A second space age spanning omics, platforms and medicine across orbits.

The recent acceleration of commercial, private and multi-national spaceflight has created an unprecedented level of activity in low Earth orbit, concomitant with the largest-ever number of crewed missions entering space and preparations for exploration-class (lasting longer than one year) missions. Such rapid advancement into space from many new companies, countries and space-related entities has enabled a 'second space age'. This era is also poised to leverage, for the first time, modern tools and methods of molecular biology and precision medicine, thus enabling precision aerospace medicine for the crews. The applications of these biomedical technologies and algorithms are diverse, and encompass multi-omic, single-cell and spatial biology tools to investigate human and microbial responses to spaceflight. Additionally, they extend to the development of new imaging techniques, real-time cognitive assessments, physiological monitoring and personalized risk profiles tailored for astronauts. Furthermore, these technologies enable advancements in pharmacogenomics, as well as the identification of novel spaceflight biomarkers and the development of corresponding countermeasures. In this Perspective, we highlight some of the recent biomedical research from the National Aeronautics and Space Administration, Japan Aerospace Exploration Agency, European Space Agency and other space agencies, and detail the entrance of the commercial spaceflight sector (including SpaceX, Blue Origin, Axiom and Sierra Space) into aerospace medicine and space biology, the first aerospace medicine biobank, and various upcoming missions that will utilize these tools to ensure a permanent human presence beyond low Earth orbit, venturing out to other planets and moons.

Correction: Microbial phenotypic heterogeneity in response to a metabolic toxin: Continuous, dynamically shifting distribution of formaldehyde tolerance in Methylobacterium extorquens populations.

[This corrects the article DOI: 10.1371/journal.pgen.1008458.].

Rapid spectrophotometric detection for optimized production of landomycins and characterization of their therapeutic potential.

Microbial-derived natural products remain a major source of structurally diverse bioactive compounds and chemical scaffolds that have the potential as new therapeutics to target drug-resistant pathogens and cancers. In particular, genome mining has revealed the vast number of cryptic or low-yield biosynthetic gene clusters in the genus Streptomyces. However, low natural product yields-improvements to which have been hindered by the lack of high throughput methods-have slowed the discovery and development of many potential therapeutics. Here, we describe our efforts to improve yields of landomycins-angucycline family polyketides under investigation as cancer therapeutics-by a genetically modified Streptomyces cyanogenus 136. After simplifying the extraction process from S. cyanogenus cultures, we identified a wavelength at which the major landomycin products are absorbed in culture extracts, which we used to systematically explore culture medium compositions to improve total landomycin titers. Through correlational analysis, we simplified the culture optimization process by identifying an alternative wavelength at which culture supernatants absorb yet is representative of total landomycin titers. Using the subsequently improved sample throughput, we explored landomycin production during the culturing process to further increase landomycin yield and reduce culture time. Testing the antimicrobial activity of the isolated landomycins, we report broad inhibition of Gram-positive bacteria, inhibition of fungi by landomycinone, and broad landomycin resistance by Gram-negative bacteria that is likely mediated by the exclusion of landomycins by the bacterial membrane. Finally, the anticancer activity of the isolated landomycins against A549 lung carcinoma cells agrees with previous reports on other cell lines that glycan chain length correlates with activity. Given the prevalence of natural products produced by Streptomyces, as well as the light-absorbing moieties common to bioactive natural products and their metabolic precursors, our method is relevant to improving the yields of other natural products of interest.

EfgA is a conserved formaldehyde sensor that leads to bacterial growth arrest in response to elevated formaldehyde.

Normal cellular processes give rise to toxic metabolites that cells must mitigate. Formaldehyde is a universal stressor and potent metabolic toxin that is generated in organisms from bacteria to humans. Methylotrophic bacteria such as Methylorubrum extorquens face an acute challenge due to their production of formaldehyde as an obligate central intermediate of single-carbon metabolism. Mechanisms to sense and respond to formaldehyde were speculated to exist in methylotrophs for decades but had never been discovered. Here, we identify a member of the DUF336 domain family, named efgA for enhanced formaldehyde growth, that plays an important role in endogenous formaldehyde stress response in M. extorquens PA1 and is found almost exclusively in methylotrophic taxa. Our experimental analyses reveal that EfgA is a formaldehyde sensor that rapidly arrests growth in response to elevated levels of formaldehyde. Heterologous expression of EfgA in Escherichia coli increases formaldehyde resistance, indicating that its interaction partners are widespread and conserved. EfgA represents the first example of a formaldehyde stress response system that does not involve enzymatic detoxification. Thus, EfgA comprises a unique stress response mechanism in bacteria, whereby a single protein directly senses elevated levels of a toxic intracellular metabolite and safeguards cells from potential damage.

