One wants to knock out gene A and gene B. One would mate A+/- X B+/-. what if gene A and gene B are on the same chromosome? Probably dumb question. Thanks.
我自己从来没试过,我问过我老板完全相同的问题 我记得我老板跟我说,gene A and B 在同一个chromosome上面的话,比较难cross 一般情况下,大家都会放弃,选择cross A 和 C, 比如 C gene是B的receptor,这样可 以解释同样的问题 如果A,B 在chromosome上面距离比较远,有可能 重组 成功,但是 需要一定的工作量 如果A,B的gene位置比较近,举个例子,P38MAPK的alpha, beta (MAPK 11,12,13,14) 。。。。 他们隔得非常近 位于同一个locus,所以 一直没有很好的triple KO, quart KO model 所以说,crispr很强大呀!
l*z
10 楼
去爬小黑的楼吧。。
H*e
11 楼
Bless
s*9
12 楼
Thanks for the reply. But in pratice, if one has to do this. What I can think of are: 1) as you said, hoping the homologous recombination during meiosis. 2) get a B+/- allele in A+/- background? 50% chance it would be on the same chromosome. Just don't know what people actually do in reality. BTW, one pertinent questtion, when one makes transgenic mouse, is it routine to pinpoint the integration site? (People often cross a transgenic mouse with a KO mouse or transgenic mouse) Especially for Cre-transgenic mouse, people use them to cross with all kinds of LoxP-KO. The chance of CRE and LoxP on the same chromosome would be inevitable for certain genes? THanks.
quart
【在 r******g 的大作中提到】 : 我自己从来没试过,我问过我老板完全相同的问题 : 我记得我老板跟我说,gene A and B 在同一个chromosome上面的话,比较难cross : 一般情况下,大家都会放弃,选择cross A 和 C, 比如 C gene是B的receptor,这样可 : 以解释同样的问题 : 如果A,B 在chromosome上面距离比较远,有可能 重组 成功,但是 需要一定的工作量 : 如果A,B的gene位置比较近,举个例子,P38MAPK的alpha, beta (MAPK 11,12,13,14) : 。。。。 他们隔得非常近 位于同一个locus,所以 一直没有很好的triple KO, quart : KO model : 所以说,crispr很强大呀!
d*a
13 楼
尘螨过敏的话,儿医是建议去掉地毯,换成地板,被子床单都用一种隔离的COVER.
f*e
14 楼
啊?!Bless!
a*a
15 楼
primary culture mouse A-/- ES
quart
【在 r******g 的大作中提到】 : 我自己从来没试过,我问过我老板完全相同的问题 : 我记得我老板跟我说,gene A and B 在同一个chromosome上面的话,比较难cross : 一般情况下,大家都会放弃,选择cross A 和 C, 比如 C gene是B的receptor,这样可 : 以解释同样的问题 : 如果A,B 在chromosome上面距离比较远,有可能 重组 成功,但是 需要一定的工作量 : 如果A,B的gene位置比较近,举个例子,P38MAPK的alpha, beta (MAPK 11,12,13,14) : 。。。。 他们隔得非常近 位于同一个locus,所以 一直没有很好的triple KO, quart : KO model : 所以说,crispr很强大呀!
【在 s********9 的大作中提到】 : Thanks for the reply. : But in pratice, if one has to do this. What I can think of are: : 1) as you said, hoping the homologous recombination during meiosis. : 2) get a B+/- allele in A+/- background? 50% chance it would be on the same : chromosome. : Just don't know what people actually do in reality. : BTW, one pertinent questtion, when one makes transgenic mouse, is it routine : to pinpoint the integration site? (People often cross a transgenic mouse : with a KO mouse or transgenic mouse) : Especially for Cre-transgenic mouse, people use them to cross with all kinds
I simply brought this up out of curiosity for discussion. I have NO hands-on experience with mouse genetics whatsoever. For double KO. the chance gene A and B on the same chromosome would be 1/20. People have done so many double KO. I figure this could be a practical issue. For crossing CRE-transgenic mouse with LoxP mouse to produce tissue-specific KO. The chance are also 1/20 the CRE-transgene and your LoxP-cassette being on the same chromosome. I don't think it's necessary impossible to achieve. One could always get a ES cell with A KO, then get B KO allele on top of this. Just wonder whether there are other options. BTW, for those CRE-transgenic mouse, do we know the integration site and copy number? Many many thanks.
In most cases, when the two genes are far enough away from each other, it is not a problem to generate the double null. However, when the two genes are very close to each other, it will be very hard to create the double null by just crossing the two single KOs; you may have to knockout the two genes in the same es cell to generate the mouse. Anybody who has taken a genetics course should know the underlying mechanism (hint: this has to do with what happens to the chromosomes during meiosis).
H*N
37 楼
You point regarding cre transgene and the floxed gene to be knocked out on the same chromosome is interesting. This can be a problem in practice. People don't always map the transgene. However, if you have a hard time getting the flox/flox;cre mouse, it is likely due to that the transgene and the gene of interest are closely located on the same chromosome.Of course, you still need to rule out embryonic lethality first.
same routine kinds
【在 s********9 的大作中提到】 : Thanks for the reply. : But in pratice, if one has to do this. What I can think of are: : 1) as you said, hoping the homologous recombination during meiosis. : 2) get a B+/- allele in A+/- background? 50% chance it would be on the same : chromosome. : Just don't know what people actually do in reality. : BTW, one pertinent questtion, when one makes transgenic mouse, is it routine : to pinpoint the integration site? (People often cross a transgenic mouse : with a KO mouse or transgenic mouse) : Especially for Cre-transgenic mouse, people use them to cross with all kinds
s*9
38 楼
Very informative. I cannot believe people don't know where the cre is when starting the crossing. Thanks a lot.
and
【在 H****N 的大作中提到】 : You point regarding cre transgene and the floxed gene to be knocked out on : the same chromosome is interesting. This can be a problem in practice. : People don't always map the transgene. However, if you have a hard time : getting the flox/flox;cre mouse, it is likely due to that the transgene and : the gene of interest are closely located on the same chromosome.Of course, : you still need to rule out embryonic lethality first. : : same : routine : kinds
s*9
39 楼
Plus, just for discussion, if gene A and B are near the two opposite telomeres on a certain long chromosome (as far as it can be), what kind of chance would you expect? (This expectation would be critical when you set up the crossing, right?)
is are by in what
【在 H****N 的大作中提到】 : In most cases, when the two genes are far enough away from each other, it is : not a problem to generate the double null. However, when the two genes are : very close to each other, it will be very hard to create the double null by : just crossing the two single KOs; you may have to knockout the two genes in : the same es cell to generate the mouse. Anybody who has taken a genetics : course should know the underlying mechanism (hint: this has to do with what : happens to the chromosomes during meiosis).
H*N
40 楼
The efficiency should be the same as you would expect with the two genes on different chromosomes.