Slide-tags enables single-nucleus barcoding for multimodal spatial genomics.

Recent technological innovations have enabled the high-throughput quantification of gene expression and epigenetic regulation within individual cells, transforming our understanding of how complex tissues are constructed1-6. However, missing from these measurements is the ability to routinely and easily spatially localize these profiled cells. We developed a strategy, Slide-tags, in which single nuclei within an intact tissue section are tagged with spatial barcode oligonucleotides derived from DNA-barcoded beads with known positions. These tagged nuclei can then be used as an input into a wide variety of single-nucleus profiling assays. Application of Slide-tags to the mouse hippocampus positioned nuclei at less than 10 µm spatial resolution and delivered whole-transcriptome data that are indistinguishable in quality from ordinary single-nucleus RNA-sequencing data. To demonstrate that Slide-tags can be applied to a wide variety of human tissues, we performed the assay on brain, tonsil and melanoma. We revealed cell-type-specific spatially varying gene expression across cortical layers and spatially contextualized receptor-ligand interactions driving B cell maturation in lymphoid tissue. A major benefit of Slide-tags is that it is easily adaptable to almost any single-cell measurement technology. As a proof of principle, we performed multiomic measurements of open chromatin, RNA and T cell receptor (TCR) sequences in the same cells from metastatic melanoma, identifying transcription factor motifs driving cancer cell state transitions in spatially distinct microenvironments. Slide-tags offers a universal platform for importing the compendium of established single-cell measurements into the spatial genomics repertoire.

Multimodal regulatory elements within a hormone-specific super enhancer control a heterogeneous transcriptional response.

The hormone-stimulated glucocorticoid receptor (GR) modulates transcription by interacting with thousands of enhancers and GR binding sites (GBSs) throughout the genome. Here, we examined the effects of GR binding on enhancer dynamics and investigated the contributions of individual GBSs to the hormone response. Hormone treatment resulted in genome-wide reorganization of the enhancer landscape in breast cancer cells. Upstream of the DDIT4 oncogene, GR bound to four sites constituting a hormone-dependent super enhancer. Three GBSs were required as hormone-dependent enhancers that differentially promoted histone acetylation, transcription frequency, and burst size. Conversely, the fourth site suppressed transcription and hormone treatment alleviated this suppression. GR binding within the super enhancer promoted a loop-switching mechanism that allowed interaction of the DDIT4 TSS with the active GBSs. The unique functions of each GR binding site contribute to hormone-induced transcriptional heterogeneity and demonstrate the potential for targeted modulation of oncogene expression.

Discrete measurements of RNA polymerase and reverse transcriptase fidelity reveal evolutionary tuning.

Direct methods for determining the fidelity of DNA polymerases are robust, with relatively little sample manipulation before sequencing. In contrast, methods for measuring RNA polymerase and reverse transcriptase fidelities are complicated by additional preparation steps that introduce ambiguity and error. Here, we describe a sequencing method, termed Roll-Seq, for simultaneously determining the individual fidelities of RNA polymerases and reverse transcriptases (RT) using Pacific Biosciences Single Molecule Real-Time sequencing. By employing reverse transcriptases with high rolling-circle activity, Roll-Seq generates long concatemeric cDNA from a circular RNA template. To discern the origin of a mutation, errors are recorded and determined to occur within a single concatemer (reverse transcriptase error) or all concatemers (RNA polymerase error) over the cDNA strand. We used Roll-Seq to measure the fidelities of T7 RNA polymerases, a Group II intron-encoded RT (Induro), and two LINE RTs (Fasciolopsis buski R2-RT and human LINE-1). Substitution rates for Induro and R2-RT are the same for cDNA and second strand synthesis while LINE-1 has 2.5-fold lower fidelity when performing second strand synthesis. Deletion and insertion rates increase for all RTs during second strand synthesis. In addition, we find that a structured RNA template impacts fidelity for both RNA polymerase and RT. The accuracy and precision of Roll-Seq enable this method to be applied as a complementary analysis to structural and mechanistic characterization of RNA polymerases and reverse transcriptases or as a screening method for RNAP and RT fidelity.