Guidance for Circumflex Scapular Artery Flap Utilization in Pediatric Reconstruction.

BACKGROUND: The circumflex scapular artery (CSA) flap system, consisting of scapular, parascapular, and chimeric flaps, is useful for pediatric reconstruction in many anatomical locations. The objectives of this case series are to offer insights into our decision-making process for selecting the CSA flap in particular pediatric reconstructive cases and to establish a framework for choosing a scapular or parascapular skin paddle. We also aim to emphasize important technical considerations of CSA flap utilization in pediatric patients. METHODS: Pediatric reconstruction with CSA flaps performed at our institution between 2006-2022 was retrospectively reviewed. Patient demographics, indications, flap characteristics, complications, and operative data were abstracted. Functional donor site morbidity was assessed through postoperative physical examinations. Unpaired t test analyzed scapular versus parascapular flap size. RESULTS: Eleven CSA flaps were successfully performed in 10 patients (6 scapular and 5 parascapular flaps). Patient ages ranged from 2 to 17 years. Scapular fasciocutaneous free flaps (n = 4) were performed in patients' ages 2-5 years for hand and forearm scar contractures. Two pedicled scapular flaps were performed for a single patient for bilateral axillary hidradenitis suppurativa. The 5 parascapular flaps were performed in patients' ages 2-14 years for calcaneus and forearm avulsion wounds and reconstruction after resection of hidradenitis suppurativa, nevus sebaceous, and Ewing sarcoma. In the sarcoma resection case, a chimeric flap with latissimus dorsi was employed. Average flap size was 101.6 ± 87.3 cm2 (range: 18-300 cm2). Parascapular flaps were significantly larger than scapular flaps (156.60 ± 105.84 cm2 vs 55.83 ± 26.97 cm2, P = 0.0495). Overall, 3 complications occurred (27.3% of cases) including venous congestion (n = 2) and wound dehiscence (n = 1). There were no reported cases of compromised shoulder function at 1.9 ± 2.5-year follow-up. The successful reconstruction rate for scapular, parascapular, and chimeric flaps was 100%. CONCLUSIONS: The CSA flap treated a wide variety of indications demonstrating the flap's attributes: large vessel caliber, wide arc of rotation, reliable vascular anatomy, minimal donor site morbidity, and ability to incorporate bone and muscle. Our cases also highlight important pediatric considerations such as vascular mismatch and limited scapular bone stock. We recommend selection of the parascapular over the scapular flap with reconstruction of larger, complex defects given its ability to be harvested with a large skin paddle.

A Review of Socioeconomic Disparities in Submucous Cleft Diagnosis and Outcomes.

Submucous cleft palate (SMCP) is a common congenital anomaly characterized by a diastasis of the levator veli palitini muscle. The subtlety of SMCP on physical examination can contribute to diagnostic delays. This study aims to analyze the factors contributing to delays in care and subsequent postoperative outcomes in patients with SMCP. All patients with surgical indications for SMCP who underwent palatoplasty at an urban academic children's hospital were included. Patient socioeconomic characteristics, medical history, and postoperative outcomes were collected. Patients were compared based on insurance type and government assistance utilization. Statistical analyses including independent t-test, Wilcoxon ranked sum test, χ2 analyses, Fisher's exact test, and stepwise logistic regression were performed. Among the 105 patients with SMCP, 69.5% (n=73) had public insurance and 30.5% (n=32) private. Patients with public insurance were diagnosed later (5.5±4.6 versus 2.6±2.4 years old; p<0.001) and underwent palatoplasty later (7.3±4.1 versus 4.4±3.4 years old; p<0.001) than those with private insurance. Patients receiving government assistance experienced higher rates of post-surgical persistent velopharyngeal insufficiency (74.5% versus 44.8%; p=0.006). The authors' results suggest a disparity in the recognition and treatment of surgical SMCP. Hence, financially vulnerable populations may experience an increased risk of inferior speech outcomes and subsequent therapies and procedures.

