Eukaryotic genomes are organized dynamically through the repositioning of nucleosomes. Isw2 is an enzyme that has been previously defined as a genome-wide, non-specific nucleosome spacing factor. Here, we show that Isw2 instead acts as an obligately targeted nucleosome remodeler in vivo through physical interactions with sequence-specific factors. We demonstrate that Isw2- recruiting factors use small and previously uncharacterized epitopes, which direct Isw2 activity through highly conserved acidic residues in the Isw2 accessory protein Itc1. This interaction orients Isw2 on target nucleosomes, allowing for precise nucleosome positioning at targeted loci. Finally, we show that these critical acidic residues have been lost in the Drosophila lineage, potentially explaining the inconsistently characterized function of Isw2-like proteins. Altogether, these data suggest an 'interacting barrier model' where Isw2 interacts with a sequence-specific factor to accurately and reproducibly position a single, targeted nucleosome to define the precise border of phased chromatin arrays.

Highlights d Brief heat shock triggers DNA damage in spermatocytes d Heat-induced DNA damage is SPO-11 independent and negatively impacts fertility d Tc1/mariner transposons mobilize in the male germline after heat shock d Female germline represses heat-induced DNA damage and Tc1 mobilization

Green roofs are a way for cities to mitigate environmental stressors, such as heatwaves and droughts. However, these environmental stressors can adversely affect green roof vegetation, causing challenges for plant growth and survival and subsequently reducing the ability of green roof systems to deliver critical ecosystem services, such as heat mitigation and nutrient cycling. Plant-associated microbes may facilitate the resilience and tolerance of green roof vegetation to climate-associated stress. However, despite their crucial role in plant growth and survival in natural ecosystems, there has been little research on plant-associated microbes in green roof systems. Plant choice on green roofs may also determine which microbes established in green roof growing media, and particular plant-microbial combinations may be more resilient to environmental stress. This project sought to characterize soil microbial community composition on green roofs across New York City with different plant palettes and assess how different combinations of green roof plant species and root-associated microbial assemblages responded to isolated and simultaneous heat and drought treatments. We surveyed green roofs planted with either Sedum species or with a mixedvegetation palette (i.e., wildflowers, grasses, and succulents). We found that mixedvegetation and Sedum green roofs had distinct soil bacterial and fungal communities (p < 0.0001) with a higher relative abundance of mycorrhizal fungi on mixed-vegetation roofs, and higher pathogen loads on Sedum roofs. Concurrently, we conducted a greenhouse experiment in which plants were grown from seed with live inocula collected from the two different types of vegetation on the green roofs we surveyed. Hoch et al. Green Roof Soil Microbial Communities We observed that plant species, soil inoculum, and abiotic stress treatment was correlated with shifts in soil fungal communities. This study demonstrated that soil microbial assemblages on green roofs are linked to the roof vegetation, and that they may facilitate green roof plants' tolerance and resilience to environmental stressors.

SUMMARY Regulation of chromatin structure is essential for controlling access of DNA to factors that require association with specific DNA sequences. Here we describe the development and validation of engineered chromatin remodeling proteins (E-ChRPs) for inducing programmable changes in nucleosome positioning by design. We demonstrate that E-ChRPs function both in vitro and in vivo to specifically reposition target nucleosomes and entire nucleosomal arrays. We show that induced, systematic positioning of nucleosomes over yeast Ume6 binding sites leads to Ume6 exclusion, hyperacetylation, and transcriptional induction at target genes. We also show that programmed global loss of nucleosome-free regions at Reb1 targets is generally inhibitory with mildly repressive transcriptional effects. E-ChRPs are compatible with multiple targeting modalities, including the SpyCatcher and dCas9 moieties, resulting in high versatility and enabling diverse future applications. Thus, engineered chromatin remodeling proteins represent a simple and robust means to probe and disrupt DNA-dependent processes in different chromatin contexts.

Bioswales and other forms of green infrastructure can be effective means to reduce environmental stresses in urban ecosystems; however, few studies have evaluated the ecology of these systems, or the role that plant selection and microbial assembly play in their function. For the current study, we examined the relationship between plant transpiration rates for five commonly planted herbaceous species in three bioswales in New York City, as well as bioswale soil microbial composition and soil chemistry. Soils were sampled near individual plants, with distinction made between upper (bioswale inlet) and lower slopes (bioswale outlet). We found high variation in transpiration rates across species, and that Nepeta × faassenii was the highest conductor (13.65 mmol H2O m–2s–1), while Panicum virgatum was the lowest conductor (2.67 mmol H2O m–2s–1) (p < 0.001). There was significant variation in percent N of leaves and soil, which did not relate to the higher water conductance in bioswales. Significantly higher C, N, and water content on the high end of bioswale slopes suggest storm water run-off is mostly absorbed on the inlet side. Bacterial and fungal communities were significantly clustered by bioswale and by plant species within each bioswale implying there are micro-environmental controls on the soil microbial composition, and that plant composition matters for microbial assemblages within bioswales. Plants with higher transpiration rates were associated with greater fungal and bacterial diversity at the level of the bioswale and at scale of the individual plant, suggesting a possible link between plant physiological traits and soil microbial communities. These data suggest that the specific plant palette selected for planting bioswales can have deterministic effects on the surrounding microbial communities which may further influence functions such as transpiration and nutrient cycling. These results may have implications for bioswale management to improve urban water quality and reduce stress on sewage systems after storm events by revising plant species palette selection based on the functional consequences of plant-microbial associations in engineered green infrastructure.