Danilo S. Boskovic

Neutrophils present the host’s first line of defense against bacterial infections. These immune effector cells are mobilized rapidly to destroy invading pathogens by (a) reactive oxygen species (ROS)-mediated oxidative bursts and (b) via phagocytosis. In addition, their antimicrobial service is capped via a distinct cell death mechanism, by the release of their own decondensed nuclear DNA, supplemented with a variety of embedded proteins and enzymes. The extracellular DNA meshwork ensnares the pathogenic bacteria and neutralizes them. Such neutrophil extracellular DNA traps (NETs) have the potential to trigger a hemostatic response to pathogenic infections. The web-like chromatin serves as a prothrombotic scaffold for platelet adhesion and activation. What is less obvious is that platelets can also be involved during the initial release of NETs, forming heterotypic interactions with neutrophils and facilitating their responses to pathogens. Together, the platelet and neutrophil responses can effectively localize an infection until it is cleared. However, not all microbial infections are easily cleared. Certain pathogenic organisms may trigger dysregulated platelet–neutrophil interactions, with a potential to subsequently propagate thromboinflammatory processes. These may also include the release of some NETs. Therefore, in order to make rational intervention easier, further elucidation of platelet, neutrophil, and pathogen interactions is still needed.

Although heavy metal concentrations naturally vary in the environment, anthropogenic sources of heavy metals can mask and override such fluctuations. Indicator species can be used to determine environmental concentrations of certain metals and evaluate the impacts of metals from associated anthropogenic sources. We sought to determine if the hermit crab Pagurus samuelis (Stimpson, 1857) may play a role as an indicator species along the Southern California coast. Seawater and P. samuelis samples were collected from both Cabrillo Beach and White Point Beach rocky intertidal locations and analyzed for concentrations of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) using microwave plasma-atomic emission spectrometry (MP-AES). Lead concentrations were higher in seawater at Cabrillo Beach compared to White Point Beach, whereas Zn concentrations were higher at White Point Beach than at Cabrillo Beach. All other metals were not significantly different between these locations. Cd was higher in hermit crabs collected from Cabrillo Beach than those from White Point Beach, whereas Cr was higher in crabs collected from White Point Beach compared with those from Cabrillo Beach. In comparisons of seawater with samples of hermit crabs, seawater had higher concentrations of Zn and Cd, whereas hermit crabs had higher concentrations of Cu at both locations, and higher levels of Cr at White Point Beach. While this study does not provide conclusive evidence that P. samuelis is an indicator species, it does demonstrate differences in metal concentrations between tested locations and populations of P. samuelis. Although P. samuelis may not be negatively impacted by the heavy metal concentrations we found, the risks of potential bioaccumulation at higher trophic levels is of concern.