The plant hormone gibberellin (GA4) regulates numerous developmental processes. Within the root, GA4 controls growth, in part, by controlling the extent of cell elongation. The nlsGPS1 FRET biosensor revealed a GA4 gradient within the Arabidopsis root growth zones, with GA4 levels correlating with cell length. We developed a multiscale mathematical model to understand how biosynthesis, catabolism, and transport create the GA4 distribution within the root growth zones. The model predicted that phloem delivery of the biosynthetic intermediate GA12 contributes to higher levels of bioactive GA4 in the elongation zone, with the GA4 synthesis pattern being further modified by local GA12 synthesis in the quiescent center region and the spatial distribution of biosynthesis enzymes (GA20ox and GA3ox). Model predictions suggested that while GA20ox and GA3ox transcript is present throughout the growth zones, these enzymes are inactive in the dividing cells, which explains steep GA4 gradients observed in the GA3ox overexpression line and improves agreement between model predictions and data in wildtype. The model suggested that the GA4 gradient also depends on a balance of diffusion through plasmodesmata and catabolism. Both model predictions and biosensor data demonstrated that plasmodesmatal diffusion enables a more gradual GA4 gradient, with higher diffusion antagonizing the GA4 gradient. Model predictions suggested that catabolism limits GA4 levels, which we validated via biosensor imaging in the ga2oxhept mutant. In conclusion, our results suggest that local GA4 synthesis combines with diffusion and catabolism to create a spatial GA4 gradient that provides positional information and patterns cell elongation.

The solute carrier (SLC)29A3 exports nucleosides from lysosomes into the cytosol, maintaining solute homeostasis and providing metabolic intermediates for cellular processes. Loss-of-function mutations in SLC29A3 cause H syndrome, characterized by histiocytosis, hyperinflammation, and immunodeficiency. While dysfunctions in various cell types contribute to H syndrome and to SLC29A3 deficiency in mice, the mechanisms driving hyperinflammation and immunodeficiency are incompletely understood. Remarkably, the possible role played by dendritic cells (DCs), the most efficient antigen (Ag)-presenting cells and the main cellular link between innate and adaptive immunity, remains unknown. We show that, in murine DCs, SLC29A3 is recruited to phagosomes after bacterial capture, maintains phagosomal pH homeostasis, and ensures optimal antimicrobial phagosomal signaling to the production of IL-6, IL-12, pro-IL-1β, and CCL22. In addition, SLC29A3 promotes Ag presentation on MHC-II molecules to initiate adaptive immune responses. Notably, SLC29A3 supports the activity of the lysosomal calcium channel TRPML1, promoting the nuclear translocation of transcription factor TFEB and inducing autophagy, a major anti-inflammatory mechanism. Overexpression of human SLC29A3, but not the transport mutant G437R, in SLC29A3-deficient murine DCs restores cytokine production in response to bacterial phagocytosis, suggesting that SLC29A3 transport activity is required to drive phagosomal signaling. Our data suggest that SLC29A3 supports and controls immune function in DCs by promoting effective antimicrobial signaling and Ag presentation, and inducing autophagy. Our findings also uncover a TRPML1-dependent mechanism by which SLC29A3 activates TFEB and suggest that defects in phagosomal antibacterial signaling, TFEB activation, and autophagy may contribute to immunodeficiency and hyperinflammation in SLC29A3 disorders.

Testosterone administration to nonsinging adult female canaries induces song, making this a model for behavioral plasticity and its underlying neural mechanisms in vertebrates. The song control nucleus HVC is traditionally believed to undergo a substantial size change when transitioning from a nonfunctional to a functional (song-producing) state. Using 2-photon in vivo imaging, we tracked the spatial distribution and anatomical properties of HVC neurons over several weeks of testosterone-induced song development. Surprisingly, despite ultrastructural changes of HVC neurons, testosterone did neither alter neuronal spacing nor HVC size. Instead, spatial transcriptomics revealed that testosterone modulates gene networks throughout HVC, aligning transcriptomic profiles between its peripheral and central HVC regions in singing birds, thereby mimicking the histological appearance of an enlarging HVC. Our results demonstrate that changes in HVC size in adults reflect phenotypic changes in neurons within a stable framework. Importantly, the nonfunctional state is not associated with a reduced brain area volume, preserving HVC's capacity for functional differentiation throughout life.

