Differential elevational cline in the phenology and demography of two temporally isolated populations of a damselfly: Not two but one taxon?

1. Temporal isolation by cohort splitting is a life‐history mechanism that has been reported in many temperate insects, including those inhabiting freshwater habitats. Although the cohorts seem to maintain separate temporal niches in a specific location, the temporal isolation may be disrupted across a geographic gradient due to constraints imposed by seasonality. 2. This prediction was tested on two temporally isolated populations of the obligatory univoltine Lestes virens (Odonata, Lestidae) in north‐east Algeria. Although the two cohorts emerge at the same time in spring, one cohort reproduces in summer, while the second cohort estivates in summer and reproduces in autumn. A survey assessing the phenology and abundance was conducted on eight ponds across an elevational gradient (5–1012 m asl) using capture–mark–recapture and adult density sampling. 3. In all sites from low to high elevation, the species showed cohort splitting. The phenology of reproduction of both cohorts showed a delay with elevation, but the cline was 2.2 days for the summer cohort and 0.7 days for the autumn cohort per 100 m of elevation. Moreover, the density of adults in the autumn cohort was higher than that of summer cohort across the entire elevational range, and the difference increased with elevation. 4. These findings regarding the differential elevational cline in the phenology show that the temporal isolation of the two cohorts becomes narrower at high elevation, suggesting potential inter‐cohort temporal overlap at higher elevations. 5. The claim that the two cohorts of L. virens are true temporally isolated species needs further investigation.     

Single amino acid substitution in the PC1/3 propeptide can induce significant modifications of its inhibitory profile toward its cognate enzyme

The proprotein convertase PC1/3 is synthesized as a large precursor that undergoes proteolytic processing of the signal peptide, the propeptide and ultimately the COOH-terminal tail, to generate the mature form. The propeptide is essential for protease folding, and, although cleaved by an autocatalytic process, it remains associated with the mature form acting as an auto-inhibitor of PC1/3. To further assess the role of certain residues in its interaction with its cognate enzyme, we performed an alanine scan on two PC1/3 propeptide potential cleavable sites ((50)RRSRR(54) and (61)KR(62)) and an acidic region (65)DDD(67) conserved among species. Upon incubation with PC1/3, the ensuing peptides exhibit equal inhibitory potency, lower potency, or higher potency than the wild-type propeptide. The K(i) values calculated varied between 0.15 and 16.5 nm. All but one mutant exhibited a tight binding behavior. To examine the specificity of mutants, we studied their reactivity toward furin, a closely related convertase. The mutation of certain residues also affects the inhibition behavior toward furin yielding propeptides exhibiting K(i) ranging from 0.2 to 24 nm. Mutant propeptides exhibited against each enzyme either different mode of inhibition, enhanced selectivity in the order of 40-fold for one enzyme, or high potency with no discrimination. Hence, we demonstrate through single amino acid substitution that it is feasible to modify the inhibitory behavior of propeptides toward convertases in such a way as to increase or decrease their potency, modify their inhibitory mechanisms, as well as increase their selectivity.     

Snake (Walterinnesia aegyptia) venom-loaded silica nanoparticles induce apoptosis and growth arrest in human prostate cancer cells

