Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae

Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.Jennifer R. Bellon, Frank Schmid, Dimitra L. Capone, Barbara L. Dunn, Paul J. Chamber

Yeast : the soul of beer’s aroma—a review of flavour-active esters and higher alcohols produced by the brewing yeast

Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.Eduardo Pires gratefully acknowledges the Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) for the PhD fellowship support (SFRH/BD/61777/2009). The financial contributions of the EU FP7 project Ecoefficient Biodegradable Composite Advanced Packaging (EcoBioCAP, grant agreement no. 265669) as well as of the Grant Agency of the Czech Republic (project GACR P503/12/1424) are also gratefully acknowledged. The authors thank the Ministry of Education, Youth and Sports of the Czech Republic (MSM 6046137305) for their financial support

Erythrocytes lacking the Langereis blood group protein ABCB6 are resistant to the malaria parasite Plasmodium falciparum.

The ATP-binding cassette transporter ABCB6 was recently discovered to encode the Langereis (Lan) blood group antigen. Lan null individuals are asymptomatic, and the function of ABCB6 in mature erythrocytes is not understood. Here, we assessed ABCB6 as a host factor for Plasmodium falciparum malaria parasites during erythrocyte invasion. We show that Lan null erythrocytes are highly resistant to invasion by P. falciparum, in a strain-transcendent manner. Although both Lan null and Jr(a-) erythrocytes harbor excess porphyrin, only Lan null erythrocytes exhibit a P. falciparum invasion defect. Further, the zoonotic parasite P. knowlesi invades Lan null and control cells with similar efficiency, suggesting that ABCB6 may mediate P. falciparum invasion through species-specific molecular interactions. Using tandem mass tag-based proteomics, we find that the only consistent difference in membrane proteins between Lan null and control cells is absence of ABCB6. Our results demonstrate that a newly identified naturally occurring blood group variant is associated with resistance to Plasmodium falciparum

The Australian and New Zealand experience of terrestrial ecological risk assessment and potential methods to address current limitations

Extended abstract.Michael Warne, Rebecca Hamon, Mike KcLaughlin, Kathryn O'Halloran, Helen Davies, Elvin Wong, John Chapman, Rai Kookana, Carine Saiso

Validation of a nested PCR assay for detection of Xanthomonas axonopodis pv. dieffenbachiae in anthurium tissue in a European multicenter collaborative trial : [P2-11]

#Xanthomonas axonopodis# pv. #dieffenbachiae# (Xad) is the etiological agent of anthurium bacterial blight. Xad is a quarantine organism in several countries and particularly in Europe where this pathogen is listed in the A2 list of the European and Mediterranean Plant Protection Organization (EPPO). A collaborative trial involving 15 European laboratories was performed to evaluate a Nested PCR assay (1) (NPCR) for the detection of Xad from anthurium samples. This collaborative study was conducted according to the ISO 16140:2003 standard "Protocol for validation of alternative methods"(3). The ISO 16140 validation protocol comprises two phases: a comparative study of methods and a collaborative trial. The comparative study was carried out in the organizing laboratory (CIRAD/LNPV Reunion Island). Methods such as the EPPO reference method for detection of Xad, the N-PCR assay, immunofluorescence (IF) and double antibody sandwich ELISA (DAS-ELISA) were compared. It was shown noticeably differences in performance between methods. The reference and N-PCR methods were the most efficient techniques, both combining a very3 good inclusivity, exclusivity, a relative accuracy above 95% and a low detection threshold (approximately 10 CFU.mL-1). The collaborative trial consisted in determining the variability of the results obtained by several different competent laboratories using identical samples and in comparing these results to those obtained with the comparative study. Four blinded samples (8 replicates/sample) were analysed by the 15 laboratories. The four samples were constituted of an anthurium extract artificially contaminated with variable concentrations of the pathotype strain (0, 104 or 105 CFU.mL-1), or with a non-target strain (107CFU.mL-1). The N-PCR assay was performed in comparison to a reference method (isolation of the bacteria on non-selective and semi-selective media followed by a serological identification by indirect ELISA) and to other methods, DASELISA and IF, all included in the EPPO standard (2). The relative accuracy, relative specificity, relative sensitivity, accordance and concordance values obtained for the N-PCR assay were 96.0%, 95.0%, 97.5%, 94.0% and 93.0% respectively. The results obtained with the N-PCR assay were significantly different from the theoretically expected results (p<0.05),but it became non-significant when one laboratory (laboratory N) was excluded from the analysis (p=0.15). The results obtained with DAS-ELISA and IF were significantly different from the theorically expected results (p<0.001 and p<0.05 respectively). A significant variation between laboratories was shown for one of the four samples for the N-PCR assay (p<0.05). However, it became not significant when one laboratory (laboratory N) was excluded (p=1.00). Variations between laboratories were significant for one of the four evaluated samples for DAS-ELISA (p<0.001) and for the four evaluated samples for IF (p<0.001 to p<0.05). The analysis of the data suggested that these significant variations for DAS-ELISA and IF were linked to the characteristics of these methods and to the expertise of the laboratories. The N-PCR has been included into the EPPO standard as an alternative method for the detection of #Xanthomonas axonopodis# pv. #dieffenbachiae# in anthurium plants (2). Because of its high specificity, the addition of the N-PCR technique in the EPPO standard now makes the pathogenicity tests to anthurium optional, substantially reducing the amount of time for result delivery. (Résumé d'auteur

Clinically relevant mutations in the ABCG2 transporter uncovered by genetic analysis linked to erythrocyte membrane protein expression

The ABCG2 membrane protein is a key xeno- and endobiotic transporter, modulating the absorption and metabolism of pharmacological agents and causing multidrug resistance in cancer. ABCG2 is also involved in uric acid elimination and its impaired function is causative in gout. Analysis of ABCG2 expression in the erythrocyte membranes of healthy volunteers and gout patients showed an enrichment of lower expression levels in the patients. By genetic screening based on protein expression, we found a relatively frequent, novel ABCG2 mutation (ABCG2-M71V), which, according to cellular expression studies, causes reduced protein expression, although with preserved transporter capability. Molecular dynamics simulations indicated a stumbled dynamics of the mutant protein, while ABCG2-M71V expression in vitro could be corrected by therapeutically relevant small molecules. These results suggest that personalized medicine should consider this newly discovered ABCG2 mutation, and genetic analysis linked to protein expression provides a new tool to uncover clinically important mutations in membrane proteins. © 2018 The Author(s)

Diagnostic Accuracy of a Prototype Point-of-Care Test for Ocular Chlamydia trachomatis under Field Conditions in The Gambia and Senegal

Trachoma, caused by infection of the eye with the bacterium Chlamydia trachomatis, is the leading infectious cause of blindness and is associated with poverty. Antibiotic treatment of all community members is one of the recommended control strategies for trachoma. However, in places where the prevalence of clinical signs is low, C. trachomatis eye infection is often absent. Laboratory testing for C. trachomatis infection by polymerase chain reaction (PCR) is highly sensitive but expensive and requires well-trained staff. A simple point-of-care (POC) test that can be used in trachoma-affected communities could help trachoma control efforts. We evaluated a POC test for C. trachomatis eye infection. Children under 10 years of age were screened for clinical signs of trachoma and C. trachomatis eye infection. The POC test result was compared with laboratory PCR test results. The POC test detected just over half of PCR test positives correctly. However, the POC test tended to give false-positive results in hot and dry conditions, which is the typical environment of trachoma. The POC test requires high specificity since it would be used to make treatment decisions at the community level. Therefore, its present format requires improvement before it can be utilized in trachoma control