Within- and transgenerational stress legacy effects of ocean acidification on red abalone (Haliotis rufescens) growth and survival.

Understanding the mechanisms by which individual organisms respond and populations adapt to global climate change is a critical challenge. The role of plasticity and acclimation, within and across generations, may be essential given the pace of change. We investigated plasticity across generations and life stages in response to ocean acidification (OA), which poses a growing threat to both wild populations and the sustainable aquaculture of shellfish. Most studies of OA on shellfish focus on acute effects, and less is known regarding the longer term carryover effects that may manifest within or across generations. We assessed these longer term effects in red abalone (Haliotis rufescens) using a multi-generational split-brood experiment. We spawned adults raised in ambient conditions to create offspring that we then exposed to high pCO2 (1180 µatm; simulating OA) or low pCO2 (450 µatm; control or ambient conditions) during the first 3 months of life. We then allowed these animals to reach maturity in ambient common garden conditions for 4 years before returning the adults into high or low pCO2 treatments for 11 months and measuring growth and reproductive potential. Early-life exposure to OA in the F1 generation decreased adult growth rate even after 5 years especially when abalone were re-exposed to OA as adults. Adult but not early-life exposure to OA negatively impacted fecundity. We then exposed the F2 offspring to high or low pCO2 treatments for the first 3 months of life in a fully factorial, split-brood design. We found negative transgenerational effects of parental OA exposure on survival and growth of F2 offspring, in addition to significant direct effects of OA on F2 survival. These results show that the negative impacts of OA can last within and across generations, but that buffering against OA conditions at critical life-history windows can mitigate these effects.

One-device colonoscopy: feasibility, cost savings, and plastic waste reduction by procedure indication, when performed by a high detecting colonoscopist.

BACKGROUND: Cold forceps and snares are each effective for removing polyps of 1-3 mm, while snares are more effective for polyps of 4-10 mm in size. If, in the same patient, polyps of 1-3 mm are removed with forceps and those of 4-10 mm with snares, two devices are used. If cold snares are used to resect all lesions of 1-10 mm (one-device colonoscopy), there is a potential for lower costs and less plastic waste. METHODS: A single high detecting colonoscopist prospectively measured the feasibility of cold snaring all colorectal lesions of ≤10 mm in size, along with the associated costs and plastic waste reduction. RESULTS: 677 consecutive lower gastrointestinal endoscopies (not for inflammatory bowel disease) were assessed. Of 1430 lesions of 1-3 mm and 1685 lesions of 4-10 mm in size, 1428 (99.9%, 95%CI 99.5%-100%) and 1674 (99.3%, 95%CI 98.8%-99.7%), respectively, were successfully resected using cold snaring. Among 379 screening and surveillance patients, universal cold snaring of lesions ≤10 mm saved 35 and 47 cold forceps per 100 screening and surveillance patients, respectively. CONCLUSION: Cold snare resection of all lesions ≤10 mm (one-device colonoscopy) was feasible, and reduced costs and plastic waste.

How modularity and heterotrophy complicate the understanding of the causes of thermal performance curves: the case of feeding rate in a filter-feeding animal.