Prostate cancer (PCa) is the most commonly diagnosed cancer in men. The progression and invasion of PCa are normally mediated by the overexpression of chemokine receptors (CKRs) and the interaction between CKRs and their cognate ligands. We recently demonstrated that venom extracted from Walterinnesia aegyptia (WEV) either alone or in combination with silica nanoparticles (WEV+NP) mediated the growth arrest and apoptosis of breast cancer cells. In the present study, we evaluated the impact of WEV alone and WEV+NP on the migration, invasion, proliferation and apoptosis of prostate cancer cells. We found that WEV alone and WEV+NP decreased the viability of all cell types tested (PCa cells isolated from patient samples, PC3 cells and LNCaP cells) using an MTT assay. The IC₅₀ values were determined to be 10 and 5 μg/mL for WEV alone and WEV+NP, respectively. WEV+NP decreased the surface expression of the CKRs CXCR3, CXCR4, CXCR5 and CXCR6 to a greater extent than WEV alone and subsequently reduced migration and the invasion response of the cells to the cognate ligands of the CKRs (CXCL10, CXCL12, CXCL13 and CXCL16, respectively). Using a CFSE proliferation assay, we found that WEV+NP strongly inhibited epidermal growth factor-mediated PCa cell proliferation. Furthermore, analysis of the cell cycle indicated that WEV+NP strongly altered the cell cycle of PCa cells and enhanced the induction of apoptosis. Finally, we demonstrated that WEV+NP robustly decreased the expression of anti-apoptotic effectors, such as B cell Lymphoma-2 (Bcl-2), B cell Lymphoma-extra large (Bcl-_XL) and myeloid cell leukemia sequence-1 (Mcl-1), and increased the expression of pro-apoptotic effectors, such as Bcl-2 homologous antagonist/killer (Bak), Bcl-2-associated X protein (Bax) and Bcl-2-interacting mediator of cell death (Bim). WEV+NP also altered the membrane potential of mitochondria in the PCa cells. Our data reveal the potential of nanoparticle-sustained delivery of snake venom as effective treatments for prostate cancer.     

Search of Extremely Sensitive Near-Infrared Plasmonic Interfaces: A Theoretical Study

The sensitivity of the wavelength position of localized surface plasmon resonance (LSPR) in metal nanostructures to local changes in the refractive index has been widely used for label-free detection strategies. Tuning the optical properties of the nanostructures from the visible to the infrared region is expected to have a drastic effect on the refractive index sensitivity. Here, we theoretically investigate the optical response of a newly designed plasmonic interface to changes in the bulk refractive index by the finite difference time domain method. It consists of a structured interface, where the planar interface is superposed with dielectric pillars 30 nm in height and 125 nm in length with a separation distance of 15 nm. The pillars are covered with U-shaped gold nanostructures of 50 nm in height, 125 nm in length, and 5 nm of gold base thickness. The whole structure is finally covered with a 5-nm thick dielectric layer of n ₂?=?2.63. This plasmonic structure shows bulk refractive index sensitivities up to 1750 nm/RIU (RIU : refractive index unit) in the near infrared (λ?=?2621 nm). The enhanced sensitivity is a consequence of the extremely enhanced electrical field between the gold nanopillars of the plasmonic interface.     

Cutting-edge multi-level analytical and structural characterization of antibody-drug conjugates: present and future

Introduction: The development and optimization of antibody drug conjugates (ADCs) rely on improving their analytical and bioanalytical characterization, by assessing critical quality attributes (CQAs). Among the CQAs, the glycoprofile, drug load distribution (DLD), the amount of unconjugated antibody (D0), the average drug-to-antibody ratio (DAR), the drug conjugation sites and the residual drug-linker and related product proportions (SMDs) in addition to high and low molecular weight species (H/LMWS), and charge variants are the most important ones.

Areas covered: The analytical and structural toolbox for the characterization of 1^st, 2^d and 3^d generation ADCs was significantly extended in the last 3 years. Here, we reviewed state-of-the-art techniques, such as liquid chromatography, high resolution native and ion mobility mass spectrometry, multidimensional liquid chromatography and capillary electrophoresis hyphenated to mass spectrometry, reported mainly since 2016.

Expert commentary: These emerging techniques allow a deep insight into important CQAs that are related to ADC Chemistry Manufacturing and Control (CMC) as well as an improved understanding of in vitro and in vivo ADC biotransformations. This knowledge and the development of quantitative bioanalytical assays will continue to contribute to early-developability assessment for the optimization of all the ADC components (i.e. antibody, drug, and linker) and help to bring next-generation ADCs into late clinical development and to the market.     

