One thousand DNA barcodes of piranhas and pacus reveal geographic structure and unrecognised diversity in the Amazon

Piranhas and pacus (Characiformes: Serrasalmidae) are a charismatic but understudied family of Neotropical fishes. Here, we analyse a DNA barcode dataset comprising 1,122 specimens, 69 species, 16 genera, 208 localities, and 34 major river drainages in order to make an inventory of diversity and to highlight taxa and biogeographic areas worthy of further sampling effort and conservation protection. Using four methods of species discovery - incorporating both tree and distance based techniques - we report between 76 and 99 species-like clusters, i.e. between 20% and 33% of a priori identified taxonomic species were represented by more than one mtDNA lineage. There was a high degree of congruence between clusters, with 60% supported by three or four methods. Pacus of the genus Myloplus exhibited the most intraspecific variation, with six of the 13 species sampled found to have multiple lineages. Conversely, piranhas of the Serrasalmus rhombeus group proved difficult to delimit with these methods due to genetic similarity and polyphyly. Overall, our results recognise substantially underestimated diversity in the serrasalmids, and emphasise the Guiana and Brazilian Shield rivers as biogeographically important areas with multiple cases of across-shield and within-shield diversifications. We additionally highlight the distinctiveness and complex phylogeographic history of rheophilic taxa in particular, and suggest multiple colonisations of these habitats by different serrasalmid lineages. © 2018 The Author(s)

Cellular- and Acellular-Based Therapies: Skin Substitutes and Matrices

Recalcitrant wounds pose a challenge to the dermatologist. In recent years, many skin substitutes have been developed and are broadly classified as either acellular or cellular. These skin substitutes are to be used in concert with standard of care to provide the stalled wound with a scaffold and key elements such as cytokines, growth factors, and extracellular matrix substances. Skin substitutes help initiate and accelerate wound healing through granulation, cell migration, re-vascularization, and re-epithelialization. Wounds of varying etiologies have been shown to benefit from the multitude of acellular and cellular skin substitutes that are available. This chapter provides clinically relevant background and practical guidance about skin substitutes to allow dermatologists to effectively incorporate these powerful tools into their wound healing armamentarium