BIO484 exam Already Passed
What happens during vitellogenesis and what are its hormonal controls? - =Vitellogenesis is
stimulated by GnRH released by the hypothalamus. Production of GnRH is mediated by several
endogenous and environmental factors (innate biorhythms, nutritional status, as well as seasonal
changes in length of day and temperature). In response to GnRH, FSH and LH are secreted by
the pituitary gland. FSH is taken up by granulosa cells and converted into estrogen (E2), theca
cells take up LH and in response produce androgens (such as testosterone), which are converted
into estrogen in neighboring granulosa cells with help from FSH. Estrogen then stimulates the
liver to produce vitellogenins which travel through the bloodstream to the oocyte which absorbs
and converts vitellogenins into yolk proteins which are stored in yolk granules in the oocyte.
After yolk storing is complete ovulation of the egg(s) take place.
What is the main physiological factor that decides if a flatfish larva is ready to metamorphosize?
- =size
What is the main hormone causing flatfish metamorphosis and what are its effects? - =Thyroid
hormones (TH) are the main driving force as high levels of TH are detected at the climax of
metamorphosis. It is associated with accelerated development of the stomach, influences muscle
gene expression, as well as changes in hemoglobin's capacity to carry oxygen. (Usually T4 in
circulation, which upon reception and catalyzation with the enzyme deiodinase is converted into
T3.)
What is the theoretical aim of the osmolab (hagfish one)? - =Theoretical aim is to illustrate the
differences between osmoregulators and osmoconformers, primarily by showing the effects that
lowered salinities have on them.
What is the experimental design of the osmolab (hagfish one)? (sorry for long answer I copy and
paste from my notes lol) - =Net 4 trout, weigh them, sample blood and gill tissue. Net 4 hagfish,
weigh them, sample blood. Put 2 trout and 2 hagfish in 80% SW and remaining 2 trout and 2
hagfish in 60% salinity for 2 hours. Remove fish from exposure to lowered salinity, weigh and
sample them again.
After completed sampling, an NKA-assay will have been prepared, which measures
disappearance of NADH, this is coupled to activity of NKA. A standard curve of this will be run
for later use and to check enzyme quality. The samples are run in quadruplicates with two of
them containing ouabain (NKA-inhibitor) and two that don't contain ouabain. The difference in
, activity between the ouabain containing and non-ouabain containing samples will become the
total NKA activity in absorbance / (10µl*min). This will be divided by the linear regression of
the NKA standard curve to get NKA activity in nmol ADP used/(10µl*min). To make two
samples with different biomasses comparable, a BCA assay is made to investigate total protein
content of the gill samples, each NKA activity result will be divided by total protein content to
make them comparable.
With the blood samples from all fish, osmolality measurements will be taken with a vapor
pressure osmometer, and ion concentrations will be taken with an electrolyte analyzer.
What are expected results from the osmolab (hagfish one)? - =Trout stay generally the same as
they would regulate osmolality, hagfish would gain weight with decreased salinity, and thus also
have a lowered osmolality (also ion concentrations resembling SW). Trout should have lowered
ATP activity at lower salinity as they don't have to regulate ions as much.
What are advantages and disadvatages of sea-based oyster production? - =Sea-based production
means less control over environmental parameters which can more easily lead to poor production
or harmed production. Lack of control in reproductive cycle leads to few triploid (non-
reproductive, fast growing) oysters, and strains that are disease-resistant. This method does
however offer robustness to the seed produced and requires less resources.
What are the three methods of oyster seed production? - =Sea-based production, spatting ponds,
and land-based hatcheries.
What are spatting ponds and how are they used to produce oyster spat? - =Spatting ponds are big
holes dug in the ground for oyster spat to settle within. Large surface area is beneficial to
maximize wind mixing, which contributes to water oxygenation. Ponds are lined with artificial
material (often butyl rubber) and have an inlet for water at the beginning of the season, and for
water renewal after evaporation. Different practices have different amounts of water exchange.
After larvae have been observed, exchange is stopped. When larvae are observed, collectors or
cultch (weathered mussel shells) are added to the water for larvae to settle on.
How could you boost spatting pond production? - =Adding nutrients to the pond can boost
microalgae production which means more food for oysters.
