Biotechnology and Animal Breeding Flashcards
What is biotechnology?
broadly defined as applying biological knowledge to practical needs
What are the two categories for animal breeding perspectives?
- reproductive technologies
- molecular technologies
What are the types of reproductive technologies?
- AI
- Estrus Synchronization
- Embryo Transfer
- Sex Control
- Cloning
What are the types of molecular technologies?
- DNA Fingerprinting
- Marker Assisted Selection
- Gene Transfer
What is sex control?
- sperm sexing/sorting
- determine sex of embryos, the ability to generate just male or female offspring
What is cloning?
creating a genetically identical individual, asexual
What is marker assisted selection?
marker improves precision of selection
What is gene transfer?
ability to produce transgenics
What does the extent of the impact of biotechnology in animal breeding depend on?
- effectiveness
- practicality
- cost
- public perception
What is animal breeding a branch of?
a branch of genetics
What is reproduction an aspect of?
an aspect of physiology
What are selection and mating decisions made in context of?
available reproductive technologies
What does artificial insemination use?
semen collected from males
How is semen used for artificial insemination?
used fresh, cooled or frozen
Why is AI not always easy or practical?
- females in heat
- moved to breeding area
- properly inseminated at correct time
What is estrus synchronization?
use of hormones to induce females to come into heat at same time
What is estrus synchronization?
use of hormones to induce females to come into heat at same time
Why is estrus synchronization done?
to reduce the number of days to inseminate
What does PGF2α (2 is a subscore thing) cause?
a regression of CL and decrease in progesterone synthesis, causing ovulation to occur
What does Progestogen do?
negative feedback on hypothalamus by blocking LH and FSH
What does GnRH do?
ovulation/luteinization of growing follicle
What is Cidr?
controlled internal drug release, released progesterone into animal in different intervals
What is embryo transfer?
collection of embryos from superior donor females which are then transferred to less-superior recipient females
What is done to the donor for embryo transfer?
she is superovulated
How is an animal made superovulated?
hormone injection causing her to develop and release more ova than normal
What happens after the donor is inseminated?
embryos are transferred to recipients or frozen
What does embryo transfer allow?
females to have many more offspring than normal
What are some problems with embryo transfer?
- identifying candidates is difficult due to limited data
- certain problems for genetic evaluation
Why are there problems with genetic evaluation for embryo transfer?
- traits with maternal effects
- recipients usually not high quality animals
____ is to the female as _____ is to the male.
embryo transfer; AI
Is embryo transfer cheaper or more expensive than AI?
more costly
Is embryo transfer easier or more difficult than AI?
more difficult
What must be done for embryo transfer if using fresh embryos?
must synchronize donor and recips
Why must donor and recips be synchronized if using fresh embryos?
embryos have to implant in the recip, so the recip should be in the same physiological state as the donor (same level of hormonal activity) to prevent rejection of embryo
If embryos are not fresh, must the donor and recip be synchronized?
you just need to focus on the recip
What are the steps of embryo transfer?
- superovulation of donor with gonadotropins
- AI (5 days after initiating superovulation)
- nonsurgical recovery of embryos (6 to 8 says after insemination)
- foley catheter for recovering embryos
- isolation and classification of embryos
- storage of embryos indefinitely in liquid nitrogen or at 37 C or room temp for 1 day)
- transfer of embryos to recipients surgically or nonsurgically
- pregnancy diagnosis by palpation through the rectal wall 1 to 3 months after embryo transfer
- birth (9 months after embryo transfer)
What is In Vitro Fertilization?
fertilization in a test tube
How are eggs collected for in vitro fertilization?
eggs (oocytes) collected from donor female through aspiration of the reproductive tract
What is done with eggs after collected?
incubated/matured and fertilized in lab, then frozen or transferred to recip
know basic principle of IVF (slide 12)
(female) hormonal treatment -> harvest the ovum -> mature ovum
(male) natural ejaculation -> collect semen -> motile sperms
-> mix in a test tube -> keep to develop embryo -> transfer to mother
What does ART stand for?
assisted reproductive technique
What are the two ways to harvest eggs?
- Ultrasound Guided Aspiration
- Laparoscopy
What does it mean to harvest eggs by ultrasound guided aspiration?
pull eggs into one single location
What is a laparoscopy in terms of egg collection?
minimal invasive surgery that uses thin, lighted tube put through an incision in the belly to look at the abdominal or female pelvic organs
At what stage are embryos transferred?
