Fine‐scale variation within urban landscapes affects marking patterns and gastrointestinal parasite diversity in red foxes

1. Urban areas are often considered to be a hostile environment for wildlife as they are highly fragmented and frequently disturbed. However, these same habitats can contain abundant resources, while lacking many common competitors and predators. The urban environment can have a direct impact on the species living there but can also have indirect effects on their parasites and pathogens. To date, relatively few studies have measured how fine‐scale spatial heterogeneity within urban landscapes can affect parasite transmission and persistence.
2. Here, we surveyed 237 greenspaces across the urban environment of Edinburgh (UK) to investigate how fine‐scale variation in socio‐economic and ecological variables can affect red fox (Vulpes vulpes) marking behavior, gastrointestinal (GI) parasite prevalence, and parasite community diversity.
3. We found that the presence and abundance of red fox fecal markings were nonuniformly distributed across greenspaces and instead were dependent on the ecological characteristics of a site. Specifically, common foraging areas were left largely unmarked, which indicates that suitable resting and denning sites may be limiting factor in urban environments. In addition, the amount of greenspace around each site was positively correlated with overall GI parasite prevalence, species richness, and diversity, highlighting the importance of greenspace (a commonly used measure of landscape connectivity) in determining the composition of the parasite community in urban areas.
4. Our results suggest that fine‐scale variation within urban environments can be important for understanding the ecology of infectious diseases in urban wildlife and could have wider implication for the management of urban carnivores.

     

Interactions between two catalytically distinct MCM subgroups are essential for coordinated ATP hydrolysis and DNA replication.

The six MCM (minichromosome maintenance) proteins are essential DNA replication factors that each contain a putative ATP binding motif and together form a heterohexameric complex. We show that these motifs are required for viability in vivo and coordinated ATP hydrolysis in vitro. Mutational analysis discriminates between two functionally distinct MCM protein subgroups: Mcm4p, 6p, and 7p contribute canonical ATP binding motifs essential for catalysis, whereas the related motifs in Mcm2p, 3p, and 5p serve a regulatory function. Reconstitution experiments indicate that specific functional interactions between these two subgroups are required for robust ATP hydrolysis. Our observations show parallels between the MCM complex and the F1-ATPase, and we discuss how ATP hydrolysis by the MCM complex might be coupled to DNA strand separation.     

Interaction of soil moisture and elevated CO2 on the above-ground growth rate, root length density and gas exchange of turves from temperate pasture

Interactions between water availability and elevated atmosphericCO₂ concentrations have the potential to be important factorsin determining future forage supply from temperate pastures.Using large turves from an established pasture, the responseof these communities at 350 or 700 l l^–1 CO₂ to a soilmoisture deficit and to recovery from the deficit in comparisonto turves that were well-watered throughout was measured. Priorto this experiment the turves had been exposed to the CO₂ treatmentsfor 324 d. Net CO₂ exchange continued at elevated CO₂ even when the volumetricsoil moisture content was less than 0.10 m³ m^–3 soil;at the same moisture deficit gas exchange at ambient CO₂ waszero. The additional carbon fixed by the elevated CO₂ turveswas primarily allocated below-ground as shown by the maintenanceof root length density at the same level as in well-wateredturves. When the dry turves were rewatered there was compensatorygrowth at ambient CO₂ so that the above-ground growth rate exceededthat of turves that had not experienced a moisture deficit.At the start of this experiment, the turves that were growingat 700 l I^–1 CO₂ had a greater proportion of legume (principallywhite clover, Trifolium repens L.) in the harvested herbage.There was a trend for the legume content at elevated CO₂ tobe reduced under a soil moisture deficit. The results indicate different strategies in response to soilmoisture deficits depending on the CO₂ concentration. At ambientCO₂, growth stopped, but plants were able to respond stronglyon rewatering; while at elevated CO₂ growth continued (particularlybelow-ground), but no additional growth was evident on rewatering.Ecosystem gas exchange measurements taken at the end of theexperiment (after 429 d of exposure to CO₂) showed 33% moreCO₂ was fixed at elevated CO₂ with only a small (12%) and nonsignificantdownward regulation. Key words: Carbon dioxide, climate change, grassland, gas exchange, soil moisture deficit     

Isomeric lipid signatures reveal compartmentalized fatty acid metabolism in cancer

The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics.     

Cadmium-substituted skeletal troponin C metal binding investigations and sequence assignment of the cadmium-113 resonances

The binding of cadmium to the calcium binding subunit of skeletal troponin (STnC) has been reinvestigated using direct binding methods and fluorescent derivatives. These data provide straightforward explanations of the observed titration behavior in the 113Cd NMR (Ellis, P.D., Strang, P., and Potter, J.D. (1984) J. Biol. Chem. 259, 10348-10356). Further, fluorescent derivatives of skeletal troponin C provide an excellent means of establishing a sequence assignment for the resonances observed in the 113Cd NMR. The results of these experiments demonstrate that sites I and II, the Ca2+ regulatory sites, can be assigned to resonances at -108.5 and -101.5 ppm, respectively. Sites III and IV, the structural sites, are assigned to resonances -112.8 and -106.8 ppm, respectively. These data are discussed in terms of recent structural findings and speculations.