This set of Marine Biotechnology Question Bank focuses on “Transgenic Technology in Marine Organisms – Set 2”.
1. Chorion hardening in such fish species as rainbow trout can be prevented by using ____________
a) acetone
b) glutathione
c) butanol
d) alcohol
View Answer
Explanation: Microinjection in some fish such as rainbow trout and Atlantic salmon is difficult because of hardened chorions precluding the insertion of micro-needles. This can be avoided by initiating fertilization of collected eggs and sperms in 1 mM glutathione.
2. Intact chorion is not required for electroporation.
a) True
b) False
View Answer
Explanation: Electroporation is a method of creating transgenic marine organisms by using brief electric pulses to create pores in the cellular membranes. Unlike microinjection, intact chorion does not preclude delivery of foreign DNA.
3. Dilution of dry sperm with aqueous fluids leads to ____________
a) inactivation
b) activation
c) shrinking
d) chorion loss
View Answer
Explanation: Successful transfer of transgenes by electroporation sperm instead of embryos has been reported in the literature. The dry sperm remains un-activated in presence of 100% seminal fluid, dilution with aqueous buffers activates the sperms for a brief 30 seconds period.
4. Out of the activation window, the sperm cells are _____________
a) non-motile
b) motile
c) activated
d) fertilized
View Answer
Explanation: Out of the brief activation window that results after dilution with aqueous buffers, the sperm cells are rendered non-motile and incapable of fertilizing the eggs. The dilution with buffers therefore has to be made carefully to avoid any activation.
5. Which is the appropriate cell stage for efficient gene delivery by electroporation?
a) 1-2 cells
b) 20 cells
c) 100 cells
d) 1000 cells
View Answer
Explanation: 1-2 cell stage of the embryo is a pre-requisite for efficient delivery of transgene through direct microinjection and/or electroporation. Sperm-mediated transgene delivery is opted for in cases where multi-stage embryos are spawned.
6. Which is not a part of characterization of transgenic marine organisms?
a) Identifying presence of transgene
b) Expression of transgene
c) Integration of transgene
d) Choice of reporter gene
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Explanation: After successful delivery of transgene the marine organisms are characterized by identification of presence of the transgene, its expression and integration into the host genome. Choice of reporter gene is a preliminary step and is done before introduction of the foreign gene.
7. PCR amplification of the transgene sequence does not __________
a) differentiate between extrachromosomal unit
b) involve sequence specific primers
c) leads to a high copy number of genes
d) give high efficiency results
View Answer
Explanation: Polymerase chain reaction (PCR) and subsequent southern blot analysis is used to analyze the presence of a transgene. However the technique does not differentiate between chromosomal or extrachromosomal integration.
8. Following transfer of linearized/ circular transgene to fish embryos ___________
a) transgene remain as extrachromosomal unit
b) transgenes are degraded
c) transgenes are activated
d) transgenes get immediately integrated into the genome
View Answer
Explanation: After transfer of the transgenic construct into fish embryos they remain as extrachromosomal unit till the early phase of embryonic development. At a later stage some of the transgenes are randomly integrated into the genome.
9. Which is an absolute requirement for establishment of a transgenic fish line?
a) Small-sized fish
b) Large-sized fish
c) Flow cytometry
d) Integration of transgenes
View Answer
Explanation: For successful vertical transmission to subsequent generations and establishment of a transgenic fish line, it is extremely important that the transgenes be stably integrated in the fish genome.
10. Which is not used as an assay to detect transgene expression in fish?
a) RT-PCR
b) RNA northern blot
c) Immunoblotting
d) HPLC
View Answer
Explanation: High performance liquid chromatography (HPLC) is a type of column chromatography used in analytical chemistry to identify, quantify and purify a mixture of compounds. HPLC is not related to genetic studies.
11. RT-PCR requires a small amount of sample.
a) True
b) False
View Answer
Explanation: Reverse transcription – PCR is a very sensitive method to detect transgene expression, requiring a very small amount of sample. The preliminary step is total RNA isolation and subsequent synthesis of cDNA.
12. With respect to a transgene, homozygous lines can be produced by ___________
a) UV mutation
b) Benzene treatment
c) Glutathione treatment
d) Self-crossing heterozygous individuals
View Answer
Explanation: All transgenic individuals are heterozygous with respect to the transgene. To maintain a homozygous population (for maintenance of broodstock) the heterozygous individuals are self-crossed.
13. In the technique of androgenesis in rainbow trout, eggs from ___________ are irradiated.
a) founder population
b) progeny 1
c) non-transgenic females
d) transgenic females
View Answer
Explanation: The technique of androgenesis was developed for rainbow trout by Parsons and Thorgaard. The strategy is to irradiate eggs from non-transgenic fish (for nuclei inactivation) and fertilize them with sperm from the heterozygous transgenic fish.
14. Transgenic fish technology is an alternative to ___________
a) genetic selection using cross-breeding
b) vaccination
c) ornamental fish
d) aquaculture
View Answer
Explanation: Infectious disease outbreaks are one of the most severe bottlenecks in aquaculture. Ways to preclude these are vaccination and genetic selection using conventional cross-breading, transgenic fish technology is an alternate to the latter.
15. Which is the most suitable target for manipulating to confer disease resistance in fish?
a) β-actin
b) AMP
c) Hsp 70A
d) Hsp 70B
View Answer
Explanation: Upon attack by various pathogens, the innate immune system of fish release antimicrobial peptides as part of defense mechanism. The gene that encodes for these peptides can be manipulated to confer the host with a more efficient defense mechanism.
Sanfoundry Global Education & Learning Series – Marine Biotechnology.
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