A combination of the herbicide paraquat (PQ) and fungicide maneb (MB) has been linked to Parkinson's disease. Previous studies show that this involves an additive toxicity with at least two different mechanisms. However, detailed understanding of mixtures is often difficult to elucidate because of the multiple ways by which toxic agents can interact. In the present study, we used a combination of transcriptomics and metabolomics to investigate mechanisms of toxicity of PQ and MB in a neuroblastoma cell line. Conditions were studied with concentrations of PQ and MB that each individually caused 20% cell death and together caused 50% cell death. Transcriptomic and metabolomic samples were collected at time points prior to significant cell death. Statistical and bioinformatic methods were applied to the resulting 30,869 transcripts and 1358 metabolites. Results showed that MB significantly changed more transcripts and metabolites than PQ, and combined PQ. +. MB impacted more than MB alone. Transcriptome-metabolome-wide association study (TMWAS) showed that significantly changed transcripts and metabolites mapped to two network substructures, one associating with significant effects of MB and the other included features significantly associated with PQ. +. MB. The latter contained 4 clusters of genes and associated metabolites, with one containing genes for two cation transporters and a cation transporter regulatory protein also recognized as a pro-apoptotic protein. Other clusters included stress response genes and transporters linked to cytoprotective mechanisms. MB also had a significant network structure linked to cell proliferation. Together, the results show that the toxicologic mechanism of the combined neurotoxicity of PQ and MB involves network level interactions and that TMWAS provides an effective approach to investigate such complex mechanisms.
Plants and fungi often produce toxic secondary metabolites that limit their consumption, but herbivores and fungivores that evolve resistance gain access to these resources and can also gain protection against non-resistant predators and parasites. Given that larvae of the fruitfly Drosophila melanogaster consume yeasts growing on rotting fruit and have evolved resistance to yeast fermentation products such as ethanol, we decided to test whether ethanol protects fruitflies from one of their most common natural parasites, endoparasitoid wasps. Here, we show that exposure to ethanol reduces wasp oviposition into fruitfly larvae. Furthermore, if infected, ethanol consumption by fruitfly larvae causes increased death of wasp larvae growing in the hemocoel and increased fly survival without need of the stereotypical anti-wasp immune response. This multi-faceted protection afforded to fly larvae by ethanol is significantly more effective against a generalist wasp than a wasp that specializes on D. melanogaster. Finally, fly larvae seek out ethanol-containing food when infected, indicating they use alcohol as an anti-wasp medicine. Although the high resistance of D. melanogaster may make it uniquely suited to exploit curative properties of alcohol, it is possible that alcohol consumption may have similar protective effects in other organisms.
In the embryonic neural tube, multiple signaling pathways work in concert to create functional neuronal circuits in the adult spinal cord. In the ventral neural tube, Sonic hedgehog (Shh) acts as a graded morphogen to specify neurons necessary for movement. In the dorsal neural tube, bone morphogenetic protein (BMP) and Wnt signals cooperate to specify neurons involved in sensation. Several signaling pathways, including Shh, rely on primary cilia in vertebrates. In this study, we used a mouse mutant with abnormal cilia, Arl13bhnn, to study the relationship between cilia, cell signaling, and neural tube patterning. Alr13bhnn mutants have abnormal ventral neural tube patterning due to disrupted Shh signaling; in addition, dorsal patterning defects occur, but the cause of these is unknown. Here we show that the Arl13bhnn dorsal patterning defects result from abnormal BMP signaling. In addition, we find that Wnt ligands are abnormally expressed in Arl13bhnn mutants; surprisingly, however, downstream Wnt signaling is normal. We demonstrate that Arl13b is required non-autonomously for BMP signaling and Wnt ligand expression, indicating that the abnormal Shh signaling environment in Arl13bhnn embryos indirectly causes dorsal defects.
