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Special Series: Manuscript Tips—Abstract Writing Part 2: Too Much Too Soon?

Nathan S. Blow, PhD

How much information should be in my Abstract? Find out...

In the second installment of our summer manuscript tip series, we again focus our attention on the Abstract, asking: How much information is too much? This is an important question writers are often faced with, since most journals place a specific word count limit (generally 150-200 words) on Abstracts. Today’s column will focus on a few simple tips to help you keep everything you need while eliminating those parts that might not add to your narrative.

Can an entire manuscript be summarized in 200 words or less? When faced with this question, researchers often go one of two ways: either they decide that they can’t fit in all of the critical information and forgo working through the Abstract altogether, simply copying lines from the main text (not a good idea), or they waste precious time deciding what to cut and what to keep.

Often, we see the incorporation of numerous specific details on the methods and data in the Abstract. While this information may be important, only the most critical data and methods should be featured in the Abstract—everything else should be summarized for the reader as succinctly as possible.

Let’s go through an example of an Abstract with too much data and discuss how this might be corrected:

Version 1

“shRNA-mediated knockdown or inhibition of the enzyme by the anti-convulsive drug gabapentin led to decreased proliferation in vitro as well as 3-fold up-regulation of CDK1 expression and 1/3 increase in the fraction of cells in the G1 phase of the cell cycle. Enzyme inhibition by gabapentin also resulted in a 1.65-fold intracellular accumulation of free amino acids and the reduction of glutamate secretion by 6.35%, both of which are known to promote growth and invasiveness.”

Here we have two sentences from a hypothetical Abstract. Reading these sentences, one is left to wonder whether all of the data mentioned are critical to the major point the author is attempting to make. In many instances, such specific wording can take away from the overall message.

The sentences should concisely convey the important data in the study, leading into a statement of the major results and conclusions of the study in the “Here we show...” sentence I discussed in the first installment of this series. But could there be too much information for the reader at this stage?

Let’s do some revision here:

Version 2

"Reduced expression of the enzyme led to decreased cell proliferation in vitro, up-regulation of CDK1 and an increased fraction of cells in the G1 phase of the cell cycle. Enzyme inhibition also led to intracellular accumulation of amino acids and reduced glutamate secretion, both of which are known to promote growth and invasiveness."

What I hope you can begin to appreciate is that the specifics mentioned in the first version, although absent from the second, are not really missed in the Abstract. It is true that some mention of the methods used to reduce enzyme expression could be added back to the sentence; however, when dealing with a word count limit, it is important to provide the reader with only those details necessary to convey the overall significance of the study.

In our example, the exact percent decreases in enzyme expression and activity are not critical at this stage, only the fact that these changes were functionally or statistically significant. The manner in which expression was reduced is also not critical at this point (unless this is a new method or technique)—the use of shRNA to knock down expression will be described in the methods and results sections. What resulted from these knockdown experiments is, however, important for our understanding of the study’s implications. Support for these findings (i.e., the numerical data) will come in the main text of the manuscript, where the data will be described in detail and rigorously examined to support the conclusions of the manuscript.

Remember, your Abstract is a synopsis of the article and should therefore provide the most relevant details in as straightforward fashion as possible.

Now, we make a few minor edits to improve clarity and concision:

Version 3

"Reduced expression of the enzyme decreases cell proliferation in vitro, up-regulates CDK1 and increases the fraction of cells in the G1 phase. Enzyme inhibition also leads to intracellular accumulation of amino acids and reduced glutamate secretion, both of which are known to promote growth and invasiveness."

We arrive at our final product, reducing the word count from 75 to 46 for the two sentences. If you compare the initial and final versions, it becomes clear that, while many specific details have been omitted, the overall meaning remains the same.

Such detailed pruning efforts should also be applied to the entire Abstract, particularly the first few sentences where authors often provide a rationale for their study. The rationale should also be direct and clear without reference to large numbers of previous studies or excessive descriptions of prior data. The challenge of an Abstract is to tell the story of your research in 200 words (or less), so you should always keep in mind that each word and sentence should serve a specific purpose in communicating your message to the reader—if it doesn’t, then don’t be afraid to hit the “delete” key.

In the next column, we will turn our attention to the Introduction section.

Keywords:  science writing