A Single Institution 19 Year Comparison of Furlow and Straight Line Palatoplasty Techniques in Bilateral Cleft Lip and Palate.

OBJECTIVE: This study aims to compare patients' speech correcting surgery and fistula rates between the Furlow and Straight Line (SLR) palatoplasty techniques when combined with greater palatine flaps for complete bilateral cleft lip and palate (BCLP) repair. DESIGN: This was a single-center IRB approved retrospective cohort study. SETTING: This study took place at an urban tertiary academic center. PATIENTS, PARTICIPANTS: All patients with BCLP anomalies that underwent repair between January 2003 and August 2022 were included. Patients with index operations at an outside institution or incomplete medical charting were excluded. INTERVENTIONS: A total of 1552 patients underwent palatoplasty during the study period. Of these, 192 (12.4%) met inclusion criteria with a diagnosis of BCLP. MAIN OUTCOME MEASURES: Primary outcomes of this study included rate of fistula and incidence of speech correcting surgery. Secondary outcomes included rate of surgical fistula repair. RESULTS: One hundred patients underwent SLR (52.1%) and 92 Furlow repair (47.9%). There was no significant difference in fistula rates between the SLR and Furlow repair cohorts (20.7% vs. 15.0%; p = 0.403). However, SLR was associated with lower rates of speech correcting surgery when compared to the Furlow repair (12.5% vs. 29.6%; p = 0.011). CONCLUSIONS: This study compares the effect of Furlow and SLR on speech outcomes and fistula rates in patients with BCLP. Our findings suggest that SLR resulted in an almost three times lower rate of velopharyngeal dysfunction requiring surgical intervention in patients with BCLP, while fistula rates remained similar.

The Forgotten Flap: The Pedicled Trapezius Flap's Utility in Pediatric Head and Neck Reconstruction-A Systematic Review.

BACKGROUND: When free tissue transfer is precluded or undesired, the pedicled trapezius flap is a viable alternative for adults requiring complex head and neck (H&N) defect reconstruction. However, the application of this flap in pediatric reconstruction is underexplored. This systematic review aimed to describe the use of the pedicled trapezius flap and investigate its efficacy in pediatric H&N reconstruction. METHODS: A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles describing the trapezius flap for H&N reconstruction in pediatric patients were included. Patient demographics, surgical indications, wound characteristics, flap characteristics, complications, and functional outcomes were abstracted. RESULTS: A systematic review identified 22 articles for inclusion. Studies mainly consisted of case reports (n = 11) and case series (n = 8). In total, 67 pedicled trapezius flaps were successfully performed for H&N reconstruction in 63 patients. The most common surgical indications included burn scar contractures (n = 46, 73.0%) and chronic wounds secondary to H&N masses (n = 9, 14.3%). Defects were most commonly located in the neck (n = 28, 41.8%). The mean flap area and arc of rotation were 326.4 ± 241.7 cm2 and 157.6 ± 33.2 degrees, respectively. Most flaps were myocutaneous (n = 48, 71.6%) and based on the dorsal scapular artery (n = 32, 47.8%). Complications occurred in 10 (14.9%) flaps. The flap's survival rate was 100% (n = 67). No instances of functional donor site morbidity were reported. The mean follow-up was 2.2 ± 1.8 years. CONCLUSION: This systematic review demonstrated the reliability of the pedicled trapezius flap in pediatric H&N reconstruction, with a low complication rate, no reports of functional donor site morbidity, and a 100% flap survival rate. The flap's substantial surface area, bulk, and arc of rotation contribute to its efficacy in covering soft tissue defects ranging from the proximal neck to the vertex of the scalp. The pedicled trapezius flap is a viable option for pediatric H&N reconstruction.

Microbial phenotypic heterogeneity in response to a metabolic toxin: Continuous, dynamically shifting distribution of formaldehyde tolerance in Methylobacterium extorquens populations.

