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Ruth Grace's Content

There have been 10 items by Ruth Grace (Search limited from 22-September 19)

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#146545 Re-culturing empty plasmid

Posted by Ruth Grace on 10 December 2012 - 11:50 PM in Molecular Biology

Greetings Posted Image

I am new in molecular biology lab. I was given an ecoli + empty pgsa plasmid and my sv ask me to reculture them.

My questions are:

1) What is an empty plasmid?
2) When I reculture them, my sv ask me to add antibiotics. What is the purpose of doing that?

Thank you for all the brilliant answers! :)

#139520 Malaysia Society for Microbiology Symposium 2012

Posted by Ruth Grace on 16 August 2012 - 12:31 AM in Conference and Workshop


This coming November, Biotechnology Research Institute, Universiti Malaysia Sabah (UMS), Malaysia will be organizing a Malaysia Society for Microbial Symposium 2012. The symposium will be held on 27-30 November 2012. Those who are interested to participate in the symposium, please drop your email here. Thank you! Posted Image

#138302 Change in the pH of stock solution

Posted by Ruth Grace on 25 July 2012 - 07:04 PM in General Lab Techniques

your problem is that the solutions are not buffered. co2 absorption will cause reduction of pH but if the solution warms up then co2 will desorb and you will experience an increase in pH.

you can add some buffer to the solutions to stabilize their pH.

Thank you for this opinion my friend. I'll have a try on this one. Just hope that the buffer doesn't affect the seaweed growth. Thank you again. :D

#138301 Change in the pH of stock solution

Posted by Ruth Grace on 25 July 2012 - 07:02 PM in General Lab Techniques

This is just off the top of my head, I've never worked with seaweed cultures.
Seawater might contain some organic material that continues to degrade and change the pH, or the chemicals in the seawater might react with each other over time and alter compostition, maybe also under light (transparent bottles?).
Whats the plant regulator exactly ? Depending on the chemical make up it may form or catalyze reactions with other chemicals present ?
Other than that, what Crazy Xabi said are excellent points.

You could try a test series without plant regulator to see if it's the reason for the pH change. Or filter the seawater to get rid of some organic components.
Good luck !

I'm using IAA for the hormone and I've autoclave the seawater earlier. The bottles are kept in the lab, in room temperature, so I wonder do light really do affect the pH? Anyway thank you for your opinion my friend. This is helpful :)

#138246 Change in the pH of stock solution

Posted by Ruth Grace on 25 July 2012 - 12:32 AM in General Lab Techniques

Some poorly buffered media may show a different pH when are stirred due to the CO2. Try to measure the pH both direct from the bottle and using the magnetic stirrer. If you notice a change, it's because of the air.

Did you autoclave after preparation? pH can change.

Also, some solutions, buffers and media may take a day to stabilize the pH, e.g. adjusting the pH of the Tris-HCl 1M requires initial pH adjustment and repeat it after 24h to get the desired stable pH value

Thank you for your opinion, pal. I did not autoclave the stock. Is it necessary to autoclave them?

#138238 Change in the pH of stock solution

Posted by Ruth Grace on 24 July 2012 - 06:35 PM in General Lab Techniques

Or just measuring inaccuracies? As in several threads here mentioned measuring the pH of water is quite tricky and small impurities (e.g. from the storage solution), differences in dissolved CO2, or calibration changes of the pH-meter lead to larger pH changes of the water or different measurements.

Not sure about the buffering capacities of seawater. Is there any?

Do CO2 or any gases will give big impact to the pH of the solution?

#138237 Change in the pH of stock solution

Posted by Ruth Grace on 24 July 2012 - 06:33 PM in General Lab Techniques

In my consideration there are 3 chances for this change.
1. did you really used the ddH2O? (unless cleaned apparatus during preparing solution?)
2. Proper covering of the solution as well as the Removing method(contamination of other solution).
3.The temp. of the solution where you keep them ( destroying the growth hormonesEx. indole group cleavage)
I think you used the pH meter per as std. protocol. so it is not the problem. these are just my opinions. don't hesitate to tell me the correct solution for your problem. good luck

Thank you so much for the opinion my friend. I use milliQ for the distilled water, so I guess there is no problem for that. And the solutions are prepared in reagents bottles and stored in the lab at room temperature. I can't think of any other factors that could lead to the change of pH. :(

#138183 Change in the pH of stock solution

Posted by Ruth Grace on 23 July 2012 - 08:18 PM in General Lab Techniques


I am currently doing an experiment on the pH optimization of seaweed culture. I have prepared 5 bottles of pH stock solution with different pH. Each of the stock contain autoclaved seawater, distilled water and plant growth regulator. After a few days, I realized that the pH of the stock changed. For example, the pH 5 will rise to pH 5.5. Is this normal? Or are there any factors that will cause the increase in the pH.

I appreciate every opinions. Thanks guys ;-)

#136868 Transformation of an inducible GFP gene into Aspergillus niger

Posted by Ruth Grace on 03 July 2012 - 05:35 PM in Genetics and Genomics

Thank you! :D

#136742 Transformation of an inducible GFP gene into Aspergillus niger

Posted by Ruth Grace on 01 July 2012 - 06:09 PM in Genetics and Genomics

Hello, I am doing the transformation of an inducible GFP gene into Aspergillus niger for my final year project. I am BSc student and looking for opinion on the best method to transform the GFP in A.niger (besides using Agrobacterium). Also, I would like to ask opinion on how to screen the transformed fungus. Thank you. Posted Image

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