7 Genomic Approaches in Aquaculture and Fisheries
237
Molecular technologies in general can clearly have a direct positive impact on
many of the main elements of fish health management. PCR, real-time PCR and
nucleic acid sequence-based amplification (NASBA), by enabling the rapid detection, identification and quantification of extremely low levels of aquatic pathogens,
are crucial for a more effective disease management, which in turn leads to a
reduction in the use of antibiotics and chemicals in the environment. Microarray
technologies offer a new dimension to multiplex screening and understanding
of host–pathogens interaction. Recombinant DNA technology permits large-scale,
low-cost vaccine production. Moreover, DNA vaccination, proteomics, adjuvant
design and oral vaccine delivery are foreseen to foster the development of effective fish vaccines in the future (Adams and Thompson 2006). Several recent reviews
have assessed the development and future potential of genomic tools to improve
health and stress mediated status in fish (see Dios et al. 2008, Martin et al. 2008,
Prunet et al. 2008).
The environmental impact of fish farming is also a major concern and is closely
associated with excessive feed wastage and sub-optimal nutrient utilization. The
inefficient digestion of phytate phosphorus (main form of phosphorus in plant ingredients) by fish has created environmental concerns associated with phosphorus
pollution from aquaculture production facilities. To further complicate this situation,
phytate is also known to chelate minerals and proteins, making them nutritionally
unavailable to fish (Kaushik 2005). One on going strategy involves supplementation of fish feeds with phytase to degrade phytate into inorganic phosphorus, which
can then be directly utilized by fish (Vielma et al. 2000). As a model to examine
the feasibility and efficacy of producing fish capable of degrading phytate, Japanese
medaka (Oryzias latipes) transgenic for an Aspergillus niger phytase gene were produced and their ability to utilize phytate phosphorus tested (Hostetler et al. 2005).
Cell culture techniques, including transfection, RT-PCR, Northern blot, Western
blot, and enzyme activity analysis demonstrated that the protein was expressed and
actively secreted, without compromising survival and growth, suggesting that similar transgenic approaches could be used in the future for farmed fish to solve this
problem.
7.5.4 Seafood Safety
Safety is among the most important food quality issues. To date, the use of genomics
in food safety has concentrated on two main areas, the safety evaluation of food
components (Ommen and Groten 2004) and the detection of microorganisms which
may cause food spoilage or be hazardous to human health (Abee et al. 2004). Safety
evaluation in food is generally focused on both, hazard identification (whether a
food item causes an adverse health effect), and hazard characterization (the level of
exposure required to elicit an adverse health effect). Gathering appropriate data for
hazard analysis can be costly and time consuming, requiring detailed toxicological
experimentation in animals. Genomic technologies can offer alternatives to classical
237
Molecular technologies in general can clearly have a direct positive impact on
many of the main elements of fish health management. PCR, real-time PCR and
nucleic acid sequence-based amplification (NASBA), by enabling the rapid detection, identification and quantification of extremely low levels of aquatic pathogens,
are crucial for a more effective disease management, which in turn leads to a
reduction in the use of antibiotics and chemicals in the environment. Microarray
technologies offer a new dimension to multiplex screening and understanding
of host–pathogens interaction. Recombinant DNA technology permits large-scale,
low-cost vaccine production. Moreover, DNA vaccination, proteomics, adjuvant
design and oral vaccine delivery are foreseen to foster the development of effective fish vaccines in the future (Adams and Thompson 2006). Several recent reviews
have assessed the development and future potential of genomic tools to improve
health and stress mediated status in fish (see Dios et al. 2008, Martin et al. 2008,
Prunet et al. 2008).
The environmental impact of fish farming is also a major concern and is closely
associated with excessive feed wastage and sub-optimal nutrient utilization. The
inefficient digestion of phytate phosphorus (main form of phosphorus in plant ingredients) by fish has created environmental concerns associated with phosphorus
pollution from aquaculture production facilities. To further complicate this situation,
phytate is also known to chelate minerals and proteins, making them nutritionally
unavailable to fish (Kaushik 2005). One on going strategy involves supplementation of fish feeds with phytase to degrade phytate into inorganic phosphorus, which
can then be directly utilized by fish (Vielma et al. 2000). As a model to examine
the feasibility and efficacy of producing fish capable of degrading phytate, Japanese
medaka (Oryzias latipes) transgenic for an Aspergillus niger phytase gene were produced and their ability to utilize phytate phosphorus tested (Hostetler et al. 2005).
Cell culture techniques, including transfection, RT-PCR, Northern blot, Western
blot, and enzyme activity analysis demonstrated that the protein was expressed and
actively secreted, without compromising survival and growth, suggesting that similar transgenic approaches could be used in the future for farmed fish to solve this
problem.
7.5.4 Seafood Safety
Safety is among the most important food quality issues. To date, the use of genomics
in food safety has concentrated on two main areas, the safety evaluation of food
components (Ommen and Groten 2004) and the detection of microorganisms which
may cause food spoilage or be hazardous to human health (Abee et al. 2004). Safety
evaluation in food is generally focused on both, hazard identification (whether a
food item causes an adverse health effect), and hazard characterization (the level of
exposure required to elicit an adverse health effect). Gathering appropriate data for
hazard analysis can be costly and time consuming, requiring detailed toxicological
experimentation in animals. Genomic technologies can offer alternatives to classical