Beyond bulk: Density fractions explain heterogeneity in global soil carbon abundance and persistence.

Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of environmental factors on soil organic C partitioning among pools, abundance in each pool (mg C g-1  soil), and persistence (as approximated by radiocarbon abundance) in relatively unprotected particulate and protected mineral-bound pools. We show that C within particulate and mineral-associated pools consistently differed from one another in degree of persistence and relationship to environmental factors. Soil depth was the best predictor of C abundance and persistence, though it accounted for more variance in persistence. Persistence of all C pools decreased with increasing mean annual temperature (MAT) throughout the soil profile, whereas persistence increased with increasing wetness index (MAP/PET) in subsurface soils (30-176 cm). The relationship of C abundance (mg C g-1  soil) to climate varied among pools and with depth. Mineral-associated C in surface soils (<30 cm) increased more strongly with increasing wetness index than the free particulate C, but both pools showed attenuated responses to the wetness index at depth. Overall, these relationships suggest a strong influence of climate on soil C properties, and a potential loss of soil C from protected pools in areas with decreasing wetness. Relative persistence and abundance of C pools varied significantly among land cover types and soil parent material lithologies. This variability in each pool's relationship to environmental factors suggests that not all soil organic C is equally vulnerable to global change. Therefore, projections of future soil organic C based on patterns and responses of bulk soil organic C may be misleading.

Differential retention and divergent resolution of duplicate genes following whole-genome duplication.

The Paramecium aurelia complex is a group of 15 species that share at least three past whole-genome duplications (WGDs). The macronuclear genome sequences of P. biaurelia and P. sexaurelia are presented and compared to the published sequence of P. tetraurelia. Levels of duplicate-gene retention from the recent WGD differ by > 10% across species, with P. sexaurelia losing significantly more genes than P. biaurelia or P. tetraurelia. In addition, historically high rates of gene conversion have homogenized WGD paralogs, probably extending the paralogs' lifetimes. The probability of duplicate retention is positively correlated with GC content and expression level; ribosomal proteins, transcription factors, and intracellular signaling proteins are overrepresented among maintained duplicates. Finally, multiple sources of evidence indicate that P. sexaurelia diverged from the two other lineages immediately following, or perhaps concurrent with, the recent WGD, with approximately half of gene losses between P. tetraurelia and P. sexaurelia representing divergent gene resolutions (i.e., silencing of alternative paralogs), as expected for random duplicate loss between these species. Additionally, though P. biaurelia and P. tetraurelia diverged from each other much later, there are still more than 100 cases of divergent resolution between these two species. Taken together, these results indicate that divergent resolution of duplicate genes between lineages acts to reinforce reproductive isolation between species in the Paramecium aurelia complex.

A Single-Center Multidisciplinary Initiative to Reduce Catheter-Associated Urinary Tract Infection Rates: Quality and Financial Implications.

INTRODUCTION: Catheter-associated urinary tract infection (CAUTI) is an important patient safety issue that is responsible for an estimated 449334 annual infections, with an average direct cost of $790-$1200 per infection. In total, the cost associated with CAUTI is estimated to be $115 million to $1.82 billion annually. METHODS: We conducted an internal revenue analysis with a standard sensitivity analysis to assess the impact of a low-cost CAUTI reduction program on direct costs to the hospital over four years. The interventions included the formation of a multidisciplinary CAUTI reduction task force, formal data collection in all ICUs, staff education, and new electronic order sets with decision support. RESULTS: During the initial intervention period, the infection rate per 1000 catheter days decreased from 5.4 to 1.5. In the second year of the program, the infection rate increased to 4.6. After additional interventions were launched, infection rates decreased to 2.2. Cost savings per 1000 catheter days (±20%) during the initial intervention were $4501 ($3600-$5401). DISCUSSION: Our intervention demonstrated that provider education and electronic documentation prompts were followed by a significant decrease in catheter utilization, that in turn was followed by lower infection rates. Decreased emphasis on intervention goals were followed by an increase in CAUTI rates. Our subsequent interventions suggest that upward trends may be reversible.

Comparison of methods for mapping rhizosphere processes in the context of their surrounding root and soil environments.

The rhizosphere embodies a complex biogeochemical zone with enhanced rates of nutrient exchange between plants, soil, and microbial communities. Understanding controls on rhizosphere dynamics is critical to support emerging concepts including rhizosphere engineering and reduced dependence on chemical fertilizers which have direct application to food production, increased biofuel generation, and habitat restoration efforts. Yet, its fine spatial scale and complex interactions between geochemical and microbial processes within complex spatiotemporal gradients make the rhizosphere notoriously difficult to study. Emerging instrumentation and methodologies, however, are providing improved resolution to rhizosphere measurements and helping to address critical knowledge gaps in rhizosphere function, ecology, and establishment. Here, we examine recent advances in analysis techniques and the resulting potential for improved understanding of rhizosphere function.

Minimal effect of ectopic gene conversion among recent duplicates in four mammalian genomes.

