Rhodes University

Trypanosoma cruzi and Leishmania spp. are the protozoan parasites responsible for Chagas disease and leishmaniasis. The treatment of these neglected diseases relies on repurposed drugs and faces several challenges including high toxicity, and the emergence of resistant strain. Therefore, there is a constant demand for promising antiparasitic agents. The present work aimed to investigate seventeen prepared N1,N4-bisbenzylbutane-1,4-diamines against recombinant T. cruzi and L. infantum as well as their inhibitory effects against the T. cruzi recombinant trypanothione reductase (TcTR). N1,N4-bis(4-chlorobenzyl)butane-1,4-diamine showed significant trypanocidal activity with an IC50 of 6.0±0.9μM with a selectivity index of 4.3. This compound was more active than the positive control, benznidazole (IC50 of 14.6). It moderately inhibited TcTR with an IC50 of 55.6±18.6μM. N1,N4-bis(4-chlorobenzyl)butane-1,4-diamine also inhibited L. infantum with an IC50 of 19.3±1.2μM (SI of 3.4). N1,N4-bis((E)-3-(2-methoxyphenyl)allyl)butane-1,4-diamine exhibited potent inhibitory effect against T. cruzi (2.4±0.3μM); However, it also turned out to be highly cytotoxic to the L929 fibroblast cell line. Its inhibitory effect against TcTR was also significant, with an IC50 of 3.9±1.9μM. Alongside the two diamines, nine other synthesized derivatives displayed antitrypanosomal activity with IC50 ranging from 8 to 150μM. Concerning the leishmanicidal effects, all tested compounds were moderately active. Moreover, during in silico studies of the active compounds using TcTR (PDB ID 4NEW), N1,N4-bis((E)-3-(2-methoxyphenyl)allyl)butane-1,4-diamine emerged as the most promising candidate, displaying both strong binding affinity and significant biological activity.

Spawning aggregations are critical reproductive events for many reef fishes around the world, yet they are highly vulnerable to exploitation, making effective management essential for sustaining fisheries and conserving aggregation-forming species. In Palau, a proposed management plan seeks to protect a longnose emperor ( Lethrinus olivaceus ) spawning aggregation during the full moon at an outer reef corner (Mutiaur). We identified migration pathways, examined environmental and biological drivers of aggregation timing, quantified depth use, and evaluated the adequacy of proposed protection measures. An array of 32 acoustic receivers was used to track 16 longnose emperors from 2022 to 2025 across Mutiaur and surrounding habitats. Presence at the aggregation site was significantly influenced by lunar phase, day of year, time of day, tidal height, and seawater temperature. Lunar phase was the strongest predictor, with peak detections from three days before to eight days after the new moon, contradicting the full-moon timing assumed in the management plan. Aggregation presence was highest from January to April and primarily during nighttime hours. Migratory pathways followed the outer reef, with individuals traveling up to 13 km to reach Mutiaur. High detections outside the proposed protected area indicate that current closure boundaries are insufficient. Effective protection will require shifting temporal measures to the new-moon period and expanding the protected area from 0.14 km² to include at least the entire reef corner (0.22 km²). These results highlight the value of species-specific movement data for designing spawning aggregation protections and contribute to broader efforts to improve aggregation-based fisheries management globally. Longnose emperor spawning aggregations peaked around the new moon. Presence at the aggregation site was highest from January to April and at night. Fish migrated up to 13 km along outer reef corridors to the aggregation site. Proposed protection measures do not match observed patterns. Effective protection requires new-moon timing and full reef corner coverage.

A temperature below or above the optimum can reduce the rate of photosynthesis in higher plants, which in turn decreases metabolite precursor pools for the biosynthesis of secondary metabolites. The aim of this study was to determine the effects of seasonal changes in water temperature on α-tocopherol accumulation in pepper (Capsicum annuum L.) fruits from an aquaponic system. A portable dissolved oxygen meter was used to measure water temperature and high-performance liquid chromatography was used to determine the levels of α-tocopherol accumulation. Temperature of the fish water ranged from 8.3 °C to 13.8 °C in winter and from 20.2 °C to 25.8 °C in summer. Water temperature in winter was significantly different (p < 0.05) from that in summer. α-Tocopherol accumulation in pepper fruits differed significantly (p < 0.05) between winter (0.77 ± 0.13%) and summer (1.64 ± 0.21%). Changes in water temperature due to seasonality caused variations in α-tocopherol accumulation in pepper fruits, with fruits in the warmer season (summer) showing a higher accumulation of α-tocopherol. The warmer season is therefore a better period for α-tocopherol biosynthesis.

