piRNA-guided slicing of transposon transcripts enforces their transcriptional silencing via specifying the nuclear piRNA repertoire.

PIWI clade Argonaute proteins silence transposon expression in animal gonads. Their target specificity is defined by bound ∼23- to 30-nucleotide (nt) PIWI-interacting RNAs (piRNAs) that are processed from single-stranded precursor transcripts via two distinct pathways. Primary piRNAs are defined by the endonuclease Zucchini, while biogenesis of secondary piRNAs depends on piRNA-guided transcript cleavage and results in piRNA amplification.

Predictors of vaccination rates during a mass meningococcal vaccination program on a college campus.

Factors contributing to students' compliance with mass vaccination programs during meningococcal outbreaks have not been well described. A 1997 mass vaccination campaign at Michigan State University provided an opportunity to study such factors. Of 34,024 students in the target population, 17,538 (51.