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•Monomers are made inside of cells and exported to the wall by unknown mechanism(s).•Possible mechanisms include transporters such as ATP-binding cassette transporters.•Diffusion of ...monomers through membranes, driven by polymer formation, is possible.•In gymnosperms, monolignol glucosides represent a possible alternate route to lignin.•Cells can export lignin monomers into the shared walls of neighboring cells.
Lignin is a highly abundant polymer in plant cell walls that is essential for land plants’ ability to stand upright and transport water. Inside plant cells, lignin monomers, called monolignols, are made from phenylalanine via a multistep pathway. In the cell wall, monomers move freely, until they encounter stationary oxidative enzymes that determine where the lignin polymer forms. However, it remains unclear how lignin monomers are trafficked from inside the cell to the cell wall. Although multiple lines of circumstantial evidence implicate transporters, additional possible mechanisms include the diffusion of monomers across lipid bilayers and the release of monolignol glucosides stored in vacuoles. There are therefore potentially diverse and overlapping mechanisms of monolignol export.
The heart develops from 2 sources of mesoderm progenitors, the first and second heart field (FHF and SHF). Using a single-cell transcriptomic assay combined with genetic lineage tracing and live ...imaging, we find the FHF and SHF are subdivided into distinct pools of progenitors in gastrulating mouse embryos at earlier stages than previously thought. Each subpopulation has a distinct origin in the primitive streak. The first progenitors to leave the primitive streak contribute to the left ventricle, shortly after right ventricle progenitor emigrate, followed by the outflow tract and atrial progenitors. Moreover, a subset of atrial progenitors are gradually incorporated in posterior locations of the FHF. Although cells allocated to the outflow tract and atrium leave the primitive streak at a similar stage, they arise from different regions. Outflow tract cells originate from distal locations in the primitive streak while atrial progenitors are positioned more proximally. Moreover, single-cell RNA sequencing demonstrates that the primitive streak cells contributing to the ventricles have a distinct molecular signature from those forming the outflow tract and atrium. We conclude that cardiac progenitors are prepatterned within the primitive streak and this prefigures their allocation to distinct anatomical structures of the heart. Together, our data provide a new molecular and spatial map of mammalian cardiac progenitors that will support future studies of heart development, function, and disease.
Microbial and viral communities transform the chemistry of Earth's ecosystems, yet the specific reactions catalyzed by these biological engines are hard to decode due to the absence of a scalable, ...metabolically resolved, annotation software. Here, we present DRAM (Distilled and Refined Annotation of Metabolism), a framework to translate the deluge of microbiome-based genomic information into a catalog of microbial traits. To demonstrate the applicability of DRAM across metabolically diverse genomes, we evaluated DRAM performance on a defined, in silico soil community and previously published human gut metagenomes. We show that DRAM accurately assigned microbial contributions to geochemical cycles and automated the partitioning of gut microbial carbohydrate metabolism at substrate levels. DRAM-v, the viral mode of DRAM, established rules to identify virally-encoded auxiliary metabolic genes (AMGs), resulting in the metabolic categorization of thousands of putative AMGs from soils and guts. Together DRAM and DRAM-v provide critical metabolic profiling capabilities that decipher mechanisms underpinning microbiome function.
Pretend play has been claimed to be crucial to children's healthy development. Here we examine evidence for this position versus 2 alternatives: Pretend play is 1 of many routes to positive ...developments (equifinality), and pretend play is an epiphenomenon of other factors that drive development. Evidence from several domains is considered. For language, narrative, and emotion regulation, the research conducted to date is consistent with all 3 positions but insufficient to draw conclusions. For executive function and social skills, existing research leans against the crucial causal position but is insufficient to differentiate the other 2. For reasoning, equifinality is definitely supported, ruling out a crucially causal position but still leaving open the possibility that pretend play is epiphenomenal. For problem solving, there is no compelling evidence that pretend play helps or is even a correlate. For creativity, intelligence, conservation, and theory of mind, inconsistent correlational results from sound studies and nonreplication with masked experimenters are problematic for a causal position, and some good studies favor an epiphenomenon position in which child, adult, and environment characteristics that go along with play are the true causal agents. We end by considering epiphenomenalism more deeply and discussing implications for preschool settings and further research in this domain. Our take-away message is that existing evidence does not support strong causal claims about the unique importance of pretend play for development and that much more and better research is essential for clarifying its possible role. (Contains 12 tables and 10 footnotes.)