Warming global temperatures have consequences for biological rates. Feeding rates reflect the intake of energy that fuels survival, growth and reproduction. However, temperature can also affect food abundance and quality, as well as feeding behavior, which all affect feeding rate, making it challenging to understand the pathways by which temperature affects the intake of energy. Therefore, we experimentally assessed how clearance rate varied across a thermal gradient in a filter-feeding colonial marine invertebrate (the bryozoan Bugula neritina). We also assessed how temperature affects phytoplankton as a food source, and zooid states within a colony that affect energy budgets and feeding behavior. Clearance rate increased linearly from 18°C to 32°C, a temperature range that the population experiences most of the year. However, temperature increased algal cell size, and decreased the proportion of feeding zooids, suggesting indirect effects of temperature on clearance rates. Temperature increased polypide regression, possibly as a stress response because satiation occurred quicker, or because phytoplankton quality declined. Temperature had a greater effect on clearance rate per feeding zooid than it did per total zooids. Together, these results suggest that the effect of temperature on clearance rate at the colony level is not just the outcome of individual zooids feeding more in direct response to temperature but also emerges from temperature increasing polypide regression and the remaining zooids increasing their feeding rates in response. Our study highlights some of the challenges for understanding why temperature affects feeding rates, especially for understudied, yet ecologically important, marine colonial organisms.

Cryo-EM structure of the insect olfactory receptor Orco.

The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a family of odorant-gated ion channels comprised of a highly conserved co-receptor (Orco) and a divergent odorant receptor (OR) that confers chemical specificity. Here, we present the single-particle cryo-electron microscopy structure of an Orco homomer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution, providing structural insight into this receptor family. Orco possesses a novel channel architecture, with four subunits symmetrically arranged around a central pore that diverges into four lateral conduits that open to the cytosol. The Orco tetramer has few inter-subunit interactions within the membrane and is bound together by a small cytoplasmic anchor domain. The minimal sequence conservation among ORs maps largely to the pore and anchor domain, shedding light on how the architecture of this receptor family accommodates its remarkable sequence diversity and facilitates the evolution of odour tuning.

Serum Proteomic Signatures of Common Health Outcomes among Older Adults.

INTRODUCTION: In aging populations, the coexistence of multiple health comorbidities represents a significant challenge for clinicians and researchers. Leveraging advances in omics techniques to characterize these health conditions may provide insight into disease pathogenesis as well as reveal biomarkers for monitoring, prognostication, and diagnosis. Researchers have previously established the utility of big data approaches with respect to comprehensive health outcome measurements in younger populations, identifying protein markers that may provide significant health information with a single blood sample. METHODS: Here, we employed a similar approach in two cohorts of older adults, the Baltimore Longitudinal Study of Aging (mean age = 76.12 years) and InCHIANTI Study (mean age = 66.05 years), examining the relationship between levels of serum proteins and 5 key health outcomes: kidney function, fasting glucose, physical activity, lean body mass, and percent body fat. RESULTS: Correlations between proteins and health outcomes were primarily shared across both older adult cohorts. We further identified that most proteins associated with health outcomes in the older adult cohorts were not associated with the same outcomes in a prior study of a younger population. A subset of proteins, adiponectin, MIC-1, and NCAM-120, were associated with at least three health outcomes in both older adult cohorts but not in the previously published younger cohort, suggesting that they may represent plausible markers of general health in older adult populations. CONCLUSION: Taken together, these findings suggest that comprehensive protein health markers have utility in aging populations and are distinct from those identified in younger adults, indicating unique mechanisms of disease with aging.

Dynactin 1 negatively regulates HIV-1 infection by sequestering the host cofactor CLIP170.

Many viruses directly engage and require the dynein-dynactin motor-adaptor complex in order to transport along microtubules (MTs) to the nucleus and initiate infection. HIV type 1 (HIV-1) exploits dynein, the dynein adaptor BICD2, and core dynactin subunits but unlike several other viruses, does not require dynactin-1 (DCTN1). The underlying reason for HIV-1's variant dynein engagement strategy and independence from DCTN1 remains unknown. Here, we reveal that DCTN1 actually inhibits early HIV-1 infection by interfering with the ability of viral cores to interact with critical host cofactors. Specifically, DCTN1 competes for binding to HIV-1 particles with cytoplasmic linker protein 170 (CLIP170), one of several MT plus-end tracking proteins (+TIPs) that regulate the stability of viral cores after entry into the cell. Outside of its function as a dynactin subunit, DCTN1 also functions as a +TIP that we find sequesters CLIP170 from incoming particles. Deletion of the Zinc knuckle (Zn) domain in CLIP170 that mediates its interactions with several proteins, including DCTN1, increased CLIP170 binding to virus particles but failed to promote infection, further suggesting that DCTN1 blocks a critical proviral function of CLIP170 mediated by its Zn domain. Our findings suggest that the unique manner in which HIV-1 binds and exploits +TIPs to regulate particle stability leaves them vulnerable to the negative effects of DCTN1 on +TIP availability and function, which may in turn have driven HIV-1 to evolve away from DCTN1 in favor of BICD2-based engagement of dynein during early infection.

