Endometabolic profiling of pigmented glacier ice algae: the impact of sample processing.

INTRODUCTION: Glacier ice algae, mainly Ancylonema alaskanum and Ancylonema nordenskiöldi, bloom on Greenland Ice Sheet bare ice surfaces. They significantly decrease surface albedo due to their purple-brown pigmentation, thus increasing melt. Little is known about their metabolic adaptation and factors controlling algal growth dynamics and pigment formation. A challenge in obtaining such data is the necessity of melting samples, which delays preservation and introduces bias to metabolomic analysis. There is a need to evaluate the physiological response of algae to melting and establish consistent sample processing strategies for metabolomics of ice microbial communities. OBJECTIVES: To address the impact of sample melting procedure on metabolic characterization and establish a processing and analytical workflow for endometabolic profiling of glacier ice algae. METHODS: We employed untargeted, high-resolution mass spectrometry and tested the effect of sample melt temperature (10, 15, 20 °C) and processing delay (up to 49 h) on the metabolome and lipidome, and complemented this approach with cell counts (FlowCam), photophysiological analysis (PAM) and diversity characterization. RESULTS AND CONCLUSION: We putatively identified 804 metabolites, with glycerolipids, glycerophospholipids and fatty acyls being the most prominent superclasses (> 50% of identified metabolites). Among the polar metabolome, carbohydrates and amino acid-derivatives were the most abundant. We show that 8% of the metabolome is affected by melt duration, with a pronounced decrease in betaine membrane lipids and pigment precursors, and an increase in phospholipids. Controlled fast melting at 10 °C resulted in the highest consistency, and is our recommendation for future supraglacial metabolomics studies.

Herbicides and pesticides synergistically interact at low concentrations in complex mixtures.

Assessing a complex mixture of pesticides at the impacted sites has been challenging for risk assessors for 50 years. The default assumption is that at low concentrations, pesticides interact additively with one another; thus, the risk posed by each component of a complex mixture could be simply added up. The EPA interaction-based hazard index (HIInteraction) modifies this assumption using a binary weight-of-evidence (BINWOE). However, data gaps often preclude HIInteraction use at most sites. This study evaluated these assumptions using the BINWOE to estimate the hazard index (HI) of select pesticide mixtures. The lack of in vivo binary interaction data led us to use a cell line, SH-SY5Y, to obtain the data necessary for the BINWOE approach. In the risk assessment, we considered the most active exposure scenario inhaling a mixture of volatile pesticides from contaminated soil and groundwater. The potential interactions between pesticides in 15 binary mixtures were investigated using the MTT assay in SH-SY5Y cells. Our findings showed that 60% of the binary mixtures elicited synergism (in at least one concentration), 27% displayed antagonism, and 13% showed additive effects in SH-SY5Y cells. Combining human safety data with in vitro interaction data indicated that adults and toddlers were at the highest risk when considering industrial and commercial land use, respectively, compared to other subpopulations. Incorporating interaction data into the risk assessment either increased the risk by up to 20% or decreased the risk by 2%, depending on the mixture. Our results demonstrate the predominant synergistic interactions, even at low concentrations, altered risk characterization at the complex operating site. Most concerning, organochlorine pesticides with the same mechanism of action did not follow dose additivity when evaluated by SH-SY5Y cell lines. Based on our observations, we caution that current HI methods based on additivity assumptions may underestimate the risk of organochlorine mixtures.

Boomerang Modification of the Septal Extension Graft: Graft Design and Functional Outcomes.

Background: A "boomerang" graft is an end-to-end caudal septal extension graft (SEG) that conforms to the geometry of the anterior septal angle, and avoids septal overlap, unlike a side-to-side SEG. Objective: To compare breathing improvements in rhinoplasty patients receiving boomerang SEGs and patients receiving side-to-side SEGs. Methods: Retrospective cohort analysis of patients undergoing rhinoplasty with either end-to-end boomerang SEG or a side-to-side SEG. Functional outcomes were assessed through the Nasal Obstruction Symptom Evaluation (NOSE) survey. Results: The boomerang SEG cohort had a mean age of 34 years and were 68% female compared with 38 years and 67% female in the side-to-side SEG cohort (p > 0.05). The cohorts did not differ in the proportion of the lateral crural tensioning, spreader graft placement, or history of rhinoplasty. The boomerang cohort demonstrated a 67% reduction in NOSE scores compared with a 70% reduction among the side-to-side SEG cohort (p = 0.14). Men undergoing boomerang graft placement reported significantly less postoperative functional improvement than men undergoing placement of a side-to-side SEG (62% vs. 77%, p = 0.01). Conclusion: Use of a boomerang graft is not likely to negatively affect rhinoplasty functional outcomes when compared with a side-to-side SEG.

Impaired memory in Sprague-Dawley rats exposed to complex groundwater mixtures of contaminants is associated with reduced cranial blood flow and hippocampal neurotoxicity.

Exposure to industrial contaminants has been implicated in neurobehavioral toxicity in humans. To explore this potential risk, we investigated the neurotoxic effects of oral exposure to a complex groundwater mixture containing petroleum hydrocarbons, pesticides, heavy metals, and unknown parent and breakdown products using male and female Sprague Dawley rats. Rats were randomly divided into six groups and orally exposed daily via drinking water to: (i) tap water, (ii) 10 % v/v low impact groundwater, and (iii) 0.01 %, 0.1 %, 1 %, and 10 % high-impact groundwater for 60 days. Medium- and long-term memory (measured using the novel object recognition task) were impaired. However, no gross motor or coordination deficits were observed by the end of the study period (rotarod test). Doppler ultrasound of the middle cerebral and common carotid arteries was performed to examine the hemodynamic changes. The common carotid blood flow decreased in the groundwater-exposed rats compared to that in the control. However, no significant differences in cerebral blood velocity were observed between the exposed and control groups. A significant reduction in hippocampal serotonin levels was observed in groundwater-exposed rats relative to that in the control group. Collectively, these results indicate that impaired recognition memory in rats exposed to groundwater is accompanied by reduced cranial blood flow and hippocampal neurotoxicity, characterized by altered serotonergic signalling. The levels of detected contaminants known to cause neural or vascular damage were of magnitudes lower than the concentrations of contaminants found in the groundwater mixture, meaning the culprit chemical identity remains unknown. This study emphasizes the need to use whole mixture in exposures when dealing with complex contaminated sites rather than the use of individual compounds.