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Are you using good quality [url="[url]http://www.alkaliscientific.com/en/filter-pipette-tips/637-a-barrier-tips.html"]filter[/url] tips[/url] when loading your samples? I found a lot of contamination issues were simply from the plastics I was using. Try the A+ Barrier Tips from Alkali Scientific... they are relativiely inexpensive and they work great.
#115278 problem in pcr
Posted
on 16 July 2011 - 07:23 PM
#115272 PCR Contamination issues
Posted
on 16 July 2011 - 07:03 PM
If you are using the 8-strip PCR tubes, their is a lot of cross contamination issues because of the lid. Try using these [url="[url]http://www.alkaliscientific.com/en/pcr-test-tube/316-pcr-tube-8-strip.html"]PCR[/url] tubes[/url] with individually attached caps. They prevent splashing the solution around causing cross-contamination. Plus, you can cut them.
#115270 Gel electrophoresis
Posted
on 16 July 2011 - 06:58 PM
I found an awesome new way to cut my gels.. Instead of hassling with a potentially non-sterile razor blade I use these disposable [url="[url]http://www.alkaliscientific.com/en/accessories/24-science-tool.html"]X-tracta[/url][/url] tools and its 10x easier.
#115222 Stacking gel for DNA PAGE
Posted
on 16 July 2011 - 05:26 AM
coldlab, on 01 July 2011 - 05:59 PM, said:
I am using 6% native PAGE to resolve 200-400bp DNA. I am getting a lot of smear especially when the volume of the sample is high. Does anybody make stacking gel for running DNA on PAGE?
#114962 Primer 3' mismatch
Posted
on 13 July 2011 - 06:55 AM
Yes, one nucleotide mismatch may not be enough. Two is better. Did you try increasing the temperature up to the point were mismatch wouldn't be amplified and match will? Sometimes temperature difference between melting of match and mismatch can be very narrow, you can try LNA spiked primers that have higher temperature differences.
#114185 Gene on negative strand - two eductional questions.
Posted
on 04 July 2011 - 07:44 AM
(+) and (-) are arbitrary denominations of DNA strands. Only direction that makes sense is the mRNA (or other functional RNAs, but that's virtually the same), that is single-stranded and translated to protein in the defined order. I would logically expect naming the gDNA strands with respect to that. So, (+) have the same sequence as mRNA (= coding strand), so the mRNA is created with (-) strand as a template. Problem now is in the fact that mRNAs can be in both directions, but of course whole strand on one chromosome must be either (+) or (-). Someone had to decide which one.
Historically, some gDNA was sequenced and published from one direction, the other one from other, presumably in respect for mRNA it creates. But after Human Genome Project was finished and aligned, all single gene gDNA entries were replaced by whole chromosome reads and as I wrote one strand must be always (+) and the other (-) even when (+) is not a coding strand for some of the mRNAs. This make some of the mRNAs to be from (-) strand.
This may aswer your first question, NCBI must have both strands in database (like for BLAST search) because each strand is the coding one for some mRNAs. I hope second question was also answered above.
Historically, some gDNA was sequenced and published from one direction, the other one from other, presumably in respect for mRNA it creates. But after Human Genome Project was finished and aligned, all single gene gDNA entries were replaced by whole chromosome reads and as I wrote one strand must be always (+) and the other (-) even when (+) is not a coding strand for some of the mRNAs. This make some of the mRNAs to be from (-) strand.
This may aswer your first question, NCBI must have both strands in database (like for BLAST search) because each strand is the coding one for some mRNAs. I hope second question was also answered above.
#113899 strange and branch like bands on SDS-PAGE
Posted
on 30 June 2011 - 06:15 AM
Hi, i have run many SDS-PAGES during working on my projects but recently I faced a problem.to check the purity of a recombinant peptide I am loading that after purification with Ni-NTA but after staing the gel all bands are duiffused and in so strange shape. There are no sharp bands and just bands like branches!I tried to prepare all buffers freshly and also I run at 80V for the first layer and 120 for the second but stil I couldnot overcome. could you please help me in this case?
#111656 Incubating Western in primary for longer than 24 hours at 4C?
