biotechnology and animal breeding Flashcards
what is biotechnology broadly defined as?
applying biological knowledge to practical needs/problems
what are the two animal breeding perspectives?
reproductive technologies(species level) and molecular technologies(genetic level)
what are the five types of reproductive technologies?
- AI
- estrus synchronization
- embryo transfer
- sex control (determining the sex of the embryo)
- cloning (asexual repro)
what are the three types of molecular technologies?
- DNA fingerprinting
- marker assisted selection
- gene transfer
what does the extent of impact of biotechnology in animal breeding depend on? (4)
- effectiveness
- practicality
- cost
- public perception
what is artificial insemination?
semen is collected from males and then used fresh, cooled, or frozen to breed females
why isn’t artificial insemination always easy or practical? (3)
- females need to be in heat
- additional cost of moving to breeding area
- properly inseminated at the correct time with ovulation
what are the three hormones used in estrus synchronization?
- PGF2a
- progestogen
- GnRH
what is estrus synchronization?
when hormones are used to induce females to come into heat at the same time
what is the benefit of estrus synchronization?
reduces number of days to inseminate
what is PGF2a? what does it cause?
(prostaglandin) hormone used in estrus synchronization; it causes regression of the corpus luteum and a decrease in progesterone synthesis
what does progestogen cause?
negative feedback on the hypothalamus by blocking LH (luteinizing hormone) and FSH (follicle stimulating hormone)
What does GnRH stand for? what does it cause?
gonadotropin releasing hormone; causes ovulation/luteinization of a growing follicle
what are the steps of embryo transfer?
- donor is superovulated
- donor is inseminated
- after an interval of time, embryos are transferred to recipients or frozen
what is embryo transfer?
collection of embryos from donor females and transferring them to recipient females
what does the surrogate mother provide in ET?
the environment for the embryo
what does the donor mother provide in ET?
genetics
what is the advantage of embryo transfer?
allows females to have many more offspring than normal
what are difficulties in embryo transfer?
- identifying candidates
- certain problems for genetic evaluation (traits with maternal effects; recipes are usually not high quality)
- more costly and difficult than AI
- must synchronize donor and recipes if using fresh embryos
what is to the female as AI is to the male?
Embryo Transfer
what is more costly and difficult: AI or ET?
ET
what are the nine steps of embryo transfer?
- superovulation of donor with gonadotropins
- artificial insemination (5 days after initiating superovuation)
- non-surgical recovery of embryos
- foley catheter for recovery of embryos
- isolation and classification of embryos
- storage of embryos indefinitely in liquid nitrogen or at 37 C (room temp) for 1 day
- transfer of embryos to recipients surgically or non-surgically
- pregnancy diagnosis by palpating through the rectal wall 1 to 3 months after embryo transfer
- birth (9 months after embryo transfer)
what does “in vitro” mean?
in a test tube
what does “in vivo” mean?
in live animal
what does “in saco” mean?
in a plastic bag
what is the process of in vitro fertilization?
- eggs are collected from donor female through aspiration of the reproductive tract
- eggs are incubated / matured and fertilized in lab
- eggs are frozen or transferred to recipient
what is a benefit of collecting eggs through aspiration of the repro tract?
you can collect the eggs at any time / don’t have to wait for the animal to mature to collect
what are the two ways to harvest eggs?
- ultrasound guided aspiration
- laparoscopy
during what stages are embryos usually transferred?
the 8-cell stage or blastocyst stage
what are the advantages of in vitro fertilization?
- increased number of possible pregnancies
- collect eggs repeatedly from the same donor at short intervals
- doesn’t have to be a certain stage of the estrous cycle
- there is no need to superovulate the donor females
- decreased generational interval
- eggs can be collected from young, pre-pubertal females
what are the disadvantages of in vitro fertilization?
- expensive
- success rate is relatively low
- abnormalities of offspring
are clones healthy?
yes, they are like any other animal
who is the scientist that cloned dolly?
Ian Wilmut
how is cloning adult animals done?
insert mature, differentiated cells into ovum
- all genes necessary for growth must be there
- somatic cells genes are turned on again to produce different types of tissue
what are some suspected genetic negatives of cloning adult animals?
- age rapidly
- telomeres on chromosomes unravel
why would a cloned animal have different performance?
they would have the same genetic worth but performance would differ due to environment
what are the steps of cloning an ewe (the roslin method)?
- an ewe provides the mammary cell to be cloned
- a mammary cell contains copies of all genes needed to produce a sheep, but only genes for proteins required by mammary cells are active
- cells grow and divide, generating precise copies of themselves. then the cells are deprived of nutrients, inducing them to dormancy. at this stage, all of their genes can be activated
- another (or same) ewe provides the egg
- the egg is preserved in a laboratory dish
- the nucleus is dislodged from the cell
- the mammary cell and the nucleus from the egg blend with a spark of electricity. molecules in the egg then program genes in the mammary cell to engender the embryo
- clusters of embryonic cells are grown
- embryos are implanted into a surrogate mother
- the resulting lamb is a clone of the donor ewe
what is somatic cell nuclear transfer?
a technique for creating ovum with a donor nucleus
when is somatic cell nuclear transfer used?
- embryonic stem cell research
- “therapeutic” cloning
- the first step of reproductive cloning
what are the limitations of SCMT (somatic cell nuclear transfer)?
- places enormous stress on both egg cell and introduced nucleus
- procedure cannot be automated
- biochem is involved in reprogramming differentiated somatic cell nucleus and activating recipient ovum
- not all of donors genetic info is transferred
- clones born from SCNT are not perfect copies
what are some points of controversy regarding cloning?
- human stem cell research uses the same first step that reproductive cloning would
- sourcing of human ova (most common source is ones produced in excess of clinical need during IVF treatment)
what two procedures are used for same sex mating?
those for nuclear transplantation and embryo transfer