biotechnology and animal breeding Flashcards
1
Q
what is biotechnology broadly defined as?
A
applying biological knowledge to practical needs/problems
2
Q
what are the two animal breeding perspectives?
A
reproductive technologies(species level) and molecular technologies(genetic level)
3
Q
what are the five types of reproductive technologies?
A
- AI
- estrus synchronization
- embryo transfer
- sex control (determining the sex of the embryo)
- cloning (asexual repro)
4
Q
what are the three types of molecular technologies?
A
- DNA fingerprinting
- marker assisted selection
- gene transfer
5
Q
what does the extent of impact of biotechnology in animal breeding depend on? (4)
A
- effectiveness
- practicality
- cost
- public perception
6
Q
what is artificial insemination?
A
semen is collected from males and then used fresh, cooled, or frozen to breed females
7
Q
why isn’t artificial insemination always easy or practical? (3)
A
- females need to be in heat
- additional cost of moving to breeding area
- properly inseminated at the correct time with ovulation
8
Q
what are the three hormones used in estrus synchronization?
A
- PGF2a
- progestogen
- GnRH
9
Q
what is estrus synchronization?
A
when hormones are used to induce females to come into heat at the same time
10
Q
what is the benefit of estrus synchronization?
A
reduces number of days to inseminate
11
Q
what is PGF2a? what does it cause?
A
(prostaglandin) hormone used in estrus synchronization; it causes regression of the corpus luteum and a decrease in progesterone synthesis
12
Q
what does progestogen cause?
A
negative feedback on the hypothalamus by blocking LH (luteinizing hormone) and FSH (follicle stimulating hormone)
13
Q
What does GnRH stand for? what does it cause?
A
gonadotropin releasing hormone; causes ovulation/luteinization of a growing follicle
14
Q
what are the steps of embryo transfer?
A
- donor is superovulated
- donor is inseminated
- after an interval of time, embryos are transferred to recipients or frozen
15
Q
what is embryo transfer?
A
collection of embryos from donor females and transferring them to recipient females
16
Q
what does the surrogate mother provide in ET?
A
the environment for the embryo
17
Q
what does the donor mother provide in ET?
A
genetics
18
Q
what is the advantage of embryo transfer?
A
allows females to have many more offspring than normal
19
Q
what are difficulties in embryo transfer?
A
- 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
20
Q
what is to the female as AI is to the male?
A
Embryo Transfer
21
Q
what is more costly and difficult: AI or ET?
A
ET
22
Q
what are the nine steps of embryo transfer?
A
- 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)
23
Q
what does “in vitro” mean?
A
in a test tube
24
Q
what does “in vivo” mean?
A
in live animal
25
what does “in saco” mean?
in a plastic bag
26
what is the process of in vitro fertilization?
1. eggs are collected from donor female through aspiration of the reproductive tract
2. eggs are incubated / matured and fertilized in lab
3. eggs are frozen or transferred to recipient
27
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
28
what are the two ways to harvest eggs?
1. ultrasound guided aspiration
2. laparoscopy
29
during what stages are embryos usually transferred?
the 8-cell stage or blastocyst stage
30
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
31
what are the disadvantages of in vitro fertilization?
- expensive
- success rate is relatively low
- abnormalities of offspring
32
are clones healthy?
yes, they are like any other animal
33
who is the scientist that cloned dolly?
Ian Wilmut
34
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
35
what are some suspected genetic negatives of cloning adult animals?
- age rapidly
- telomeres on chromosomes unravel
36
why would a cloned animal have different performance?
they would have the same genetic worth but performance would differ due to environment
37
what are the steps of cloning an ewe (the roslin method)?
1. an ewe provides the mammary cell to be cloned
2. a mammary cell contains copies of all genes needed to produce a sheep, but only genes for proteins required by mammary cells are active
3. 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
4. another (or same) ewe provides the egg
5. the egg is preserved in a laboratory dish
6. the nucleus is dislodged from the cell
7. 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
8. clusters of embryonic cells are grown
9. embryos are implanted into a surrogate mother
10. the resulting lamb is a clone of the donor ewe
38
what is somatic cell nuclear transfer?
a technique for creating ovum with a donor nucleus
39
when is somatic cell nuclear transfer used?
