The Iron-Dependent Regulator Fur Controls Pheromone Signaling Systems and Luminescence in the Squid Symbiont Vibrio fischeri ES114

Bacteria often use pheromones to coordinate group behaviors in specific environments. While high cell density is required for pheromones to achieve stimulatory levels, environmental cues can also influence pheromone accumulation and signaling. For the squid symbiont Vibrio fischeri ES114, bioluminescence requires pheromone-mediated regulation, and this signaling is induced in the host to a greater extent than in culture, even at an equivalent cell density. Our goal is to better understand this environment-specific control over pheromone signaling and bioluminescence. Previous work with V. fischeri MJ1 showed that iron limitation induces luminescence, and we recently found that ES114 encounters a low-iron environment in its host. Here we show that ES114 induces luminescence at lower cell density and achieves brighter luminescence in low-iron media. This iron-dependent effect on luminescence required ferric uptake regulator (Fur), which we propose influences two pheromone signaling master regulators, LitR and LuxR. Genetic and bioinformatic analyses suggested that under low-iron conditions, Fur-mediated repression of litR is relieved, enabling more LitR to perform its established role as an activator of luxR. Interestingly, Fur may similarly control the LitR homolog SmcR of Vibrio vulnificus. These results reveal an intriguing regulatory link between low-iron conditions, which are often encountered in host tissues, and pheromone-dependent master regulators.     

Functional network organization of the human brain

Real-world complex systems may be mathematically modeled as graphs, revealing properties of the system. Here we study graphs of functional brain organization in healthy adults using resting state functional connectivity MRI. We propose two novel brain-wide graphs, one of 264 putative functional areas, the other a modification of voxelwise networks that eliminates potentially artificial short-distance relationships. These graphs contain many subgraphs in good agreement with known functional brain systems. Other subgraphs lack established functional identities; we suggest possible functional characteristics for these subgraphs. Further, graph measures of the areal network indicate that the default mode subgraph shares network properties with sensory and motor subgraphs: it is internally integrated but isolated from other subgraphs, much like a "processing" system. The modified voxelwise graph also reveals spatial motifs in the patterning of systems across the cortex.     

POLG mutation in a patient with cataracts, early-onset distal muscle weakness and atrophy, ovarian dysgenesis and 3-methylglutaconic aciduria

Mutations in POLG account for one of the most frequent nuclear encoded causes of mitochondrial disorders to date. Individuals harboring POLG mutations exhibit fairly heterogeneous clinical presentations leading to increasing difficulties in classifying these patients into defined clinical phenotypes. This study aims to investigate the molecular basis of a mitochondrial cytopathy in a patient with 3-methylglutaconic aciduria and to expand the clinical phenotype associated with POLG mutations. Clinical, molecular and genetic analyses as well as neurophysiological examinations were carried out for a 23-year-old woman of mixed Caucasian and Latin American ancestry with a history of cataracts diagnosed at age 1 year, she had onset of distal muscle weakness at age 2 years progressing to atrophy and ovarian dysgenesis at puberty. The patient was found to have 3-methylglutaconic acid with normal 3 hydroxyisovaleric acid on urine organic acid analysis. POLG sequencing was done and a heterozygous variant, c.2851T>A (p.Y951N) was found which is predicted to be deleterious. There are limited reports of POLG mutations in individuals with 3-methylglutaconic aciduria. This case report of a young woman with a heterozygous mutation in POLG, presenting with muscle weakness and atrophy at a young age aims to aid clinicians in similar challenging diagnostic situations as well as enhances our understanding of POLG-related disease phenotypes.     

Saturated long-chain fatty acids activate inflammatory signaling in astrocytes

This study describes the effects of long-chain fatty acids on inflammatory signaling in cultured astrocytes. Data show that the saturated fatty acid palmitic acid, as well as lauric acid and stearic acid, trigger the release of TNFα and IL-6 from astrocytes. Unsaturated fatty acids were unable to induce cytokine release from cultured astrocytes. Furthermore, the effects of palmitic acid on cytokine release require Toll-like receptor 4 rather than CD36 or Toll-like receptor 2, and do not depend on palmitic acid metabolism to palmitoyl-CoA. Inhibitor studies revealed that pharmacologic inhibition of p38 or p42/44 MAPK pathways prevents the pro-inflammatory effects of palmitic acid, whereas JNK and PI3K inhibition does not affect cytokine release. Depletion of microglia from primary astrocyte cultures using the lysosomotropic agent l-leucine methyl ester revealed that the ability of palmitic acid to trigger cytokine release is not dependent on the presence of microglia. Finally, data show that the essential ω-3 fatty acid docosahexaenoic acid acts in a dose-dependent manner to prevent the actions of palmitic acid on inflammatory signaling in astrocytes. Collectively, these data demonstrate the ability of saturated fatty acids to induce astrocyte inflammation in vitro. These data thus raise the possibility that high levels of circulating saturated fatty acids could cause reactive gliosis and brain inflammation in vivo, and could potentially participate in the reported adverse neurologic consequences of obesity and metabolic syndrome.     

Development of haplotype-specific molecular markers for the low-molecular-weight glutenin subunits

Low-molecular-weight glutenin subunits (LMW-GSs) are one of the major components of gluten, and their allelic variation has been widely associated with different wheat end-use quality parameters. These proteins are encoded by multigene families located at the orthologous Glu-3 loci (Glu-A3, Glu-B3, and Glu-D3); the genes at each locus are divided by large intergenic and highly recombinogenic regions. Among the methods used for the LMW-GS allele identification, polymerase chain reaction (PCR)-based molecular markers have the advantages of being simple, accurate, and independent from the plant stage of development. However, the available LMW-GS molecular markers are either incapable of capturing the complexity of the LMW-GS gene family or difficult to interpret. In the present study, we report the development of a set of PCR-based molecular markers specific for the LMW-GS haplotypes present at each Glu-3 locus. Based on the LMW-GS gene sequences available in GenBank, single nucleotide polymorphisms (SNPs) specific for each Glu-3 haplotype were identified and the relevant PCR primers were designed. In total, we developed three molecular markers for the Glu-A3 and Glu-B3 loci, respectively, and five molecular markers for the Glu-D3 locus. The markers were tested on 44 bread wheat varieties previously characterized for their LMW-GS genic profile and found to be equally or more efficient than previously developed LMW-GS PCR-based markers. This set of markers allows an easier and less ambiguous identification of specific LMW-GS haplotypes associated with gluten strength and can facilitate marker-assisted breeding for wheat quality.     

Phenyl ureas of creatinine as mGluR5 antagonists. A structure-activity relationship study of fenobam analogues

Fenobam (1) was developed by McNeil Laboratories as an anxiolytic agent with an unknown molecular target in the late 1970s. In a recent publication, it was revealed that fenobam is a non-competitive mGluR5 antagonist. Herein, we present the structure-activity relationship of fenobam and its analogues and similarities between the SAR of mGluR5 antagonism and the SAR of CNS properties originally reported by McNeil are discussed.     

Structure-activity relationship of thiopyrimidines as mGluR5 antagonists

Structure-activity relationship investigations of the thiopyrimidine (1), an HTS hit with micromolar activity as a metabotropic glutamate receptor 5 (mGluR5) antagonist, led to compounds with sub-micromolar activity.