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Fish Reproduction Brian Peterson, M'S'

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Fish Farming vs Cattle Ranching ... FISH--Male/female development is ... individuals develop first into females and turn later into males-Ex (Clown Fish) ... – PowerPoint PPT presentation

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Title: Fish Reproduction Brian Peterson, M'S'


1
Fish Reproduction Brian Peterson, M.S.
2
Objectives
  • Aquaculture and its role in the U.S. and Idaho
  • Female reproductive system
  • -Ovary and follicle anatomy
  • Sex determination and hermaphorditism
  • Alligator production in Idaho
  • Research at the U of I

3
1999 Census Catches 1 Billion in Sales
  • Aquacrop Value ()
  • Catfish 488,000,000
  • Trout 77,000,000
  • Salmon 100,000,000
  • Ornamental 69,000,000
  • Source Economic Research Service, USDA

4
Fish Farming vs Cattle Ranching
  • Fish farming is the fastest growing sector of the
    world food economy.
  • -Growing 11/year
  • -13 million tons produced in 1990 to 34.4
    million tons in 1999.
  • Cattle ranching hit high of 53 million tons in
    1990.
  • -Surpass cattle ranching as a food source by the
    end of this decade.

Source World Catch News
5
Rainbow Trout Production 1999
  • Idaho currently ranks 1 in the nation in RBT
    production- 48 of total sales
  • 76 of market size fish
  • 2)North Carolina 4.5 million lbs
  • 3)California 2.3 million lbs
  • 1999 Idaho produced 47.5 million fish which
    equates to 46 million lbs
  • 1999 total sales of RBT- 37 million
  • Source Economic Research Service, USDA

6
Terms to Know
  • TeleostFish that exclude jawless fish,
    cartilaginous fish, lobe-finned fish, and
    sturgeon.
  • VitellogeninGlycolipoprotein produced in the
    liver and accumulated in the oocyte as yolk.
  • VitellogenesisProcess of yolk formation.

7
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8
Female Reproductive System
  • Hypothalamus, pituitary, ovary, and liver.
  • In all species, oogonia proliferate in the
    ovary, become oocytes, undergo vitellogenesis,
    maturation, and ovulation.
  • Endocrine controls of the system begin with
  • 1.) hypothalmic responses to environmental cues
  • photoperiod and temperature

9
Female Reproductive System
  • 2.) hypothalmic responses to proximal cues like
    substrate type, courtship behaviors, and
    pheromones.
  • Ultimately these cues influence gonadotropin
    releasing hormone (GnRH) that stimulates GTH-I
    and GTH-II.

10
Role of GTH-I and GTH-II
  • Ovarian and testicular function is controlled by
    GTH-I and GTH-II (glycoprotein heterodimers).
  • GTH-I/GTH-II contain a common alpha subunit and a
    distinct beta subunit conceived to be FSH-and
    LH-like.
  • GTH-I important for vitellogenesis, early
    gonadal development, and elicits the production
    and storage of GTH-II.
  • GTH-I secreted during the early phases of
    ovarian development.

11
Role of GTH-II and GnRH
  • GTH-II stimulates events leading to final
    oocyte maturation and ovulation in females and
    spermiation in males.
  • GTH-IIstimulated by GnRH, NE, and NPY
  • inhibited by DA
  • In teleosts, multiple GnRH molecules may be
    expressed simultaneously with different
    functions.
  • GnRH mRNA levels can be influenced by many
    factors state of sexual maturation,
    photoperiod, and sex steroids.
  • Indicates that GnRH is controlled by internal and
    external factors.

12
Delivery of hypothalmic hormones
  • How is GnRH delivered to the gonadotrophs in the
    pituitary gland?
  • In mammals a hypothalamohypophysial portal system
    is present.
  • In cartilaginous, salmonid fishes, and others no
    portal system exists. GnRH delivered by direct
    innervation of all portions of the pituitary.

13
Changes in levels of GTH-I and GTH-II in coho
salmon during reproductive maturation
GTH-II
GTH
GTH-I
M
O
N
A
A
M
S
J
J
Vitellogenesis Ovulation
Adapted from Dickoff and Swanson, 1990
14
Ovary Anatomy
  • Teleost ovarian structure is classified into two
    forms gymnovarian and cystovarian
  • Gymnovarian ovaries are possessed by most bony
    fishes except (salmonids).
  • Lack a true ovarian cavity.
  • Characterized by ovigerous folds which lie
    exposed to the peritoneal cavity.
  • Oocytes are ovulated into the coelom and moved
    into the oviduct by ciliated epithelium.

15
Ovary Anatomy
  • Cystovarian ovaries (salmonids) have a true
    ovarian capsule.
  • Oocytes are ovulated into the intraovarian space
    and move down to the cloaca without entering the
    peritoneal cavity by ciliated epithelium or
    smooth muscles.

