Analysis of mature miRNA sequences cloned from mouse T cells suggests that compared to the other abundantly expressed miRNAs, miR-142 is unique in that it exhibits a high frequency of variation at the 5' end.
The increasing number of reports addressing the high frequency of variation in the 3'UTR [ 28, 29] and its consequences on gene regulation [ 30] makes it necessary to study target prediction in more detail.
Intergenic transcripts had a higher frequency of variation compared with non-intergenic transcripts.
Previous studies revealed a high frequency of genetic variations in SPANX-A/D genes.
We asked whether OR genes harbor an unusually high frequency of missense variations.
The presence of simple sequence repeats coding for amino acid repeats ranging from 8 to 26 residues may explain the high frequency of length variations.
Also some of miRNAs in C. elegans, such as miR-49, miR-228, miR-229*, miR-238, miR-240, miR-246, and miR-788 have high frequency of 5' end variation [40].
The 36 SNP markers used for diversity analysis produced 140 alleles, an average of 3.89 alleles per marker, suggesting a high frequency of allelic variation.
Therefore, it could be concluded that the high frequency of genetic variation majorly comes from the genomic shock during asymmetric somatic hybridization.
This study demonstrates that asymmetric somatic hybridization induces high frequency of genetic variation in a manner partially different from allopolipoidization. Asymmetric somatic hybridization provides appropriate material to comprehensively explore the nature of the genetic variation induced by genomic shock.
Another study in rice [ 12] also identified a high frequency of presence/absence variation in a subset of NBS-encoding genes between 21 cultivated and 14 wild rice populations, and postulated that such variation could potentially result from geographic differentiation.
