Yeast strains from the endogenous microflora of the olive fliesBactrocera oleae larvae which could degrade the olive oil mill wastewaters polyphenols

Worldwide, wastewaters constitute a major environmental pollutant. They are very toxic against a wide range of plants and soil microorganisms. Their toxicity is due to the presence of compounds such as polyphenols. In this study, we have isolated yeast strains from the endogenous microflora of the olive fliesBactrocera oleae larvae that were capable of degrading the olive oil mill wastewater polyphenols. The results obtained showed the presence, in the digestive tract of the larvae, of yeast strains resisting to polyphenols. Two resistant strains were isolated and have shown variable capacity of polyphenols degradation that could reach up to 72%. The two isolated strains were identified by two methods: conventional technique and molecular method associating PCR amplification and DNA sequencing of the 5.8S ribosomal RNA gene. Both techniques showed that the two isolated strains corresponded to theCandida diddensiae specie. Related to its capacity to degrade polyphenols, this specie would be a potential candidate for wastewater treatment and environmental protection.     

Structural basis of allele variation of human thiopurine-S-methyltransferase

Human thiopurine S-methyltransferase (TPMT) exhibits considerable person-to-person variation in activity to thiopurine drugs. We have produced an N-terminal truncation of human TPMT protein, crystallized the protein in complex with the methyl donor product S-adenosyl-L-homocysteine, and determined the atomic structure to the resolution of 1.58 and 1.89 A, respectively, for the seleno-methionine incorporated and wild type proteins. The structure of TPMT indicates that the naturally occurring amino acid polymorphisms scatter throughout the structure, and that the amino acids whose alteration have the most influence on function are those that form intra-molecular stabilizing interactions (mainly van der Waals contacts). Furthermore, we have produced four TPMT mutant proteins containing variant alleles of TPMT*2, *3A, *3B, and *3C and examined the structure-function relationship of the mutant proteins based on their expression and solubility in bacteria and their thermostability profile.     

Bayesian estimation of dominance merits in noninbred populations by using Gibbs sampling with two reduced sets of mixed model equations

Henderson's mixed model equations system is generally required in a Gibbs sampling application. In two previous studies, we proposed two indirect solving approaches that give dominance values in an animal model context with no need to process all this system. The first one does not require D-1 and the second is based on processing the additive animal model residuals. In the present work, we show that these two methods can be handled iteratively. Since the Bayesian approach is now a widely used tool in estimation of genetic parameters, the main part of this work is devoted to a Gibbs sampling application that can be accelerated by means of the aforementioned indirect solving methods. Three replicates of a population data set are simulated in the paper to compare the applications and estimates. This shows effectively that the estimates given by implementing a Gibbs sampler with each of the two suggested solving methods are obtained with less computational time and are comparable to those given by considering the integral system, particularly when priors are more weighted.     

Etude de la respiration, à l’état isolé, des haplotypes de l’abeille tunisienne Apis mellifera intermissa (Buttel Reepen 1906) (Hymenoptera : Apidae)

L’étude de la respiration de l’abeille domestique, Apis mellifera intermissa, à l’état isolé a été réalisée sur les quatre haplotypes existant en Tunisie : A1, A4, A8 et A9 et sous différentes températures : 0°, 10°, 15°, 20°, 25°, 30° et 35°C. Des mesures effectuées sur 1000 abeilles isolées (250 de chaque haplotype) ont montré que la consommation d’oxygène de l’abeille varie en fonction de la température. L’intensité respiratoire des haplotypes augmente progressivement à partir de 0°C pour atteindre son maximum à 15°C. Au-delà de cette température, la consommation d’oxygène de l’abeille diminue progressivement. Pour les basses températures (0° et 10°C), la respiration de l’abeille dépend aussi du facteur génétique et la consommation d’oxygène est faible mais ne s’annule pas. Cette étude a montré qu’il existe une différence de consommation d’oxygène entre les haplotypes A1 et A8 et les haplotypes A4 et A9 pour les basses températures. Le déclenchement de la thermogenèse chez les haplotypes A1 et A8 se produit à 15°C, alors que chez les haplotypes A4 et A9, il a lieu à une température plus basse et qui est de 10°C.     

Human Brucellosis in Maghreb: Existence of a Lineage Related to Socio-Historical Connections with Europe

Despite control/eradication programs, brucellosis, major worldwide zoonosis due to the Brucella genus, is endemic in Northern Africa and remains a major public health problem in the Maghreb region (Algeria/Morocco/Tunisia). Brucella melitensis biovar 3 is mostly involved in human infections and infects mainly small ruminants. Human and animal brucellosis occurrence in the Maghreb seems still underestimated and its epidemiological situation remains hazy. This study summarizes official data, regarding Brucella melitensis infections in Algeria, from 1989 to 2012, with the purpose to provide appropriate insights concerning the epidemiological situation of human and small ruminant brucellosis in Maghreb. Algeria and Europe are closely linked for historical and economical reasons. These historical connections raise the question of their possible impact on the genetic variability of Brucella strains circulating in the Maghreb. Other purpose of this study was to assess the genetic diversity among Maghreb B. melitensis biovar 3 strains, and to investigate their possible epidemiological relationship with European strains, especially with French strains. A total of 90 B. melitensis biovar 3 Maghreb strains isolated over a 25 year-period (1989–2014), mainly from humans, were analysed by MLVA-16. The obtained results were compared with genotypes of European B. melitensis biovar 3 strains. Molecular assays showed that Algerian strains were mainly distributed into two distinct clusters, one Algerian cluster related to European sub-cluster. These results led to suggest the existence of a lineage resulting from socio-historical connections between Algeria and Europe that might have evolved distinctly from the Maghreb autochthonous group. This study provides insights regarding the epidemiological situation of human brucellosis in the Maghreb and is the first molecular investigation regarding B. melitensis biovar 3 strains circulating in the Maghreb.     