What are advantages and disadvantages of spatting ponds? - =Inlet water can be filtered to
reduce occurrence of fouling organisms, they are less intensive (less resource demanding)
What happens during vitellogenesis and what are its hormonal controls? - =Vitellogenesis is
stimulated by GnRH released by the hypothalamus. Production of GnRH is mediated by several
endogenous and environmental factors (innate biorhythms, nutritional status, as well as seasonal
changes in length of day and temperature). In response to GnRH, FSH and LH are secreted by
the pituitary gland. FSH is taken up by granulosa cells and converted into estrogen (E2), theca
cells take up LH and in response produce androgens (such as testosterone), which are converted
into estrogen in neighboring granulosa cells with help from FSH. Estrogen then stimulates the
liver to produce vitellogenins which travel through the bloodstream to the oocyte which absorbs
and converts vitellogenins into yolk proteins which are stored in yolk granules in the oocyte.
After yolk storing is complete ovulation of the egg(s) take place.
What is the main physiological factor that decides if a flatfish larva is ready to metamorphosize?
- =size
What is the main hormone causing flatfish metamorphosis and what are its effects? - =Thyroid
hormones (TH) are the main driving force as high levels of TH are detected at the climax of
metamorphosis. It is associated with accelerated development of the stomach, influences muscle
gene expression, as well as changes in hemoglobin's capacity to carry oxygen. (Usually T4 in
circulation, which upon reception and catalyzation with the enzyme deiodinase is converted into
T3.)
What is the theoretical aim of the osmolab (hagfish one)? - =Theoretical aim is to illustrate the
differences between osmoregulators and osmoconformers, primarily by showing the effects that
lowered salinities have on them.
What is the experimental design of the osmolab (hagfish one)? (sorry for long answer I copy and
paste from my notes lol) - =Net 4 trout, weigh them, sample blood and gill tissue. Net 4 hagfish,
weigh them, sample blood. Put 2 trout and 2 hagfish in 80% SW and remaining 2 trout and 2
hagfish in 60% salinity for 2 hours. Remove fish from exposure to lowered salinity, weigh and
sample them again.
After completed sampling, an NKA-assay will have been prepared, which measures
disappearance of NADH, this is coupled to activity of NKA. A standard curve of this will be run
for later use and to check enzyme quality. The samples are run in quadruplicates with two of
them containing ouabain (NKA-inhibitor) and two that don't contain ouabain. The difference in
, activity between the ouabain containing and non-ouabain containing samples will become the
total NKA activity in absorbance / (10µl*min). This will be divided by the linear regression of
the NKA standard curve to get NKA activity in nmol ADP used/(10µl*min). To make two
samples with different biomasses comparable, a BCA assay is made to investigate total protein
content of the gill samples, each NKA activity result will be divided by total protein content to
make them comparable.
With the blood samples from all fish, osmolality measurements will be taken with a vapor
pressure osmometer, and ion concentrations will be taken with an electrolyte analyzer.
What are expected results from the osmolab (hagfish one)? - =Trout stay generally the same as
they would regulate osmolality, hagfish would gain weight with decreased salinity, and thus also
have a lowered osmolality (also ion concentrations resembling SW). Trout should have lowered
ATP activity at lower salinity as they don't have to regulate ions as much.
What are advantages and disadvatages of sea-based oyster production? - =Sea-based production
means less control over environmental parameters which can more easily lead to poor production
or harmed production. Lack of control in reproductive cycle leads to few triploid (non-
reproductive, fast growing) oysters, and strains that are disease-resistant. This method does
however offer robustness to the seed produced and requires less resources.
What are the three methods of oyster seed production? - =Sea-based production, spatting ponds,
and land-based hatcheries.
What are spatting ponds and how are they used to produce oyster spat? - =Spatting ponds are big
holes dug in the ground for oyster spat to settle within. Large surface area is beneficial to
maximize wind mixing, which contributes to water oxygenation. Ponds are lined with artificial
material (often butyl rubber) and have an inlet for water at the beginning of the season, and for
water renewal after evaporation. Different practices have different amounts of water exchange.
After larvae have been observed, exchange is stopped. When larvae are observed, collectors or
cultch (weathered mussel shells) are added to the water for larvae to settle on.
How could you boost spatting pond production? - =Adding nutrients to the pond can boost
microalgae production which means more food for oysters.
What are advantages and disadvantages of spatting ponds? - =Inlet water can be filtered to
reduce occurrence of fouling organisms, they are less intensive (less resource demanding)
