scholarly journals MUTATIONS AFFECTING SYNTHESIS OF β-GALACTOSIDASE ACTIVITY IN THE YEAST KLUYVEROMYCES LACTIS

Genetics ◽  
1980 ◽  
Vol 95 (4) ◽  
pp. 877-890
Author(s):  
R Michael Sheetz ◽  
Robert C Dickson
Keyword(s):  
Enzyme Activity ◽  
Kluyveromyces Lactis ◽  
Single Mutation ◽  
Chromosome 2 ◽  
Wild Type Allele ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Fold Level ◽  
Complementation Groups ◽  
Constitutive Synthesis

ABSTRACT Fifty-one mutants of Kluyveromyces lactis that cannot grow on lactose (Lac-) were isolated and characterized. All of the mutations are in nuclear genes, are recessive in their wild-type allele and define seven complementation groups, which we designate lac3 through lac9. Strains bearing mutations in lac3,lac5, lac7, lac8 and lac9 are also unable to grow on galactose (Gal-). Since the Gal- and Lac- phenotype co-segregate, they are probably due to a single mutation. Strains bearing mutations in any of the seven complementation groups grow normally on glucose. However, strains bearing mutations in lac3, lac5 and lac6 do not grow on glucose if lactose is also present in the medium. Likewise, strains bearing mutations in lac3 and lac5 do not grow on glucose in the presence of galactose. Complementation groups lac4 and lac5 are loosely linked and map within a cluster of auxotrophic mutations on a chromosome that we designate Chromosome 2. The remaining five groups are unlinked. Thus, there is no evidence for clustering of Lac genes into an operon-like regulatory unit.—To further characterize the nature of the Lac- phenotype, the basal and inducible level of β-galactosidase activity were measured. All mutants had nearly normal basal enzyme levels, except those in lac4, which had barely detectable levels. Inducible enzyme levels varied from barely detectable levels in mutants bearing lac4 mutations up to four-fold inducible levels in strains bearing mutations in other complementation groups. In all cases, however, induction levels were below the 30-fold level obtained in wild-type cells. Three strains bearing lac5 mutations contain increased enzyme activity in the absence of inducer, indicating constitutive synthesis of β-galactosidase. In summary, these data indicate that several genes are necessary for synthesis of β-galactosidase activity.

scholarly journals LAC4 IS THE STRUCTURAL GENE FOR β-GALACTOSIDASE IN KLUYVEROMYCES LACTIS

Genetics ◽  
1981 ◽  
Vol 98 (4) ◽  
pp. 729-745
Author(s):  
R Michael Sheetz ◽  
Robert C Dickson
Keyword(s):  
Thermal Stability ◽  
Structural Gene ◽  
Gel Electrophoresis ◽  
Kluyveromyces Lactis ◽  
Two Dimensional ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Nonsense Suppressor ◽  
Hydrolysis Of ◽  
Thermal Stability Of

ABSTRACT Using genetic and biochemical techniques, we have determined that β-galactosidase in the yeast Kluyveromyces lactis is coded by the LAC4 locus. The following data support this conclusion: (1) mutations in this locus result in levels of β-galactosidase activity 100-fold lower than levels in uninduced wild type and all other lac- mutants; (2) three of five lac4 mutations are suppressible by an unlinked suppressor whose phenotype suggests that it codes for a nonsense suppressor tRNA; (3) a Lac+ revertant, bearing lac4–14 and this unlinked suppressor, has subnormal levels of β-galactosidase activity, and the Km for hydrolysis of o-nitrophenyl-β, D-galactoside and the thermal stability of the enzyme are altered; (4) the level of β-galactosidase activity per cell is directly proportional to the number of copies of LAC4; (5) analysis of cell-free extracts of strains bearing mutations in LAC4 by two-dimensional acryl-amide gel electrophoresis shows that strains bearing lac4–23 and lac4–30 contain an inactive β-galactosidase whose subunit co-electrophoreses with the wild-type subunit, while no subunit or fragment of the subunit is obs0ervable in lac4–8, lac4–14 or lac4–29 mutants; (6) of all lac4 mutants, only those bearing lac4–23 or lac4–30 contain a protein that cross-reacts with anti-β-galactosidase antibody, a finding consistent with the previous result; and (7) β-galactosidase activity in several Lac+ revertants of strains carrying lac4–23 or lac4–30 has greatly decreased thermostability.

A conditional mutant having paralyzed cilia and a block in cytokinesis is rescued by cytoplasmic exchange in Tetrahymena thermophila.

