Chikungunya virus release is reduced by TIM-1 receptors through binding of envelope phosphatidylserine.

T-cell immunoglobin and mucin domain protein-1 (TIM-1) mediates entry of chikungunya virus (CHIKV) into some mammalian cells through the interaction with envelope phospholipids. While this interaction enhances entry, TIM-1 has been shown to tether newly formed HIV and Ebola virus particles, limiting their efficient release. In this study, we investigate the ability of surface receptors such as TIM-1 to sequester newly budded virions on the surface of infected cells. We established a luminescence reporter system to produce chikungunya viral particles that integrate nano-luciferase and easily quantify viral particles. We found that TIM-1 on the surface of host cells significantly reduced CHIKV release efficiency in comparison to other entry factors. Removal of cell surface TIM-1 through direct cellular knock-out or altering the cellular lipid distribution enhanced CHIKV release. Over the course of infection, CHIKV was able to counteract the tethering effect by gradually decreasing the surface levels of TIM-1 in a process mediated by the nonstructural protein 2. This study highlights the importance of phosphatidylserine receptors in mediating not only the entry of CHIKV but also its release and could aid in developing cell lines capable of enhanced vaccine production. IMPORTANCE: Chikungunya virus (CHIKV) is an enveloped alphavirus transmitted by the bites of infectious mosquitoes. Infection with CHIKV results in the development of fever, joint pain, and arthralgia that can become chronic and last for months after infection. Prevention of this disease is still highly focused on vector control strategies. In December 2023, a new live attenuated vaccine against CHIKV was approved by the FDA. We aimed to study the cellular factors involved in CHIKV release, to better understand CHIKV's ability to efficiently infect and spread among a wide variety of cell lines. We found that TIM-1 receptors can significantly abrogate CHIKV's ability to efficiently exit infected cells. This information can be beneficial for maximizing viral particle production in laboratory settings and during vaccine manufacturing.

Model analysis of post-fire management and potential reburn fire behavior.

Recent trends in wildfire area burned have been characterized by large patches with high densities of standing dead trees, well outside of historical range of variability in many areas and presenting forest managers with difficult decisions regarding post-fire management. Post-fire tree harvesting, commonly called salvage logging, is a controversial management tactic that is often undertaken to recoup economic loss and, more recently, also to reduce future fuel hazard, especially when coupled with surface fuel reduction. It is unclear, however, whether the reductions in future fuels translate to meaningful changes to reburn fire behavior, particularly in the context of potentially detrimental effects of harvest on other ecosystem services. We used observed post-fire snag structure in four high severity burn scars located in the Western United States that had variable post-fire snag basal area (13.3-63.9 mg ha-2) to initialize a simulation study of future coarse and fine woody fuel hazard and associated reburn fire behavior and effects. We compared untreated controls to intensive and intermediate intensity harvest treatments, both simulated and actual. All treatments showed some number of years of extreme fire behavior during which flame lengths exceeded thresholds associated with wildfire resistance to control, implying that future fuel reductions achieved by the treatments did not translate to conditions conducive for effective reburn fire management. Harvested stands had less severe soil fire effects (soil heating and smoldering duration) than untreated controls, explained by lower predicted peak coarse woody fuels (CWD) in the harvested stands. At higher pre-treatment snag basal area, harvested stands better maintained CWD within the range desired to maintain ecosystem functions such as nutrient cycling and wildlife habitat. These simulation results indicate that, even with reduced fuel hazard, salvage treatments may still be associated with severe fire behavior for some time after wildfire, but achieved reductions in coarse woody fuels may also reduce some soil fire effects. Tradeoffs in the effects of post-fire harvest must be considered carefully in the context of forest regeneration, local conditions that govern salvage methods, snag fall and decomposition, and associated potential reburn fire effects.

The Relationship Between Broadband Speeds, Device Type, Demographic Characteristics, and Care-Seeking Via Telehealth.

