A chemogenomic screen in Saccharomyces cerevisiae uncovers a primary role for the mitochondria in farnesol toxicity and its regulation by the Pkc1 pathway

The isoprenoid farnesol has been shown to preferentially induce apoptosis in cancerous cells; however, the mode of action of farnesol-induced death is not established. We used chemogenomic profiling using Saccharomyces cerevisiae to probe the core cellular processes targeted by farnesol. This screen revealed 48 genes whose inactivation increased sensitivity to farnesol. The gene set indicated a role for the generation of oxygen radicals by the Rieske iron-sulfur component of complex III of the electron transport chain as a major mediator of farnesol-induced cell death. Consistent with this, loss of mitochondrial DNA, which abolishes electron transport, resulted in robust resistance to farnesol. A genomic interaction map predicted interconnectedness between the Pkc1 signaling pathway and farnesol sensitivity via regulation of the generation of reactive oxygen species. Consistent with this prediction (i) Pkc1, Bck1, and Mkk1 relocalized to the mitochondria upon farnesol addition, (ii) inactivation of the only non-essential and non-redundant member of the Pkc1 signaling pathway, BCK1, resulted in farnesol sensitivity, and (iii) expression of activated alleles of PKC1, BCK1, and MKK1 increased resistance to farnesol and hydrogen peroxide. Sensitivity to farnesol was not affected by the presence of the osmostabilizer sorbitol nor did farnesol affect phosphorylation of the ultimate Pkc1-responsive kinase responsible for controlling the cell wall integrity pathway, Slt2. The data indicate that the generation of reactive oxygen species by the electron transport chain is a primary mechanism by which farnesol kills cells. The Pkc1 signaling pathway regulates farnesol-mediated cell death through management of the generation of reactive oxygen species.     

Nitrogen isotope values of Pennisetum glaucum (pearl millet) grains: towards a reconstruction of past cultivation conditions in the Sahel,West Africa

Vegetation History and Archaeobotany - The nitrogen isotope compositions of charred wheat and barley grains reflect manuring intensity and have been used to reconstruct past manuring practices at...     

Design and synthesis of a novel series of cyanoindole derivatives as potent γ-secretase modulators

The discovery, design and synthesis of a new series of GSMs is described. The classical imidazole heterocycle has been replaced by a cyano group attached to an indole nucleus. The exploration of this series has led to compound 26-S which combined high in vitro and in vivo potency with an acceptable drug-like profile.     

A late phase of Oskar accumulation is crucial for posterior patterning of the Drosophila embryo, and is blocked by ectopic expression of Bruno

In Drosophila, posterior embryonic body patterning and germ cell formation rely on Oskar, a protein that is concentrated at the posterior pole of the oocyte. A program of mRNA localization and translational regulation ensures that Oskar is only expressed at the proper location. One key regulatory factor is Bruno, which represses translation of oskar mRNA before its localization. Ectopic expression of a bruno cDNA prolongs repression, even after oskar mRNA is localized, and posterior body patterning is efficiently and selectively blocked. Surprisingly, the initial accumulation of Oskar, while frequently reduced, is not eliminated, arguing that levels of Oskar previously thought to be sufficient for patterning do not suffice, or that Bruno acts at a downstream step in patterning. Expression of the bruno cDNA does not inhibit posterior patterning when Oskar is expressed independent of Bruno-mediated regulation, ruling out a downstream requirement for Bruno. Notably, an Oskar::GFP reporter protein reveals continual accumulation during the late phases of oogenesis. Taken together, these results strongly argue that a late phase in accumulation of Osk protein, typically not monitored because of imperviousness of late stage oocytes to antibodies, is crucial for body patterning.     

Who Bites the Bullet First? The Susceptibility of Leopards Panthera pardus to Trophy Hunting

Reliable data is fundamentally important for managing large carnivore populations, and vital for informing hunting quota levels if those populations are subject to trophy hunting. Camera-trapping and spoor counts can provide reliable population estimates for many carnivores, but governments typically lack the resources to implement such surveys over the spatial scales required to inform robust quota setting. It may therefore be prudent to shift focus away from estimating population size and instead focus on monitoring population trend. In this paper we assess the susceptibility of African leopards Panthera pardus to trophy hunting. This has management ramifications, particularly if the use of harvest composition is to be explored as a metric of population trend. We explore the susceptibility of different leopard age and sex cohorts to trophy hunting; first by examining their intrinsic susceptibility to encountering trophy hunters using camera-traps as surrogates, and second by assessing their extrinsic susceptibility using photographic questionnaire surveys to determine their attractiveness to hunters. We show that adult male and female leopards share similar incident rates to encountering hunters but adult males are the most susceptible to hunting due to hunter preference for large trophies. In contrast, sub-adult leopards rarely encounter hunters and are the least attractive trophies. We suggest that our findings be used as a foundation for the exploration of a harvest composition scheme in the Kwazulu-Natal and Limpopo provinces where post mortem information is collected from hunted leopards and submitted to the local provincial authorities.     

