Extensive differences in individual animal responses to IFN-т treatment occurred in the present study, irrespective of the dose of ovIFN-т administered (Fig. 2). Others have also observed such disparate responses to ovIFN-т treatment. It is not clear why such variable responses occur, but it may well be that failure of individual animals to respond robustly to these antiluteo-lytic factors is a primary cause of early pregnancy failure. buy ampicillin
It is also unclear how the progenitor gene of the present day IFNTs and their relatives, the IFNWs, gained six extra amino acids. There are several examples in which base insertions and/or deletions at or near the translation stop codon permits incorporation of part of the 3′ untranslated region into the coding sequence. The p-subunit of hCG, for example, is 24 amino acids longer at its carboxyl terminus than its homolog, huLH-|3, because of a single base deletion at the normal stop codon of the gene for huLH-p and a two-base insertion at a more distal site. Together, these mutations extended the reading frame into the 3′ untranslated region of the LH-|J gene. The carboxyl tail of hCG-(3 is unimportant for either receptor binding or biological activity. By contrast, there are no obvious base insertions or deletions that can account for extension in reading frame for IFNT and IFNW. It may be that the mutational events can no longer be traced because too much time has elapsed since divergence of the IFNT/W progenitor gene from the IFNA lineage. An alternative explanation is that a recombination event occurred near the end of the open reading frame of IFNA to provide a novel 3′ end to the new IFNT/W progenitor gene.