Zoonotic Potential of Simian Arteriviruses

Wild nonhuman primates are immediate sources and long-term reservoirs of human pathogens. However, ethical and technical challenges have hampered the identification of novel blood-borne pathogens in these animals. We recently examined RNA viruses in plasma from wild African monkeys and discovered several novel, highly divergent viruses belonging to the family Arteriviridae. Close relatives of these viruses, including simian hemorrhagic fever virus, have caused sporadic outbreaks of viral hemorrhagic fever in captive macaque monkeys since the 1960s. However, arterivirus infection in wild nonhuman primates had not been described prior to 2011. The arteriviruses recently identified in wild monkeys have high sequence and host species diversity, maintain high viremia, and are prevalent in affected populations. Taken together, these features suggest that the simian arteriviruses may be “preemergent” zoonotic pathogens. If not, this would imply that biological characteristics of RNA viruses thought to facilitate zoonotic transmission may not, by themselves, be sufficient for such transmission to occur.     

Association of Ant Predators and Edaphic Conditions with Termite Diversity in an Amazonian Rain Forest

Predation is a key determinant of prey community structure, but few studies have measured the effect of multiple predators on a highly diverse prey community. In this study, we asked whether the abundance, species richness, and species composition of a species‐rich assemblage of termites in an Amazonian rain forest is more strongly associated with the density of predatory ants or with measures of vegetation, and soil texture and chemistry. We sampled termite assemblages with standardized hand‐collecting in 30 transects arranged in a 5 km × 6 km grid in a terra firme Amazonian rain forest. For each transect, we also measured vegetation structure, soil texture, and soil phosphorus, and estimated the density of predatory ants from baits, pitfall traps, and Winkler samples. Seventy‐nine termite species were recorded, and the total density of predatory ants was the strongest single predictor of local termite abundance (r = ?0.66) and termite species richness (r = ?0.44). In contrast, termite abundance and species richness were not strongly correlated with edaphic conditions (¦r¦ < 0.01), or with the density of non‐predatory ants (r_abund = ?0.27; r_s = ?0.06). Termite species composition was correlated with soil phosphorus content (r = 0.79), clay content (r = ?0.75), and tree density (r = ?0.42). Assemblage patterns were consistent with the hypothesis that ants collectively behaved as generalist predators, reducing total termite abundance, and species richness. There was no evidence that ants behaved as keystone predators, or that any single termite species benefited from the reduction in the abundance of potential competitors.     

Drought Impacts Survivorship and Reproductive Strategies of an Epiphyllous Leafy Liverwort in Central Amazonia

Understanding how changing precipitation patterns impact the population dynamics of Amazonian plants is necessary for predicting their long‐term survival. Most terrestrial plants are characterized by life cycles intractably slow for evaluating such demographic consequences. Due to the demands of surviving on an ephemeral substrate such as a leaf surface, epiphyllous (leaf‐inhabiting) bryophytes have some of the fastest generation times for terrestrial plants. Considering these advantages, we investigated the demographic consequences of seasonality in precipitation during one‐year of the epiphyllous bryophyte Radula flaccida Gott. (Radulaceae) in a central Amazonian rain forest. In a 1‐ha sized study area, 154 epiphyll colonies from 18 phorophytes of the understory shrub Naucleopsis ulei (Warb.) Ducke (Moraceae) were marked and colony growth, extinction, recolonization, as well as rates of sexual and asexual expression were measured in nine demographic censuses. The probability of survivorship decreased in the dry season due to the synergistic effects of both increased leaf fall (e.g., loss of occupied patches) and colony mortality on persisting leaves. Asexual expression also declined significantly during the driest months; however, sexual expression, as measured by sporophyte density, was not related to seasonality. Logistic regression probabilities also indicate a minimum threshold colony size for optimal sporophyte expression. Lower survivorship and colony growth in the dry season along with reduced sporophyte production in smaller colonies implies that both demographic stability as well as population structure of Amazonian epiphyll species may be compromised whether climate models projecting prolonged droughts for the region are accurate.     