Background: This study sought to examine the complex relationship between individual and environmental characteristics, broadband access, device type (computer or smartphone), and telehealth utilization as it relates to the digital divide. Methods: We analyzed a combination of electronic health record and publicly available zip code-level data for 2,770 men seeking treatment on a large, nationally available, direct-to-consumer telehealth platform. Using logistic regression, we determined the likelihood of accessing the platform through a smartphone (vs. a computer) based on key features of the environment, including broadband access and income, and demographic characteristics, including age and race. Results: We found that living in areas with higher rates of broadband adoption significantly decreased the likelihood of accessing virtual care using a smartphone (odds ratio [OR] = 0.17, p < 0.001). Compared with the 18-29 age category, the odds of accessing virtual care using a smartphone decreased for men between the age categories of 40-59 (OR = 0.63, p < 0.01) and over 60 (OR = 0.29, p < 0.001) years. Belonging to historically marginalized communities of color (Black, Hispanic, and Native American) almost doubled the odds of using a smartphone to access the platform (OR = 1.8, p < 0.001). Broadband availability and median area income were not significantly associated with mobile use. Conclusions: Telehealth platform design and policy solutions intended to expand access to virtual care should be flexible enough to accommodate the sometimes competing needs of patients who are at the greatest risk of being left behind.

Effectiveness and Safety of Twice- Versus Thrice-Daily Subcutaneous Heparin for Venous Thromboembolism Prophylaxis at a Large Academic Medical Center.

BACKGROUND: Dosing variation of subcutaneous unfractionated heparin (UFH) exist for venous thromboembolism prophylaxis (VTEP). OBJECTIVE: The purpose of this study was to compare the safety and effectiveness of thrice-daily (TID) versus twice-daily (BID) administration of UFH during a heparin shortage for VTEP. METHODS: A single-center retrospective analysis was conducted in patients with orders for BID subcutaneous UFH during a heparin shortage from September 1, 2019, to February 4, 2020. These patients were matched to patients with TID subcutaneous UFH orders from January 1, 2019, to May 31, 2019. The primary outcome was the incidence of deep-vein thrombosis or pulmonary embolism confirmed by imaging during hospitalization. The secondary outcome was the incidence of major or clinically relevant nonmajor bleeding events as defined by International Society on Thrombosis and Haemostasis (ISTH) definitions. RESULTS: A total of 277 patients with orders for BID UFH and meeting inclusion criteria were evaluated and matched to patients who received TID UFH. After the exclusion criteria were implemented, 510 patients remained in the TID group. The primary outcome occurred in 4% of patients in the BID group and 3% in the TID group (P = 0.645). Major bleeding or clinically relevant nonmajor bleeding events occurred in 10% of patients in the BID group and 8% in the TID group (P = 0.310). CONCLUSION AND RELEVANCE: There was no difference in effectiveness or safety of TID versus BID subcutaneous UFH for VTEP. During a heparin shortage, transitioning patients to BID UFH for VTEP to conserve supply may be considered.

Economic Evaluation of a Pharmacist-Led 5-Day Therapeutic Hold of IV Levothyroxine at an Academic Medical Center.

Objective: Providers often admit patients with active outpatient prescriptions for levothyroxine. During an inpatient admission, providers may instruct critically ill patients to take nothing by mouth, or nil per os (NPO). Thus, they may prescribe the intravenous (IV) formulation of levothyroxine during this period. However, levothyroxine possesses a prolonged half-life of up to 7 days; therefore, immediate transition to IV levothyroxine may not be clinically necessary in the acute NPO setting. Intravenous levothyroxine is significantly more expensive than equivalent oral doses and may prove to be a financial burden for an institution. By understanding the pharmacokinetic properties of levothyroxine, we implemented a cost-saving initiative involving a 5-day therapeutic hold of IV levothyroxine. Methods: This was a retrospective evaluation in 2 intensive care units (ICU): a 20-bed surgical/trauma ICU and an 18-bed mixed medical/surgical ICU. Patient data, utilization data, and documented pharmacist interventions were collected for 6 months prior to implementation of the 5-day IV levothyroxine therapeutic hold and for 6 months post-implementation. All patients prescribed IV levothyroxine during these timeframes were included. Results: During the 6-month pre-implementation phase, 674 doses (691 vials) of IV levothyroxine for 77 unique patients were dispensed from the 2 ICUs. During the 6-month post-implementation phase, 168 doses (188 vials) of IV levothyroxine were dispensed for 44 unique patients. Of the 44 patients (48 orders) who still received IV levothyroxine, 22.9% of orders were deemed clinically necessary by the pharmacist and were not recommended to be held under the protocol, 64.6% were due to the verifying pharmacist being unaware of the protocol, 8.3% of orders were due to protocol non-compliance, and 4.2% were verified after the 5-day hold was complete as the patient remained NPO. This pharmacy-led initiative resulted in a 75% decrease in usage post-implementation and an estimated annualized savings of $80,000. Conclusion: A pharmacy-led initiative comprised of a 5-day therapeutic hold of IV levothyroxine was feasible and led to a 75% reduction in usage and cost over a 6-month period in 2 ICU's. Future steps include additional staff education for improved protocol adherence and expanding the protocol institution-wide for an even greater cost-savings potential.

