Saccharides enhance iron bioavailability to Southern Ocean phytoplankton.

Iron limits primary productivity in vast regions of the ocean. Given that marine phytoplankton contribute up to 40% of global biological carbon fixation, it is important to understand what parameters control the availability of iron (iron bioavailability) to these organisms. Most studies on iron bioavailability have focused on the role of siderophores; however, eukaryotic phytoplankton do not produce or release siderophores. Here, we report on the pivotal role of saccharides--which may act like an organic ligand--in enhancing iron bioavailability to a Southern Ocean cultured diatom, a prymnesiophyte, as well as to natural populations of eukaryotic phytoplankton. Addition of a monosaccharide (>2 nM of glucuronic acid, GLU) to natural planktonic assemblages from both the polar front and subantarctic zones resulted in an increase in iron bioavailability for eukaryotic phytoplankton, relative to bacterioplankton. The enhanced iron bioavailability observed for several groups of eukaryotic phytoplankton (i.e., cultured and natural populations) using three saccharides, suggests it is a common phenomenon. Increased iron bioavailability resulted from the combination of saccharides forming highly bioavailable organic associations with iron and increasing iron solubility, mainly as colloidal iron. As saccharides are ubiquitous, present at nanomolar to micromolar concentrations, and produced by biota in surface waters, they also satisfy the prerequisites to be important constituents of the poorly defined "ligand soup," known to weakly bind iron. Our findings point to an additional type of organic ligand, controlling iron bioavailability to eukaryotic phytoplankton--a key unknown in iron biogeochemistry.

Non-UV light influences the degradation rate of crop protection products.

Crop protection products (CPPs) are subject to strict regulatory evaluation, including laboratory and field trials, prior to approval for commercial use. Laboratory tests lack environmental realism, while field trials are difficult to control. Addition of environmental complexity to laboratory systems is therefore desirable to mimic a field environment more effectively. We investigated the effect of non-UV light on the degradation of eight CPPs (chlorotoluron, prometryn, cinosulfuron, imidacloprid, lufenuron, propiconazole, fludioxonil, and benzovindiflupyr) by addition of non-UV light to standard OECD 307 guidelines. Time taken for 50% degradation of benzovindiflupyr was halved from 373 to 183 days with the inclusion of light. Similarly, time taken for 90% degradation of chlorotoluron decreased from 79 to 35 days under light conditions. Significant reductions in extractable parent compound occurred under light conditions for prometryn (4%), imidacloprid (8%), and fludioxonil (24%) compared to dark controls. However, a significantly slower rate of cinosulfuron (14%) transformation was observed under light compared to dark conditions. Under light conditions, nonextractable residues were significantly higher for seven of the CPPs. Soil biological and chemical analyses suggest that light stimulates phototroph growth, which may directly and/or indirectly impact CPP degradation rates. The results of this study strongly suggest that light is an important parameter affecting CPP degradation, and inclusion of light into regulatory studies may enhance their environmental realism.

The body as a living bioreactor: a feasibility study of pedicle flaps for tracheal transplantation.

Reconstruction of long-segment tracheal stenosis remains problematic. Ex vivo transplantation of stem cell-derived tracheas has been established in humans using external tissue bioreactors. These bioreactors, however, are not widely accessible. Thus, we are developing a rotational flap-based "internal bioreactor" to allow in vivo stem cell engraftment in a pre-vascularized recipient bed. This muscle will also then serve as a carrier for the transplanted trachea during rotation into position for airway reconstruction. Herein, we present a study investigating the feasibility of two pedicle muscle flaps for implantation and subsequent tracheal transplantation. Trapezius and latissimus flaps were raised using established surgical techniques. The length and width of each flap, along with the distance from the pedicle takeoff to the trachea, were measured. The overall ability of the flaps to reach the trachea was assessed. Twelve flaps were raised in 5 fresh adult human cadavers. For the trapezius flap, averages were: flap length of 16.4 cm, flap width of 5.95 cm at the tip, and distance from the pedicle takeoff to the trachea of 11.1 cm. For the latissimus dorsi flap, averages were: flap length of 35.4 cm, flap width of 7.25 cm at the tip, and distance from the pedicle takeoff to the trachea of 27.3 cm. All flaps showed sufficient durability and rotational ability. Our results show that both trapezius and latissimus dorsi flaps can be transposed into the neck to allow tension-free closure of tracheal defects. For cervical tracheal transplantation, both flaps are equally adequate. We believe that trapezius and latissimus dorsi muscle flaps are potential tracheal implantation beds in terms of vascular supply, durability, and rotational ability.

