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Application of Yeast Genetics within the Brewing Industry. A Review. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-36-0175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Fusion ofSaccharomyces UvarumwithSaccharomyces Cerevisiae:Genetic Manipulation and Reconstruction of a Brewer's Yeast. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-38-0049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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Genetic instability in budding and fission yeast-sources and mechanisms. FEMS Microbiol Rev 2015; 39:917-67. [PMID: 26109598 PMCID: PMC4608483 DOI: 10.1093/femsre/fuv028] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2015] [Indexed: 12/17/2022] Open
Abstract
Cells are constantly confronted with endogenous and exogenous factors that affect their genomes. Eons of evolution have allowed the cellular mechanisms responsible for preserving the genome to adjust for achieving contradictory objectives: to maintain the genome unchanged and to acquire mutations that allow adaptation to environmental changes. One evolutionary mechanism that has been refined for survival is genetic variation. In this review, we describe the mechanisms responsible for two biological processes: genome maintenance and mutation tolerance involved in generations of genetic variations in mitotic cells of both Saccharomyces cerevisiae and Schizosaccharomyces pombe. These processes encompass mechanisms that ensure the fidelity of replication, DNA lesion sensing and DNA damage response pathways, as well as mechanisms that ensure precision in chromosome segregation during cell division. We discuss various factors that may influence genome stability, such as cellular ploidy, the phase of the cell cycle, transcriptional activity of a particular region of DNA, the proficiency of DNA quality control systems, the metabolic stage of the cell and its respiratory potential, and finally potential exposure to endogenous or environmental stress. The stability of budding and fission yeast genomes is influenced by two contradictory factors: (1) the need to be fully functional, which is ensured through the replication fidelity pathways of nuclear and mitochondrial genomes through sensing and repairing DNA damage, through precise chromosome segregation during cell division; and (2) the need to acquire changes for adaptation to environmental challenges.
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Protoplast fusion in a petite-negative yeast, Kluyveromyces lactis. Curr Genet 2013; 2:87-93. [PMID: 24189728 DOI: 10.1007/bf00445699] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/1980] [Indexed: 11/28/2022]
Abstract
The technique of protoplast fusion has been applied to the problem of unstable diploidy in the yeast Kluyveromyces lactis. By protoplast fusion between heterothallic strains of like mating-type, sporulation-deficient hybrids can be obtained. Biochemical, cytological, and genetical characterisation of these hybrids suggests that the majority of fusion products are diploid. Sporulating hybrids can be constructed by protoplast fusion between homothallic strains. Tetrad analysis of these hybrids demonstrates conclusively the diploid nature of fusion products.
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Hybridization of Saccharomyces cerevisiae with Candida utilis through protoplast fusion. Curr Genet 2013; 8:575-80. [PMID: 24177996 DOI: 10.1007/bf00395702] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/1984] [Indexed: 10/26/2022]
Abstract
Auxotrophic mutants of Saccharomyces cerevisiae and Candida utilis were hybridized through protoplast fusion. Spontaneous, UV- and FPA-induced mitotic segregation indicated that after cell fusion, exclusion of the S. cerevisiae nucleus or nuclear fusion followed by preferential loss of S. cerevisiae chromosomes can take place. Some of the hybrids were stable. One of them, expressed mating and sporulation functions of the S. cerevisiae parent. Thus, markers from both parents could be recovered as mitotic and meiotic segregants.
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Improved inhibitor tolerance in xylose-fermenting yeast Spathaspora passalidarum by mutagenesis and protoplast fusion. Appl Microbiol Biotechnol 2011; 93:2591-601. [DOI: 10.1007/s00253-011-3693-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 10/13/2011] [Accepted: 10/31/2011] [Indexed: 11/30/2022]
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Isolation and fusion of protoplasts from the phytopathogenic fungus sclerotium rolfsii(sacc.). Braz J Microbiol 2010; 41:253-63. [PMID: 24031488 PMCID: PMC3768609 DOI: 10.1590/s1517-838220100001000035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 08/23/2009] [Indexed: 11/22/2022] Open
Abstract
Sclerotium rolfsii (Sacc.) is a serious plant pathogenic fungus and lacks perfect (basidial) stage in production. Protoplast fusion technology was employed to reconstruct fusants from this fungus. Two strains designated as A and R were used. Maximum protoplast yields of 3.8x105/g mycelia and 2.8x105/g mycelia were formed in strains A and R respectively. Osmotic stabilizer sucrose 1M gave maximum yield. Lysing enzyme at the rate of 15mg/ml was found best for yield. Fusion of protoplasts from strains A and R was carried out in fusion media containing PEG 4000 30% (w/v) with 0.2mM CaCl2. Four fusants F1, F2, F3 and F4 were recovered. Morphological, physiological and pathogenic characters of fusants were compared with parent strains on carrots, beans and tomato.
