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These are dead/dying cells. ANy population of cells will have a few.
#136661 Unknown floating substances in culture flask
Posted
on 29 June 2012 - 05:59 PM
#138310 Change in the pH of stock solution
Posted
on 26 July 2012 - 12:10 AM
Ruth Grace, on 25 July 2012 - 12:32 AM, said:
Thank you for your opinion, pal. I did not autoclave the stock. Is it necessary to autoclave them?
Don't know if it is necessary, but some solutions can change the pH before and after autoclaving
One msds of IAA (link) states that is light sensitive.
You say you autoclave the seawater before adding the IAA, but the IAA... is it sterile? Some bugs may hide in the IAA flask
#138248 Change in the pH of stock solution
Posted
on 25 July 2012 - 02:19 AM
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 !
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 !
#138256 Change in the pH of stock solution
Posted
on 25 July 2012 - 03:09 AM
"Boil the distillate for more than 15 minutes to expel carbon
dioxide, and cool in a container fitted with a carbon dioxide-absorbing tube (soda
lime). Store the pH standard solutions in hard glass or polyethylene bottles. As the
pH value may change during storage for a long period, usually use acidic standard
solutions within 3 months, and use basic standard solutions within 1 month under
storage in containers fitted with a carbon dioxide-absorbing tube (soda lime)." This is for normal Solution prepartions. But you are using Seawater which is full of minerals and salts. So it is obvious in change of pH very soon. I think u got it friend.
dioxide, and cool in a container fitted with a carbon dioxide-absorbing tube (soda
lime). Store the pH standard solutions in hard glass or polyethylene bottles. As the
pH value may change during storage for a long period, usually use acidic standard
solutions within 3 months, and use basic standard solutions within 1 month under
storage in containers fitted with a carbon dioxide-absorbing tube (soda lime)." This is for normal Solution prepartions. But you are using Seawater which is full of minerals and salts. So it is obvious in change of pH very soon. I think u got it friend.
#138261 Change in the pH of stock solution
Posted
on 25 July 2012 - 05:17 AM
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.
you can add some buffer to the solutions to stabilize their pH.
#138242 Change in the pH of stock solution
Posted
on 24 July 2012 - 09:59 PM
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
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
#138212 Change in the pH of stock solution
Posted
on 24 July 2012 - 09:16 AM
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?
Not sure about the buffering capacities of seawater. Is there any?
#138211 Change in the pH of stock solution
Posted
on 24 July 2012 - 08:54 AM
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
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
#136800 Transformation of an inducible GFP gene into Aspergillus niger
Posted
on 02 July 2012 - 01:14 PM
I don;t know about transformation of ungi, but I would probably invesitgate electroporation.
You should be able to screen by any one of the basic molecular methods such as PCR, western blotting, immuo-fluorescence or even if the cells are induced plain old GFP fluorescence.
You should be able to screen by any one of the basic molecular methods such as PCR, western blotting, immuo-fluorescence or even if the cells are induced plain old GFP fluorescence.