The Local Inflammatory Profile and Predictors of Treatment Success in Subarachnoid Neurocysticercosis.

BACKGROUND: Subarachnoid neurocysticercosis (SANCC) represents the most severe and difficult to treat form of neurocysticercosis. The inflammatory response contributes significantly to the morbidity and mortality of the disease. This study sought to understand the nature and evolution of the inflammation associated with SANCC, and evaluate for predictors of time to cure. METHODS: There were 16 subjects with SANCC (basilar cistern, sylvian fissure, and/or spinal involvement) during active infection who had cerebrospinal fluid (CSF) cytokine and chemokine profiling, of whom 9 had a second CSF sample at (or following) the time of cure. The relationships between clinical parameters and cytokine/chemokine results were assessed. RESULTS: Compared to pools of healthy donor CSF, those with active SANCC showed a significant (P < .05) increase in chemokines and cytokines associated with Type 1 immunity (interferon [IFN] γ, interleukin [IL] 12p70, C-X-C Motif Ligand 10 CXCL-10); Type 2 immunity (IL-10, IL-13); IFNα2; and the chemokines Macrophage inflammatory protein MIP-1α/CCL3, MIP-1ß/CCL4, and Vascular Endothelial Growth Factor VEGF that appears to be locally (central nervous system [CNS]) produced. Compared to those with active disease, those with CSF taken at the time of cure showed a significant decrease in most of these chemokines and cytokines. Despite this, CSF from cured SANCC patients had levels of IL-10 (P = .039), CXCL-10 (P = .039), and IL-12p70 (P = .044) above those seen in CSF from uninfected subjects. High ratios of IL-12p70/IL-10 early in infections were associated with a shorter time to cure (r = -0.559; P = .027), and a high Taenia solium burden (by quantitative polymerase chain reaction) was associated with longer times to cure (r = 0.84; P = .003). CONCLUSIONS: SANCC is associated with a marked, CNS-localized cytokine-/chemokine-driven inflammatory response that largely decreases with curative therapy, though some analytes persisted above the normal range. The relative balance between proinflammatory and regulatory cytokines may be an important determinant for a cure in SANCC.

Reduced social investigation and increased injurious behavior in transgenic 5xFAD mice.

Social withdrawal and agitation/aggression are common behavioral and psychological symptoms of dementia presented by Alzheimer's disease (AD) patients, with males exhibiting more aggressive behaviors than females. Some transgenic mouse models of AD also exhibit social withdrawal and aggression, but many of these models only recapitulate the early stages of the disease. By comparison, the 5xFAD mouse model of AD exhibits rapid, progressive neurodegeneration, and is suitable for modeling cognitive and behavioral deficits at early, mid-, and late-stage disease progression. Anecdotal reports suggest that transgenic 5xFAD males exhibit high levels of aggression compared to wild-type controls, but to date, indirect genetic effects in this strain have not been studied. We measured home-cage behaviors in 5xFAD males housed in three different group-housing conditions (transgenic-only, wild-type only, and mixed-genotype) and social approach behaviors when exposed to a novel free-roaming or restrained, wild-type or transgenic conspecific. Transgenic-only home cages required earlier separation due to injuries arising from aggression compared to wild-type-only or mixed-genotype cages, despite no obvious increase in the frequency of aggressive behaviors. Transgenic 5xFAD males and females also spent less time investigating free-roaming conspecifics compared to wild-type controls, but they showed normal investigation of restrained conspecifics; the genotype of the conspecific did not affect approach behavior, and there was no aggression observed in transgenic males. These findings provide evidence in an animal model that amyloid pathology ultimately leads to avoidance of novel social stimuli, and that frequent interactions between individuals exhibiting an AD phenotype further exacerbates aggressive behaviors.

Gender intentional approaches to enhance health social enterprises in Africa: a qualitative study of constraints and strategies.

