High parasite diversity maintained after an alga-virus coevolutionary arms race.

Arms race dynamics are a common outcome of host-parasite coevolution. While they can theoretically be maintained indefinitely, realistic arms races are expected to be finite. Once an arms race has ended, for example due to the evolution of a generalist-resistant host, the system may transition into coevolutionary dynamics that favour long-term diversity. In microbial experiments, host-parasite arms races often transition into a stable coexistence of generalist-resistant hosts, (semi-)susceptible hosts, and parasites. While long-term host diversity is implicit in these cases, parasite diversity is usually overlooked. In this study, we examined parasite diversity after the end of an experimental arms race between a unicellular alga (Chlorella variabilis) and its lytic virus (PBCV-1). First, we isolated virus genotypes from multiple time points from two replicate microcosms. A time-shift experiment confirmed that the virus isolates had escalating host ranges, i.e., that arms races had occurred. We then examined the phenotypic and genetic diversity of virus isolates from the post-arms race phase. Post-arms race virus isolates had diverse host ranges, survival probabilities, and growth rates; they also clustered into distinct genetic groups. Importantly, host range diversity was maintained throughout the post-arms race phase, and the frequency of host range phenotypes fluctuated over time. We hypothesize that this dynamic polymorphism was maintained by a combination of fluctuating selection and demographic stochasticity. Together with previous work in prokaryotic systems, our results link experimental observations of arms races to natural observations of long-term host and parasite diversity.

COVID-19 Emergency Restrictions on Firearms.

This article examines emergency restrictions imposed by state-level public officials on firearms during the COVID-19 pandemic. It surveys the litigation challenging each of the relatively few restrictions that were imposed, considers when and whether courts should apply the deferential Jacobson standard, the Heller Second Amendment analysis, or both, and explores the possibility that the unsettled nature of Second Amendment jurisprudence makes it likely that challenges to emergency firearms restrictions could result in dramatic developments in what the Second Amendment protects.

Implementing Checklists to Improve Police Responses to Co-Victims of Gun Violence.

This qualitative study identifies police interactions with gun violence co-victims as a crucial, overlooked component of police unresponsiveness, particularly in minority communities where perceptions of police illegitimacy and legal estrangement are relatively high. Gun violence co-victims in three cities participated in online surveys, in which they described pervasive disregard by police in the aftermath of their loved ones' shooting victimization. We build on the checklist model that has improved public safety outcomes in other complex, high-intensity professional contexts to propose a checklist for police detectives to follow in the aftermath of gun violence. To build the checklist, we also reviewed the general orders of five police departments to better understand what guidance, if any, is currently given to police personnel regarding how they should interact with gun violence victims.

Biliary reconstruction is enhanced with a collagen-polyethylene glycol sealant.

Bile leaks occur in up to 27 per cent of liver transplant patients after biliary reconstruction. Synthetic sealants have not been investigated for these biliary procedures. We performed a randomized controlled study to evaluate a novel absorbable polyethylene glycol/collagen biopolymer sealant (CT3 Surgical Sealant) after incomplete end-to-end choledochocholedochostomy (CDCD) in pigs. Pigs (n = 18) underwent transection of the common bile duct and incomplete CDCD over a T-tube, leaving a one-sixth circumferential defect anteriorly. Animals were randomly assigned to treatment (CDCD with sealant, n = 9) or control (no sealant, n = 9). Drains were used to monitor leak volume and bilirubin (bili) concentration. Cholangiography was performed on postoperative day 3. Leaks were defined as drain bili/serum bill > 3, total drain output > 10 mL/kg, and/or extravasation on cholangiography. Animals sacrificed at 3 and 8 weeks (n = 4 and n = 5 from each group, respectively) underwent pathologic examination of the CDCD site. Statistical methods included Student's t test, chi2, linear regression, and analysis of variance procedures. The control group had a higher drain output rate over the first 4 postoperative days than the treatment group (P < 0.05, analysis of variance). Five of nine (56%) control and one of nine (11%) treatment animals had a bile leak (P < 0.05, chi2). There was no major inflammatory response to the sealant versus controls. We conclude that CT3 is effective in decreasing biliary leaks in an incomplete CDCD porcine model with no major adverse pathologic changes. This sealant should be considered for trials for biliary reconstruction in humans.