480 likes | 710 Views
Biotechnology: Status and Uses. Animal Science 434 John J. Parrish. Reproductive Biotechnology's. Artificial insemination In vitro embryo production In vivo embryo production Embryo transfer Gender selection Genetic engineering Cloning. In Vitro Production of Embryos.
E N D
Biotechnology: Status and Uses Animal Science 434 John J. Parrish
Reproductive Biotechnology's • Artificial insemination • In vitro embryo production • In vivo embryo production • Embryo transfer • Gender selection • Genetic engineering • Cloning
In Vitro Production of Embryos • Oocyte isolation and maturation • Sperm preparation • Sperm capacitation • Fertilization • Embryo Development
Searching Isolation
Culture 24 Hours Incubation • Maturation Medium • Tyrode’s • FSH, LH, Estradiol • Fetal Calf Serum 39°C, 5% CO2 in Air
Cumulus Expansion Unexpanded Expanded
Sperm Preparation Semen 45% Percoll 90% Percoll
Embryo Development 2-Cell 4-Cell 8-Cell Morula
Embryo Development Blastocyst
In Vivo Embryo Production • Normal cycling female • horses • Superovulated female • Cattle • Sheep • Goats • Deer • Humans
PGF2a eCG orFSH Multiple Ovulations Estrus Estrus Progesterone From C.L. First Follicular Wave 10-12 Stimulating Follicular Development Multiple Ovulations eCGorFSH Ovulation Estrus Estrus Progesterone From C.L. 17
Stimulating Follicular Development • eCG (PMSG) • Single injection • FSH • 8 injections • AM/PM • Decreasing doses
Day 0 eCG Day 2 AM/PM PGF2a Estrus Day 3.5 to 5 Stimulating Follicular Development AI at 12 and 24 hr after coming into estrus
Day 0-3.5 FSH AM/PM (8 injections) Estrus Day 3.5 to 5 Day 2 AM/PM PGF2a Stimulating Follicular Development AI at 12 and 24 hr after coming into estrus
Embryo Recovery • Early to mid blastocyst • Day 6 to 7 (estrus, breeding = day 0) • Flush uterus • Surgical • Nonsurgical
Stage of Embryo at Recovery Tight Morula (day 5 - 7) Early Blastocyst (day 7 - 8) Blastocyst (day 7 - 9)
Embryo Transfer • Recipient must be synchronized with donor or 1 day behind • Surgical • Flank • Nonsurgical • Similar to AI but going through diestrus cervix
Success (pregnancy rate) • In vivo embryos • Fresh (60%) • Frozen (50%) • In Vitro embryos • Fresh (40 - 50%, sometimes 60% if transfer 2 embryos) • Frozen (30 - 40%)
Embryo Transfer Uses • Introduction of new genetics • Import/Export • Twinning • Coupling with other biotechnologies
Embryo Sexing • Hy Antigen • Associated with male cells • PCR and Detection of Y and X DNA
Octopus Springs - Yellowstone National Park Home of Thermus aquaticus - Taq Polymerase
PCR Approach to Embryo Sexing Y X F M F F F F F F
Sperm Gender Selection Selection of X or Y sperm
PERCENT DNA DIFFERENCES BETWEEN X and Y CHROMOSOME Human 2.9 Cattle 3.8 Chinchilla 7.5 Turkey 0 X Chromosome has more DNA!!!
Flow Cytometer Separation of X and Y Sperm Sperm Stained With DNA Sensitive Fluorescent Dye 9 0° 0° L A S E R - + + - Y s o r t X s o r t
Sperm Gender Selection • Flow Cytometry • Only method that works! • Very few sperm recovered • Currently not suitable for AI use • Will be expensive and has reduced fertility
Fetal Sexing OR Ultrasound Evaluation • Day 55 - 65
Cloning Split morula
Cloning by Nuclear Transfer Cycles are limited Only 3 - 4 cycles
Cloning Uses • Production of identicals • Agricultural uses • Transgenics • Stem cell production and research
Gene Transfer Using Micro-Injection of Pronuclei Less than 1% efficiency
Gene Transfer Using Viral Transfection Better success but left with potential for viral replication
Problems with Gene Transfer • Problem • Need to control site of gene insertion • Need to control number of gene copies inserted • Solution • Do genetic manipulation on cells in culture • Select correct cells for nuclear transfer and cloning
Potential Uses of Genetic Manipulation • Production of spare body parts • Disease resistance • Increased production traits
Dairy Production in the Tropics • The F1 - Holstein X Native Cow best in milk production • Any cross to get F2 is not as good as F1 • Potential in vitro embryo production • Import Holstein oocytes from US • Use native semen • Produce F1 cross embryo and implant in an F1 cow