Genetics ◽  
1988 ◽  
Vol 120 (3) ◽  
pp. 697-705
Author(s):  
D G Pennock ◽  
T Thatcher ◽  
J Bowen ◽  
P J Bruns ◽  
M A Gorovsky
Keyword(s):  
Energy Production ◽  
Complementation Group ◽  
Restrictive Temperature ◽  
Single Mutation ◽  
Wild Type ◽  
Alpha Tubulin ◽  
Ciliary Function ◽  
Conditional Mutant ◽  
Complementation Groups ◽  
Group 1

Abstract Nineteen mutants that are conditional for both the ability to regain motility following deciliation and the ability to grow were isolated. The mutations causing slow growth were placed into five complementation groups. None of the mutations appears to affect energy production as all mutants remained motile at the restrictive temperature. In three complementation groups protein synthesis and the levels of mRNA encoding alpha-tubulin or actin were largely unaffected at the restrictive temperature, consistent with the hypothesis that mutations in these three groups directly affect the assembly of functional cilia and growth. Complementation group 1 was chosen for further characterization. Both phenotypes were shown to be linked, suggesting they are caused by a single mutation. Group 1 mutants regenerated cilia at the restrictive temperature, but the cilia were nonmotile. This mutation also caused a block in cytokinesis at the restrictive temperature but did not affect nuclear divisions or DNA synthesis. The block in cell division was transiently rescued by wild-type cytoplasm exchanged when mutants were paired with wild-type cells during conjugation (round 1 of genomic exclusion). Thus, at least one mutation has been isolated that affects assembly of some microtubule-based structures in Tetrahymena (cilia during regeneration) but not others (nuclei divide at 38 degrees), and the product of this gene is likely to play a role in both ciliary function and in cytokinesis.

SOMATIC CONVERSION (PARAMUTATION) AT THE SULFUREA LOCUS OF LYCOPERSICON ESCULENTUM MILL. III. STUDIES WITH TRISOMICS

1969 ◽  
Vol 11 (2) ◽  
pp. 346-358 ◽  
Author(s):  
Rudolf Hagemann
Keyword(s):  
Lycopersicon Esculentum ◽  
Genetic Instability ◽  
Chromosome 2 ◽  
Wild Type Allele ◽  
Wild Type ◽  
Genetic Studies ◽  
Vegetative Cells ◽  
Type Allele ◽  
Primary Trisomics ◽  
Lycopersicon Esculentum Mill

Genetic studies carried out since 1958, have revealed at the sulfurea (sulf) locus of Lycopersicon esculentum the occurrence of a particular type of genetic instability: somatic conversion (paramutation). In vegetative cells of sulf+sulf heterozygotes the wild type allele sulf+ is heritably altered under the influence of the mutant sulf allele which is present in the same nucleus.By crossing sulf homozygotes and seven primary trisomics of the tomato (triplo-2, -5, -7, -8, -9, -10, -12) as well as a tertiary trisomic it was proven that the sulf locus is on chromosome 2, the nucleolus chromosome of the tomato.The effects of dosage are shown by the two different heterozygous trisomics which differ with regard to somatic conversion. In sulf+sulf sulf plants somatic conversion takes place very frequently; 60% of the plants (35) are variegated; that is, two conversion-active sulf alleles are very frequently able to convert one sensitive sulf+ allele. However, in sulf+sulf+sulf plants conversion has so far not been found; all plants (52) are entirely green; that is, one conversion-active sulf allele acting against two conversion-sensitive sulf+ alleles is not able to induce somatic conversion.

scholarly journals Genetic regulation: yeast mutants constitutive for beta-galactosidase activity have an increased level of beta-galactosidase messenger ribonucleic acid.

1981 ◽  
Vol 1 (11) ◽  
pp. 1048-1056 ◽  
Author(s):  
R C Dickson ◽  
R M Sheetz ◽  
L R Lacy
Keyword(s):  
Ribonucleic Acid ◽  
Transcription Initiation ◽  
Regulatory Element ◽  
Kluyveromyces Lactis ◽  
Mrna Level ◽  
Genetic Regulation ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Messenger Ribonucleic Acid ◽  
Beta Galactosidase