The nonlinearity of dynamics in systems biology makes it hard to infer them from experimental data. Simple linear models are computationally efficient, but cannot incorporate these important nonlinearities. An adaptive method based on the S-system formalism, which is a sensible representation of nonlinear mass-action kinetics typically found in cellular dynamics, maintains the efficiency of linear regression. We combine this approach with adaptive model selection to obtain efficient and parsimonious representations of cellular dynamics. The approach is tested by inferring the dynamics of yeast glycolysis from simulated data. With little computing time, it produces dynamical models with high predictive power and with structural complexity adapted to the difficulty of the inference problem.
Drosophila melanogaster has long been used as a model for the molecular genetics of innate immunity. Such work has uncovered several immune receptors that recognize bacterial and fungal pathogens by binding unique components of their cell walls and membranes. Drosophila also act as hosts to metazoan pathogens such as parasitic wasps, which can infect a majority of individuals in natural populations, but many aspects of their immune responses against these more closely related pathogens are poorly understood. Here, we present data describing the transcriptional induction and molecular evolution of a candidate Drosophila anti-wasp immunity gene, lectin-24A. Lectin-24A has a secretion signal sequence and its lectin domain suggests a function in sugar group binding. Transcript levels of lectin-24A were induced significantly stronger and faster following wasp attack than following wounding or bacterial infection, demonstrating lectin-24A is not a general stress response or defense response gene but is instead part of a specific response against wasps. The major site of lectin-24A transcript production is the fat body, the main humoral immune tissue of flies. Interestingly, lectin-24A is a new gene of the D. melanogaster/Drosophila simulans clade, displaying very little homology to any other Drosophila lectins. Population genetic analyses of lectin-24A DNA sequence data from African and North American populations of D. melanogaster and D. simulans revealed gene length polymorphisms segregating at high frequencies as well as strong evidence of repeated and recent selective sweeps. Thus, lectin-24A is a rapidly evolving new gene that has seemingly developed functional importance for fly resistance against infection by parasitic wasps.
Natural selection has played an important role in establishing various phenotypes, but the molecular mechanisms of phenotypic adaptation are not well understood. The slow progress is a consequence of mutagenesis experiments in which present-day molecules were used and of the limited scope of statistical methods used to detect adaptive evolution. To fully appreciate phenotypic adaptation, the precise roles of adaptive mutations during phenotypic evolution must be elucidated through the engineering and manipulation of ancestral phenotypes. Experimental and quantum chemical analyses of dim-light vision reveal some surprising results and provide a foundation for a productive study of the adaptive evolution of various phenotypes.
Summary
Among humans, face recognition involves highly specialized cognitive and neural processes that enable the recognition of specific individuals [1–5]. While comparative studies suggest similar cognitive processes underlie face recognition in chimpanzees and humans [6–8, SOM#1], it remains unknown whether chimpanzees also show face-selective activity in ventral temporal cortex. This study is the first to examine regional cerebral glucose metabolism using 18F-Flurodeoxyglucose Positron Emission Tomography in chimpanzees after they performed computerized tasks matching conspecifics’ faces and nonface objects (SOM#2). A whole brain analysis comparing these two tasks directly in five chimpanzees revealed significant face-selective activity in brain regions known to comprise the distributed cortical face processing network in humans, including superior temporal sulcus and orbitofrontal cortex [9–11]. In order to identify regions that were exclusively active during one task, but not the other, a resting-state condition was subtracted from each task and the activity exclusive to each task was identified. This revealed numerous distinct patches of face-selective activity in the fusiform gyrus that were interspersed within a large expanse of object-selective cortex. This pattern suggests similar object form topography in the ventral temporal cortex of chimpanzees and humans, in which faces may represent a special class of visual stimulus.
OBJECTIVE
Eliminating health disparities is a national priority, but progress has been difficult because of racial/ethnic differences in insurance coverage and access to health care. We investigated whether there were differences in diabetes care in the Veterans Administration (VA), where health care access should be relatively uniform.
