Lecture 11: Assisted Reproductive Technologies II Flashcards
How can Gametes and Embryos be stored for Long Term?
- slow-cool cryopreservation –> freezing an egg or embryo with slow-cooling, usually within hours (ice crystals may form, causing damage) –> 66% freeze-thaw survival rate
- vitrification –> “flash freezing” an egg or embryo with extremely rapid cooling, usually within minutes, making it look “glass-like” (no time for formation of ice crystals; but needs higher [cryoprotectants] to be added) –> 83% freeze-thaw survival rate
- Lyophilization –> RT storage and alternative to cryopreservation
What is Cryobiology and when is the right time to use it?
it is the use of very low temperatures to preserve structurally intact living cells and tissue
- removes water and adds cryoprotectants
- storage periods for sperm is “indefinite” but typically 5-10 years
Egg Freezing: Why?
- undergo treatment for cancer/other illness that may affect future fertility potential
- undergoing in vitro fertilization
- wish to preserve younger eggs for future use
Embryo Freezing: Why?
- keeps extra embryos alive
- if IVF process fails the first time to have second baby
- saved and donated for someone else or to research
What are the types of Pre-impantation genetic testing (PGT-A)?
What are the 2 types of preimplantation Genetic Testing (PGT)?
PGT - Aneuploidy (PGT-A):
- screening detection of aneuploidies/chromosomal abnormalities
- ex. trisonomy 21
PGT-Monogenic (PGT-M):
- diagnostic for single gene disorders within lineage
- ex. sickle cell anemia, cystic fibrosis, Huntington’s, fragile-X, spinal muscular dystrophy
What are some applications of PGTs?
PGT-A:
- risk for aneuploidy –> advanced maternal age, prior triosomic conception
- prior failed IVF cycles/recurrent pregnancy loss
- sex selection for X-linked disorders
PGT-M:
- KNOWN single gene disorders
- HLA-typing, allows selection of embryos that are histocompatible with live siblings –> sibling can be a donor
Describe the pathway of Somatic Cell Nuclear Transfer - SCNT.
Describe the pathway of Reproductive Cloning.
- takes the nucleus of adult cell (containing DNA)
- from the egg, removes the nucleus and takes the rest of cell
- put together, will create a clone that is identical to the individual that gave the nucleus
Describe the pathway of Therapeutic Cloning.
- consists of an embryo with stem cells that contain the same DNA
What is the difference between Reproductive and Therapeutic Cloning?
What are the cloning regulations around the world?
United States:
- embryonic stem cell research permitted
- therapeutic and reproductive cloning is legal
UK, Sweden, Belgium:
- embryonic stem cell reseach and therapeutic cloning permitted
- reproductive cloning is banned
Canada:
- embryonic stem cell research permitted
- Therapeutic and reproductive cloning is banned
China, India, Japan, South Korea, Thailand, Vietnam:
- embryonic stem cell research and therapeutic cloning permitted
- reproductive cloning is banned
What is the process of Transgenesis?
- process introduces new genes into progeny
What is an example of Transgenesis?
Insulin:
- human insulin gene inputed with bacteria to be cultured and then extracted to create more pure insulin compared to animal insulin gene
How does wild life cloning work?
used for endangered species populations
What is an example to Wildlife cloning?
the regeneration of the endangered species, the Przewalski Horse –> Kurt
What is Gene Knock out?
gene editing where insertion of defective DNA sequences in gene or deletion of part of gene
- to not be expressed to prevent defective progeny
- associate knock-out gene with process or structure that was made abnormal by knock-out
