ASCI341 Lab Practicum Final Flashcards
What does a CL feel like when rectally palpating cattle?
Projection coming off of the ovary
What does the antral follicle feel like when rectally palpating cattle?
Fluid-filled, not protruding out
List the methods of reproductive technologies
- Semen sexing
- In vitro production (IVP) of embryos
- Trangenic animal production
- Gene Mapping
- Marker-assisted selection
What are the types of transgenic animal production?
Microinjection
Blastocyte injection of embryonic stem cells
Nuclear transfer / cloning
Spermatogonial germ cell transport
What are the applications for reproductive technologies?
- Propagate superior livestock animals
- Remove or add gene to improve a breed of livestock animals
- Select animals for specific traits very early in life
- Production of proteins which are essential to human life
- Organ transplantation
What is semen sexing?
Sexed semen is characterized by the presence of either X‐ or Y‐chromosome‐bearing sperm, allowing the production of offspring of the desired sex.
What is the main difference between x and y-chromosomes in sexed semen?
Main difference: the x-chromosome has an extra short arm that is absent on the y-chromosome.
Y-bearing chromosome: negative charge
X-bearing chromosome: positive charge
How does sexed semen work?
Pass sperm through a laser that excites vital dye. X-chromosome will light up more because they have more total DNA that will pick up more dye)
As sperm pass through the system individually. It gives sperm charge based on the light given off. It then passes through a magnetic field that separates them.
What is the advantage and disadvantage of semen sexing?
Advantage –> dead sperm pass through, which purifies sperm
Disadvantage –> expensive ($500K - 1 million)
What is the success rate of semen sexing?
95%
What is in vitro fertilization of embryos?
- Mix mature oocytes with sperm
- Develop embryos to specific stage and transplant into live animal
How do you superovulate a donor cow for in vitro embryo fertilization?
- Porcine FSH treatment –> promotes more follicle development
What are the steps of in vitro fertilization?
- Synchronization of recipients with donor
- Superovulation of donor
- Inseminate donor with semen from genetically superior bull
- Recovery and identification of embryos
- Transfer viable embryos into synchronized recipients
What stage of embryo is commonly collected during embryo flushing process?
Usually aiming for compact blastocyst stage (would be located in uterine horn)
What is transvaginal oocyte aspiration?
Newer technology –> long ultrasound probe inserted into the repro tract. Palpate through the rectum and pin the ovary against the vaginal wall. The probe has a needle pushing the needle through the vaginal wall into the ovary. Will be able to aspirate fluid out of follicles that contain eggs/oocytes. Connected to an ultrasound machine that has a targeting vector on it.
What is the advantage of transvaginal oocyte aspiration?
Separate oocytes out and can fertilize with sperm from different males
What is pronuclear injection/microinjection?
Foreign DNA is injected into pronuclei.
The oocyte is reduced to a haploid state; sperm has haploid complementary chromosomes. At this point, we perform a pronuclear injection.
What is syngamy?
Fusion of pronuclei
What order of membranes does the fine polled glass pipette pass through in microinjection?
Zona pellucida –> plasma membrane –> cytoplasm –> pronucleus (zygote)
Is pronuclear injection/microinjection more successful in mice or livestock species? Why?
Mouse = 10% success rate. Much less efficient in livestock.
Mouse embryo –> pronuclei are visible under light microscopy
Livestock embryos –> have much more lipid, so you can’t visualize pronuclei.
What are the advantages and disadvantages of pronuclear injection?
Advantage: if we want to over-express DNA, we can generally do it in one generation
Disadvantage: Gene incorporated into genome RANDOMLY and can cause damage. A lot less efficient, and end up killing a lot in the process.
When does blastocyst injection of embryonic stem cells occur?
It occurs at a much lower stage in the development (days 7-9 of embryo development)
Embryo classified with blastocoel (cells inside zona pellucida)
What do inner cell masses form?
Forms embryo
What do trophoblasts form?
Placenta = houses developing fetus during gestation
What are the steps of blastocyst injection of embryonic stem cells?
