I am reading through Recombinant DNA; Genes and Genomes - A Short Course - Third Edition by James D. Watson, et. al. and I came across this paragraph in the discussion about discrete factors of inheritance in Mendelian genetics:

The character shown by a plant depends on the pair of factors it receives from its parents. If both factors it receives are the same, that is, two dominant (yellow seed) or two recessive (green seed), then the plant exhibits those traits - yellow seeds for the former and green seeds for the latter. If one factor is dominant and the other recessive, then the dominant character is expressed; in this case, a plant with a factor for yellow seed and one for green seed will show the dominant trait, yellow seed. But the factor for green seed persists, even if the plant is yellow, and can reappear unchanged in later generations. This was a signal advance. In the 19th century it was believed that the traits of parents were blended in their offspring and, once mixed, the contributing traits could not be recovered. At the time, this was a severe problem for Charles Darwin's theory of evolution through natural selection. His critics pointed to that any favorable variation arising in an individual would have no long-term effect, because it would immediately be lost by blending.

Note: Added emphasis is mine.

I have done both Google and Google Scholar searches for

  • Signal Advance
  • Signal Advance Biology
  • Signal Advance Genetics
  • Signal Advance Science

and I have not had much success finding a definition for the use in this context.

One article, Plant biology: Signal advance for abscisic acid was one of the only relevant references I could find that used the words in combination, however they were only used in the title.

I am not sure of the context that it is being used in Recombinant DNA or in the plant biology article.

Are they saying that the signal advance marked a change in thinking on the subject, the way we would use the terms paradigm shift or quantum leap?

Or are they instead using the term in the sense of the recessive gene being maintained in the genome and was able to be expressed in future generations?

I have not come across the use of the term signal advance before, and it is difficult to work out from the context as the first half of the paragraph speaks about the genetics and then the second paragraph discusses how it provided evidence to change the hypothesis of the day.

There is a similar problem with the plant biology news and views as it talks about six new papers on a topic that had been elusive, but as it happens to be about a signaling pathway; I am left wondering the context here as well.

If anyone has come across this before and can help to clarify it for me, I would appreciate it. Thank you.

  • $\begingroup$ I almost wonder if this isn't a typo for 'singular'. I have no idea but I am curious. $\endgroup$ – Resonating Dec 14 '15 at 15:55
  • $\begingroup$ @Resonating I do not think that they meant singular. Your question made me think about the grammatical structure of the Watson sentence, and it seems to be Signal as adjective and Advance as noun. When I looked at the definition of Signal as an adjective, there is this unusual; notable; outstanding: I think that both authors may be using it in this regard, but I still want to see if there might me a biological perspective to it. $\endgroup$ – AMR Dec 14 '15 at 17:59
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    $\begingroup$ @AMR you are essentially correct in your interpretation. "Signal" is a Britishism meaning key or important or groundbreaking. I think it's a bit old-fashioned, as I haven't really seen it much in contemporary literature, but I may be wrong on that part (I'm 'Murican, after all...). $\endgroup$ – MattDMo Dec 15 '15 at 0:58
  • $\begingroup$ @MattDMo Hmm... That would make sense, something that Watson picked up at Cambridge.... Also one of the co-authors, Jan A. Witkowski may be British as he was educated in England. $\endgroup$ – AMR Dec 15 '15 at 3:28
  • $\begingroup$ I found it in another context and would agree. I don't see anything in the paragraph that would mean it had anything to do with the more common meaning of signalling. $\endgroup$ – Nathan Dec 15 '15 at 18:18

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