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Characterization of Candida albicans colony-morphology mutants and their hybrids. Folia Microbiol (Praha) 2003; 48:203-9. [PMID: 12800504 DOI: 10.1007/bf02930957] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The collection wild-type strain of Candida albicans was used to obtain auxotrophic and colony-morphology mutants by 'nitrosoguanidine' treatment. Intraspecific protoplast fusion induced by Ca(2+)-poly(ethyleneglycol) was carried out in various pairings between the auxotrophic strain producing smooth colonies and containing blastospores and the colony-morphology mutants containing a mixture of blastospores and pseudohyphae or only hyphae. Hybrids exhibiting full or partial complementation were obtained when mutants producing smooth colonies and colony-morphology variants of different origins were fused. The mutation responsible for the colony-morphology character (if various types of colony morphomutants were crossed) proved to be recessive or semidominant. Representative hybrids exhibited elevated DNA contents as measured by flow cytometry. To illustrate various cell types, and especially the intermediate one (never observed in natural isolates), a preparation method was further developed for scanning electron microscopic studies.
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Intergeneric hybridization of Trichoderma reesei QM9414 and Saccharomyces cerevisiae NCIM 3288 by protoplast fusion. Enzyme Microb Technol 1994. [DOI: 10.1016/0141-0229(94)90062-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Occurrence of genetic segregation in a putative haploid strain of Endomyces fibuliger met by spontaneous sectoring of protoplast fusants. World J Microbiol Biotechnol 1994; 10:465-71. [PMID: 24421099 DOI: 10.1007/bf00144474] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/08/1994] [Accepted: 03/12/1994] [Indexed: 10/26/2022]
Abstract
Detailed genetic analysis of Endomyces fibuliger, an amylolytic yeast which is homothallic and exists predominantly in the diploid state, has not been performed. From a naturally occurring strain, E. fibuliger 8014 met, a morphological mutant, 193 met, was obtained by u.v. mutagenesis. To obtain a haploid strain suitable for genetic analysis, an intergeneric hybrid between E. fibuliger 193 met and a strain of a closely related dimorphic heterothallic lipolytic yeast, Yarrowia lipolytica, A his1, was produced by mass mating. The intergeneric hybrid was highly unstable in vegetative culture on yeast extract/phosphate/soluble starch/agar media and produced numerous mitotic sectors. Most of the sectors were mitotically unstable. However, one mitotically stable sector, N14i60 met, was obtained which also differed from the strain 193 as gauged by the appearance of DNA bands on pulsed-field gel electrophoresis. The putative haploid strain, N14i60 met, had six bands whilst the mutant 193 met had seven. Ultra-violet treatment of cells of N14i60 met produced 19 auxotrophic mutants. Protoplast fusion between pairs of different mutants showed complementation and the fusants were unstable mitotically and gave unstable aneuploid and stable haploid sectors of parental and non-parental combinations of markers. It is postulated that complementary diploid fusants, which were obtained by protoplast fusion, produced sectors by mitotic non-disjunction. Such a mechanism provides a means to establish a genetic analysis system for E. fibuliger via the parasexual cycle.
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Improvement of the cell volume ofCandida blankii through protoplast fusion. J Ind Microbiol Biotechnol 1992. [DOI: 10.1007/bf01583844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
This paper reports the initial experiments for genetic analysis of the haploid methylotrophic yeast Candida boidinii PLD1. The collection of multiply marked auxotrophic mutants was obtained after treatment with UV-light or X-rays. Protoplasts from several mutants were fused by the PEG-CA2+ technique and five prototrophic hybrids were isolated. The genetic structure of the hybrids was studied by means of spontaneous and induced mitotic segregation. Our data suggest that hybrids are diploids, heterozygous by parental auxotrophic markers. We obtained genetic linkage between mutations lys2-8-met-3 from one hand and ade-17-arg-24 from the other. The genetic maps constructed showed similar characteristics concerning both the order of the markers and their map distances.
