Difference between revisions of "Team:Aachen/Lab/Glycogen/Characterization"
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After building our mono- and polycistronic constructs, their characterization was the next and possibly most important step. In this process, we investigated both cell growth and glycogen formation to prove the accumulation of glycogen due to the overexpression of glycogen building genes and the knockout of glycogen degradation genes. | After building our mono- and polycistronic constructs, their characterization was the next and possibly most important step. In this process, we investigated both cell growth and glycogen formation to prove the accumulation of glycogen due to the overexpression of glycogen building genes and the knockout of glycogen degradation genes. | ||
− | In our approaches, we wanted to examine the function of ''glgCAB'', draw conclusions on fermentation conditions and estimate the increase in glycogen. Therefore, we did growth experiments with ''Escherichia coli'' BL21 Gold (DE3) and analysed respective samples via [[Team:Aachen/Notebook/Protocols#Iodine_Staining|iodine staining]] and [[Team:Aachen/Notebook/Protocols#Dinitrosalicylic_Acid_Staining| dinitrosalicylic acid staining]]. Furthermore, we did glycogen purifications to apply a [[Team:Aachen/Notebook/Protocols#Glycogen_Kit|glycogen kit]]. | + | In our approaches, we wanted to examine the function of ''glgCAB'', draw conclusions on fermentation conditions and estimate the increase in glycogen. Therefore, we did growth experiments with ''Escherichia coli'' BL21 Gold (DE3) and analysed respective samples via [[Team:Aachen/Notebook/Protocols#Iodine_Staining|iodine staining]] and [[Team:Aachen/Notebook/Protocols#Dinitrosalicylic_Acid_Staining| dinitrosalicylic acid staining]]. Furthermore, we did glycogen purifications to apply a [[Team:Aachen/Notebook/Protocols#Glycogen_Kit|glycogen kit]]. |
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|[http://parts.igem.org/Part:BBa_K1585310 K1585310]|| ''glgA'' || characterized monocistronic BioBrick by iodine staining | |[http://parts.igem.org/Part:BBa_K1585310 K1585310]|| ''glgA'' || characterized monocistronic BioBrick by iodine staining | ||
|- | |- | ||
− | |[http://parts.igem.org/Part: | + | |[http://parts.igem.org/Part:BBa_K1585311 K1585311]|| ''glgB'' || characterized monocistronic BioBrick by dinitrosalicylic acid staining |
|- | |- | ||
|[http://parts.igem.org/Part:BBa_K1585351 K1585351]|| Δ''glgP'' || characterized gene knockout by iodine staining | |[http://parts.igem.org/Part:BBa_K1585351 K1585351]|| Δ''glgP'' || characterized gene knockout by iodine staining | ||
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− | + | The ''glgC'' BioBrick, based on BBa_K118016 by Team Edinburg 2008, was fused with the well-characterized RBS B0034. The dark color shows that the strong effect of GlgC on glycogen accumulation was preserved. | |
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=Dinitrosalicylic Acid Staining= | =Dinitrosalicylic Acid Staining= | ||
− | The iodine staining of strains containing ''glgB'' (branching enzyme) was not quite | + | The iodine staining of strains containing ''glgB'' (branching enzyme) was not quite distinct. We still wanted to investigate the functionality of the strains. Therefore, we used [[Team:Aachen/Notebook/Protocols#Dinitrosalicylic_Acid_Staining| dinitrosalicylic acid staining (DNS)]] for detection of reducing ends <ref>S. K. Meur, V. Sitakara Rao, and K. B. De. Spectrophotometric Estimation of Reducing Sugars by Variation of pH. Z. Anal. Chem. '''283''', 195-197 (1977)</ref> which should correspond to the branching frequency. All samples of ''glgB'' strains were compared to wild type samples. For best comparison the samples were grown to stationary phase and adjusted to the same OD before staining. Since every sugar or alkyl would have reacted with 3,5-dinitrosalicylic acid, we purified our samples before the staining. In order to identify the branching frequency, we analyzed the absorbance values of the purified samples compared to the absorbance values of hydrolyzed samples. By calculating the absorbance ratio of the non-hydrolyzed divided by the hydrolyzed samples, we aimed for information about the branches per glycogen unit. |
The reaction principle can be described as follows. | The reaction principle can be described as follows. | ||
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− | {{Team:Aachen/DoubleFigure|Aachen GlycogenDNSNotHydrolyzed.png|Aachen GlycogenDNSHydrolyzed.png|title1=DNS staining of non-hydrolyzed samples of the ''glgB'' strain and wild type|title2=DNS staining of hydrolyzed samples of the ''glgB'' strain and wild type|subtitle1=The non-hydrolyzed samples of the ''glgB'' strain and wild type show that the overexpression of ''glgB'' leads to glycogen molecules with a higher number of branches compared to the wild type. Error bars show propagation of uncertainty.|subtitle2=The hydrolyzed samples indicate that the glycogen amount is higher in the wild type compared to the ''glgB'' strain. Error bars show propagation of uncertainty. Since cell fragments are still left in the samples, the blank also shows an absorbance. Therefore, the line does not go though the origin.|size=medium}} | + | {{Team:Aachen/DoubleFigure|Aachen GlycogenDNSNotHydrolyzed.png|Aachen GlycogenDNSHydrolyzed.png|title1=DNS staining of non-hydrolyzed samples of the ''glgB'' strain and wild type|title2=DNS staining of hydrolyzed samples of the ''glgB'' strain and wild type|subtitle1=The non-hydrolyzed samples of the ''glgB'' strain and wild type show that the overexpression of ''glgB'' leads to glycogen molecules with a higher number of branches compared to the wild type. Error bars show propagation of uncertainty.|subtitle2=The hydrolyzed samples indicate that the glycogen amount is higher in the wild type compared to the ''glgB'' overexpressing strain. Error bars show propagation of uncertainty. Since cell fragments are still left in the samples, the blank also shows an absorbance. Therefore, the line does not go though the origin.|size=medium}} |
<span style="color:transparent">a</span> | <span style="color:transparent">a</span> | ||
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− | {{Team:Aachen/DoubleFigure|Aachen GlycogenDNSRatio.png|Aachen_GlycogenDNSCalibration.png|title1=ratio of non-hydrolyzed and hydrolyzed DNS staining values of the ''glgB'' strain and wild type|title2=glycogen calibration curve|subtitle1=Although the amount of glycogen is higher in the wild type (see figure above), the number of branches per glycogen unit is higher in the ''glgB'' strain. | + | {{Team:Aachen/DoubleFigure|Aachen GlycogenDNSRatio.png|Aachen_GlycogenDNSCalibration.png|title1=ratio of non-hydrolyzed and hydrolyzed DNS staining values of the ''glgB'' strain and wild type|title2=glycogen calibration curve|subtitle1=Although the amount of glycogen is higher in the wild type (see figure above), the number of branches per glycogen unit is higher in the ''glgB'' overexpressing strain. Therefore the overexpression of ''glgB'' successfully increased the number of branches. Error bars show propagation of uncertainty.|subtitle2=With the calibration curve we are able to identify the glycogen concentration of our samples. Error bars show propagation of uncertainty.|size=medium}} |
<span style="color:transparent">a</span> | <span style="color:transparent">a</span> |
Latest revision as of 03:49, 19 September 2015