Laboratory Exposure Research Articles

Implementationof a Biosafety Software Pop-up after Two Brucella Laboratory Exposures

IntroductionBrucellosis is rare in non-endemic countries where it mainly occurs as an imported or travel-related disease. In rare cases, Brucella species (spp.) are present in clinical specimens processed by clinical microbiology laboratories. These pathogens pose a risk to laboratory technicians, due to the high virulence, a low-infectious dose and ease of aerosol formation. Due to the low incidence in non-endemic countries, clinical samples are routinely processed on laboratory benches outside laminar flow cabinets. Recently, we have had three unexpected cases in which Brucella spp. were cultured at our clinical microbiology laboratory: one Brucella canis case and two Brucella melitenis cases. The B. canis and the first B. melitenis cases prompted the introduction of a biosafety software pop-up, which is presented in this paper. MethodsHere, we describe the two B. melitensis cases and the introduction of a biosafety pop-up. The software pop-up parameters are a time-to-positivity (TTP) of more than 48 hours, in an aerobic blood culture bottle, and a Gram stain appearance as Gram-negative bacteria. The software pop-up warns the technician through the laboratory information system (LIS) to further process the specimen in the Class 2 biological safety cabinet. To assess the number of false-positive pop-ups we can expect and resulting additional workload, we retrospectively analyzed laboratory data from the last seven years. ResultsThe biosafety pop-up prevented laboratory exposure in the second B. melitensis case. Based on the retrospective analysis of laboratory data, we estimated the resulting additional workload of implementation of the biosafety pop-up to be less than one blood culture bottle per week on average to be processed in a Class 2 biological safety cabinet. ConclusionOur experience demonstrates that implementation of the biosafety software pop-up can reduce the risk of laboratory exposure to Brucella spp. This intervention provides a feasible approach even in a setting where Brucella spp. are normally only encountered every few years.

The Evolving Global Epidemiology of Human Melioidosis: A Narrative Review

Endemic in over 45 countries globally, recent reports of locally acquired melioidosis in novel geographical areas, such as the Southern US, have highlighted the expanding geographical range of Burkholderia pseudomallei. Climate change and severe weather events have been linked to an increase in cases of melioidosis, which follows environmental exposure to the bacterium. Healthcare professionals should be aware of the possibility of the disease, with its diverse and often delayed presentations, even in areas not previously known to have risk. Over 200 cases of travel-associated melioidosis have been reported in the literature, highlighting the need to consider this disease in non-endemic areas, as diagnostic delays of up to 18 months have been identified. The review updates the global epidemiology of melioidosis, focusing on new geographical areas where cases have been diagnosed and imported cases, unusual clinical presentations and co-infections, and less frequent modes of transmission (laboratory exposures and the risk of acquisition due to imported infected animals and contaminated products).

LC3 cementitious binder incorporating microencapsulated phase change materials for self-defrosting traffic surfaces

Exposed surfaces of bridge decks, viaducts and pavements incur ice formation and accumulation of snow in cold seasons, which threatens traffic safety. Mitigating this problem using traditional methods such as deicing salts have caused ecosystem damage and inflicted substantial reinforcement corrosion and surface scaling to bridge decks and pavements, thus compromising their service life and causing colossal economic loss. This paper presents an alternative solution to overcome this problem through the development of a sustainable LC3 cementitious material incorporating micro-encapsulated phase change material (MEPCM) with low phase transition temperature to delay the surface temperature drop and mitigate snow accumulation and ice formation. MEPCM was incorporated in the cementitious matrix at 0 %, 10 % and 20 % by binder mass. Paste and mortar mixtures were prepared to investigate the microstructural, mechanical, physical, and thermal properties. Test results showed that incorporating MEPCM in the LC3 matrix achieved adequate compressive strength. Thermal simulations and visual observations conducted on mortar samples in the laboratory and outdoor exposure showed that MEPCM can effectively regulate the surface temperature of the LC3 matrix and mitigate temperature drops as well as snow accumulation. Analysis of temperature data in the 2023–2024 winter season of Hamilton, Ontario, Canada indicated that the MEPCM incorporated in mortar samples could effectively regulate 40 % of the total days considered and mitigate surface ice formation and snow accumulation, which provides both economic and environmental benefits.

