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Antimicrobial Peptides from the Marine Fishes
In this research journal of immunology, the study was done at the "Centre of Advanced Study
of Marine Biology", Annamalai University; by S. Ravichandran, K. Kumaravel, G.
Rameshkumar, and T.T. AjithKumar. This research was conducted to study the antimicrobial
peptide layer of mucous, that is formed around the entire layer of a marine fishes body. This
thick, slimy layer, provides the fish with a form of defense system to protect them from the
pathogenic bacteria, that lives in the ocean. This layer acts is thought to act as a shield, to
provide the fish with a barrier from infections. Listed are a few types of α-helical Antimicrobial
Peptides (AMP) that have been discovered on the fish living in the ocean: Pleurocidins, Parasin,
Pardaxins, Misgurin, Oncorhyncin I and III, Chrysophsin and HFIAP (Hagfish Intestinal
Antimicrobial Peptide). This study was provided will provide a more intricate look at the role of
bioactive peptides. A few of the species of fish these samples are taken from are: Hagfish, Coho
salmon, Winter flounder, Red sea moses sole, Hybrid striped bass & White bass, Loach, and
Asian catfish.
Fish are amongst the largest and earliest class of vertebrates, and contain saprophyic and
pathogenic microbes which give them the ability to digest and degrade fish tissue. The marine
fish have antimicrobial peptide layer, is thought to be able to be used for the cure of the human
body's natural defenses of epithelial cells and mucous membranes. The study is concentrated on
the fishes highly specific cell-mediated immune system. Various animal species, are armed with
different defense mechanisms to assist them with protection from multicellular organisms from
entering their body. The advantage of these antimicrobial peptides, are to assist with function
when lacking high specificity and memory. Some fish embody Antibacterial polypeptides, which
share the same α-helical structure as the antimicrobial peptide sture, which penetrate
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phospholipid membranes. In order to study these structures, Nuclear Magnetic Resonance
(NMR) is used to identify the sequence analysis of each antimicrobial peptide. They are then
classified into five different groups: HelicalAMPs - highly ampthipatic helix, with hydrophobic
snf catonic charged surfaces; Cysteine Rich AMPs - four disulfide bonds and three antiparallel
strands with the helix in between the first two strands; β-Sheet AMP - single hairpin structure,
protegrins, peptides isolated from porcine leukocytes; AMPs Rich in Amino Acids - Histatin,
isolated from human saliva, rich in arginine residues; AMPs with Rare Modified Amino Acids Nisin, a lantibiotic, form unusual cyclic hairpin.
The Thalamita crenata isolates the antibacterial peptide, which is recognized to show
immense activity towards human bacterial pathogens. Then Antibacterial peptides are
synthesized to be stored in-case of another infection. Without this capability to be able to break
down the small foreign molecules within hours, the fish could not possibly survive. The
researchers were able to isolate each a variety of fish to take samples of the type of peptides
found on each fish, the amount (approximate MW and No. of amino acids; between 2.0 - 4.6
kDa), and the region of the fish the sample was taken from. These peptides have been found to
provide natural antibiotics, Apolipoprotiens, numerous isotypes of Muramidase, Squalamine, and
increasing proteins. With the low infection rate of fish, researchers are hoping to discover a new
medicine with these antimicrobial peptides.
The bonds that form in the antimicrobial peptides , are to act as a natural barrier to bacterial
infections. The peptide develops over the pathogen's membrane causing it to change in its net
charge or permeability of its structure. This will lead to changes in its activity. These structures
that are formed, are a net positive charge and an amphipathic nature, which allow them to form a
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bridge to resist foreign bacteria. With humans, they have lactoferrin peptides which can slowly
collapse, causing cell lysis. In order to restore this natural peptide, we must take a antibiotic to
replace the collapsed membrane.
