Optical Properties of Water for Prediction of Wastewater Contamination, Human-Associated Bacteria, and Fecal Indicator Bacteria in Surface Water at Three Watershed Scales.

Relations between spectral absorbance and fluorescence properties of water and human-associated and fecal indicator bacteria were developed for facilitating field sensor applications to estimate wastewater contamination in waterways. Leaking wastewater conveyance infrastructure commonly contaminates receiving waters. Methods to quantify such contamination can be time consuming, expensive, and often nonspecific. Human-associated bacteria are wastewater specific but require discrete sampling and laboratory analyses, introducing latency. Human sewage has fluorescence and absorbance properties different than those of natural waters. To assist real-time field sensor development, this study investigated optical properties for use as surrogates for human-associated bacteria to estimate wastewater prevalence in environmental waters. Three spatial scales were studied: Eight watershed-scale sites, five subwatershed-scale sites, and 213 storm sewers and open channels within three small watersheds (small-scale sites) were sampled (996 total samples) for optical properties, human-associated bacteria, fecal indicator bacteria, and, for selected samples, human viruses. Regression analysis indicated that bacteria concentrations could be estimated by optical properties used in existing field sensors for watershed and subwatershed scales. Human virus occurrence increased with modeled human-associated bacteria concentration, providing confidence in these regressions as surrogates for wastewater contamination. Adequate regressions were not found for small-scale sites to reliably estimate bacteria concentrations likely due to inconsistent local sanitary sewer inputs.

Phoretic dispersal influences parasite population genetic structure.

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host-specific feather lice (Phthiraptera: Ischnocera) that co-occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, "wing lice" (Columbicola columbae) disperse phoretically by "hitchhiking" on pigeon flies (Diptera: Hippoboscidae), while "body lice" (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host-parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host-parasite cospeciation.

Molecular mechanisms of Slo2 K+ channel closure.

KEY POINTS: Intracellular Na+ -activated Slo2 potassium channels are in a closed state under normal physiological conditions, although their mechanisms of ion permeation gating are not well understood. A cryo-electron microscopy structure of Slo2.2 suggests that the ion permeation pathway of these channels is closed by a single constriction of the inner pore formed by the criss-crossing of the cytoplasmic ends of the S6 segments (the S6 bundle crossing) at a conserved Met residue. Functional characterization of mutant Slo2 channels suggests that hydrophobic interactions between Leu residues in the upper region of the S6 segments contribute to stabilizing the inner pore in a non-conducting state. Mutation of the conserved Met residues in the S6 segments to the negatively-charged Glu did not induce constitutive opening of Slo2.1 or Slo2.2, suggesting that ion permeation of Slo2 channels is not predominantly gated by the S6 bundle crossing. ABSTRACT: Large conductance K+ -selective Slo2 channels are in a closed state unless activated by elevated [Na+ ]i . Our previous studies suggested that the pore helix/selectivity filter serves as the activation gate in Slo2 channels. In the present study, we evaluated two other potential mechanisms for stabilization of Slo2 channels in a closed state: (1) dewetting and collapse of the inner pore (hydrophobic gating) and (2) constriction of the inner pore by tight criss-crossing of the cytoplasmic ends of the S6 α-helical segments. Slo2 channels contain two conserved Leu residues in each of the four S6 segments that line the inner pore region nearest the bottom of the selectivity filter. To evaluate the potential role of these residues in hydrophobic gating, Leu267 and Leu270 in human Slo2.1 were each replaced by 15 different residues. The relative conductance of mutant channels was highly dependent on hydrophilicity and volume of the amino acid substituted for Leu267 and was maximal with L267H. Consistent with their combined role in hydrophobic gating, replacement of both Leu residues with the isosteric but polar residue Asn (L267N/L270N) stabilized channels in a fully open state. In a recent cryo-electron microscopy structure of chicken Slo2.2, the ion permeation pathway of the channel is closed by a constriction of the inner pore formed by criss-crossing of the S6 segments at a conserved Met. Inconsistent with the S6 segment crossing forming the activation gate, replacement of the homologous Met residues in human Slo2.1 or Slo2.2 with the negatively-charged Glu did not induce constitutive channel opening.

Hydrophobic interactions between the S5 segment and the pore helix stabilizes the closed state of Slo2.1 potassium channels.