BACKGROUND: Health social enterprises are experimenting with community health worker (CHW) models that allow for various income-generating opportunities to motivate and incentivize CHWs. Although evidence shows that improving gender equality contributes to the achievement of health outcomes, gender-based constraints faced by CHWs working with social enterprises in Africa have not yet been empirically studied. This study is the first of its kind to address this important gap in knowledge. METHODS: We conducted 36 key informant interviews and 21 focus group discussions between 2016 and 2019 (for a total of 175 individuals: 106 women and 69 men) with four health social enterprises in Uganda and Kenya and other related key stakeholders and domain experts. Interview and focus group transcripts were coded according to gender-based constraints and strategies for enhanced performance as well as key sites for intervention. RESULTS: We found that CHW programs can be more gender responsive. We introduce the Gender Integration Continuum for Health Social Enterprises as a tool that can help guide gender equality efforts. Data revealed female CHWs face seven unique gender-based constraints (compared to male CHWs): 1) higher time burden and lack of economic empowerment; 2) risks to personal safety; 3) lack of career advancement and leadership opportunities; 4) lack of access to needed equipment, medicines and transport; 5) lack of access to capital; 6) lack of access to social support and networking opportunities; and 7) insufficient financial and non-financial incentives. Data also revealed four key areas of intervention: 1) the health social enterprise; 2) the CHW; 3) the CHW's partner; and 4) the CHW's patients. In each of the four areas, gender responsive strategies were identified to overcome constraints and contribute to improved gender equality and community health outcomes. CONCLUSIONS: This is the first study of its kind to identify the key gender-based constraints and gender responsive strategies for health social enterprises in Africa using CHWs. Findings can assist organizations working with CHWs in Africa (social enterprises, governments or non-governmental organizations) to develop gender responsive strategies that increase the gender and health outcomes while improving gender equality for CHWs, their families, and their communities.

A Novel, Highly Sensitive Quantitative Polymerase Chain Reaction Assay for the Diagnosis of Subarachnoid and Ventricular Neurocysticercosis and for Assessing Responses to Treatment.

BACKGROUND: Treatment of subarachnoid neurocysticercosis (NCC) is complicated, and assays that can guide treatment are not widely available. The reproducibility and scalability of molecular-based biomarkers would be of great use. METHODS: The Taenia solium genome was mined and primers and probes were designed to target repeats with the highest coverage; the most sensitive, specific, and efficient repeat (TsolR13) was selected for clinical testing. We tested 46 plasma samples and 36 cerebral spinal fluid (CSF) samples taken from patients with subarachnoid or ventricular disease using quantitative polymerase chain reaction (qPCR). RESULTS: The analytic sensitivity of TsolR13 was 97.3% at 240 attograms (ag) of T. solium genomic DNA and 100% analytic specificity. The clinical sensitivity in detecting active subarachnoid or ventricular disease in symptomatic patients was 100% in CSF and 81.3% in plasma. The predictive ability to distinguish active from cured disease was better for CSF (94.4% of those cured had negative qPCR results) than for plasma (86.7% of those cured tested negative). Some subjects also had plasma DNA detectable intermittently for years after being cured. Overall, the test performance was equivalent to T. solium antigen detection. CONCLUSIONS: A qPCR test for the detection of the highly repetitive Tsol13 sequence has been developed and shown to be highly sensitive and specific for NCC, but also useful as a test of cure in CSF and for the definitive diagnosis of NCC in plasma.

Evaluation of Serotonin Release Assay and Enzyme-Linked Immunosorbent Assay Optical Density Thresholds for Heparin-Induced Thrombocytopenia in Patients on Extracorporeal Membrane Oxygenation.

OBJECTIVES: Heparin-induced thrombocytopenia is a recognized concern in patients on extracorporeal life support. The purpose of this study was to evaluate the applicability of an enzyme-linked immunosorbent assay optical density threshold less than 1 to rule out heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation. DESIGN: Retrospective, single-center study. SETTING: Patients were recruited from a prospectively maintained database of all patients on extracorporeal membrane oxygenation from 2012 to 2018 at a tertiary referral center. PATIENTS: Forty-seven patients on extracorporeal membrane oxygenation support. INTERVENTIONS: The primary objective was to evaluate the application of enzyme-linked immunosorbent assay optical density thresholds and the serotonin release assay in patients on extracorporeal membrane oxygenation. Patients were divided into two cohorts, serotonin release assay negative and serotonin release assay positive. In order to perform a sensitivity and specificity analysis of enzyme-linked immunosorbent assay optical density thresholds, heparin-induced thrombocytopenia negative was defined as an optical density less than 1.0 and heparin-induced thrombocytopenia positive as an optical density greater than or equal to 1.0. MEASUREMENTS AND MAIN RESULTS: Utilizing the prespecified optical density thresholds, a specificity and negative predictive value of 89% and 95% were achieved, respectively. CONCLUSIONS: This assessment has helped to identify optical density thresholds for patients undergoing extracorporeal membrane oxygenation. Our data suggest that an optical density threshold of 1.0 may aid clinicians in objectively ruling out heparin-induced thrombocytopenia without sending a confirmatory serotonin release assay. Increasing the optical density threshold to 1.0 resulted in a high specificity and negative predictive value.

