Barnacles, Darwin and Marine Paint Research
by Jonathan R. Matias
July 1, 2009
Having
been a fish developmental biologist in my younger days and a biomedical
scientist in my middle years, my own passion for barnacle research did not come
until later, after meeting Prof. Dan Rittschof at Duke University Marine
Laboratory and Sister Avelin Mary at Sacred Heart Marine Research Centre
(SHMRC) in the early 1990s. Barnacles are not exactly the cute furry creatures
one can get passionate about, so I have to admit that the interest was
partially clouded by my capitalistic pursuits. That was the time when the ban
on tributyl tin (TBT) was just looming on the horizon and there was a mad pursuit
to discover the ultimate nontoxic barnacle settlement inhibitor. The search for
TBT-free antifouling was the ‘holy grail’ of the marine paint
business.
Before discussing my version of business evolution at Poseidon Ocean Sciences,
I wish to digress a little to talk about Darwin and the barnacle. Like many of
us in this business, we write about the barnacle, Balanus amphitrite amphitrite Darwin, and yet do not give any thought to why
Darwin’s name came to be part of this nomenclature. So, let me tell you why.
Charles Darwin
The
Charles Darwin we are all familiar with is the English naturalist who wrote On the Origin of Species by Means of Natural
Selection in
1859, which has since become the foundation for our
understanding of evolution and the unifying explanation for the diversity of
life on earth. He wrote about his theory in 1844, then quickly shelved it
inside his desk drawer, specifically instructing his wife to release it for
publication only if he died unexpectedly. Darwin was a modest man who shied
away from controversies, and he knew his theory would be controversial; it
remains so even on this year’s 150th anniversary of writing On the Origin of Species.
For 20 years, this document remained hidden
until he received a letter from a young English naturalist, Alfred Russell
Wallace, then living in an island of what is now Indonesia. In a malarial fit,
Wallace remembered reading Thomas Malthus’ 1798 Essay on the
Principle of Population (which coincidentally also inspired Darwin) and
reached his own Eureka moment totally independently. He quickly
dispatched a letter to Darwin describing an almost identical theory of
evolution. In the typical Darwin sense of fair play, he presented Wallace’s
ideas and his own at the same time during the meeting of the prestigious
Linnean Society, giving equal credit to the idea of Wallace and the share of
the controversy as well. Yet, Darwin is credited with the theory of natural
selection because his ideas were written while Wallace was yet in his teens,
over 20 years before.
Then, you may ask, what did he do for those 20 years? Besides dealing with his
failing health and the tragedies in his life, he was consumed by the passion of
cataloguing barnacles. His interest in these tiny, ugly creatures began during
his famous around-the-world voyage in HMS Beagle. Then, at the age of 26, young
Darwin was exploring the Chilean coastline looking for biological specimens
when he came upon a conch shell with its thick shell riddled with tiny
boreholes. Inside the hole was a microscopic creature, attached by its head to
the shell and waving six tiny legs. Knowing that it was a barnacle without a
shell, Darwin became even more fascinated since it had never before been
described by any naturalist. He was a disciplined taxonomist and organized the
chaotic nomenclature of this organism that number over 1000 species. Most of
the species were often misnamed during his lifetime. Upon his return to England
and immediately after writing his ideas on natural selection, at great expense
to his health, he began his day and night obsession with barnacles that lasted
for eight years (1846-1854), cataloguing the collection from his voyage and
from the hundreds more sent to him by mail from around the
world.
What drove this
passion about such a mundane organism? Perhaps a clue comes from an earlier
anonymous publication in 1844 of a controversial, incendiary, speculative book,
Vestiges of the
Natural History of Creation
(later confirmed to be the work of Robert Chambers, a Scottish medical
journalist). Widely panned and mocked for its evolutionary ideas even by
Darwin’s friends, the failure of the book was a great personal disappointment
because Darwin expected a similar response to his own ideas in On the Origin of Species. Even his best friend, the noted botanist
Joseph Hooker wrote, “no one has the right to examine the origin of species who
has not minutely described many.” Perhaps, one reason for this obsession was
indeed to minutely observe a distinct part of the natural world and in so doing
earn his right to question their origins. Whatever the reason might be, Darwin
started us all on a path of research towards understanding barnacle biology and
the commercial opportunities that follow in its wake.
Development of Poseidon Ocean Coatings Research
Though
not as dramatic as Darwin’s, my adventure towards discovering the ultimate
barnacle settlement inhibitors followed similar paths as many of us. The 1990s
was a time when marine biotechnology was in its heyday and a lot a promise for
a ‘cure all’ was just beyond the horizon. Scientists were extracting every
marine organism they could get a hold of and looking for bioactive chemicals.
For us in the marine paint industry, the goals were purely mercenary – finding
one chemical, that ‘magic bullet’ that would bring great income opportunity
especially for fledgling companies like mine.
At the time, the main workhorse in barnacle
research utilized the method developed by Dan Rittschof called the barnacle
cyprid assay, which still remains the best method to date. Here, the larvae are
artificially cultured until they reach the stage called cyprid when they are
competent to attach to surfaces. The cyprid assay still remains the best
screening method to date. But, it was labor intensive and needed a green thumb
to culture the barnacle larvae (and all the microalgae needed as food to
sustain them artificially). Considering the sheer number of chemicals I wanted
to test and the limited time available, Dan Rittschof suggested I collaborate
with Sister Avelin Mary, who was his post-doctoral student and had since
returned to India to establish her own laboratory. Sister Avelin got her Ph.D.
in biology to become one of India’s most celebrated marine scientists. Because
the internet had not yet reached her place in the port city of Tuticorin in the
mid-1990s, collaboration depended solely on snail mail and fax (both unreliable
even at the best of times) between New York and Tuticorin. I often wonder at
how patient we were in those days. Yet, we were able to identify an active
fragment from the purified extract called juncelin, named after Sister Avelin
and the soft coral, Juncela. Through computer simulations of the structure of
the fragment, we were able to identify the molecular structures that likely
would repel barnacles, not kill them.
Barnacle Inhibition Development
Finding a barnacle inhibitor that will have any remote
chance of being commercial must meet a major hurdle – the cost. Marine paint
biocides are an industrial commodity, huge volumes at low cost; a commodity
that should cost no more than US $100 per kilogram. Knowing what the structure
should look like, we began cross-matching known compounds that are relatively
cheap and used either as food ingredients or in pharmaceuticals for human and
veterinary use. This was Poseidon’s Natural Bioproducts Screening Programme.
Our presumption was that we would likely find from such a known inventory a series
of compounds, we referred to as the NB series, with similar structures that
were reasonably safe and could be mass produced cheaply. Years later, we
narrowed our search of NB compounds to small molecules with menthol-like
configurations, finally settling on a menthol derivative called menthol
propyleneglycol carbonate, a GRAS (generally recognized as safe) food
ingredient used as cooling agent in chewing gum and cosmetics (Figure 1). This
chemical, based on tests, had repellent characteristics not only against
barnacles, but also flies, mosquitoes, termites and even head lice. I suppose
barnacles are nothing more than simply bugs in the sea! No wonder agro-chemical
companies are taking their crop protection chemicals and testing them out
against barnacles too. We just did it the hard way, starting from the ocean.
Millions of dollars of R&D money and a decade later, I was hoping for a
more exotic looking chemical besides a menthol derivative.
|