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Reproductive Biotech
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Superovulation treatment of the female with hormones so that more eggs are ovulated than normal
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Superovulation alter normal level of FSH Follicle Stimulating Hormone
Typical results are ovulation of 10 or more eggs
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Superovulation recipient animals must be closely synchronized with the donor cow. Must be at the same stage in their heat cycle
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EmbryoTransfer provides opportunity to introduce genetic material into populations of livestock while greatly reducing risk of transmission of diseases
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ET Process super ovulate donor cow synchronize recipients
breed donor cow (A.I.) when in heat
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ET Process flush - remove fertilized eggs from donor before 7 days gestation plant embryo in the recipient animal
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Transfer to recip. Non surgical common
deposit embryo in uterus through cervix with AI straw and gun
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non surgical usually 70-80% success rate
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Surgical incision in recip through flank
tip of uterine horn is exposed cut open and embryo is deposited
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Surgical recip is sewn shut less than 60-65% success rate.
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ET now allows for shipping of 500 registered holsteins in four sealed flasks in one seat on an airplane
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Splitting Embryos remove embryo from cow 7 days after conception
collect unfertilized egg and cut into zona pellucida
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Splitting Embryos remove contents of unfertilized egg leaving the zona intact similarly, cut into zona around embryo
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Splitting Embryos divide cells in embryo in half using a micro surgical blade remove 1/2 of the cells and transfer them into empty zona
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Splitting Embryos seal zona with microjolt
each 1/2 put into recipient animals
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Cloning 6 days after conception, 32 cell embryo is removed from donor cow recipient egg cell is taken from a slaughterhouse
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Cloning recipient cells DNA is removed
one of the 32 cells is removed from the embryo
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Cloning the single cell is inserted into recipient egg
recipient cell is given a microjolt - fuses grafted DNA to plasma membrane
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Cloning desired embryo will replace cells that are removed providing a continuing supply of DNA to be inserted into more recipient cells
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Cloning resulting offspring are cloned identical siblings
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Sexing Embryos usually done by determining if embryo is a male
males have Y chromosome H-Y antigen can be detected in male cells
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Detection of Y break open cells and stain chromosomes to identify presence of Y chromosome Karyotyping must examine at least 10 cells
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Detection of Y 70% accurate use Y specific probe for ID
Y specific probe attaches to Y chromosome
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Detection of Y can be detected by radioactivity or special light
85% accurate
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H-Y Antigen make an antibody by injecting H-Y antigen into mice
attach dye onto the antibody for easy detection of male embryo
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H-Y Antigen add antibody to embryo and if embryo is male it will glow
if it is female it will remain dark
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Advantages does not kill cell no damage to embryo
fast - can be few hours or less than one hour old
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Disadvantages need high skilled technician 80% accurate
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Freezing Embryos cooling embryos -5C or 40 F
can be stored several days freezing -196 C or -320 F must cool before freezing
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Freezing Embryos slowly cooled to -25C at a rate of .5C per minute and then plunged into liquid Nitrogen
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Freezing cryoprotectants are used to lower the freezing point so removal of water can be increased
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Freezing Cryoprotectant used in cattle - glycerol
also help prevent cell membrane from becoming brittle dilutes salt in cell
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Thawing 500 C per minute complete is about 20 seconds
glycerol is removed and embryo is placed in successive solutions
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Thawing glycerol is removed and embryo is placed in successive solutions to re hydrate
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Thawing if done too slowly embryo will burst because large ice crystals will form 70-80% success rate
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Animals Genetic Transformation two tools embryo micromanipultion
recombinant DNA technology
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Genetic Trans. Occurs when new genetic info is introduced into animals genome
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Methods ES - Embryonic Stem EC - Embryonic Carcinoma cells
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ES or EC cells harboring the foreign gene are incorporated into blastocyst resulting in a mosaic animal
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EC potential for tumor formation
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Retrovirus infection retro. Carrying desired gene is used to transformhost close to 100% efficient
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Microinjection of several hundred copies of DNA are injected into male pronucleus of one or two cell embryos
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Microinjection inefficient mice - 10-15% are born
only 25% express new trait
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Screening is it transgenic? Incorporation of gene expression of gene
germline incorporation
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Agricultural Use rabbit sheep pig cow
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The End !! :)
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