16
A section through a cystovarian ovary showing
ovigerous folds and location of oocytes
Adapted from Turner, 1983
17
Gymnovarian
Cystovarian
Bilobed
Bilobed
Mesonephric Kidneys
Mesonephric Kidneys
18
Follicle Anatomy
  • Ovarian follicle consists of a developing oocyte
    and two surrounding cells layers.
  • Innermost layer steroidogenic granulosa cells
    Outer layer thecal layer (fibroblasts, collagen
    fibers, capillaries, and steroidogen special
    theca cells).

19
Diagrammatic representation of the follicle and
oocyte during early vitellogenesis
Nagahama, 1983
20
Oocyte Recruitment
  • Three modes of oocyte development in teleosts
  • Synchronous- all oocytes develop synchronously
    and ovulate at the same time.
    Ex Pacific Salmon (semelparous)
  • Group-synchronous- vitellogenic oocytes are
    divided into groups, which ovulate over the
    course of one breeding season.
  • Ex RBT (iteroparous)

21
Oocyte Recruitment
  • Three modes of oocyte development in teleosts
  • Asynchronous- oocytes at all developmental stages
    are present in the ovary.
  • Ex Tropical fish

22
Mechanisms of Sex Determination
  • I. Recombination of sex chromosomes at
    fertilization
  • a. Chromosomal genotype
  • Mammals and most fish Male XY
  • FemaleXX
  • Birds and some fish MaleZZ
  • FemaleZW

23
Sex Determination/Development
  • b. H-Y Antigen
  • 1. Male specific antigen present on the
    surfaces of cells
  • XYH-Y antigen
  • Old theory suggested H-Y antigen existed in
    fish--Not true
  • 2. Can be used to sex embryos in mammals
  • 3. Does not cause male development

24
Sex Determination/Development
  • SRY Gene
  • Located on the Y chromosome of mammals and NOT
    FISH
  • Stimulates male development
  • Produces Testis Determining Factor (TDF)
  • FISH--Male/female development is regulated by
    genetic and hormonal control

25
Sex Determination/Development
  • Development of the gonads, reproductive tract and
    external phenotype
  • a. Origin of gonads
  • Fish are similar to mammals in that the male and
    female start with an undifferentiated gonad
  • Mesonephros (Primative kidney)
  • Ovary and testis arise from this undifferentiated
    gonad-PGC migrate from yolk sac to the genital
    ridge--Mechanism is unclear in fish

26
Sex Determination/Development
  • b) Origin of reproductive tract
  • Two duct system
  • Mullerian ducts--female reproductive
    tract-oviducts, uterus, cervix and vagina
  • Wolffian ducts--male reproductive
    tract-epididymis, vas deferens, seminal vessicles
  • FISH--tubular extension of the gonad

27
Mechanisms of Sex Determination
  • II. Temperature-dependent sex determination
  • Alligators and turtles have no heteromorphic pair
    of chromosomes-sex is determined by temperature
  • Example-Alligators-lays 40-45 eggs (65 days to
    hatch)
  • 93oF-All F
  • 86oF-All M
  • 88oF-Half F and half M

28
Alligator Production
  • Alligators are being grown in southern ID
  • Young alligators are grown in tanks at 85-90oF
    year- around-grow at a rate of 2 inches per month
  • Alligators are harvested at 3 yrs old (5 feet
    long)
  • Skins sold for 30/ft
  • Meat sold for10-20/lb

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32
Mechanisms of Sex Determination
  • III. Behavior sex determination
  • Social situations can initiate changes in gonadal
    sex.
  • Example-(Marine fish) Sex change is initiated by
    removal or addition of dominant male or female to
    a population.
  • Mechanism of action is unclear!
  • However, GnRH-cells in the preoptic area of the
    brain increase.

33
Hermaphroditism in Fish
  • c. Three forms of hermaphroditism in fish
  • 1. Protogynous hermaphroditism-individuals
    develop first into females and turn later into
    males-Ex (Clown Fish)
  • 2. Protandrous hermaphroditism- individuals
    develop first into males and turn later into
    females
  • -Marine fish

34
Hermaphroditism in Fish
  • 3. Synchronous hermaphroditism-Both male and
    female states coexist functionally
  • -Sea bass (self fertilization)

35
Research at University of Idaho

Hypothalamus
SS (-)
GHRH ()
Anterior Pituitary
GH
36
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37
My Research
  • Release patterns of GH in fish.
  • Somatostatin role in GH release.
  • Passive immunization against SS
  • Immunize another animal (rabbit, sheep, cow)
  • Active immunization against SS
  • Immunize animal of interest

38
GH values over time in RBT
39
RBT injected with SS-14 (5 ng/g BW)
40
RBT passively immunized against SS-14 (125)
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