The Impact of Disturbed Soil Structure on the Degradation of 2 Fungicides Under Constant and Variable Moisture.

Degradation of agrochemicals in soil is frequently faster under field conditions than in laboratory studies. Field studies are carried out on relatively undisturbed soil, whereas laboratory studies typically use sieved soil, which can have a significant impact on the physical and microbial nature of the soil and may contribute to differences in degradation between laboratory and field studies. A laboratory study was therefore conducted to determine the importance of soil structure and variable soil moisture on the degradation of 2 fungicides (azoxystrobin and paclobutrazol) that show significant differences between laboratory and field degradation rates in regulatory studies. Degradation rates were measured in undisturbed cores of a sandy clay loam soil (under constant or variable moisture contents) and in sieved soil. For azoxystrobin, degradation rates under all conditions were similar (median degradation time [DegT50] 34-37 d). However, for paclobutrazol, degradation was significantly faster in undisturbed cores (DegT50 255 d in sieved soil and 63 d in undisturbed cores). Varying the moisture content did not further enhance degradation of either fungicide. Further examination into the impact of soil structure on paclobutrazol degradation, comparing undisturbed and sieved/repacked cores, revealed that the impact of sieving could not be mitigated by repacking the soil to a realistic bulk density. Examination of fungal and bacterial community structure using automated ribosomal spacer analysis showed significant initial differences between sieved/repacked and intact soil cores, although such differences were reduced at the end of the study (70 d). The present study demonstrates that disruption of soil structure significantly impacts microbial community structure, and for some compounds this may explain the differences between laboratory and field degradation rates. Environ Toxicol Chem 2021;40:2715-2725. © 2021 SETAC.

Implementation and evaluation of a near-peer-facilitated medical ethics curriculum for first-year medical students: a pilot study.

INTRODUCTION: The primary objectives of this study were to implement a novel near-peer-facilitated case-based medical ethics curriculum intended for the audience of a large cohort of first-year medical students (n = 193) and to objectively evaluate the immediate efficacy of the curriculum based on pre- and post-session survey responses to ethical quandaries. METHODS: Two near-peer-facilitated medical ethics case discussion sessions were included in the first-year curriculum during the 2017-2018 academic year. The sessions were designed and led by second-year medical student facilitators under the direction of a faculty mentor and were presented as a year-long curricular thread. First-year students were asked to complete pre- and post-session surveys with ethical questions relevant to each case and session. Students were additionally asked to measure the contribution of discussion sessions to their development as a future physician. RESULTS: Post-session survey results showed that students had a better understanding of specific ethical issues immediately following discussion sessions (p<0.0001). Over three-quarters of students indicated that the near-peer-led medical ethics case discussions contributed somewhat or very much to their development as a future physician. Anecdotal feedback from second-year medical students also suggested that their involvement as facilitators was beneficial to their educational development. CONCLUSION: Near-peer-facilitated case discussions were an effective strategy for teaching medical ethics to first-year medical students with demonstrated objective improvements in ethical decision-making. Additionally, near-peer discussions of ethical cases and principles with first-year medical students aided in subjective measures of professional development.

Microbial signature lipid profiling and exopolysaccharides: experiences initiated with Professor David C White and transported to Tasmania, Australia.

Developments and applications with signature lipid and exopolysaccharide (EPS) methodologies covering a thirty year period in the DC White laboratories at Florida State University and the University of Tennessee at Knoxville are illustrated. These powerful techniques were used to gain new insight into microbial communities, not obtainable by classical approaches. Selected case examples are highlighted and include: use of a specific dimethyl disulphide (DMDS) derivitization procedure with monounsaturated fatty acids (MUFA) to precisely determine double bond position and geometry; application of the DMDS procedure in taxonomic and environmental studies including the degradation of pollutant halogenated hydrocarbons in groundwater and subsurface aquifers; exploiting the ubiquitous nature of uronic acids in microbial EPS to quantify these exopolymers in complex environmental samples; development of rapid and non-destructive approaches including FT-IR to follow biofilm formation in a unique manner not possible with other approaches. The foundations laid in the DC White laboratories have seen a wide suite of applications in modern microbial ecology and associated fields. The training of young scientists by DC White will also ensure that his unique approach and quest for new and or novel methodologies for use in environmental microbiology will continue.

