Experimental Model Flashcards

1
Q

How were early mutations induced in zebrafish? What are examples of these mutations? Why were these mutations important?

A

Gamma ray irradiation. No tail (ntl), spadetail (spt), and cyclops. Discovery of ntl mutation disrupted an ortholog of the mouse brachyury (T) gene, providing evidence that homologous genes perform common functions and discoveries made in ZF could translate to other vertebrate models, including mammals.

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2
Q

What chemical is used to induce mutations in ZF?

A

N-ethyl-N-nitrosourea (ENU)

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3
Q

How many fertilized eggs can breeding adults produce from a single weekly spawning?

A

Up to 200 or more.

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4
Q

At what age do embryos acquire a fishlike appearance?

A

After 24h, when they have specified all three axes, possess a patterned rudimentary neural tube and eyes, and twitch spontaneously.

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5
Q

When does the first cleavage occur after fertilization? The subsequent cleavages?

A

After 45 minutes. Subsequent eight take place at 15-minute intervals.

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6
Q

What marks the onset of midblastula transition? When does this occur? What is an important aspect of this transition?

A

After the ninth cleavage, when the cell cycle begins to lengthen and cell divisions become asynchronous. 3 HPF. Activation of zygotic transcription - all processes up to that point are regulated by maternal factors deposited in egg

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7
Q

What is gastrulation? When does this start and when is it complete?

A

Process by which endoderm, mesoderm, and ectoderm take up final positions in embryo. Begins at 5.5 HPF and is complete at 10 HPF.

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8
Q

When do embryo cells begin to spread down over the yolk? What is this process called? When is it complete?

A

4.5 HPF. Termed epiboly. Complete at 10 HPF.

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9
Q

What occurs during 10 and 24 HPF?

A

Internal organs begin to form and morphological landmarks that preview adult structures become detectable.

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10
Q

Exposure of ZF to ENU most commonly induces what type of tumor?

A

Epidermal papillomas

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11
Q

The c-myc oncogene expressed in the ZF thymus using the rag2 promoter causes transgenic animals to develop what cancer?

A

T-cell acute lymphoblastic leukemia.

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12
Q

A model of what cancer was developed in ZF with expression of an oncogenic form of BRAF and loss of function allele of p53?

A

Melanoma

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13
Q

Mutations in the ZF ortholog of what gene leads to progressive degeneration of muscle fibers?

A

Dystrophin

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14
Q

What tissue in the ZF is studied due to its regeneration potential? How long does it take to regenerate? What is another, less commonly used organ for regeneration studies?

A

Fin. Regenerates over 10-12 day period. Within 1-2 days a regenerative blastema forms at the injury site and begins to proliferate. The heart.

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15
Q

Where can hair cells be found in ZF? What is unique about their response to damage?

A

Ear and lateral line. Regenerate within 2 days.

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16
Q

What type of mutations does ENU induce compared to radiation?

A

Individual nucleotide point mutations or small deletions, as compared to large-scale chromosomal rearrangements.

17
Q

How is ENU used to induce mutations in ZF?

A

Males immersed in ENU for a short period of time for several days so that mutations become fixed in germline after several weeks. Males generate F1 generation. Phenotypic scoring in embryonic F3 generation.

18
Q

How are haploid embryos developed? Do they survive? What is their function? How can they be made diploid?

A

Eggs from F1 female collected and fertilized with UV-irradiated sterile sperm. F2 embryos develop only from maternal component. Eventually lethal with circulatory problems, but screening for early phenotypes affecting embryonic decisions is possible. Made diploid via use of early pressure or heat shock to prevent meiotic/mitotic division.

19
Q

What do morpholino antisense oligonucleotides do? How are they administered? What is a drawback?

A

Direct the knockdown of a particular gene by disrupting protein translation of transcriptional splicing. Injected into fertilized embryos. Diluted with every cell division, resulting in weaker knockdown efficiencies in later stage larvae.

20
Q

When are zebrafish embryos injected with CRISPER? What does this result in?

A

Injected with cas9/RNA combo resulting in mosaic animals at the particular locus at the 1-4 cell stage. Breeding produces F1 animals heterozygous for the targeted mutation.