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Widening global variability in grassland biomass since the 1980s
(Nature Research, 2024-10) MacDougall, Andrew S.; Esch, Ellen; Chen, Qingqing; Carroll, Oliver; Bonner, Colin; Ohlert, Timothy; Siewert, Matthias; Sulik, John; Schweiger, Anna; Borer, Elizabeth T.; Naidu, Dilip; Bagchi, Sumanta; Hautier, Yann; Wilfahrt, Peter; Larson, Keith; Olofsson, Johan; Cleland, Elsa; Muthukrishnan, Ranjan; O'Halloran, Lydia; Alberti, Juan; Anderson, T. Michael; Arnillas, Carlos A.; Bakker, Jonathan D.; Barrio, Isabel C.; Biederman, Lori; Boughton, Elizabeth H.; Brudvig, Lars A.; Bruschetti, Martin; Buckley, Yvonne; Bugalho, Miguel N.; Cadotte, Marc W.; Caldeira, Maria C.; Catford, Jane A.; D'Antonio, Carla; Davies, Kendi; Daleo, Pedro; Dickman, Christopher R.; Donohue, Ian; Dupre, Mary Ellyn; Elgersma, Kenneth; Eisenhauer, Nico; Eskelinen, Anu; Estrada, Catalina; Fay, Philip A.; Feng, Yanhao; Gruner, Daniel S.; Hagenah, Nicole; Haider, Sylvia; Harpole, W. Stanley; Hersch-Green, Erika; Jentsch, Anke; Kirkman, Kevin; Knops, Johannes M.H.; Laanisto, Lauri; Lannes, Luciola S.; Laungani, Ramesh; Lkhagva, Ariuntsetseg; Macek, Petr; Martina, Jason P.; Mcculley, Rebecca L.; Melbourne, Brett; Mitchell, Rachel; Moore, Joslin L.; Morgan, John W.; Muraina, Taofeek O.; Niu, Yujie; Paertel, Meelis; Peri, Pablo L.; Power, Sally A.; Price, Jodi N.; Prober, Suzanne M.; Ren, Zhengwei; Risch, Anita C.; Smith, Nicholas G.; Sonnier, Gregory; Standish, Rachel J.; Stevens, Carly J.; Tedder, Michelle; Tognetti, Pedro; Veen, G.F. (Ciska); Virtanen, Risto; Wardle, Glenda M.; Waring, Elizabeth; Wolf, Amelia A.; Yahdjian, Laura; Seabloom, Eric W.
Global change is associated with variable shifts in the annual production of aboveground plant biomass, suggesting localized sensitivities with unclear causal origins. Combining remotely sensed normalized difference vegetation index data since the 1980s with contemporary field data from 84 grasslands on 6 continents, we show a widening divergence in site-level biomass ranging from +51% to −34% globally. Biomass generally increased in warmer, wetter and species-rich sites with longer growing seasons and declined in species-poor arid areas. Phenological changes were widespread, revealing substantive transitions in grassland seasonal cycling. Grazing, nitrogen deposition and plant invasion were prevalent in some regions but did not predict overall trends. Grasslands are undergoing sizable changes in production, with implications for food security, biodiversity and carbon storage especially in arid regions where declines are accelerating.
Acute animal toxicity and genotoxicity of obliquumol, a potential new framework antifungal compound isolated from Ptaeroxylon obliquum (Rutaceae) leaf extracts
(Elsevier, 2024-09) Ramadwa, Thanyani Emelton; McGaw, Lyndy Joy; Madikizela, Balungile; Eloff, Jacobus Nicolaas
Obliquumol (12-O-acetylptaeroxylinol) isolated from Ptaeroxylon obliquum leaves has excellent antifungal activity and low cellular toxicity. As a next step in the potential development of a framework antifungal product, the present work investigated the acute animal toxicity of obliquumol according to OECD 423 guidelines. Furthermore, the genotoxicity of P. obliquum acetone leaf extracts, fractions (hexane, chloroform and 30 % H2O in MeOH) and isolated compounds (obliquumol and a mixture of lupeol and β-amyrin) was determined using Ames test. . A single dose of obliquumol was orally administered to mice at levels of 50, 300 and 2000 mg/kg and observed for 14 days. The three S. typhimurium tester strains TA 98, TA 100 and TA 102 were used without metabolic activation to determine the genotoxicity. Even at the highest dose of obliquumol, the mass, behaviour and food intake of the animals were not affected. Gross necropsy and histopathological analysis on organs indicated hardly any effects. No samples had genotoxic activity against the S. typhimurium strains tested. Obliquumol had an LD50 >2000 mg/kg since there were no mortalities after 14 days. This encourages the possible development of a new class of antifungal compounds from the obliquumol framework.