8-cell stage or blastocyst stage
What does it mean if embryos are in the blastocyst stage?
have overcome heat shock
What are the advantages of In Vitro Fertilization?
- increased number of possible pregnancies
- collect eggs repeatedly from same donor at short intervals
- doesn’t have to be at certain stage of estrous cycle
- there is no need to superovulate the donor females
- decreased generation interval
- eggs collected from young, prepubertal females
What are disadvantages of In Vitro Fertilization?
- expensive
- success rate relatively low
- abnormalities of offspring
How is the sex of embryos determined?
by physically removing a few cells and examining chromosomes
Why are embryos sexed?
so you can ship just to those that need male or female
What are the two methods used to determine sex of embryos?
- Y-specific DNA probe
- Y-specific DNA primer and PCR
What is a DNA probe?
a predetermined sequence
How does Y-specific DNA probe work for sexing embryos?
if it doesn’t bind you know it is female, and if it hybridizes you know it is male
What does PCR stand for?
polymerase chain reaction
What are DNA primers?
short sequences that range from 17 to 21 nucleotides
How does Y-specific DNA Primer and PCR work for sexing embryos?
primer orients DNA polymerase to bind to specific place in Y region. Then use PCR which amplifies DNA
What is sperm sorting?
it is possible to sort sperm carrying female sex chromosome from male sex chromosome
Is sperm sexing commercially viable?
the rate used to be too slow to make it commercially viable, but now it is
What is the method used to sort sperm?
flow cytometry
What is flow cytometry?
measurement of cells based on DNA content of sperm cells, as they flow by a detector
How do X chromosome bearing cells compare to Y?
X chromosome bearing cells contain 4% more DNA than Y chromosome
Know steps of flow cytometry
slide 26-27
What are sorted out when sperm are sorted?
dead sperm/ sperm that don’t have a detectable charge
When was the ability to separate X and Y sperm researched?
1980s
When was the ability to sex sperm commercially available?
2004
What does sexing semen for cattle take advantage of?
female sperm having 3.8% more DNA
Is sexing sperm for cattle a fast process?
no it is a slow process since it takes 4 times longer to process the semen
What are the results of sexing semen for cattle?
- ability to produce desired sex of calf with 90% accuracy
- AI companies can package less sperm cells since the dead and abnormal cells are sorted off
- Semen now commercially available
How is sexing semen for cattle applied?
- first used on dairy to reduce number of bull calves (bulls worth $50 and heifers valued at $350)
- sex choice depends on herd genetics and marketing programs
- commercial herds want male calves from cows
- seedstock herds want male calves for resale
What is the point in sex control?
- one sex is more valuable than the other depending on the operation
- better economics
- crossbreeding systems
How is one sex more valuable than the other depending on the operations?
- males for meat
- females for milk
How does sex control contribute to better economics
sire strong for maternal traits can be used to produce female offspring
What is cloning?
technology for the production of genetically identical individuals asexually
Is embryo splitting cloning?
it’s more of a way of improving efficiency of embryo transfer than cloning
What is embryo splitting?
cutting embryo in half to produce twin embryos and then transfer to recips
How is cloning done?
Nuclear Transplantation
What are the steps of cloning by nuclear transplantation?
- eggs matured in vitro
- nuclei surgically removed
- individual cells from multi-cell embryo inserted into each ova (egg)
- the ova support growth
- produce a number of identical embryos
- embryos can be transferred or frozen OR can serve as cell donors for repeated cycles of cloning by nuclear transplantation
- measure cloned animals for performance
How are cloned animals measured for performance?
- progeny test
- statistical analysis
- shorten Gi (gestation interval)
What are the types of cloning?
- reproductive
- therapeutic
What is reproductive cloning?
results in a live animal
What is therapeutic cloning?
leave cells at stage where they can be used for therapeutic reasons (like stem cells?)
What is a downside to cloning if you need to cross clonal lines?
inbreeding depression
What are benefits of cloning?
- big jump in genetic merit
- increased uniformity of performance
- observed variation due to environment
- increase accuracy of selection
How has cloning led to a jump in genetic merit?
one generation of genetically elite animals
What does it mean that there is observed variation due to environment as a result of cloning?
despite being a clone, the environment will influence the behavior of the individual
-the higher the heritability for the trait, the more uniform the population for that trait
How does cloning increase accuracy of selection?
- by virtue of large amounts of performance data for each clonal line
- increased selection intensity by providing virtually unlimited access to very best clonal lines
What are problems with cloning?