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Interspecific protoplast fusion between Candida tropicalis and Candida boidinii: Characterization of the fusants. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0922-338x(91)90051-h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
An enrichment scheme using nystatin was designed for the isolation of auxotrophic mutants from the diploid-alkane-utilizing yeast Candida tropicalis. A collection of 194 auxotrophs representing 7 phenotypes was isolated. One class of mutants was identified as having a defect in histidinol dehydrogenase activity and a second class of mutants was identified as having a defect in orotidine monophosphate decarboxylase activity. These strains are good candidates to be carrying mutations corresponding to the HIS4 and URA3 genes of Saccharomyces cerevisiae.
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20
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Spectrophotometric determination of urea-ammonia in the urea degradation pathway of Saccharomyces cerevisiae. METHODS IN MICROBIOLOGY 1990. [DOI: 10.1016/0167-7012(90)90059-f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Interspecific complementation analysis by protoplast fusion of Candida tropicalis and Candida albicans adenine auxotrophs. J Bacteriol 1989; 171:3586-9. [PMID: 2722759 PMCID: PMC210094 DOI: 10.1128/jb.171.6.3586-3589.1989] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A protocol employing inositol starvation was used to isolate proline and adenine auxotrophs of Candida tropicalis. Interspecific hybrids between red adenine auxotrophs of C. tropicalis and Candida albicans were formed by protoplast fusion. These C. tropicalis red adenine auxotrophs were shown to fall into two complementation groups by crossing them with a known C. albicans ade1 tester strain. It is suggested that these two groups correspond to the ade1 and ade2 mutants of Saccharomyces cerevisiae and C. albicans and that these defined mutants may be useful in attempts to develop transformation systems for C. tropicalis.
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Abstract
Numerous methods based on classical genetics have been developed for the genetic mapping of yeasts. Recombinant DNA technology and technology for electrophoretic separation of chromosomes make new approaches possible. The state-of-the-art in genetic mapping of Saccharomyces cerevisiae will be briefly reviewed. Then the availability and application of genetic mapping methods to non-conventional yeasts will be surveyed. Development of the genetic maps of the asexual diploid Candida albicans and of the heterothallic yeast Yarrowia lipolytica will be discussed in more detail.
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Abstract
To date, more than 500 species of yeasts have been described. Most of the genetic and biochemical studies have, however, been carried out with Saccharomyces cerevisiae. Although a considerable amount of knowledge has been accumulated on fundamental processes and biotechnological applications of this industrially important yeast, the large variety of other yeast genera and species may offer various advantages for experimental study as well as for product formation in biotechnology. The genetic investigation of these so-called unconventional yeasts is poorly developed and information about corresponding data is dispersed. It is the aim of this review to summarize and discuss the main results of genetic studies and biotechnological applications of unconventional yeasts and to serve as a guide for scientists who wish to enter this field or are interested in only some aspects of these yeasts.
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Abstract
The present review is concerned with recent progress in basic genetic investigations with a variety of fungi which are pathogenic for man and animals. The principles and strategies involved in undertaking genetic investigations of sexual species and of asexual species are discussed. Progress in genetic analysis of Cryptococcus neoformans made possible by the discovery of its sexual phase is described in detail, as is progress in development of parasexual methods of analysis in Candida albicans. The genetic bases of virulence and drug resistance are discussed for those few species in which these phenotypes have been investigated. Suggestions for future research, including the application of recent advances in molecular biology to the study of pathogenic fungi, are presented.
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Spheroplast fusion of a brewing yeast strain with Saccharomyces diastaticus. Appl Microbiol Biotechnol 1985. [DOI: 10.1007/bf00295123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Evidence for the control of a mutation in lysine catabolism by the mating type in Yarrowia lipolytica. Curr Genet 1984; 8:531-6. [DOI: 10.1007/bf00410440] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/1984] [Indexed: 11/26/2022]
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Complementation and genetic inactivation: two alternative mechanisms leading to prototrophy in diploid bacterial clones. MOLECULAR & GENERAL GENETICS : MGG 1984; 196:488-93. [PMID: 6438446 DOI: 10.1007/bf00436197] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Evidence for diploidy at loci located all around the Bacillus subtilis chromosome previously led us to refer to the prototrophic bacterial clones produced by fusion of polyauxotrophic protoplasts as complementing diploid clones (Lévi-Meyrueis et al. 1980; Sanchez-Rivas 1982). In this paper, evidence is presented that gene inactivation may occur in such clones, as judged from the unequal expression of three unselected markers and their low transforming activity in cell lysates, an established property of inactivated genes (Bohin et al. 1982). The insensitivity to protease treatment of the lysates and also the low transforming activity observed with purified DNA may indicate that chromosome inactivation does not necessarily result from the mere attachment of proteins to DNA. Cotransfer by transformation of similarly expressed genes, initially located on separate chromosomes, suggests that genetic recombination has taken place, resulting in the reassortment of active and inactive genes on separate chromosomes. Several genetic structures compatible with the observations are presented which illustrate that prototrophy may result from such reassortment as well as from functional complementation.
