McGill Science Undergraduate Research Journal

Effects of Electrical Stimulation on Germination and Early Seedling Growth in Zea mays subsp. mays

Bryan-Eli Khoury — Fri, 10 Apr 2026 00:00:00 -0400

Early seedling establishment is increasingly important for agricultural resilience. Electrical stimulation has been proposed as a low-cost approach to modulate plant signalling pathways and potentially improve germination and early growth. This study tested whether brief daily electrical stimulation affects germination success and early seedling growth in Zea mays subsp. mays.

Pre-soaked Zea mays subsp. mays seeds were distributed into five groups (0 V, 3 V, 6 V, 9 V, 12 V; 35 seeds per group; total n=175). Electrical stimulation was applied for 10 min daily over 5 consecutive days using battery power sources and alligator clip electrodes placed diagonally across each tray on a moistened paper substrate. Germination was defined by visible root emergence (with or without shoot emergence). After 5 days, shoot and root lengths were measured, and group means were compared using one-way ANOVA.

Germination percentages were similar across treatments (45.71-54.29%), with no clear voltage-dependent trend. Mean shoot length was highest at 6 V (1.20 cm; SD=0.97) but did not differ significantly across voltages (ANOVA p=0.410). Mean root length peaked at 6 V (2.00 cm; SD=1.34) and decreased at higher voltages (e.g., 12 V: 1.10 cm; SD=0.85), with voltage producing a significant effect on root length (ANOVA p=0.014).

Interpretation is limited by the short duration (5 days) and substantial non-germination, which reduced effective sample size and statistical power. Growth on a nutrient-free paper substrate may limit generalizability to soil conditions, and results may be influenced by variability in delivered voltage (battery drift/electrode placement) and by measurement error from bent or branching roots.

Electrical stimulation did not improve germination, but moderate stimulation (6 V) was associated with enhanced early root elongation, while shoot growth differences were not significant. These findings suggest that appropriately tuned electrical stimulation may selectively enhance early root development in maize seedlings, warranting longer-term studies assessing downstream effects on plant performance and yield.

Species Composition and Morphological Variation of Crayfish in the Gault Nature Reserv

Corinne Lapierre, Marlee Bickerdike, Kate Healy, Karim Chehata — Fri, 10 Apr 2026 00:00:00 -0400

Crayfish play a crucial role as ecosystem engineers in freshwater ecosystems, yet they remain poorly represented in ecological studies. Integrating aquatic invertebrates into biodiversity monitoring efforts is urgentlyneeded, particularly given their important ecological role as indicators of freshwater ecosystem health. The purpose of this pilot study was to record crayfish presence in the Gault Nature Reserve and to characterize species identity, morphology, and dorsal colouration of individuals from two habitats sampled (Lake Hertel and a nearby stream), with colouration assessed for substrate matching. This study records the occurrence of two crayfish species in the Gault Nature Reserve of McGill University and examines their morphological and colouration differences. Two species of crayfish were identified: the Virile crayfish (Faxonius virilis) in Lake Hertel and the Appalachian Brook crayfish (Cambarus bartonii) in a nearby stream. A key outcome of this pilot survey is the identification of different crayfish species living in different habitat types within the reserve. This finding demonstrates the necessity of broader biodiversity surveys of freshwater species in Gault. Morphometric analyses showed significant size differences between species aligning with ecological differences observed between the two site-specific species, though these disparities likely reflect species–specific traits more than habitat effects alone, which could not be isolated in this study design. Colouration analyses did not support the hypothesis that crayfish colouration matches substrate colours for camouflage. The analysis of colouration is considered exploratory and must not be considered a conclusive test of substrate matching because of the failure of photographic colour extraction to match colouration and the absence of consideration of body size sex, and developmental stages. Future research should incorporate more controlled colour assessments, expand the survey area, and conduct genetic analyses and transplant experiments to clarify whether colouration and morphology are determined by environmental or genetic factors.

Time-independent perturbation theory: degeneracy lifted to the second order

Juan Álvarez Ruiz, Meijian Li — Fri, 10 Apr 2026 00:00:00 -0400

Although the fundamental principles of time-independent perturbation theory are well-established and widely applied, the specific treatment of degeneracy lifted to the second order remains largely unexplored. This work fills the gap by presenting a systematic derivation of time-independent perturbation theory that accounts for the added complexity introduced by non-trivial degeneracies. We provide a general procedure and corresponding formulae for calculating state and energy corrections to any order, with degeneracy lifted to the second order. Additionally, we apply these formulae to solve a prototype problem of the dressed quark system. This work not only advances the theoretical framework but also provides practical tools for tackling complex problems in quantum physics.

