Research Publications (Food Safety)

Polymicrobial infections threaten the health of humans and animals but remain understudied in natural systems. We recently described the Pacific Oyster Mortality Syndrome (POMS), a polymicrobial disease affecting oyster production worldwide. In the French Atlantic coast, the disease involves coinfection with ostreid herpesvirus 1 (OsHV-1) and virulent Vibrio.

Proceedings of the National Academy of Sciences, Volume 119, Issue 33, August 2022. The type III secretion system (T3SS) encoded in the Salmonella pathogenicity island 1 (SPI-1) is a primary virulence factor for Salmonella, required for initiating the inflammatory diarrhea that is the hallmark of salmonellosis and for invading the intestinal epithelium, leading to potentially lethal systemic infection.

Proceedings of the National Academy of Sciences, Volume 119, Issue 17, April 2022. The bacterial pathogen Yersinia pestis gave rise to devastating outbreaks throughout human history, and ancient DNA evidence has shown it afflicted human populations as far back as the Neolithic. Y.

Staphylococcus aureus is a foremost bacterial pathogen responsible for a vast array of human diseases. Staphylococcal superantigens (SAgs) constitute a family of exotoxins from S. aureus that bind directly to major histocompatibility complex (MHC) class II and T cell receptors to drive extensive T cell activation and cytokine release. Although...

Domoic acid (DA), the causative agent of amnesic shellfish poisoning, is produced by select organisms within two distantly related algal clades: planktonic diatoms and red macroalgae. The biosynthetic pathway to isodomoic acid A was recently solved in the harmful algal bloom–forming diatom Pseudonitzschia multiseries, establishing the genetic basis for the...

Early life exposure to environmental lead (Pb) has been linked to decreased IQ, behavior problems, lower lifetime earnings, and increased criminal activity. Beginning in the 1970s, limits on Pb in paint, gasoline, food cans, and regulated water utilities sharply curtailed US environmental Pb exposure. Nonetheless, hundreds of thousands of US...

Gram-positive organisms with their thick envelope cannot be lysed by complement alone. Nonetheless, antibody-binding on the surface can recruit complement and mark these invaders for uptake and killing by phagocytes, a process known as opsonophagocytosis. The crystallizable fragment of immunoglobulins (Fcγ) is key for complement recruitment. The cell surface of...

The long charge carrier lifetime of the hybrid organic–inorganic perovskites (HOIPs) is the key for their remarkable performance as a solar cell material. The microscopic mechanism for the long lifetime is still in debate.

We consider epidemiological modeling for the design of COVID-19 interventions in university populations, which have seen significant outbreaks during the pandemic. A central challenge is sensitivity of predictions to input parameters coupled with uncertainty about these parameters. Nearly 2 y into the pandemic, parameter uncertainty remains because of changes in...

Hemachromatosis (iron-overload) increases host susceptibility to siderophilic bacterial infections that cause serious complications, but the underlying mechanisms remain elusive. The present study demonstrates that oral infection with hyperyersiniabactin (Ybt) producing Yersinia pseudotuberculosis Δfur mutant (termed Δfur) results in severe systemic infection and acute mortality to hemochromatotic mice due to rapid...

COVID-19 remains a stark health threat worldwide, in part because of minimal levels of targeted vaccination outside high-income countries and highly transmissible variants causing infection in vaccinated individuals. Decades of theoretical and experimental data suggest that nonspecific effects of non–COVID-19 vaccines may help bolster population immunological resilience to new pathogens....

After binding to its cell surface receptor angiotensin converting enzyme 2 (ACE2), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the host cell through directly fusing with plasma membrane (cell surface pathway) or undergoing endocytosis traveling to lysosome/late endosome for membrane fusion (endocytic pathway). However, the endocytic entry regulation by...

The emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major concern given their potential impact on the transmissibility and pathogenicity of the virus as well as the efficacy of therapeutic interventions. Here, we predict the mutability of all positions in SARS-CoV-2 protein domains to...