Photophysiological and Oxidative Responses of the Symbiotic Estuarine Anemone Anthopleura hermaphroditica to the Impact of UV Radiation and Salinity: Field and Laboratory Approaches.

The estuarine anemone Anthopleura hermaphroditica and its symbiont Philozoon anthopleurum are continuously exposed to intense fluctuations in solar radiation and salinity owing to tidal changes. The aim of this study was to evaluate the effects of the tidal cycle, solar radiation, and salinity fluctuations on the photosynthetic and cellular responses (lipid peroxidation, total phenolic compounds, and antioxidant activity) of the symbiont complex over a 24 h period in the Quempillén River Estuary. Additionally, laboratory experiments were conducted to determine the specific photobiological responses to photosynthetically active radiation (PAR), ultraviolet radiation (UVR), and salinity. Our field results showed that the photosynthetic parameters of the symbiont complex decreased with increasing ambient radiation; however, no relationship was observed with changes in salinity. Increased peroxidative damage, total phenolic compound levels, and antioxidant activity were mainly related to increased UVR and, to a lesser extent, PAR. During the dark period, only PAR-exposed organisms returned to the basal levels of photosynthesis and cell damage. Laboratory exposure confirmed the deleterious effects of UVR on the photosynthetic response. The present study suggests that the ability of A. hermaphroditica to acclimate to natural radiation stress is mediated by the concerted action of various physiological mechanisms that occur at different times of the day, under varying levels of environmental stress.

Multiple Biomarker Responses in Aegla castro Exposed to Copper: A Laboratory Approach.

Although some biomarkers have already been determined in aeglids collected in the field, data from laboratory exposures are scarce. To our knowledge, no studies have investigated oxidative stress biomarkers in aeglids exposed to metals in the laboratory, or performed hemocyte counts and the comet assay using gill and hepatopancreas of aeglids. Thus, we investigated the effects of acute Cu exposure on intermolt males of Aegla castro, collected from a reference stream, acclimated for 6days in the laboratory, and then exposed to 11μgL-1 of dissolved Cu (Cu 11) or only to water (CTR), for 24h. Gill and hepatopancreas samples were used to determine Cu accumulation, DNA damage, and metallothionein content (MT), while hemolymph samples were used to determine Cu accumulation, DNA damage, and hemocyte counts. Muscle samples were used to determine Cu accumulation and acetylcholinesterase activity (AChE). Non-protein thiol content (NPSH), catalase (CAT), glutathione S-transferase activities (GST), lipoperoxidation (LPO), and protein carbonylation content (PCC) were measured only in the hepatopancreas. Aegla castro exposed to Cu accumulated this metal in gills and activated detoxification mechanisms, through increased MT content in the gill, and showed an immune response, evidenced by an increase in hyaline hemocytes. Therefore, gill and hemocytes appear to have a protective role in preventing the transport and bioavailability of Cu through the body. On the other hand, we observed a decrease in MT content in the hepatopancreas of crabs exposed to Cu, suggesting the excretion of MT in association with Cu bound to the sulfhydryl groups of this protein.

Developing analytical skills for biomarkers of exposure in a university laboratory for research, health management and risk assessment in Uruguay

Developing analytical skills for biomarkers of exposure in a university laboratory for research, health management and risk assessment in Uruguay

Uronium peptide coupling agents: Another case of occupational airborne allergic sensitization induced by HBTU.

Uronium peptide coupling agents (HBTU, HATU, and HCTU) create a special hazard as they are immune sensitizers. Few reported cases are mentioned in the literature; despite that, it is important to raise the awareness on the subject and to highlight the risk and potential symptoms that could occur to those who directly work in contact with uronium peptide coupling agents, as well as to the safety deputies in the universities and industries. Based on a personal experience, the health impact of laboratory exposure to HBTU is described, and the insights gained from the experience are developed. A skin irritation reaction and allergy symptoms induced by HBTU exposure are shown here as well as the rate of worsening of symptoms since the first allergic reaction. Recommendations for handling coupling agents more safely in the research laboratory will also be given, and a casuistry of the matter to help other lab-users to recognize, assess, minimize, prepare for emergencies (RAMP) process.

