knowledge
about all life forms on earth.”
Collette and colleagues at NSL, part of NOAA’s Northeast
Fisheries Science Center, are participating in FISH-BOL, the global
Fish Barcode of Life Initiative, which plans to collect at least five
representatives each of all 30,000 plus marine and freshwater species
in the world. FISH-BOL is part of the global Consortium for the Barcode
of Life (CBOL), started in 2003 to barcode everything from fishes,
mushrooms and flowers, to microbes, insects and animals of every
description.
With decades of experience, Collette is among a small
number of taxonomists who conduct the painstaking work required to
identify new species, or re-identify a specimen as new information is
gained. After years looking into microscopes and examining animals
stored in jars, he now spends much of his time working at a computer
screen at his NOAA office deep within the Smithsonian’s National Museum
of Natural History.
"Even though several million species of plants, animals
and microbes have been identified over the past 300 years or so, we
still find new species,” Collette says. “And despite advances in
technology, we still have to sort organisms into piles and research
every known bit of information before we can say we found a new
species. Sometimes we have to go back to the basics and look at an
organism in a jar for reference to make a determination.”
Scientists like Collette often go to sea and collect
dozens of samples of an organism they think might be a new
species. They return to the lab to sort out what they have
collected before focusing in on the details to determine exactly what
the organism is, sharing samples with colleagues to reach a
consensus. The process takes time, and they are excited about the
contributions FISH-BOL and other similar efforts around the world will
make to documenting and understanding life forms on earth.
After
decades of following similar taxonomic procedures often done by visual
identification, DNA barcoding offers a new and much faster, more
accurate way to identify species and share information. Since
nearly all biological species have distinct gene sequences, they can be
identified using a short gene sequence collected from a standardized
position in the genome – a DNA barcode. Barcoding of animals relies on
differences between species in a relatively short segment of
mitochondrial DNA.
The first step in FISH-BOL and other
similar efforts is to build a public library of barcode sequences from
museum reference specimens. Specimens provide tissue samples that
produce a reference barcode for that specific species. Researchers
using standard tools and techniques in molecular biology extract DNA
from the tissue, locate and isolate the barcode region, then replicate
and sequence the genes. Then the specimens, known as voucher specimens,
are preserved and catalogued into archival museum collections.
Not only can specimens be identified as part of a known species using
only a tiny piece of tissue from the organism, but new variations in
what was thought to be a single species can be determined. Tissue from
unidentified specimens can also be matched to the DNA sequence of a
known species in the reference library, a process that currently takes
just a few hours and a few dollars but soon may take only minutes and
cost pennies.
Barcode records of each specimen contain
the DNA sequence, information about the voucher or referenced specimen,
and the species name. The records are stored in three global databases
and are available without charge. As an electronic database, FISH-BOL
contains DNA barcodes, images and geographic information of examined
specimens, as well as linkages to the voucher specimens, information on
species distributions, nomenclature, taxonomic information, natural
history information and literature citations.
"Barcoding
works for all stages in the life cycle, so it will help us identify
larval fish, which is timely since many leaders in larval fish taxonomy
are retiring,” Collette said. “It can also differentiate between
closely related species that are hard to tell apart, especially large
specimens that are difficult to bring back from the field. And it can
positively identify fishery products like fish fillets so you know if
the grouper you ordered in a restaurant is really grouper."
For
fishery managers and researchers, barcoding can legally verify
identifications of fishes caught as by-catch and species under
regulation, important to protecting endangered species and sustaining
fish populations.
Collette and researchers at NSL have
already started adding to the voucher specimens at the National Museum
of Natural History by barcoding fishes in the Gulf of Maine and western
North Atlantic. So far, tissues have been collected from 508 specimens
representing 162 species, including 101 species from the Gulf of Maine
out of the 252 known. He will present some of the group’s results
at the July 2008 meeting of the American Society of Ichthyologists and
Herpetologists in Montreal, Canada.
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NOAA Fisheries Service is dedicated to protecting and preserving our nation's living marine resources and their habitat through scientific research, management and enforcement. NOAA Fisheries Service provides effective stewardship of these resources for the benefit of the nation, supporting coastal communities that depend upon them, and helping to provide safe and healthy seafood to consumers and recreational opportunities for the American public.
The National Oceanic and Atmospheric Administration, an agency of the U.S. Commerce Department, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects. |