RESEARCH DESIGN AND METHODS
A1C and plasma glucose were compared before/after diagnosis of diabetes.
RESULTS
Data were available for 1,456 black and 2,624 white veterans who met criteria for consistent primary care. Over 4–5 years before and after diagnosis, blacks had similar glucose and ∼0.2% higher A1C levels than whites, and A1C differences could be attributed to glucose-independent associations between race and A1C. Blacks and whites also had comparable intervals between diagnostic-level hyperglycemia and diagnosis and between diagnosis and drug initiation. However, A1C was higher in blacks at the time of diagnosis (7.8 vs. 7.1%) and at initiation of pharmacotherapy (8.5 vs. 7.8%) (both P < 0.001). Differences in A1C at diagnosis and drug initiation were too large to be explained by differences in age, sex, BMI, and glucose-independent associations between race and A1C.
CONCLUSIONS
In the VA, glucose levels are generally comparable in blacks and whites except at the times of diagnosis and initiation of pharmacotherapy, when glucose levels are higher in blacks. While understanding the basis for such residual disparities may be important to improve the health of racial/ethnic minorities in the U.S., a health care system with structure and organization similar to that in the VA may also contribute importantly to relieving disparities in health.
Purpose
Hypoxia inducible factor-1 (HIF-1) is the central mediator of the cellular response to low oxygen and functions as a transcription factor for a broad range of genes that provide adaptive responses to oxygen deprivation. HIF-1 is over-expressed in cancer and has become an important therapeutic target in solid tumors. In this study, a novel HIF-1α inhibitor was identified and its molecular mechanism was investigated.
Experimental Design
Using a HIF-responsive reporter cell-based assay, a 10,000-membered natural product-like chemical compound library was screened to identify novel HIF-1 inhibitors. This led us to discover KC7F2, a lead compound with a central structure of cystamine. The effects of KC7F2 on HIF-1 transcription, translation and protein degradation processes were analyzed.
Results
KC7F2 markedly inhibited HIF-mediated transcription in cells derived from different tumor types, including glioma, breast and prostate cancers and exhibited enhanced cytotoxicity under hypoxia. KC7F2 prevented the activation of HIF-target genes such as Carbonic Anhydrase IX, Matrix Metalloproteinase 2 (MMP2), Endothelin 1 and Enolase 1. Investigation of the mechanism of action of KC7F2 showed that it worked through the down-regulation of HIF-1α protein synthesis, an effect accompanied by the suppression of the phosphorylation of eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) and p70 S6 kinase (S6K), key regulators of HIF-1α protein synthesis.
Conclusion
These results show that KC7F2 is a potent HIF-1 pathway inhibitor and that its potential as a cancer therapy agent warrants further study.
In contrast to planktonic cells, bacteria imbedded biofilms are notoriously refractory to treatment by antibiotics or bacteriophage (phage) used alone. Given that the mechanisms of killing differ profoundly between drugs and phages, an obvious question is whether killing is improved by combining antibiotic and phage therapy. However, this question has only recently begun to be explored. Here, in vitro biofilm populations of Pseudomonas aeruginosa PA14 were treated singly and with combinations of two phages and bactericidal antibiotics of five classes. By themselves, phages and drugs commonly had only modest effects in killing the bacteria. However some phage-drug combinations reduced bacterial densities to well below that of the best single treatment; in some cases, bacterial densities were reduced even below the level expected if both agents killed independently of each other (synergy). Furthermore, there was a profound order effect in some cases: treatment with phages before drugs achieved maximum killing. Combined treatment was particularly effective in killing in Pseudomonas biofilms grown on layers of cultured epithelial cells. Phages were also capable of limiting the extent to which minority populations of bacteria resistant to the treating antibiotic ascend. The potential of combined antibiotic and phage treatment of biofilm infections is discussed as a realistic way to evaluate and establish the use of bacteriophage for the treatment of humans.