Spatial Modeling of Canadian Boreal Peatland Carbon Sinks

Sophie Piret, Quinn Saul, Simone Châtelier — Fri, 10 Apr 2026 00:00:00 -0400

Abstract

Peatlands are among the most effective carbon sinks, yet their stability is increasingly threatened by expanding land use and infrastructure. Spatially explicit information remains limited on where Canada’s boreal peatlands combine high CO₂ sink capacity with low human pressure. We mapped growing-season CO₂ sink potential across boreal peatlands and identified candidate conservation areas with strong CO₂ uptake and low human disturbance using widely available climate data. We used AmeriFlux eddy-covariance data from four Canadian boreal peatland flux-tower sites (2007–2019) to model climatic controls on net ecosystem exchange (NEE) of CO₂ and upscale predictions with ERA5-Land reanalysis data. A pooled multiple linear regression using air temperature, subsurface soil temperature (28–100 cm), and incoming shortwave radiation explained 57% of NEE variability (adjusted R²=0.57; RMSE=0.36 μmol CO₂ m⁻² s⁻¹). Comparisons of tower-measured and ERA5-Land climatic variables showed strong agreement for shortwave radiation and modest temperature biases, highlighting uncertainty in regional upscaling. Applying the fitted model across boreal peatlands predicted the strongest sinks in the Northwest Territories and weaker sinks toward the northern boreal margin and mountainous regions. We derived Predicted Carbon Sink Strength (PCSS) by weighting predicted NEE by peatland fractional cover and setting CO₂ sources to zero to emphasize strong sink potential in areas with high peatland cover. Finally, we combined PCSS with an inverted Human Footprint (IHFP) layer to construct a Boreal Peatland Conservation Index (BPCI) that supports conservation prioritization by highlighting low-disturbance areas with high predicted sink strength. High-scoring regions were concentrated in the Hudson Bay Lowlands and the Northwest Territories. Because predictions are based on four flux-tower sites and represent growing-season CO₂ exchange, results are best interpreted as screening-level guidance. Overall, this integrative framework provides an interpretable, updatable approach to identify boreal peatland regions where protecting CO₂ sinks may deliver high climate benefits with low development conflict.

Positive Selection on MAMLD1 Gene Human Lineage Suggests Pleiotropic Adaptation During Evolution

Yunhua Ren — Fri, 10 Apr 2026 00:00:00 -0400

Gene regulatory factors (GRFs) are essential regulators of human phenotypic diversity. Among these, MAMLD1 acts as a transcriptional co-activator critical for male genital development. Mutations in MAMLD1 are clinically associated with X-linked hypospadias type 2, a condition that alters the placement of the male urethral opening and potentially impacts reproductive fitness. In evolutionary biology, natural selection is often detected by comparing the rates of non-synonymous (dN) and synonymous (dS) substitutions (ω = dN/dS). Positive selection (ω > 1) represents the rapid fixation of beneficial mutations that enhance an organism’s fitness, distinguishing it from purifying selection (ω < 1), which removes deleterious mutations, and neutral evolution (ω = 1), which involves random genetic drift. Building upon broader genomic surveys, this study provides a high-resolution analysis of MAMLD1 using the PAML v4.9 suite across 20 primate species. By employing site models to assess selection across the primate phylogeny, we identified significant signals of positive selection. Findings suggest that MAMLD1 has undergone adaptive evolution, likely driven by sexual selection and its role in reproductive isolation. This research underscores the gene's multifaceted role in shaping human-specific developmental phenotypes and evolutionary strategies.

