Genes Associated with 2-Methylisoborneol Biosynthesis in Cyanobacteria: Isolation, Characterization, and Expression in Response to Light

The volatile microbial metabolite 2-methylisoborneol (2-MIB) is a root cause of taste and odor issues in freshwater. Although current evidence suggests that 2-MIB is not toxic, this compound degrades water quality and presents problems for water treatment. To address these issues, cyanobacteria and actinomycetes, the major producers of 2-MIB, have been investigated extensively. In this study, two 2-MIB producing strains, coded as Pseudanabaena sp. and Planktothricoids raciborskii, were used in order to elucidate the genetic background, light regulation, and biochemical mechanisms of 2-MIB biosynthesis in cyanobacteria. Genome walking and PCR methods revealed that two adjacent genes, SAM-dependent methyltransferanse gene and monoterpene cyclase gene, are responsible for GPP methylation and subsequent cyclization to 2-MIB in cyanobacteria. These two genes are located in between two homologous cyclic nucleotide-binding protein genes that may be members of the Crp-Fnr regulator family. Together, this sequence of genes forms a putative operon. The synthesis of 2-MIB is similar in cyanobacteria and actinomycetes. Comparison of the gene arrangement and functional sites between cyanobacteria and other organisms revealed that gene recombination and gene transfer probably occurred during the evolution of 2-MIB-associated genes. All the microorganisms examined have a common origin of 2-MIB biosynthesis capacity, but cyanobacteria represent a unique evolutionary lineage. Gene expression analysis suggested that light is a crucial, but not the only, active regulatory factor for the transcription of 2-MIB synthesis genes. This light-regulated process is immediate and transient. This study is the first to identify the genetic background and evolution of 2-MIB biosynthesis in cyanobacteria, thus enhancing current knowledge on 2-MIB contamination of freshwater

Histologic assessment of biliary obstruction with different percutaneous endoluminal techniques

BACKGROUND: Despite the sophisticated cross sectional image techniques currently available, a number of biliary stenosis or obstructions remain of an uncertain nature. In these pathological conditions, an "intrinsic" parietal alteration is the cause of biliary obstruction and it is very difficult to differentiate benign from malignant lesions using cross-sectional imaging procedures alone. We evaluated the efficacy of different endoluminal techniques to achieve a definitive pathological diagnosis in these situations. METHODS: Eighty patients underwent brushing, and or biopsy of the biliary tree through an existing transhepatic biliary drainage route. A subcoort of 12 patients needed balloon-dilatation of the bile duct and the material covering the balloon surface was also sent for pathological examination (balloon surface sampling). Pathological results were compared with surgical findings or with long-term clinical and instrumental follow-ups. Success rates, sensitivity, specificity, accuracy, confidential intervals, positive predictive value and negative predictive value of the three percutaneous techniques in differentiating benign from malignant disease were assessed. The agreement coefficient of biopsy and brushing with final diagnosis was calculated using the Cohen's "K" value. RESULTS: Fifty-six patients had malignant strictures confirmed by surgery, histology, and by clinical follow-ups. Success rates of brushing, balloon surface sampling, and biopsy were 90.7, 100, and 100%, respectively. The comparative efficacy of brushing, balloon-surface sampling, and biopsy resulted as follows: sensitivity of 47.8, 87.5, and 92.1%, respectively; specificity of 100% for all the techniques; accuracy of 69.2, 91.7 and 93.6%, Positive Predictive Value of 100% for all the procedures and Negative Predictive Value of 55, 80, and 75%, respectively. CONCLUSIONS: Percutaneous endoluminal biopsy is more accurate and sensitive than percutaneous bile duct brushing in the detection of malignant diseases (p < 0.01)

STRP Screening Sets for the human genome at 5 cM density

BACKGROUND: Short tandem repeat polymorphisms (STRPs) are powerful tools for gene mapping and other applications. A STRP genome scan of 10 cM is usually adequate for mapping single gene disorders. However mapping studies involving genetically complex disorders and especially association (linkage disequilibrium) often require higher STRP density. RESULTS: We report the development of two separate 10 cM human STRP Screening Sets (Sets 12 and 52) which span all chromosomes. When combined, the two Sets contain a total of 782 STRPs, with average STRP spacing of 4.8 cM, average heterozygosity of 0.72, and total sex-average coverage of 3535 cM. The current Sets are comprised almost entirely of STRPs based on tri- and tetranucleotide repeats. We also report correction of primer sequences for many STRPs used in previous Screening Sets. Detailed information for the new Screening Sets is available from our web site: . CONCLUSION: Our new human STRP Screening Sets will improve the quality and cost effectiveness of genotyping for gene mapping and other applications

Fresh-blood-free diet for rearing malaria mosquito vectors

Mosquito breeding depends on the supply of fresh vertebrate blood, a major bottleneck for large-scale production of Anopheles spp. Feeding alternatives to fresh blood are thus a priority for research, outdoor large-cage trials and control interventions. Several artificial meal compositions were tested and Anopheles oogenesis, egg laying and development into the next generation of adult mosquitoes were followed. We identified blood-substitute-diets that supported ovarian development, egg maturation and fertility as well as, low progeny larval mortality, and normal development of offspring into adult mosquitoes. The formulated diet is an effective artificial meal, free of fresh blood that mimics a vertebrate blood meal and represents an important advance for the sustainability of Anopheles mosquito rearing in captivity.Agência financiadora / Número do subsídio Bill and Melinda Gates Foundation OPP1138841 Fundacao para a Ciencia e Tecnologia GHTM - UID/Multi/04413/201 CCMAR - UID/Multi/04326/2013 UID/Multi/04326/2013 RF SFRH/BPD/89811/2012 FAPEAM, Brazil 19716.UNI472.2459.20022014info:eu-repo/semantics/publishedVersio

Effective Rheology of Bubbles Moving in a Capillary Tube

We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

Global Pyrogeography: the Current and Future Distribution of Wildfire

Climate change is expected to alter the geographic distribution of wildfire, a complex abiotic process that responds to a variety of spatial and environmental gradients. How future climate change may alter global wildfire activity, however, is still largely unknown. As a first step to quantifying potential change in global wildfire, we present a multivariate quantification of environmental drivers for the observed, current distribution of vegetation fires using statistical models of the relationship between fire activity and resources to burn, climate conditions, human influence, and lightning flash rates at a coarse spatiotemporal resolution (100 km, over one decade). We then demonstrate how these statistical models can be used to project future changes in global fire patterns, highlighting regional hotspots of change in fire probabilities under future climate conditions as simulated by a global climate model. Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free. In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables. Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe. These changes could have important effects on terrestrial ecosystems since alteration in fire activity may occur quite rapidly, generating ever more complex environmental challenges for species dispersing and adjusting to new climate conditions. Our findings highlight the potential for widespread impacts of climate change on wildfire, suggesting severely altered fire regimes and the need for more explicit inclusion of fire in research on global vegetation-climate change dynamics and conservation planning

Disrupting Circadian Homeostasis of Sympathetic Signaling Promotes Tumor Development in Mice

and why disruption of circadian rhythm may lead to tumorigenesis. oncogenic potential, leading to tumor development in the same organ systems in wild-type and circadian gene-mutant mice. is a clock-controlled physiological function. The central circadian clock paces extracellular mitogenic signals that drive peripheral clock-controlled expression of key cell cycle and tumor suppressor genes to generate a circadian rhythm in cell proliferation. Frequent disruption of circadian rhythm is an important tumor promoting factor