Hedgehog and Platelet-derived Growth Factor Signaling Intersect during Postnatal Lung Development.

Normal lung development critically depends on HH (Hedgehog) and PDGF (platelet-derived growth factor) signaling, which coordinate mesenchymal differentiation and proliferation. PDGF signaling is required for postnatal alveolar septum formation by myofibroblasts. Recently, we demonstrated a requirement for HH in postnatal lung development involving alveolar myofibroblast differentiation. Given shared features of HH signaling and PDGF signaling and their impact on this key cell type, we sought to clarify their relationship during murine postnatal lung development. Timed experiments revealed that HH inhibition phenocopies the key lung myofibroblast phenotypes of Pdgfa (platelet-derived growth factor subunit A) and Pdgfra (platelet-derived growth factor receptor alpha) knockouts during secondary alveolar septation. Using a dual signaling reporter, Gli1lZ;PdgfraEGFP, we show that HH and PDGF pathway intermediates are concurrently expressed during alveolar septal myofibroblast accumulation, suggesting pathway convergence in the generation of lung myofibroblasts. Consistent with this hypothesis, HH inhibition reduces Pdgfra expression and diminishes the number of Pdgfra-positive and Pdgfra-lineage cells in postnatal lungs. Bulk RNA sequencing data of Pdgfra-expressing cells from Postnatal Day 8 (P8) lungs show that HH inhibition alters the expression not only of well-established HH targets but also of several putative PDGF target genes. This, together with the presence of Gli-binding sites in PDGF target genes, suggests HH input into PDGF signaling. We identified these HH/PDGF targets in several postnatal lung mesenchymal cell populations, including myofibroblasts, using single-cell transcriptomic analysis. Collectively, our data indicate that HH signaling and PDGF signaling intersect to support myofibroblast/fibroblast function during secondary alveolar septum formation. Moreover, they provide a molecular foundation relevant to perinatal lung diseases associated with impaired alveolarization.

Experimental and computational studies of sulfided NiMo supported on pillared clay: catalyst activation and guaiacol adsorption sites.

We report on intermediate (oxysulfides) and sulfided structures of NiMo supported on aluminium pillared clay (Al-PILC) during the catalyst activation process and the prefered guaiacol adsorption sites on the sulfided catalyst. In situ X-ray absorption fine structure (XAFS) together with density functional theory (DFT) calculations confirm the existence of ill-defined suboxides (MoOx, NiOx) and the well-known subsulfides (Mo2S9, Ni3S2) at the first stage which, at a later stage in the process, transform into MoS2 with two edges, oxygen-decorated Mo and Ni with zero sulfur coverage. The freshly sulfided NiMoS2 catalyst under sulfiding agents is mainly terminated by Mo-edge surface with 50% sulfur coverage (Mo-S50) with a disordered Ni-edge surface that can be assigned as NiMoS (1̄010). When exposed to an inert atmosphere such as He gas, the Mo and Ni edges evolved partially into new structures of Mo and Ni edges with zero sulfur coverage, labelled as Mo-Bare and Ni-Bare. Guaiacol is often used as a model compound for lignin and a series of calculations of guaiacol on the structural edges of a sulfided NiMoS2 catalyst show relatively good agreement between the observed and calculated inelastic neutron scattering (INS) spectra for Mo-S50, Ni-Bare, and NiMoS (1̄010) where guaiacol weakly chemisorbed via oxygen atom of OH group. The results also confirm that guaiacol is physisorbed on the basal plane of NiMoS2 in a horizontal (flat-lying) configuration via van der Waals interaction at a separation of about 3.25 Å.

