pre-midterm Flashcards
which species have no ovulation and spawning in captivity?
black cod, halibut, sturgeon
which species have poor spermatogenesis?
pike
which species have excessive spawning?
tilapia, sunfish
what are the 7 reasons for sex manipulation? **
- no ovulation and spawning in captivity
- poor spermatogenesis
- excessive spawing
- seasonal spawning
- asynchronous spawning
- sex differentiation
- growth vs reproduction (SEE GRAPH)
what are the 8 stages of Meiosis (describe)
Prophase 1: reduction Metaphase 1: division Anaphase 1: 2n becomes 1n Telophase 1: 1st pb lost. vitellogenesis P2: gvbd M2: ovulation A2: 2nd polar body begin separate/shocked T2: 2nd polar separtates/absorbed
Explain Prophase 1
- initiation of GONADAL MATURATION
- beginning of RECRUDESCENCE
- meiosis stops and vitellogenesis starts
- vitellogenin deposited and present in blood
- longest stop in meiosis. longer in big eggs
- meiosis may become permanently arrested at the end of vitellogenesis
Explain Prophase 2
- should start after telophase 1, may not
- GV usually migrates to side of egg
- GV disappears (GVBD germinal vesicle break down)
- signals ovulation
what is another term for GVBD?
FOM (final oocyte maturation)
What kind of chromosomes do progeny have after androgenesis?
50% XX females and 50% YY supermales
how can you wind up with a stock of all YY supermales without going thru androgenesis?
Breed YY males with YY females.
how do you obtain YY females?
estrogen-treat the fry
what is Aneuploid
mistakes. the shocking wasnt done at the proper time, and a fish can have both diploid and tetraploid cells in their body
To create triploids, at what stage do you shock the eggs? what happens with the egg that creates triploidy?
anaphase II. The second polar body is retained.
2 methods of triploiding fish
- shocking normal eggs
- breed 4n fish with 2n fish
how can you differenciate a 3n RBT from a 2n?
size. RBT nuclei 50% larger than 2n
what egg development process does triploiding interrupt?
meiosis
when do you shock an egg to get tetraploids?
1st cleavage
are both male and female 4n fertile?
yes
how do you create clones?
apply mitotic gynogenesis. raise fry, breed. Then apply mitotic or meiotic gynogenesis.
recrudescence
egg maturation
what is oogenesis?
development of oogonia to mature egg
For an oogonia in an ovarian follicle, what are the walls formed from? what do they produce?
walls formed by thecal and granulosa cells, produce estrogen
What is the best physical indicator for when maturation will occur, and give examples of when this might not be a true rule.
size usually determines when maturation occurs.
- some fast growing fish may not mature at expected size.
- some slow growing fish may mature at small sizes and old age
Endovitellogenesis
ovary produces yolk globules, secrete mucopolysaccharieds into the perivitelline space. Set up osmotic gradient that draws in water and egg activates
Vitellogenesis:
deposition of nutrients and lipids in yolk. (?? double check with some one else’s notes). September 18
Exogenous Vitellogenesis
liver main source of vitellogenin and lipid. secreted due to effect of estrogen. lipids apprear as small droplets, clear. can be colored. 1st sign of egg development. Later droplet coalesce (join together). rate may predict ovulation
FOM. what does it stand for, and what stages occur with FOM
final oocyte maturation
- immediately preceeds ovulation
- fusion of lipid droplets into 1. few large droplets.
- GV oves to edge of egg (where micopile is)
- GVBD.
- egg hydrates. physical increase in size of egg
- microvillae break and egg is loose in follicle.
- eggs may be expressed.
which four ways can you obtain eggs for ovulation prediction?
i) sacrifice brood and dissect
ii) surgically remove eggs and suture
iii) catheterize female and suck or squeeze eggs out
iv) hand stripping
what fluids should eggs be examined in?
ovarian fluid, artificial ovarian fluid (stockard solution)
What 6 things should you examine eggs for predicting ovulation
i) appearance of lipid droplets
ii) lipid droplets enlarge
iii) lipid movement to the pole of the egg
iv) germinal vesicle migration
v) GVBD
vi) hydration
What are some signs of maturation other than observing eggs? (4)
i) tail wagging
ii) morphological changes; urogenital papillae, intense coloration
iii) secondary sexual characteristics
iv) nest building, aggression
Atresia:
blockage of oviducts by eggs
eggs may be resorbed or female may die
What are the 3 patterns of oogenesis, and briefly describe
i) Synchronous.
- all oocytes at same development stage.
- typical of semelparous, iteroparous fish that spawn 1/year.
ii) Group synchronous
- 2 or 3 all at same stage.
- 1 group of ripe eggs, 2nd group at a lesser stage.
- iteroparous fish that spawn 1-2/year
iii) Asynchronous.
- oocyte in all stages
- a fish that spawns many times per year
Environmental cues for maturation/breeding. 3 major 3 minor
major:
-temperature
-photoperiod
-nutrition
minor:
-water quality/volume
-social interaction
-suitable substrate
Fish sensors (5)
- eyes
- pineal gland
- metabolic sensors sense nutritional state
- temperature receptors
- olfaction
Hypothalamus. what is it, what does it do. (4 points)
- releasing hormones
- inhibitory factors
- nor-epinephrine
- serotonin
Pituitary
- 2 types of GTH
- complimentary hormones
Ovaries and testes (what sex steroids does it have?)
