Non-Universality in Semi-Directed Barabasi-Albert Networks

In usual scale-free networks of Barabasi-Albert type, a newly added node selects randomly m neighbors from the already existing network nodes, proportionally to the number of links these had before. Then the number N(k) of nodes with k links each decays as 1/k^gamma where gamma=3 is universal, i.e. independent of m. Now we use a limited directedness in the construction of the network, as a result of which the exponent gamma decreases from 3 to 2 for increasing m.Comment: 5 pages including 2 figures and computer progra

Immunogenetic novelty confers a selective advantage in host–pathogen coevolution

The major histocompatibility complex (MHC) is crucial to the adaptive immune response of vertebrates and is among the most polymorphic gene families known. Its high diversity is usually attributed to selection imposed by fast-evolving pathogens. Pathogens are thought to evolve to escape recognition by common immune alleles, and, hence, novel MHC alleles, introduced through mutation, recombination, or gene flow, are predicted to give hosts superior resistance. Although this theoretical prediction underpins host–pathogen “Red Queen” coevolution, it has not been demonstrated in the context of natural MHC diversity. Here, we experimentally tested whether novel MHC variants (both alleles and functional “supertypes”) increased resistance of guppies (Poecilia reticulata) to a common ectoparasite (Gyrodactylus turnbulli). We used exposure-controlled infection trials with wild-sourced parasites, and Gyrodactylus-naïve host fish that were F2 descendants of crossed wild populations. Hosts carrying MHC variants (alleles or supertypes) that were new to a given parasite population experienced a 35–37% reduction in infection intensity, but the number of MHC variants carried by an individual, analogous to heterozygosity in single-locus systems, was not a significant predictor. Our results provide direct evidence of novel MHC variant advantage, confirming a fundamental mechanism underpinning the exceptional polymorphism of this gene family and highlighting the role of immunogenetic novelty in host–pathogen coevolution

New trends in cannabis potency in USA and Europe during the last decade (2008-2017)

Through the potency monitoring program at the University of Mississippi supported by National Institute on Drug Abuse (NIDA), a total of 18108 samples of cannabis preparations have been analyzed over the last decade, using a validated GC/FID method. The samples are classified as sinsemilla, marijuana, ditchweed, hashish, and hash oil (now referred to as cannabis concentrate). The number of samples received over the last 5 years has decreased dramatically due to the legalization of marijuana either for medical or for recreational purposes in many US states. The results showed that the mean Δ9-THC concentration has increased dramatically over the last 10 years, from 8.9% in 2008 to 17.1% in 2017. The mean Δ9-THC:CBD ratio also rose substantially from 23 in 2008 to 104 in 2017. There was also marked increase in the proportion of hash oil samples (concentrates) seized (0.5-4.7%) and their mean Δ9-THC concentration (6.7-55.7%) from 2008 to 2017. Other potency monitoring programs are also present in several European countries such as The Netherlands, United Kingdom, France, and Italy. These programs have also documented increases in Δ9-THC concentrations and Δ9-THC:CBD ratios in cannabis. These trends in the last decade suggest that cannabis is becoming an increasingly harmful product in the USA and Europe.</p

Aqueous Solution Equilibria and Spectral Features of Copper Complexes with Tripeptides Containing Glycine or Sarcosine and Leucine or Phenylalanine

Copper(II) complexes of glycyl-L-leucyl-L-histidine (GLH), sarcosyl-L-leucyl-L-histidine (Sar-LH), glycyl-L-phenylalanyl-L-histidine (GFH) and sarcosyl-L-phenylalanyl-L-histidine (Sar-FH) have potential anti-inflammatory activity, which can help to alleviate the symptoms associated with rheumatoid arthritis (RA). From pH 2&ndash;11, the MLH, ML, MLH-1 and MLH-2 species formed. The combination of species for each ligand was different, except at the physiological pH, where CuLH-2 predominated for all ligands. The prevalence of this species was supported by EPR, ultraviolet-visible spectrophotometry, and mass spectrometry, which suggested a square planar CuN4 coordination. All ligands have the same basicity for the amine and imidazole-N, but the methyl group of sarcosine decreased the stability of MLH and MLH-2 by 0.1&ndash;0.34 and 0.46&ndash;0.48 log units, respectively. Phenylalanine increased the stability of MLH and MLH-2 by 0.05&ndash;0.29 and 1.19&ndash;1.21 log units, respectively. For all ligands, 1H NMR identified two coordination modes for MLH, where copper(II) coordinates via the amine-N and neighboring carbonyl-O, as well as via the imidazole-N and carboxyl-O. EPR spectroscopy identified the MLH, ML and MLH-2 species for Cu-Sar-LH and suggested a CuN2O2 chromophore for ML. DFT calculations with water as a solvent confirmed the proposed coordination modes of each species at the B3LYP level combined with 6-31++G**

Validating a predictive model of cannabinoid inheritance with feral, clinical, and industrial Cannabis sativa