The longitudinal interplay between insecure attachment behaviors and psychosocial strengths among children in child welfare services.

Children who have experienced maltreatment are more likely to have disrupted attachments, fewer psychosocial strengths, and poorer long-term psychosocial outcomes. However, few studies have examined the interplay between attachment security and psychosocial strengths among children involved in therapeutic services in the context of the child welfare system. The present longitudinal study examines the insecure attachment behaviors and psychosocial strengths of 555 children referred to the Therapeutic Family Care program (TFCP) in Cobourg, Ontario between 2000 and 2019. The children were assessed by their caregivers on a regular basis using the Assessment Checklist for Children (ACC) and the complementary strengths-focused ACC+ measure. Average age of children at baseline was 9.57 years (SD = 3.51) and 229 (41.26%) were female. We conducted growth curve and random intercepts cross-lagged panel models to test the longitudinal interplay between insecure attachment behaviors and strengths. Results suggest that females' attachment security improved, males' attachment security worsened, and both males and females developed strengths over time. Further, analyses revealed a directional effect, whereby fewer insecure attachment behaviors predicted more psychosocial strengths approximately 6 months later. Implications for attachment-oriented and strengths-based services in the context of child welfare are discussed.

Modeling between-population variation in COVID-19 dynamics in Hubei, Lombardy, and New York City.

As the COVID-19 pandemic continues, formulating targeted policy interventions that are informed by differential severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission dynamics will be of vital importance to national and regional governments. We develop an individual-level model for SARS-CoV-2 transmission that accounts for location-dependent distributions of age, household structure, and comorbidities. We use these distributions together with age-stratified contact matrices to instantiate specific models for Hubei, China; Lombardy, Italy; and New York City, United States. Using data on reported deaths to obtain a posterior distribution over unknown parameters, we infer differences in the progression of the epidemic in the three locations. We also examine the role of transmission due to particular age groups on total infections and deaths. The effect of limiting contacts by a particular age group varies by location, indicating that strategies to reduce transmission should be tailored based on population-specific demography and social structure. These findings highlight the role of between-population variation in formulating policy interventions. Across the three populations, though, we find that targeted "salutary sheltering" by 50% of a single age group may substantially curtail transmission when combined with the adoption of physical distancing measures by the rest of the population.

Deviant peer affiliation mediates the prospective association from impulsivity to alcohol use in late adolescence.

INTRODUCTION: Previous research has found that impulsivity and deviant peer affiliation predict alcohol use among adolescents. However, it remains unclear to what extent these risk factors predict alcohol use in conjunction with one another, and to what extent they predict over and above correlated risk factors, such as pre-existing externalizing problems and sociodemographic characteristics. The present study tested the hypothesis that deviant peer affiliation would mediate the prospective association between impulsivity and alcohol use in adolescence (ages 13-18 years), controlling for a wide range of family and child-level covariates. METHODS: Analyses were conducted using data from 2318 participants from the Longitudinal Cohort Study of the Project on Human Development in Chicago Neighborhoods. Participants were approximately 9, 12, or 15 years of age at wave 1 of the study, with waves 2 and 3 taking place at approximately 2-year intervals. The sample composition was 50.3% male, 46.1% Hispanic, 35.6% Black, non-Hispanic, 14.4% White, non-Hispanic, and 3.9% other race/ethnicity. RESULTS: Results from path analyses indicated that the prospective association between impulsivity and alcohol use was mediated by peer deviance, but only for the oldest (age 15) cohort. CONCLUSIONS: Findings from the present study suggest that despite impulsivity being a dispositional characteristic, its effects on alcohol use in later adolescence are achieved through a social pathway, via affiliation with deviant peers. It further suggests that this pathway, especially the link from impulsivity to affiliation with deviant peers, may not operate until late adolescence. Findings suggest that alcohol use may be prevented or reduced among impulsive adolescents by reducing their exposure to delinquent peers.

