1,720,961 research outputs found
Homoplasmy restoration of mitochondrial DNA: a non-stochastic event in heteroplasmic Saccharomyces hybrid zygotes
No full textHomoplasmy restoration of mitochondrial DNA: a non-stochastic event in heteroplasmic Saccharomyces hybrid zygote
Fast method for identifying inter- and intra-species Saccharomyces hybrids in extensive genetic improvement programs based on yeast breeding
Full text linkAims: The present work proposes a two-step molecular strategy to select inter- and intra-species Saccharomyces hybrids obtained by spore-to-spore mating, one of the most used methods for generating improved hybrids from homothallic wine yeasts. Methods and Results: As low spore viability and haplo-selfing are the main causes of failed mating, at first, we used colony screening PCR (csPCR) of discriminative gene markers to select hybrids directly on dissection plate and discard homozygous diploid colonies arisen from one auto-diploidized progenitor. Then, pre-selected candidates were submitted to recursive streaking and conventional PCR in order to discriminate between the hybrids with stable genomic background and the false-positive admixtures of progenitor cells both undergone haplo-selfing. csPCRs of internal transcribed spacer (ITS) 1 or 2, and the subsequent digestion with diagnostic endonucleases HaeIII and RsaI, respectively, were efficient to select six new Saccharomyces cerevisiae × Saccharomyces uvarum hybrids from 64 crosses. Intragenic minisatellite regions in PIR3, HSP150, and DAN4 genes showed high inter-strain size variation detectable by cost-effective agarose gel electrophoresis and were successful to validate six new intra-species S. cerevisiae hybrids from 34 crosses. Conclusions: Both protocols reduce significantly the number of massive DNA extractions, prevent misinterpretations caused by one or both progenitors undergone haplo-selfing, and can be easily implemented in yeast labs without any specific instrumentation. Significance and Impact of the Study: The study provides a method for the marker-assisted selection of several inter- and intra-species yeast hybrids in a cost-effective, rapid and reproducible manner
Screening dell’attività β-glucosidasica in ceppi di Saccharomyces spp. isolati da mosto
No full textNei lieviti, l'attività della β-glucosidasi è stata ampiamente descritta, specialmente nelle specie non-Saccharomyces, mentre questa attività risulta essere poco evidente nei ceppi appartenente al genere Saccharomyces. In enologia l'attività β-glucosidasica è un carattere di interesse, in quanto correlata al miglioramento dell'espressione aromatica dei vini. Infatti, il suddetto enzima va ad agire sulla classe dei composti aromatici terpenici. Tali composti si trovano sotto forma di coniugati β-glucosidici nelle varietà d'uva aromatiche come Moscato e Gewürztraminer. La forma coniugata è tuttavia non volatile e, conseguentemente, non aromatica. La presente ricerca fornisce nuove conoscenze sull'attività della β-glucosidasi in ceppi di interesse enologico appartenenti alle specie Saccharomyces cerevisiae e Saccharomyces uvarum. In particolare, 75 ceppi, isolati da mosto d’uva refrigerato e appartenenti alle due specie suddette, sono stati valutati relativamente all’attività β-glucosidasica, sia dal punto di vista qualitativo che quantitativo. Lo screening qualitativo in piastra, mediante l’uso di substrati cromogenici, quali esculina e arbutina, ha messo in evidenza un maggior grado di positività dei test provati per i ceppi della specie S. uvarum rispetto a quelli della specie S. cerevisiae. Successivamente, sui ceppi positivi ad entrambi i due precedenti test, è stato condotto un test quantitativo dell’attività β-glucosidasica, mediante il metodo spettrofotomentrico basato sull’idrolisi del p‐nitrophenyl‐β‐D‐glucopyranoside (p‐NPG). La valutazione è stata effettuata su tre diverse frazioni dei campioni analizzati: il surnatante, il lisato cellulare e le cellule intere. I risultati ottenuti hanno messo in evidenza che l'attività enzimatica è principalmente associata alle cellule intere. Inoltre, tre ceppi di S. uvarum, CRY14, VA42 and GRAS14, hanno mostrato una pronunciata attività β-glucosidasica (Bonciani et al., 2018). Questi ceppi potrebbero essere sfruttati per la loro potenziale capacità di migliorare i profili aromatici del vino. Più in generale, lo studio apre un nuovo e promettente campo della ricerca dell'attività β-glucosidasica in ceppi appartenenti alla specie S. uvarum, fin'ora poco esplorata.