The current paradigm, widely incorporated in soil biogeochemical models, is that microbial methanogenesis can only occur in anoxic habitats. In contrast, here we show clear geochemical and biological ...evidence for methane production in well-oxygenated soils of a freshwater wetland. A comparison of oxic to anoxic soils reveal up to ten times greater methane production and nine times more methanogenesis activity in oxygenated soils. Metagenomic and metatranscriptomic sequencing recover the first near-complete genomes for a novel methanogen species, and show acetoclastic production from this organism was the dominant methanogenesis pathway in oxygenated soils. This organism, Candidatus Methanothrix paradoxum, is prevalent across methane emitting ecosystems, suggesting a global significance. Moreover, in this wetland, we estimate that up to 80% of methane fluxes could be attributed to methanogenesis in oxygenated soils. Together, our findings challenge a widely held assumption about methanogenesis, with significant ramifications for global methane estimates and Earth system modeling.
The gut microbiota influences both local and systemic inflammation. Inflammation contributes to development, progression, and treatment of cancer, but it remains unclear whether commensal bacteria ...affect inflammation in the sterile tumor microenvironment. Here, we show that disruption of the microbiota impairs the response of subcutaneous tumors to CpG-oligonucleotide immunotherapy and platinum chemotherapy. In antibiotics-treated or germ-free mice, tumor-infiltrating myeloid-derived cells responded poorly to therapy, resulting in lower cytokine production and tumor necrosis after CpG-oligonucleotide treatment and deficient production of reactive oxygen species and cytotoxicity after chemotherapy. Thus, optimal responses to cancer therapy require an intact commensal microbiota that mediates its effects by modulating myeloid-derived cell functions in the tumor microenvironment. These findings underscore the importance of the microbiota in the outcome of disease treatment.
Persistent human papillomavirus infection is associated with squamous cell carcinoma of the anal canal (SCCA). With changing sexual behaviors, SCCA incidence and patient demographics may also have ...changed in recent years.
The Surveillance, Epidemiology, and End Results public-use data set from 1973 to 2009 was analyzed to determine incidence trends for and demographic factors characterizing SCCA. Joinpoint analyses identified time points when incidence rates changed. For comparison, similar analyses were conducted for anal adenocarcinoma.
Joinpoint analyses identified 1997 as the single inflection point among 11,231 patients with SCCA, at which the slope of incidence rates statistically increased (1997 to 2009 v 1973 to 1996: risk ratio RR, 2.2; 95% CI, 2.1 to 2.3). Annual percent change (APC) increased for all SCCA stages and was the greatest for anal carcinoma in situ (CIS; APC, 14.2; 95% CI, 10.2 to 18.4). Demographic changes characterizing later versus earlier time period included younger age at diagnosis and rising incidence rates in all stage, sex, and racial groups. During 1997 to 2009, women were less likely to present with CIS (RR, 0.3; 95% CI, 0.3 to 0.3) but more likely to present with localized (RR, 1.2; 95% CI, 1.1 to 1.3) and regional SCCA (RR, 1.5; 95% CI, 1.4 to 1.7). In contrast, adenocarcinoma APCs among 1,791 patients remained stable during this time period.
CIS and SCCA incidence increased dramatically after 1997 for men and women, although men were more likely to be diagnosed with CIS. These changes likely resulted from available screening in men and argue for efforts to identify high-risk individuals who may benefit from screening.
Unusual photophysical properties of organic–inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge ...carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH3NH3PbI3) following photoexcitation, enabling an ultrafast probe of charge separation, hot‐carrier transport, and carrier–lattice coupling under 1‐sun‐equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band‐edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot‐carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz‐frequency lattice distortions, associated with reorganizations of the lead‐iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier–lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far‐above‐gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.
A burst of terahertz emission is observed from hybrid organic–inorganic perovskites, enabling an ultrafast probe of carrier separation and carrier–lattice coupling in these materials under 1‐sun illumination condition. Initial charge separation is shown to be driven by diffusion and not by surface fields or ferroelectricity. Finally, photogenerated carriers are found to drive coherent terahertz‐frequency lattice distortions at the femtosecond timescale.
The ability to exchange affective cues with others plays a key role in our ability to create and maintain meaningful social relationships. We express our emotions through a variety of socially ...salient cues, including facial expressions, the voice, and body movement. While significant advances have been made in our understanding of verbal and facial communication, to date, understanding of the role played by human body movement in our social interactions remains incomplete. To this end, here we describe the creation and validation of a new set of emotionally expressive whole-body dance movement stimuli, named the Motion Capture Norming (McNorm) Library, which was designed to reconcile a number of limitations associated with previous movement stimuli. This library comprises a series of point-light representations of a dancer’s movements, which were performed to communicate to observers neutrality, happiness, sadness, anger, and fear. Based on results from two validation experiments, participants could reliably discriminate the intended emotion expressed in the clips in this stimulus set, with accuracy rates up to 60% (chance = 20%). We further explored the impact of dance experience and trait empathy on emotion recognition and found that neither significantly impacted emotion discrimination. As all materials for presenting and analysing this movement library are openly available, we hope this resource will aid other researchers in further exploration of affective communication expressed by human bodily movement.
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