The importance of mass spectrometric dereplication in fungal secondary metabolite analysis

Having entered the Genomic Era, it is now evident that the biosynthetic potential of filamentous fungi is much larger than was thought even a decade ago. Fungi harbor many cryptic gene clusters encoding for the biosynthesis of polyketides, non-ribosomal peptides, and terpenoids – which can all undergo extensive modifications by tailoring enzymes – thus potentially providing a large array of products from a single pathway. Elucidating the full chemical profile of a fungal species is a challenging exercise, even with elemental composition provided by high-resolution mass spectrometry (HRMS) used in combination with chemical databases (e.g. Antibase) to dereplicate known compounds. This has led to a continuous effort to improve chromatographic separation in conjunction with improvement in HRMS detection. Major improvements have also occurred with 2D chromatography, ion-mobility, MS/MS and MS3, stable isotope labeling feeding experiments, classic UV/Vis, and especially automated data-mining and metabolomics software approaches as the sheer amount of data generated is now the major challenge. This review will focus on the development and implementation of dereplication strategies and will highlight the importance of each stage of the process from sample preparation to chromatographic separation and finally towards both manual and more targeted methods for automated dereplication of fungal natural products using state-of-the art MS instrumentation

A new view of responses to first-time barefoot running.

We examined acute alterations in gait and oxygen cost from shod-to-barefoot running in habitually-shod well-trained runners with no prior experience of running barefoot. Thirteen runners completed six-minute treadmill runs shod and barefoot on separate days at a mean speed of 12.5 km·h-1. Steady-state oxygen cost in the final minute was recorded. Kinematic data were captured from 30-consecutive strides. Mean differences between conditions were estimated with 90% confidence intervals. When barefoot, stride length and ground-contact time decreased while stride rate increased. Leg-and vertical stiffness and ankle-mid-stance dorsi-flexion angle increased when barefoot while horizontal distance between point of contact and the hip decreased. Mean oxygen cost decreased in barefoot compared to shod running (90% CI -11% to -3%) and was related to change in ankle angle and point-of-contact distance, though individual variability was high (-19% to +8%). The results suggest that removal of shoes produces an alteration in running gait and a potentially-practically-beneficial reduction in mean oxygen cost of running in trained-habitually-shod runners new to running barefoot. However, high variability suggests an element of skill in adapting to the novel task and that caution be exercised in assuming the mean response applies to all runners