While microbiologists often make the simplifying assumption that genotype determines phenotype in a given environment, it is becoming increasingly apparent that phenotypic heterogeneity (in which one genotype generates multiple phenotypes simultaneously even in a uniform environment) is common in many microbial populations. The importance of phenotypic heterogeneity has been demonstrated in a number of model systems involving binary phenotypic states (e.g., growth/non-growth); however, less is known about systems involving phenotype distributions that are continuous across an environmental gradient, and how those distributions change when the environment changes. Here, we describe a novel instance of phenotypic diversity in tolerance to a metabolic toxin within wild-type populations of Methylobacterium extorquens, a ubiquitous phyllosphere methylotroph capable of growing on the methanol periodically released from plant leaves. The first intermediate in methanol metabolism is formaldehyde, a potent cellular toxin that is lethal in high concentrations. We have found that at moderate concentrations, formaldehyde tolerance in M. extorquens is heterogeneous, with a cell's minimum tolerance level ranging between 0 mM and 8 mM. Tolerant cells have a distinct gene expression profile from non-tolerant cells. This form of heterogeneity is continuous in terms of threshold (the formaldehyde concentration where growth ceases), yet binary in outcome (at a given formaldehyde concentration, cells either grow normally or die, with no intermediate phenotype), and it is not associated with any detectable genetic mutations. Moreover, tolerance distributions within the population are dynamic, changing over time in response to growth conditions. We characterized this phenomenon using bulk liquid culture experiments, colony growth tracking, flow cytometry, single-cell time-lapse microscopy, transcriptomics, and genome resequencing. Finally, we used mathematical modeling to better understand the processes by which cells change phenotype, and found evidence for both stochastic, bidirectional phenotypic diversification and responsive, directed phenotypic shifts, depending on the growth substrate and the presence of toxin.

Steroid Use in Palatoplasty: A Single Surgeon Comparative Retrospective Cohort Study.

BACKGROUND: Fistula rates in cleft palate repair vary by technique, surgeon, and institution. Although steroids are commonly used in airway surgery, many plastic surgeons are reluctant to use steroids because of concerns with wound healing. This study aims to assess outcomes and safety of steroid use in Furlow palatoplasty and determine its impact on fistula formation. METHODS: A retrospective cohort study was done of all cleft palate surgeries performed by a single surgeon between 2010 and 2014. Data reviewed included demographics, type of cleft, steroid use, length of surgery, length of stay, and fistula formation rate. RESULTS: One hundred thirty-five patients underwent palatoplasty, of which 101 received steroids and 34 did not. The mean age was 4.6 years. A total of 42.2% of patients underwent primary palatoplasty, 48.1% underwent submucous cleft palatoplasty, and 9.7% underwent conversion palatoplasty. The overall fistula rate was 1.5% and was comparable between the 2 groups (steroids = 2.0%, no steroids = 0.0%, P = 0.558), and all occurred in primary palatoplasty patients. The average length of stay in the hospital was shorter among patients receiving steroids (steroids = 2.0 days, no steroids = 2.5 days, P < 0.05). CONCLUSIONS: Steroid use in cleft palate surgery appears to be safe and likely not associated with impaired wound healing or increased fistula formation. It may also shorten length of hospitalization.

Formaldehyde-responsive proteins, TtmR and EfgA, reveal a tradeoff between formaldehyde resistance and efficient transition to methylotrophy in Methylorubrum extorquens.