- small number of clonal lines
- single clonal line comprises significant proportion of population
- time consuming to genetically evaluate each line before making commercially available
- some abnormal newborns
- many die
- expensive
What results if there is a small number of clonal lines?
- lose genetic variation needed for future improvement
- excessive inbreeding
What results if single clonal line comprises significant proportion of population
-risk that line could be susceptible to pathogen or environmental stress which lead to widespread loss of production
How is cloning expensive?
waste of creating clonal lines, then you select only a few and discard the rest
What was the first adult animal cloned?
Dolly
Where was Dolly cloned?
Roslin Institute
Who cloned Dolly?
Ian Wilmut
How many attempts were made before Dolly was born?
277
What tissue were the cells used to make Dolly collected form?
mammary tissue
Are clones healthy?
not conclusive
What is inserted into ovum to clone?
mature, differentiated cells
What must be in the mature differentiated cells that are inserted into ovum?
all genes necessary for growth must be there
What happens to somatic cell’s genes for cloning?
“turned on” again to produce different types of tissues
How do cloned animals age?
rapidly
What happens to telomeres of cloned animals?
unravel
What are telomeres?
- protective caps
- specialized terminal structures on chromosomes that ensure the maintenance and accurate replication of chromosome
What is progeria?
a disorder that caused rapid aging
Could we use cloning on animals that have proven genetic worth?
yes
What is the roslin method of cloning (Steps)?
SLIDE 48
What is somatic cell nuclear transfer?
technique for creating ovum with donor nucleus
What is somatic cell nuclear transfer used in?
- embryonic stem cell research
- “therapeutic” cloning
- reproductive cloning
What was/is the first step of somatic cell nuclear transfer?
reproductive cloning
What does SCNT stand for?
somatic cell nuclear transfer
What are the limitations of somatic cell nuclear transfer?
- stresses placed on both egg cell and introduced nucleus are enormous
- Dolly
- procedure cannot be automated
- biochemistry involved in reprogramming differentiated somatic cell nucleus and activating recipient ovum
- not all of donor’s genetic info is transfered
- clones not perfect copies of donor nucleus
Explain SCNT limitations in relation to DOlly?
- 277 ova used
- 29 viable embryos
- 3 lambs
- 1 survived
What does stress placed on egg cell and nucleus result in for SCNT?
high loss in resulting cells
Why can SCNT not be automated?
it has to be done manually under a microscope
Is the biochemistry involved in reprogramming differentiated somatic cell nucleus and activating recipient ovum well understood?
no
Why is not all of donor’s genetic information transferred from SCNT?
- mitochondrial DNA is left behind
- hybrid cells retain those structures which originally belonged to ovum
What proposals have been raised for SCNT?
use in human stem cell research
What concerns have been raised over SCNT use in human stem cell research?
set of concerns beyond moral status of created embryo
What has been created from human stem cell research?
blastula
What does the creation of blastula in human stem cell research lead to?
reproductive cloning of humans
When is there a higher chance of implantation?
at blastula stage
What controversies have been brought up over SCNT?
- reproductive cloning of humans and human stem cell research
- appropriate sourcing of ovum that are needed (for human stuff?)
What first step would be used for reproductive cloning of humans and human stem cell research?
-creation of nuclear transferred embryo
What do those concerned with human cloning/human stem cell research advocate for?
strong regulation of SCNT
What is required for human cloning/human stem cell research?
human ova
What is human ova obtaine from?
women
What is the most common source of ova?
produced in excess of clinical need during IVF treatment
What is same sex mating?
mating of individuals of same sex
- mate best sires to best sires
- also mating individuals to themselves
What procedures would same sex mating use?
procedures for nuclear transplantation and embryo transfer
What is the technique used for same sex mating?
nuclear fusion
What is nuclear fusion?
artificial fertilization that combines the nuclei of two gametes
Is same sex mating currently working?
no it is theoretical
Why may same sex mating never work?
may need chromosomes from both male and female origins to support fetal development
Why should same sex mating be attempted?
increase selection accuracy and intensity
What would result from a male x male mating?
- 2 males (XY)
- 1 female (XX)
- 1 no go (YY)
What would result from a female x female mating?
-all females (XX)
What is mating individuals to themselves called?
selfing
What is DNA fingerprinting?
lab method for graphically characterizing an individual’s DNA
What sample is taken for DNA fingerprinting?
sample of blood or other tissue
What is done after sample is collected for DNA fingerprinting?