Creeping in the night: What might ecologists be missing?

Wildlife activity patterns tend to be defined by terms such as diurnal and nocturnal that might not fully depict the complexity of a species' life history strategy and behavior in a given system. These activity pattern categories often influence the methodological approaches employed, including the temporal period of study (daylight or nighttime). We evaluated banded mongoose (Mungos mungo) behavior in Northern Botswana through the use of remote sensing cameras at active den sites in order to characterize early morning behavior for this diurnal species. Our approach, however, provided the facility to capture unexpected nocturnal activity in a species that had otherwise only been studied during daylight hours. Camera traps were deployed for 215 trap days (24 hour data capture period) at den sites, capturing 5,472 photos over all events. Nocturnal activity was identified in 3% of trap days at study den sites with both vigilant and non-vigilant nocturnal behaviors identified. While vigilant behaviors involved troop fleeing responses, observations of non-vigilant behaviors suggest nonresident mongoose may investigate den sites of other troops during nocturnal time periods. There was no association between the occurrence of nocturnal activity and lunar phase (Fisher's exact test, n = 215, p = 0.638) and thus, increased moonlight was not identified as a factor influencing nocturnal behavior. The drivers and fitness consequences of these nocturnal activities remain uncertain and present intriguing areas for future research. Our findings highlight the need for ecological studies to more explicitly address and evaluate the potential for temporal variability in activity periods. Modifying our approach and embracing variation in wildlife activity patterns might provide new insights into the interaction between ecological phenomenon and species biology that spans the diurnal-nocturnal spectrum.

Quantifying soil surface photolysis under conditions simulating water movement in the field: a new laboratory test design.

Soil surface photolysis can be a significant dissipation pathway for agrochemicals under field conditions, although it is assumed that such degradation ceases once the agrochemical is transported away from the surface following rainfall or irrigation and subsequent drainage of soil porewater. However, as both downward and upward water movements occur under field conditions, relatively mobile compounds may return to the surface, prolonging exposure to ultraviolet light and increasing the potential for degradation by photolysis. To test this hypothesis, a novel experimental system was used to quantify the contribution of photolysis to the overall dissipation of a new herbicide, bicyclopyrone, under conditions that mimicked field studies more closely than the standard laboratory test guidance. Soil cores were taken from 3 US field study sites, and the surfaces were treated with [(14) C]-bicyclopyrone. The radioactivity was redistributed throughout the cores using a simulated rainfall event, following which the cores were incubated under a xenon-arc lamp with continuous provision of moisture from below and a wind simulator to induce evaporation. After only 2 d, most of the test compound had returned to the soil surface. Significantly more degradation was observed in the irradiated samples than in a parallel dark control sample. Degradation rates were very similar to those observed in both the thin layer photolysis study and the field dissipation studies and significantly faster than in the soil metabolism studies conducted in the dark. Thus, for highly soluble, mobile agrochemicals, such as bicyclopyrone, photolysis is not terminated permanently by rainfall or irrigation but can resume following transport to the surface in evaporating water.

Comparison of Thraustochytrids Aurantiochytrium sp., Schizochytrium sp., Thraustochytrium sp., and Ulkenia sp. for production of biodiesel, long-chain omega-3 oils, and exopolysaccharide.

Heterotrophic growth of thraustochytrids has potential in coproducing biodiesel for transportation, as well as producing a feedstock for omega-3 long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid (DHA) for use in nutraceuticals. In this study, we compared eight new endemic Australian thraustochytrid strains from the genera Aurantiochytrium, Schizochytrium, Thraustochytrium, and Ulkenia for the synthesis of exopolysaccharide (EPS), in addition to biodiesel and LC-PUFA. Aurantiochytrium sp. strains readily utilized glucose for biomass production, and increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased biomass yield by an average factor of 1.7. Ulkenia sp. strain TC 010 and Thraustochytrium sp. strain TC 033 did not utilize glucose, while Schizochytrium sp. strain TC 002 utilized less than half the glucose available by day 14, and Thraustochytrium sp. strain TC 004 utilized glucose at 4 % w/v but not 2 % w/v of the culture suggesting a threshold requirement between these values. Across all strains, increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased total fatty acid methyl ester content by an average factor of 1.9. Despite an increasing literature demonstrating the capacity of thraustochytrids for DHA synthesis, the production of EPS from these organisms is not well documented. A broad range of EPS yields was observed. The maximum yield of EPS was observed for Schizochytrium sp. strain TC 002 (299 mg/L). High biomass-producing strains that also have high lipid and high EPS yield may be better candidates for commercial production of biofuels and other coproducts.

