Biology

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Arousal from hibernation increases blood oxygen saturation in 13-lined ground squirrels
(The Company of Biologists, 2025-04-28) Duffy, Brynne M.; Ivy, Catherine M.; Staples, James F.
Hibernating Ictidomys tridecemlineatus, 13-lined ground squirrels, are considered models of ischaemia–reperfusion tolerance, as both tissues and isolated mitochondria withstand anoxia followed by rapid re-oxygenation in vitro. This tolerance is likely adaptive, protecting against damage during the numerous arousals from torpor throughout the hibernation season. O2 availability is likely low during torpor, but suppressed metabolism lowers O2 demand, potentially mitigating hypoxic stress. During arousal to interbout euthermia (IBE), heart rate, blood pressure and ventilation increase rapidly, suggesting increased O2 availability, but tissue oxygenation has not been measured during arousal or IBE in 13-lined ground squirrels. Using pulse-oximetry collars, we characterized dramatic increases in O2 availability during arousal; carotid artery O2 saturation rose from as low as 35% early in arousal to 87% during IBE. These changes closely followed rising heart rate. Our results demonstrate that hibernating 13-lined ground squirrels survive profound O2 deprivation early in arousal and rapid O2 influx as arousal progresses.
Aqueous Geochemical Controls on the Sestonic Microbial Community in Lakes Michigan and Superior
(MDPI, 2023-02-17) Rani, Asha; Ranjan, Ravi; Bonina, Solidea M.C. ; Izadmehr, Mahsa; Giesy, John; Li, An; Sturchio, Neil; Karl J. Rockne; Rockne, Karl
Despite being the largest freshwater lake system in the world, relatively little is known about the sestonic microbial community structure in the Laurentian Great Lakes. The goal of this research was to better understand this ecosystem using high-throughput sequencing of microbial communities as a function of water depth at six locations in the westernmost Great Lakes of Superior and Michigan. The water column was characterized by gradients in temperature, dissolved oxygen (DO), pH, and other physicochemical parameters with depth. Mean nitrate concentrations were 32 μmol/L, with only slight variation within and between the lakes, and with depth. Mean available phosphorus was 0.07 μmol/L, resulting in relatively large N:P ratios (97:1) indicative of P limitation. Abundances of the phyla Actinobacteria, Bacteroidetes, Cyanobacteria, Thaumarchaeota, and Verrucomicrobia differed significantly among the Lakes. Candidatus Nitrosopumilus was present in greater abundance in Lake Superior compared to Lake Michigan, suggesting the importance of ammonia-oxidating archaea in water column N cycling in Lake Superior. The Shannon diversity index was negatively correlated with pH, temperature, and salinity, and positively correlated with DO, latitude, and N2 saturation. Results of this study suggest that DO, pH, temperature, and salinity were major drivers shaping the community composition in the Great Lakes.
Volatile Constituents in Essential Oil from Leaves of Withania adpressa Coss. Ex Exhibit Potent Antioxidant and Antimicrobial Properties against Clinically-Relevant Pathogens
(MDPI, 2023-03-21) bourhia, mohammed; Alyousef, Abdullah; DOUMANE, Ghizlane; SAGHROUCHNI, Hamza; Giesy, John; lahcen, ouahmane; Fatiha, EL-RHEZOUANI; Al-Sheikh, Yazeed; Aboul-Soud, Mourad
Withania adpressa Coss. ex is a plant used in traditional medications. Antioxidant, antibacterial, and antifungal properties of the essential oil from leaves of Withania adpressa Coss ex. (EOW) were investigated. EOW was extracted using a Clevenger apparatus, and its volatile compounds were characterized by GC-MS. Antioxidant potency was determined using DPPH, FRAP, and TAC assays. Antibacterial effects were determined vs. Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus pneumonia; while its antifungal efficacy was determined vs. Candida albicans, Aspergillus flavus, Aspergillus niger, and Fusarium oxysporum using the disc diffusion and minimum inhibitory concentration bioassays. A chromatographic analysis showed that EOW contained eight phytochemical compounds constituting 99.14% of the total mass of oil. Caryophyllene (24.74%), Longifolene (21.37%), δ-Cadinene (19.08%), and Carene (14.86%) were predominant compounds in EOW. The concentrations required to inhibit 50% of free radical (IC50) values of antioxidant activities of EOW were 0.031 ± 0.006 mg/mL (DPPH), 0.011 ± 0.003 mg/mL (FRAP), and 846.25 ± 1.07 mg AAE/g (TAC). Inhibition zone diameters of EOW vs. bacteria were 18.11 ± 0.5 mm (E. coli), 17.10 ± 0.42 mm (S. aureus), 12.13 ± 0.31 mm (K. pneumoniae), and 11.09 ± 0.47 mm (S. pneumoniae), while MIC values were 51 ± 3, 47 ± 5, 46 ± 3 and 31 ± 1 µg/mL, respectively. Inhibition zone diameters of EOW vs. fungi were 31.32 ± 1.32, 29.00 ± 1.5, 27.63 ± 2.10, and 24.51 ± s1.07 mm for A. flavus, C. albicans, F. oxysporum, and A. niger, respectively. MIC values were 8.41 ± 0.40, 28.04 ± 0.26, 9.05 ± 0.76, and 22.26 ± 0.55 µg/mL, respectively. Importantly, the highest dose of EOW (1 mg/mL) showed negligible (~5%) cytotoxicity against MCF-12, a normal human epithelial cell line derived from the mammary gland, thus underscoring its wide safety and selectivity against tested microbes. To sum it up, EOW has exhibited promising antioxidant and antimicrobial properties, which suggests potential to abrogate antibiotic resistance.