DNA extracted
DNA is ______.
polymorphic
What does polymorphic mean?
at least 2 alternative alleles occurring in population
What happens after DNA is extracted for dna fingerprinting?
DNA is chemically copied and placed on gel
How is DNA sorted on the gel?
by electrophoresis
What is electrophoresis?
method that separates macromolecules, either nucleic acids or proteins-on the basis of size, electric charge, and other physical properties
Can twins be genetically told apart?
yes
What are the steps of DNA fingerprinting (in notes)?
- DNA Extraction
- Polymerase chain reaction (more steps under this in notes)
- put on gel
- gel electrophoresis
What are the steps of PCR cycling condition?
- denaturation step (94 C)
- annealing step (36 C)
- elongation step (72 C)
How many bars appear on the gel if heterozygote?
2
What results from gel electrophoresis?
pattern of bands that represent the presence of specific alleles at number of loci
What does PCR do?
chemically copy DNA
What are the uses of DNA fingerprinting?
- multiple sire pasture system
- identify parents more accurately
- predict hybrid vigor
What is multiple sire pasture system used instead of?
AI or hand mating
What does DNA fingerprinting multiple sire pasture system allow you to do?
see which bull is able to impregnate more females by natural cover
How does DNA fingerprinting allow parents to be identified more accurately?
avoid faulty pedigrees
_______ will have greater hybrid vigor.
less related individuals
How is genetic merit currently evaluated?
in the form of EPDs, which are computed from phenotypes on the individual and its relatives
What is marker assisted selection?
selection for specific alleles using genetic markers
What is a genetic marker?
detectable genes for DNA fragments used to identify alleles at linked locus
When talking about genetic markers, what does detectable mean?
we can identify different versions of alleles
Why are some alleles detectable (in terms of genetic markers identifying them)?
they produce easily distinguishable phenotypes
How are genetic markers now detected?
DNA fingerprinting
What is Linkage Analysis?
mathematical process that uses information from specially bred populations to determine whether 2 loci are linked and how closely
What are the best “markers”?
the alleles of interest themselves
What is marker assisted selection more difficult to use in?
polygenetic traits
What are examples of polygenetic traits?
growth rate, racing ability
Is the performance of polygenetic traits affected by one gene?
not much
How do geneticists estimate linkage distance?
examining the rate at which genes segregate at 2 loci recombined
When does crossing over occur?
if distantly linked
If crossing over occurs, how does that affected marker assisted selection?
marker will “code” for alternate allele
What is a more realistic approach to genetic merit evaluation?
phenotypes and DNA tests on the individual and its relatives are combined, through National Cattle Evaluation (NCE), to produce marker-adjusted EPDs, upon which selection decisions are made
Is that realistic approach to genetic merit evaluation used?
maybe someday, but it is too far off in the future to be of practical value
What are the types of molecular markers?
- Restriction Fragment Length Polymorphism (RFLP)
- Microsatellites
- Single Nucleotide Polymorphism (SNP)
- Copy Number Variation (CNV)
What is Restriction Fragment Length Polymorphism?
exploits variation in homologous DNA sequences to distinguish between individuals
What is Microsatellites?
a tract of repetitive DNA which can be tracked and associated with differences in Phenotypes (ex. can be used to tract inheritance of genes in families)
What is Single Nucleotide Polymorphism?
a single base change in sequences of organisms that are associated with performance or disease outcomes
What is Copy Number Variation?
structural alterations in genome which results in abnormal number of copies of one or more sections of the DNA
What is gene transfer?
transplantation of specific genes from one individual to another
What does gene transfer involve?
transfer of gene coding for important proteins from domestic animals to bacteria
What happens when the bacteria are genetically altered (gene transfer)?
the bacteria manufacture the protein cheaply
Is gene transfer a fast or slow process?
slow
Why is gene transfer a slow process?
- only one copy of a gene is transferred at one time
- takes generations to spread that gene throughout population
- gene could end up anywhere in the genome
What does transgenic mean?
an individual has received genetic material by gene transfer
What are the types of transgenic animals?
- dairy cows
- animals
What do transgenic dairy cows do?
produce human insulin
What is a reason for making transgenic animals (not dairy cows)?
genes for disease resistance
Is gene transfer easier to do in animals or plants?
plants
Why is gene transfer easier in plants than animals?
many traits are simply inherited and simple regulated
What resistances are gene transferred into plants?
- pest resistance
- insecticide resistance
