Navy blue. For other uses, see Navy blue (disambiguation). Navy blue is a very dark shade of the color blue. French sailor in dark blue uniform. Navy blue got its name from the dark blue (contrasted with white) worn by officers in the British Royal Navy since 1748 and subsequently adopted by other navies around the world.
Hybrid sterility is what results when individuals from two. different species are able to mate but their offspring is infertile, meaning that their. offspring are not able to reproduce. Because this occurs after the formation of the. zygote, this is a postzygotic isolating mechanism, not a prezygotic mechanism.
For intra-chromosomal recombination, the intervening DNA must be flanked by a pair of recombination sites, a process difficult to achieve through the random placement of transgenes. Unlike fungal and animal systems, the insertion of transgenes through homologous recombination in plants is not yet practical. To examine intra-chromosomal recombination, the dissociation element (Ds) and the activator element (Ac), transposons, a specific system was developed.