Les leçons du premier institut d’études avancées d’Afrique
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LolA and LolB are conserved in Bacteroidota and are crucial for gliding motility and Type IX secretion
Lipoproteins are key outer membrane (OM) components in Gram-negative bacteria, essential for functions like membrane biogenesis and virulence. Bacteroidota, a diverse and widespread phylum, produce numerous OM lipoproteins that play vital roles in nutrient acquisition, Type IX secretion system (T9SS), and gliding motility. In Escherichia coli, lipoprotein transport to the OM is mediated by the Lol system, where LolA shuttles lipoproteins to LolB, which anchors them in the OM. However, LolB homologs were previously thought to be limited to γ- and β-proteobacteria. This study uncovers the presence of LolB in Bacteroidota and demonstrates that multiple LolA and LolB proteins co-exist in various species. Specifically, in Flavobacterium johnsoniae, LolA1 and LolB1 transport gliding motility and T9SS lipoproteins to the OM. Notably, these proteins are not interchangeable with their E. coli counterparts, indicating functional specialization. Some lipoproteins still localize to the OM in the absence of LolA and LolB, suggesting the existence of alternative transport pathways in Bacteroidota. This points to a more complex lipoprotein transport system in Bacteroidota compared to other Gram-negative bacteria. These findings reveal previously unrecognized lipoprotein transport mechanisms in Bacteroidota and suggest that this phylum has evolved unique strategies to manage the essential task of lipoprotein localization.
Complexity of leaf trait covariation for mangrove species
The leaf economics spectrum (LES) has been proposed as a framework for understanding leaf resource-investment and plant growth strategies, but it is scarcely examined in mangrove communities. This study investigates LES patterns in mangrove communities to examine whether the trait coordination spectrum, if it exists, is associated with plant growth strategies. By conducting a comprehensive sampling across a wide range of mangrove species in China, we confirmed the presence of LES across mangrove species, and found that true mangroves generally exhibit a more conservative strategy characterized by higher leaf mass per area (LMA) and lower leaf nutrient concentrations compared to mangrove associates. We also observed considerable intraspecific variation in traits, particularly in LMA. In some cases, fast-growing species exhibited higher LMA and lower leaf nutrient concentrations than slow-growing species. Fast-growing species also showed higher leaf thickness than slow-growing species, but no difference in leaf density between them, suggesting that LMA composition is important in understanding trait coordination and its link with plant growth strategies in mangrove communities. Our findings highlight a complex link between trait coordination and plant growth strategies in mangrove species.
Numerical simulation of spatial wind fields in Xumishan Grottoes over complex terrain
Windy weather frequently occurs in Northwest China, and wind erosion is a typical issue for stone carvings in the caves. In the present study, computational fluid dynamics (CFD) simulations relying on steady 3D Reynolds-averaged Navier-Stokes (RANS) equations were used to simulate the spatial wind field over complex terrain with field measurement validation. This study has the following two aims: (1) to evaluate the accuracy of wind fields simulations with the Interpolated Multiscale Profile (IMP) method over complex terrain; and (2) to provide spatial wind field data of Xumishan Grotto Zone under neutrally stratified atmospheric boundary layer (ABL) over complex terrain. Unmanned aerial vehicle (UAV) oblique photogrammetry and multirotor UAV technology provide application scenarios for the establishment of a high-precision digital model and the determination of accurate inlet boundary conditions. By compiling user-defined functions (UDF) and using the block interpolation method, this method addresses the overestimation of the inlet wind velocity caused by the large elevation difference of the inlet over complex terrain. The results show that the 3D steady RANS simulation based on the IMP method can reasonably and accurately simulate spatial wind fields over complex terrain. This study also provides spatial wind fields data for addressing stone carving erosion caused by strong winds in semi-open Grottoes.
Clinico-pathological factors predicting pathological response in early triple-negative breast cancer
Pathological complete response (pCR) after neoadjuvant chemoimmunotherapy (NACi) is associated with improved patient outcomes in early triple-negative breast cancer (TNBC). This study aimed to identify factors associated with pCR after NACi. This cohort included all patients with stage II-III TNBC treated with NACi who underwent surgery at Institut Curie hospitals between 08/2021-06/2023. Among 208 patients, the overall pCR rate was 70% and was similar in ER < 1% (69%) and ER-low TNBC (73%, p = 0.6). In a multivariate model, Ki-67 ≥ 30% (OR 5.19 [1.73–17.3]), centralized TILs ≥ 30% (OR = 3.08 [1.42–7.04]), absence of DCIS at initial biopsy (OR = 2.56 [1.08–6.25]) and germline mutations in homologous recombination genes (OR = 9.50 [2.37–67.7]) remained strong independent predictors of pCR. These findings may guide treatment decisions in patients with TNBC undergoing NACi. Almost all patients with germline mutations in HR genes achieved pCR, supporting de-escalation trials. We suggest that ER-low tumors should be managed as TNBC tumors.
Regional patterns of wild animal hunting in African tropical forests
Wildlife contributes to the diets, livelihoods and socio-cultural activities of people worldwide; however, unsustainable hunting is a major pressure on wildlife. Regional assessments of the factors associated with hunting offtakes are needed to understand the scale and patterns of wildlife exploitation relevant for policy. We synthesized 83 studies across West and Central Africa to identify the factors associated with variation in offtake. Our models suggest that offtake per hunter per day is greater for hunters who sell a greater proportion of their offtake; among non-hunter-gatherers; and in areas that have better forest condition, are closer to protected areas and are less accessible from towns. We present evidence that trade and gun hunting have increased since 1991 and that areas more accessible from towns and with worse forest condition may be depleted of larger-bodied wildlife. Given the complex factors associated with regional hunting patterns, context-specific hunting management is key to achieving a sustainable future.
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