Apoptosis-mediated anti-proliferative activity of Calligonum comosum against human breast cancer cells, and molecular docking of its major polyphenolics to Caspase-3
(Frontiers Media, 2022-10-09) Kumar, Ashok; Alfhili, Mohammad; Bari, Ahmed; Ennaji, Hanane; Ahamed, Professor Maqusood; Bourhia, Mohammed; CHEBAIBI, Mohamed; BENBACER, Laila; Ghneim, Hazem; Abudawood, Manal; Alghamdi, Khalid; Giesy, John; Al-Sheikh, Yazeed; Aboul-Soud, Mourad
Due to poor diagnosis breast cancer in women has emerged as the most common cause of death disease in developing countries. Medicinal plants have been used for thousands of years and can be useful in healthcare, especially in developing countries. Ethanol extracts of leaves of fire bush or arta (Calligonum comosum; EECC), exhibited significant anticancer potencies against two breast cancer cell lines, MCF-7 and MDA 231. These in vitro effects of EECC indicated potential anticancer activities that were determined to be specific since minimal toxicity was recorded against MCF-12, a non-cancerous breast cell line used as a reference. EECC also induced cell cycle arrest in MCF-7 and MDA 231 as revealed by the increased proportions of sub-G1 cells. Fluorescence-activated cell sorter analysis (FACS), utilizing double staining by annexin V-FITC/propidium iodide, revealed that the observed cytotoxic effects were mediated via apoptosis and necrosis. FACS measurement of thegreater in fluorescence intensity, linked with oxidation of DCFH to DCF, revealed that apoptosis was attributable to production of free radicals. EECC-mediated apoptosis was further validated by observation of up-regulation in the “executioner” enzyme, caspase 3. The current findings reveal that EECC exhibits significant, selective cytotoxicity to breast cancer cells, that proceeds via the generation of ROS, which culminates in apoptosis. The anti-proliferative effects of EECC weres further verified by use of a structure-based, virtual screening between its major bioactive polyphenolic constituents and the apoptosis executioner marker enzyme, caspase-3. Based on their glide score values against the active site of caspase 3, some phyto-constituents present in EECC, such as DL-alpha-tocopherol and campesterol, exhibited distinctive, drug-like potential with no predicted toxicity to non-target cells. Taken together, the usefulness of natural phenolic and flavonoid compounds contained in Calligonum comosum were suggested to be potent anticancer agents.
Genetic diversity and phylogeographic relationships of Dermacentor variabilis (Acari: Ixodidae) within an established population in southern Manitoba (Canada), and the prevalence of Rickettsia montanensis and Francisella-like endosymbionts
(Oxford University Press, 2025-04-17) Chilton, Neil B; Thampy, Prasobh R; Wolbaum, Cole R; Sterling, Emily E; Thoroughgood, Jessica T; Berg, Elisabeth D; Halpin, Alexander S; Diyes, Chulantha P; Yunik, Matthew E M; Díaz-Sánchez, Adrian A; Rochon, Kateryn; Lysyk, Timothy J; Dergousoff, Shaun J
The primary objective of this study was to determine if DNA sequences of the mitochondrial (mt) cytochrome oxidase c subunit 1 gene (cox1) and/or the mt 16S ribosomal RNA (rRNA) gene can be used to study the population genetics and phylogeography of the American dog tick, Dermacentor variabilis (Say). DNA sequences were determined for 200 adult ticks collected from an established population in a region of Manitoba (Canada) where there have been recent outbreaks of bovine anaplasmosis. Given this, a secondary objective was to test these ticks for the presence of Anaplasma marginale Theiler and 2 other bacterial pathogens, Rickettsia rickettsii Brumpt and Francisella tularensis (McCoy and Chapin 1912) Dorofe’ev 1947. However, no ticks were PCR-positive for these bacteria, whereas 15% of ticks were PCR-positive for R. montanensis Weiss and Moulder and 96% contained Francisella-like endosymbionts. Nucleotide and haplotype diversity among ticks was greater for cox1 than the 16S rRNA gene, thus cox1 is more useful for examining the genetic diversity within and among D. variabilis populations. The 33 cox1 haplotypes could be separated into 3 haplogroups, but when combined with sequence data from GenBank, 6 clades were evident, 2 of which comprised ticks from primarily Saskatchewan, Manitoba, western Ontario, South Dakota, and Wisconsin. These findings indicate that cox1 can be used to understand the phylogeography of D. variabilis, but more sequences are needed from individuals in other populations across geographical range of this tick species, particularly those on the Canadian prairies where D. variabilis is undergoing range expansion.
