This finding suggested that breed made a difference and that genetics were a major factor in the susceptibility of sheep to OPPV, Heaton says.
The researchers genotyped animals using blood samples collected over the years and discovered a gene, TMEM154, that influences OPPV infection.
Haplotypes 2 and 3 were strongly associated with OPPV infection and considered to be highly susceptible forms of TMEM154.
Although these results are promising, OPPV is highly adaptable and affects flocks differently, Heaton adds.
Diagnostic tests have been available for some time to determine whether sheep are infected with OPPV, Leymaster says.
The calculations showed that in both OPv and OPPv the two iron ions prefer to stay closer, in line with the results of dilute Mn in ZnO crystal (Sharma et al., 2003).
The total DOS for the OPPv at 0 GPa is included for comparison.
It is also noted that our calculations showed a low transition pressure (about 24 GPa) from the (Mg,Fe)(Si,Fe)[O.sub.3] OPv to the OPPv form, which is much higher than the transition range (>90 GPa) for x=12.5% (Mg1-xFex)Si[O.sub.3] (Mao et al., 2005).
The calculations showed that the transition pressure from the OPv to the OPPv phase decreases as the Fe concentration increases.
Such mixed [Fe.sup.2+] ions and [Fe.sup.2+]-[Fe.sup.4+] clusters would cause distortion of the Si-O network in the OPVs and OPPvs, as well as the local symmetry and structure of the Fe ions.
"With one or both of these tests, we hope to provide a diagnostic method that determines or predicts whether the sheep will progress to OPPV
clinical signs," says Herrmann-Hoesing.