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Smoltification Flashcards

1
Q

Define Anadromicity

A

when an organism migrates up river (from the sea) to spawn

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2
Q

What is the parr-smolt transformation governed by?

A

Endogenous Rhythm and Exogenous cues

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3
Q

What is the parr-smolt transformation?

A

A process where salmon change from a freshwater fish into a seawater fish by changing their physiology, biology, behaviour and biochemistry

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4
Q

What do environmental cues do (in references to p/s)

A

environmental cues cause a biological cascade which causes the endocrine system to influence biological functions.

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5
Q

What are the two environmental cues that trigger the p/s transformation?

A
  1. Photoperiod

2. Temperature

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6
Q

When is the decision to smolt made?

A

In conditions where the photoperiod is decreasing

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7
Q

When is the p/s transformation complete?

A

When the photoperiod starts to increase

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8
Q

What is meant by the term photoperiod?

A

The amount of light available

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9
Q

How does temperature influence the p/s transformation?

A

A higher temp increases the growth rate (within reason - if too high enzymes denature and the fish dies)

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10
Q

Atlantic salmon come up stream to hatch - where they hatch depends on …….?

A

Temperature and Latitude

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11
Q

How long does it take for the eggs to hatch once they have been laid? And what months of the year?

A

70-160 days, from march through june

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12
Q

What is the name for the salmon (once hatched) and just had its first feed?

A

Alevins

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13
Q

They become … over time (before migration but in FW)

A

Parr

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14
Q

Whan do they begin the p/s transformation?

A

in their 2nd year

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15
Q

What is the name for the salmon when they migrate out to SW?

A

Smolt

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16
Q

How long do they stay in SW as smolts for?

A

3 - 5 years

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17
Q

What happens after 3-5 years?

A

They migrate back to FW to spawn

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18
Q

When do the salmonids become sexually mature?

A

During the migration from saltwater back to freshwater

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19
Q

What environmental cue induces the transformation?

A

The photoperiod

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20
Q

What does temperature do (with regards to the transformation)?

A

It is the modulator so it increases or decreases the acceleration of inhibition

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21
Q

What is meant by the ‘Peak of Smoltification’?

A

When the organism can move into saltwater without any problems

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22
Q

What is meant by ‘The Smolt Window’?

A

The time period when the organism is susceptible to increased light (Feb/Mar)

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23
Q

What does the smelt window depend on?