- embryonic stem cell research
- “therapeutic” cloning
- the first step of reproductive cloning
40
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
41
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)
42
what two procedures are used for same sex mating?
those for nuclear transplantation and embryo transfer
43
what is the technique called that is used for same sex mating?
nuclear fusion
44
what is nuclear fusion?
artificial fertilization that combines the nuclei of two gametes
45
why might same sex mating never work?
you may need chromosomes from male and female origins to support fetal development
46
why do we attempt same sex mating?
it appears to be the best way to increase selection accuracy and intensity
47
what are the offspring of a male x male cross? (same sex mating)
- 2 males (XY)
- 1 female (XX)
- 1 no go (YY)
48
what are the offspring of a female x female cross? (same sex mating)
all females (XX)
49
what is selfing?
mating individuals to themselves
50
what is marker assisted selection?
selection for specific alleles using genetic markers
51
what is a genetic marker?
detectable genes (aka we can identify different versions of its alleles) or DNA fragments used to identify at linked locus; hint as to which animal is best for a trait
52
what makes some alleles detectable?
because they produce easily distinguishable phenotypes
53
how are genetic markers detected?
DNA fingerprinting
54
what is linkage analysis?
mathematical process that used information from specially bred populations to determine whether 2 loci are linked and how closely (we have linked this allele to the presence or absence of something and that is used as a marker)
55
what are the best markers in marker assisted selection?
the alleles of interest themselves
56
with what kind of traits is marker assisted selection more difficult to use?
polygenic traits
57
how do geneticists estimate linkage distance?
by examining the rate at which genes segregating at 2 loci recombined (did they stay together during crossing over?)
58
what are the four types of markers
1. restriction fragment length polymorphism (RFLP)
2. micro satellites
3. single nucleotide polymorphism (SNPs)
4. copy number variation (CNVs)
59
what are the steps of restriction fragment length polymorphism?
1. extract DNA from each individual
2. use a restriction enzyme to cut DNA
3. gel electrophoresis
4. visualize the gel and identify the alleles
60
what are micro satellites?
small bits of DNA that repeat (tandem repeats)
61
how are micro satellites used as markers?
by measuring the number of repeats
62
What is single nucleotide polymorphism (SNPs)?
one base change
63
what is copy number variation?
structural variation
64
what is gene transfer?
transplantation of specific genes from one individual to another
65
what types of genes are being transferred in GT?
genes coding for important proteins from domestic animals to bacteria
66
what is the function of bacteria in GT?
they receive the gene coding for an important protein and then manufacture the protein cheaply
67
what does Bt stand for in Bt corn?
Bacillus thuringiensis
68
why is GT a slow process?
- only one copy of a gene is transferred at one time
- it takes generations to spread that gene throughout a population
- the gene could end up anywhere in the genome
69
why is Bt corn good?
the cry gene breaks down in the gut of insects and kills them, functioning as a natural pesticide
70
what is a transgenic animal?
an individual that has received genetic material by gene transfer
71
what do transgenic dairy cows produce?
human insulin
72
what genes to transgenic animals usually receive?
genes for disease resistance
73
why is GT easier to do in plants?
many plant traits are simply inherited and simply regulated
74
what is GT used for in plants?
pest resistance and insecticide resistance
75
what is sex control?
the possibility to determine the sex of an embryo by physically removing a few cells and examining chromosomes; sperm sorting due to male and female chromosome
76
what are the two methods of sex control?
1. y-specific DNA probe
2. y-specific DNA primer and PCR
77
what is flow cytometry?
the method used in sex control to measure cells as the flow by a detector
78
what is the difference between male and female sperm that is measured for during flow cytometry?
the DNA content of the sperm cells; X chromosome bearing cells contain 4% more DNA
79
what is the process of flow cytometry?
1. semen is labeled with fluorescent dye called hoescht 33342 which bind to the DNA
2. as X chromosome is larger than Y, it absorbs a greater amount of dye
3. when exposed to UV light during flow cytometry, the X fluoresces brighter than Y
4. spermatozoa are encased in a single droplet of fluid as they pass the flow cytometer in a single file
5. spermatozoa are assigned an electric charge corresponding to its chromosome status
6. stream of X and Y droplets is then separated by means of electrostatic deflection and collected into separated collection tubes for subsequent analysis
80
what is the state of new technology for sexed semen in cattle?