Approach and Conquer: Optimizing Fear Extinction by Adding Approach?

Exposure treatment involves systematic confrontation with fear-inducing stimuli, effectively reducing fear and anxiety. However, a significant number of clients still experience a return of fear (ROF) after treatment. This study investigates whether incorporating an approach component during fear extinction, a laboratory exposure analog, could mitigate this return of fear. Furthermore, we explored the underlying mechanisms by drawing on predictions from the inhibitory learning theory and the reflective-impulsive model of behavior. In a within-subjects design, we compared instructed active approach of a stimulus during extinction to more passive non-avoidance. Contrary to expectations, our findings revealed that performing approach behavior during extinction did not reduce ROF when compared to non-avoidance. Furthermore, valence and action tendencies, which were potential mechanisms based on the reflective-impulsive model of behavior, remained unaltered. Still, a noteworthy discovery emerged in the form of increased threat expectancies for the approached stimulus during extinction, suggesting a heightened level of expectancy violation, as predicted on the basis of the inhibitory learning theory. These findings offer valuable insights into the intricate relationship between approach behavior, ROF, and underlying mechanisms, highlighting the need for further research to assess the potential benefits of emphasizing approach in exposure treatment.

Exposure to PFAS contaminated urban wetland water causes similar metabolic alterations to laboratory-based exposures in the freshwater amphipod Austrochiltonia subtenuis

Assessing the harm caused by pollutants in urban ecosystems remains a significant challenge. Traditional ecotoxicological endpoints are often not sensitive enough to detect the effects of toxicants at environmentally relevant concentrations (≤ng/L). A potential solution is using molecular biology methods to look at small biochemical changes caused by exposure to ng/L concentrations of contaminants. This has been tested in the lab but not conclusively demonstrated in the field. We exposed the freshwater amphipod (Austrochiltonia subtenuis) to water from an urban wetland containing known concentrations of per-and polyfluoroalkyl substances (as well as very low concentrations of pesticides) for 14 days and analyzed their metabolite profiles. Mannose, Myo-inositol, and Isopropyl propionate were found to change in PFAS exposed amphipods, a similar response to that previously observed in laboratory exposures to the same PFAS, but not pesticides. The results give a better understanding of PFAS toxicity at environmentally relevant concentrations and conditions.

Integrating Transcriptomics and Proteomics to Characterize the Intestinal Responses to Cadmium Exposure Using a Piglet Model.

Cadmium (Cd) is a heavy metal element with a wide range of hazards and severe biotoxicity. Since Cd can be easily accumulated in the edible parts of plants, the exposure of humans to Cd is mainly through the intake of Cd-contaminated food. However, the intestinal responses to Cd exposure are not completely characterized. Herein, we simulated laboratory and environmental Cd exposure by feeding the piglets with CdCl2-added rice and Cd-contaminated rice (Cdcr) contained diet, as piglets show anatomical and physiological similarities to humans. Subsequent analysis of the metal element concentrations showed that exposure to the two types of Cd significantly increased Cd levels in piglets. After verifying the expression of major Cd transporters by Western blots, multi-omics further expanded the possible transporters of Cd and found Cd exposure causes wide alterations in the metabolism of piglets. Of significance, CdCl2 and Cdcr exhibited different body distribution and metabolic rewiring, and Cdcr had stronger carcinogenic and diabetes-inducing potential. Together, our results indicate that CdCl2 had a significant difference compared with Cdcr, which has important implications for a more intense study of Cd toxicity.

Comparative susceptibility of adult house fly (Diptera: Muscidae) and an important predator, Carcinops pumilio (Coleoptera: Histeridae), to Beauveria bassiana (Hypocreales: Cordycipitaceae).

