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Studies investigating chemistry students’ understanding of intermolecular forces have listed alternative conceptions; however, there is a call to investigate why students might have these alternative conceptions. This study describes how second semester general chemistry students predict the location of dipole–dipole forces between two molecules from a resource activation perspective. During interviews, 18 students were asked to describe the location of forces between four pairs of molecules. Students relied on one or more of the following approaches in determining location: (1) attraction between opposite charges, (2) electronegativity differences, (3) biggest electronegativity values, (4) largest atomic size, and (5) molecular shape. Each student’s approach is characterized by the resources being activated and, in particular, students’ use of electronegativity. Students’ use of electronegativity varied, including comparing electronegativity values between unbonded atoms within a molecule and between atoms present on different molecules. The findings suggest future research directions and teaching implications that could improve students’ understanding of intermolecular forces including the explicit integration and assessment of the concepts of electronegativity and intermolecular forces. 

Biomolecular condensates have emerged as major drivers of cellular organization. It remains largely unexplored, however, whether these condensates can impart mechanical function(s) to the cell. The heterochromatin protein HP1α (Swi6 in Schizosaccharomyces pombe) crosslinks histone H3K9 methylated nucleosomes and has been proposed to undergo condensation to drive the liquid-like clustering of heterochromatin domains. Here, we leverage the genetically tractable S. pombe model and a separation-of-function allele to elucidate a mechanical function imparted by Swi6 condensation. Using single-molecule imaging, force spectroscopy, and high-resolution live-cell imaging, we show that Swi6 is critical for nuclear resistance to external force. Strikingly, it is the condensed yet dynamic pool of Swi6, rather than the chromatin-bound molecules, that is essential to imparting mechanical stiffness. Our findings suggest that Swi6 condensates embedded in the chromatin meshwork establish the emergent mechanical behavior of the nucleus as a whole, revealing that biomolecular condensation can influence organelle and cell mechanics. 

Microbial communities, and their ecological importance, have been investigated in several habitats. However, so far, most studies could not describe the closest microbial interactions and their functionalities. This study investigates the co-occurring interactions between fungi and bacteria in plant rhizoplanes and their potential functions. The partnerships were obtained using fungal-highway columns with four plant-based media. The fungi and associated microbiomes isolated from the columns were identified by sequencing the ITS (fungi) and 16S rRNA genes (bacteria). Statistical analyses including Exploratory Graph and Network Analysis were used to visualize the presence of underlying clusters in the microbial communities and evaluate the metabolic functions associated with the fungal microbiome (PICRUSt2). Our findings characterize the presence of both unique and complex bacterial communities associated with different fungi. The results showed that Bacillus was associated as exo-bacteria in 80 % of the fungi but occurred as putative endo-bacteria in 15 %. A shared core of putative endo-bacterial genera, potentially involved in the nitrogen cycle was found in 80 % of the isolated fungi. The comparison of potential metabolic functions of the putative endo- and exo-communities highlighted the potential essential factors to establish an endosymbiotic relationship, such as the loss of pathways associated with metabolites obtained from the host while maintaining pathways responsible for bacterial survival within the hypha. 

The present study compares for the first time the effects of h-MoO 3 and α-MoO 3 against two fungal strains: Aspergillus niger and Aspergillus flavus . The h-MoO 3 nanoparticles were more toxic to both fungi than α-MoO 3 . The toxic effects of h-MoO 3 were more pronounced toward A. flavus , which presented a growth inhibition of 67.4% at 200 mg L −1 . The presence of the nanoparticles affected drastically the hyphae morphology by triggering nuclear condensation and compromising the hyphae membrane. Further analysis of the volatile organic compounds (VOCs) produced by both fungi in the presence of the nanomaterials indicated important metabolic changes related to programmed cell death. These nanomaterials induced the production of specific antifungal VOCs, such as β-Elemene and t-Cadinol, by the fungi. The production of essential enzymes involved in fungal metabolism, such as acid phosphatase, naphthol-As-BI-phosphohydrolase, β-galactosidase, β-glucosidase and N -acetyl-β-glucosaminidase, reduced significantly in the presence of the nanomaterials. The changes in enzymatic production and VOCs corroborate the fact that these nanoparticles, especially h-MoO 3 , exert changes in the fungal metabolism, triggering apoptotic-like cell death responses in these fungi.