For bacteria to thrive they must be well-adapted to their environmental niche, which may involve specialized metabolism, timely adaptation to shifting environments, and/or the ability to mitigate numerous stressors. These attributes are highly dependent on cellular machinery that can sense both the external and intracellular environment. Methylorubrum extorquens is an extensively studied facultative methylotroph, an organism that can use single-carbon compounds as their sole source of carbon and energy. In methylotrophic metabolism, carbon flows through formaldehyde as a central metabolite; thus, formaldehyde is both an obligate metabolite and a metabolic stressor. Via the one-carbon dissimilation pathway, free formaldehyde is rapidly incorporated by formaldehyde activating enzyme (Fae), which is constitutively expressed at high levels. In the presence of elevated formaldehyde levels, a recently identified formaldehyde-sensing protein, EfgA, induces growth arrest. Herein, we describe TtmR, a formaldehyde-responsive transcription factor that, like EfgA, modulates formaldehyde resistance. TtmR is a member of the MarR family of transcription factors and impacts the expression of 75 genes distributed throughout the genome, many of which are transcription factors and/or involved in stress response, including efgA Notably, when M. extorquens is adapting its metabolic network during the transition to methylotrophy, efgA and ttmR mutants experience an imbalance in formaldehyde production and a notable growth delay. Although methylotrophy necessitates that M. extorquens maintain a relatively high level of formaldehyde tolerance, this work reveals a tradeoff between formaldehyde resistance and the efficient transition to methylotrophic growth and suggests that TtmR and EfgA play a pivotal role in maintaining this balance.Importance: All organisms produce formaldehyde as a byproduct of enzymatic reactions and as a degradation product of metabolites. The ubiquity of formaldehyde in cellular biology suggests all organisms have evolved mechanisms of mitigating formaldehyde toxicity. However, formaldehyde-sensing is poorly described and prevention of formaldehyde-induced damage is primarily understood in the context of detoxification. Here we use an organism that is regularly exposed to elevated intracellular formaldehyde concentrations through high-flux one-carbon utilization pathways to gain insight into the role of formaldehyde-responsive proteins that modulate formaldehyde resistance. Using a combination of genetic and transcriptomic analyses, we identify dozens of genes putatively involved in formaldehyde resistance, determined the relationship between two different formaldehyde response systems and identified an inherent tradeoff between formaldehyde resistance and optimal transition to methylotrophic metabolism.

Timing of Nerve Recovery After Nerve Grafting in Obstetrical Brachial Plexus Palsy Patients With Isolated Upper Trunk Neuromas.

BACKGROUND: The timing of nerve recovery after nerve grafting in obstetrical brachial plexus palsy patients has not been well reported. One prior study reported a return to baseline function at 3 to 6 months postoperatively. However, there is a paucity of studies to corroborate this timing, and there have been no studies delineating the timeline to obtain clinically meaningful function. METHODS: OBPP patients with upper trunk neuromas-in-continuity who were treated with resection and sural nerve grafting at a single institution were studied. Time to return to baseline function was assessed by Active Movement Scale (AMS) scores preoperatively and postoperatively. Time to clinically meaningful function, defined as an AMS score of ≥6, was also assessed. RESULTS: Eleven patients with isolated upper trunk neuromas-in-continuity underwent excision and reversed sural nerve grafting. Three of 11 patients also underwent spinal accessory to suprascapular nerve transfers. Average age at surgery was 9.8 ± 1.9 months. One patient did not have follow-up data and was excluded. Average follow-up was 37.1 ± 16.8 months. Average return to baseline AMS score was approximately 4 to 8 months for shoulder abduction, shoulder flexion, shoulder external rotation, elbow flexion, and forearm supination. Clinically meaningful function was obtained in most patients between 9 and 15 months. The remaining patients who did not achieve clinically meaningful function had all obtained scores of 5, which reflects less than one half normal range of motion against gravity. CONCLUSIONS: Nerve recovery after surgical intervention in OBPP patients who undergo resection of an upper trunk neuroma-in-continuity and nerve grafting is more rapid than in adults but longer than previously reported in OBPP literature. This study provides an important data point in delineating the timeline of nerve recovery.

Trypomastigote Excretory Secretory Antigen Blot Is Associated With Trypanosoma cruzi Load and Detects Congenital T. cruzi Infection in Neonates, Using Anti-Shed Acute Phase Antigen Immunoglobulin M.

