Description: Disentangling the role that multiple interacting factors have on species responses to shifting climate poses a significant challenge. However, our ability to do so is of utmost importance to predict the effects of climate change on species distributions. We examined how populations of three species of wetland breeding amphibians, which varied in life history requirements, responded to a six-year period of extremely variable in precipitation. This interval was punctuated by both extensive drought and heavy precipitation and flooding, providing a natural experiment to measure community responses to environmental perturbations. We estimated occurrence dynamics using a discrete hidden Markov modeling approach that incorporated information regarding habitat state and predator-prey interactions. This approach allowed us to measure how metapopulation dynamics of each amphibian species was affected by interactions among weather, wetland hydroperiod, and co-occurrence with fish predators. The pig frog, a generalist, proved most resistant to perturbations, with both colonization and persistence being unaffected by seasonal variation in precipitation or co-occurrence with fishes. The ornate chorus frog, an ephemeral wetland specialist, responded positively to periods of drought owing to increased persistence and colonization rates during periods of low-rainfall. Low probabilities of occurrence of the ornate chorus frog in long-duration wetlands were driven by interactions with predators due to low colonization rates when fishes were present. The mole salamander was most sensitive to shifts in water availability. In our study area, this species never occurred in short-duration wetlands and persistence probabilities decreased during periods of drought. At the same time, negative effects occurred with extreme precipitation because flooding facilitated colonization of fishes to isolated wetlands and mole salamanders did not colonize wetlands once fishes were present. We demonstrate that the effects of changes in water availability depend on interactions with predators and wetland type and are influenced by the life history of each of our species. The dynamic species occurrence modeling approach we used offers promise for other systems when the goal is to disentangle the complex interactions that determine species responses to environmental variability. This article is protected by copyright. All rights reserved.

Description: Toll-like receptor 9 antagonizes antibody affinity maturation Toll-like receptor 9 antagonizes antibody affinity maturation, Published online: 23 February 2018; doi:10.1038/s41590-018-0052-z The presentation of antigen by germinal-center B cells to follicular T cells engenders the process of antibody affinity maturation and humoral memory. Pierce and colleagues show that TLR9 signaling in B cells antagonizes B cell–mediated antigen presentation, which leads to the enhanced generation of short-lived plasma cells and the production of lower-affinity antibodies.

Description: Seizures are a common manifestation of hypoxic-ischaemic brain injury in the neonate. In status epilepticus models alterations to GABA A R subunit expression have been suggested to contribute to 1) abnormal development of the GABAergic system, 2) why seizures become self-sustaining and 3) the development of pharmacoresistance. Detailed investigation of GABA A R subunit protein expression after neonatal hypoxia-ischaemia (HI) is currently insufficient. Using our pig model of HI and subsequent spontaneous neonatal seizures, we investigated changes in protein expression of the three predominant α-subunits of the GABA A R; α 1 , α 2 and α 3 . Anaesthetised, ventilated newborn pigs (〈24h old) were subjected to 30 min HI and subsequently recovered to 24 or 72h. Amplitude-integrated electroencephalography was used to monitor brain activity and identify seizure activity. Brain tissue was collected post mortem and GABA A R α-subunit protein expression was analysed using western blot and immunohistochemistry. GABA A R α 1 and α 3 protein expression was significantly reduced in animals that developed seizures after HI; HI animals that did not develop seizures did not exhibit the same reductions. Immunohistochemistry revealed decreased α 1 and α 3 expression, and α 1 redistribution from the cell membrane to the cytosol, in the hippocampus of seizure animals. Multivariate analyses, controlling for HI severity and neuronal injury, revealed that seizures were independently associated with significant GABA A R α 3 reduction. This is the first study to show loss and redistribution of GABA A R α-subunits in a neonatal brain experiencing seizures. Our findings are similar to those reported in models of SE and in chronic epilepsy. This article is protected by copyright. All rights reserved.

Description: The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand, and the growing recognition that baseflow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day baseflow across large regions. We adapted and applied the spatially referenced regression on watershed attributes (SPARROW) water quality model to assess the spatial distribution of baseflow, the fraction of streamflow supported by baseflow, and estimates of and potential processes contributing to the amount of baseflow that is lost during in-stream transport in the Upper Colorado River Basin (UCRB). On average, 56% of the streamflow in the UCRB originated as baseflow, and precipitation was identified as the dominant driver of spatial variability in baseflow at the scale of the UCRB, with the majority of baseflow discharge to streams occurring in upper elevation watersheds. The model estimates an average of 1.8x10 10 m 3 /yr of baseflow in the UCRB; greater than 80% of which is lost during in-stream transport to the Lower Colorado River Basin via processes including evapotranspiration and water diversion for irrigation. Our results indicate that surface waters in the Colorado River Basin are dependent on baseflow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin. This article is protected by copyright. All rights reserved.