Gene conversion between duplicated genes has been implicated in homogenization of gene families and reassortment of variation among paralogs. If conversion is common, this process could lead to errors in gene tree inference and subsequent overestimation of rates of gene duplication. After performing simulations to assess our power to detect gene conversion events, we determined rates of conversion among young, lineage-specific gene duplicates in four mammal species: human, rhesus macaque, mouse, and rat. Gene conversion rates (number of conversion events/number of gene pairs) among young duplicates range from 8.3% in macaque to 18.96% in rat, including a 5% false-positive rate. For all lineages, only 1-3% of the total amount of sequence examined was converted. There is no increase in GC content in conversion tracts compared to flanking regions of the same genes nor in conversion tracts compared to the same region in nonconverted gene-family members, suggesting that ectopic gene conversion does not significantly alter nucleotide composition in these duplicates. While the majority of gene duplicate pairs reside on different chromosomes in mammalian genomes, the majority of gene conversion events occur between duplicates on the same chromosome, even after controlling for divergence between duplicates. Among intrachromosomal duplicates, however, there is no correlation between the probability of conversion and physical distance between duplicates after controlling for divergence. Finally, we use a novel method to show that at most 5-10% of all gene trees involving young duplicates are likely to be incorrect due to gene conversion. We conclude that gene conversion has had only a small effect on mammalian genomes and gene duplicate evolution in general.

COVID-19 infections among HCWs exposed to a patient with a delayed diagnosis of COVID-19.

We report on COVID-19 risk among HCWs exposed to a patient diagnosed with COVID-19 on day 13 of hospitalization. There were 44 HCWs exposed to the patient before contact and droplet precautions were implemented: of these, 2 of 44 (5%) developed COVID-19 potentially attributable to the exposure.

Development of a Web-Based Nonoperative Small Bowel Obstruction Treatment Pathway App.

OBJECTIVE: An electronic pathway for the management of adhesive small bowel obstruction (SBO) was built and implemented on top of the electronic health record. The aims of this study are to describe the development of the electronic pathway and to report early outcomes. METHODS: The electronic SBO pathway was designed and implemented at a single institution. All patients admitted to a surgical service with a diagnosis of adhesive SBO were enrolled. Outcomes were compared across three time periods: (1) patients not placed on either pathway from September 2013 through December 2014, (2) patients enrolled in the paper pathway from January 2017 through January 2018, and (3) patients enrolled in the electronic pathway from March through October 2018. The electronic SBO pathway pulls real-time data from the electronic health record to prepopulate the evidence-based algorithm. Outcomes measured included length of stay (LOS), time to surgery, readmission, surgery, and need for bowel resection. Comparative analyses were completed with Pearson's chi-squared, analysis of variance, and Kruskal-Wallis tests. RESULTS: There were 46 patients enrolled in the electronic pathway compared with 93 patients on the paper pathway, and 101 nonpathway patients. Median LOS was lower in both pathway cohorts compared with those not on either pathway (3 days [range 1-11] vs. 3 days [range 1-27] vs. 4 days [range 1-13], p = 0.04). Rates of readmission, surgery, time to surgery, and bowel resection were not significantly different across the three groups. CONCLUSION: It is feasible to implement and utilize an electronic, evidence-based clinical pathway for adhesive SBOs. Use of the electronic and paper pathways was associated with decreased hospital LOS for patients with adhesive SBOs.

Evidence for genetic association of RORB with bipolar disorder.

BACKGROUND: Bipolar disorder, particularly in children, is characterized by rapid cycling and switching, making circadian clock genes plausible molecular underpinnings for bipolar disorder. We previously reported work establishing mice lacking the clock gene D-box binding protein (DBP) as a stress-reactive genetic animal model of bipolar disorder. Microarray studies revealed that expression of two closely related clock genes, RAR-related orphan receptors alpha (RORA) and beta (RORB), was altered in these mice. These retinoid-related receptors are involved in a number of pathways including neurogenesis, stress response, and modulation of circadian rhythms. Here we report association studies between bipolar disorder and single-nucleotide polymorphisms (SNPs) in RORA and RORB. METHODS: We genotyped 355 RORA and RORB SNPs in a pediatric cohort consisting of a family-based sample of 153 trios and an independent, non-overlapping case-control sample of 152 cases and 140 controls. Bipolar disorder in children and adolescents is characterized by increased stress reactivity and frequent episodes of shorter duration; thus our cohort provides a potentially enriched sample for identifying genes involved in cycling and switching. RESULTS: We report that four intronic RORB SNPs showed positive associations with the pediatric bipolar phenotype that survived Bonferroni correction for multiple comparisons in the case-control sample. Three RORB haplotype blocks implicating an additional 11 SNPs were also associated with the disease in the case-control sample. However, these significant associations were not replicated in the sample of trios. There was no evidence for association between pediatric bipolar disorder and any RORA SNPs or haplotype blocks after multiple-test correction. In addition, we found no strong evidence for association between the age-at-onset of bipolar disorder with any RORA or RORB SNPs. CONCLUSION: Our findings suggest that clock genes in general and RORB in particular may be important candidates for further investigation in the search for the molecular basis of bipolar disorder.