Worms take to the slo lane: a perspective on the mode of action of emodepside

The cyclo-octapdepsipeptide anthelmintic emodepside exerts a profound paralysis on parasitic and free-living nematodes. The neuromuscular junction is a significant determinant of this effect. Pharmacological and electrophysiological analyses in the parasitic nematode Ascaris suum have resolved that emodepside elicits a hyperpolarisation of body wall muscle, which is dependent on extracellular calcium and the efflux of potassium ions. The molecular basis for emodepside’s action has been investigated in forward genetic screens in the free-living nematode Caenorhabditis elegans. Two screens for emodepside resistance, totalling 20,000 genomes, identified several mutants of slo-1, which encodes a calcium-activated potassium channel homologous to mammalian BK channels. Slo-1 null mutants are more than 1000-fold less sensitive to emodepside than wild-type C. elegans and tissue-specific expression studies show emodepside acts on SLO-1 in neurons regulating feeding and motility as well as acting on SLO-1 in body wall muscle. These genetic data, combined with physiological measurements in C. elegans and the earlier physiological analyses on A. suum, define a pivotal role for SLO-1 in the mode of action of emodepside. Additional signalling pathways have emerged as determinants of emodepside’s mode of action through biochemical and hypothesis-driven approaches. Mutant analyses of these pathways suggest a modulatory role for each of them in emodepside’s mode of action; however, they impart much more modest changes in the sensitivity to emodepside than mutations in slo-1. Taken together these studies identify SLO-1 as the major determinant of emodepside’s anthelmintic activity. Structural information on the BK channels has advanced significantly in the last 2 years. Therefore, we rationalise this possibility by suggesting a model that speculates on the nature of the emodepside pharmacophore within the calcium-activated potassium channels

Report on the 13th symposium on invertebrate neurobiology held 26–30 August 2015 at the Balaton Limnological Institute, MTA Centre for ecological research of the Hungarian Academy of Sciences, Tihany, Hungary

This report summarizes the lectures and posters presented at the International Society for Invertebrate Neurobiology’s 13th symposium held 26–30 August 2015, at the Balaton Limnological Institute, MTA Centre for Ecological Research, Tihany, Hungary. The symposium provided an opportunity for scientists working on a range of topics in invertebrate neurobiology to meet and present their research and discuss ways to advance the disciplin

Conformational evolution of molecular signatures during Amyloi-dogenic protein aggregation

Aggregation is a pathological hallmark of proteinopathies such as Alzheimer’s disease and results in the deposition of β-sheet-rich amyloidogenic protein aggregates. Such proteinopathies can be classified by the identity of one or more aggregated protein, with recent evidence also suggesting that distinct molecular conformers (strains) of the same protein can be observed in different diseases, as well is in sub-types of the same disease. Therefore, methods for the quantification of pathological changes in protein conformation are central to understanding and treating proteinopathies. In this work the evolution of Raman spectroscopic molecular signatures of three conformationally distinct proteins, Bovine Serum Albumin (α-helical-rich), β2-microglobulin (β-sheet-rich) and tau (natively disordered), was assessed during aggregation into oligomers and fibrils. The morphological evolution was tracked using Atomic Force Microscopy and corresponding conformational changes were assessed by their Raman signatures acquired in both wet and dried conditions. A deconvolution model was developed which allowed us to quantify the conformation of the non-regular protein tau, as well as for the oligomeric and fibrillar species of each of the proteins. Principle component analysis of the fingerprint region allowed further identification of the distinguishing spectral features and unsupervised distinction. While an increase in β-sheet is seen on aggregation, crucially, however, each protein also retains a significant proportion of its native monomeric structure after aggregation. Thus, spectral analysis of each aggregated species, oligomeric, as well as fibrillar, for each protein resulted in a unique and quantitative ‘conformational fingerprint’. This approach allowed us to provide the first differential detection of both oligomers and fibrils of the three different amyloidogenic proteins, including tau, whose aggregates have never before been interrogated using spontaneous Raman spectroscopy. Quantitative ‘conformational fingerprinting’ by Raman spectroscopy thus demonstrates its huge potential and utility in understanding proteinopathic disease mechanisms and for providing strain-specific early diagnostic markers and targets for disease-modifying therapies

Characterising nicotinic acetylcholine receptors in the plant parasitic nematode Globodera pallida

