scholarly journals EVIDENCE OF THE INSENSITIVITY OF THE α-inc ALLELE TO THE FUNCTION OF THE HOMOTHALLIC GENES IN SACCHAROMYCES YEASTS

Genetics ◽  
1979 ◽  
Vol 91 (2) ◽  
pp. 245-254
Author(s):  
Isamu Takano ◽  
Kenji Arima
Keyword(s):  
Cell Size ◽  
Mating Type ◽  
Diploid Cell ◽  
Tetrad Analysis ◽  
Type Allele ◽  
Fusion Of Protoplasts ◽  
Diploid Cells ◽  
Functional Combination ◽  
Fusion Products ◽  
Saccharomyces Yeasts

ABSTRACT The possible function of the α-inc allele (an α mating-type allele that is insensitive to the function of the homothallic gene system) was investigated by means of protoplast fusion. The fusion of protoplasts prepared from haploid strains of α-inc  HO HMα HMa and α ho hmα HMa gave rise mainly to nonmating clones (58 of 64 isolates) and a few clones (six of 64 isolates) showing a mating type. Thirty of the 56 nonmating clones showed the diploid cell size and 28 clones had a larger cell size. Tetrad analysis of the nonmating clones with diploid cell size indicated that they were a/α-inc diploid; the normal α allele in α/α-inc cells was preferentially switched to an a allele. This observation further indicated that the HO/ho HMα/hmα HMa/HMa genotype is effective for the conversion of the α to a and that the inconvertibility of the a-inc allele is due to the insensitivity of the mating-type allele to the functional combination of the homothallic genes. It was suspected that fusion products larger than diploid cells might have been caused by multiple fusion of protoplasts.

scholarly journals EVIDENCE FOR CO-DOMINANCE OF THE HOMOTHALLIC GENES, HMα/hmα AND HM  a/hm  a, IN SACCHAROMYCES YEASTS

Genetics ◽  
1979 ◽  
Vol 93 (1) ◽  
pp. 1-12
Author(s):  
Kenji Arima ◽  
Isamu Takano
Keyword(s):  
Mating Type ◽  
Mating Types ◽  
Type Conversion ◽  
Fusion Of Protoplasts ◽  
Fusion Products ◽  
Saccharomyces Yeasts

ABSTRACT To investigate the dominance and recessiveness of the homothallism genes, HMα/hmα and HMa/hma, for mating-type conversion, we constructed hybrids with various configurations of the homothallic genes by fusion of protoplasts prepared from haploid strains having identical mating types. Eight different combinations of the homothallic genes were tested for their function by observing the mating and sporulation abilities of the fusion products. With few exceptions, nonmating and sporogenous fusion products were obtained from the following combinations: α HO hmα  HMa + α ho hmα hma, α HO hmα HMa + α ho HMα hma, α HO hmα HMa + α ho HMα HMa, α HO HMα hma + a ho hmα hma, a HO HMα hma + a ho hmα HMa and a HO HMα hma + α ho HMα HMa. All the fusion products from the α HO hmα HMa + α ho hmα HMa and a HO HMα hma + a ho HMα hma combinations showed mating types identical to those of the respective haploid strains. These results clearly support the co-dominance of the HMα/hmα and HMa/hma alleles and indicate that the hmα allele has the same function as the HMa allele and that the hma allele has the same function as the HMα allele.

scholarly journals Creation of Stable Heterothallic Strains ofKomagataella phaffiiEnables Dissection of Mating Gene Regulation

2017 ◽  
Vol 38 (2) ◽  
Author(s):  
Lina Heistinger ◽  
Brigitte Gasser ◽  
Diethard Mattanovich
Keyword(s):  
Gene Regulation ◽  
Mating Type ◽  
Cell Formation ◽  
Methylotrophic Yeast ◽  
Diploid Cell ◽  
Mating Types ◽  
Inverted Repeat Region ◽  
Position Effects ◽  
Content Type ◽  
Diploid Cells