Mutants of Kluyveromyces lactis with elevated uninduced levels of beta-galactosidase (EC 32.1.2.3) activity, constitutive mutants (lac10c), were isolated and characterized to determine the basis for their constitutiveness. These lesions are not operator-type regulatory mutants because they are not closely linked to the beta-galactosidase structural gene. In a constitutive strain having a 7-fold increase in beta-galactosidase activity, the concentration of beta-galactosidase messenger ribonucleic acid (mRNA) was 8- to 10-fold higher than uninduced wild type. The half-life of beta-galactosidase mRNA was the same in the mutant strain (t1/2 = 4.5 +/- 0.2 min) as in uninduced wild-type cells (t1/2 = 4.8 +/- 0.1 min), indicating that the elevated mRNA level in the mutant was not due to a decreased rate of mRNA degradation. Consequently, we hypothesize that the LAC10 product regulates transcription of the beta-galactosidase gene; it probably affects the rate of transcription initiation. Parallel increases in enzyme protein, in constitutive levels of beta-galactosidase activity, and in mRNA further support this position, making translational or posttranslational control by LAC10 unlikely. Several types of data suggest that the LAC10 product functions as a negative regulatory element to prevent transcription. Other data demonstrate that lac10c mutations have pleiotrophic effects, there being constitutive levels not only of beta-galactosidase activity, but also the other lactose-inducible activities of galactokinase (EC 2.7.5.1), galactose-1-phosphate uridyl transferase (EC 2.7.7.10), and lactose transport. It would appear that LAC10 regulates lactose-inducible proteins.

Genetic regulation: yeast mutants constitutive for beta-galactosidase activity have an increased level of beta-galactosidase messenger ribonucleic acid

1981 ◽  
Vol 1 (11) ◽  
pp. 1048-1056
Author(s):  
R C Dickson ◽  
R M Sheetz ◽  
L R Lacy
Keyword(s):  
Ribonucleic Acid ◽  
Transcription Initiation ◽  
Regulatory Element ◽  
Kluyveromyces Lactis ◽  
Mrna Level ◽  
Genetic Regulation ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Messenger Ribonucleic Acid ◽  
Beta Galactosidase

Mutants of Kluyveromyces lactis with elevated uninduced levels of beta-galactosidase (EC 32.1.2.3) activity, constitutive mutants (lac10c), were isolated and characterized to determine the basis for their constitutiveness. These lesions are not operator-type regulatory mutants because they are not closely linked to the beta-galactosidase structural gene. In a constitutive strain having a 7-fold increase in beta-galactosidase activity, the concentration of beta-galactosidase messenger ribonucleic acid (mRNA) was 8- to 10-fold higher than uninduced wild type. The half-life of beta-galactosidase mRNA was the same in the mutant strain (t1/2 = 4.5 +/- 0.2 min) as in uninduced wild-type cells (t1/2 = 4.8 +/- 0.1 min), indicating that the elevated mRNA level in the mutant was not due to a decreased rate of mRNA degradation. Consequently, we hypothesize that the LAC10 product regulates transcription of the beta-galactosidase gene; it probably affects the rate of transcription initiation. Parallel increases in enzyme protein, in constitutive levels of beta-galactosidase activity, and in mRNA further support this position, making translational or posttranslational control by LAC10 unlikely. Several types of data suggest that the LAC10 product functions as a negative regulatory element to prevent transcription. Other data demonstrate that lac10c mutations have pleiotrophic effects, there being constitutive levels not only of beta-galactosidase activity, but also the other lactose-inducible activities of galactokinase (EC 2.7.5.1), galactose-1-phosphate uridyl transferase (EC 2.7.7.10), and lactose transport. It would appear that LAC10 regulates lactose-inducible proteins.

scholarly journals GAL4 of Saccharomyces cerevisiae activates the lactose-galactose regulon of Kluyveromyces lactis and creates a new phenotype: glucose repression of the regulon.

1987 ◽  
Vol 7 (2) ◽  
pp. 780-786 ◽  
Author(s):  
M I Riley ◽  
J E Hopper ◽  
S A Johnston ◽  
R C Dickson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Type Strain ◽  
Wild Type Strain ◽  
Glucose Repression ◽  
Kluyveromyces Lactis ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Fold Induction ◽  
Beta Galactosidase ◽  
Galactokinase Activity