Abstract The merger shocks generated by the collision of galaxy clusters elevate the pressure within the intracluster medium, significantly influencing the evolution of embedded cluster galaxies. We detect a merger shock (Mach number ∼1.3) on the northwest side of the closest rich galaxy cluster Norma (A3627), using XMM-Newton and Chandra data. The textbook ram pressure stripping (RPS) galaxy ESO 137-001 appears to be located in the postshock region. The shock boosts RPS and may induce the formation of the brightest known X-ray tail behind a cluster late-type galaxy. Another prominent head–tail radio galaxy, ESO 137-007, with one of the longest radio continuum tails (>500 kpc), is also likely in the postshock region. The shock may have reversed the upstream jet to a one-sided radio head–tail morphology. Moreover, the shock can strip and roll the jet cocoon into a vortex ring structure like a “smoke ring” behind the end of the jet as observed by the ASKAP data. Therefore, the cluster merger shock can remarkably change cluster galaxies. Furthermore, Norma is the second brightest non-cool-core cluster following the Coma cluster, with a cool core remnant on its southeast side. Its original cool core may be disrupted by cluster mergers and/or active galactic nuclei.

Illegal solid waste dumping is a key urban sustainability challenge due to increased urbanisation and human consumption, but its prevalence and impacts across a socially differentiated gradient are seldom considered. We used street and off-street road surveys to examine the extent of illegal solid waste dumping across an income gradient in two medium-sized towns of Makhanda and Knysna in South Africa. We enumerated all dumpsites encountered in low- and high-income areas, recorded their GPS coordinates, and visually estimated size and composition using a standardised typology. We encountered 215 illegal solid waste dumpsites unevenly distributed by town (155 in Makhanda and 60 in Knysna) and income status, with the majority located in low-income areas compared to high-income areas. Most illegal solid waste dumpsites in low-income areas were small and located along roadsides and vacant plots. In both towns, illegal solid waste dumpsites were dominated by household and garden waste. The findings suggest that social differentiation matters in illegal solid waste dumping and should be factored into service provision strategies for ensuring environmental justice. We recommend that (i) municipalities should consider income heterogeneity in designing effective and equitable waste management plans, (ii) the national government should consider additional human and financial support to municipalities for efficient and equitable residential waste management, (iii) waste recycling at source (within households) should be mainstreamed in waste management strategies, and (iv) cleanup campaigns should be considered as a short-term solution to manage existing illegal solid waste dumpsites.

The biological control and invasion sciences are long-standing research fields that have accrued enormous fundamental and applied interest. However, their theoretical and practical integration remains in its infancy. Utilizing an expert elicitation process with participants spanning these sciences, we identify conceptual parallels and future opportunities to strengthen links and address future challenges in both fields. We found that the biological control and invasion sciences face pervasive context-dependencies that must be understood to improve outcome predictions, including climatic changes, spatiotemporal scales, and 'ecological surprises'. Both sciences would further benefit from terminological streamlining to improve communication, sharing of emerging technologies, and mitigation of the taxonomic decline. The two fields are strongly affected by social perceptions and awareness by decision makers, requiring more effective engagement and translation efforts. Our exercise promotes cross-cutting interdisciplinary advances to improve understanding of fundamental ecological and evolutionary processes, socio-ecological challenges, and management efficacy across the biological control and invasion sciences.

The SARS-CoV-2 papain-like protease (PLpro) is an essential viral enzyme that promotes viral polyprotein processing while simultaneously suppressing the host innate immune response, which makes it a primary target for developing antiviral drugs. The present study employs a comprehensive approach integrating untargeted metabolomic profiling, in silico molecular docking and dynamics simulations, Molecular Mechanics Generalized Born Surface Area (MM-GBSA) energetic assessments, and biochemical enzyme assays. This integrated method aims to discover natural PLpro inhibitors from two ethnomedicinal plants, Lippia javanica and Acorus calamus, which have long been utilized in African traditional medicine to treat respiratory diseases. Comprehensive metabolite profiling using untargeted Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) and Global Natural Products Social (GNPS) molecular networking revealed flavonoid glucuronides and phenylpropanoid derivatives as the major constituents in both plant species. In situ histochemical staining further offered spatial validation of phenolic- and lignin-associated tissues, supporting the phenolic-dominated molecular families detected by GNPS molecular networking. In silico evaluation of six selected compounds demonstrated spontaneous and thermodynamically favorable binding to PLpro, with ΔG_bind values ranging from -5.63 to -6.43 kcal/mol. Catechin-7-glucoside emerged as the lead compound, establishing multiple hydrogen bond networks with Asp164, Gln269, Tyr264, and Asn267, supplemented by hydrophobic engagement with Pro247 and Pro248, and π-π stacking with the blocking loop 2 (BL2 loop). Molecular dynamics simulations confirmed the stability of the protein-ligand complexes. Biochemical enzyme assays confirmed concentration-dependent inhibition of PLpro proteolytic and deubiquitinating activity by both crude plant extracts and isolated bioactive compounds. However, S-adenosyl-methionine showed comparatively high PLpro proteolytic activity (IC50 5.872 µM) compared to catechin-7-glucoside, with an IC50 of 7.493 µM, exhibiting efficacy similar to the reference inhibitor GRL0617. Both the extracts of L. javanica and A. calamus have shown significant inhibitory activity while maintaining cell viability in Human embryonic kidney 293T cell (HEK293T) culture models, indicating a favorable safety profile of the tested concentrations. Based on these results, catechin-based polyphenols and phenylpropanoid derivatives appear as promising lead compounds for the development of PLpro inhibitors. To progress toward therapeutic use, further work is necessary in pharmacokinetics, structural optimization, and antiviral validation in cell models.