ABSTRACTThe methylotrophic yeastKomagataella phaffii(Pichia pastoris) is homothallic and has been reported to switch mating type by an ancient inversion mechanism. Two mating-type (MAT) loci include homologs of theMATaandMATα transcription factor genes, with the expression from one locus downregulated by telomere position effects. However, not much is known about mating gene regulation, since the mixture of mating types complicates detailed investigations. In this study, we developedK. phaffiistrains with stable mating types by deletion of the inverted-repeat region required for mating-type switching. These heterothallic strains retain their ability to mate with cells of the opposite mating type and were used to further elucidate mating gene regulation. Functional analysis ofMATmutant strains revealed the essential role ofMATa2andMATα1in diploid cell formation. Disruption ofMATa1orMATα2did not affect mating; however, in diploid cells, both genes are required for sporulation and the repression of shmoo formation. The heterothallic strains generated in this study allowed the first detailed characterization of mating gene regulation inK. phaffii. They will be a valuable tool for further studies investigating cell-type-specific behavior and will enable in-depth genetic analyses and strain hybridization in this industrially relevant yeast species.

scholarly journals MATING-TYPE DIFFERENTIATION BY TRANSPOSITION OF CONTROLLING ELEMENTS IN SACCHAROMYCES CEREVISIAE

Genetics ◽  
1981 ◽  
Vol 97 (3-4) ◽  
pp. 531-549
Author(s):  
Takehiro Oshima ◽  
Isamu Takano
Keyword(s):  
Mating Type ◽  
Cell Types ◽  
Mutant Clone ◽  
Genetic Trait ◽  
Type Locus ◽  
Type Allele ◽  
Mating Type Locus ◽  
Controlling Elements ◽  
Diploid Cells ◽  
Type Information

ABSTRACT The nonfunctional mutation of the homothallic gene HMLα, designated hmlα, produced two mutant alleles, hmlα-1 and hmlα-2. Both mutant clones were mixed cultures consisting of a mating-type cells and nonmating haploid cells. The frequencies of the two cell types were different, and a few diploid cells able to sporulate were found in the hmlα-2 mutant. Conversions of an a mating-type cell to nonmater, and uice uersa, were observed in both mutants. The conversion of an a mating phenotype to nonmating is postulated to occur by alteration of the a mating type to the sterile mating-type allele in the hmlα-1 mutant. In tetrad dissection of prototrophic diploids that were obtained by rare-mating of hmlα-1 mutants with a heterothallic strain having the MATa ho HMRa HMLa genotype, many mating-deficient haploid segregants were found, while α mating-type segregants were observed in a similar diploid using an hmlα-2 mutant. The mating-type-deficient haploid segregants were supposed to have the sterile a mating-type allele because the nonmating genetic trait always segregated with the mating-type locus. Sporogenous diploid cells obtained in the hmlα-2 mutant clone had the MATa/MAT,α HO/HO HMRa/ HMRa hmlα-2/hmlα-2 genotype. These observations suggested that the hmla-I allele produces a transposable element that gives rise to the sterile su mating type by transposition into the mating-type locus, and that the hmlα-2 allele produces an element that provides,α mating-type information, but is defective in the structure for transposition.

scholarly journals Mating Type in Chlamydomonas Is Specified by mid, the Minus-Dominance Gene

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 859-869 ◽  
Author(s):  
Patrick J Ferris ◽  
Ursula W Goodenough
Keyword(s):  
Transcription Factor ◽  
Mating Type ◽  
Codon Bias ◽  
Leucine Zipper ◽  
Laboratory Strain ◽  
Leucine Zipper Motif ◽  
Type Locus ◽  
Diploid Cells ◽  
Necessary And Sufficient

Diploid cells of Chlamydomonas reinhardtii that are heterozygous at the mating-type locus (mt  +/mt  –) differentiate as minus gametes, a phenomenon known as minus dominance. We report the cloning and characterization of a gene that is necessary and sufficient to exert this minus dominance over the plus differentiation program. The gene, called mid, is located in the rearranged (R) domain of the mt  – locus, and has duplicated and transposed to an autosome in a laboratory strain. The imp11 mt  – mutant, which differentiates as a fusion-incompetent plus gamete, carries a point mutation in mid. Like the fus1 gene in the mt  + locus, mid displays low codon bias compared with other nuclear genes. The mid sequence carries a putative leucine zipper motif, suggesting that it functions as a transcription factor to switch on the minus program and switch off the plus program of gametic differentiation. This is the first sex-determination gene to be characterized in a green organism.

