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Example 2 - Gel photograph

Study the gel photograph below and answer the questions that follow. Once you have entered your thoughts in the box provided click on the 'Check your answer' button to see a suggested answer.

Figure 2: Quantification of pET23a plasmid DNA. 5μg of pET23a plasmid DNA was restricted with enzyme HindIII (30U) and run on a 1.0% agarose gel to quantify DNA concentration. Samples loaded are: DNA ladder (10, 5 and 2μl), uncut pET23a (2μl) and restricted pET23a DNA (2μl and 10μl). DNA was quantified as 100ng/μl.

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Questions:

1. Is the figure sufficiently annotated?
2. Is the legend sufficient to make the data comprehensible to the reader without having to refer to the main text of the article?

The figure is not adequately labelled. The photograph should be annotated so that each lane on the gel is numbered 1, 2, 3, 4, etcetera. The band of interest should also be labelled with the name or the size.

Although, this figure has been assigned a number and includes a legend that explains the experiment, it is impossible to follow which sample loadings relate to which lane on the gel photograph.

To improve the quality of this figure, it could be reproduced as below. If you study the re-designed figure, you will see that the lanes have been labelled and the significant band has been annotated on the photograph. In addition, the legend has bee expanded to include information on which sample loadings correlate with which gel lane on the photograph.

Figure 2: Quantification of pET23a plasmid DNA. 5μg of pET23a plasmid DNA (3.6Kb) was restricted with enzyme HindIII (30U) and run on a 1.0% agarose gel to quantify DNA concentration. Samples loaded are: Lanes 1-3: 1Kb DNA mass ladder (10, 5 and 2μl respectively), Lane 4: uncut pET23a (2μl) and Lanes 5-6: restricted pET23a DNA (2μl and 10μl respectively). DNA was quantified as 100ng/μl.

Check your answer