- ability to separate X and Y sperm researched in 1980s
- made commercially available in 2004
- takes advantage of female sperm having 3.8% more DNA
- slow process since it takes 3 to 4 times longer to process the semen (than non-sexed)
81
what is the accuracy of sexed semen in cattle?
90%
82
why are less sperm cells packaged when the semen is sexed?
the dead and abnormal cells are sorted off
83
why was sexed semen first used for cattle?
in dairy to reduce the number of bull calves because bulls are worth $50 and heifers are worth $350
84
what does sex choice depend on when purchasing sexed semen for cattle?
herd genetics and marketing programs; commercial and seedstock herds want male calves and dairy wants female calves
85
why do we bother with sex control for cattle?
- one sex is more valuable than the other (males for meat, females for milk)
- better economics (sire strong for maternal traits should be used to produce female offspring)
- crossbreeding systems
86
what is cloning?
technology for the production of genetically identical individuals
87
what is embryo splitting?
cutting an embryo in half to produce twin embryos; more of a way of improving efficiency of ET than cloning
88
what is the process of cloning by nuclear transplantation?
eggs are matured in vitro, nuclei are surgically removed, individual cells from multi-cell embryo inserted into each ova (ova support growth), they produce a number of identical embryos
89
what is an egg called where the nuclei has been surgically removed
enucleated egg
90
why do you need to cross clinal lines?
inbreeding depression
91
what are the benefits of cloning?
- big jump in genetic merit (in one gen, you can produce a genetically elite animal)
- increased uniformity of performance
- any variation is due to the environment
- increases accuracy of selection
92
when cloning, what does higher heritability of a trait do for the population?
the population will be more uniform for that trait
93
how does cloning increase the accuracy of selection?
by virtue of large amounts of performance data for each clinal line; increased selection intensity by providing virtually unlimited access to the very best clinal lines
94
what are some problems with cloning?
- if there is a small number of clonal lines then you lose genetic variation needed for future improvement (excessive inbreeding)
-if a single clonal line comprises a significant proportion of the population then there is a risk that that line could be susceptible to a particular pathogen or environmental stress leading to a widespread loss of production
- it is time consuming to genetically evaluate each line before making them commercially available
- some abnormal newborns
- many die
- expensive (waste of creating many clonal lines and then selecting only a few and discarding the rest)
95
what is DNA fingerprinting?
the lab method for graphically characterizing an individuals DNA
96
what is the process of DNA fingerprinting?
1. take a small sample of blood or other tissue
2. extract the DNA
3. DNA is chemically copied and placed on gel via PCR
4. DNA is then sorted by electrophoresis resulting in a banding pattern that represents the presence of specific alleles
97
what are molecular technologies?
using technology at the DNA level
98
what is DNA fingerprinting possible?
because DNA is polymorphic (aka it has at least 2 alternative alleles occurring in the population)
99
what is electrophoresis?
a method that separates macromolecules (either nucleic acids or proteins) on the basis of size, electric charge, and other physical properties
100
what are the three steps of a PCR test?
1. denaturation - solution is heated to 94 C which breaks down the hydrogen bonds of the DNA separating the DNA into single strains
2. annealing - solution is cooled to 50-60 C allowing the DNA primers and the DNA polymerase enzyme to bind to the individual strands; the nucleotides from the added mixture solution will pair with the individual strands
3. elongation - they form a new complementary strand of DNA; a new duplicate double-stranded DNA molecule has been formed from each of the single strands of the original sample molecule; cycle is then repeated about 35 to 40 times forming millions of copies
101
what do patterns of bands represent after using electrophoresis in DNA fingerprinting?
they represent the presence of specific alleles at a number of loci
102
what are some uses for DNA fingerprinting?
- multiple sire pasture system (allows you to see which bull is able to impregnate more females by natural cover)
- identify parents more accurately (helps to avoid faulty pedigrees)
- predict hybrid vigor (less related individuals will have greater hybrid vigor in offspring)
103
what three information sources are used to gain accurate evaluation of genetic merit?
pedigree, phenotype of individual, and collateral relatives
104
how is genetic merit evaluated?
in the form of EPDs (computed phenotypes on the individual and its relatives)
105
what is an example of gene transfer?
the lysozyme gene is transferred from humans to goats to improve the shelf life of their milk