Mating type control in Saccharomyces cerevisiae: a frameshift mutation at the common DNA sequence, X, of the HML alpha locus

1984 ◽  
Vol 4 (1) ◽  
pp. 203-211
Author(s):  
K Tanaka ◽  
T Oshima ◽  
H Araki ◽  
S Harashima ◽  
Y Oshima
Keyword(s):  
Mating Type ◽  
Base Pair ◽  
Reading Frame ◽  
Base Pair Deletion ◽  
A Cell ◽  
Alpha Gene ◽  
The Common ◽  
Type Switch ◽  
Diploid Cells ◽  
Mat Locus

A mutation defective in the homothallic switching of mating type alleles, designated hml alpha-2, has previously been characterized. The mutation occurred in a cell having the HO MATa HML alpha HMRa genotype, and the mutant culture consisted of ca. 10% a mating type cells, 90% nonmater cells of haploid cell size, and 0.1% sporogenous diploid cells. Genetic analyses revealed that nonmater haploid cells have a defect in the alpha 2 cistron at the MAT locus. This defect was probably caused by transposition of a cassette originating from the hml alpha-2 allele by the process of the homothallic mating type switch. That the MAT locus of the nonmater cells is occupied by a DNA fragment indistinguishable from the Y alpha sequence in electrophoretic mobility was demonstrated by Southern hybridization of the EcoRI-HindIII fragment encoding the MAT locus with a cloned HML alpha gene as the probe. The hml alpha-2 mutation was revealed to be a one-base-pair deletion at the ninth base pair in the X region from the X and Y boundary of the HML locus. This mutation gave rise to a shift in the open reading frame of the alpha 2 cistron. A molecular mechanism for the mating type switch associated with the occurrence of sporogenous diploid cells in the mutant culture is discussed.

scholarly journals The intron-containing gene for yeast profilin (PFY) encodes a vital function

1988 ◽  
Vol 8 (12) ◽  
pp. 5108-5115
Author(s):  
V Magdolen ◽  
U Oechsner ◽  
G Müller ◽  
W Bandlow
Keyword(s):  
Diploid Cell ◽  
Single Copy ◽  
Actin Binding ◽  
Gene Copy ◽  
Tetrad Analysis ◽  
Vital Function ◽  
Primary Transcript ◽  
Gene Coding ◽  
Gene Maps ◽  
Coding Capacity

The gene coding for profilin (PFY), an actin-binding protein, occurs as a single copy in the haploid genome of Saccharomyces cerevisiae and is required for spore germination and cell viability. Displacement of one gene copy in a diploid cell by a nonfunctional allele is recessively lethal: tetrad analysis yields only two viable spores per ascus. The PFY gene maps on chromosome XV and is linked to the ADE2 marker. The primary transcript of about 1,000 bases contains an intron of 209 bases and is spliced into a messenger of about 750 bases. The intron was identified by comparison with a cDNA clone, which also revealed the 3' end of the transcript. The 5' end of the mRNA was mapped by primer elongation. The gene is transcribed constitutively and has a coding capacity for a protein of 126 amino acids. The deduced molecular weight of

scholarly journals MUTATIONS INCREASING ASEXUAL PLASMODIUM FORMATION IN PHYSARUM POLYCEPHALUM

Genetics ◽  
1977 ◽  
Vol 87 (3) ◽  
pp. 401-420
Author(s):  
Paul N Adler ◽  
Charles E Holt
Keyword(s):  
Life Cycle ◽  
Mating Type ◽  
Physarum Polycephalum ◽  
The Other ◽  
Type Allele ◽  
Cold Sensitive ◽  
The One