Analysis on Population Level Reveals Trappability of Wild Rodents Is Determined by Previous Trap Occupant

Live trapping is central to the study of small mammals. Thus, any bias needs to be understood and accounted for in subsequent analyses to ensure accurate population estimates. One rarely considered bias is the behavioural response of individuals to the trap, in particular the olfactory cues left behind by previous occupants (PO). We used a data set of 8,115 trap nights spanning 17 separate trapping sessions between August 2002 and November 2013 in Wytham Woods, Oxfordshire, UK to examine if the decision to enter a trap was affected by the PO, if this was detectable in traditional Capture-Mark-Recapture trapping data (i.e., individuals not uniquely marked), and if it was possible for this effect to bias the population estimates obtained. Data were collected on Apodemus sylvaticus, Myodes glareolus, and Microtus agrestis. Three Generalised Linear Models revealed a significant tendency for the three species to enter traps with same-species PO. With, for example, A. sylvaticus 9.1 times more likely to enter a same species PO trap compared to one that contained a M. agrestis in the grassland during the nocturnal period. Simulation highlighted that, when all other factors are equal, the species with the highest PO effect will have the highest capture rate and therefore return more accurate population estimates. Despite the large dataset, certain species-, sex-, and/ or age-combinations were under-represented, and thus no effects of any additional individual-specific characteristics could be evaluated. Uniquely marking individuals would allow for the PO effect to be disentangled from other biases such as trap-shyness and spatial heterogeneity, but may not be possible in all cases and will depend on the aims of the study and the resources available.     

Identifying Loci Contributing to Natural Variation in Xenobiotic Resistance in Drosophila

Natural populations exhibit a great deal of interindividual genetic variation in the response to toxins, exemplified by the variable clinical efficacy of pharmaceutical drugs in humans, and the evolution of pesticide resistant insects. Such variation can result from several phenomena, including variable metabolic detoxification of the xenobiotic, and differential sensitivity of the molecular target of the toxin. Our goal is to genetically dissect variation in the response to xenobiotics, and characterize naturally-segregating polymorphisms that modulate toxicity. Here, we use the Drosophila Synthetic Population Resource (DSPR), a multiparent advanced intercross panel of recombinant inbred lines, to identify QTL (Quantitative Trait Loci) underlying xenobiotic resistance, and employ caffeine as a model toxic compound. Phenotyping over 1,700 genotypes led to the identification of ten QTL, each explaining 4.5–14.4% of the broad-sense heritability for caffeine resistance. Four QTL harbor members of the cytochrome P450 family of detoxification enzymes, which represent strong a priori candidate genes. The case is especially strong for Cyp12d1, with multiple lines of evidence indicating the gene causally impacts caffeine resistance. Cyp12d1 is implicated by QTL mapped in both panels of DSPR RILs, is significantly upregulated in the presence of caffeine, and RNAi knockdown robustly decreases caffeine tolerance. Furthermore, copy number variation at Cyp12d1 is strongly associated with phenotype in the DSPR, with a trend in the same direction observed in the DGRP (Drosophila Genetic Reference Panel). No additional plausible causative polymorphisms were observed in a full genomewide association study in the DGRP, or in analyses restricted to QTL regions mapped in the DSPR. Just as in human populations, replicating modest-effect, naturally-segregating causative variants in an association study framework in flies will likely require very large sample sizes.     

Non-steroidal glucocorticoid agonists: the discovery of aryl pyrazoles as A-ring mimetics

Starting from an established series of non-steroidal glucocorticoid receptor (GR) agonists, a large array was designed where a metabolically labile benzoxazinone moiety was replaced. Initial hits bound to GR but lacked agonist activity. Following two further iterations, potent GR agonists were discovered with 20D1E1 having NFkappaB agonism pIC(50) 8.8 (103%). Other analogues such as 23D1E1 display a dissociated profile (NFkappaB pIC(50) 8.1 (103%), MMTV pEC(50) 7.02 (36%)). The tetrahydronaphthalene moiety can also be replaced with substituted aryls such as 24E1 and 25E1.     

Synthesis and biological evaluation of phosphonate derivatives as autotaxin (ATX) inhibitors

Autotaxin (ATX) is an autocrine motility factor that promotes cancer cell invasion, cell migration, and angiogenesis. ATX, originally discovered as a nucleotide phosphodiesterase, is known now to be responsible for the lysophospholipid-preferring phospholipase D activity in plasma. As such, it catalyzes the production of lysophosphatidic acid (LPA) from lysophophatidylcholine (LPC). ATX is thus an attractive drug target; small molecular inhibitors might be efficacious in slowing the spread of cancers. With this study we have generated a series of beta-keto and beta-hydroxy phosphonate derivatives of LPA, some of which are potent ATX inhibitors.