21.   But biologists have now discovered to their amazement that almost the entire courtship repertoire of the male fruitfly is governed by a single gene.

22.   But biologists have now discovered to their amazement that almost the entire courtship repertoire of the male fruit fly is governed by a single gene.

23.   But fatal diseases caused by a single gene are extremely rare.

24.   But Blum warns against simplistic conclusions about single genes and single disorders.

25.   But even the single gene defects more common in sperm can have large consequences.

26.   But the new experiments, by using a single gene to accomplish the same outcome, are far more sophisticated and revealing of the genetics of eye development.

27.   By contrast, diseases caused by a single defective gene could, at least in theory, be cured by gene therapy.

28.   By slightly disabling a single gene, researchers report that they have doubled the life span of fruit flies.

29.   Crosses between the terrestrial and aquatic forms had suggested that a single gene made the difference.

30.   Diversa and Applied Molecular Evolution tend to use mutations in a single gene.