Contrasting patterns of evolutionary constraint and novelty revealed by comparative sperm proteomic analysis in Lepidoptera

Background: Rapid evolution is a hallmark of reproductive genetic systems and arises through the combined processes of sequence divergence, gene gain and loss, and changes in gene and protein expression. While studies aiming to disentangle the molecular ramifications of these processes are progressing, we still know little about the genetic basis of evolutionary transitions in reproductive systems. Here we conduct the first comparative analysis of sperm proteomes in Lepidoptera, a group that exhibits dichotomous spermatogenesis, in which males produce a functional fertilization-competent sperm (eupyrene) and an incompetent sperm morph lacking nuclear DNA (apyrene). Through the integrated application of evolutionary proteomics and genomics, we characterize the genomic patterns potentially associated with the origination and evolution of this unique spermatogenic process and assess the importance of genetic novelty in Lepidopteran sperm biology. Results: Comparison of the newly characterized Monarch butterfly (Danaus plexippus) sperm proteome to those of the Carolina sphinx moth (Manduca sexta) and the fruit fly (Drosophila melanogaster) demonstrated conservation at the level of protein abundance and post-translational modification within Lepidoptera. In contrast, comparative genomic analyses across insects reveals significant divergence at two levels that differentiate the genetic architecture of sperm in Lepidoptera from other insects. First, a significant reduction in orthology among Monarch sperm genes relative to the remainder of the genome in non-Lepidopteran insect species was observed. Second, a substantial number of sperm proteins were found to be specific to Lepidoptera, in that they lack detectable homology to the genomes of more distantly related insects. Lastly, the functional importance of Lepidoptera specific sperm proteins is broadly supported by their increased abundance relative to proteins conserved across insects. Conclusions: Our results identify a burst of genetic novelty amongst sperm proteins that may be associated with the origin of heteromorphic spermatogenesis in ancestral Lepidoptera and/or the subsequent evolution of this system. This pattern of genomic diversification is distinct from the remainder of the genome and thus suggests that this transition has had a marked impact on lepidopteran genome evolution. The identification of abundant sperm proteins unique to Lepidoptera, including proteins distinct between specific lineages, will accelerate future functional studies aiming to understand the developmental origin of dichotomous spermatogenesis and the functional diversification of the fertilization incompetent apyrene sperm morph

Point prevalence of penicillin allergy in hospital inpatients

Ten percent of the general population believe themselves to be allergic to beta-lactams, many erroneously. Alternative, broader-spectrum antibiotics are associated with increased drug costs and colonization with resistant organisms. A point prevalence study of hospital inpatients determined the local reported rate of penicillin allergy, the nature of allergy described, evidence of antimicrobial resistance and antimicrobial regimens used as a result. Of the 583 patients assessed, the overall rate of penicillin allergy was 13.7% [95% confidence interval (CI) 11-17%]. Rash was the most commonly reported reaction (27.5%, 95% CI 18-39%). Details of the nature of the penicillin allergy were poorly recorded on drug charts. Significantly higher rates of meticillin-resistant Staphylococcus aureus were seen in the allergic cohort (P=0.0065) compared with those without a label of penicillin allergy; this was also seen for vancomycin-resistant enterococci, but this did not reach significance. This study demonstrates an increase in detection of resistant organisms in penicillin-allergic patients which may result from use of broader-spectrum antibiotics in this group.Supports Open AccessPublished version, accepted version (12 month embargo