Lipid remodeling during early development of rainbow trout (Oncorhynchus mykiss)
(Elsevier, 2024-02-29) Wang, Chao; Gong, Yufeng; Deng, Fuchang; Liu, Xin; Ding, Enming; Zhang, Shuyi; Ma, Xiao; Raine, Jason; Jones, Paul; Tang, Song; Giesy, John
Lipids play a crucial role in a range of physiological processes, with a particular significance during the early development stages. However, our understanding of lipid remodeling in cold-water salmon species during these critical early developmental phases remains limited. To address this, a comprehensive lipidomic study was conducted using rainbow trout (Oncorhynchus mykiss) as a model and four critical developmental stages were selected for analysis (i.e., newly fertilized eggs, eyed stage, post-hatch sac-fry stage, and swim-up stage). As expected, our results demonstrated significant lipid alterations during early development of rainbow trout. Through fuzzy c-mean clustering analysis, our study further provided a detailed description on the dynamic changes and regulation of the lipidome. Most unsaturated phosphatidylcholines (PCs) excluding very long-chain polyunsaturated PCs and all polyunsaturated triacylglycerols (TGs) were continuously consumed, suggesting that they are the major energy sources and/or precursor substances for early-stage development in rainbow trout. Gradual increases in very long-chain polyunsaturated phosphatidylethanolamines (PEs) and PCs, phosphatidylserines (PSs), as well as saturated and monounsaturated sphingomyelins (SMs) were observed in this study, which may closely associate with retina and brain development, and the myelination process. Additionally, diacylglycerol (DG), a well-known second messenger, displayed continuous synthesis throughout embryogenesis in this study. In addition to the abovementioned lipid dynamics, our study also found distinct patterns of change in certain glycerophospholipids (GP) isomers, while all glycerolipid (GL) isomers exhibited consistent trends in alteration, indicating different GP isomers may have different biological functions or activities for early development. Overall, this study emphasized the significant roles of lipids during the early development of rainbow trout and served as an informational data set for fish development-related research.
A method to determine reactive oxygen species production in intestinal and liver cell cultures using the 2 ′ ,7 ′ -dichlorodihydrofluorescein diacetate assay
(Elsevier, 2024-02-13) Engelbrecht, Ilzé; Horn, Suranie; Giesy, John; Pieters, Rialet
Exposure to xenobiotics can increase the production of reactive oxygen species (ROS). When detoxification organs such as the intestines and liver cannot neutralise these xenobiotics, it can induce oxidative stress and cause damage to tissues. Therefore, cell-based bioassays that indicate intracellular ROS production are a useful screening tool to evaluate the effect of these chemicals. Although flow cytometry is commonly used to measure ROS in cells, many research laboratories in the Global South do not always have access to such specialised instrumentation. Therefore, we describe a sensitive but low-cost method that can easily be used to determine ROS production in vitro. This method employs the fluorogenic dye, 2′,7′-dichlorodihydrofluorescein diacetate (H2DCF-DA), which emits fluorescence after being oxidised to a fluorescent derivative. Since the H2DCF-DA bioassay indicates non-specific ROS production it can be used as a marker of overall oxidative stress. This method was validated by exposing human duodenum epithelial adenocarcinoma (HuTu-80) and rat liver epithelial hepatoma (H4IIE-luc) cells to agricultural soil samples.