Kinetic modeling of phototrophic biofilms: the PHOBIA model

A kinetic model for mixed phototrophic biofilms is introduced, which focuses on the interactions between photoautotrophic, heterotrophic, and chemoautotrophic (nitrifying) functional microbial groups. Biofilm-specific phenomena are taken into account, such as extracellular polymeric substances (EPS) production by phototrophs as well as gradients of substrates and light in the biofilm. Acid-base equilibria, in particular carbon speciation, are explicitly accounted for, allowing for the determination of pH profiles across the biofilm. Further to previous models reported in literature, the PHOBIA model combines a number of kinetic mechanisms specific to phototrophic microbial communities, such as internal polyglucose storage under dynamic light conditions, phototrophic growth in the darkness using internally stored reserves, photoadaptation and photoinhibition, preference for ammonia over nitrate as N-source and the ability to utilize bicarbonate as a carbon source in the absence of CO(2). The sensitivity of the PHOBIA model to a number of key parameters is analyzed. An example on the potential use of phototrophic biofilms in wastewater polishing is discussed, where their performance is compared with conventional algal ponds. The PHOBIA model is presented in a manner that is compatible with other reference models in the area of water treatment. Its current version forms a theoretical base which is readily extendable once further experimental observations become available.     

Electrical and mechanical effects induced by cold temperatures in the ventricle of isolated Rana ridibunda hearts

A temperature decrease changes the contractility of the amphibian heart, but the underlying mechanisms are not totally understood. The objectives of the present work were to better understand the intrinsic mechanisms supporting contractility changes induced by a rapid temperature decrease in the ventricle of Rana ridibunda, and to investigate how fast they develop. Ventricular mechanical cycles (VMCs) and monophasic action potentials (MAPs) recorded from 15 isolated hearts were measured at 15, 30, 45, 60, 90, 120 and 150 s after the application of Ringer solutions of 20, 10 and 5 degrees C. Treatment with 10 and 5 degrees C Ringer solutions decreased the heart rate, and increased the magnitude of the ventricular contraction and the duration of the contraction and relaxation periods. The electrical changes included prolongation of the MAP depolarization plateau, which also decreased in amplitude as an effect of perfusion with 5 degrees C Ringer solution. In addition, treatment with 5 degrees C Ringer solution increased the latency of contraction. The block of L-type channels totally abolished the depolarization plateau at all perfusion temperatures, but failed to inhibit ventricular contraction. In conclusion, treatment with cold temperatures changes the electrical activity of the ventricular myocardium in R. ridibunda hearts, which results in modified ventricular contractility. Data suggest that in addition to L-type Ca2+ channels, other components that support calcium elevation are present R. ridibunda ventricular cells.     

Potential anti-inflammatory actions of the elmiric (lipoamino) acids

A library of amino acid-fatty acid conjugates (elmiric acids) was synthesized and evaluated for activity as potential anti-inflammatory agents. The compounds were tested in vitro for their effects on cell proliferation and prostaglandin production, and compared with their effects on in vivo models of inflammation. LPS stimulated RAW 267.4 mouse macrophage cells were the in vitro model and phorbol ester-induced mouse ear edema served as the principal in vivo model. The prostaglandin responses were found to be strongly dependent on the nature of the fatty acid part of the molecule. Polyunsaturated acid conjugates produced a marked increase in media levels of i15-deoxy-PGJ(2) with minimal effects on PGE production. It is reported in the literature that prostaglandin ratios in which the J series predominates over the E series promote the resolution of inflammatory conditions. Several of the elmiric acids tested here produced such favorable ratios suggesting that their potential anti-inflammatory activity occurs via a novel mechanism of action. The ear edema assay results were generally in agreement with the prostaglandin assay findings indicating a connection between them.