Background: Congenital Trypanosoma cruzi infection accounts for an estimated 22% of new cases of Chagas disease in Latin America. However, neonatal diagnosis is challenging, as 9-month follow-up for immunoglobulin G testing is poor, quantitative polymerase chain reaction (qPCR) analysis is not routinely performed, and the micromethod misses ≥40% of congenital infections. Methods: Biorepository samples from new mothers and their infants from Piura, Peru, (an area of nonendemicity), and Santa Cruz, Bolivia (an area of endemicity) were accessed. Infant specimens were assessed using the micromethod, qPCR analysis, and a trypomastigote excretory secretory antigen (TESA) blot for detection of immunoglobulin M (IgM)-specific shed acute phase antigen (SAPA) bands, using qPCR as the gold standard. Results: When compared to qPCR, IgM TESA blot was both sensitive and specific for congenital Chagas disease diagnosis. Cumulative sensitivity (whether only 4 bands or all 6 bands were present) was 80% (95% confidence interval [CI], 59%-92%). Specificity was 94% (95% CI, 92%-96%) in the area of endemicity and 100% in the area of nonendemicity. SAPA bands occurred sequentially and in pairs, and parasite loads correlated highly with the number of SAPA bands present. The micromethod detected infection in fewer than half of infected infants. Conclusions: The IgM TESA blot for detection of SAPA bands is rapid, relatively inexpensive, and more sensitive than the micromethod and may be a useful point-of-care test for detection of congenital T. cruzi infection.

Manganese Is Required for the Rapid Recovery of DNA Synthesis following Oxidative Challenge in Escherichia coli.

Divalent metals such as iron and manganese play an important role in the cellular response to oxidative challenges and are required as cofactors by many enzymes. However, how these metals affect replication after oxidative challenge is not known. Here, we show that replication in Escherichia coli is inhibited following a challenge with hydrogen peroxide and requires manganese for the rapid recovery of DNA synthesis. We show that the manganese-dependent recovery of DNA synthesis occurs independent of lesion repair, modestly improves cell survival, and is associated with elevated rates of mutagenesis. The Mn-dependent mutagenesis involves both replicative and translesion polymerases and requires prior disruption by H2O2 to occur. Taking these findings together, we propose that replication in E. coli is likely to utilize an iron-dependent enzyme(s) that becomes oxidized and inactivated during oxidative challenges. The data suggest that manganese remetallates these or alternative enzymes to allow genomic DNA replication to resume, although with reduced fidelity.IMPORTANCE Iron and manganese play important roles in how cell's cope with oxygen stress. However, how these metals affect the ability of cells to replicate after oxidative challenges is not known. Here, we show that replication in Escherichia coli is inhibited following a challenge with hydrogen peroxide and requires manganese for the rapid recovery of DNA synthesis. The manganese-dependent recovery of DNA synthesis occurs independently of lesion repair and modestly improves survival, but it also increases the mutation rate in cells. The results imply that replication in E. coli is likely to utilize an iron-dependent enzyme(s) that becomes oxidized and inactivated during oxidative challenges. We propose that manganese remetallates these or alternative enzymes to allow genomic DNA replication to resume, although with reduced fidelity.

Deep nirS amplicon sequencing of San Francisco Bay sediments enables prediction of geography and environmental conditions from denitrifying community composition.

Denitrification is a dominant nitrogen loss process in the sediments of San Francisco Bay. In this study, we sought to understand the ecology of denitrifying bacteria by using next-generation sequencing (NGS) to survey the diversity of a denitrification functional gene, nirS (encoding cytchrome-cd1 nitrite reductase), along the salinity gradient of San Francisco Bay over the course of a year. We compared our dataset to a library of nirS sequences obtained previously from the same samples by standard PCR cloning and Sanger sequencing, and showed that both methods similarly demonstrated geography, salinity and, to a lesser extent, nitrogen, to be strong determinants of community composition. Furthermore, the depth afforded by NGS enabled novel techniques for measuring the association between environment and community composition. We used Random Forests modelling to demonstrate that the site and salinity of a sample could be predicted from its nirS sequences, and to identify indicator taxa associated with those environmental characteristics. This work contributes significantly to our understanding of the distribution and dynamics of denitrifying communities in San Francisco Bay, and provides valuable tools for the further study of this key N-cycling guild in all estuarine systems.

Spatiotemporal Characterization of San Francisco Bay Denitrifying Communities: a Comparison of nirK and nirS Diversity and Abundance.