Chemical composition, sources, and ecological effect of organic phosphorus in water ecosystems: a review
(Springer Nature, 2023-03-15) Feng, Weiying; Wang, Tengke; Zhu, Yuanrong; Sun, Fuhong; Giesy, John; Wu, Fengchang
Phosphorus (P) affects the water–air CO2 flux through primary productivity, and affects the changes of carbon cycle and ecological environment in the global world. Organic phosphorus (Po) is an important P component in water environments. Various processes control the formation and transformation of Po and outbreaks of algal blooms. Here, research topics on Po in global water over the past 50 years are systematically reviewed to understand the progress in the (i) Po pretreatment techniques in various media, (ii) technical methods and qualitative and quantitative research on chemical composition of Po and bioavailability, (iii) source analysis of and factors affecting Po in different media of water environments and biogeochemical processes, (iv) interactions among Po, organic matter, and minerals, and their environmental behaviors, and (v) quantification of material exchanges at the sediment–water interface, interfacial processes, and ecological effects. Finally, the future research directives regarding Po in water environments are discussed. The findings provided an important scientific basis to formulate and revise global standards for water nutrients and a better understanding of water eutrophication and its control.
Exploring the essence of celery seeds (Apium graveolens L.): Innovations in microwave-assisted hydrodistillation for essential oil extraction using in vitro, in vivo and in silico studies
(Scientific Scholar, 2024-03-11) NOUIOURA , Ghizlane ; El fadili, Mohamed; Ghneim, Hazem; Zbadi, Latifa; Maache, Souad; Otmane, Zouirech; Danouche, DANOUCHE; Aboul-Soud, Mourad; Giesy, John; badiaa, lyoussi; derwich, elhoussine
This study presents the composition analysis of essential oils extracted from celery seeds (Apium graveolens L.) collected from Morocco. Essential oil of A. graveolens (AG-EO), were obtained through microwave-assisted hydro- distillation, and its composition was characterized using gas chromatography/mass spectrometry (GC/MS). antimicrobial properties were assessed utilizing disc diffusion and microdilution assay methods, while antioxidant activities were evaluated through spectrophotometric techniques. Additionally, in vivo anti-inflammatory effects were investigated. The molecular docking technique, a computational approach utilized to predict the binding of small molecules to specific proteins, was employed to elucidate the antioxidative and antibacterial characteristics of the constituent molecules. The physicochemical and pharmacokinetic features of absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox) tests were anticipated to provide insights into the drug likeness, pharmacokinetic characteristics, and expected safety profiles upon ingestion and the potential pharmacological activity of the identified compounds. Fifteen constituent compounds representing 99.99% of AG-EO were identified and quantified by the use of GC/MS. The main constituent, comprising 64.58% of AG-EO was limonene. AG-EO demonstrated a significant DPPH free radical scavenging activity, showing estimated scavenging rates of 8.49±0.00 µg/mL, and 5.09±0.04 µg/mL for ABTS+. AG-EO exhibited reducing Power (RP) and total antioxidant activity (TAC) of 3.42±0.01 µg/mL and 245.93±0.04 mg AAE/mL, respectively. AG-EO exhibited significant antimicrobial activity against all tested microorganisms. Additionally, the anti- inflammatory activity demonstrated the remarkable efficacy of AG-EO. Taken together, the essential oil derived from celery seeds holds promise for large-scale utilization as an environmentally friendly preservative within the food and agriculture industries, effectively countering fungal growth and aflatoxin contamination in stored commodities. Additionally, it exhibits potential as a suitable candidate for the development of pharmaceutical drugs.
Comprehensive analysis of diferent solvent extracts of Ferula communis L. fruit reveals phenolic compounds and their biological properties via in vitro and in silico assays
(Nature, 2024-05-31) NOUIOURA , Ghizlane ; El fadili, Mohamed; El barnossi, Azeddin; LOUKILI, EL Hassania; LAAROUSSI, Hassan; BOUHRIM, Mohamed; Giesy, John; Aboul-Soud, Mourad; Al-Sheikh, Yazeed; badiaa, lyoussi; Derwich, El Houssine
Although giant fennel is recognized as a “superfood” rich in phytochemicals with antioxidant activity, research into the antibacterial properties of its fruits has been relatively limited, compared to studies involving the root and aerial parts of the plant. In this study, seven solvents—acetone, methanol, ethanol, ethyl acetate, chloroform, water, and hexane—were used to extract the chemical constituents of the fruit of giant fennel (Ferula communis), a species of flowering plant in the carrot family Apiaceae. Specific attributes of these extracts were investigated using in silico simulations and in vitro bioassays. High-performance liquid chromatography equipped with a diode-array detector (HPLC–DAD) identified 15 compounds in giant fennel extract, with p-coumaric acid, 3-hydroxybenzoic acid, sinapic acid, and syringic acid being dominant. Among the solvents tested, ethanol demonstrated superior antioxidant activity and phenolic and flavonoid contents. F. communis extracts showed advanced inhibition of gram-negative pathogens (Escherichia coli and Proteus mirabilis) and variable antifungal activity against tested strains. Molecular docking simulations assessed the antioxidative, antibacterial, and antifungal properties of F. communis, facilitating innovative therapeutic development through predicted compound–protein interactions. In conclusion, the results validate the ethnomedicinal use and potential of F. communis. This highlights its significance in natural product research and ethnopharmacology.
