From Monsoons to Microbes Understanding the Ocean's Role in Human Health (1999) / Chapter Skim
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5 Marine Organisms as Models for Biomedical Research
5 Marine Organisms as Models for Biomedical Research
Pages 83-96
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From page 83... ...
Although the comparative approach emerged from the tradition of natural history, it has also been used extensively in the disciplines of physiology, biochemistry, and developmental biology. Some of the insights gleaned from these studies include the thermoregulatory role of countercurrent exchange systems in the circulatory system, the biochemical evolution of proteins through duplication of structural motifs, and the role of cytoplasmic segregation in the development of embryos.
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From page 84... ...
The validity of applying results obtained from the study of a protein in a highly modified fish muscle to normal biochemical processes in human muscle derives from the insight that many fundamental features at the molecular and cellular level are highly conserved even though the evolution of animals has shown dramatic changes in morphological form (Gerhart and Kirschner, 1997~. Studies using marine organisms have had a major influence on biomedical research (Sargent, 1987~.
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From page 85... ...
Cell division/cancer Cell physiology, intracellular transport, and cellular pH calcium regulation Cell division/cancer Fertilization and development Organic ion transport Organic ion transport Cellular osmoregulation Detoxification mechanisms Kidney function Insulin secretion and diabetes Muscle pathologies Cystic fibrosis Kidney and heart research Detoxification mechanisms Kidney function
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From page 86... ...
Further research showed that echinoderms (e.g., sea urchins and sea stars) possess the features of a basic immune system, one that involves the non-specific action of phagocytic cells (Smith and Davidson, 1994~.
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From page 87... ...
, which were originally identified in sea urchins (Evans et al., 1983~. The key features of sea urchin eggs that made this discovery possible are their abundance and the synchronous division of cells after fertilization.
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From page 88... ...
The initial signal, calciuminduced calcium release, propagates the waves by successively stimulating calcium receptors in adjacent intracellular membranes, resulting in further calcium release. Based on new results using sea urchin eggs, there are at least two separate calcium stores, each with a specific receptor selectively sensitized by one of two novel endogenous chemicals, cyclic adenosine 5'-diphosphate-ribose (cADPribose)
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From page 89... ...
Thus, the cADP-ribose system that was only recently discovered as a result of continuing investigations of sea urchin eggs appears to be of fundamental importance for mammalian neuromuscular coordination and, with further research, should contribute to advances in the diagnosis and treatment of neuromuscular disorders. MARINE ORGANISMS: THEIR ROLE IN PHYSIOLOGICAL STUDIES PERTAINING TO FLUID AND ION TRANSPORT, RENAL FUNCTION, AND VOLUME REGULATION Marine organisms have proven the value of the August Krogh principle, which essentially states that for every problem in physiology, there is one animal ideally suited to solve that problem.
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From page 90... ...
Osmoregulation at the intra- and extracellular level is made up of the combined mechanisms of fluid and ion transport and solute or organic osmolyte regulation. The principles learned from studying osmoregulation in marine animals has increased the understanding of how the human kidney maintains the blood at 300 mOsm and also how some kidney cells tolerate the osmotic stress generated by the kidney's role in concentrating urine.
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From page 91... ...
and appears to be regulated by mechanisms similar to those regulating urea transport in the mammalian kidney (Wood et al., 1998~. The eye of Squalus acanthias, the spiny dogfish shark, is used to understand mechanisms of vision and fluid formation, with relevance for human diseases that affect intraocular pressure (like glaucoma)
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From page 92... ...
HORSESHOE CRABS: THEIR ROLE IN UNDERSTANDING RETINAL FUNCTION AND HOW EYES SEE Knowledge of human vision has its roots in early 20th century studies of the compound eye of the horseshoe crab and the phenomenon of lateral inhibition (Sargent, 1987~. The horseshoe crab eye has approximately 1000 photoreceptors whereas the human retina has more than 100 million photoreceptors.
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From page 93... ...
Subsequent studies elucidated the biochemical mechanisms of memory storage. The investigators began with a short-term form of learning, sensitization, and studied its effects on one readily analyzable component of the gill-withdrawal reflex, namely the synaptic connections between the sensory and motor neurons.
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From page 94... ...
In 1939 Alan Hodgkin and Andrew Huxley began experimenting with squid giant axons at Plymouth.2 First, Huxley inserted a needle directly into a fiber, intending that they should measure the viscosity of the cytoplasm. When that did not work, Hodgkin and Huxley inserted a glass electrode into the fiber and directly measured the electrical change when a nerve impulse passed.
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From page 95... ...
CONCLUSIONS Although some of the most familiar marine animal models were developed early in this century, the promise of using these organisms in research is rediscovered roughly every decade (NIEHS News, EHP 102:272~. The discovery of marine organisms as useful models for biomedical research has frequently been serendipitous, but many successful marine models have emerged from a thorough understanding of the natural history and basic biology of marine organisms.
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From page 96... ...
~ 989. "Nitzschia pungens as the Primary Source of Domoic Acid, a Toxin in Shellfish from Eastern Prince Edward Island, Canada." Can.
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