The Cellular Effects of Genetically Modified Organisms in Aquatic Environments
DNA Strand

Why Do The Cellular Effects Matter?
When introduced into an ecosystem, genetically modified organisms affect many levels, one being the cellular and molecular level. While the cellular effects may seem of minimal importance since they are so small, these cells and molecules are the building blocks of every living and non-living being on our planet. If the introduction of genetically modified organisms affect these basic building blocks, consequences arise in the organisms we value as food sources and other resources. These changes may occur simply by exposure, or they may occur through ingestion. Though these organisms may affect something as small as a basic bacteria, this may lead to larger consequences in organisms exposed to these bacteria. In a review by Connor (2003) called The Release of Genetically Modified Crops in The Environment, the possibility of contact between non-genetically modified organisms and genetically modified organisms was discussed. This major concern from this contact is the potential for gene exchange between these organisms and the potential negative effects.

~What Are The Actual Effects On Cells By GMOs?~

Genetically Modified Organisms Living in Aquatic Environments
Genetically modified microorgansisms offer many potential benefits to the ecosystem. One example is the introduction of bacteria that break down harmful metals and protect plants and other organisms from harmful pathogens. Despite these positives, there are also concerns about these microorganisms negatively affecting the ecosystem. Though they appear to colonize at the same amounts or less than the original colony, it unlikely for their effects to spread (Viebahn et. al., 2009). While there is some concern that these genetically modified colonies may disrupt others, it is unlikely that they will be able to grow to this size in the environment.
Consumption of Genetically Modified Organisms
In a study performed by Netherwood (1999), birds were separated into control groups and test groups. The control groups were fed non-modified probiotics, while the test group ingested genetically modified probiotics. The study found that the microbial growth in the gastrointestinal (GI) tract varied between the two groups. The birds receiving genetically modified probiotics contained higher levels of the bacteria E. faecalis in their GI tract. During the study the birds did not decrease in health or seem to experience any largely negative effects, however, as the birds were in controlled conditions, further research should be performed to determine if the safety of genetically modified probiotics fed to chickens remain safe. While birds are not an aquatic organism, the effects of GM consumption has the potential to occur in aquatic environments from GM crop runoff.

Bacillus thuringiensis

Gene Transfer From The Consumption of Genetically Modified Organisms
A rising concern for genetically modified crops is DNA transfer. In a study performed on Atlantic salmon, the consumption of genetically modified feed looked at the occurrence of GMO DNA in the tissues of these salmon (Wiki-Nielsen, et. al., 2011). Using PCR, researchers determined that this DNA was transferred to the tissues and organs of the salmon. It is unknown, however, if this DNA can be transferred into the genomes of salmon cells and then expressed by these salmon. Further research on gene transfer should be performed to determine if this could alter the health of individuals or if the DNA from genetically modified feed will react any differently from non-modified foods.
At this point, the effects of genetically modified organisms on the cellular level are not well known. While some studies show positive correlations, others find potential negative effects while many remain unknown altogether. While there are many potential negatives that may extend into the organismal and ecological level, it is important to remember that these organisms as a whole have not been found to be harmful. Like many new technologies, there may be risks with the genetic modification of organisms. Since one huge concern that is being raised is gene transfer, further research should be focused in this area, as the cellular level is the base of all organisms.

Integrative Case Study: How GMOs Affect Atlantic Salmon on The Cellular Level?

Osmoregulation is a necessary mechanism for the survival of fish, and plays an increasingly important role in Atlantic salmon, who travel from freshwater to saltwater during smoltification. The salmon must be able to acclimate and prepare to regulate the increase in salinity as they transfer to a saltwater environment.
Since salmon move between freshwater and saltwater environments, they must maintain the ability to osmoregulate when their tissues are both hypertonic and hypotonic in comparison to their environment (Freeman, 2008). Fish who have hypertonic tissues contain an increased amount of solutes or ions in their tissues than the freshwater they live in. Therefore, freshwater fish take in large amounts of water through their gills and gain electrolytes via active transport. Unfortunately some electrolytes are still lost through the gills during diffusion, so these fish excrete increased amounts of water in their urine to maintain electrolyte balance in their tissues.

In contrast, saltwater fish are hypotonic compared to their environment and must find ways to eliminate the large amount of electrolytes (Freeman, 2008). Since their tissues need fewer solutes than the environment to survive, the intake of water through the mouth must be counteracted by actively transporting electrolytes out of the gills. This mechanism also allows for the intake of solutes via diffusion in the opposite direction of transport into the gills. To counteract this problem, saltwater fish excrete less water than freshwater fish through their urine, allowing them to maintain a safe osmolarity to live.
Studies on non-genetically modified fed salmon have shown that the acclimation of juveniles to increased salinity during non-smolt time periods does not aid in seawater osmoregulation and growth (Handeland and Stefansson, 2002). This study indicates that varying salinity levels of streams should not have an effect on osmoregulation in Atlantic salmon. It is also known that sodium levels and osmoregulation can have an effect on the formation of cataracts in Atlantic salmon (Bjerkas & Sveier, 2003), showing that osmoregulation is an important factor in the health of salmon throughout their lives.

Freshwater Fish

Osmoregulation Photos Found at:

Furthermore, an increase in gill Na+,K—ATPase activity was found in correlation to an increase in growth hormone during smoltification (Handeland, et. al., 2003). This cellular effect may lead to further implications in the reproduction of these salmon, depending on size dependence as well as the population dynamics and the use of resources such as food. In a study focused on the variation of salinity and feed amounts, it was determined that diet is a key factor in osmoregulation as well as the regulation of minerals in Atlantic salmon (Imsland, et. al., 2011).

Marine Fish

Another study showed that Atlantic salmon fed diets of soybean meal instead of fishmeal experienced decreased levels of plasma sodium, but increased amounts of Na+,K—ATPase activity, indicating that diet may affect the osmoregulation in these fish (Bakke-McKellop, 2006). These studies indicate that it is likely that runoff from genetically modified crops could impact the osmoregulation in Atlantic salmon. In one study, researchers found that the consumption of genetically modified crops including soybean and maize do affect cellular function. In Atlantic salmon specifically, the consumption of these soybeans and maize altered cellular D-glucose levels as well as Na-dependent mechanisms like osmoregulation. The study hypothesized that these salmon may recruit macrophages after receiving this modified feed (Bakke-McKellop, et. al., 2008). Since osmoregulation is a key factor in the travel of juvenile salmon from freshwater to saltwater, it is possible that the alterations in these mechanisms may cause adverse effects in reproduction and population dynamics.