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Genetic analysis of the yeastCandida maltosa by means of induced parasexual processes. Curr Microbiol 1984. [DOI: 10.1007/bf01567168] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Hybridization of yeasts by protoplast fusion: Ploidy level of hybrids resulting from fusions in haploid strains ofPichia guilliermondii. ACTA ACUST UNITED AC 1984. [DOI: 10.1002/jobm.3630240806] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Hybridization of yeasts by protoplast fusion: Early events after fusion inPichia guilliermondii. ACTA ACUST UNITED AC 1984. [DOI: 10.1002/jobm.3630240809] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Electro-fusion and genetic analysis of fusion products of haploid and polyploidSaccharomycesyeast cells. FEMS Microbiol Lett 1983. [DOI: 10.1111/j.1574-6968.1983.tb00080.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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35
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Ploidy reduction usingp-Fluorophenylalanine of fusion products ofSaccharomyces cerevisiae. Curr Microbiol 1983. [DOI: 10.1007/bf01567307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Interspecific protoplast fusion of Saccharomyces cerevisiae and Saccharomyces mellis. ACTA ACUST UNITED AC 1983. [DOI: 10.1007/bf00500499] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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37
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Yeast strain improvement by protoplast fusion and transformation. EXPERIENTIA. SUPPLEMENTUM 1983; 46:155-166. [PMID: 6325230 DOI: 10.1007/978-3-0348-6776-4_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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38
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39
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Cytoplasmic transfer of oligomycin resistance during protoplast fusion of Saccharomycopsis lipolytica. J Bacteriol 1982; 152:530-3. [PMID: 6749818 PMCID: PMC221459 DOI: 10.1128/jb.152.1.530-533.1982] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitotic segregation of oligomycin resistance and oligomycin sensitivity was observed among the prototrophic progeny of protoplast fusion between drug-resistant and drug-sensitive complementary auxotrophs of Saccharomycopsis lipolytica. The transfer of oligomycin resistance by protoplast fusion without karyogamy suggests a cytoplasmic inheritance of this drug resistance determinant.
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Genetic analysis of Candida albicans: identification of different isoleucine-valine, methionine, and arginine alleles by complementation. J Bacteriol 1982; 151:1247-52. [PMID: 7050083 PMCID: PMC220402 DOI: 10.1128/jb.151.3.1247-1252.1982] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
By using the spheroplast fusion technique as a tool for genetic analysis, we have demonstrated complementation among three of four isoleucine-valine mutants, two of three methionine mutants, and two arginine mutants of independent origin from two different Candida albicans isolates. The two adenine mutants derived from the same parent strain did not complement. Complementation resulted predominantly from heterokaryon formation and, in some cases, from heterozygote formation. In either case, most fusion products were unstable and showed nuclear as well as chromosomal segregation, in a few cases resulting in recombination of parental auxotrophic markers. However, some fusion products were fairly stable.
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Abstract
Auxotrophic mutants of C. albicans obtained by the method described by Henson and McClary (1979) were conditioned in a tris buffered EDTA-dithiothreitol solution then converted to protoplasts by suspension in osmotically stabilized buffer containing beta-glucuronidase. Complementary protoplasts were mixed in an osmotically stabilized polyethylene glycol solution and at appropriate times were plated respectively in osmotically stabilized minimal and complete agar media. From colony counts resulting from growth on the respective media, the proportion of fused complementary protoplasts (prototrophic colonies) to the total viable number of colony forming units was determined. Stability tests of selected colonies from the minimal and complete agar revealed multiple revertants, but the numbers declined to low frequencies upon repeated selective plating and isolation. Acridine orange staining of cultures thus stabilized revealed various sizes of cells with their numbers of nuclei (DNA-staining regions) varying from one to five, such that it was not determined whether the prototrophic cultures were monokaryons, heterokaryons or a mixture of the two.