© 2020 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America Premise: How genetic variation within a species affects phytochemical composition is a fundamental question in botany. The ratio of two specialized metabolites in Cannabis sativa, tetrahydrocannabinol (THC) and cannabidiol (CBD), can be grouped into three main classes (THC-type, CBD-type, and intermediate type). We tested a genetic model associating these three groups with functional and nonfunctional alleles of the cannabidiolic acid synthase gene (CBDAS). Methods: We characterized cannabinoid content and assayed CBDAS genotypes of \u3e300 feral C. sativa plants in Minnesota, United States. We performed a test cross to assess CBDAS inheritance. Twenty clinical cultivars obtained blindly from the National Institute on Drug Abuse and 12 Canadian-certified grain cultivars were also examined. Results: Frequencies of CBD-type, intermediate-type, and THC-type feral plants were 0.88, 0.11, and 0.01, respectively. Although total cannabinoid content varied substantially, the three groupings were perfectly correlated with CBDAS genotypes. Genotype frequencies observed in the test cross were consistent with codominant Mendelian inheritance of the THC:CBD ratio. Despite significant mean differences in total cannabinoid content, CBDAS genotypes blindly predicted the THC:CBD ratio among clinical cultivars, and the same was true for industrial grain cultivars when plants exhibited \u3e0.5% total cannabinoid content. Conclusions: Our results extend the generality of the inheritance model for THC:CBD to diverse C. sativa accessions and demonstrate that CBDAS genotyping can predict the ratio in a variety of practical applications. Cannabinoid profiles and associated CBDAS segregation patterns suggest that feral C. sativa populations are potentially valuable experimental systems and sources of germplasm

The FGF-21 genetic variants rs838133 and rs838145 are associated with high salt intake in the Emirati population

Food predilection is linked to variants in the hepatokine “Fibroblast Growth Factor-21” gene (FGF21); with rs838133 linked to the sweet tooth in Caucasians. The effect of FGF21 variants on food intake is still unclear in other populations. A cohort of 196 healthy Emirati subjects was investigated [age: 30.34 ± 9.75yrs (44.4% males)]. The FGF21 rs838133 and rs838145 were genotyped. The daily intake was calculated based on a 61-item food frequency questionnaire. Multivariate analysis was performed using in house R script that implements two-way unsupervised hierarchical clustering to detect the association of the studied single-nucleotide polymorphisms (SNPs) and related SNPs in linkage disequilibrium, using data from the 1000 genome project. Both SNPs were in Hardy-Weinberg Equilaribium (HWE). BMI positively correlated with age (p = 0.002), but not with caloric intake. Salt intake was significantly higher in subjects homozygous (A: rs838133) and (G:rs838145),(p = 0.03 and 0.01, respectively). An interaction was observed between both SNPs; significantly associated with high salt intake. Using publicly available data, both SNPs fall within a region transmitted in Iberians which has a profile closely similar to Caucasians, but far from Chinese population. In conclusion, the minor alleles of FGF21 rs838145 and rs838133 are associated with high salt intake in Emiratis and may suggest neuro-metabolic link to dietary preference across different populations

Metformin reduces airway glucose permeability and hyperglycaemia-induced Staphylococcus aureus load independently of effects on blood glucose

Background Diabetes is a risk factor for respiratory infection, and hyperglycaemia is associated with increased glucose in airway surface liquid and risk of Staphylococcus aureus infection. Objectives To investigate whether elevation of basolateral/blood glucose concentration promotes airway Staphylococcus aureus growth and whether pretreatment with the antidiabetic drug metformin affects this relationship. Methods Human airway epithelial cells grown at air–liquid interface (±18 h pre-treatment, 30 μM–1 mM metformin) were inoculated with 5×105 colony-forming units (CFU)/cm2 S aureus 8325-4 or JE2 or Pseudomonas aeruginosa PA01 on the apical surface and incubated for 7 h. Wild-type C57BL/6 or db/db (leptin receptor-deficient) mice, 6–10 weeks old, were treated with intraperitoneal phosphate-buffered saline or 40 mg/kg metformin for 2 days before intranasal inoculation with 1×107 CFU S aureus. Mice were culled 24 h after infection and bronchoalveolar lavage fluid collected. Results Apical S aureus growth increased with basolateral glucose concentration in an in vitro airway epithelia–bacteria co-culture model. S aureus reduced transepithelial electrical resistance (RT) and increased paracellular glucose flux. Metformin inhibited the glucose-induced growth of S aureus, increased RT and decreased glucose flux. Diabetic (db/db) mice infected with S aureus exhibited a higher bacterial load in their airways than control mice after 2 days and metformin treatment reversed this effect. Metformin did not decrease blood glucose but reduced paracellular flux across ex vivo murine tracheas. Conclusions Hyperglycaemia promotes respiratory S aureus infection, and metformin modifies glucose flux across the airway epithelium to limit hyperglycaemia-induced bacterial growth. Metformin might, therefore, be of additional benefit in the prevention and treatment of respiratory infection

Probabilistic Reuse of Past Search Results

International audienceIn this paper, a new Monte Carlo algorithm to improve precision of information retrieval by using past search results is presented. Experiments were carried out to compare the proposed algorithm with traditional retrieval on a simulated dataset. In this dataset, documents, queries, and judgments of users were simulated. Exponential and Zipf distributions were used to build document collections. Uniform distribution was applied to build the queries. Zeta distribution was utilized to simulate the Bradford’s law representing the judgments of users. Empirical results show a better performance of our algorithm compared with traditional retrieval