Increased stroke severity and mortality in patients with SARS-CoV-2 infection: An analysis from the N3C database.

BACKGROUND: Studies from early in the COVID-19 pandemic showed that patients with ischemic stroke and concurrent SARS-CoV-2 infection had increased stroke severity. We aimed to test the hypothesis that this association persisted throughout the first year of the pandemic and that a similar increase in stroke severity was present in patients with hemorrhagic stroke. METHODS: Using the National Institute of Health National COVID Cohort Collaborative (N3C) database, we identified a cohort of patients with stroke hospitalized in the United States between March 1, 2020 and February 28, 2021. We propensity score matched patients with concurrent stroke and SARS-COV-2 infection and available NIH Stroke Scale (NIHSS) scores to all other patients with stroke in a 1:3 ratio. Nearest neighbor matching with a caliper of 0.25 was used for most factors and exact matching was used for race/ethnicity and site. We modeled stroke severity as measured by admission NIHSS and the outcomes of death and length of stay. We also explored the temporal relationship between time of SARS-COV-2 diagnosis and incidence of stroke. RESULTS: Our query identified 43,295 patients hospitalized with ischemic stroke (5765 with SARS-COV-2, 37,530 without) and 18,107 patients hospitalized with hemorrhagic stroke (2114 with SARS-COV-2, 15,993 without). Analysis of our propensity matched cohort revealed that stroke patients with concurrent SARS-COV-2 had increased NIHSS (Ischemic stroke: IRR=1.43, 95% CI:1.33-1.52, p<0.001; hemorrhagic stroke: IRR=1.20, 95% CI:1.08-1.33, p<0.001), length of stay (Ischemic stroke: estimate = 1.48, 95% CI: 1.37, 1.61, p<0.001; hemorrhagic stroke: estimate = 1.25, 95% CI: 1.06, 1.47, p=0.007) and higher odds of death (Ischemic stroke: OR 2.19, 95% CI: 1.79-2.68, p<0.001; hemorrhagic stroke: OR 2.19, 95% CI: 1.79-2.68, p<0.001). We observed the highest incidence of stroke diagnosis on the same day as SARS-COV-2 diagnosis with a logarithmic decline in counts. CONCLUSION: This retrospective observational analysis suggests that stroke severity in patients with concurrent SARS-COV-2 was increased throughout the first year of the pandemic.

Legionella pneumophila Cas2 Promotes the Expression of Small Heat Shock Protein C2 That Is Required for Thermal Tolerance and Optimal Intracellular Infection.

Previously, we demonstrated that Cas2 encoded within the CRISPR-Cas locus of Legionella pneumophila strain 130b promotes the ability of the Legionella pathogen to infect amoebal hosts. Given that L. pneumophila Cas2 has RNase activity, we posited that the cytoplasmic protein is regulating the expression of another Legionella gene(s) that fosters intracellular infection. Proteomics revealed 10 proteins at diminished levels in the cas2 mutant, and reverse transcription-quantitative (qRT-PCR) confirmed the reduced expression of a gene encoding putative small heat shock protein C2 (HspC2), among several others. As predicted, the gene was expressed more highly at 37°C to 50°C than that at 30°C, and an hspC2 mutant, but not its complemented derivative, displayed ~100-fold reduced CFU following heat shock at 55°C. Compatible with the effect of Cas2 on hspC2 expression, strains lacking Cas2 also had impaired thermal tolerance. The hspC2 mutant, like the cas2 mutant before it, was greatly impaired for infection of Acanthamoeba castellanii, a frequent host for legionellae in waters. HspC2 and Cas2 were not required for entry into these host cells but promoted the replicative phase of intracellular infection. Finally, the hspC2 mutant exhibited an additional defect during the infection of macrophages, which are the primary host for legionellae during lung infection. In summary, hspC2 is upregulated by the presence of Cas2, and HspC2 uniquely promotes both L. pneumophila extracellular survival at high temperatures and infection of amoebal and human host cells. To our knowledge, these findings also represent the first genetic proof linking Cas2 to thermotolerance, expanding the repertoire of noncanonical functions associated with CRISPR-Cas proteins.