Personality and Wellbeing: How Conscientiousness and Openness Influence Wellbeing Through Intrinsic and Extrinsic Goal Aspirations and Attainment

Georgia Roberts — Fri, 10 Apr 2026 00:00:00 -0400

Well-being is a major focus of psychological research worldwide. Although environmental factors, personality traits, and goal achievement each predict well-being, they are often examined in isolation. However, it remains unclear how these factors are connected, for example, whether personality influences well-being in part through its impact on goal setting and goal attainment. The present study examines whether conscientiousness and openness relate to well-being through goal aspirations and goal attainment. Guided by Self-Determination Theory, intrinsic and extrinsic goals were tested as mediating pathways connecting conscientiousness and openness to well-being. Using data from 1,892 adults across 51 countries, multiple mediation analyses showed that both conscientiousness and openness were positively associated with well-being. Conscientiousness predicted greater intrinsic goal importance and intrinsic goal attainment, which partially mediated its relationship with well-being. Conscientiousness also negatively predicted extrinsic goal importance. Openness strongly predicted intrinsic goal importance and attainment, while negatively predicting extrinsic goals. The association between openness and well-being was fully mediated by intrinsic goal attainment. Extrinsic goal importance and attainment were not significantly related to well-being. Overall, these findings highlight intrinsic goal pursuit as a key psychological mechanism through which personality traits impact well-being.

Stewart Physicochemical Interpretation of Cerebrospinal Fluid Acid--Base Physiology in Critical Illness

Samuel Qu — Fri, 10 Apr 2026 00:00:00 -0400

Cerebrospinal fluid (CSF) constitutes the physicochemical milieu bathing the brain and brainstem and can diverge from arterial blood in both magnitude and time course during critical illness. This review synthesizes human and experimental evidence relevant to a Stewart physicochemical interpretation of CSF acid-base physiology, emphasizing compartmental kinetics, blood–CSF barrier and choroid plexus transport, and methodological constraints that complicate measurement. Because CSF contains minimal weak-acid buffering under physiological conditions, CSF pH is often dominated by PCO2 and strong ion difference (SID), making CSF a tractable compartment for compartment-aware physicochemical reasoning. Classical clinical observations and modern simultaneous CSF–arterial datasets in pregnancy and aneurysmal subarachnoid hemorrhage illustrate paired shifts in SID and PCO2 that are not inferable from arterial blood gases alone. Transporter-dependent recovery from hypercapnia, pH-sensitive ion fluxes, and chloride-linked transport perturbation studies support that CSF acid-base homeostasis is actively regulated and plausibly vulnerable in neuroinflammation and brain injury. We outline ICU implications, focusing on why arterial normalization may not ensure central normalization and why time-resolved ventricular datasets are the key prerequisite for bedside translation.

Effects of Candida albicans-derived Farnesol and Tyrosol on Quorum-Sensing Pathways in Pseudomonas aeruginosa Biofilms: Implication for Antimicrobial Resistance

Bianka Dusseault — Fri, 10 Apr 2026 00:00:00 -0400

In 2017, amid an antimicrobial crisis, the World Health Organization classified Pseudomonas Aeruginosa as a priority pathogen for the Research and Development of new antibiotics. P. aeruginosa’s ability to form biofilms–structured aggregation of microcolonies embedded in a self-generated matrix–and regulate virulence through quorum-sensing (QS) often results in antibiotic failure, especially in nosocomial settings. As synthetic antibiotics have become increasingly ineffective in eradicating P. aeruginosa biofilm, chronic infections persist in cystic fibrosis and burn wound patients. This review investigates C.albicans-derived molecules, tyrosol, and farnesol, as potential quorum-sensing inhibitors (QSIs) of P. aeruginosa QS circuits (LasI/LasR, RhlI/RhIR, and PQS) in single-species biofilms. These fungal-derived compounds have been shown to have anti-biofilm and antibacterial activity by disrupting P. aeruginosa QS pathways and modulating virulence factor expression. In combinatorial therapeutics, tyrosol and farnesol have been demonstrated to facilitate certain antibiotic activity, suggesting potential for clinical implementation. Unlike traditional antibiotics, C. albicans QSIs have co-evolved with P. aeruginosa and developed inhibition mechanisms that minimize the selective pressures driving antimicrobial resistance. By targeting cell-to-cell communication rather than bacterial growth, tyrosol and farnesol offer a propitious avenue for P. aeruginosa biofilms-associated infections. However, as this remains an emerging field of research in the context of P. aeruginosa-driven infections, further research is needed to determine clinical plausibility, especially in in-vivo models, to understand specific mechanisms of action, dosage optimization and potential undesirable off-target interactions.

Engineering Safety in Childhood Bone Fragility

Evelyn Huaman, Pierre Demerjian — Fri, 10 Apr 2026 00:00:00 -0400