Autoregulation by the juxtamembrane region of the human ephrin receptor tyrosine kinase A3 (EphA3)

Ephrin receptors (Eph) affect cell shape and movement, unlike other receptor tyrosine kinases that directly affect proliferative pathways. The kinase domain of EphA3 is activated by ephrin binding and receptor oligomerization. This activation is associated with two tyrosines in the juxtamembrane region; these tyrosines are sites of autophosphorylation and interact with the active site of the kinase to modulate activity. This allosteric event has important implications both in terms of understanding signal transduction pathways mediated by Eph kinases as well as discovering specific therapeutic ligands for receptor kinases. In order to provide further details of the molecular mechanism through which the unphosphorylated juxtamembrane region blocks catalysis, we studied wild-type and site-specific mutants in detail. High-resolution structures of multiple states of EphA3 kinase with and without the juxtamembrane segment allowed us to map the coupled pathway of residues that connect the juxtamembrane segment, the activation loop, and the catalytic residues of the kinase domain. This highly conserved set of residues likely delineates a molecular recognition pathway for most of the Eph RTKs, helping to characterize the dynamic nature of these physiologically important enzymes.     

Large gallanes and the PSEPT theory: a theoretical study of Ga n H n+2 clusters (n?=?7–9)

Do alanes Al(n)H(n+2) and gallanes Ga(n)H(n+2) satisfy the polyhedral skeletal electron pair theory (PSEPT)? Taking into account previous work on this question, this paper provides a convincing answer and proposes the reformulation of the (n + 1) electron pairs rule of Wade and Mingos (W-M) for such systems. Following recent studies of tetra-, penta-, hexa-, hepta-, octa-, and nonaalanes as well as valence-isoelectronic/related gallanes, in this paper we present an analysis of the hydrides of aluminum and gallium A(n)H(n+2) (A = Al, Ga and n = 7-9). The aim is still to examine the applicability of PSEPT, especially the W-M rule, to these clusters. Exploration of the total potential energy surfaces (PESs) of hepta-, octa-, and nonagallanes shows that the absolute minima have a nido-like polyhedron arrangement. Unlike the smaller Ga(n)H(n+2) (n = 4, 5, 6), it seems that the size of the cluster largely dictates its preferred geometry. Although none of them have closed (totally triangular) cages, these clusters exhibit significant compactness, comparable to borane double anions, B(n)H(n) (2-), which are the archetypes for the PSEPT theory.     

Impact of TP53 codon 72 and MDM2 promoter 309 allelic dosage in a Moroccan population with hepatocellular carcinoma

Single-nucleotide polymorphisms (SNPs) in codon 72 of the TP53 gene (rs1042522) and in the promoter region of the MDM2 gene (SNP309; rs2279744) have been shown to play a role in the predisposition to many cancers. However, these findings were inconsistent in other tumor types, and ethnicity is suspected to be a critical factor influencing the effects of these SNPs on the cancer risk. The aim of the present study was to investigate whether these functional SNPs were associated with an enhanced risk of liver tumorigenesis in Moroccan patients. We have genotyped both polymorphisms in 96 patients with hepatocellular carcinoma (HCC) and 222 controls without HCC matched for age, gender and ethnicity by PCR-RFLP confirmed by sequencing. A joint effect between the MDM2 and TP53 polymorphisms and an increased risk of liver cancer was detected, with the odds ratio for the presence of both MDM2 309GG and TP53 72Pro/Pro genotypes being 10 (95% confidence interval 0.39-255.55). Interestingly, a significant increase in the HCC risk was observed when at least two deleterious alleles were present, indicating an allele dosage effect. There was no evidence for any association with early age of HCC onset when deleterious alleles of MDM2 SNP309 and TP53 Arg72Pro where present. Our findings suggest that the combination of TP53 72Pro and MDM2 309G polymorphisms enhance the risk of developing HCC. These results deserve further confirmation in other populations.     

Structural basis for molecular recognition and presentation of histone H3 by WDR5

Histone methylation at specific lysine residues brings about various downstream events that are mediated by different effector proteins. The WD40 domain of WDR5 represents a new class of histone methyl-lysine recognition domains that is important for recruiting H3K4 methyltransferases to K4-dimethylated histone H3 tail as well as for global and gene-specific K4 trimethylation. Here we report the crystal structures of full-length WDR5, WDR5Delta23 and its complexes with unmodified, mono-, di- and trimethylated histone H3K4 peptides. The structures reveal that WDR5 is able to bind all of these histone H3 peptides, but only H3K4me2 peptide forms extra interactions with WDR5 by use of both water-mediated hydrogen bonding and the altered hydrophilicity of the modified lysine 4. We propose a mechanism for the involvement of WDR5 in binding and presenting histone H3K4 for further methylation as a component of MLL complexes.