A

Population and Location

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24
Q

The fish need to …….. … …………. …… to …………. to environmental cues

A

Need to be a certain size to respond

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25
When is the size window?
Around August
26
What happens if the parr is too small at the time of the size window?
They will wait another year
27
What do fish farmers use to farm salmon?
They use photoperiod controlled smoltification
28
What does this controlled photoperiod smoltification cause?
out of season smoltification
29
What happens in the hatcheries?
They expose the newly hatched fish to 24hour sunlight and excess food for growth
30
How much is the growth rate increased compared to the wild in fish farming?
double the growth rate
31
By increasing the growth rate in fish farming what happens?
it means the fish smelt early on
32
Phototreatment is initiated to simulate winter- how long is this simulation and what are the hours of light vs dark?
6 weeks - 18 hours of dark and then 6 hours of light
33
Phototreatment is initiated to simulate spring- how long is this simulation and what are the hours of light vs dark?
6 weeks - 6 hours or dark and 18hoursof light
34
When does the winter period start and finish?
Sept - Oct
35
When does the spring period start and finish?
Oct - Nov
36
What happens at the end of November (in fish farming)?
The salmon are now smolts and can be transferred into SW
37
How does the transformation begin (with reference to endocrine)
Endocrine system senses environmental cues and changes start
38
What do receptors trigger in the endocrine system?
Receptors trigger T3 and T4 thyroid hormones, Cortisol, growth hormone, ICF-1 all to increase and trigger prolactin to decrease
39
What is the main endocrine tissue and where is it located?
The pituitary gland is located just outside the blood-brain barrier
40
What is the main endocrine tissue controlled by?
The hypothalamus
41
The hypothalamus connects with nerves and releases into...?
the posterior pituitary
42
What happens in the posterior pituitary?
signalling molecules are secreted into the bloodstream; Neuroendocrine secretion of hormones via the posterior pituitary via hypothalamus
43
What type of secretion occurs in the posterior pituitary?
neuroendocrine secretion
44
What type of secretion occurs in the anterior pituitary?
Hormone secretion
45
What happens in the anterior pituitary
controlled release of inhabitation of the hormones into the blood stream
46
What do endocrine tissues in the pituitary release?
growth hormone, thyroid hormone, corticotropin, gonadotropin, prolactin
47
What is GHRH
Growth hormone releasing hormone
48
What is TRH
Thyroid releasing hormone
49
What is CRH
Corticotropin releasing hormone
50
What is GRH
gonadotropin releasing hormone
51
What is GHIH
Growth hormone inhibiting hormone
52
What is PIH
Prolactin inhibiting hormone
53
What does the hypo-pituitary GH (IGF-1) affect?
Growth and SW tolerance
54
What does the hep-pituitary interrenal axes affect?
SW tolerance by stimulating physiological changes
55
What does the hypo-pituitary thyroid do?
The hypothalamus contains TRH which is released and stimulates the anterior pituitary to release TSH (thyroid stimulating hormone)
56
What does TSH do?
stimulates the production of T3 and T4
57
What is T3 used for?
The metabolism
58
What is T4 used for?
Growth
59
What chemical do T3 and T4 depend on?
Iodine
60
What does NIS stand for?
Na+ Iodine symporter
61
What does NIS do?
Transport Iodine into the epithelial cells (lining the colloid) where it is oxidised (from -ve to +ve Iodine) and moved into the colloid
62
Where is the +ve iodine stored?
In the colloid located in the thyroid globulin (T4) until needed
63
What happens when thyroid hormones are needed?
Iodine is arranges into T3 or T4 and secreted into the blood
64
Which of the thyroid hormones is secreted the most?
T4
65
T3 has a ...... ....... to receptors on target tissues and thus higher ...........
higher affinity | biological activity
66
When T4 circulates in the blood stream, what happens in the cells?
It is de-ionized to T3 which is more biologically active
67
How is thyroglobulin synthesised and what does it contain?
thyroglobulin is synthesises by thyroid epithelial cells and contains tyrosines
68
How is Iodine transported into the lumen of the follicle?
by NIS
69
What does thyroid peroxide do?
Thyroid peroxide catalyses the iodination of tyrosines on thyroglobulin and also catalyses the synthesis of thyroxine or triodothryonine from two iodotryosines
70
What does cathepsin beta do?
Hydrolyses thyroglobulin into thyroxine and triiodothyronine that enters the blood
71
Where is T4 produced?
In follicles
72
T3 and T4 bind to the same receptors, true or false?
True
73
What happens to T4 once it is in the peripheral tissues?
it is converted to T3
74
What changes in behaviour do salmonids have when p/s transformation occurs?
They go from aggressive to schooling behaviour, and begin to rise from the gravel
75
when p/s transformation occurs why does their swim bladder increase?
They will be swimming more and need it for bouyancy
76
What changes in appearance do salmonids have when p/s transformation occurs?
they become silver and change shape to become slim and thin, losing their parr markings
77
When the p/s transformation occurs there is a change in rheotaxis; what does this mean
This means that they start to seek out light and rise towards it.
78
What changes in growth do salmonids have when p/s transformation occurs?
Increased growth faster length growth lower condition factor
79
What is the equation for the condition factor?
weight/lenght
80
How do the parr increase their SW tolerance to become a smolt
Decrease # FW chloride cells | Increase # SW chloride cells
81
How do the parr decrease the number of FW chloride cells/increase the number of SW chloride cells?
Use NKA isoform alpha 1A to decrease FW | Use NKA isoform alpha 1B to increase SW
82
Explain how the intestinal cell changes in the p/s transformation
- Na+K+ATPase creates Na+ gradient - Na+ gradient drives the NKCC citrons to absorb K and 2Cl- - Cl- goes out via chloride channels - intestinal water uptake increases - Na+K+ATPase increases intestinal permeability as salt water drinking begins
83
Why as a smolts is there decreased urinary production?
they are now hypo osmotic to their environment and so lose water so less urine production
84
Intestinal absorption of water occurs mainly through the ......... route but the .......... route is also possible
paracellular | transcellular
85
What do aquaporins do?
they increase the permeability across the phospholipid bilayer (essentially water channels)

Marine Lifecycles (3 decks)

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