Posted
on 02 June 2011 - 09:56 AM
noodle, on 02 June 2011 - 06:46 AM, said:
casandra, on 01 June 2011 - 12:43 PM, said:
n.t., on 01 June 2011 - 11:41 AM, said:
Is it acceptable to incubate membranes in your primary antibody dilution (5% Milk, 1x PBS, 0.1% Tween) for 48 hours at 4C, rather than the usual 24h? I wanted to decrease the amount of antibody used at a given time and I was curious if providing a longer incubation period would work.
Thank you!
Thank you!
Would reducing the typical amount of antibody used, (going from 1:500 to 1:1000 help to eliminate background for an extended incubation time?
#111121 PCRing small region on genomic DNA
Posted
on 27 May 2011 - 12:11 PM
HRM amplicons are recomended to be small but not that small. 100 - 200 bp is OK, you may have more problems with amplicon as short as 67 bp. It may be difficult to sequence such small fragment, 30 - 40 bp are usually lost at the beggining and you maybe wouldn't be able to get a clear read up to the end.
If you're not sure what are you amplifying, then your primers may just have wrong sequence and that's the reason why you can't see anything on the gel.
If you're not sure what are you amplifying, then your primers may just have wrong sequence and that's the reason why you can't see anything on the gel.
#109043 Blood
Posted
on 06 May 2011 - 06:42 AM
As apart of one of my biology classes assignment I had a dessertation to write on; whether or not a person who does not donate blood regularly or has never donated blood should they be offered blood at any given time of need. My answer is yes, for obvious reasons such as illnesses. Do you mind sharing your views on the situation?
#105003 Hi, you lab rats, take a break and watch this youtube piece
Posted
on 28 March 2011 - 10:12 AM
This is ridiculous. Very funny though.
Nettshop
Lage hjemmeside
Nettshop
Lage hjemmeside
genehunter, on 24 January 2011 - 03:28 PM, said:
#104075 Downside of dating a beauty: Doomed relationship
Posted
on 18 March 2011 - 08:37 AM
Just like Dr Hook warned in their 1979 hit, When You're In Love With A Beautiful Woman, research has revealed that relationships in which the woman is more attractive than the man may be doomed to failure.
However, having a handsome husband or boyfriend is no barrier to the couple's success, according to the study.
The phenomenon was spotted by British researchers who were studying whether it is true that we tend to pair up with those who are similarly attractive to ourselves.
Their findings could help explain why Angelina Jolie's marriages to actors Jonny Lee Miller and Billy Bob Thornton barely lasted three years a piece.
In contrast, her relationship with Brad Pitt, one of the world's most handsome celebrities, has already lasted six years, suggesting she has found her match.
The Stirling, Chester and Liverpool university researchers took photos of the men and women in more than 100 couples. Some had been together for just a few months, others for several years. The individual men and women were then rated on their looks.
The analysis revealed having an attractive husband or boyfriend was no barrier to a relationship succeeding. But, if it was the woman who was the one blessed with good looks, the relationships tended to last only a matter of months, the journal Personality and Social Psychology Bulletin reports.
Researcher Rob Burriss said: "This would indicate it is the woman who is in control of whether the relationship continues.
Beautiful women may realize they can afford to pick and choose, he suggests. They may also have the confidence to leave behind relationships that have run their course."
"Attractive women might generally prefer short-term relationships. They're better placed to move on."
It is also possible the relationships end due to jealous behavior from the woman's less photogenic partner.
Conversely, the less attractive women "may have to make do with what they have, hence the longer relationships", he said.
The study also found we tend to pair up with people whose facial features have a similar level of symmetry - a sign of beauty - to our own.
Dr Burriss said: "Are all men trying to go out with Anne Hathaway or Angelina Jolie, or do you really want to be with someone at the same level of attractiveness as yourself? These findings suggest our ideal partner is one on our own kind of level."
However, having a handsome husband or boyfriend is no barrier to the couple's success, according to the study.
The phenomenon was spotted by British researchers who were studying whether it is true that we tend to pair up with those who are similarly attractive to ourselves.
Their findings could help explain why Angelina Jolie's marriages to actors Jonny Lee Miller and Billy Bob Thornton barely lasted three years a piece.
In contrast, her relationship with Brad Pitt, one of the world's most handsome celebrities, has already lasted six years, suggesting she has found her match.
The Stirling, Chester and Liverpool university researchers took photos of the men and women in more than 100 couples. Some had been together for just a few months, others for several years. The individual men and women were then rated on their looks.