Denitrifying bacteria play a critical role in the estuarine nitrogen cycle. Through the transformation of nitrate into nitrogen gas, these organisms contribute to the loss of bioavailable (i.e., fixed) nitrogen from low-oxygen environments such as estuary sediments. Denitrifiers have been shown to vary in abundance and diversity across the spatial environmental gradients that characterize estuaries, such as salinity and nitrogen availability; however, little is known about how their communities change in response to temporal changes in those environmental properties. Here, we present a 1-year survey of sediment denitrifier communities along the estuarine salinity gradient of San Francisco Bay. We used quantitative PCR and sequencing of functional genes coding for a key denitrifying enzyme, dissimilatory nitrite reductase, to compare two groups of denitrifiers: those with nirK (encoding copper-dependent nitrite reductase) and those with nirS (encoding the cytochrome-cd 1-dependent variant). We found that nirS was consistently more abundant and more diverse than nirK in all parts of the estuary. The abundances of the two genes were tightly linked across space but differed temporally, with nirK peaking when temperature was low and nirS peaking when nitrate was high. Likewise, the diversity and composition of nirK- versus nirS-type communities differed in their responses to seasonal variations, though both were strongly determined by site. Furthermore, our sequence libraries detected deeply branching clades with no cultured isolates, evidence of enormous diversity within the denitrifiers that remains to be explored.

The chemical neighborhood of cells in a diffusion-limited system.

Microorganisms follow us everywhere, and they will be essential to sustaining long-term human space exploration through applications such as vitamin synthesis, biomining, and more. Establishing a sustainable presence in space therefore requires that we better understand how stress due to the altered physical conditions of spaceflight affects our companion organisms. In microgravity environments such as orbital space stations, microorganisms likely experience the change in gravity primarily through changes in fluid mixing processes. Without sedimentation and density-driven convection, diffusion becomes the primary process governing the movement of growth substrates and wastes for microbial cells in suspension culture. Non-motile cells might therefore develop a substrate-deficient "zone of depletion" and experience stress due to starvation and/or waste build-up. This would in turn impact the concentration-dependent uptake rate of growth substrates and could be the cause of the altered growth rates previously observed in microorganisms in spaceflight and in ground-simulated microgravity. To better understand the extent of these concentration differences and their potential influence on substrate uptake rates, we used both an analytical solution and finite difference method to visualize concentration fields around individual cells. We modeled diffusion, using Fick's Second Law, and nutrient uptake, using Michaelis-Menten kinetics, and assessed how that distribution varies in systems with multiple cells and varied geometries. We determined the radius of the zone of depletion, within which cells had reduced the substrate concentration by 10%, to be 5.04 mm for an individual Escherichia coli cell in the conditions we simulated. However, we saw a synergistic effect with multiple cells near each other: multiple cells in close proximity decreased the surrounding concentration by almost 95% from the initial substrate concentration. Our calculations provide researchers an inside look at suspension culture behavior in the diffusion-limited environment of microgravity at the scale of individual cells.

Morphometry of the lateral orbitofrontal cortex is associated with eating dispositions in early adolescence: findings from a large population-based study.

Early adolescence is a critical period for eating behaviors as children gain autonomy around food choice and peer influences increase in potency. From a neurodevelopmental perspective, significant structural changes take place in the prefrontal cortex during this time, including the orbitofrontal cortex (OFC), which is involved in socially contextualized decision-making. We examined the morphological features of the OFC in relation to food choice in a sample of 10 309 early adolescent children from the Adolescent Brain and Cognitive Development Study. Structural parameters of the OFC and insula were examined for relationships with two important aspects of food choice: limiting the consumption of fast/fried food and maximizing the consumption of nutritious foods. Raw, partially adjusted and fully adjusted models were evaluated. Findings revealed that a larger surface area of the lateral OFC was associated with higher odds of limiting fast/fried food consumption in raw [odds ratio (OR) = 1.07, confidence interval (CI): 1.02, 1.12, P = 0.002, PFDR = 0.012], partially adjusted (OR = 1.11, CI: 1.03, 1.19, P = 0.004, PFDR = 0.024) and fully adjusted models (OR = 1.11, CI: 1.03, 1.19, P = 0.006, PFDR = 0.036). In contrast, a larger insula volume was associated with lower odds of maximizing healthy foods in raw (OR = 0.94, CI: 0.91, 0.97, P <0.001, PFDR = 0.003) and partially adjusted (OR = 0.93, CI: 0.88, 0.98, P = 0.008, PFDR = 0.048) models. These findings refine our understanding of the OFC as a network node implicated in socially mediated eating behaviors.

Neurocognitive and psychiatric symptoms following infection with COVID-19: Evidence from laboratory and population studies.