HPLC, NMR Based Characterization, Antioxidant and Anticancer Activities of Chemical Constituents from Therapeutically Active Fungal Endophytes
(The Korean Society for Microbiology and Biotechnology, 2024-01-01) Shah, Waqas Hussain; Khan, Wajiha; nisa, sobia; Barfuss, Michael; Schinnerl, Johann; Bacher, Markus; Vetschera, Karin; Ali, Ashraf; Nafidi, Hiba-Allah; BIN JARDAN, YOUSEF; Giesy, John
Fungi generate different metabolites some of which are intrinsically bioactive and could therefore serve as templates for drug development. In the current study, six endophytic fungi namely Aspergillus flavus, Aspergillus tubigenesis, Aspergillus oryzae, Penicillium oxalicum, Aspergillus niger, and Aspergillus brasiliensis were isolated and identified from the medicinal plant, Silybum marianum. These endophytic fungi were identified through intra transcribed sequence (ITS) gene sequencing. The bioactive potentials of fungal extracts were investigated using several bioassays such as antibacterial activity by well-diffusion, MIC, MBC, anti-biofilm, antioxidant, and haemolysis. The Pseudomonas aeruginosa PAO1 was used to determine the antibiofilm activity. The ethyl acetate extract of Aspergillus flavus showed strong to moderate efficacy against Staphylococcus aureus, Escherichia coli, P. aeruginosa, and Bacillus spizizenii. Aspergillus flavus and Aspergillus brasiliensis exhibited significant antibiofilm activity with IC50 at 4.02 and 3.63 mg/ml, while A. flavus exhibited maximum antioxidant activity of 50.8%. Based on HPLC, LC-MS, and NMR experiments kojic acid (1) and carbamic acid (methylene-4, 1-phenylene) bis-dimethyl ester (2) were identified from A. flavus. Kojic acid exhibited DPPH free radical scavenging activity with an IC50 value of 99.3 μg/ml and moderate activity against ovarian teratocarcinoma (CH1), colon carcinoma (SW480), and non-small cell lung cancer (A549) cell lines. These findings suggest that endophytic fungi are able to produce promising bioactive compounds which deserve further investigation.2
Mixtures of legacy and replacement perfluorosulphonic acids (PFSAs) demonstrate ratio-, concentration- and endpoint-dependent synergistic interactions in vitro
(Elsevier, 2024-05-25) Mahoney, Hannah; da Silva, Francisco; Brinkmann, Markus; Giesy, John
The extensive use of poly- and per-fluoroalkyl substances (PFASs) has les to their widespread presence in the environment, raising concerns about potential toxicity. While certain PFASs of concern have been phased-out or banned, new PFASs continue to be produced. Two such substances are perfluoroethylcyclohexane sulphonate (PFECHS) and perfluorobutane sulphamide (FBSA), replacements of perfluoroctanesulphonic acid (PFOS) that have recently been detected in multiple environmental media around the globe. Despite PFASs generally occurring in the environment as mixtures, few data are available outlining the effects of PFAS mixtures. Therefore, this research investigated the interaction potential of binary and ternary mixtures of emerging and legacy PFASs. The immortalized rainbow trout gill cell line (RTgill-W1) was chosen as the experimental model to investigate two apical endpoints: cytotoxicity and phospholipidosis. RTgill-W1 cells were exposed for 24 h to each compound to obtain endpoint-specific effect concentrations (LCx; ECx). These values were then applied to formulate mixture predictions following the Loewes Additivity and Steel and Peckham methods. Based on cytotoxicity, relative potencies of individual compounds were: PFOS > PFECHS > FSBA. PFOS and PFECHS had nearly identical effects on phospholipidosis, while FSBA did not have any effects. Most mixtures had a synergistic effect on cytotoxicity, but the effect was both dose- and ratio-dependent. PFOS and PFECHS were additive at lower concentrations (LC10) and synergistic at higher concentrations (LC50; 3:1, 1:1, and 1:3). PFECHS and FSBA mixtures were synergistic at all doses and ratios (3:1, 1:1, 1:3), while FBSA and PFOS were mainly synergistic at higher concentrations and at ratios favouring PFOS (1:1, 1:3). Tertiary combinations were mainly synergistic. For phospholipidosis, mixtures were strictly additive. These results are strongly suggestive of synergism between emerging PFAS replacements and highlight that independent apical mechanisms of different PFASs could combine to induce unexpected toxicity. Considering that emerging replacements are continuing to increase in concentration in the environment, such mixture scenarios are also likely to continue to increase in probability.