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Abstract
Doubly auxotrophic strains of Candida albicans were selected from mutagenized cultures. Spheroplasts prepared from the auxotrophic strains were fused with polyethylene glycol. Prototrophic derivatives formed by this fusion protocol from auxotrophic strains were selected by complementation on minimal medium. These prototrophs had a cell volume twice that of the original strain and were shown to be heterozygous at four loci. Prototrophs obtained by this procedure infrequently gave rise to auxotrophic recombinants whose cell volume remained twice that of the original strain. It is suggested that these auxotrophic recombinants arise from mitotic crossing-over. This paper is the first report of a parasexual cycle in C. albicans.
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Sporulation of products of protoplast fusion without regeneration in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1981; 182:1-6. [PMID: 7022133 DOI: 10.1007/bf00422758] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In Saccharomyces cerevisiae, diploid strains which are respiratory deficient (e.g., rho-) or are homozygous for the mating-type locus (i.e., either a/a or alpha/alpha) are unable to sporulate. In order to induce sporulation in these nonsporulating strains, the technique of protoplast fusion mediated by polyethylene glycol was adopted. In this study, the products of protoplast fusion were induced to sporulate without reversion to normal cells. Protoplasts from a respiratory-deficient diploid strain were mixed with those from a respiratory-competent haploid one carrying mitochondrial drug resistance markers, treated with 30% polyethylene glycol-4000 and 25 mM CaCl2, and incubated in 0.1 M potassium acetate containing 0.8 M sorbitol as an osmotic stabilizer. After two days' incubation, asci with three to eight spores were formed at a frequency of 1 x 10(-3) to 2 x 10(-4). Sporulation was also observed in products of fusion between an a/a diploid and alpha haploid strains and between an alpha/alpha diploid and a haploid strains. The analysis of the genotypes of spores revealed that when fusion products were cultured under conditions for sporulation, karyogamy did not take place, diploid nuclei underwent meiosis, and both diploid and haploid nuclei were able to develop into spores.
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Abstract
Protoplasts of complementing auxotrophs of Candida albicans can fuse in the presence of polyethylene glycol and generate prototrophic cells. The yields of prototrophs from fusion mixtures depend greatly on the particular combinations of auxotrophies involved but not on other features of the strain backgrounds of protoplasts. The initial cellular products of fusions isolated on selective media are heterokaryons which replicate slowly but also segregate single parental nuclei into blastospores in high frequency. Karyogamy within heterokaryons produces hybrid nuclei which, on segregation, give rise to rapidly growing, uninucleate substrains. Analyses of the substrains show that hybrid nuclei either stabilize as diploid or undergo random loss of chromosomes to stabilize at various levels of aneuploidy prior to segregation. Chromosome losses and radiation induced mitotic crossing-over can effect recombination for parental auxotrophic markers in hybrids; patterns of recombination for ader and arg markers provide the first documented example of chromosomal linkage in C. albicans. Thus, protoplast fusions offer opportunities otherwise unavailable for applying the incisive tools of genetic recombination to analysis of this important, asexual yeast.
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Protoplast fusion — a tool for genetic manipulation and breeding in industrial microorganisms. Enzyme Microb Technol 1980. [DOI: 10.1016/0141-0229(80)90004-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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47
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Multiple fusion of protoplasts in Saccharomyces yeasts. MOLECULAR & GENERAL GENETICS : MGG 1979; 173:271-7. [PMID: 384149 DOI: 10.1007/bf00268637] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fusion of protoplasts prepared from haploid strains of Saccharomyces yeasts having identical mating type was induced with the aid of polyethylene glycol. Stable fusion products were isolated by complementation of the auxotrophic markers. Of 64 isolates derived by protoplast fusion between two different haploid strains having alpha mating type, 35 fusion products were estimated from their cell volumes to be diploid, 13 to be triploid and 16 to be tetraploid. The isolates showing tetraploid cell size were thought to have resulted from fusion of three protoplasts of one strain and one protoplast of the other (three-to-one fusion) or from two-to-two fusion. In protoplast fusion of three different haploid strains having alpha mating type, all four possible phenotypes of fusion product were recovered. Fusion products of three different protoplasts were obtained in much lower frequency (2.1 x 10(-6)) than those of two different protoplasts (1.2 x 10(-5) to 1.4 x 10(-4)) in the three other combinations. Genetic analyses revealed that triploid fusion products were formed by protoplast fusion of two different strains as well as of three different strains.
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