House flies (Musca domestica L.) (Diptera: Muscidae) are challenging pests to control. Biological control using Carcinops pumilio beetles may help to reduce house fly populations. However, it is unknown if C. pumilio beetles are compatible with Beauveria bassiana, another house fly biological control option. Five strains of commercially available (GHA, HF23, and L90) and newly discovered (NFH10 and PSU1) strains of B. bassiana were used to test the comparative susceptibility of adult house flies and adult C. pumilio using different laboratory exposure methods. Adult house flies were susceptible to B. bassiana in contact filter paper assays (89%-98% mortality) and immersion assays (100% mortality) at the same 108 conidia suspension using 0.1% CapSil as an aqueous surfactant. Carcinops pumilio were less susceptible than flies to B. bassiana infection using the contact and immersion assays at the same 108 conidial concentration, with 4.4%-12.2% and 8.3%-24.6% mortality, respectively. Immersion in an aqueous conidial suspension resulted in higher mortality compared to contact with treated filter papers at the same 108 concentration with house flies and beetles. We conclude that C. pumilio can safely be used as a biological control agent for house flies with B. bassiana in animal production systems.

Carbonation and corrosion of steel in fly ash concrete, concluding investigation of five-year-old laboratory specimens and preliminary field data

Carbonation development and reinforcement corrosion were investigated on concretes exposed for a five-year period at 90% RH, 20 ℃, and 5% CO2, and for a six-year period at natural carbonation. Portland cement-based binders with 0%, 18%, and 30% fly ash were investigated. The fly ash blends showed lower carbonation resistance compared to PC both at laboratory and field exposure, a large difference in carbonation performance was observed between the laboratory exposed specimens. The carbonation rate was fastest on the laboratory specimens and showed square-root time dependency the first 2.5 years, but reduced rate at later age. Deeper carbonation depths were in general observed in the vicinity of the reinforcement compared to the unreinforced laboratory exposed specimens. Not all specimens were fully carbonated at the steel-concrete interface. The correlation between degree of carbonation of the steel-mortar interface, the open circuit potential, and the observed corrosion of the steel bars varied between binders and bar position (top or bottom). The measured corrosion rate in the laboratory exposed (90% RH, 20 ℃, and 5% CO2) carbonated concrete was on average 0.2 μA/cm2, with an upper value of 0.6 μA/cm2. The highest corrosion rate was measured in the fly ash concrete. No corrosion rate data are yet available for the field exposed concretes.

Canadian laboratory incidents with human pathogens and toxins: An overview of reports, 2016-2022.

When the Public Health Agency of Canada's Human Pathogens and Toxins Act and Human Pathogens and Toxins Regulations came into force, the reporting of laboratory incidents to the Laboratory Incident Notification Canada (LINC) surveillance system became mandatory. This report summarizes the laboratory exposure and non-exposure data reported from 2016 to 2022, with a particular focus on factors that are not typically presented in LINC's annual report. Reported laboratory incidents from 2016 to 2022 were analyzed. Exposures were analyzed by severity, occurrence and root cause, and affected individuals were analyzed by disease outcome, role and applied interventions. Non-exposures were analyzed by incident type. Exposure and non-exposure incident rates were calculated. Events reported to LINC totalled 928. Of those, 355 were confirmed non-exposures, 361 were confirmed exposures, and 111 were other events. Both exposure and non-exposure incident rates per 100 active licences peaked in 2018 (9.44 and 7.11, respectively). Most exposures were rated as minor or negligible severity. The most cited exposure occurrence types were sharps-related and procedure-related (23% each), and standard operating procedure-related root causes were most cited (24%). While 781 individuals were affected in the exposure incidents, most did not develop a laboratory-acquired infection (n=753; 96%) and received at least one form of treatment post-exposure (n=717; 92%). Inadvertent possession/production cases were the most common non-exposure incidents reported. Exposure and non-exposure incident rates have decreased since 2018. Among exposure incidents, sharps-related and procedure-related occurrences were the most common, and the root cause was usually a standard operating procedure. Non-exposure incidents were mostly inadvertent possession/production cases. Exposure and illness outcome severity was mostly minor.