- get a donor embryo
- Isolate embryonic stem cells
- Gene targeting
- Transform embryonic stem cells
- Selection of transformed embryonic stem cells
- Isolation of transformed ES cells
- Expand transformed ES cells
- Inject transformed ES cells into recipient embryo (blastocyst)
What is a passage in cell culturing for isolating embryonic stem cells?
Let cells grow until they almost populate the whole plate. Then take a subpopulation of cells and split them up, and let them grow again to fill up another plate and so forth
What is gene targeting?
Add / replace / remove gene
What is homologous gene recombination?
Gene swapped out with an altered sequence
Why do we add antibiotics when doing blastocyst embryonic stem cell transfer?
Add antibiotic resistant –> only vells that have taken up foreign DNA will acquire the antibiotic resistance. Only cells that survive antibiotic tx are the ones with genetic alteration
What is a chimeric animal?
An animal chimera is a single organism composed of two or more different populations of genetically distinct cells originating from different zygotes involved in sexual reproduction.
Comes from greek mythology –> aspects of 2 species (manatar)
Is a chimeric animal crossbred?
Not cross bread. Has purebred parts of each
What is a geep?
Sheep x Goat chimeric animal
Geep x Ewe
Lamb
Geep x Goat
Kids
What percent will be purebred Duroc when mixing male chimera with duroc female?
20%
1/5 of the time
What is the advantage and disadvantage of blastocyst injection of embryonic stem cells?
Advantage: Better efficiency than pronuclear injection. With this method, we can target alteration where it was previously random.
Disadvantage: takes 2 generations
What is cloning / nuclear transfer?
Nuclear transfer is a form of cloning. The step involves removing the DNA from an oocyte and injecting the nucleus, which contains the DNA to be cloned.
For cloning, where can donor cells be collected from?
- Skin / ear punch
- Liver cells
- Embryonic stem cells
These donor cells are then cultured
What was unique about Dolly the cloned sheep?
First cloned animal using somatic cells –> mammary gland cells.
Previously, frog eggs were not able to do this; would die at the tadpole stage
What animal is best for organ transplant and why?
Pigs - knocked out sugar that is important in organ transfer rejection
What are the steps of cloning?
- Collect donor cells and culture
- Enucleate egg (remove all nuclear material from cytoplasm)
- Combine with enucleated cytoplasm. Provide electric shock that will open pores in the cytoplasm. The donor cell will dump the nucleus into the cytoplasm of the enucleated oocyte.
- Let develop to a later stage –> freeze –> transfer surgically to a recipient
What are the advantages and disadvantages of cloning?
Advantage: make genetically engineered in one generation, more efficient
Disadvantage: Expensive, less efficient in livestock
How are glow-in-the-dark pigs from UNL made?
Using gene from sea coral
When would spermatogonial germ cell transplantation be used?
We would do this with 2 mammals
What are the steps of spermatogonial germ cell transplantation?
- Isolate primitive sperm cells from the donor testis (biopsy / whole organ)
- Stem cells into recipient male (cease sperm production
- Rete tubules = target locations. Set up shop in adluminal/basal compartment
What would the result of spermatogonial germ cell transplantation be?
Recipient produces mature sperm from donor
What type of damage(s) is done to the recipient in spermatogonial germ cell transplantation?
- Heat testis up
- Radiation kills sperm
- Antagonism GnRH
When would spermatogonial germ cell transplantation be used?
In cattle
Using genetically superior bull in range location (don’t want them to get injured)
What are the steps of rectal palpation in cattle?
- Approach cow to be palpated
- Arm covered with glove should be lubricated
- Hand is inserted by forming the thumb and fingers into a cone tip, with a slight rotary motion
- Rake fecal material out
- Push down on rectum to feel repro tract
Where should be genital tract be when palpating cows?
Should lie below the floor of the pelvis
What does the cervix feel like during rectal palpation of cows?
It appears as a firm rope-like structure
Why would we use estrous synchronization?
- Group females for parturition
- Reduce time required for estrous detection
- Eliminate estrous detection with timed insemination
What is the principle of using progestogens for estrous synchronization?
Maintain the cow under the influence of progesterone until CL regresses, remove progesterone - animal responds to decrease progesterone with estrus 2-5 days later
How can progesterones be administered for estrous synchronization?
Injection
Feed
Implant
CIDR