Shrimp on a Treadmill
Scientists often want to know what kinds of effects a particular environmental variable
has on an organism. Organisms can be taken into the laboratory to study the effects
of individual variables.Our work with low oxygen and bacterial infections of marine
organisms has led us to develop a challenge model where we have begun measuring
the performance of organisms under controlled conditions. A shrimp encountering
a bacterial infection has mechanisms to fight this infection, but, like humans fighting
an infection, the shrimp may not be as physically fit.
This shrimp has been injected with a dose of a common shrimp bacterial pathogen.
We have begun measuring a variety of physiological variables as the shrimp respond
to this bacterial challenge. Our early studies indicate that the shrimp are severely
stressed by bacterial injection and, while they are able to completely eliminate
the injected bacteria, their performance suffers.
Research from Atoms... to Ecosystems: New NMR Technology Shows Great Promise
Scientists at NCCOS’s
Hollings Marine Laboratory (HML) in Charleston, S.C.,
have some powerful new technology available to them in the form of two just-installed
world-class nuclear magnetic resonance (NMR) instruments.
The new technology is expected to be a focal point of the Laboratory’s plans
to address a range of human health and coastal ocean research areas of prime importance
to NCCOS and its HML partners.
“With this new facility, our scientists will be able to relate truly molecular-scale
information to complex ecosystem issues,” according to NCCOS scientists Dan
Bearden and Peter Moeller, whose enthusiasm for their new research potential is
tangible. “Our new NMR capabilities will have the capacity to address most,
if not all, of the key environmental stressors affecting the coastal ecosystem.”
What’s so impressive about the new NMR capabilities is the breadth of the potential
- Structural biologyinvolving the shape and function of large biomacromolecules
having thousands of atoms (DNA, RNA, proteins, etc.);
- Metabolomicsinvolving the study of metabolites in an organism,
the byproducts and small building blocks essential for life to go on;
- Natural products researchin which chemists look for commercially
viable chemicals with interesting effects or properties from naturally occurring
The new NMR capabilities will help scientists better investigate, for instance, climate
change effects on organisms at the structural biology level and also at the functional
level, providing insight into how organisms react to subtle environmental changes.
In keeping with the HML’s fundamental goal of facilitating complementary research
among its five institutional partners, the
new NMR capabilities will address both important human medical issues and also important
marine ecosystem health issues. As one example, the
Medical University of South Carolina’s ongoing cancer research will
benefit in new ways along with the HML’s marine research community, as both
benefit from studies of anti-cancer compounds derived from marine sources and from
potential uses of naturally occurring marine toxins (natural products and their
At the same time, HML coastal ocean scientists will have access to tools of structural
biology developed through the cancer research, bringing new insights to the marine
Making Sense of Simple, but Important, Questions
NMR will help the scientists make sense of some seemingly simple — yet profoundly
important and complicated — questions:
- What is this stuff? And how much is there?
- How is this material different from other things we know about?
- Have we manufactured or synthesized the right product?
- How does this chemical reaction happen precisely?
- Is this material pure?
- Can we make this drug work better?
- Is this person or animal sick? If so, what is the possible diagnosis? Is the treatment
Simple questions, with vital implications. For the trained clinician, chemist, or
biochemist, the new NMR capabilities just now taking shape in Charleston can provide
a wealth of valuable information in addressing those questions. They can lead to
a better understanding of the “conceptual framework for understanding living
organisms,” says Bearden. “The ultimate goal would be to bring together
the knowledge to get an accurate picture of living organisms.”
Significantly, the NMR technology itself is non-destructive to the sample, meaning
other potentially destructive tests can later be applied to the same sample. Furthermore,
it is quantitative, so scientists can analytically determine the quantity of material
in a sample, and it can provide very quick analyses and provide detailed data about
the atomic connectivity in molecules. In addition, NMR can be used in studying the
movements of atoms in solids, liquids and gases.
“It is really important to emphasize,” according to Bearden, “that
NMR is essential for identifying and characterizing previously unidentified chemicals.
There is enough information available in NMR data from organic compounds, for example,
to identify the compound unambiguously, down to the details of the stereochemical
structure.” While other technologies work well for known compounds, Bearden
says, they often require extensive libraries or reference compounds for making positive
identifications. “The non-destructive nature of NMR lets us look and re-look
at novel molecules, asking all the pertinent questions we have,” Moeller emphasized.
Like any technology, NMR is better suited in some applications than in others. In
most cases, NMR requires a sample of more than 100 nanograms for a low-molecular
weight compound, and that much material can be difficult to come by in natural products
chemistry, for instance. Even so, recent advances are bringing that limit down by
a factor of 10, “opening new approaches which would have been neglected previously,”
according to Moeller.
In some cases, techniques other than NMR may be more suitable, for instance in working
with unknown crystalline substance, X-ray crystallography may provide a quick automated
way to answer questions directly. Sensitive techniques like Gas Chromatography⁄Mass
Spectrometry might be preferred in working with a known molecule at low concentrations
in a complex mixture, if the molecule is volatile. Liquid Chromatography⁄Mass
spectrometry is used if the molecule is less volatile. Again, however, those non-NMR
techniques are destructive of the samples, and meticulous care is needed to avoid
destroying the molecules’ structure and avoid misinterpreting the resulting
Characterizing Specific Chemicals, Developing Population Assessment Tools
The Hollings researchers have on the drawing board detailed plans for developing
profiles of known anthropogenic contaminants and impacts on marine organisms. For
instance, by comparing responses of a pesticide with responses of other pesticides
or contaminants, they hope to develop tools to characterize new chemicals of interest
or perhaps develop new population assessment tools.
“As we develop this model for other classes of compounds,” Bearden explains,
“we should be able to distinguish modes of action characteristic of the class
of compound for that organism. We then hope to apply those techniques to other important
species, developing corresponding models for exposure, and widening our ability
to assess modes of actions for new compounds across numerous species.”
Another application: Focusing on rare, endangered, or protective organisms on which
classical toxicological research is infeasible. Coordinating with marine mammal
scientists, the HML scientists are obtaining samples of body fluids — urine,
plasma, and stomach contents — and using NMR-based techniques to examine the
samples. They are looking for patterns that may correlate with age, sex, geographic
location, or apparent disease states.
Looking ahead, Bearden says that, “The exciting thing about NMR-based research
is that the technology and tools of NMR continue to evolve at an exciting pace that
could not have been envisioned not so long ago. The utility of NMR has grown with
the computer revolution, of course, but fundamental advances in the field continue
“Applying modern high-field NMR to marine issues can be risky, as with all
cutting-edge science,” Moeller and Bearden say. “But the unexplored
territory is vast, and if we are to address the complex issues of the 21 st Century,
we need all the understanding we can manage.”
Calling it a “fool’s errand” to try to guess just where the NMR
technological capabilities may be just a decade from now, Bearden says that successfully
managing human interactions with the environment “must cover the scale of
atoms to ecosystems. And NMR is a tool that can do that right now.”