Thursday, October 14, 2010

Heat Shock Proteins in Fish

In recent years, an issue that has been presented numerous times through the media is the over harvesting and resulting depletion the oceans fisheries. As a result of this, much research has been done in efforts of preserving these fisheries, through such efforts as sustainable harvesting, and ensuring that the fish are healthier. A recent journal article from the Journal of Fish Disease relates to the topic of fish health and is called Heat shock proteins (chaperones) in fish and shellfish and their potential role in relation to fish health: a review. This article discusses various aspects of Heat Shock Proteins (HSPs) and the benefits that they are capable of producing in fish.

First of all, what are HSPs? HSPs are proteins that are found in all cells and the resulting cellular organisms which undergo stress. There are several different types of stress that an organism can face, including not enough food, wounds and the resulting infections, exposure to pollution in water, overexposure to Ultraviolet (UV) light, uncharacteristic temperature variance in the water, and any change to the fish’s environment that would affect it in an unfavourable way. When cells are exposed to these stresses, it makes it more difficult for them to survive and reproduce properly. To counter this, HSPs are released in greater numbers to counteract the effects that the stress is causing on the cell.

There are three levels to this stress. The first is the introduction to the element of stress. The second is where the cell or organism attempts to deal with this element of stress. The third level is if the organism or cell was unable to deal with the stress, then the resulting death of that organism or cell. The role of HSPs is to help to prevent the cell or organism from reaching the third level, especially at the cellular level. While HSPs are only based at the cellular level, they are crucial for maintaining cell growth during stressful periods of time.

Heat Shock Protein

However, the focus of this journal review was not about the defining and describing of HSPs, but the ways in which they could be used to improve both the health and the harvest of fish populations. Due to the fact that HSPs will make a cell, and thus an organism more resistant to a stressful situation, this could have numerous uses. By increasing an organism’s level of HSPs before introducing them to a stressful situation, they would be much more likely to come out of that situation alive and unharmed than they would have been able to do otherwise.

One example in how scientist were able to do this was by introducing shrimp into an environment that was 37°C for 30 minutes, followed by a 6 hour interval of normal conditions. The larvae were 100% more likely to survive than the same shrimp that had not been introduced to the increase in temperature. Tests showed that the more successful shrimp had a significant increase of HSPs in their bodies.

This is also not the only example of how HSPs have increased survival rates. Up until recently, the only way to increase HSPs safely in fish was by raising the temperature of the environment that the fish were in. However, there are now compounds which can increase HSP values without the shocking temperature changes. Pro-Tex® is one of these compounds and is made from a compound which is withdrawn from the skin of the prickly pear cactus. This compound was given to a group of three hundred thousand salmon before transportation from the 16°C water temperature that the fish had been living in to the 6°C water temperature that the fish were being taken to via well boat. The journey would take six days, over rough water. With the use of Pro-Tex®, the fatality rates were much lower than they had been during previous trips, thanks to the increased levels of HSPs.

There are countless theories currently being applied to the preservation of the fisheries. One of these theories was the use of Heat Shock Proteins, and it appears to be working. By allowing the fish to be healthier while alive, and then having less of a fatality rate while harvesting, it is another step towards bringing the fisheries back up to healthier levels.

Adam Gibson




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