Are physical activity and nutrition indicators of the checklist of health promotion environments at worksites (CHEW) associated with employee obesity among hotel workers?

OBJECTIVE: Worksites provide opportunities to reach more than 60% of adults in the United States, including populations diverse in race, ethnicity, gender, age, occupation, income, and health status. Employers that provide worksite weight management interventions have the potential to reduce sick leave, health care costs, and workers compensation costs, and increase employee morale and worker efficiency. Hotels specifically, represent a broad cross-section of job categories, and most hotels are staffed and operated similarly around the world. However, from our literature review, there have been no investigations of the association between the hotel environment and employees' obesity. METHODS: For this study, we tested the relationship between environmental factors in hotels and employees' body mass index (BMI). RESULTS: Overall no substantial correlations were found on any environmental variable. However, hotel size affected some relationships. Higher BMI was related to greater number of stairs, stair facilitation, and the healthy eating facilitation variables (excluding nutrition signs or posters) in medium sized hotels. Lower BMI was found with greater stair facilitation in small hotels; and with greater number of physical activity (PA) signs, lunch room nutrition signs, and hotel nutrition signs in large hotels. Unionized status affected only two environmental variables. For unionized hotels, BMI was negatively correlated with PA signs and positively correlated with the healthy eating facilitation. CONCLUSIONS: No logical pattern of association was found between workplace environmental factors and hotel employee BMI levels. Further research should investigate the interaction of the size and structure of the workplace with the impact of environmental efforts to reduce overweight and obesity.

L-type Ca2+ channel function in the avian embryonic heart after cardiac neural crest ablation.

In avian and mammalian embryos, surgical ablation or severely reduced migration of the cardiac neural crest leads to a failure of outflow tract septation known as persistent truncus arteriosus (PTA) and leads to embryo lethality due partly to impaired excitation-contraction coupling stemming primarily from a reduction in the L-type Ca(2+) current (I(Ca),(L)). Decreased I(Ca,L) occurs without a corresponding reduction in the alpha(1)-subunit of the Ca(2+) channel. We hypothesize that decreased I(Ca),(L) is due to reduced function at the single channel level. The cell-attached patch clamp with Na(+) as the charge carrier was used to examine single Ca(2+) channel activity in myocytes from normal hearts from sham-operated embryos and from hearts diagnosed with PTA at embryonic days (ED) 11 and 15 after laser ablation of the cardiac neural crest. In normal hearts, the number of single channel events per 200-ms depolarization and the mean open channel probability (P(o)) was 1.89 +/- 0.17 and 0.067 +/- 0.008 for ED11 and 1.14 +/- 0.17 and 0.044 +/- 0.005 for ED15, respectively. These values represent a normal reduction in channel function and I(Ca),(L) observed with development. However, the number of single channel events was significantly reduced in hearts with PTA at both ED11 and ED15 (71% and 47%, respectively) with a corresponding reduction in P(o) (75% and 43%). The open time frequency histograms were best fitted by single exponentials with similar decay constants (tau approximately or equal 4.5 ms) except for the sham operated at ED15 (tau = 3.4 ms). These results indicate that the cardiac neural crest influences the development of myocardial Ca(2+) channels.

Olleya marilimosa gen. nov., sp. nov., an exopolysaccharide-producing marine bacterium from the family Flavobacteriaceae, isolated from the Southern Ocean.

A Gram-negative, aerobic, gliding, orange-yellow marine bacterium was isolated from particulate material sampled from the Southern Ocean. This strain produced an exopolysaccharide in liquid culture. 16S rRNA gene sequence analysis showed that this isolate was a member of the family Flavobacteriaceae, but represented a separate lineage. Major whole-cell fatty acids included i15:1omega10c, i15:0, beta-OH i15:0, a15:1omega10c, 15:0 and alpha-OH i15:0. The G+C content of the DNA was 49 mol%. Based on phylogenetic, phenotypic, chemotaxonomic and genotypic analyses, this bacterium was placed in a novel taxon as Olleya marilimosa gen. nov., sp. nov. with type strain CAM030(T) (=ACAM 1065(T)=CIP 108537(T)).

Effects of incubation temperature on growth and production of exopolysaccharides by an antarctic sea ice bacterium grown in batch culture.