Reference
Bonciani T., De Vero L., Giannuzzi E., Verspohl A. and Giudici P. (2018). Qualitative and quantitative screening of the β‐glucosidase activity in Saccharomyces cerevisiae and Saccharomyces uvarum strains isolated from refrigerated must. Lett. Appl. Microbiol. Accepted Manuscript. doi:10.1111/lam.1289
Exploration of genetic and phenotypic diversity within Saccharomyces uvarum for driving strain improvement in winemaking
No full textThe selection and genetic improvement of wine yeast is an ongoing process, since yeast strains should match new technologies in winemaking to satisfy evolving consumer preferences. A large genetic background is the necessary starting point for any genetic improvement programme. For this reason, we collected and characterized a large number of strains belonging to Saccharomyces uvarum. In particular, 70 strains were isolated from cold-stored must samples: they were identified and compared to S. uvarum strains originating from different collections, regarding fermentation profile, spore viability and stress response. The results demonstrate a large biodiversity among the new isolates, with particular emphasis to fermentation performances, genotypes and high spore viability, making the isolates suitable for further genetic improvement programmes. Furthermore, few of them are competitive with Saccharomyces cerevisiae and per se, suitable for wine fermentation, due to their resistance to stress, short lag phase and fermentation by-products
Molecular two-step strategy to select inter-species Saccharomyces hybrids
No full textHybridization is a common tool to improve yeast for wine industry. Using non-GE hybridization techniques a lot of attempts lead to failed mating which is mainly caused by low spore viability and haplo-selfing. This work proposed a two-step molecular strategy to validate inter-species Saccharomyces hybrids rapidly
Ectopic recombination in sex-determination system as a source of genetic variation in the diploid yeast Zygosaccharomyces sapae.
No full textSexual reproduction increases genetic variation, which is strongly advantageous under harsh environmental conditions, as it allows natural selection to proceed more effectively. The yeasts of the Zygosaccharomyces rouxii complex are relevant in food elaboration and spoilage due to their ability to cope with low water activity environments and are characterized by gene copy number variation, genome instability, and aneuploidy/allodiploidy (Solieri et al. 2013). The mating-type locus (MAT) is a hotspot for chromosome rearrangement in yeasts. Here, we investigated the genetic architecture of sex determinants, including MAT loci and HO endonuclease in Zygosaccharomyces sapae diploid strain ABT301T, belonging to the Z. rouxii complex. We cloned these genes through a DNA walking strategy and a characterization of the flanking regions, while the chromosome assignment was performed combining Southern blotting and PFGE-karyotyping. We identified three divergent mating type-like (MTL) α-idiomorph sequences, designated as ZsMTLα copies 1, 2, and 3, which encoded homologues of Z. rouxii CBS 732T MATα2 (aa sequence identity from 67.0 to 99.5%) and MATα1 (identity 81.5-99.5%). Cloning of MATa-idiomorph yielded one ZsMTLa locus encoding two Z. rouxii-like proteins, MATa1 and MATa2. ABT301T possesses two divergent HO genes encoding distinct endonucleases. Based on the cloned ZsMTLα and ZsMTLa idiomorphs flanking regions we discovered that Z. sapae ABT301T displays an aααα genotype lacking the HMR silent cassette. Additionally, four putative HML cassettes were identified, two harbouring the ZsMTLα copy 1 and the remaining containing ZsMTLα copies 2 and 3. In conclusion, our results show that the mating-type switching is responsible for hyper-mutation in Z. rouxii complex. The ectopic recombination underlying this process is an error-prone mechanism, which represents a possible source of genetic variation providing yeast progeny with phenotypic variability and adaptation to hostile environments
High-glutathione producing yeasts obtained by genetic improvement strategies: a focus on adaptive evolution approaches for novel wine strains
No full textGlutathione (GSH) is the most abundant non-protein thiol in living organisms. Due to its
important antioxidant role, it is widely used in medicine, as a food additive, and in the cosmetic
industry. Recently, GSH has received growing attention in winemaking because of its ability to
control oxidative spoilage damage and to protect various aromatic compounds. Indeed, GSH
concentration in wine is highly variable and several factors are involved in its regulation, ranging
from grape must to yeast fermentation activity. This short review aims at highlighting the common
genetic strategies, useful for obtaining wine yeasts with enhanced GSH production, paying particular
attention to the adaptive evolution approaches. Moreover, other strategies, such as random
mutagenesis, metabolic engineering and hybridization have been briefly reviewed with a stress on
both their strengths and weaknesses in terms of actual feasibility and acceptance by wine consumers
Unimore Microbial Culture Collection: a source for providing novel yeasts for winemaking.
No full textThe University of Modena and Reggio Emilia (UNIMORE) Microbial Culture Collection (UMCC) supplies authenticated strains and fundamental biological data for research and biotechnological application (www.umcc.unimore.it). More than 1600 yeast strains, isolated from must, wine, beer vinegar, sourdough and other fermented products are included in UMCC and are maintained by techniques that ensure preservation and long term genetic stability
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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