Pacific Ocean tuna is among the most-consumed seafood products but contains relatively high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury levels vary in space and time, yet the drivers are not well understood. Here, we map mercury concentrations in skipjack tuna across the Pacific Ocean and build generalized additive models to quantify the anthropogenic, ecological, and biogeochemical drivers.

Hemachromatosis (iron-overload) increases host susceptibility to siderophilic bacterial infections that cause serious complications, but the underlying mechanisms remain elusive. The present study demonstrates that oral infection with hyperyersiniabactin (Ybt) producing Yersinia pseudotuberculosis Δfur mutant (termed Δfur) results in severe systemic infection and acute mortality to hemochromatotic mice due to rapid...

Coxiella burnetii is a bacterial pathogen that replicates within host cells by establishing a membrane-bound niche called the Coxiella-containing vacuole. Biogenesis of this compartment requires effectors of its Dot/Icm type IV secretion system. A large cohort of such effectors has been identified, but the function of most of them remain...

Anthropogenic activities have led to widespread contamination with mercury (Hg), a potent neurotoxin that bioaccumulates through food webs. Recent models estimated that, presently, 200 to 600 t of Hg is sequestered annually in deep-sea sediments, approximately doubling since industrialization. However, most studies did not extend to the hadal zone (6,000-...

The protein MakA was discovered as a motility-associated secreted toxin from Vibrio cholerae. Here, we show that MakA is part of a gene cluster encoding four additional proteins: MakB, MakC, MakD, and MakE. MakA, MakB, and MakE were readily detected in culture supernatants of wild-type V. cholerae, whereas secretion was very much reduced from a flagellum-deficient mutant.

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder characterized by the loss of nigrostriatal dopaminergic neurons. Mounting evidence suggests that Nrf2 is a promising target for neuroprotective interventions in PD. However, electrophilic chemical properties of the canonical Nrf2-based drugs cause irreversible alkylation of cysteine residues on cellular proteins resulting...

Cadmium is an environmental pollutant and significant health hazard that is similar to the physiological metal zinc. In Caenorhabditis elegans, high zinc homeostasis is regulated by the high zinc activated nuclear receptor (HIZR-1) transcription factor. To define relationships between the responses to high zinc and cadmium, we analyzed transcription.

Cellular ionic concentrations are a central factor orchestrating host innate immunity, but no pathogenic mechanism that perturbs host innate immunity by directly targeting metal ions has yet been described. Here, we report a unique virulence strategy of Yersinia pseudotuberculosis (Yptb) involving modulation of the availability of Mn2+, an immunostimulatory metal...

EmrE is an Escherichia coli multidrug efflux pump and member of the small multidrug resistance (SMR) family that transports drugs as a homodimer by harnessing energy from the proton motive force. SMR family transporters contain a conserved glutamate residue in transmembrane 1 (Glu14 in EmrE) that is required for binding...

Among the organisms that spread into and flourish in Arctic waters with rising temperatures and sea ice loss are toxic algae, a group of harmful algal bloom species that produce potent biotoxins. Alexandrium catenella, a cyst-forming dinoflagellate that causes paralytic shellfish poisoning worldwide, has been a significant threat to human health in southeastern Alaska for centuries.

Listeriolysin S (LLS) is a thiazole/oxazole–modified microcin (TOMM) produced by hypervirulent clones of Listeria monocytogenes. LLS targets specific gram-positive bacteria and modulates the host intestinal microbiota composition. To characterize the mechanism of LLS transfer to target bacteria and its bactericidal function, we first investigated its subcellular distribution in LLS-producer bacteria....

Pathogen emergence is a complex phenomenon that, despite its public health relevance, remains poorly understood. Vibrio vulnificus, an emergent human pathogen, can cause a deadly septicaemia with over 50% mortality rate. To date, the ecological drivers that lead to the emergence of clinical strains and the unique genetic traits that allow these clones to colonize the human host remain mostly unknown.