A Kluyveromyces lactis mutant defective in lac9 cannot induce beta-galactosidase or galactokinase activity and is unable to grow on lactose or galactose. When this strain was transformed with the GAL4 positive regulatory gene of Saccharomyces cerevisiae it was able to grow on lactose or galactose as the sole carbon source. Transformants bearing GAL4 exhibited a 4.5-h generation time on galactose or lactose, versus 24 h for the nontransformed lac9 strain. A K. lactis lac9 strain bearing two integrated copies of GAL4 showed 3.5-fold induction of beta-galactosidase activity and 1.8-fold induction of galactokinase activity compared with 15.6-fold and 4.4-fold induction, respectively, for the LAC9 wild-type strain. In transformants bearing 10 integrated copies of GAL4, the induced level of beta-galactosidase was nearly as high as in the LAC9 wild-type strain. In addition to restoring lactose and galactose gene expression, GAL4 in K. lactis lac9 mutant cells conferred a new phenotype, severe glucose repression of lactose and galactose-inducible enzymes. Glucose repressed beta-galactosidase activity 35- to 74-fold and galactokinase activity 14- to 31-fold in GAL4 transformants, compared with the 2-fold glucose repression exhibited in the LAC9 wild-type strain. The S. cerevisiae MEL1 gene was repressed fourfold by glucose in LAC9 cells. In contrast, the MEL1 gene in a GAL4 lac9 strain was repressed 20-fold by glucose. These results indicate that the GAL4 and LAC9 proteins activate transcription in a similar manner. However, either the LAC9 or GAL4 gene or a product of these genes responds differently to glucose in K. lactis.

scholarly journals Genetic Analysis of Delta, a Neurogenic Gene of Drosophila melanogaster

Genetics ◽  
1987 ◽  
Vol 116 (3) ◽  
pp. 433-445
Author(s):  
Harald Vässin ◽  
Jose A Campos-Ortega
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Phenotypic Expression ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Embryonic Lethal ◽  
Complementation Groups ◽  
Interallelic Complementation ◽  
Hypomorphic Alleles

ABSTRACT We report here the results of a genetic analysis of the gene Delta (Dl) of Drosophila melanogaster. Dl has been mapped to the band 92A2, on the basis of two pieces of evidence: (1) this band is the common breakpoint of several chromosomal aberrations associated with Dl mutations and (2) recombination mapping of alleles of five different lethal complementation groups that are uncovered by Df(3R)DlFX3 (breakpoints at 91F11; 92A3). Dl was found to map most distally of all five complementation groups. The analysis of a large number of Dl alleles demonstrates the considerable genetic and functional complexity of Dl. Three types of Dl alleles are distinguishable. Most alleles behave as amorphic or hypomorphic recessive embryonic lethal alleles, which in addition cause various defects in heterozygosity over the wild-type allele. The defects are due to haplo-insufficient expression of the locus and can be suppressed by a duplication of the wild-type allele. The second class is comprised of three alleles with antimorphic expression. The phenotype of these alleles can only be reduced, rather than suppressed, by a duplication of the wild-type allele. The third group is comprised of three visible, predominantly hypomorphic alleles with an antimorphic component of phenotypic expression. The pattern of interallelic complementation is complex. On the one hand, there is a group of hypomorphic, fully penetrant embryonic lethal alleles which complement each other. On the other hand, most alleles, including all amorphic alleles, are viable over the visible ones; alleles of antimorphic expression, however, are lethal over visible alleles. These results are compatible with a rather complex genetic organization of the Dl locus.

GAL4 of Saccharomyces cerevisiae activates the lactose-galactose regulon of Kluyveromyces lactis and creates a new phenotype: glucose repression of the regulon

1987 ◽  
Vol 7 (2) ◽  
pp. 780-786
Author(s):  
M I Riley ◽  
J E Hopper ◽  
S A Johnston ◽  
R C Dickson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Type Strain ◽  
Wild Type Strain ◽  
Glucose Repression ◽  
Kluyveromyces Lactis ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Fold Induction ◽  
Beta Galactosidase ◽  
Galactokinase Activity

A Kluyveromyces lactis mutant defective in lac9 cannot induce beta-galactosidase or galactokinase activity and is unable to grow on lactose or galactose. When this strain was transformed with the GAL4 positive regulatory gene of Saccharomyces cerevisiae it was able to grow on lactose or galactose as the sole carbon source. Transformants bearing GAL4 exhibited a 4.5-h generation time on galactose or lactose, versus 24 h for the nontransformed lac9 strain. A K. lactis lac9 strain bearing two integrated copies of GAL4 showed 3.5-fold induction of beta-galactosidase activity and 1.8-fold induction of galactokinase activity compared with 15.6-fold and 4.4-fold induction, respectively, for the LAC9 wild-type strain. In transformants bearing 10 integrated copies of GAL4, the induced level of beta-galactosidase was nearly as high as in the LAC9 wild-type strain. In addition to restoring lactose and galactose gene expression, GAL4 in K. lactis lac9 mutant cells conferred a new phenotype, severe glucose repression of lactose and galactose-inducible enzymes. Glucose repressed beta-galactosidase activity 35- to 74-fold and galactokinase activity 14- to 31-fold in GAL4 transformants, compared with the 2-fold glucose repression exhibited in the LAC9 wild-type strain. The S. cerevisiae MEL1 gene was repressed fourfold by glucose in LAC9 cells. In contrast, the MEL1 gene in a GAL4 lac9 strain was repressed 20-fold by glucose. These results indicate that the GAL4 and LAC9 proteins activate transcription in a similar manner. However, either the LAC9 or GAL4 gene or a product of these genes responds differently to glucose in K. lactis.

