skip to main content

Title: Chronic repeated exposure to weather-related stimuli elicits few symptoms of chronic stress in captive molting and non-molting European starlings ( Sturnus vulgaris )
 ;  ;  
Publication Date:
Journal Name:
Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
Page Range or eLocation-ID:
493 to 503
Wiley Blackwell (John Wiley & Sons)
Sponsoring Org:
National Science Foundation
More Like this
  1. Engineered nanoparticles are incorporated into numerous emerging technologies because of their unique physical and chemical properties. Many of these properties facilitate novel interactions, including both intentional and accidental effects on biological systems. Silver-containing particles are widely used as antimicrobial agents and recent evidence indicates that bacteria rapidly become resistant to these nanoparticles. Much less studied is the chronic exposure of bacteria to particles that were not designed to interact with microorganisms. For example, previous work has demonstrated that the lithium intercalated battery cathode nanosheet, nickel manganese cobalt oxide (NMC), is cytotoxic and causes a significant delay in growth of Shewanella oneidensis MR-1 upon acute exposure. Here, we report that S. oneidensis MR-1 rapidly adapts to chronic NMC exposure and is subsequently able to survive in much higher concentrations of these particles, providing the first evidence of permanent bacterial resistance following exposure to nanoparticles that were not intended as antibacterial agents. We also found that when NMC-adapted bacteria were subjected to only the metal ions released from this material, their specific growth rates were higher than when exposed to the nanoparticle. As such, we provide here the first demonstration of bacterial resistance to complex metal oxide nanoparticles with an adaptation mechanismmore »that cannot be fully explained by multi-metal adaptation. Importantly, this adaptation persists even after the organism has been grown in pristine media for multiple generations, indicating that S. oneidensis MR-1 has developed permanent resistance to NMC.« less
  2. Fibrotic disorders account for over one third of mortalities worldwide. Despite great efforts to study the cellular and molecular processes underlying fibrosis, there are currently few effective therapies. Dual-stage polymerization reactions are an innovative tool for recreating heterogeneous increases in extracellular matrix (ECM) modulus, a hallmark of fibrotic diseases in vivo . Here, we present a clickable decellularized ECM (dECM) crosslinker incorporated into a dynamically responsive poly(ethylene glycol)-α-methacrylate (PEGαMA) hybrid-hydrogel to recreate ECM remodeling in vitro . An off-stoichiometry thiol–ene Michael addition between PEGαMA (8-arm, 10 kg mol −1 ) and the clickable dECM resulted in hydrogels with an elastic modulus of E = 3.6 ± 0.24 kPa, approximating healthy lung tissue (1–5 kPa). Next, residual αMA groups were reacted via a photo-initiated homopolymerization to increase modulus values to fibrotic levels ( E = 13.4 ± 0.82 kPa) in situ . Hydrogels with increased elastic moduli, mimicking fibrotic ECM, induced a significant increase in the expression of myofibroblast transgenes. The proportion of primary fibroblasts from dual-reporter mouse lungs expressing collagen 1a1 and alpha-smooth muscle actin increased by approximately 60% when cultured on stiff and dynamically stiffened hybrid-hydrogels compared to soft. Likewise, fibroblasts expressed significantly increased levels of the collagen 1a1more »transgene on stiff regions of spatially patterned hybrid-hydrogels compared to the soft areas. Collectively, these results indicate that hybrid-hydrogels are a new tool that can be implemented to spatiotemporally induce a phenotypic transition in primary murine fibroblasts in vitro .« less