Evidence that personalized racial stress procedures elicit a stress response and increases alcohol craving among Black adults with alcohol use disorder: A laboratory pilot study

BackgroundThe objective of this study was to pilot test newly developed personalized imagery procedures to investigate the impact of racial stress on alcohol craving and emotional and physiological response in Black adults with alcohol use disorder (AUD). MethodsTwenty Black adults (45% women, meanage=37.05, SDage=13.19) with AUD participated in two sessions. In the first, participants described a stressful personal event involving their race and a neutral relaxing situation and these descriptions were used to develop scripts for the subsequent laboratory exposure session. The second session was an experimental provocation session in which participants reported on alcohol craving and emotional response before and after imagined exposure to stress and neutral conditions using personalized racial stress and neutral/relaxing scripts. Conditions were randomized and counterbalanced across subjects, and heart rate and blood pressure were assessed before and after each image. ResultsAlcohol craving and negative emotions significantly increased, and positive emotions decreased following the racial stress script relative to the neutral/relaxing script. We found no differences in physiological response. Exploratory analyses found that increase in alcohol craving was correlated with racial identity exploration but not racial identity commitment, men reported greater reductions in anger than women in the neutral condition only, and income was correlated with fear in the racial stress condition only. ConclusionsThis study provides evidence that personalized racial stress procedures elicit a stress response and increases alcohol craving and emotional response but not physiological response among Black adults with AUD. These findings warrant replication in a larger study.

Per- and polyfluoroalkyl substances induce lipid metabolic impairment in fish: Integration on field investigation and laboratory study

The biotoxicity of perfluoroalkyl and polyfluoroalkyl substances (PFASs) to aquatic organisms has been widely concerned. However, studies on toxic effects of PFASs are usually evaluated directly by using laboratory exposure rather than laboratory validation based on data obtained in the field. In this study, wild catfish (Silurus meridinalis) was explored on the relationship between PFASs bioaccumulation and lipid disorders. Nine and thirteen lipid metabolites were significantly associated with perfluorooctane sulfonate (PFOS) and 6:2/8:2Cl-PFESA (trade name F-53B) exposures, respectively; and the correlated lipid metabolites were the fatty acid (FA) and conjugates, FA esters, steroids, and glycerophosphate subclasses. The effects of PFASs on lipid metabolism of fish and its mechanism were further analyzed through exposure experiments. Zebrafish (Danio rerio) of different sexes underwent PFOS and F-53B exposures for 21 days at 100 ng/L and 100 μg/L. By determining gene expression levels, hepatic lipid contents, and histopathological change, the adverse effects order on lipid metabolism in male or female was 100 μg/L F-53B > 100 μg/L PFOS > 100 ng/L F-53B > 100 ng/L PFOS; the stress response in male was more intensive than that in female. PFOS and F-53B activated the peroxisome proliferator-activated receptor pathway, promoting the processes of FA and total cholesterol (T-CHO) transport, FA β-oxidation, FA synthesis, and finally induced FA and T-CHO transportation from blood into liver, then accelerated FA to FA ester transformation, and CHO into steroids. Laboratory experiments confirmed the field analysis. This study innovatively explored the adverse effects of PFOS and F-53B on lipid metabolism and their mechanisms at field and laboratory levels, highlighting concerns regarding PFASs health risks.

Genetic variation in the CYP1A gene caused by laboratory exposure of benzo (a) pyrene to common carp

Polycyclic aromatic hydrocarbons (PAHs) are pervasive environmental contaminants, with benzo(a)pyrene (B(a)P) standing out as a prototypical example. B(a)P is a known mutagen and carcinogen that, upon metabolic activation stimulated by cytochromes P450 (CYP1A) with microsomal epoxide hydrolase, reacts with DNA. In this study, common carp (Cyprinus carpio) were subjected to three different doses of B(a)P (1μg/kg and 10μg/kg) to investigate the mutagenic effects on B(a)P-derived DNA in vivo.Blood samples were collected, followed by thorough DNA extraction and polymerase chain reaction analysis. The findings revealed a pronounced mutational impact of B(a)P on the amplified segment of the CYP1A gene. Specifically, at a concentration of 1μg/kg, B(a)P induced 8 mutations, 3 amino acid alterations, and the emergence of 5 new haplotype patterns. In contrast, at a concentration of 10μg/kg, B(a)P resulted in 21 mutations, 10 changes in amino acids, and the generation of 7 new haplotype patterns. Additionally, alterations in the three-dimensional protein composition were observed in both dosage groups.This study underscores the significant mutagenic potential of B(a)P, shedding light on its capacity to induce genetic changes and protein structure modifications, thereby emphasizing the importance of monitoring and addressing the environmental presence of PAHs for both ecological and human health considerations

