is a "pioneer round" of translation stil the model for how the transription apparatus recognizes premature stop codons? for some reason I had thought that model had been replaced.

well i haven't made much of an effort to understand premature termination codon detection. but what little i've read about nonsense-mediated decay has pointed me in that direction.

according to this review
(doi:10.1146/annurev.biochem.76.050106.093909)
it looks like mammals do the pioneer thing but cervisiae doesn't.

It remains to be determined whether yeast and mammals truly differ with regard to what rounds of translation triggers NMD. It is possible, for example, that yeast NMD is more often triggered during early rather than later rounds of translation. Conversely, mammalian NMD may occur to some extent in later rounds. Consistent with this, the substrate for mammalian NMD does not absolutely require using a CBC-dependent mechanism because mRNAs containing internal ribosome entry sites can be degraded by NMD (129, 130).