I'll start with the humble comma. Comparable to the lowly pawn in chess – a piece that is relatively weak in itself, but that can be crucial in separating weighty entities – the comma can decide the whole meaning of part or whole of a sentence. We barely appreciate this little mark, but we certainly notice its absence. Here's one of my favourite examples: ‘To advance the field studies in the area of behavioural ecology need to be conducted on several populations under similar climatic conditions’. A rather fiendish example, I grant you, but not an uncommon type, in my experience. As I progress through this sentence for the first time, I would instinctively feel that a term had been accidentally left out at the point of ‘ecology need’. However, on reaching the end, I quickly realize that there's another meaning, and that rather than a term, it's a comma that's missing, namely between ‘field’ and ‘studies’. OK, you might think, no big deal. However, it has created a hiatus in your reading flow, and distracted your attention from one concept towards a phantom alternative: quite annoying, really. In general, it is a good idea to place a comma behind the introductory concept in such sentences. As an editor I can confidently state that it is missing commas that most disturb my flow of reading. A riot of unnecessary commas is almost as bad, but I overwhelmingly experience the opposite. More commas, please! Often, the need for a comma only becomes evident in a rather particular context, e.g. ‘…many regulatory mechanisms may be the cause. However the causative regulatory effect is mediated…’, which was intended as ‘However, the causative regulatory effect is mediated…’. Hence, it is good to get into the habit of separating the initial part of a sentence with a comma in preparation for the eventuality of ambiguity. Along similar lines, another useful place for the comma is in separating concepts – rather than individual words – with ‘and’, as per the following example: ‘This transcriptional activation can be demonstrated and utilized in a variety of genetic backgrounds’. Does this mean that the transcriptional activation can both be demonstrated in a variety of genetic backgrounds, and also utilized [as a tool] in a variety of genetic backgrounds? Or does it mean that it can be demonstrated in a particular system, and then utilized in a variety of other settings? Placing a comma before ‘and’ confirms the latter, if indeed intended. Often a meaning is disambiguated in a subsequent phrase or sentence, but how much better to present it unambiguously immediately. Note, it's not necessary to place a comma before ‘and’ in the following: ‘nematodes, fruitflies, zebrafish, rodents and humans’: simple nouns do not need to be separated in that way. Another useful punctuation mark is the colon ‘:’, which, in prose, is properly used to state the second half of a logical pair, e.g. ‘An important question is: How pervasive is the She1 mechanism?’ or to signify ‘that is to say’ or ‘a logical consequence of this is’, e.g. ‘One key difference between these mechanisms is the degree to which a change is heritable: given the state of a molecular system in an individual … will the next generation inherit that state or not?’. I wouldn't mind seeing more colons used in this way: they can very conveniently divide a very long sentence, simultaneously saving words by codifying the conceptual connexion between two phrases. They can also precede an explanation. Not to be confused with the colon is the semi-colon ‘;’, which is properly used to qualify or contextualize a preceding concept – e.g. ‘astral microtubules slide along the cell cortex in front of the advancing spindle; reminiscent of how cortical dynein pulls astral microtubules’ – to negate a preceding concept, or to introduce another component in a list. Semi-colons can also be used to break long sentences. And so, finally, to parentheses ‘()’, a device that should really be used with care: avoid at all costs placing important concepts between them. They tend to direct the reader's eye ‘up and over’ in an attempt to preserve the flow of the main sentence. Such intervening qualifications or precisions should be kept relatively short, and inserted between so-called ‘en’ dashes. Andrew Moore Editor-in-Chief
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