The analysis revealed having an attractive husband or boyfriend was no barrier to a relationship succeeding. But, if it was the woman who was the one blessed with good looks, the relationships tended to last only a matter of months, the journal Personality and Social Psychology Bulletin reports.
Researcher Rob Burriss said: "This would indicate it is the woman who is in control of whether the relationship continues.
Beautiful women may realize they can afford to pick and choose, he suggests. They may also have the confidence to leave behind relationships that have run their course."
"Attractive women might generally prefer short-term relationships. They're better placed to move on."
It is also possible the relationships end due to jealous behavior from the woman's less photogenic partner.
Conversely, the less attractive women "may have to make do with what they have, hence the longer relationships", he said.
The study also found we tend to pair up with people whose facial features have a similar level of symmetry - a sign of beauty - to our own.
Dr Burriss said: "Are all men trying to go out with Anne Hathaway or Angelina Jolie, or do you really want to be with someone at the same level of attractiveness as yourself? These findings suggest our ideal partner is one on our own kind of level."
#102786 post hoc test LSD for multiple comarisions
Posted
on 05 March 2011 - 03:23 AM
Hi there,
Two things, LSD is not a great post-hoc test. It is prone to false positives. At the very least you should do a protected LSD, or even better, a Tukey HSD test.
2) The answer is no on the comparison. The only way you can make the statement that the preventative was better than the curative is if you compare them directly to each other via the post-hoc. Based on the information you've given us you can only say that they are both better than the control group. You might be able to say there is a "trend" towards a greater effect in one versus the other, but unless the direct comparison is significant you really can't say anything.
MM
Two things, LSD is not a great post-hoc test. It is prone to false positives. At the very least you should do a protected LSD, or even better, a Tukey HSD test.
2) The answer is no on the comparison. The only way you can make the statement that the preventative was better than the curative is if you compare them directly to each other via the post-hoc. Based on the information you've given us you can only say that they are both better than the control group. You might be able to say there is a "trend" towards a greater effect in one versus the other, but unless the direct comparison is significant you really can't say anything.
MM
#99337 Micropipetting basics?
Posted
on 02 February 2011 - 12:59 AM
The only way to improve your technique is the old tried and tested way......
Sit down for an hour and practice your pipetting ONTO A PRECISION BALANCE.
You will instantly see with your own eyes IF you have pipetted the correct amount.
It is very important to do this as you can improve:
PRECISION AND ACCURACY.
This is an imperative skill to master as experimentation is dependent upon both of these skills.
Hope this is useful......there are no short cuts to excellence.
Kindest regards
Uncle Rhombus (34 years in the Lab)
Sit down for an hour and practice your pipetting ONTO A PRECISION BALANCE.
You will instantly see with your own eyes IF you have pipetted the correct amount.
It is very important to do this as you can improve:
PRECISION AND ACCURACY.
This is an imperative skill to master as experimentation is dependent upon both of these skills.
Hope this is useful......there are no short cuts to excellence.
Kindest regards
Uncle Rhombus (34 years in the Lab)
#99027 Solve puzzles for Science
Posted
on 30 January 2011 - 05:26 AM
For all the gambling addicts, protein scientists and people who have sufficient time and like it to play, but also like it to help scientists dealing with protein folding issues:
FOLDIT
FoldIt is a game in which humans try to solve one of the hardest computational problems in biology: protein folding. You don't need to know anything about biology to play the game, although a little background will help. Download the software, install it and play.
The application displays a graphical representation of the protein's structure which the user is able to manipulate with a set of tools.
As the structure is modified, a "score" is calculated based on how well-folded the protein is, and a list of high scores for each puzzle is maintained. Foldit users may create and join groups, and share puzzle solutions with each other; a separate list of group high scores is maintained.
Example image of the game interface:
FOLDIT
FoldIt is a game in which humans try to solve one of the hardest computational problems in biology: protein folding. You don't need to know anything about biology to play the game, although a little background will help. Download the software, install it and play.
The application displays a graphical representation of the protein's structure which the user is able to manipulate with a set of tools.
As the structure is modified, a "score" is calculated based on how well-folded the protein is, and a list of high scores for each puzzle is maintained. Foldit users may create and join groups, and share puzzle solutions with each other; a separate list of group high scores is maintained.
Example image of the game interface:
