Further delays were caused by duplication of stages, slide labelling, batching and inappropriate quality control.
The expressed multiple loci of MHC Class I/II is considered to be the crucial role acted by one or two rounds of whole-genome duplication (WGD) at stage of fish or amphibians.
However, this explanation is not mutually exclusive with a scenario of increasing gene dosage by gene duplication at later stages of development.
As soon as genome sequences of bacteria became available, it has been shown that a substantial fraction of the genome of each species, from approximately one third in bacteria with very small genomes, to a significant majority in species with larger genomes, consists of families of paralogs, genes that evolved via gene duplication at different stages of evolution [ 6- 9].
These models can be categorized by their assumptions: they can be either neutral or involving natural selection, and can consider the early stage of duplication, i.e. when the duplication is not yet fixed in the species or start with the assumption that the gene duplication has just been fixed (recently reviewed in [ 11]).
For example, the nucleus at Fig. 4n was unmistakably identified as a diploid at prophase because it had four FISH signals on four stringy chromatins, which means a pair of 45S rDNA in a diploid genome undergoing a duplication process at this stage.
Among the four genes found in section B2, two genes (OsYSL9 and OsYSL16) were localized to chromosome 4 and the other two (OsYSL2 and OsYSL15) were localized to chromosome 2. Figure 3 Chromosomal location, duplication event, and evolutionary stage schematic for OsOPT genes.
Orai molecules also underwent a round of gene duplication at the early stage of vertebrates [3].
Thus, the large number of OlfC genes in cichlids arose by gene duplication in the early stage of their evolution.
Monocotyledons are a branch of angiosperms whose genome has undergone a global duplication at an early stage of its evolution (Salse et al., 2009).