A comparison of seasonal flexibility in pectoralis muscle fiber type and enzyme activity in migratory and resident sparrow species
(The Company of Biologists, 2025-02) Lewicki, Louisa M.; Zhang, Marina; Staples, James F.; Guglielmo, Christopher G.; Ivy, Catherine
The pectoralis muscle in birds is important for flight and thermogenesis. In migratory songbirds this muscle exhibits seasonal flexibility in size, but whether this flexibility reflects changes in muscle fiber type has not been well documented. We investigated how seasonal changes in photoperiod affected pectoralis muscle fiber type and metabolic enzymes, comparing among three closely related sparrow species: two seasonal migrants and one year-round, temperate climate resident. We quantified fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers histologically, and measured activities of citrate synthase (CS) and lactate dehydrogenase (LDH) in the pectoralis muscle of the three species that were acclimated to long or short periods of daylight. In all species, FOG was the predominant fiber type, but song sparrows had FG fibers regardless of daylight conditions. By contrast, Lincoln's sparrows incorporated FG fibers only under short-daylight conditions, and house sparrows did not significantly express FG fibers, regardless of daylight length. Both migratory species increased LDH activity in short-daylight conditions but did not alter CS activity. In contrast, resident house sparrows did not alter CS or LDH activity with changes in daylight length. Our findings suggest that the presence of FG fibers is important for seasonal flexibility in LDH activity. Additionally, migratory species exhibited seasonal flexibility in muscle fiber type and enzyme activity, presumably to support migratory flight, while the resident species did not exhibit such seasonal flexibility, suggesting that this consistent phenotype is important year-round, despite changing thermogenic requirements.
Neurodevelopmental and behavioural effects of waterborne selenite in larval zebrafish (Denio rerio)
(Elsevier, 2025-02-26) Uddin, Md Helal; Ritu, Jinnath Rehana; Chivers, Douglas P.; Niyogi, Som
Selenium (Se) is an essential element that becomes highly toxic to fish at elevated exposure levels. Although the neuro-behavioural effects of organic Se are well documented in adult fish, the effects of inorganic Se (selenite) on neurodevelopment and behaviour, particularly in early life stages, remain poorly understood. In this study, zebrafish embryos were exposed to different environmentally relevant concentrations of waterborne Se (0 (control), 10, 50, 100 μg/L; as selenite) from 4 hours post-fertilization to 30 days post-fertilization. We evaluated neurodevelopmental and behavioural outcomes, along with oxidative stress as a potential mechanism of selenite neurotoxicity. Fish larvae exposed to higher Se concentrations (50 and 100 μg/L) exhibited significant behavioural impairments, including reduced thigmotaxis and reflexive movement, spent significantly less time (60 %) near their conspecifics, and lower exploratory response (1.5 fold) to the novel object. These behavioural deficits were associated with elevated oxidative stress, as indicated by increased (5.4 fold) DCF-DA fluorescence intensity and dysregulation (0.6–6.4 fold change) of key antioxidant genes. Additionally, selenite exposure led to increased apoptotic cell death (p < 0.001), and reduced length (16 %) and weight (33–47 %) of zebrafish larvae in 50 and 100 μg/L Se exposure groups compared to the control group. Neurodevelopmental disruptions were evident through altered expression of dopaminergic (mao, th1, otpa; all p < 0.05) and serotonergic (tph2, pet1, 5ht2c; all p < 0.05) pathway genes, critical regulators of behaviour in fishes. Overall, our findings suggest that selenite-induced oxidative stress and neurodevelopmental gene dysregulation contribute to the observed behavioural impairments in developing zebrafish, highlighting the potential risks of Se exposure during early life stages.
The catecholamine response to graded high-altitude ﬂight in yellow-rumpedwarblers (Setophaga coronata)
(American Physiological Society, 2025-03) Ivy, Catherine; Young, Kevin; Qu, Melanie; Dick, Morag F; Shoemaker, Kevin; Guglielmo, Christopher G.