ABSTRACT Rare plasmodia formed in clones of heterothallic amoebae were analyzed in a search for mutations affecting plasmodium formation. The results show that the proportion of mutants varies with both temperature (18°, 26° or 30°) and mating-type allele (mt1, mt2, mt3, mt4). At one extreme, only one of 33 plasmoida formed by mt2 amoebae at 18° is mutant. At the other extreme, three of three plasmodia formed by mt1 amoebae at 30° are mutant. The mutant plasmodia fall into two groups, the GAD (greater asexual differentiation) mutants and the ALC (amoebaless life cycle) mutants. The spores of GAD mutants give rise to amoebae that differentiate into plasmodia asexually at much higher frequencies than normal heterothallic amoebae. Seven of eight gad mutations analyzed genetically are linked to mt and one (gad-12) is not. The gad-12 mutation is expressed in strains with different alleles of mt. The frequency of asexual plasmodium formation is heat sensitive in some (e.g., mt3 gad-11), heat-insensitive in two (mt2 gad-8 and mt2 gad-9) and cold-sensitive in one (mt1 gad-12) of twelve GAD mutants analyzed phenotypically. The spores of ALC mutants give rise to plasmodia directly, thereby circumventing the amoebal phase of the life cycle. Spores from five of the seven ALC mutants give rise to occasional amoebae, as well as plasmodia. The amoebae from one of the mutants carry a mutation (alc-1) that is unlinked to mt and is responsible for the ALC phenotype in this mutant. Like gad-12, alc-1 is expressed with different mt alleles. Preliminary observations with amoebae from the other four ALC mutants suggest that two are similar to the one containing alc-1; one gives rise to revertant amoebae, and one gives rise to amoebae carrying an alc mutation and a suppressor of the mutation.

Regulation of STA1 gene expression by MAT during the life cycle of Saccharomyces cerevisiae

1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998
Author(s):  
A M Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Yeast Cells ◽  
Specific Gene ◽  
Activity Levels ◽  
Sporulation Medium ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Diploid Cells

STA1 encodes a secreted glucoamylase of the yeast Saccharomyces cerevisiae var. diastaticus. Glucoamylase secretion is controlled by the mating type locus MAT; a and alpha haploid yeast cells secrete high levels of the enzyme, but a/alpha diploid cells produce undetectable amounts. It has been suggested that STA1 is regulated by MATa2 (I. Yamashita, Y. Takano, and S. Fukui, J. Bacteriol. 164:769-773, 1985), which is a MAT transcript of previously unknown function. In contrast, this work shows that deletion of the entire MATa2 gene had no effect on STA1 regulation but that deletion of MATa1 sequences completely abolished mating-type control. In all cases, glucoamylase activity levels reflected STA1 mRNA levels. It appears that STA1 is a haploid-specific gene that is regulated by MATa1 and a product of the MAT alpha locus and that this regulation occurs at the level of RNA accumulation. STA1 expression was also shown to be glucose repressible. STA1 mRNA was induced in diploids during sporulation along with SGA, a closely linked gene that encodes an intracellular sporulation-specific glucoamylase of S. cerevisiae. A diploid strain with a MATa1 deletion showed normal induction of STA1 in sporulation medium, but SGA expression was abolished. Therefore, these two homologous and closely linked glucoamylase genes are induced by different mechanisms during sporulation. STA1 induction may be a response to the starvation conditions necessary for sporulation, while SGA induction is governed by the pathway by which MAT regulates sporulation. The strain containing a complete deletion of MATa2 grew, mated, and sporulated normally.

scholarly journals The expanding implications of polyploidy

2015 ◽  
Vol 209 (4) ◽  
pp. 485-491 ◽  
Author(s):  
Kevin P. Schoenfelder ◽  
Donald T. Fox
Keyword(s):  
Cell Size ◽  
Recent Progress ◽  
Environmental Stresses ◽  
Polyploid Cells ◽  
Diploid Cells ◽  
Metabolic Output

Polyploid cells, which contain more than two genome copies, occur throughout nature. Beyond well-established roles in increasing cell size/metabolic output, polyploidy can also promote nonuniform genome, transcriptome, and metabolome alterations. Polyploidy also frequently confers resistance to environmental stresses not tolerated by diploid cells. Recent progress has begun to unravel how this fascinating phenomenon contributes to normal physiology and disease.

Interspecific actions of ? mating pheromones on the a mating-type cells of three Saccharomyces yeasts

1988 ◽  
Vol 13 (1) ◽  
pp. 25-27 ◽  
Author(s):  
T. Hisatomi ◽  
N. Yanagishima ◽  
A. Sakurai ◽  
H. Kobayashi
Keyword(s):  
Mating Type ◽  
Mating Pheromones ◽  
Saccharomyces Yeasts
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