Adherence to guidelines across different specialties to prevent infections in patients undergoing immunosuppressive therapies.

BACKGROUND: Substantial numbers of patients are now receiving either immunosuppressive therapies or chemotherapy. There are significant risks in such patients of developing opportunistic infections or re-activation of latent infections, with higher associated morbidity and mortality. The aim of this quality improvement project was to determine how effective 5 different specialties were in assessing and mitigating risks of developing opportunistic infections or re-activation of latent infections in patients undergoing immunosuppressive therapies. METHODS: This was a single centre audit where records of patients attending clinics providing immunosuppressive therapies were reviewed for the following: evidence of screening for blood-borne virus [BBV] infections, varicella and measles immunity, latent/active TB or hypogammaglobulinaemia, and whether appropriate vaccines had been advised or various infection risks discussed. These assessments were audited against both national and international guidelines, or a cross-specialty consensus guideline where specific recommendations were lacking. Two sub-populations were also analysed separately: patients receiving more potent immunosuppression and black and minority ethnic [BME] patients,. RESULTS: For the 204 patients fulfilling the inclusion criteria, BBV, varicella/measles and latent TB screening was inconsistent, as was advice for vaccinations, with few areas complying with specialty or consensus guidelines. Less than 10% of patients in one specialty were tested for HIV. In BME patients screening for HIV [60%], measles [0%] and varicella [40%] immunity and latent [30%] or active [20%] TB was low. Only 38% of patients receiving potent immunosuppression received Pneumocystis prophylaxis, with 3 of 4 specialties providing less than 15% of patients in this category with prophylaxis. CONCLUSIONS: Compliance with guidelines to mitigate risks of infection from immunosuppressive therapies was either inconsistent or poor for most specialties. New approaches to highlight such risks and assist appropriate pre-immunosuppression screening are needed.

Framing climate change and health: New Zealand's online news media.

Climate change is a major threat to public health worldwide. Conversely, well-designed action to mitigate climate change offers numerous opportunities to improve health and equity. Despite this, comprehensive climate action has not been forthcoming within New Zealand. The media plays an important role in shaping public opinion and support for policy change. Previous literature has suggested that certain types of framing may be more effective than others at encouraging support for climate action and policy. This includes positive, personally relevant framing, as well as key journalistic tools which appear counter-intuitive, such as an increase in human interest stories and 'sensationalist' framing. We undertook a qualitative thematic analysis of climate change and health media coverage in two online New Zealand news outlets to understand how the issue was framed, and how it may be framed more effectively to encourage climate action. We compared the framing used by journalists in mainstream media outlet the New Zealand Herald Online (NZHO) with that of contributors to independent news repository site Scoop. Content in both outlets emphasized the threat unchecked climate change poses to health, which overshadowed the positive health opportunities of climate action. The NZHO was more prone to negative framing, and more likely to favour stories which could be sensationalized and were international in scope. We considered the possible effectiveness of the framing we found for attracting greater media attention and encouraging support for climate action and policy.

Social network analysis and whole genome sequencing in a cohort study to investigate TB transmission in an educational setting.