Applying the intersection between defence of the inherent requirements of the job and the duty to provide reasonable accommodation for persons with disabilities in the workplace : Damons v City of Cape Town
(Routledge, 2024) Ngwena, Charles; charles.ngwena@up.ac.za
In Damons v City of Cape Town (2022), by a majority, the Constitutional Court held that the inherent requirements of the job defence in s 6(2)(b) of the Employment Equity Act is a complete defence to a charge of unfair discrimination in respect of an employee who has no capacity to perform the job in question due to a disability that cannot be rehabilitated or reasonably accommodated. By contrast, in a sole dissent, Pillay AJ held that s 6(2)(b) is not a complete defence where the employer ought to have created a new position to fit the capacities of the employee as a reasonable accommodation measure. This commentary explores the implications of the Damons case and appraises the divergent approaches of the Constitutional Court.
Objective classification of countermovement jump force-time curve modality : within athlete-consistency and associations with jump performance
(Routledge, 2024) Bayne, Helen; Cockcroft, John; Robyn, Aneurin; Louw, Quinette; helen.bayne@up.ac.za
Force-time curves produced during a countermovement jump (CMJ) have traditionally been classified by visual observation as either unimodal (one concentric phase peak) or bimodal (two peaks). The association between CMJ modality and jump performance remains unclear and future studies may benefit from standardising and expanding modality classification. This study described a numerical method based on the timing and relative magnitude of concentric force-time curve prominences. Adult male elite rugby union players (n = 214) performed six CMJs on a force-instrumented treadmill and an algorithm using turning-point logic was applied to categorise jumps and define modality sub-groups. A sensitivity analysis demonstrated that the minimum prominence threshold (MPT) affected categorisation, as the proportion of bimodal jumps decreased with each 1% increase in MPT. Within-athlete consistency was also affected; between 43% and 63% of participants were consistently categorised as bimodal or unimodal depending on the selected MPT. Modified reactive strength index (RSImod), but not jump height or take-off momentum, was greater in unimodal jumps. Take-off momentum and RSImod were greater in subcategories where maximum force occurred early in the concentric phase. Future research should implement objective classification methods to enhance transparency and comparability and consider subcategories to investigate CMJ force production strategies.
HIV-helminth co-infections and immune checkpoints : implications for cancer risk in South Africa
(MDPI, 2025-03) Damane, Botle Precious; Mulaudzi, Thanyani Victor; Kader, Sayed Shakeel; Naidoo, Pragalathan; Dlamini, Zodwa; Mkhize-Kwitshana, Zilungile Lynette; zodwa.dlamini@up.ac.za
South Africa has the highest HIV prevalence globally, often co-occurring with helminth infections in impoverished regions. The coexistence of these infections leads to immunological interactions, potentially enhancing oncogenesis by upregulating immune checkpoint molecules (ICs) among other effects. Notably, most ICs are overexpressed in cancer and correlated with its progression. Helminth infections trigger Th2-type immunity, increasing immunosuppressive M2 macrophages, regulatory T cells, and associated IC molecules. PD-L2 is reported to contribute to Th2-type immunity induced by helminth infections. Similarly, TIM-3, elevated during chronic viral infections, induces a similar immunosuppressive profile. CTLA-4 and PD-1 impact T-cell function by interacting with CD28, crucial for T-cell function. CD28 is downregulated in chronic infections and cancer. This study investigated the impact of HIV-helminth co-infection on co-stimulatory and co-inhibitory molecule profiles associated with antitumor immunity. Using 78 serum samples collected from March 2020 to May 2021, participants were categorized into uninfected control (no HIV and helminth infections), HIV-infected, helminth-infected, and HIV-helminth co-infected groups. Multiplex immune regulatory molecule assay analysis was conducted. The data were analyzed using multivariate regression analysis and adjusted for confounders (age, gender, BMI, ART, supplements, and other chronic diseases). The uninfected control group was used as the baseline reference group for analysis. HIV-infected individuals had higher PD-1 (adjusted β = 0.12, p = 0.034) and TIM-3 (adjusted β = 23.15, p = 0.052) levels, with the latter showing a trend toward significance. However, lower CD28 levels (adjusted β = −651.95, p = 0.010) were observed. Helminth-infected individuals had higher TIM-3 levels (adjusted β = 20.98, p = 0.020). The co-infected group had higher PD-1 (unadjusted β = 0.18, p = 0.0046) and PD-L2 (adjusted β = 7.95, p = 0.033) levels. A significant decrease in CD28 profile was observed across all infected groups: HIV-infected (adjusted β = −651.95, p = 0.010), helminth-infected (adjusted β = −674.32, p = 0.001), and co-infected (adjusted β = −671.55, p = 0.044). The results suggest that HIV-helminth co-infections alter immune checkpoint markers, potentially increasing cancer risk by promoting an immunosuppressive microenvironment that hinders anti-cancer immunity. CD28’s downregulation underscores immune inefficiency in chronic diseases. Addressing these co-infections is crucial for improving HIV care and potentially reducing cancer risks through targeted strategies.