Unfolded, misfolded, and self-organized short alanine-rich peptides: implications for fundamental science, human disease, and biotechnology

Protein folding is the reversible transition by which an unordered polypeptide chain attains its functional 3-D native structure. A detailed understanding of the principles which govern the protein folding process, such as how sequence codes for structure, remains elusive. Achieving a complete picture of the folding process requires information regarding structural preferences in the unfolded state. Moreover, understanding the principles which govern protein aggregation is of significant biomedical and biotechnological importance. Herein, short alanine-based peptides are used as model systems for studying both the structural preferences in the unfolded state as well as protein aggregation in relation to human disease, and exploitation of the self-assembly process for various biotechnological applications.It is now a central dogma of protein science that the unfolded state is not conformationally random, as was originally believed, but that, instead, residual structure exists. Here, we elucidate the conformational propensities of alanine in the unfolded state using short alanine-rich peptides as model systems. The intrinsic conformational propensities of alanine, as well as nearest neighbor effects are illuminated using various vibrational spectroscopic methods, combined with NMR results.Protein and peptide aggregation is affiliated with various seemingly unrelated diseases, including several neurodegenerative diseases and the systemic amyloidoses. It is of current belief that aggregation is a general feature of the protein energy landscape, suggesting that the various unrelated human pathologies linked to protein aggregation are linked by common principles. Herein, fibril formation of a short alanine-based peptide with no known disease affiliation is probed by vibrational circular dichroism (VCD) spectroscopy. In particular, it is demonstrated that peptide fibrils give rise to VCD intensity enhancement, illustrating the use of the technique as a novel means to probe aggregation kinetics.In addition to the biomedical relevance, protein and peptide self-assembly can be exploited as a means of constructing biomaterials with inherent biofunctionality. In this regard, oligopeptide-based hydrogels have shown potential as drug delivery systems and tissue engineering scaffolds. Herein, the unique properties of a novel class of self-assembling alanine-rich oligoopeptides are presented. In particular, it is demonstrated that conformational instability can be exploited to tune the physicochemical properties of hydrogels formed by such systems, for the potential use in various biotechnological applications.Ph.D., Physical Chemistry -- Drexel University, 201

Using the IUCN Environmental Impact Classification for Alien Taxa to inform decision-making

The Environmental Impact Classification for Alien Taxa (EICAT) is an important tool for biological invasion policy and management and has been adopted as an International Union for Conservation of Nature (IUCN) standard to measure the severity of environmental impacts caused by organisms living outside their native ranges. EICAT has already been incorporated into some national and local decision-making procedures, making it a particularly relevant resource for addressing the impact of non-native species. Recently, some of the underlying conceptual principles of EICAT, particularly those related to the use of the precautionary approach, have been challenged. Although still relatively new, guidelines for the application and interpretation of EICAT will be periodically revisited by the IUCN community, based on scientific evidence, to improve the process. Some of the criticisms recently raised are based on subjectively selected assumptions that cannot be generalized and may harm global efforts to manage biological invasions. EICAT adopts a precautionary principle by considering a species’ impact history elsewhere because some taxa have traits that can make them inherently more harmful. Furthermore, non-native species are often important drivers of biodiversity loss even in the presence of other pressures. Ignoring the precautionary principle when tackling the impacts of non-native species has led to devastating consequences for human well-being, biodiversity, and ecosystems, as well as poor management outcomes, and thus to significant economic costs. EICAT is a relevant tool because it supports prioritization and management of non-native species and meeting and monitoring progress toward the Kunming–Montreal Global Biodiversity Framework (GBF) Target 6

Elevational Patterns of Species Richness, Range and Body Size for Spiny Frogs

Quantifying spatial patterns of species richness is a core problem in biodiversity theory. Spiny frogs of the subfamily Painae (Anura: Dicroglossidae) are widespread, but endemic to Asia. Using spiny frog distribution and body size data, and a digital elevation model data set we explored altitudinal patterns of spiny frog richness and quantified the effect of area on the richness pattern over a large altitudinal gradient from 0–5000 m a.s.l. We also tested two hypotheses: (i) the Rapoport's altitudinal effect is valid for the Painae, and (ii) Bergmann's clines are present in spiny frogs. The species richness of Painae across four different altitudinal band widths (100 m, 200 m, 300 m and 400 m) all showed hump-shaped patterns along altitudinal gradient. The altitudinal changes in species richness of the Paini and Quasipaini tribes further confirmed this finding, while the peak of Quasipaini species richness occurred at lower elevations than the maxima of Paini. The area did not explain a significant amount of variation in total, nor Paini species richness, but it did explain variation in Quasipaini. Five distinct groups across altitudinal gradient were found. Species altitudinal ranges did not expand with an increase in the midpoints of altitudinal ranges. A significant negative correlation between body size and elevation was exhibited. Our findings demonstrate that Rapoport's altitudinal rule is not a compulsory attribute of spiny frogs and also suggest that Bergmann's rule is not generally applicable to amphibians. The study highlights a need to explore the underlying mechanisms of species richness patterns, particularly for amphibians in macroecology

Confronting taxonomic vandalism in biology: conscientious community self-organization can preserve nomenclatural stability

© 2021 The Authors. Published by Oxford University Press. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1093/biolinnean/blab009Self-published taxon descriptions, bereft of a basis of evidence, are a long-standing problem in taxonomy. The problem derives in part from the Principle of Priority in the International Code of Zoological Nomenclature, which forces the use of the oldest available nomen irrespective of scientific merit. This provides a route to ‘immortality’ for unscrupulous individuals through the mass-naming of taxa without scientific basis, a phenomenon referred to as taxonomic vandalism. Following a flood of unscientific taxon namings, in 2013 a group of concerned herpetologists organized a widely supported, community-based campaign to treat these nomina as lying outside the permanent scientific record, and to ignore and overwrite them as appropriate. Here, we review the impact of these proposals over the past 8 years. We identified 59 instances of unscientific names being set aside and overwritten with science-based names (here termed aspidonyms), and 1087 uses of these aspidonyms, compared to one instance of preference for the overwritten names. This shows that when there is widespread consultation and agreement across affected research communities, setting aside certain provisions of the Code can constitute an effective last resort defence against taxonomic vandalism and enhance the universality and stability of the scientific nomenclature

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/ taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems

Light-Triggered Disassembly of Amyloid Fibrils

There is growing demand for novel methods that could render the controlled disassembly of higher-order structures formed, for example, by peptides. Herein, we demonstrate such a method based on the application of a photocaged variant of the amino acid lysine, namely, lys­(Nvoc). Specifically, we introduce lys­(Nvoc) into the primary sequence of the amyloidogenic peptide, Aβ_16–22, at a position where the native side chain is known to play a key role in fibril formation via hydrophobic interactions. Both AFM and infrared spectroscopic measurements indicate that the resultant Aβ_16–22 mutant is able to form fibrils whereas, more importantly, the fibrils thus formed can be completely disassembled upon irradiation with near-UV light, which cleaves the photolabile Nvoc moiety and triggers the restoration of the lysine side chain. These results suggest that the generation of a single charge in a highly hydrophobic region of the fibrils is sufficient to promote their dissociation. Thus, we envisage that the current approach will find useful applications wherein controlled structural disassembly or content release is required