Neurogenetics

Question 1

What type of two mutations needs be introduce to a single mouse to obtain conditional
gene knockout?

Answer 1

Cre-recombinase and Lox P

Cre-recombinase attaches to Lox sequences between Lox P sites and Lox sequences are recombined by Cre recombinase

Question 2

What is the consequence of CA1-specific NMDA Receptor gene deletion

Answer 2

CA1- NR1 K.O mice show a deficient performance on spatial memory task

These mice did not show LTP in CA1 and showed impaired spatial memory whereas nonspatial forms of memory remained intact

Question 3

What is the consequence of CA3-specific NMDA Receptor gene deletion

Answer 3

Abnormal learning on spatial navigation (w/ partial spatial cues) tasks such as Morris Water Maze

Produced mice that could acquire and retrieve spatial memories as well as wild type animals but suffered from significant deficits in retrieving these memories if presented with only a subset of original visual cues. Moreover these mice had normal CA1 place fields under full-cue task conditions but decreased place cell specificity under partial- cue conditions

Conclusion: CA3 NMDAR are important for spatial memory

Question 4

What is the consequence of Dentate Gyrus -specific NMDA Receptor gene deletion?

Answer 4

These mice performed normally on a contextual fear-conditoning task, but were impaired at differentiating between two similar contexts

Conclusion: DG NMDRs are important for the discrimination of similar context

Question 5

Transgene

Answer 5

Gene that has been transferred from one organism to another by number of genetic engineering techniques

Question 6

Transgenic mice

Answer 6

Overexpress the foreign genes within their bodies with characteristics patterns of gene expression, which is determined by the gene promoter used in the transgene desgin

Question 7

Gene Knock-Out (KO)

Answer 7

• Non functional homolog of the gene is injected into the embryonic stem cell
• the inactivated gene replaces the endogenous gene
• the stem cell is implanted into the embryo of another mouse
• their offspring will no longer have that gene (knockout)
• embryonic death can occur which prevents studying the adult

Question 8

Gene Knock-in (K.In.)

Answer 8

substitution of one specific DNA sequence w/ another

insertion of new dna sequence

Question 9

Conditional Gene Knock-out (cK.O)

Answer 9

Technique used to eliminate a specific gene in a certain tissue. w/ this technology scientists are able to knock out genes at a specific stage in development and study how the knockout of a gene in one tissue affects the same gene in other tissue. Cre Lox recombination system is the most technique

Question 10

Cre recombinase

Answer 10

An enzyme from P1 bacteriophage that catalyzes site-specific recombination f DNA between loxP sites

Question 11

What are potential problems with general gene knockout (K.O.)?

Answer 11

Developmental defects

Mutations are not anatomically restricted

Introduced mutation can cause irreversible alteration to neural network

Question 12

What are advantages of Conditional Gene Knock-out (cK.O.)? CRE-Lox recombination system

Answer 12

Anatomically restricted. can be accomplished by viral-mediated gene transfer (virus injection to CA1 region in hippocampus ) or by taking advantage of specific gene promoters driving expression into specific brain regions

Cre-Lox based cK.O. provides very effective control for potential developmental defects

Question 13

Cre LoxP system

Answer 13

used to carry out deletions, insertions, translocations, and inversions at specific sites in the DNA

Question 14

Advantage of Cre LoxP

Answer 14

can be controlled spatiotemporally