Evaluating environmental DNA as a tool for detecting an amphibian pathogen using an optimized extraction method.

Environmental DNA (eDNA) detection is a valuable conservation tool that can be used to identify and monitor imperiled or invasive species and wildlife pathogens. Batrachochytrium pathogens are of global conservation concern because they are a leading cause of amphibian decline. While eDNA techniques have been used to detect Batrachochytrium DNA in the environment, a systematic comparison of extraction methods across environmental samples is lacking. In this study, we first compared eDNA extraction methods and found that a soil extraction kit (Qiagen PowerSoil) was the most effective for detecting Batrachochytrium dendrobatidis in water samples. The PowerSoil extraction had a minimum detection level of 100 zoospores and had a two- to four-fold higher detection probability than other commonly used extraction methods (e.g., QIAamp extraction, DNeasy+Qiashredder extraction method, respectively). Next, we used this extraction method on field-collected water and sediment samples and were able to detect pathogen DNA in both. While field-collected water filters were equivalent to amphibian skin swab samples in detecting the presence of pathogen DNA, the seasonal patterns in pathogen quantity were different between skin swabs and water samples. Detection rate was lowest in sediment samples. We also found that detection probability increases with the volume of water filtered. Our results indicate that water filter eDNA samples can be accurate in detecting pathogen presence at the habitat scale but their utility for quantifying pathogen loads in the environment appears limited. We suggest that eDNA techniques be used for early warning detection to guide animal sampling efforts.

Intermittent Administration of Haloperidol after Cortical Impact Injury Neither Impedes Spontaneous Recovery Nor Attenuates the Efficacy of Environmental Enrichment.

The administration of haloperidol (HAL) once-daily for 19 days after experimental traumatic brain injury (TBI) impedes recovery and attenuates the efficacy of environmental enrichment (EE). However, it is unknown how intermittent administration of HAL affects the recovery process when paired with EE. Addressing the uncertainty is relevant because daily HAL is not always warranted to manage TBI-induced agitation in the clinic, and indeed intermittent therapy may be a more common approach. Hence, the aim of the study was to test the hypothesis that intermittent HAL would neither impair recovery in standard (STD)-housed controls nor attenuate the efficacy of EE. Anesthetized adult male rats received a cortical impact or sham injury and then were housed in STD or EE conditions. Beginning 24 h later, HAL (0.5 mg/kg; intraperitoneally [i.p.]) was administered either once-daily for 19 days or once every other day, whereas vehicle (VEH; 1 mL/kg; i.p.) was administered once daily. Motor performance and cognition were assessed on post-injury days 1-5 and 14-19, respectively. Cortical lesion volume was quantified on day 21. SHAM controls performed better than all TBI groups on motor and spatial learning [p < 0.05], but did not differ from the TBI + EE + daily VEH group on memory retention [p > 0.05]. The TBI + EE + daily VEH and TBI + EE + intermittent HAL groups did not differ from one another on beam-walk or spatial learning [p > 0.05], and both performed better than all other TBI groups [p < 0.05]. In contrast, the TBI + STD + daily HAL group performed worse than all TBI groups on spatial learning [p < 0.05]. No difference in any endpoint was revealed between the TBI + STD + intermittent HAL and TBI + STD + daily VEH groups [p > 0.05]. The results support the hypothesis that HAL is not detrimental when provided intermittently. If translatable to the clinic, intermittent HAL may be used to control TBI-induced agitation without negatively affecting spontaneous recovery or rehabilitative efficacy.