Under normal physiological conditions, Slo2.1K(+) channels are in a closed state unless activated by an elevation in [Na(+)]i. Fenamates such as niflumic acid also activate Slo2.1. Previous studies suggest that activation of Slo2.1 channels is mediated by a conformational change in the selectivity filter, and not a widening of the aperture formed by the S6 segment bundle crossing as occurs in voltage-gated K(+) channels. It is unclear how binding of Na(+) or fenamates is allosterically linked to opening of the presumed selectivity filter activation gate in Slo2.1. Here we examined the role of the S5 transmembrane segment in the activation of Slo2.1. Channels were heterologously expressed in Xenopus laevis oocytes and whole cell currents measured with the voltage-clamp technique. Ala substitution of five residues located on a single face of the S5 α-helical segment induced constitutive channel activity. Leu-209, predicted to face towards Phe-240 in the pore helix was investigated by further mutagenesis. Mutation of Leu-209 to Glu or Gln induced maximal channel activation as did the combined mutation to Ala of all three hydrophobic S5 residues predicted to be adjacent to Phe-240. Together these results suggest that hydrophobic interactions between residues in S5 and the C-terminal end of the pore helix stabilize Slo2.1 channels in a closed state.

Identification of the Intracellular Na+ Sensor in Slo2.1 Potassium Channels.

Slo2 potassium channels have a very low open probability under normal physiological conditions, but are readily activated in response to an elevated [Na(+)]i (e.g. during ischemia). An intracellular Na(+) coordination motif (DX(R/K)XXH) was previously identified in Kir3.2, Kir3.4, Kir5.1, and Slo2.2 channel subunits. Based loosely on this sequence, we identified five potential Na(+) coordination motifs in the C terminus of the Slo2.1 subunit. The Asp residue in each sequence was substituted with Arg, and single mutant channels were heterologously expressed in Xenopus oocytes. The Na(+) sensitivity of each of the mutant channels was assessed by voltage clamp of oocytes using micropipettes filled with 2 M NaCl. Wild-type channels and four of the mutant Slo2.1 channels were rapidly activated by leakage of NaCl solution into the cytoplasm. D757R Slo2.1 channels were not activated by NaCl, but were activated by the fenamate niflumic acid, confirming their functional expression. In whole cell voltage clamp recordings of HEK293 cells, wild-type but not D757R Slo2.1 channels were activated by a [NaCl]i of 70 mM. Thus, a single Asp residue can account for the sensitivity of Slo2.1 channels to intracellular Na(+). In excised inside-out macropatches of HEK293 cells, activation of wild-type Slo2.1 currents by 3 mM niflumic acid was 14-fold greater than activation achieved by increasing [NaCl]i from 3 to 100 mM. Thus, relative to fenamates, intracellular Na(+) is a poor activator of Slo2.1.

Trace Element Concentrations in Liver of 16 Species of Cetaceans Stranded on Pacific Islands from 1997 through 2013.

The impacts of anthropogenic contaminants on marine ecosystems are a concern worldwide. Anthropogenic activities can enrich trace elements in marine biota to concentrations that may negatively impact organism health. Exposure to elevated concentrations of trace elements is considered a contributing factor in marine mammal population declines. Hawai'i is an increasingly important geographic location for global monitoring, yet trace element concentrations have not been quantified in Hawaiian cetaceans, and there is little trace element data for Pacific cetaceans. This study measured trace elements (Cr, Mn, Cu, Zn, As, Se, Sr, Cd, Sn, Hg, and Pb) in liver of 16 species of cetaceans that stranded on U.S. Pacific Islands from 1997 to 2013, using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) (n = 31), and direct mercury analysis atomic absorption spectrometry (DMA-AAS) (n = 43). Concentration ranges (µg/g wet mass fraction) for non-essential trace elements, such as Cd (0.0031-58.93) and Hg (0.0062-1571.75) were much greater than essential trace elements, such as Mn (0.590-17.31) and Zn (14.72-245.38). Differences were found among age classes in Cu, Zn, Hg, and Se concentrations. The highest concentrations of Se, Cd, Sn, Hg, and Pb were found in one adult female false killer whale (Pseudorca crassidens) at concentrations that are known to affect health in marine mammals. The results of this study establish initial trace element concentration ranges for Pacific cetaceans in the Hawaiian Islands region, provide insights into contaminant exposure of these marine mammals, and contribute to a greater understanding of anthropogenic impacts in the Pacific Ocean.

SLC6 family transporter SNF-10 is required for protease-mediated activation of sperm motility in C. elegans.