Chronic exposure to low oxygen (hypoxia) leads to amplification of the hypoxic chemoreflex, increasing breathing and sympathetic nervous system (SNS) activation. Prolonged SNS activation redistributes blood to hypoxia-sensitive tissues away from muscles. Recent tracking studies have shown that migratory songbirds can fly 5,000 m or higher above sea level, leading us to hypothesize that migratory birds may have a blunted hypoxic chemoreflex to maintain blood flow to muscles during migratory flight at high altitudes. To test this hypothesis, we used a hypobaric wind tunnel and measured circulating plasma catecholamines after maximal altitude flight, flight at 75% of maximal altitude, flight at ground level (∼250 m), and after rest at 75% of maximal altitude and ground level in migratory myrtle yellow-rumped warblers (Setophaga coronata). Yellow-rumped warblers were capable of flying above 4,000 m simulated altitude above sea level (average maximum altitude of ∼3,600 m) and would maintain flights at 75% of individual maximum altitudes (∼2,700 m). Circulating dopamine and noradrenaline were similar between resting and flight conditions at ground level and with exposure to 75% of maximal altitude, whereas adrenaline significantly increased with flight, but did not change further with flight at 75% of maximal altitude. In contrast, both adrenaline and noradrenaline concentrations increased after maximum altitude flights compared with 75% and ground-level flights. Our findings show that exercise increases plasma adrenaline in migratory songbirds and suggest that warblers flying at high altitudes below their maximum altitude may be minimally hypoxic, allowing them to maintain oxygen transport to flight muscles. NEW & NOTEWORTHY Yellow-rumped warblers, a small songbird that conducts migratory flights, were found to fly to altitudes above 4,000 m above sea level in simulated flights using a hypobaric wind tunnel. Circulating adrenaline suggests that warblers flying at 75% of individual maximum altitudes are not experiencing arterial hypoxia, allowing them to maintain aerobically demanding migratory flight at high altitudes.
A comparison of seasonal flexibility in pectoralis muscle fiber type and enzyme activity in migratory and resident sparrow species
(Journal of Experimental Biology, 2024-02) Lewicki, Louisa M.; Zhang, Marina; Staples, James; Guglielmo, Christopher G.; Ivy, Catherine
The pectoralis muscle in birds is important for flight and thermogenesis. In migratory songbirds this muscle exhibits seasonal flexibility in size, but whether this flexibility reflects changes in muscle fiber type has not been well documented. We investigated how seasonal changes in photoperiod affected pectoralis muscle fiber type and metabolic enzymes, comparing among three closely related sparrow species: two seasonal migrants and one year-round, temperate climate resident. We quantified fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers histologically, and measured activities of citrate synthase (CS) and lactate dehydrogenase (LDH) in the pectoralis muscle of the three species that were acclimated to long or short periods of daylight. In all species, FOG was the predominant fiber type, but song sparrows had FG fibers regardless of daylight conditions. By contrast, Lincoln's sparrows incorporated FG fibers only under short-daylight conditions, and house sparrows did not significantly express FG fibers, regardless of daylight length. Both migratory species increased LDH activity in short-daylight conditions but did not alter CS activity. In contrast, resident house sparrows did not alter CS or LDH activity with changes in daylight length. Our findings suggest that the presence of FG fibers is important for seasonal flexibility in LDH activity. Additionally, migratory species exhibited seasonal flexibility in muscle fiber type and enzyme activity, presumably to support migratory flight, while the resident species did not exhibit such seasonal flexibility, suggesting that this consistent phenotype is important year-round, despite changing thermogenic requirements.
Environment consistently impact on aquaculture: The predominant source of residual pollutants in cultured Chinese mitten crab (Eriocheir sinensis) across China
(Elsevier, 2024-06-04) Fang, Longxiang; Chen, Xi; Fan, Limin; Hu, gengdong; Qiu, Liping; Song, Chao; Xie, Yuwei; Giesy, John; Wang, Changbo; shunlong, meng
Advancements in monitoring and operation of aquaculture environments has minimized the concentrations of some residual pollutants in cultured aquatic products. However, currently most aquatic products are “farmed”, and relationships among residual pollutants in tissues of crabs were still unclear. In this study, 64 typical pollutants, including 25 antibiotics, 15 metal, 23 organochlorine pesticides, and one dioxin-like compound inducing hydrocarbon-receptor (AHR) activity were measured in Chinese mitten crab (Eriocheir Sinensis) risks of consumption assessed and ranked. The superposition of properties including severity and relative potency of effects and parameters describing persistence and exposure along with rates of usage and identification of groups most likely to be exposed were assessed in combination to rank likelihood of dietary exposure and probabilities of adverse effects for each contaminant. The results indicated that the total scores per pollutants found that Cadmium (Cd), Heptachlor epoxide (HEPE), dioxin TEQ exhibited the greatest scores and explained the severity of dietary risk, while source analysis.
