77 research outputs found
Pathogenic Neisseria Hitchhike on the Uropod of Human Neutrophils
Polymorphonuclear neutrophils (PMNs) are important components of the human innate immune system and are rapidly recruited at the site of bacterial infection. Despite the effective phagocytic activity of PMNs, Neisseria gonorrhoeae infections are characterized by high survival within PMNs. We reveal a novel type IV pilus-mediated adherence of pathogenic Neisseria to the uropod (the rear) of polarized PMNs. The direct pilus-uropod interaction was visualized by scanning electron microscopy and total internal reflection fluorescence (TIRF) microscopy. We showed that N. meningitidis adhesion to the PMN uropod depended on both pilus-associated proteins PilC1 and PilC2, while N. gonorrhoeae adhesion did not. Bacterial adhesion elicited accumulation of the complement regulator CD46, but not I-domain-containing integrins, beneath the adherent bacterial microcolony. Electrographs and live-cell imaging of PMNs suggested that bacterial adherence to the uropod is followed by internalization into PMNs via the uropod. We also present data showing that pathogenic Neisseria can hitchhike on PMNs to hide from their phagocytic activity as well as to facilitate the spread of the pathogen through the epithelial cell layer
Limits and possibilities in the geolocation of humans using multiple isotope ratios (H, O, N, C) of hair from east coast cities of the USA
NoWe examined multiple natural abundance isotope ratios of human
hair to assess biological variability within and between geographic
locations and, further, to determine how well these isotope values
predict location of origin. Sampling locations feature differing
seasonality and mobile populations as a robust test of the
method. Serially-sampled hair from Cambridge, MA, USA, shows
lower δ2 H and δ18 O variability over a one-year time course than
model-predicted precipitation isotope ratios, but exhibits
considerable differences between individuals. Along a ∼13° northsouth transect in the eastern USA (Brookline, MA, 42.3 ° N, College
Park, MD, 39.0 ° N, and Gainesville, FL, 29.7 ° N) δ18 O in human
hair shows relatively greater differences and tracks changes in
drinking water isotope ratios more sensitively than δ2 H.
Determining the domicile of humans using isotope ratios of hair
can be confounded by differing variability in hair δ18 O and δ2 H
between locations, differential incorporation of H and O into this
protein and, in some cases, by tap water δ18 O and δ2 H that differ
significantly from predicted precipitation values. With these
caveats, randomly chosen people in Florida are separated from
those in the two more northerly sites on the basis of the natural
abundance isotopes of carbon, nitrogen, hydrogen, and oxygen.This work was partially supported by the National Geospatial Agency under grant [HM1582-08-0024].Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring
Frontiers, 11–15 May 2015, Vienna, Austri
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