26 research outputs found
New insights into the infection process of Rhynchosporium secalis in barley using GFP
No full textThrough the use of a Rhynchosporium secalis isolate transformed with the green fluorescent protein gene and LASER scanning confocal microscopy (LSCM), fungal development during the R. secalis/barley interaction was analysed. Each infection stage was investigated from 0.5h to 14 days post-inoculation (p.i.) with extensive sampling within the first 48 h p.i. Early germination events were observed that had not been previously described. A specific time of germination was noted, with germ tube formation appearing as early as 1h p.i. Conidia were observed within anticlinal grooves of epidermal cells and the formation of bubbles within these pectin-rich regions was observed within 24h p.i. The study reports R. secalis pectinase production and suggests degradation of these pectin-rich regions. Reactive oxygen species were present during early penetration, 3h p.i. and co-localised with fungal development. LSCM allowed the visualisation of fungal growth deep within tissues at the later stage of the infection.Katherine J. Linsell, Felicity J. Keiper, Angus Forgan and Klaus H. Oldachhttp://www.elsevier.com/wps/find/journaldescription.cws_home/622835/description#descriptio
Comparative genome analysis of a Saccharomyces cerevisiae wine strain
No full textArticle first published online: 5 SEP 2008Many industrial strains of Saccharomyces cerevisiae have been selected primarily for their ability to convert sugars into ethanol efficiently despite exposure to a variety of stresses. To begin investigation of the genetic basis of phenotypic variation in industrial strains of S. cerevisiae, we have sequenced the genome of a wine yeast, AWRI1631, and have compared this sequence with both the laboratory strain S288c and the human pathogenic isolate YJM789. AWRI1631 was found to be substantially different from S288c and YJM789, especially at the level of single-nucleotide polymorphisms, which were present, on average, every 150 bp between all three strains. In addition, there were major differences in the arrangement and number of Ty elements between the strains, as well as several regions of DNA that were specific to AWRI1631 and that were predicted to encode proteins that are unique to this industrial strain.Anthony R. Borneman, Angus H. Forgan, Isak S. Pretorius and Paul J. Chamber
Use of a wine yeast deletion collection reveals genes that influence fermentation performance under low-nitrogen conditions
No full text A deficiency of nitrogenous nutrients in grape juice can cause stuck and sluggish alcoholic fermentation, which has long been a problem in winemaking. Nitrogen requirements vary between wine yeast strains, and the ability of yeast to assimilate nitrogen depends on the nature and concentration of nitrogen present in the medium. In this study, a wine yeast gene deletion collection (1844 deletants in the haploid AWRI1631 background) was screened to identify genes whose deletion resulted in a reduction in the time taken to utilise all sugars when grown in a chemically defined grape juice medium supplemented with limited nitrogen (75 mg L -1 as a free amino acid mixture). Through micro-scale and laboratory-scale fermentations, 15 deletants were identified that completed fermentation in a shorter time than the wildtype (c.a. 15%-59% time reduction). This group of genes was annotated to biological processes including protein modification, transport, metabolism and ubiquitination (UBC13, MMS2, UBP7, UBI4, BRO1, TPK2, EAR1, MRP17, MFA2 and MVB12), signalling (MFA2) and amino acid metabolism (AAT2). Deletion of MFA2, encoding mating factor-a, resulted in a 55% decrease in fermentation duration. Mfa2Δ was chosen for further investigation to understand how this gene deletion conferred fermentation efficiency in limited nitrogen conditions. </p
The genome sequence of the wine yeast VIN7 reveals an allotriploid hybrid genome with Saccharomyces cerevisiae and Saccharomyces kudriavzevii origins
No full textThe vast majority of wine fermentations are performed principally by Saccharomyces cerevisiae. However, there are a growing number of instances in which other species of Saccharomyces play a predominant role. Interestingly, the presence of these other yeast species generally occurs via the formation of interspecific hybrids that contain genomic contributions from both S. cerevisiae and non-S. cerevisiae species. However, despite the large number of wine strains that are characterized at the genomic level, there remains limited information regarding the detailed genomic structure of hybrids used in winemaking. To address this, we describe the genome sequence of the thiol-releasing commercial wine yeast hybrid VIN7. VIN7 is shown to be an almost complete allotriploid interspecific hybrid that is comprised of a heterozygous diploid complement of S. cerevisiae chromosomes and a haploid Saccharomyces kudriavzevii genomic contribution. Both parental strains appear to be of European origin, with the S. cerevisiae parent being closely related to, but distinct from, the commercial wine yeasts QA23 and EC1118. In addition, several instances of chromosomal rearrangement between S. cerevisiae and S. kudriavzevii sequences were observed that may mark the early stages of hybrid genome consolidation.Anthony R. Borneman, Brian A. Desany, David Riches, Jason P. Affourtit, Angus H. Forgan, Isak S. Pretorius, Michael Egholm & Paul J. Chamber
Whole genome comparison reveals high levels of inbreeding and strain redundancy across the spectrum of commercial wine strains of Saccharomyces cerevisiae
