1. GENERAL PRINCIPLES
Many experienced editors loathe abbreviations. Some editors would prefer that they not be used at all, except for standard units of measurement and their Systeme International (SI) prefixes, for which all scientific journals allow abbreviations. Many journals also allow, without definition, such standard abbreviations as etc., et al., i.e., and e.g. (The abbreviations i.e. and e.g. are often misused; properly used, i.e. means “that is,” whereas e.g. means “for example.” Because these abbreviations are so often misused or misinterpreted, we favor avoiding them.) In your own writing, you would be wise to keep abbreviations to a minimum. The editor will look more kindly on your paper, and the readers of your paper will bless you forever. More preaching on this point should not be necessary because, by now, you yourself have no doubt come across undefined and indecipherable abbreviations in the literature. Just remember how annoyed you felt when you were faced with these conundrums, and join with us now in a vow never again to pollute the scientific literature with an undefined abbreviation.
The “how to” of using abbreviations is easy, because most journals use the same convention. When you plan to use an abbreviation, you introduce it by spelling out the word or term first, followed by the abbreviation within parentheses. The first sentence of the introduction of a paper might read: “Bacterial plasmids, as autonomously replicating deoxyribonucleic acid (DNA) molecules of modest size, are promising models for studying DNA replication and its control.”
The “when to” of using abbreviations is much more difficult. Several general guidelines might help.
First, generally do not use an abbreviation in the title of an article. Very few journals allow abbreviations in titles, and their use is strongly discouraged by the indexing and abstracting services. If the abbreviation is not standard, the literature retrieval services will have a difficult or impossible problem. Even if the abbreviation is standard, indexing and other probl ems arise. One major problem is that accepted abbreviations have a habit of changing; today’s abbreviations may be unrecognizable a few years from today. Comparison of certain abbreviations as listed in the various editions of the Council of Biology Editors Style Manual (which has now become Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers) emphasizes this point. Dramatic changes occur when the terminology itself changes. Students today could have trouble with the abbreviation DPN (which stands for “diphosphopyridine nucleotide”), because the name itself has changed to “nicotinamide adenine dinucleotide,” the abbreviation for which is NAD.
Abbreviations should almost never be used in the abstract. Only if you use the same name, a long one, many times should you consider an abbreviation. If you use an abbreviation, you must define it at the first use in the abstract. Remember that the abstract will stand alone in whichever abstracting databases cover the journal in which your paper appears.
In the text itself, abbreviations may be used if a long word or phrase will appear repeatedly. They serve a purpose in reducing printing costs, by somewhat shortening the paper. More importantly, they aid the reader when they are used judiciously. Speaking of “importantly”: We are reminded of a man whose children sometimes refer to him as “the FIP” (fairly important person). They know that he hasn’t yet made it to VIP.
2. GOOD PRACTICE
It can be advisable, when writing the first draft of the manuscript, to spell out all terms and phrases. Then examine the manuscript for repetition of long words or phrases that might be candidates for abbreviation. Do not abbreviate a term or phrase that is used only once or twice in the paper. If the term or phrase is used with modest frequency—for example, between three and six times—and a standard abbreviation for it exists, introduce and use the abbreviation. (Some journals allow some standard abbreviations to be used without definition at first use.) If no standard abbreviation exists, do not manufacture one unless the term or phrase is used frequently or is very long and cumbersome.
Often you can avoid abbreviations by using the appropriate pronoun (it, they, them) if the antecedent is clear. Another possibility is to use a substitute expression such as “the inhibitor,” “the substrate,” “the drug,” “the enzyme,” or “the acid.”
Usually, you should introduce your abbreviations one by one as they first occur in the text. Alternatively, you might consider a separate paragraph (headed “Abbreviations Used”) in the introduction or in the materials and methods section. The latter system (required in some journals) is especially useful if the names of related reagents, such as a group of organic chemicals, are to be used in abbreviated form l ater in the paper. Another option, for example in review papers and grant proposals, can be to include a table listing and defining abbreviations. Such tables make definitions easy to find even if a piece is not being read from beginning to end. Also, if chapters of a book might be read individually or in different orders, consider defining abbreviations on first appearance in each chapter. The same principle holds for other lengthy pieces of writing, such as long proposals, that might well be read other than from start to finish.
3. UNITS OF MEASUREMENT
Units of measurement are abbreviated when used with numerical values. You would write “4 mg was added.” (The same abbreviation is used for the singular and the plural.) When used without numerals, however, units of measurement are not abbreviated. You would write “Specific activity is expressed as micrograms of adenosine triphosphate incorporated per milligram of protein per hour.”
Careless use of the diagonal can cause confusion. This probl em arises frequently in stating concentrations. If you say that “4 mg/ml of sodium sulfide was added,” what does this mean? Does it mean “per milliliter of sodium sulfide” (the literal translation) or can we safely assume that “per milliliter of reaction mixture” is meant? It is much clearer to write “4 mg of sodium sulfide was added per milliliter of medium.”
5. SPECIAL PROBLEMS
A frequent probl em with abbreviations concerns use of “a” or “an.” Should you write “a M.S. degree” or “an M.S. degree”? Recall the old rule that you use “a” with words beginning with a consonant sound and “an” with words beginning with a vowel sound (for example, the letter “em”). Because in science we should use only common abbreviations, those not needing to be spelled out in the reader’s mind, the proper choice of article should relate to the sound of the first letter of the abbreviation, not the sound of the first letter of the spelled- out term. Thus, although it is correct to write “a master of science degree,” it is incorrect to write “a M.S. degree.” Because the reader reads “M.S.” as “em ess,” the proper construction is “an M.S. degree.”
In biology, it is customary to abbreviate generic names of organisms after first use. At first use, you would spell out “Streptomyces griseus.” In later usage, you can abbreviate the genus name but not the specific epithet: S. griseus. Suppose, however, that you are writing a paper that concerns species of both Streptomyces and Staphylococcus. You would then spell out the genus names repeatedly. Otherwise, readers might be confused as to whether a particular “S.” abbreviation referred to one genus or the other.
6. SI (SYSTEME INTERNATIONAL) UNITS
Appendix 3 gives the abbreviations for the prefixes used with all Systeme International (SI) units. The SI units and symbols, and certain derived SI units, have become part of the language of science. This modern metric system should be mastered by all students of the sciences. Scientific Style and Format (Style Manual Subcommittee, Council of Science Editors 2014) is a good source for more complete information, as is Huth’s (1987) Medical Style and Format. Briefly, SI units include three classes of units: base units, supplementary units, and derived units. The seven base units that form the foundations of SI are the meter (or metre), kilogram, second, ampere, kelvin, mole, and candela. In addition to these seven base units, there are two supplementary units for plane and solid angles: the radian and steradian, respectively. Derived units are expressed algebraically in terms of base units or supplementary units. For some of the derived SI units, special names and symbols exist.
7. OTHER ABBREVIATIONS
Some style manuals in the sciences (for example, Iverson and others 2007; Style Manual Subcommittee, Council of Science Editors 2014) list abbreviations that are standard in specific fields. (On a related note: Such manuals also serve as resources on accepted nomenclature.) Use these and other standard abbreviations when strongly warranted. Largely avoid others. Those that you use should be introduced as carefully as you would introduce royalty.
Source: Gastel Barbara, Day Robert A. (2016), How to Write and Publish a Scientific Paper, Greenwood; 8th edition.