The sea ice microbial community plays a key role in the productivity of the Southern Ocean. Exopolysaccharide (EPS) is a major component of the exopolymer secreted by many marine bacteria to enhance survival and is abundant in sea ice brine channels, but little is known about its function there. This study investigated the effects of temperature on EPS production in batch culture by CAM025, a marine bacterium isolated from sea ice sampled from the Southern Ocean. Previous studies have shown that CAM025 is a member of the genus Pseudoalteromonas and therefore belongs to a group found to be abundant in sea ice by culture-dependent and -independent techniques. Batch cultures were grown at -2 degrees C, 10 degrees C, and 20 degrees C, and cell number, optical density, pH, glucose concentration, and viscosity were monitored. The yield of EPS at -2 degrees C and 10 degrees C was 30 times higher than at 20 degrees C, which is the optimum growth temperature for many psychrotolerant strains. EPS may have a cryoprotective role in brine channels of sea ice, where extremes of high salinity and low temperature impose pressures on microbial growth and survival. The EPS produced at -2 degrees C and 10 degrees C had a higher uronic acid content than that produced at 20 degrees C. The availability of iron as a trace metal is of critical importance in the Southern Ocean, where it is known to limit primary production. EPS from strain CAM025 is polyanionic and may bind dissolved cations such at trace metals, and therefore the presence of bacterial EPS in the Antarctic marine environment may have important ecological implications.

Chemical characterization of exopolysaccharides from Antarctic marine bacteria.

Exopolysaccharides (EPS) may have an important role in the Antarctic marine environment, possibly acting as ligands for trace metal nutrients such as iron or providing cryoprotection for growth at low temperature and high salinity. Ten bacterial strains, isolated from Southern Ocean particulate material or from sea ice, were characterized. Whole cell fatty acid profiles and 16S rRNA gene sequences showed that the isolates included representatives of the genera Pseudoalteromonas, Shewanella, Polaribacter, and Flavobacterium as well as one strain, which constituted a new bacterial genus in the family Flavobacteriaceae. The isolates are, therefore, members of the "Gammaproteobacteria" and Cytophaga-Flexibacter-Bacteroides, the taxonomic groups that have been shown to dominate polar sea ice and seawater microbial communities. Exopolysaccharides produced by Antarctic isolates were characterized. Chemical composition and molecular weight data revealed that these EPS were very diverse, even among six closely related Pseudoalteromonas isolates. Most of the EPS contained charged uronic acid residues; several also contained sulfate groups. Some strain produced unusually large polymers (molecular weight up to 5.7 MDa) including one strain in which EPS synthesis is stimulated by low temperature. This study represents a first step in the understanding of the role of bacterial EPS in the Antarctic marine environment.

Algoriphagus ratkowskyi gen. nov., sp. nov., Brumimicrobium glaciale gen. nov., sp. nov., Cryomorpha ignava gen. nov., sp. nov. and Crocinitomix catalasitica gen. nov., sp. nov., novel flavobacteria isolated from various polar habitats.

Several cold-adapted strains isolated from a variety of algal-rich Antarctic and Southern Ocean samples formed three distinct groups within the class Flavobacteria, phylogenetically distant from other cultivated species. The first taxon, designated Algoriphagus ratkowskyi gen. nov., sp. nov., was isolated from sea ice and from saline lake cyanobacterial mats and includes non-motile, strictly aerobic, saccharolytic rod-like or serpentine strains that were most closely related to the genus Cyclobacterium according to 16S rDNA sequence analysis (sequence similarity 0.85). The second taxon, designated Brumimicrobium glaciale gen. nov., sp. nov., isolated from sea ice and from continental shelf sediment, formed gliding, rod-like cells that were facultatively anaerobic with a fermentative metabolism. The third taxon, designated Cryomorpha ignava gen. nov., sp. nov., isolated from Southern Ocean particulates and from quartz stone subliths, included strictly aerobic, pleomorphic rod-like cells. Brumimicrobium glaciale and Cryomorpha ignava were most closely allied with 'Microscilla aggregans var. catalatica', which, on the basis of its distinctive taxonomic traits, is also proposed as a new genus and species, Crocinitomix catalasitica gen. nov., sp. nov. It is proposed that the three genera Brumimicrobium, Cryomorpha and Crocinitomix belong to a new family, Cryomorphaceae fam. nov. (type genus Cryomorpha), as they possess generally similar morphological and ecophysiological characteristics and form a common and distinct clade within class FLAVOBACTERIA: