LATG 10: Genetic Engineering of Laboratory Animals

Question 1

What best describes a transgenic animal?

Answer 1

An animal whose chromosomes contain DNA from an external source

Question 2

True or False: About 80% of the genes present in humans are also present in the mouse genome.

Answer 2

True

Question 3

Which term represents the hereditary information that is present in an animal?

Answer 3

genome

Question 4

What is a transgene?

Answer 4

The fragment of DNA that is introduced into the nucleus of a cell

Question 5

True or False: Barrier access to an animal room increases the risk of introducing disease entities to valuable genetically modified lines.

Answer 5

False

Question 6

True or False: A gene’s phenotype develops in utero and can always be observed after birth.

Answer 6

False

Question 7

True or False: With barrier access to a room, investigators must rely on animal care staff to handle all animal needs.

Answer 7

True

Question 8

True or False: Overbreeding to obtain the number of mice needed with a particular genotype is unacceptable in a transgenic animal facility.

Answer 8

False

Question 9

True or False: If a large number of animals must be euthanized because gene expression is inadequate, animal care staff may need emotional support.

Answer 9

True

Question 10

True or False: Every transgenic animal facility should have a mechanism for observing, documenting, and reporting health concerns regarding breeding or unique phenotypes.

Answer 10

True

Question 11

True or False: Genetically modified mice have the same housing and nutrition needs as any other mice in the facility.

Answer 11

False

Question 12

True or False: Whenever a dam experiences dystocia, oxytocin is effective at inducing labor.

Answer 12

False- not always effective

Question 13

To produce the embryos needed to produce gene-targeted animals, the dosage and timing of the hormone injections to induce superovulation must take into consideration which of the following factors?

Answer 13

light/dark cycle of facility, strain of female

Question 14

What is an initial observation indicating a successful mating?

Answer 14

vaginal plug

Question 15

Females with a litter from implanted fertilized eggs are called:

Answer 15

surrogate mothers

Question 16

If fertilized eggs are required, along with egg donor females, what animals are required?

Answer 16

stud males

Question 17

Placing pups with a female other than the one who gave birth to them is called cross-fostering.

Answer 17

cross fostering

Question 18

The successful breeding of transgenic mice may be affected by what factors?

Answer 18

lighting, noise, odors, stress

Question 19

True or False: Embryos can be transferred to recipient mice surgically if the embryos are at least 3.5 days old.

Answer 19

False- exactly 3.5 days old

Question 20

True or False: In the production of gene-targeted animals, mating with a stud makes the recipient female pseudopregnant.

Answer 20

False

Question 21

True or False: Pronuclear injection provides the scientist with a more specific tool than gene-targeted mutation for placement of the transgene.

Answer 21

False

Question 22

True or False: To construct a transgene, the scientist must start with an existing piece of DNA that originated in a living organism.

Answer 22

False

Question 23

True or False: Pronuclear injection introduces a transposon-flanked DNA sequence with an enzyme that inserts multiple copies of the DNA into the genome.

Answer 23

False- multiple copy segments can be detrimental

Question 23

True or False: Pronuclear injection introduces a transposon-flanked DNA sequence with an enzyme that inserts multiple copies of the DNA into the genome.

Answer 23

False- multiple copy segments can be detrimental

Question 24

True or False: A transposon is a DNA sequence obtained from bacteria.

Answer 24

True

Question 25

True or False: All animals produced by pronuclear injections of the same transgene have the same phenotype.

Answer 25

False

Question 25

True or False: All animals produced by pronuclear injections of the same transgene have the same phenotype.

Answer 25

False

Question 26

What are alleles?

Answer 26

Copies of the same gene

Question 27

If a transgene is integrated in one of the chromosomes of a pair, the animal is said to be:

Answer 27

hemizygous

Question 28

True or False: Wild-type animals are more commonly used to start a transgenic line because it is easier to observe a phenotypic change than in inbred strains.

Answer 28

False

Question 29

True or False: Offspring of two hemizygous parents inherit at least a copy of the transgene.

Answer 29

False- 25% will have no copy of the gene

Question 30

True or False: PCR can be used to genotype an animal born after pronuclear injection of a transgene.

Answer 30

True

Question 31

True or False: CRISPR/Cas9 may be used to selectively knock out genes of interest.

Answer 31

True

Question 32

True or False: Eukaryotic cells have the ability to develop into any kind of cell in the body.

Answer 32

False- embryonic stem cells do

Question 33

True or False: Using engineered systems for gene targeting eliminates the need for embryonic stem cell culture.

Answer 33

True

Question 34

What is a genetically engineered animal that has had one or more genes from its genome functionally removed?

Answer 34

Knockout

Question 35

True or False: Mouse models have been developed that replace the mouse immune system with a human system.

Answer 35

True

Question 36

True or False: CRISPR is an engineered DNA identification mechanism.

Answer 36

False- it is a naturally occurring DNA identification mechanism

Question 37

True or False: The gene-targeted mutation derived from the injected embryonic stem cells is always present in the sperm of a male chimera.

Answer 37

False- The germ cells of a chimera may be derived from the host or from the ES cells.

Question 38

True or False: Embryonic stem cells used for gene-targeted mutations are grown in the presence of antibiotics.

Answer 38

True

Question 39

True or False: In genetically engineered mice known as knockouts, the transgene of interest is functional.

Answer 39

False

Question 40

True or False: To test for germline transmission, chimeras are mated to animals of the same strain from which their ES cells were derived.

Answer 40

False-To test for germline transmission, chimeras are mated to animals of the same strain as the blastocyst host.

Question 41

True or False: In order to avoid disturbing the litter, the best time to genotype a mouse is within two days of birth.

Answer 41

False- best done ~2 weeks

Question 42

True or False: Tail biopsies on adult mice should be done under anesthesia.

Answer 42

True

Question 43

True or False: The phenotype of mutant animals indicates the engineered change in DNA.

Answer 43

True

Question 44

True or False: Cryopreservation can be used to store frozen embryos, and subsequently recover the original genetic make-up of a mouse line when genetic drift has caused changes in the strain.

Answer 44

True

Question 45

What technique allows a mouse strain to be taken "off the shelf" but still be available for use when needed?

Answer 45

cryopreservation

Question 46

True or False: Sperm cryopreservation is a terminal procedure

Answer 46

True

Question 47

True or False: The Mutant Mouse Regional Resource Centers serve as centralized repositories for many mouse lines.

Answer 47

True

Question 48

What best describes "alleles"?

Answer 48

Copies of the same gene

Question 49

If a genetically modified mouse is dying and cannot be saved, it is important to attempt to save which of the following?

Answer 49

gonads

Question 50

What is the best age to genotype a mouse in order not to disturb the litter?

Answer 50

around weaning time

Question 51

To produce the embryos needed to produce gene-targeted animals, the dosage and timing of the hormone injections to induce superovulation must take into consideration which of the following factors?

Answer 51

the strain of the donor female and light/dark cycles

Question 52

If a transgene is integrated in one of the chromosomes of a pair, the animal is said to be:

Answer 52

hemizygous

Question 53

In which room access type are primary investigators allowed to conduct some manipulations, although facility personnel have the majority of contact with the animals?

Answer 53

limited access

Question 54

What best describes genetic engineering?

Answer 54

Manipulating DNA molecules to alter their composition

Question 55

What is the ideal age range for stud males?

Answer 55

3-8 months

Question 56

Cryopreserved embryos and sperm are incubated in which substance?

Answer 56

liquid nitrogen

Question 57

In the pronuclear injection technique, some females are mated to vasectomized males to:

Answer 57

induce pseudopregnancy

Question 58

Using the pronuclear injection technique, what is the average percentage of offspring carrying the transgene?

Answer 58

20%

Question 59

What is a genome?

Answer 59

The hereditary information contained in the DNA

Question 60

If only one allele is mutated using CRISPR/Cas9, what is the resulting animal known as?

Answer 60

a mosaic animal

Question 61

The introduction of an antibiotic resistance gene into a DNA fragment is used for what purpose?

Answer 61

It helps identify the cells that have integrated the transgene.

Question 62

Genetically engineered mice are often transported between institutions which often results in:

Answer 62

the need for more frequent sentinel testing.

Question 63

What best describes genetic engineering?

Answer 63

manipulating DNA molecules to alter their composition

Question 64

__________ refers to introducing additional DNA into the genome of an animal.

Answer 64

Transgenesis

Question 65

True or False: Most genes are specific to one species and are not found in animals of other species or genus.

Answer 65

False

Question 66

What are the 2 major differences between pronuclear injection and gene-targeted mutation?

Answer 66

Location: in pronuclear injection, the DNA is integrated in random locations of the chromosome; in gene-targeted a specific location is used Number: in pronuclear injection, many copies of the gene are integrated; in gene targeted only 1 is integrated

Question 67

What are the 3 standard types of access to a mouse breeding room?

Answer 67

full access, limited access, and barrier

Question 68

What observations should be made when a female has pups?

Answer 68

condition of nest, how many pups, whether the dam is attending to them

Question 69

True or False: Pronuclear injection provides the scientist with a more specific tool than gene-targeted mutation for placement of the transgene.

Answer 69

False

Question 70

What ways can a phenotype be expressed?

Answer 70

clinical exam, reproductive assessment, neurological tests, behavior tests, physiological tests, imaging, clinical chemistry, necropsy/histopath

Question 71

What are common stressors that may disrupt a recipient female's care of pups?

Answer 71

cage disturbances, loud/sudden noise, vibrations, lighting change (intensity and cycle), personnel changes

Question 72

What is the purpose of mating a female with a vasectomized male?

Answer 72

to induce pseudopregnancy

Question 73

Will all of the offspring of two hemizygous parents inherit at least a copy of the transgene?

Answer 73

no

Question 74

An animal that contains a targeted selection of new DNA that was designed to change a specific gene is called:

Answer 74

knockin

Question 75

An animal that has a fragment of DNA inserted to prevent a gene from being expressed is called:

Answer 75

knock out

Question 76

Why are mice from inbred lines preferred for producing transgenics?

Answer 76

it is easier to identify phenotype changes in mice that originally have identical phenotypes

Question 77

In creating a chimera, why is it recommended to use embryonic stem cells from a strain of a different coat color than the strain used to provide the blastocyst?

Answer 77

you can identify chimeras by differences in their phenotype as compared to parent strains

Question 78

True or False: Obtaining chimeras that have patches of fur of different colors is a clear indication that there is germline transmission of the gene-targeted mutation.

Answer 78

False

Question 79

What are the 4 types of animals needed for the production of transgenic animals?

Answer 79

egg donor (superovulated female), embryo-recipient (pseudopregnant female), stud male, vasectomized male

Question 80

What is the sequence of steps should be followed to prepare females for producing blastocytes in the developement of gene targeted animals?

Answer 80

inject PMSG, inject hCG, mate with stud male, harvest embryo

Question 81

What method is used to cause recipient females to become pseudopregnant?

Answer 81

copulation with vasectomized male

Question 82

What is backcrossing?

Answer 82

mating a chimera to a wild type

Question 83

What is oxytocin?

Answer 83

induces labor

Question 84

What is dystocia?

Answer 84

difficult labor

Question 85

What are Founders?

Answer 85

pups resulting from pronuclear injection

Question 86

What are chimeras?

Answer 86

pups produced by targeted-gene mutation

Question 87

True or False: In order to avoid disturbing the litter, the best time to genotype a mouse is within 2 days of birth.

Answer 87

False

Question 88

What are 2 reasons that cryopreservation can help ensure that mouse strains remain available and genetically unchanged?

Answer 88

repopulation a strain of animals if died/euthanized, it can be used to return to the original genetic make-up

Question 89

Embryos are obtained for cryopreservation by mating which type of female?

Answer 89

wild-type female

Question 90

What 2 conditions that could be responsible for the lack of offspring following a timed-mating?

Answer 90

sterility, embryonic lethality

Question 91

What describes a congenic strain?

Answer 91

the result of backcrossing for 10 generations

Question 92

True or False: CRISPR is a naturally occurring gene repair mechanism?

Answer 92

True