17B estradiol (females) 11 ketotestosterone (male and female)
Soma
secondary sexual traits
spawning behavior
2 ways of manipulating the spawning cycle (graph thing)
i) environmental cue
- receptor>brain>hypothalamus axis.
ii) hormonal
- hypothalamus>pituitary>ovarian axis
why are environmental cues important?
- feeding: affects circadian. rhythm of GTH circulation.
- nutrients for vitellogenesis
- conditioning spawners
What is ‘photoperiod’?
- primary cueing mechanism for temperate species.
- rate of change and direction of change
- may not be important for tropical species.
how is temperature important in relation to spawning?
- tropical species, important cue
- N and S edge of range temperature can control spawning
- tilapia breed constantly if above 28*C
- tilapia dont breed under 22*C
- sudden temperature change can stimulate spawning
Pheramones
metabolic byproducts of sex steroids
Pineal Gland
- produces melatonin, secretes at night not during day
- melatonin acts as a transducer of photoperiod
Hypothalmic Releasing Hormone
- GTHRH
- GnRH (gonadotropin)
- GnRF (gonadotropin releasing factor)
- LHRH (human lutenizing hormone releasing hormone
- LHRHa (human lutenizing hormone releasing hormone analogue) ** most commonly used
- SGNRHa- Salmon Goadotropin releasing hormone analogue
GTHRH - what does it stand for, where is it concentrated?
Gonatropic hormone releasing hormone
-hypothalamus, olfactory and optic centre of brain
LHRHa- what does it do?
- most likely hormone to induce fish to spawn
- cause fish to secrete own GTH, which tend to be spp. specific
- simple 10 amino acid molecules - cheap
- low species specificity
- small molecules = no immune response
- use ug amounts vs mg for induction. cheap
how much stronger is analogue than natural GTHRH?
3x
how many injections should be done when using GTHRH?
<2 , 1/4 dose for 1st (priming),
3/4 dose for 2nd (resolving)
GTHRHIF
GTHRH inhibitory factor
- dopamine
- dopamine effect inhibited by Pimozide, Domperidone
Best way to inject GTHRH?
- best intraperitoneal
- 2nd best intramuscular or dorsal sinus
how would you release GTHRH slowly?
- mix LHRHa w cellulose or cholesterol
- coconut oil
- polymers
- ovaplant
Name 5 Gonadotropins
- GTH (gonadotropin hormone)
- GnH (gonadotropin)
- Pituitary extracts
- FSH Folicle stimulating hormone
- HCG Human chorionic gonadotropin
which 2 Gonadotropins are human?
- FSH folicle stimulating hormone
- HCG Human chorionic gonadotropin
what are the 2 GTH in fish?
GTH 1: Glycoprotein. big molecule. controls most reproductive changes via gonads stimulated to release sex steroids.
-GTH 2: causes incoporation of nutrients into oocyte
GTH has circadian rhythem. what is this?
controlled by time of day and time fed. (diagram)
3 forms of GTH.
Pit extract -acetone dried -ethanol preserved -freeze dried Partially purifies pit extract -SG100 -doesnt work as well HCG+LH -usually 2 injections -1/4 1st, 3/4 2nd dose -sometimes successive small doses (4-6)
3 types of sex steroids
- 17B estradiol
- 11 ketotestosterone
- 17+20B Dihydroprogesterone
what is 17+20BDHP?
17+20 Dihydroprogesterone. sex steroid
what are sex steroids secreted by?
testes and ovaries
what cells produce testosterone in general? what cells produce testosterone in testes?
thecal cells, lydeg cells
what changes testosterone to estrogen?
granulosa
what happens to 17B steroid when the fish is very near ovulation?
decreases suddenly, occurs with elevated testosterone.
tamoxifen clomophone citrate
counteracting negative feedback, it blocks estrogen. Effects and elevates GTH production
sex determination is generally under _______ control.
genetic
what are some important influences on sex manipulation?
environmental and autosomal
3 methods for sex manipulation
- interspecific hybrids
- hormones
- chromosome manipulation
objectives for sex manipulation
- monosex population
- sterile poplulation
with a 100% pure brood, what are two combination of tilapia you can breed to produce 100% males?
O. niloticus female with O. aureus male
O. niloticus female with O. hornorus male
Steroid treatment: two basic, general rules
- use testosterone to get males and estrogen to get females
- must apply before sex differentiation
2 most common treatments for steroids?
- bath @ 50% hatch and 50% swim-up
- feed testosterone - 10-21 day
- bath 200ppm testosterone - 2 hours (can use estrogen to feminize)
- food 25mg/kg food
what happens if you have too high or too low of a dosage of steroids?
-sterile fish that dont grow and hermaphrodites
LOOK AT YY XX XY BREEDING MONOSEXING
pg 14
how do you do hormone sterilization?
use high dose of testosterone
- 20-40mg/L bath -50% swimup and hatch
- 200-400mg/kg food for 1st 3 weeks feeding