scholarly journals cot1: A Regulator of Arabidopsis Trichome Initiation

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 565-577
Author(s):  
Daniel B Szymanski ◽  
Daniel A Klis ◽  
John C Larkin ◽  
M David Marks
Keyword(s):  
Cell Fate ◽  
Gene Dosage ◽  
Signal Transduction Pathway ◽  
Spatial Arrangement ◽  
Complex Signal ◽  
Chromosome 2 ◽  
Wild Type ◽  
Trichome Formation ◽  
In The Wild ◽  
Leaf Trichome

Abstract In Arabidopsis, the timing and spatial arrangement of trichome initiation is tightly regulated and requires the activity of the GLABROUS1 (GL1) gene. The COTYLEDON TRICHOME 1 (COT1) gene affects trichome initiation during late stages of leaf development and is described in this article. In the wild-type background, cot1 has no observable effect on trichome initiation. GL1 overexpression in wild-type plants leads to a modest number of ectopic trichomes and to a decrease in trichome number on the adaxial leaf surface. The cot1 mutation enhances GL1-overexpression-dependent ectopic trichome formation and also induces increased leaf trichome initiation. The expressivity of the cot1 phenotype is sensitive to cot1 and 35S::GL1 gene dosage, and the most severe phenotypes are observed when cot1 and 35S::GL1 are homozygous. The COT1 locus is located on chromosome 2 15.3 cM north of er. Analysis of the interaction between cot1, try, and 35S::GL1 suggests that COT1 is part of a complex signal transduction pathway that regulates GL1-dependent adoption of the trichome cell fate.

scholarly journals CYP2C19 Polymorphisms in Indonesia: Comparison among Ethnicities and the Association with Clinical Outcomes

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 300
Author(s):  
Muhammad Miftahussurur ◽  
Dalla Doohan ◽  
Ari Fahrial Syam ◽  
Iswan Abbas Nusi ◽  
Phawinee Subsomwong ◽  
...  
Keyword(s):  
Proton Pump Inhibitor ◽  
Clinical Outcomes ◽  
Proton Pump ◽  
Poor Metabolizers ◽  
Wild Type Allele ◽  
Wild Type ◽  
Type Allele ◽  
Sydney System ◽  
Intermediate Metabolizers ◽  
Cyp2c19 Polymorphisms

CYP2C19 polymorphisms are important factors for proton pump inhibitor-based therapy. We examined the CYP2C19 genotypes and analyzed the distribution among ethnicities and clinical outcomes in Indonesia. We employed the polymerase chain reaction-restriction fragment length polymorphism method to determine the CYP2C19 genotypes and evaluated inflammation severity with the updated Sydney system. For CYP2C19*2, 46.4% were the homozygous wild-type allele, 14.5% were the homozygous mutated allele, and 39.2% were the heterozygous allele. For CYP2C19*3, 88.6% were the homozygous wild-type allele, 2.4% were the homozygous mutated allele, and 9.0% were the heterozygous allele. Overall, the prevalence of rapid, intermediate, and poor metabolizers in Indonesia was 38.5, 41.6, and 19.9%, respectively. In the poor metabolizer group, the frequency of allele *2 (78.8%) was higher than the frequency of allele *3 (21.2%). The Papuan had a significantly higher likelihood of possessing poor metabolizers than the Balinese (OR 11.0; P = 0.002). The prevalence of poor metabolizers was lower compared with the rapid and intermediate metabolizers among patients with gastritis and gastroesophageal reflux disease. Intermediate metabolizers had the highest prevalence, followed by rapid metabolizers and poor metabolizers. Dosage adjustment should therefore be considered when administering proton pump inhibitor-based therapy in Indonesia.

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