A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures.

Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physiological processes that control Cu and Cd uptake and loss using a biokinetic bioaccumulation model. Larvae of each taxon were experimentally exposed to either water or food enriched with stable isotopes (65Cu and 106Cd). Dissolved Cu uptake (ku) was similar between species (2.6-3.4 L-1g 1d-1), but Cd uptake was 3-fold higher in Hydropsyche than Arctopsyche (1.85 L-1g 1d-1 and 0.60 L-1g 1d-1, respectively). Cu and Cd efflux rates (ke) were relatively fast (0.14 d-1-0.24 d-1) in both species, and may explain, in part, their metal tolerance to mine-impacted rivers. Food ingestion rates (IR), assimilation efficiency (AE) of 65Cu and 106Cd from laboratory diets were also derived and used in a biodynamic model to quantify the relative contribution of dissolved and dietary exposure routes. Results from the biodynamic model were compared to tissue concentrations observed in a long-term field study and indicated that because dissolved Cu and Cd exposures accounted for less than 20% of body concentrations of either taxon, dietary exposure was the predominant metal pathway. An estimation of exposure history was determined using the model to predict steady state concentrations. Under constant exposure conditions (dissolved plus diet), steady state concentrations were reached in less than 30 days, an outcome largely influenced by rapid efflux (ke).

Unhealthy air quality secondary to wildfires is associated with lower blastocyst yield

To study the impact of unhealthy air quality from the 2020 Oregon wildfires on outcomes for patients undergoing invitro fertilization (IVF) treatment. A retrospective cohort study. A university-based fertility clinic. Subjects were undergoing IVF treatment from the 6 weeks preceding the wildfires through a 10-day exposure period. Cohorts were classified on the basis of whether subjects experienced patient and/or laboratory exposure to unhealthy air quality. Patient exposure was defined as at least 4 days of ovarian stimulation overlapping with the exposure, and laboratory exposure was defined as at least 2 days of IVF treatment and embryogenesis overlapping with the exposure. The unexposed cohort consisted of remaining subjects without defined exposure, with cycles in the 6 weeks preceding the wildfires. As some subjects had dual exposure and appeared in both patient and laboratory exposure cohorts, each cohort was separately compared with the unexposed control cohort. A 10-day period of unhealthy air quality caused by smoke plumes from a wildfire event. The primary outcome was the blastulation rate. Secondary outcomes included fertilization rate, number of blastocysts obtained, and cycles with no blastocysts frozen or transferred. Sixty-nine subjects underwent ovarian stimulation and IVF treatment during the 6 weeks preceding the wildfires through the 10-day period of unhealthy air quality. Of these, 15 patients were in the laboratory exposure cohort, 16 were in the patient exposure cohort, and 44 were unexposed. Six subjects appeared in both laboratory and patient exposure cohorts. Although neither exposure cohort had significantly decreased blastulation rate compared with the unexposed, the median number of blastocysts obtained was significantly lower in the laboratory exposure cohort than the unexposed group (2 [range 0-14] vs. 4.5 [range 0-21], respectively). The laboratory exposure cohort had significantly more cycles with no blastocysts obtained (3/15 [20%] vs. 1/44 [2%]). There were no significant differences in IVF treatment outcomes between patient exposure and unexposed cohorts. These findings persisted after controlling for age. There were no significant differences in pregnancy outcomes observed after embryo transfer between the exposure group and the unexposed group. For a cohort of patients undergoing IVF treatment, an acute episode of outside wildfire smoke exposure during fertilization and embryogenesis was associated with decreased blastocyst yield.