No full textPublished Early Online February 11, 2016.Humans have been consuming wines for more than 7000 yr . For most of this time, fermentations were presumably performed by strains of Saccharomyces cerevisiae that naturally found their way into the fermenting must . In contrast, most commercial wines are now produced by inoculation with pure yeast monocultures, ensuring consistent, reliable and reproducible fermentations, and there are now hundreds of these yeast starter cultures commercially available. In order to thoroughly investigate the genetic diversity that has been captured by over 50 yr of commercial wine yeast development and domestication, whole genome sequencing has been performed on 212 strains of S. cerevisiae, including 119 commercial wine and brewing starter strains, and wine isolates from across seven decades. Comparative genomic analysis indicates that, despite their large numbers, commercial strains, and wine strains in general, are extremely similar genetically, possessing all of the hallmarks of a population bottle-neck, and high levels of inbreeding. In addition, many commercial strains from multiple suppliers are nearly genetically identical, suggesting that the limits of effective genetic variation within this genetically narrow group may be approaching saturation.Anthony R. Borneman, Angus H. Forgan, Radka Kolouchova, James A. Fraser, and Simon A. Schmid
Commentary on "Graphite and its hidden superconductivity"
No full textA Commentary on the paper by P. Esquinazi [Pap. Phys. 5, 050007 (2013)]. The author of the paper offers a Reply.Received: 10 October 2013,, Accepted: 4 November 2013; Edited by: S. A. Grigera; DOI: http://dx.doi.org/10.4279/PIP.05000
On the feasibility of exomoon detection via exoplanet phase curve spectral contrast
No full textThe author gratefully acknowledges support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ERC-2011-ADG.An exoplanet-exomoon system presents a superposition of phase curves to observers - the dominant component varies according to the planetary period, and the lesser component varies according to both the planetary and the lunar periods. If the spectra of the two bodies differ significantly, then it is likely that there are wavelength regimes where the contrast between the moon and planet is significantly larger. In principle, this effect could be used to isolate periodic oscillations in the combined phase curve. Being able to detect the exomoon component would allow a characterization of the exomoon radius, and potentially some crude atmospheric data. We run a parameter survey of combined exoplanet-exomoon phase curves, which shows that for most sets of planet-moon parameters, the lunar component of the phase curve is undetectable to current state-of-the-art transit observations. Even with future transit survey missions, measuring the exomoon signal will most likely require photometric precision of 10 parts per million or better. The only exception to this is if the moon is strongly tidally heated or in some way self-luminous. In this case, measurements of the phase curve at wavelengths greater than a few μm can be dominated by the lunar contribution. Instruments like the James Webb Space Telescope and its successors are needed to make this method feasible.Peer reviewe
Exoplanet transits as the foundation of an interstellar communications network
No full textThe author gratefully acknowledges support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ERC-2011-ADG, and the STFC grant ST/J001422/1.Two fundamental problems for extraterrestrial intelligences (ETIs) attempting to establish interstellar communication are timing and energy consumption. Humanity's study of exoplanets via their transit across the host star highlights a means of solving both problems. An ETI ‘A’ can communicate with ETI ‘B’ if B is observing transiting planets in A's star system, either by building structures to produce artificial transits observable by B, or by emitting signals at B during transit, at significantly lower energy consumption than typical electromagnetic transmission schemes. This can produce a network of interconnected civilizations, establishing contact via observing each other's transits. Assuming that civilizations reside in a Galactic Habitable Zone (GHZ), I conduct Monte Carlo Realization simulations of the establishment and growth of this network, and analyse its properties in the context of graph theory. I find that at any instant, only a few civilizations are correctly aligned to communicate via transits. However, we should expect the true network to be cumulative, where a ‘handshake’ connection at any time guarantees connection in the future via e.g. electromagnetic signals. In all our simulations, the cumulative network connects all civilizations together in a complete network. If civilizations share knowledge of their network connections, the network can be fully complete on timescales of order a hundred thousand years. Once established, this network can connect any two civilizations either directly, or via intermediate civilizations, with a path much less than the dimensions of the GHZ.Peer reviewe
Oral history interview with Pauline Hodges
No full textPauline Hodges was born in Liberal, Kansas, in 1929, one month before the stock market crashed and two years before the Dust Bowl. Since her father was a wheat farmer, both of these events had a great impact on her family. She started school at Floris in a one room schoolhouse, then moved to Turpin. When she was nine, her family moved to Forgan, where she graduated in 1947. She is co-author of the book A History of Beaver County