Pollinator declines globally threaten ecosystem stability and agricultural productivity. Reconstructing pollinator historic demographies provides an evolutionary perspective to understand contemporary population declines. The Franklin bumble bee (Bombus franklini), once endemic to Oregon and California and last observed alive in 2006, is emblematic of this phenomenon. We collected whole-genome sequence data from museum specimens spanning four decades to elucidate the genetic and demographic history of this potentially extinct species. Heterozygosity estimates of 25 individuals were remarkably low, and runs of homozygosity (ROH) patterns identified short segments suggestive of historical inbreeding, with some individuals having almost entire chromosomes in ROH. Demographic reconstructions revealed a marked decline in effective population size beginning in the late Pleistocene, with further declines in the last 400 y, which may have been influenced by fire and drought stressors. We found little to no genomic evidence implicating pathogens in the species' decline and used coalescent simulations to show that we would be able to detect recently reduced heterozygosity only when colony-level survival rates are 15 to 30%. We conclude that a combination of historically low effective population size and genetic diversity along with environmental stochasticity heightened this species' extinction vulnerability prior to recent anthropogenic stressors. This study demonstrates the utility of museum collections for clarifying genetic and demographic dynamics of rare species and suggests that B. franklini may have already been on a trajectory of decline prior to human impacts.

Simultaneous measurements of HDO, H218O, and H216O in water evolved during pyrolysis of powdered rock samples acquired by the Curiosity rover within Gale crater's clay-bearing units indicate extreme and variable heavy-isotope enrichments averaging ~4.5 times the D/H ratio and ~1.03 times the 18O/16O ratio of terrestrial seawater. These enrichments are recorded in water desorbed from mineral surfaces and evolved from poorly crystalline phases, hydrated salts, jarosite, and clays. All evolved waters are deuterium-enriched relative to common terrestrial waters, reflecting hydrogen loss to space. Because oxygen in structurally bound hydroxyl groups is least likely to exchange with other sources over geologic timescales, we focus on oxygen in water evolved during dehydroxylation of smectite clays. Several samples have 18O/16O ratios commensurate with precipitation from, or near-complete equilibration with, water moderately 18O-enriched relative to terrestrial meteoric waters-consistent with other evidence that Mars's hydrosphere is basically like Earth's in terms of oxygen isotopes. Unlike hydrogen, oxygen atmospheric escape did not lead to extreme 18O enrichments on Mars. Locally, however, most Gale smectites' 18O/16O values require a pronounced 18O-enrichment of their parental waters. On Earth, the most extreme 18O enrichments in surface waters are found in closed basins having undergone significant evaporative loss into a low-humidity atmosphere, and the 18O/16O of authigenic clay minerals formed in these environs reflect those enrichments. A similar process acting on the hydrologic reservoir local to Gale at the time of clay formation and early diagenesis is a plausible explanation for the distinctive oxygen isotopic compositions of these clays.

Rice (Oryza sativa) was first domesticated beginning ~9,000 y ago in China as the japonica variety group/subspecies. Using genomic data from 456 japonica landraces, including data for 47 herbarium specimens collected over the last 167 y, we reconstruct how japonica rice moved from its center of origin to other parts of Asia beginning ~4,000 to 5,500 y ago. We observe an enrichment of pathogen resistance loci in selective sweeps associated with distinct geographic populations, suggesting that biotic interactions may be a key driver of local adaptation. We also find that the majority of 76 known functional mutations present in our japonica landraces-many of them associated with japonica rice domestication and diversification and important for modern breeding-had their origins in the Pleistocene >11,700 y ago and increased in allele frequency during key events in the evolution of rice.

Although seminal studies from the early 1960s suggested quality preschool can have lasting positive effects, agreement is lacking on the efficacy of different preschool models. The Montessori model is longstanding but lacks rigorous impact studies; prior random lottery studies included just one or two schools, among other compromises. Here, we report on end-of-kindergarten (age 5 to 6) impacts from a national study of public Montessori preschool. We compared children offered a Montessori seat via competitive lottery admission processes at one of 24 public Montessori schools at age 3 ([Formula: see text]) to children not offered a seat ([Formula: see text]), estimating Montessori impacts with intention-to-treat and complier average causal effect models. Roughly half of the treatment sample still attended Montessori for kindergarten. Although there were no notable impacts at the end of PK3 or PK4, at the end of kindergarten, controlling for baseline scores and demographics, Montessori children had significantly higher reading, short-term memory, theory of mind, and executive function scores. Intention-to-treat effect sizes exceeded a fifth of a SD, considered large in field-based school research [M. A. Kraft, Educ. Res. 49, 241-253 (2020)]. This contrasts sharply with the more typical finding, where impacts of preschool are observed immediately following the program but disappear by the end of kindergarten. Further, a cost analysis suggested three years of public Montessori preschool costs less per child than traditional programs, largely due to Montessori having higher child:teacher ratios in PK3 and PK4. Although sensitivity and robustness analyses yielded similar results, important limitations of the study should be noted.