TMEM120A and B: Nuclear Envelope Transmembrane Proteins Important for Adipocyte Differentiation

Recent work indicates that the nuclear envelope is a major signaling node for the cell that can influence tissue differentiation processes. Here we present two nuclear envelope trans-membrane proteins TMEM120A and TMEM120B that are paralogs encoded by the Tmem120A and Tmem120B genes. The TMEM120 proteins are expressed preferentially in fat and both are induced during 3T3-L1 adipocyte differentiation. Knockdown of one or the other protein altered expression of several genes required for adipocyte differentiation, Gata3, Fasn, Glut4, while knockdown of both together additionally affected Pparg and Adipoq. The double knockdown also increased the strength of effects, reducing for example Glut4 levels by 95% compared to control 3T3-L1 cells upon pharmacologically induced differentiation. Accordingly, TMEM120A and B knockdown individually and together impacted on adipocyte differentiation/metabolism as measured by lipid accumulation through binding of Oil Red O and coherent anti-Stokes Raman scattering microscopy (CARS). The nuclear envelope is linked to several lipodystrophies through mutations in lamin A; however, lamin A is widely expressed. Thus it is possible that the TMEM120A and B fat-specific nuclear envelope transmembrane proteins may play a contributory role in the tissue-specific pathology of this disorder or in the wider problem of obesity.     

Analysis of myotilin turnover provides mechanistic insight into the role of myotilinopathy-causing mutations

In eukaryotes, disulfide bonds are formed in the endoplasmic reticulum, facilitated by the Ero1 (endoplasmic reticulum oxidoreductin 1) oxidase/PDI (protein disulfide-isomerase) system. Mammals have two ERO1 genes, encoding Ero1α and Ero1β proteins. Ero1β is constitutively expressed in professional secretory tissues and induced during the unfolded protein response. In the present work, we show that recombinant human Ero1β is twice as active as Ero1α in enzymatic assays. Ero1β oxidizes PDI more efficiently than other PDI family members and drives oxidative protein folding preferentially via the active site in the á domain of PDI. Our results reveal that Ero1β oxidase activity is regulated by long-range disulfide bonds and that Cys130 plays a critical role in feedback regulation. Compared with Ero1α, however, Ero1β is loosely regulated, consistent with its role as a more active oxidase when massive oxidative power is required.     

Regulator or Driving Force? The Role of Turgor Pressure in Oscillatory Plant Cell Growth

Turgor generates the stress that leads to the expansion of plant cell walls during cellular growth. This has been formalized by the Lockhart equation, which can be derived from the physical laws of the deformation of viscoelastic materials. However, the experimental evidence for such a direct correlation between growth rate and turgor is inconclusive. This has led to challenges of the Lockhart model. We model the oscillatory growth of pollen tubes to investigate this relationship. We couple the Lockhart equation to the dynamical equations for the change in material properties. We find that the correct implementation of the Lockhart equation within a feedback loop leading to low amplitude oscillatory growth predicts that in this system changes in the global turgor do not influence the average growth rate in a linear manner, consistent with experimental observations. An analytic analysis of our model demonstrates in which regime the average growth rate becomes uncorrelated from the turgor pressure.     

The hand of man first then Santa Rosalia’s blessing: a critical examination of the supposed criticism by Samraoui (2017)

Samraoui (J Insect Conserv.  https://doi.org/10.1007/s10841-017-9966-2, 2017) claims that he shows evidence that our conservation plan of Urothemis edwardsii has failed and that natural dispersal was the only cause of the recent rapid range expansion of the species in Northeast Algeria. Here, we show that his analysis is biased, many of his arguments are erroneous and strongly contradictory, many key studies are dismissed, and the few data used as evidence to refute our conclusions rather confirm them. We also provide data to prove that our conservation plan did not cause any harm to the source population by comparing exuviae-based estimation of population size in 2012 and 2016. We discuss the need for future monitoring and management and highlight that the recommendations of Samraoui (J Insect Conserv, 2017) are misleading, and thus are unlikely to bring us closer to an effective long-term conservation of the species in the region. Beyond our criticism, we explain why we should not dismiss the direct and indirect implications of final instar larvae translocation in successful colonization of odonates in particular, which could also be applied to aquatic insects in general.