Latitudinal differentiation in the effects of the toxic dinoflagellate Alexandrium spp. on the feeding and reproduction of populations of the copepod Acartia hudsonica

Blooms of the dinoflagellate Alexandrium spp. increase in their frequency, toxicity and historical presence with increasing latitude from New Jersey (USA) to the Gaspé peninsula (Canada). Biogeographic variation in these blooms results in differential exposure of geographically separate copepod populations to toxic Alexandrium. We hypothesize that the ability of copepods to feed and reproduce on toxic Alexandrium should be higher in copepods from regions that are frequently exposed to toxic Alexandrium blooms. We tested this hypothesis with factorial common environment experiments in which female adults of the copepod Acartia hudsonica from five separate populations ranging from New Jersey to New Brunswick were fed toxic and non-toxic strains of Alexandrium, and the non-toxic flagellate Tetraselmis sp. Consistent with the hypothesis, when fed toxic Alexandrium we observed significantly higher ingestion and egg production rates in the copepods historically exposed to toxic Alexandrium blooms relative to copepods from regions in which Alexandrium is rare or absent. Such differences among copepod populations were not observed when copepods were fed non-toxic Alexandrium or Tetraselmis sp. These results were also supported by assays in which copepods from populations both historically exposed and naïve to toxic Alexandrium blooms were fed mixtures of toxic Alexandrium and Tetraselmis sp. Two-week long experiments demonstrated that when copepods from populations naïve to toxic Alexandrium were fed a toxic strain of Alexandrium they failed to acclimate, such that their ingestion rates remained low throughout the entire two-week period. The differences observed among populations suggest that local adaptation of populations of A. hudsonica from Massachusetts (USA) to New Brunswick (Canada) has occurred, such that some populations are resistant to toxic Alexandrium.     

Potent, orally active inhibitors of lipoprotein-associated phospholipase A(2): 1-(biphenylmethylamidoalkyl)-pyrimidones.

A series of 1-(biphenylmethylamidoalkyl)-pyrimidones has been designed as nanomolar inhibitors of recombinant lipoprotein-associated phospholipase A(2) with high potency in whole human plasma. 5-(Pyrazolylmethyl) derivative 16 and 5-(methoxypyrimidinylmethyl) derivative 27 demonstrated excellent pharmacodynamic profiles which correlated well with their pharmacokinetic effects.     

Phylogenetic Analysis of Bacterial Communities in Different Regions of the Gastrointestinal Tract of Agkistrodon piscivorus,the Cottonmouth Snake

Vertebrates are metagenomic organisms in that they are composed not only of their own genes but also those of their associated microbial cells. The majority of these associated microorganisms are found in the gastrointestinal tract (GIT) and presumably assist in processes such as energy and nutrient acquisition. Few studies have investigated the associated gut bacterial communities of non-mammalian vertebrates, and most rely on captive animals and/or fecal samples only. Here we investigate the gut bacterial community composition of a squamate reptile, the cottonmouth snake, Agkistrodon piscivorus through pyrosequencing of the bacterial 16S rRNA gene. We characterize the bacterial communities present in the small intestine, large intestine and cloaca. Many bacterial lineages present have been reported by other vertebrate gut community studies, but we also recovered unexpected bacteria that may be unique to squamate gut communities. Bacterial communities were not phylogenetically clustered according to GIT region, but there were statistically significant differences in community composition between regions. Additionally we demonstrate the utility of using cloacal swabs as a method for sampling snake gut bacterial communities.     

Evolutionary Reconstructions of the Transferrin Receptor of Caniforms Supports Canine Parvovirus Being a Re-emerged and Not a Novel Pathogen in Dogs

Parvoviruses exploit transferrin receptor type-1 (TfR) for cellular entry in carnivores, and specific interactions are key to control of host range. We show that several key mutations acquired by TfR during the evolution of Caniforms (dogs and related species) modified the interactions with parvovirus capsids by reducing the level of binding. These data, along with signatures of positive selection in the TFRC gene, are consistent with an evolutionary arms race between the TfR of the Caniform clade and parvoviruses. As well as the modifications of amino acid sequence which modify binding, we found that a glycosylation site mutation in the TfR of dogs which provided resistance to the carnivore parvoviruses which were in circulation prior to about 1975 predates the speciation of coyotes and dogs. Because the closely-related black-backed jackal has a TfR similar to their common ancestor and lacks the glycosylation site, reconstructing this mutation into the jackal TfR shows the potency of that site in blocking binding and infection and explains the resistance of dogs until recent times. This alters our understanding of this well-known example of viral emergence by indicating that canine parvovirus emergence likely resulted from the re-adaptation of a parvovirus to the resistant receptor of a former host.     

Playing it safe? Solitary vervet monkeys (Chlorocebus pygerythrus) choose high‐quality foods more than those in competition

An important goal in foraging ecology is to determine how biotic and abiotic variables impact the foraging decisions of wild animals and how they move throughout their multidimensional landscape. However, the interaction of food quality and feeding competition on foraging decisions is largely unknown. Here we examine the importance of food quality in a patch on the foraging decisions of wild vervet monkeys (Chlorocebus pygerythrus) at Lake Nabugabo, Uganda using a multidestination platform array. The overall nutritional composition of the vervet diet was assessed and found to be low in sodium and lipids, thus we conducted a series of experimental manipulations in which the array was varied in salt and oil content. Although vervets prioritized platforms containing key nutrients (i.e., sodium and lipids) overall, we found that solitary vervets prioritized nutrient‐dense platforms more strongly than competing vervets. This finding was opposite to those in a similar experiment that manipulated food site quantity, suggesting that large, salient rewards may be worth competing over but slight differences in nutritional density may be only chosen when there are no potentially negative social consequences (i.e., aggression received). We also found that vervets chose platforms baited with oil‐only, and oil combined with salt, but not salt‐only, suggesting that energy was an important factor in food choice. Our findings demonstrate that when wild vervets detect differences in feeding patches that reflect nutritional composition, they factor these differences into their navigational and foraging decisions. In addition, our findings suggest that these nutritional differences may be considered alongside social variables, ultimately leading to the complex strategies we observed in this study.