Thermal Threats to Freshwater Mussels: An Empirical Stream Assessment

Freshwater mussels fulfill an important ecological role in aquatic ecosystems, but they currently face many threats, including thermal regime alteration. Thermal transformation of the aquatic environment is associated with climate change, land use alteration, and other pervasive anthropogenic global changes. To enhance our understanding of ecological thermal impacts, we combined extensive field measurements of temperature in the stream water column and substrate depths (5 and 15 cm) at sites where mussels occur, measures of abundance and species richness for mussels and fish, and thermal tolerance knowledge for mussels and fish to generate a comprehensive assessment of the potential threats mussels face as temperatures continue to rise as a result of global change. Mean summer (June–August 2010–2012) temperatures at mussel-occupied sites in the upper Tar River basin of North Carolina, USA, ranged from 16.2 to 34.7 °C. The mean temperature from the hottest 96 h at each site ranged from 23.5 to 31.5 °C. At 80% of sites, a period of moderate drought coincided with the hottest 96 h period. Temperature threshold exceedance durations indicated that chronic, combined chronic/acute, and acute freshwater mussel thermal tolerance thresholds (i.e., 28 °C, 30 °C, and 33 °C, respectively) based on laboratory exposures of glochidia (larvae) and juveniles were commonly exceeded. Water temperatures exceeded 28 °C for at least 24 h at 55% of sites and for at least 96 h at 35% of sites, and they exceeded 30 °C for at least 24 h at 15% of sites. We quantified a thermal buffering effect of the substrate that may be protective of mussels. There was a mean difference of 0.5 °C between the water column and the upper substrate (5 cm) and a mean difference of 0.9 °C between the water column and the lower substrate (15 cm). Maximum differences of up to 5.5 °C between the water column and the upper substrate and 11.5 °C between the water column and the lower substrate were observed. Our models estimating the relation between the water column and substrate temperatures more realistically characterize ambient temperature exposures and have widespread implications for mussel conservation and climate change risk assessment in similar streams. Freshwater mussels currently exist on the edge of their thermal limits, but their abundance and species richness cannot be explained by temperature patterns alone. Fish species richness was related to the thermal regime, indicating that species interactions may be an important driver of freshwater mussel responses to global change.

Is Anopheles gambiae (sensu stricto), the principal malaria vector in Africa prone to resistance development against new insecticides? Outcomes from laboratory exposure of An. gambiae (s.s.) to sub-lethal concentrations of chlorfenapyr and clothianidin

Indiscriminate use of pesticides in the public health and agriculture sectors has contributed to the development of resistance in malaria vectors following exposure to sub-lethal concentrations. To preserve the efficacy of vector control tools and prevent resistance from spreading, early resistance detection is urgently needed to inform management strategies. The introduction of new insecticides for controlling malaria vectors such as clothianidin and chlorfenapyr requires research to identify early markers of resistance which could be used in routine surveillance. This study investigated phenotypic resistance of Anopheles gambiae (sensu stricto) Muleba-Kis strain using both WHO bottle and tube assays following chlorfenapyr, clothianidin, and alpha-cypermethrin selection against larvae and adults under laboratory conditions. High mortality rates were recorded for both chlorfenapyr-selected mosquitoes that were consistently maintained for 10 generations (24-h mortality of 92–100% and 72-h mortality of 98–100% for selected larvae; and 24-h mortality of 95–100% and 72-h mortality of 98–100% for selected adults). Selection with clothianidin at larval and adult stages showed a wide range of mortality (18–91%) compared to unselected progeny where mortality was approximately 99%. On the contrary, mosquitoes selected with alpha-cypermethrin from the adult selection maintained low mortality (28% at Generation 2 and 23% at Generation 4) against discrimination concentration compared to unselected progeny where average mortality was 51%. The observed resistance in the clothianidin-selected mosquitoes needs further investigation to determine the underlying resistance mechanism against this insecticide class. Additionally, further investigation is recommended to develop molecular markers for observed clothianidin phenotypic resistance.