BACKGROUND: TB outbreaks in educational institutions can result in significant transmission and pose a considerable threat to TB control. Investigation using traditional microbiological and epidemiological tools can lead to imprecise screening strategies due to difficulties characterising complex transmission networks. Application of whole genome sequencing (WGS) and social network analysis can provide additional information that may facilitate rapid directed public health action. We report the utility of these methods in combination with traditional approaches for the first time to investigate a TB outbreak in an educational setting. METHODS: Latent tuberculosis infection (LTBI) cases were screenees with a positive T-SPOT®.TB test. Active TB cases were defined through laboratory confirmation of M. tuberculosis on culture or through clinical or radiological findings consistent with infection. Epidemiological data were collected from institutional records and screenees. Samples were cultured and analysed using traditional M. tuberculosis typing and WGS. We undertook multivariable multinomial regression and social network analysis to identify exposures associated with case status and risk communities. RESULTS: We identified 189 LTBI cases (13.7% positivity rate) and nine active TB cases from 1377 persons screened. The LTBI positivity rate was 39.1% (99/253) among persons who shared a course with an infectious case (odds ratio 7.3, 95% confidence interval [CI] 5.2 to 10.3). The community structure analysis divided the students into five communities based on connectivity, as opposed to the 11 shared courses. Social network analysis identified that the community including the suspected index case was at significantly elevated risk of active disease (odds ratio 7.5, 95% CI 1.3 to 44.0) and contained eight persons who were lost to follow-up. Five sputum samples underwent WGS, four had zero single nucleotide polymorphism (SNP) differences and one had a single SNP difference. CONCLUSION: This study demonstrates the public health impact an undiagnosed case of active TB disease can have in an educational setting within a low incidence area. Social network analysis and whole genome sequencing provided greater insight to evolution of the transmission network and identification of communities of risk. These tools provide further information over traditional epidemiological and microbiological approaches to direct public health action in this setting.

Gender and health social enterprises in Africa: a research agenda.

BACKGROUND: Health social enterprises in Africa working with community health workers (CHWs) are growing rapidly but understudied. In particular, gender equality issues related to their work has important public health and equity implications. METHODS: Particularly suited for generating timely findings from reviews at the intersection of overlapping disciplines, we utilized the rapid evidence assessment (REA) methodology to identify key unanswered research questions at the intersection of the fields of gender equality, social enterprises and community health workers. The REA used a series of structured Google Scholar searches, expert interviews and bibliography reviews to identify 57 articles in the academic and grey literatures that met the study inclusion criteria. Articles were thematically coded to identify answers to "What are the most important research questions about the influence of gender on CHWs working with health social enterprises in Africa?" RESULTS: The analysis identified six key unanswered research questions relating to 1) equitable systems and structures; 2) training; 3) leadership development and career enhancement; 4) payment and incentives; 5) partner, household and community support; and 6) performance. CONCLUSION: This is the first study of its kind to identify the key unanswered research questions relevant to gender equality in health social enterprises in Africa using community health workers. As such, it sets out a research agenda for this newly emerging but rapidly developing area of research and practice with important public health implications.

Ancylostoma ceylanicum Hookworm in Myanmar Refugees, Thailand, 2012-2015.

During 2012-2015, US-bound refugees living in Myanmar-Thailand border camps (n = 1,839) were surveyed for hookworm infection and treatment response by using quantitative PCR. Samples were collected at 3 time points: after each of 2 treatments with albendazole and after resettlement in the United States. Baseline prevalence of Necator americanus hookworm was 25.4%, Ancylostoma duodenale 0%, and Ancylostoma ceylanicum (a zoonosis) 5.4%. Compared with N. americanus prevalence, A. ceylanicum hookworm prevalence peaked in younger age groups, and blood eosinophil concentrations during A. ceylanicum infection were higher than those for N. americanus infection. Female sex was associated with a lower risk for either hookworm infection. Cure rates after 1 dose of albendazole were greater for A. ceylanicum (93.3%) than N. americanus (65.9%) hookworm (p<0.001). Lower N. americanus hookworm cure rates were unrelated to ß-tubulin single-nucleotide polymorphisms at codons 200 or 167. A. ceylanicum hookworm infection might be more common in humans than previously recognized.

Chemical dispersants can suppress the activity of natural oil-degrading microorganisms.

During the Deepwater Horizon oil well blowout in the Gulf of Mexico, the application of 7 million liters of chemical dispersants aimed to stimulate microbial crude oil degradation by increasing the bioavailability of oil compounds. However, the effects of dispersants on oil biodegradation rates are debated. In laboratory experiments, we simulated environmental conditions comparable to the hydrocarbon-rich, 1,100 m deep plume that formed during the Deepwater Horizon discharge. The presence of dispersant significantly altered the microbial community composition through selection for potential dispersant-degrading Colwellia, which also bloomed in situ in Gulf deep waters during the discharge. In contrast, oil addition to deepwater samples in the absence of dispersant stimulated growth of natural hydrocarbon-degrading Marinobacter. In these deepwater microcosm experiments, dispersants did not enhance heterotrophic microbial activity or hydrocarbon oxidation rates. An experiment with surface seawater from an anthropogenically derived oil slick corroborated the deepwater microcosm results as inhibition of hydrocarbon turnover was observed in the presence of dispersants, suggesting that the microcosm findings are broadly applicable across marine habitats. Extrapolating this comprehensive dataset to real world scenarios questions whether dispersants stimulate microbial oil degradation in deep ocean waters and instead highlights that dispersants can exert a negative effect on microbial hydrocarbon degradation rates.