Collar? I barely know her: The utility of accelerometry in measuring personality in situ for a free-ranging wild mammal
(Elsevier, 2025-01-10) Sanders, Jonas; Studd, Emily; Dantzer, Ben; Wishart, Andrea; Gaidica, Matt; Ruckstuhl, Kathreen; Boutin, Stan; Lane, Jeffrey; Martinig, April Robin
The study of personality in animals requires methods for quantifying consistent among-individual differences in behaviour. Typically, standardized behavioural assays are used rather than in situ tools. We evaluated whether assays and accelerometry, a relatively novel method of quantifying animal behaviour in the field, yielded similar personality measurements in a wild population of North American red squirrels, Tamiasciurus hudsonicus, by comparing among-individual correlations of behaviours across these methods. Both methods described two behavioural axes, with assays capturing activity and exploration, and accelerometry capturing foraging and movement. We found higher trait repeatability (R) for traits measured with assays (Radj: adults: 0.37–0.40; yearlings: 0.18–0.48) than for traits measured with accelerometry (Radj: adults 0.11–0.19; yearlings: 0.07–0.11). Additionally, we found a significant positive among-individual correlation between the assay behavioural axis associated with exploration and the accelerometry behavioural axis associated with foraging. We also found that the repeatability of traits measured with accelerometry was related to the amount of behavioural data captured by this method. Given that accelerometry was able to quantify animal personality in situ for adults, accelerometer collars may present a possible alternative to assays for species in which assays are impractical. Our results also underscore the importance of considering the amount of behavioural data captured by different methods when assessing trait repeatability. As researchers strive to measure behavioural variation under natural conditions, sufficient behavioural sampling remains a priority.
Migration strategy and constraint in migration behavior vary among shorebird species with different life histories
(Wiley, Ecological Society of America, 2025-01-15) Clements, Sarah J.; Loghry, Jason P.; Linscott, Jennifer; Ruiz, Jorge; Gunn, Joe; Navedo, Juan G.; Senner, Nathan; Ballard, Bart; Weegman, Mitch
Migration strategy is a key behavioral characteristic guiding how migratory species time their annual cycles and use habitat. Understanding variation in migration strategy within and among species and individuals can be useful for understanding how birds navigate energetic trade-offs and designing or modifying conservation plans meant to benefit multiple species and life histories. We compared migration strategies among three migratory shorebird species with variable life history traits and short, medium, and long migration distances, respectively: American avocets (Recurvirostra americana), black-bellied plovers (Pluvialis squatarola), and Hudsonian godwits (Limosa haemastica). Avocets (short distance) exhibited the most within-species variation in migration duration, proportion of migration time spent at stopovers, and stopover duration. Plovers (medium distance) and godwits (long distance) showed less variation in these metrics, but godwits showed the most variation in the number of stopovers used. There were significant differences among species in migration distance, number of stopovers used, proportion of time stopped over, departure and arrival dates, and migration duration, but not mean stopover duration. We also found that avocets spent more time stopped over relative to migration distance than plovers or godwits, indicating that avocets showed the most energy-minimizing strategy of the three species. Our findings set the stage for future work assessing the effects of climate change and land use on characteristics associated with different migration strategies for additional migratory species.
Effect of snow cover on the off-host survival of Dermacentor variabilis (Acari: Ixodidae) larvae
(Journal of Medical Entomology, 2024-01) Diyes, Chulantha P; Yunik, Matthew E M; Dergousoff, Shaun J; Chilton, Neil
The geographical range of the American dog tick, Dermacentor variabilis (Say), in Canada continues to expand northwards into areas with colder winter temperatures. Understanding what influences the off-host survival of D. variabilis over winter is important for predicting the northern distributional limit of this species. A field experiment was conducted to determine the effect of snow cover on the off-host survival of unfed D. variabilis larvae from a population situated near the northern distributional limit in Saskatchewan, Canada. Ticks were placed in tubes within 1 of 9 field enclosures (tickaria) in early fall. The 9 tickaria were divided into 3 equal treatment groups: no snow cover, natural snow cover (maximum depth of 25 cm) and extra snow cover (maximum depth of 32 cm). Tick survival was measured in mid-winter and in early spring (i.e., ~17 and ~26 wk after start of experiment). The results showed that snow cover had a significant impact on the relative humidity, but not temperature, in the tickaria. Larvae in tickaria with no snow cover had a higher mortality rate (27%) than larvae in tickaria with natural snow cover (6%) or extra snow cover (4%). Although snow cover enhanced off-host survival, many individuals were able to survive in sub-zero temperatures under leaf litter in the absence of continuous snow cover for a period of 108 days. These findings have implications for the construction of predictive models to determine the northern distributional limits of D. variabilis, a species that is an important vector of several pathogens.

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