ScholarWorks@UMassAmherst

Recent Submissions

  • Publication
    Environmental justice beyond race: Skin tone and exposure to air pollution
    (2025) Cardenas, Juan-Camilo; Gomez, Sandra Aguilar; Diaz, Ricardo Salas
    Recent research, focused mostly on the United States and Western Europe, shows that marginalized communities often face greater environmental degradation. However, the ethnoracial categories used in these studies may not fully capture environmental inequality in the Global South. Moving beyond conventional ethnoracial variables, this study presents findings exploring the link between skin tone and fine particulate matter (PM2.5) exposure in Colombia. By matching household geolocations from a large-scale longitudinal survey with satellite-based PM2.5 estimates, we find that skin tone predicts both initial pollution exposure levels and their changes over time. Although average exposure levels remained stable during our study period, the environmental justice (EJ) landscape in Colombia contemporaneously underwent a complete transformation. In 2010, lighter-skinned individuals faced higher PM2.5 exposure, but darker-skinned individuals experienced steeper increases in the following years. By 2016, the EJ gap had reversed, with people with the darkest skin tones exposed to PM2.5 levels nearly one SD higher than those faced by people with the lightest skin tones. These patterns remain robust when controlling for a comprehensive set of theoretically relevant covariates, including ethnoracial self-identification and income. Disproportionate exposure to pollution from fires partially explains the observed disparities. Decomposition analysis shows that this variable, local collective action, and economic marginalization account for a sizeable share of the EJ gap. However, one-third of the gap remains unexplained by observable characteristics. With climate change intensifying fire incidence, the disproportionate disease burdens that vulnerable groups face might deepen unless policy measures are taken to reverse this trend.
  • Publication
    Dynamics of a von Willebrand Factor A1 Autoinhibitory Module with O-Linked Glycans and Its Roles in Regulation of GPIbα Binding
    (2025) Zhang, Xiaohui (Frank); Cao, Yiwei; Im, Wonpil
    The von Willebrand factor (VWF), a multimeric plasma glycoprotein, binds to the platelet glycoprotein (GPIb alpha) to initiate the process of primary hemostasis as a response to blood flow alteration in the site of vascular injury. The GPIb alpha binding site located on the A1 domain of VWF is exposed during the activation of the VWF multimer when it changes from a coiled form to a thread-like, extended form. Though experimental studies have demonstrated that the autoinhibitory module (AIM) connected to the N-/C-termini of the A1 domain is a regulator of VWF activity, the molecular mechanism underlying the regulation of A1-GPIb alpha binding remains unclear. We modeled the structures of the A1 domain having full-length N-terminal AIM (NAIM) and C-terminal AIM (CAIM) with different types of O-linked glycans. The conventional and steered molecular dynamics simulations were conducted to investigate the dynamics of the AIM and O-glycans under different conditions and elucidate how they affect the binding of GPIb alpha. Our results indicate that the NAIM alone with no glycan is sufficient to shield the GPIb alpha binding site under static conditions. However, when the AIM is unfolded with external forces applied, the O-glycans on both NAIM and CAIM increase the shielding of the binding site. These findings suggest a potential mechanism by which the AIM and O-glycans regulate the interaction of the VWF A1 domain and GPIb alpha.
  • Publication
    Constitutive heterochromatin controls nuclear mechanics, morphology, and integrity through H3K9me3 mediated chromocenter compaction
    (2025) Stephens, Andrew; Manning, Gianna; Li, Andy; Eskndir, Nebiyat; Currey, Marilena
    Aberrant nuclear morphology is a hallmark of human disease and causes nuclear dysfunction. Perturbed nuclear mechanics via reduced heterochromatin weakens the nucleus resulting in nuclear blebbing and rupture. While the role of heterochromatin is known, the separate roles of constitutive heterochromatin methylation states remains elusive. Using MEF and HT1080 cells, we isolated the individual contribution of constitutive heterochromatin H3K9 methylation states through histone methyltransferase inhibitors. Inhibition of SUV39H1 via Chaetocin downregulates H3K9 trimethylation (me3), while inhibition of G9a via BIX01294 downregulates H3K9 dimethylation (me2). Overall, the loss of H3K9me3 increased nuclear blebbing and rupture in interphase nuclei due to decreased nuclear rigidity from decompaction of chromocenters. Oppositely, loss of H3K9me2 decreased nuclear blebbing and rupture with increased nuclear rigidity and more compact chromocenters. We show that facultative heterochromatin and HP1 alpha are non-essential for chromocenter compaction. Constitutive heterochromatin provides essential nuclear mechanical support to maintain nuclear shape and integrity through chromocenter compaction.
  • Publication
    Electric spiking activity in epithelial cells
    (2025) Yu, Sunmin; Granick, Steve
    Epithelial cells (human keratinocyte cells and the canine MDCK cell line), traditionally viewed as electrically non-self-excitable and involved primarily in physiological functions such as barrier presentation, absorption, secretion, and protection, are shown here to exhibit traveling extracellular electric charge when they recover from spatially focused, laser-induced wounding of confluent monolayers cultured on a multielectrode array chip. Voltage spikes measured on these electrodes display depolarization, repolarization, and hyperpolarization phases with amplitudes similar to the action potentials of neurons but with the markedly slower duration of 1 to 2 s. Some propagate distances up to hundreds of mu m from the wound with a mean speed of around 10 mm s-1. Generation and transmission of bioelectric signals are significantly influenced by the perturbation of mechanosensitive cationic ion channels. These direct measurements confirm bioelectric signaling that previous work has hypothesized to regulate epithelial cell development and may have relevance to the frequency parameter selection of bioelectric devices.
  • Item
    Skilled mariner or nefarious pirate?: AI on the seas of OP and Social Justice
    (2025-03-04) Keohane, Catherine; Savage, Justin
    Collaborating in a national certificate program in open pedagogy (OP) confirmed our belief in the value of open practices to address social justice while also highlighting the challenges of ensuring that content creation and consumption truly addresses the needs of underrepresented groups. Intentionally done, open practices can serve what Lambert (2018) identifies as redistributive, recognitive, and representational justice. Unintentionally done, open practices can harm participants, burdening them with work or with the responsibility for surfacing the concerns of marginalized groups. As part of this program, we developed a research assignment for students that helped them develop a sense of authority and the ability to create and share knowledge. Our development process, however, revealed that separating the implications of AI from OP was increasingly impossible. With that in mind, we consider the various impacts of AI (ethical, environmental, financial) and how they can be reconciled with the tenets of social-justice-oriented OP.