Spatial specificity and inheritance of adaptation in human visual cortex.

Adaptation at early stages of sensory processing can be propagated to downstream areas. Such inherited adaptation is a potential confound for functional magnetic resonance imaging (fMRI) techniques that use selectivity of adaptation to infer neuronal selectivity. However, the relative contributions of inherited and intrinsic adaptation at higher cortical stages, and the impact of inherited adaptation on downstream processing, remain unclear. Using fMRI, we investigated how adaptation to visual motion direction and orientation influences visually evoked responses in human V1 and extrastriate visual areas. To dissociate inherited from intrinsic adaptation, we quantified the spatial specificity of adaptation for each visual area as a measure of the receptive field sizes of the area where adaptation originated, predicting that adaptation originating in V1 should be more spatially specific than adaptation intrinsic to extrastriate visual cortex. In most extrastriate visual areas, the spatial specificity of adaptation did not differ from that in V1, suggesting that adaptation originated in V1. Only in one extrastriate area-MT-was the spatial specificity of direction-selective adaptation significantly broader than in V1, consistent with a combination of inherited V1 adaptation and intrinsic MT adaptation. Moreover, inherited adaptation effects could be both facilitatory and suppressive. These results suggest that adaptation at early visual processing stages can have widespread and profound effects on responses in extrastriate visual areas, placing important constraints on the use of fMRI adaptation techniques, while also demonstrating a general experimental strategy for systematically dissociating inherited from intrinsic adaptation by fMRI.

Towards a synthesis of frameworks in nutritional ecology: interacting effects of protein, carbohydrate and phosphorus on field cricket fitness.

Phosphorus has been identified as an important determinant of nutrition-related biological variation. The macronutrients protein (P) and carbohydrates (C), both alone and interactively, are known to affect animal performance. No study, however, has investigated the importance of phosphorus relative to dietary protein or carbohydrates, or the interactive effects of phosphorus with these macronutrients, on fitness-related traits in animals. We used a nutritional geometry framework to address this question in adult field crickets (Gryllus veletis). Our results showed that lifespan, weight gain, acoustic mate signalling and egg production were maximized on diets with different P : C ratios, that phosphorus did not positively affect any of these fitness traits, and that males and females had different optimal macronutrient intake ratios for reproductive performance. When given a choice, crickets selected diets that maximized both lifespan and reproductive performance by preferentially eating diets with low P : C ratios, and females selected diets with a higher P : C ratio than males. Conversely, phosphorus intake was not regulated. Overall, our findings highlight the importance of disentangling the influences of different nutrients, and of quantifying both their individual and interactive effects, on animal fitness traits, so as to gain a more integrative understanding of their nutritional ecology.

Dispersant addition, but not nutrients, stimulated blooms of multiple hydrocarbonoclastic genera in nutrient-replete coastal marine surface waters.

The range of impacts of chemical dispersants on indigenous marine microbial communities and their activity remains poorly constrained. We tested the response of nearshore surface waters chronically exposed to oil leakage from a downed platform and supplied with nutrients by the Mississippi River to Corexit dispersant and nutrient additions. As assessed using 14C-labeled tracers, hexadecane mineralization potential was orders of magnitude higher in all unamended samples than in previously assessed bathypelagic communities. Nutrient additions stimulated microbial mortality but did not affect community composition and had no generalizable effect on hydrocarbon mineralization potential. By contrast, Corexit amendments caused a rapid shift in community composition and a drawdown of inorganic nitrogen and orthophosphate though no generalizable effect on hydrocarbon mineralization potential. The hydrocarbonoclastic community's response to dispersants is largely driven by the relative availability of organic substrates and nutrients, underscoring the role of environmental conditions and multiple interacting stressors on hydrocarbon degradation potential.