Mechanisms of energy dissipation and relationship with tissue composition in human meniscus.

OBJECTIVE: The human meniscus is essential in maintaining proper knee joint function. The meniscus absorbs shock, distributes loads, and stabilizes the knee joint to prevent the onset of osteoarthritis. The extent of its shock-absorbing role can be estimated by measuring the energy dissipated by the meniscus during cyclic mechanical loading. METHODS: Samples were prepared from the central and horn regions of medial and lateral human menisci from 8 donors (both knees for total of 16 samples). Cyclic compression tests at several compression strains and frequencies yielded the energy dissipated per tissue volume. A GEE regression model was used to investigate the effects of compression, meniscal side and region, and water content on energy dissipation in order to account for repeated measures within samples. RESULTS: Energy dissipation by the meniscus increased with compressive strain from ∼0.1 kJ/m3 (at 10% strain) to ∼10 kJ/m3 (at 20% strain) and decreased with loading frequency. Samples from the anterior region provided the largest energy dissipation when compared to central and posterior samples (P < 0.05). Water content for the 16 meniscal tissues was 77.9 (C.I. 72.0-83.8%) of the total tissue mass. A negative correlation was found between energy dissipation and water content (P < 0.05). CONCLUSION: The extent of energy dissipated by the meniscus is inversely related to loading frequency and meniscal water content.

Couple Communication Behaviors During Sexual and Nonsexual Discussions and Their Association with Relationship Satisfaction.

The quality of communication between romantic partners has consistently been found to be associated with relationship well-being and stability. Studies on sexual and nonsexual communication, however, have typically assessed communication skills and behaviors using self-report measures. The use of observational methods has several advantages, including the ability to capture and allow for the independent coding of both partners' communication behaviors. With few exceptions, research applying observational methods has not distinguished between sexual and nonsexual communication behaviors. In the present study, we asked 126 young, mixed-sex couples to engage in sexual and nonsexual conflict discussions. The two 7-min discussions were videotaped and rated by trained coders on nine behavioral dimensions using an adaptation of the specific affect coding system (Gottman & Krokoff, 1989) and the system for coding interactions and family functioning (Lindahl & Malik, 2001). Coder ratings applied to the discussion as a whole. Analyses included factor analysis on the behavioral dimensions and multilevel modeling incorporating the actor-partner interdependence model (APIM). We found significant differences in how couples interacted during the two discussions, with more positive (affectionate and validating) and less negative behaviors during sexual discussions as compared to nonsexual discussions. In both women and men, expressions of positivity during the two types of conflict discussions were associated with higher relationship satisfaction. Gender differences were found in the association between negative behaviors during sexual discussions and relationship satisfaction, with men but not women's negative behaviors being associated with lower relationship satisfaction. These findings point at distinct qualities of sexual communication and its association with couples' relational well-being and contribute to a better scientific understanding, with clinical relevance, of sexual and nonsexual communication.

Recent total syntheses of anthraquinone-based natural products.

The scientific community has found deep interest in anthraquinone-based compounds due to their therapeutic properties and challenging structural elements. Various architecturally beautiful natural products have been successfully synthesized in recent decades utilizing two main strategies: either an early-stage synthesis of the anthraquinone and further elongation of the system, or a late-stage introduction of the anthraquinone ring moiety. Select syntheses of complex anthraquinone monomers and dimers within the past 20 years are described with an emphasis on the retrosynthetic disconnections that shape the anthraquinone-installation strategy.