Aquaculture?
Aquaculture Why is the most rapidly growing agricultural field in the world Consumption of aquaculture products is expected to grow 400% in the next 20 yrs. 75% of all rainbow trout raised for food in the U.S. are raised in Southern Idaho
World production of fish for food, 1995-2050
160
High Medium Low
Food needed from aquaculture to sustain current levels of consumption based on three population projections Food available from inland catches
Fish (millions of tons)
140 120 100 80 60 40
Food available from marine catches
20 0 1995 2005 2015 2025 2035 2045
Most Efficient 1lb. 1lb.
=
Food conversion in fish nearly 1:1
Identify if there are genetic differences in fish that utilize alternative dietary sources more or less efficiently. What specific metabolic pathways and enzymes are involved and how the expression or activity of these genes modulate utilization.
Energy Metabolism in Fish
Proteins primary for energy and growth Fats energy and membranes etc. Carbohydrates 2nd for energy behind fats and proteins Fish don't utilize carbohydrates very well yetTheir nervous system runs only on glucose.
Glucose Metabolism
Glucose Glucokinase Glucose 6-phosphatase Glycogen Synthase Glycogen (+3 steps)
Glucose 6-phosphate
Fructose 6-phosphate Phosphofructokinase
PENTOSE PHOSPHATE PATHWAY
Fructose 1, 6-bisphosphatase
Fructose 1, 6-phosphate (+5 steps ) Phosphoenolpyruvate Pyruvate Kinase Pyruvate KREBS CYCLE
60000000 Myosin mRNA expression 50000000 40000000 30000000 20000000 10000000 0 Strain 1 Strain 2 Strain 3 Strain 4 Selected Trout Strain Families Top Performers Bottom Performers
"Protein sparing effect" Use CHO to spare protein for growth
Glycolysis and Gluconeogenesis
Blood glucose regulation: Adaptive responses Short-term: ENDOCRINE - recruitment of available enzyme "pools" from Lysosomes etc.
However, most studied fish have been shown to be insulin insensitive. So what's the trigger? Amino acids alanine etc.
Long-term: TRANSCRIPTIONAL CONTROL through
response elements (transcriptional factors) enzymes themselves enzyme products enzyme substrates
Glycolysis, Glycogenesis, and Lipogenesis
Blood glucose regulation: Adaptive responses Short-term: utilize as energy (glycolysis) Store what's left (glycogenesis) Long-term: ultize as energy Store what can be stored (glycogenesis and lipogenesis)
Liver Muscle (app. 10x that of liver)
Spill through urine (glucosurea) Glucotoxicity, Lipotoxicity, "Fatty Liver Disease"
Feast and Famine: Who gets what?
Differential Km for hexokinases in brain and elsewhere Hexokinases in the brain are more sensitive enzymes (i.e. active at lower concentrations of glucose) Hexokinase (called glucokinase) in liver is responsive to higher glucose concentrations If this is true for short-term effects is this necessary for long-term adaptation?
Transcriptional Regulation
Yes. We see the same regulation in transcriptional control (i.e. response elements for glucokinase (liver hexokina...