Motility of sperm is crucial for their directed migration to the egg. The acquisition and modulation of motility are regulated to ensure that sperm move when and where needed, thereby promoting reproductive success. One specific example of this phenomenon occurs during differentiation of the ameboid sperm of Caenorhabditis elegans as they activate from a round spermatid to a mature, crawling spermatozoon. Sperm activation is regulated by redundant pathways to occur at a specific time and place for each sex. Here, we report the identification of the solute carrier 6 (SLC6) transporter protein SNF-10 as a key regulator of C. elegans sperm activation in response to male protease activation signals. We find that SNF-10 is present in sperm and is required for activation by the male but not by the hermaphrodite. Loss of both snf-10 and a hermaphrodite activation factor render sperm completely insensitive to activation. Using in vitro assays, we find that snf-10 mutant sperm show a specific deficit in response to protease treatment but not to other activators. Prior to activation, SNF-10 is present in the plasma membrane, where it represents a strong candidate to receive signals that lead to subcellular morphogenesis. After activation, it shows polarized localization to the cell body region that is dependent on membrane fusions mediated by the dysferlin FER-1. Our discovery of snf-10 offers insight into the mechanisms differentially employed by the two sexes to accomplish the common goal of producing functional sperm, as well as how the physiology of nematode sperm may be regulated to control motility as it is in mammals.

Concerted all-or-none subunit interactions mediate slow deactivation of human ether-à-go-go-related gene K+ channels.

During the repolarization phase of a cardiac action potential, hERG1 K(+) channels rapidly recover from an inactivated state then slowly deactivate to a closed state. The resulting resurgence of outward current terminates the plateau phase and is thus a key regulator of action potential duration of cardiomyocytes. The intracellular N-terminal domain of the hERG1 subunit is required for slow deactivation of the channel as its removal accelerates deactivation 10-fold. Here we investigate the stoichiometry of hERG1 channel deactivation by characterizing the kinetic properties of concatenated tetramers containing a variable number of wild-type and mutant subunits. Three mutations known to accelerate deactivation were investigated, including R56Q and R4A/R5A in the N terminus and F656I in the S6 transmembrane segment. In all cases, a single mutant subunit induced the same rapid deactivation of a concatenated channel as that observed for homotetrameric mutant channels. We conclude that slow deactivation gating of hERG1 channels involves a concerted, fully cooperative interaction between all four wild-type channel subunits.

Spectral characterization of dissolved organic matter in groundwater to assess mixing with oil-field water near selected oil fields, southern California.

Samples of oil-field water (oil wells, injectate, disposal ponds) and groundwater near selected oil and gas fields in southern California were analyzed for dissolved organic carbon (DOC) concentration and by optical spectroscopic techniques (i.e., absorbance and fluorescence) to assess whether these measurements can be used to distinguish between oil-field water (Oil Field), native groundwater (WGnat), and native groundwater mixed with oil-field water from surface (WGsurf) or subsurface sources (WGsub), and if so whether commonly reported optical measurements can be used as a screening tool to identify such water. Concentrations of DOC were significantly (p < 0.0001) higher (67 to 2934 mg C L-1) in oil-field water compared to native groundwater samples (<5.0 mg C L-1). Individual optical properties varied by water category and frequently overlapped. However, multivariate statistical analysis showed that when evaluated in combination, 10 optical properties were determined by discriminant analysis to be significant (p < 0.05) in distinguishing among water categories. Principal component analysis of those 10 optical properties showed that these properties can be used to successfully distinguish Oil Field samples from WGnat, WGsurf, and WGsub even when mixing fractions are low (approximately 10 %).

Thirdhand vaping exposures are associated with pulmonary and systemic inflammation in a mouse model.

Thirdhand smoke (THS) is the accumulation of secondhand smoke on surfaces that ages with time. THS exposure is a potential health threat to children, partners of smokers, and workers in environments with current or past smoking, and needs further investigation. In this study, we hypothesized that thirdhand Electronic Nicotine Delivery Systems (ENDS) exposures elicit lung and systemic inflammation due to resuspended particulate matter (PM) and inorganic compounds that remain after active vaping has ceased. To test our hypothesis, we exposed C57BL/6J mice to cotton towels contaminated with ENDS aerosols from unflavored vape fluid (6 mg nicotine in 50/50 propylene glycol/vegetable glycerin) for 1h/day, five days/week, for three weeks. We assessed protein levels in serum and bronchoalveolar lavage fluid (BALF) using a multiplex protein assay. The mean ± sd for PM10 and PM2.5 measurements in exposed mouse cages were 8.3 ± 14.0 and 4.6 ± 7.5 µg/m3, compared to 6.1 ± 11.2 and 3.7 ± 6.6 µg/m3 in control cages respectively. Two compounds, 4-methyl-1, 2-dioxolane and 4-methyl-cyclohexanol, were detected in vape fluid and on ENDS-contaminated towels, but not on control towels. Mice exposed to ENDS-contaminated towels had lower levels of serum Il-7 (P = 0.022, n = 7), and higher levels of Il-13 in the BALF (P = 0.006, n = 7) than those exposed to control towels (n = 6). After adjusting for sex and age, Il-7 and Il-13 levels were still associated with thirdhand vaping exposure (P = 0.010 and P = 0.017, respectively). This study provides further evidence that thirdhand ENDS aerosols can contaminate surfaces, and subsequently influence lung and systemic health upon exposure.

Wetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors.

Constructed wetlands are used worldwide to improve water quality while also providing critical wetland habitat. However, wetlands have the potential to negatively impact drinking water quality by exporting dissolved organic carbon (DOC) that upon disinfection can form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs). We used a replicated field-scale study located on organic rich soils in California's Sacramento-San Joaquin Delta to test whether constructed flow-through wetlands which receive water high in DOC that is treated with either iron- or aluminum-based coagulants can improve water quality with respect to DBP formation. Coagulation alone removed DOC (66-77%) and THM (67-70%) precursors, and was even more effective at removing HAA precursors (77-90%). Passage of water through the wetlands increased DOC concentrations (1.5-7.5mgL-1), particularly during the warmer summer months, thereby reversing some of the benefits from coagulant addition. Despite this addition, water exiting the wetlands treated with coagulants had lower DOC and DBP precursor concentrations relative to untreated source water. Benefits of the coagulation-wetland systems were greatest during the winter months (approx. 50-70% reduction in DOC and DBP precursor concentrations) when inflow water DOC concentrations were higher and wetland DOC production was lower. Optical properties suggest DOC in this system is predominantly comprised of high molecular weight, aromatic compounds, likely derived from degraded peat soils.

Social Work Assessment Notes: A Comprehensive Outcomes-Based Hospice Documentation System.

This article describes the development of an integrated psychosocial patient and caregiver assessment and plan of care for hospice social work documentation. A team of hospice social workers developed the Social Work Assessment Notes as a quality improvement project in collaboration with the information technology department. Using the Social Work Assessment Tool as an organizing framework, this comprehensive hospice social work documentation system is designed to integrate assessment, planning, and outcomes measurement. The system was developed to guide the assessment of patients' and caregivers' needs related to end-of-life psychosocial issues, to facilitate collaborative care plan development, and to measure patient- and family-centered outcomes. Goals established with the patient and the caregiver are documented in the plan of care and become the foundation for patient-centered, strengths-based interventions. Likert scales are used to assign numerical severity levels for identified issues and progress made toward goals and to track the outcome of social work interventions across nine psychosocial constructs. The documentation system was developed for use in an electronic health record but can be used for paper charting. Future plans include automated aggregate outcomes measurement to identify the most effective interventions and best practices in end-of-life care.

Associations between Markers of Glucose and Insulin Function and Cognitive Function in Healthy African American Elders.

BACKGROUND: Glucose and insulin are important moderators of cognitive function. African Americans have poorer glycemic control across the glycemic spectrum and are at increased risk for type 2 diabetes and poor cognitive health. It is unclear which glucoregulatory markers predict cognitive function in this at-risk population. The purpose of this study was to examine the association between cognitive function and common markers of glucoregulation in non-diabetic African Americans elders. METHODS: Thirty-four, community-dwelling African Americans, aged 50-75 years completed cognitive testing and blood collection as part of a health screening assessment. Cognitive outcomes were composite scores derived from neuropsychological tests of executive function and verbal memory. Linear regression was used to examine relationships between cognitive composite scores and fasting blood levels of glucose, insulin, and hemoglobin A1C, with adjustments for age, education, body mass index, and antihypertensive medication use. RESULTS: Fasting plasma glucose was negatively associated with executive function (ß=-0.41, p=0.03). There was a trend of an association between fasting plasma glucose and verbal memory (ß=-0.34, p=0.06). Fasting insulin and hemoglobin A1c were not associated with cognitive function. CONCLUSION: High non-diabetic fasting glucose levels were associated with poorer executive function and verbal memory. These results provide preliminary support for proactive glucose control in older African Americans even before glycemic criteria for type 2 diabetes are met. Our findings suggests that high-normal FPG levels may represent an early red-flag to signify increased risk of cognitive impairment or decline.