What does this mean for the pharmaceutical companies? A new alternative to an antibiotic
that may assist in the production of endogenous antimicrobial peptides in patients with
deficiencies such as, cystic fibrosis. With the study, it may provide us with a more sufficient and
cost- effective product to replace specific existing antibiotics. Another area of study that is
currently being experimented is for the external human use, to assist with healing of skin
infections, burns, eye infections, and diabetic wounds.
This article is related to our class, because of the physical and scientific relation of marine life
to human life. This study teaches us about the organisms and bacteria in the water that can
penetrate the fishes bodies causing illnesses. With this research conducted by the scientists at the
Centre of Advanced Study in Marine Biology, they were able to show the breakdown of the
antimicrobial peptides that naturally grow the outside of various species of fish, protecting them
from bacterial infections. If they are able to replicate and compound the structure of these
peptides, they can put it into a digestible pill form, and allow humans to consume it to replace
our own membrane loss.
Although, the Oceanography and Marine Biology book does not go into a structural
breakdown of antimicrobial peptides, learning this may help us with future classes and with a
more in-depth comprehension of sea life. We are currently learning about marine vertebrates,
and now I am able to identify one of the natural defense systems that they use in order to survive.
The immunity that the fish are able to tolerate, may be the key to human bacterial defense as
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well. What is also very interesting, is the Atlantic Hag fish is the only fish that has had intestinal
antimicrobial peptides found inside of them. This could be an amazing break-thru if it could cure
or relieve the symptoms of human illnesses such as, Crohn's disease.
We are the next generation of scientists, and with these inquires of scientific studies, it helps
us see a better breakdown of how a study is conducted. Personally, my college goal is to become
a Scientific and Technical Writer, so I thoroughly enjoyed reading and interpreting this research
journal.
Reference
Ravichandran, S. S., Kumaravel, K. K., Rameshkumar, G. G., & AjithKumar, T. T. (2010).
Antimicrobial Peptides from the Marine Fishes. Research Journal Of Immunology, 3(2),
146-156. Retrieved from http://db24.linccweb.org/login?url=http://search.
ebscohost.com/login.aspx?direct true&db=a9h&AN=54320848&site=ehost-live
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6 Additional References
Cledón, M., & Nuñez, J. D. (2010). Siphon nipping facilitates lethal predation in the clam
Mesodesma mactroides (Reeve, 1854) (Mollusca: Bivalva). Marine Biology, 157(4), 737745. Johnson, C. R. (2007). Seaweed invasions: conclusions and future directions.
Botanica Marina, 50(5/6), 451-457. doi:10.1515/BOT.2007.047
Jung, H., Hyun, S., Kim, H., & Choi, J. (2006). Angiotensin-converting enzyme I inhibitory
activity of phlorotannins from Ecklonia stolonifera. Fisheries Science, 72(6), 1292-1299.
doi:10.1111/j.1444-2906.2006.01288.x
Lanfranconi, M. P., Bosch, R., & Nogales, B. (2010). Short-term changes in the composition of
active marine bacterial assemblages in response to diesel oil pollution. Microbial
Biotechnology, 3(5), 607-621. doi:10.1111/j.1751-7915.2010.00192.x
Martinez, A., Tyson, G. W., & DeLong, E. F. (2010). Widespread known and novel phosphonate
utilization pathways in marine bacteria revealed by functional screening and
metagenomic analyses. Environmental Microbiology, 12(1), 222-238.
doi:10.1111/j.1462-2920.2009.02062. doi:10.1007/s00227-009-1357-0
Radulovici, A. E., Archambault, P., & Dufresne, F. (2010). DNA Barcodes for Marine
Biodiversity: Moving Fast Forward?. Diversity (14242818), 2(4), 450-472.
doi:10.3390/d2040450
Zemb, O. O., West, N. N., Bourrain, M. M., Godon, J. J., & Lebaron, P. P. (2010). Effect of a
transient perturbation on marine bacterial communities with contrasting history. Journal
Of Applied Microbiology, 109(3), 751-762. doi:10.1111/j.1365-2672.2010.04706.x
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