G. pallida is a cyst nematode; infective juvenile worms locate and invade host potato roots within a short time period while the environmental conditions are optimal. Therefore, locomotion is an essential component of its invasion strategy. It belongs to the phylum Nematoda, which also includes the free-living model genetic nematode C. elegans. We explored the idea that the neurobiological basis of C. elegans locomotion is likely to be conserved between nematodes and provide a route to new molecular targets for pest control

Conformational fingerprinting of tau variants and strains by Raman spectroscopy

Tauopathies are a group of disorders in which the deposition of abnormally folded tau protein accompanies neurodegeneration. The development of methods for detection and classification of pathological changes in protein conformation are desirable for understanding the factors that influence the structural polymorphism of aggregates in tauopathies. We have previously demonstrated the utility of Raman spectroscopy for the characterization and discrimination of different protein aggregates, including tau, based on their unique conformational signatures. Building on this, in the present study, we assess the utility of Raman spectroscopy for characterizing and distinguishing different conformers of the same protein which in the case of tau are unique tau strains generated in vitro. We now investigate the impact of aggregation environment, cofactors, post-translational modification and primary sequence on the Raman fingerprint of tau fibrils. Using quantitative conformational fingerprinting and multivariate statistical analysis, we found that the aggregation of tau in different buffer conditions resulted in the formation of distinct fibril strains. Unique spectral markers were identified for tau fibrils generated using heparin or RNA cofactors, as well as for phosphorylated tau. We also determined that the primary sequence of the tau monomer influenced the conformational signature of the resulting tau fibril, including 2N4R, 0N3R, K18 and P301S tau variants. These results highlight the conformational polymorphism of tau fibrils, which is reflected in the wide range of associated neurological disorders. Furthermore, the analyses presented in this study provide a benchmark for the Raman spectroscopic characterization of tau strains, which may shed light on how the aggregation environment, cofactors and post-translational modifications influence tau conformation in vivo in future studies

Dataset supporting the publication "All-fiberized 1840-nm femtosecond thulium fiber laser for label-free multiphoton microscopy".

This dataset supports the publication by Duanyang Xu et al (2023) &quot;All-fiberized 1840-nm femtosecond thulium fiber laser for label-free multiphoton microscopy&quot; published in Biomedical Optics Express. This dataset contains experimental data for the paper specifically on that from the 6 figures from the article.</span

A versatile, low cost light source module for multiphoton imaging

Multiphoton imaging methods such as Coherent Raman Scattering (CRS) microscopy which also comprises Second Harmonic Generation (SHG) and Two Photon Excited Auto-Fluorescence (TPEAF) imaging (termed as multimodal Coherent Raman microscopy), have greatly facilitated the advancement of biomedical research due to their unique features. Multimodal CRS microscopy, is label free, chemically specific, inherently 'confocal' offering three independent contrast mechanisms which can be associated in a composite image comprising a wide range of chemical and structural information about the interrogated sample. The standard light source for multimodal CRS microscopy is a picosecond pumped Optical Parametric Oscillator (OPO) which has exhibited excellent performance but due to its associated high cost, maintenance, complexity and requirement of a dedicated optics laboratory, has hindered the wider adoption of multimodal CRS microscopy and especially its deployment in clinical applications. Here we present a novel, low cost Optical Parametric Amplifier (OPA) based on a MgO doped Periodically Poled Lithium Niobate (PPLN) crystal seeded by a continuous wave (CW) laser source and pumped by a picosecond laser at 1031nm, which removes any synchronisation requirements. We show that this OPA is a versatile light source module that can be tailored to the tunability and affordability requirements of the specific application. We demonstrate that it can be used either in association with an OPO or on its own as a light source for multimodal CRS microscopy and we show its performance by imaging a variety of standards and biological samples.</p

All-fiberized 1840-nm femtosecond thulium fiber laser for label-free nonlinear microscopy

We report an all-fiberized 1840-nm thulium-fiber-laser source, comprising a dissipative-soliton mode-locked seed laser and a chirped-pulse-amplification system for label-free biological imaging through nonlinear microscopy. The mode-locked thulium fiber laser generated dissipative-soliton pulses with a pre-chirped duration of 7 ps and pulse energy of 1 nJ. A chirped-pulse fiber-amplification system employing an in-house-fabricated, short-length, single-mode, high-absorption, thulium fiber delivered pulses with energies up to 105 nJ. The pulses were capable of being compressed to 416 fs by passing through a grating pair. Imaging of mouse tissue and human bone samples was demonstrated using this source via third-harmonic generation microscopy