Objective: The objective of the current investigation was to examine associations between symptomatic COVID-19 history, neurocognitive function, and psychiatric symptoms using cognitive task performance, functional brain imaging, and a prospective population survey. Methods: Study 1 was a laboratory study conducted between 3 May 2022 and 16 Nov 2022 involving 120 fully vaccinated community dwelling adults between 18 and 84 years of age (Mage = 31.96 (SD = 20.71), 63.3% female). In this cross-sectional study we examined the association between symptomatic COVID-19 infection history and performance on three computer tasks assessing cognitive function (Flanker interference, delay discounting and simple reaction time) and measured oxygen saturation within the prefrontal cortex using functional near infrared spectroscopy (fNIRS). Study 2 was a 2-wave population survey undertaken between 28 September 2021 and 21 March 2022, examining the prospective relationship between symptomatic COVID-19 and self-reported symptoms of cognitive dysfunction, depressive symptoms, anxiety symptoms, and agitation at 6-month follow up. The sample (N = 2,002, M age = 37.0, SD = 10.4; 60.8% female) was collected using a quota process to ensure equal numbers of vaccinated and unvaccinated individuals. Structural equation modelling with latent variables was performed on the population-level data, evaluating the fit of the proposed mediational model of symptomatic COVID-19 to psychiatric symptoms through cognitive dysfunction. Results: Findings from Study 1 revealed significant effects of symptomatic COVID-19 history on Flanker interference and delay discounting. Effects on flanker performance were significantly stronger among older adult women (effect: 9.603, SE = 4.452, t = 2.157, p = .033), and were accompanied by task-related changes cerebral oxygenation at the right superior frontal gyrus (F (1, 143.1) = 4.729, p = .031). Additionally, those with a symptomatic COVID-19 infection history showed evidence of amplified delay discounting (coefficient = 0.4554, SE = 0.2208, t = 2.0629, p = .041). In Study 2, baseline symptomatic COVID-19 history was associated with self-reported cognitive dysfunction and a latent variable reflecting psychiatric symptoms of anxiety, depression and agitation at follow-up. Mediational analyses revealed evidence of cognitive mediation of clinically significant psychiatric outcomes: depression (indirect effect = 0.077, SE = 0.026, p = .003) and generalized anxiety (indirect effect = 0.060, SE = 0.021, p = .004). Conclusions: Converging findings from laboratory and population survey data support the conclusion that symptomatic COVID-19 infection is associated with task-related, functional imaging and self-reported indices of cognitive dysfunction as well as psychiatric symptoms. In some cases, these findings appear to be more amplified among women than men, and among older women than younger.

Rapid spectrophotometric detection for optimized production of landomycins and characterization of their therapeutic potential.

Microbial derived natural products remain a major source of structurally diverse bioactive compounds and chemical scaffolds that have potential as new therapeutics to target drug resistant pathogens and cancers. In particular, genome mining has revealed the vast number of cryptic or low yield biosynthetic gene clusters in the genus Streptomyces . Here, we describe our efforts to improve yields of landomycins - angucycline family polyketides under investigation as cancer therapeutics - by a genetically modified Streptomyces cyanogenus 136. After simplifying the extraction process from S. cyanogenus cultures, we identified a wavelength at which the major landomycin products absorb in culture extracts, which we used to systematically explore culture medium compositions to improve total landomycin titers. Through correlational analysis, we simplified the culture optimization process by identifying an alternative wavelength at which culture supernatants absorb yet is representative of total landomycin titers. Using the subsequently improved sample throughput, we explored landomycin production during the culturing process to further increase landomycin yield and reduce culture time. Testing the antimicrobial activity of the isolated landomycins, we report broad inhibition of Gram-positive bacteria, inhibition of fungi by landomycinone, and broad landomycin resistance by Gram-negative bacteria that is likely mediated by exclusion of landomycins by the bacterial membrane. Finally, the anticancer activity of the isolated landomycins against A549 lung carcinoma cells agrees with previous reports on other cell lines that glycan chain length correlates with activity. Given the prevalence of natural products produced by Streptomyces , as well as the light-absorbing moieties common to bioactive natural products and their metabolic precursors, our method is relevant to improving the yields of other natural products of interest.