scholarly journals A STUDY OF THE TRANSMISSION AND STRUCTURE OF DOUBLE STRANDED RNAs ASSOCIATED WITH THE KILLER PHENOMENON IN SACCHAROMYCES CEREVISIAE

Genetics ◽  
1976 ◽  
Vol 84 (1) ◽  
pp. 27-42
Author(s):  
T Kevin Sweeney ◽  
Ann Tate ◽  
Gerald R Fink
Keyword(s):  
Electron Microscopy ◽  
Saccharomyces Cerevisiae ◽  
The Other ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Mutant Strains ◽  
Different Types ◽  
Minus Strain

ABSTRACT Killer strains contain two double stranded RNAs, L and M. The M dsRNA appears to be necessary for production of a toxin and for resistance to that toxin. Mutant strains have been found that are defective in their ability to kill and in their resistance to toxin. These sensitive, non-killer strains have altered dsRNA composition. One class has no M dsRNA. Another class of sensitive, non-killers called suppressives has no M dsRNA but instead has smaller dsRNAs called S. In diploids resulting from a cross of a wild-type killer by a suppressive the transmission of the M dsRNA is suppressed by the S dsRNA. When a suppressive is crossed by a strain with no M dsRNA, the diploids and all four meiotic spores have the S dsRNA characteristic of the parental suppressive strain. Suppressive strains do not suppress each other. Intercrosses between two different suppressives yields diploids with both parental S dsRNAs. These two S dsRNAs are transmitted to all 4 meiotic progeny. Another class of mutants has been found which is defective for one of the traits but retains the other. One type, temperature-sensitive killers, has a normal dsRNA composition but is unable to kill at 30°. The other type, immunity-minus, has a complex dsRNA pattern. The immunity-minus strain is extremely unstable during mitotic growth and segregates several different types of non-killers. Analysis of the dsRNAs from wild type and the mutants by electron microscopy shows that the L, M, and S dsRNAs are linear. All strains regardless of killer phenotype appear to have the same size L dsRNA.

scholarly journals GENETICS OF YEAST HEXOKINASE

Genetics ◽  
1977 ◽  
Vol 86 (4) ◽  
pp. 727-744
Author(s):  
Zita Lobo ◽  
P K Maitra
Keyword(s):  
Saccharomyces Cerevisiae ◽  
The Other ◽  
Missense Mutations ◽  
Structural Genes ◽  
Wild Type ◽  
Hexokinase Activity ◽  
Mutant Strains ◽  
Mutant Genes ◽  
Yeast Hexokinase ◽  
Respective Wild Type

ABSTRACT Two independent isolates of Saccharomyces cerevisiae lacking hexokinase activity (EC 2.7.1.1) are described. Both mutant strains grow on glucose but are unable to grow on fructose, and contain two mutant genes h×k1 and h×k2 each. The mutations are recessive and noncomplementing. Genetic analysis suggests that these two unlinked genes h×k1 and h×k2 determine, independently of each other, the synthesis of hexokinase isozymes P1 and P2, respectively. h×k1 is located on chromosome VIR distal to met10, and h×k2 is on chromosome IIIR distal to MAL2. Of four hexokinase-positive spontaneous reversions, one is very tightly linked to h×k1 and the other three to the h×k2 locus. The reverted enzymes are considerably more thermolabile than the respective wild-type enzymes, and in one case show altered immunological properties. Data are presented which suggest that the h×k1 and h×k2 mutations are missense mutations in the structural genes of hexokinase P1 and hexokinase P2, respectively. These are presumably the only enzymes that allow S. cerevisiae to grow on fructose.

scholarly journals TWO CELL DIVISION CYCLE MUTANTS OF SACCHAROMYCES CEREVISIAE ARE DEFECTIVE IN TRANSMISSION OF MITOCHONDRIA TO ZYGOTES

Genetics ◽  
1982 ◽  
Vol 102 (1) ◽  
pp. 9-17
Author(s):  
Susan K Dutcher
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Nuclear Division ◽  
The Other ◽  
Temperature Sensitive ◽  
Gene Products ◽  
Wild Type ◽  
Mitochondrial Movement ◽  
Mitochondrial Transmission ◽  
Cdc Genes

ABSTRACT Mutations in CDC genes of S. cerevisiae disrupt the cell cycle at specific stages. The experiments reported here demonstrate that two CDC genes, CDC5 and CDC27, are necessary for mitochondrial segregation as well as for nuclear division. The defect in the transmission of mitochondria was revealed by the examination of uninucleate and binucleate progeny of transient heterokaryons generated by using the kar1-1 mutation that disrupts nuclear fusion. One of the parents lacked mitochondrial DNA (?0) whereas the other parent had functional mitochondria (?+). When the parents of the heterokaryon were both wild-type (CDC), nearly all progeny received mitochondria at 21° and at 34°. Thirty-four of the 36 cdc mutations tested had no defect in transmission of mitochondria to zygotic progeny in crosses in which one parent was a cdc mutant and the other parent was not (CDC). However, the cdc5 and cdc27 mutations prevented the transmission of mitochondria to cdc progeny at 34° but not at 21°; CDC progeny received mitochondria at either temperature. This defect was observed in crosses of cdc5 or cdc27 by wild-type cells regardless of which parent donated mitochondria to the zygote. The defect in mitochondrial transmission cosegregated in meiotic tetrads with the defect in mitosis demonstrating that both are likely to be caused by the same temperature-sensitive mutation. These results indicate that the CDC5 and CDC27 gene products are essential in two motility-related processes: mitochondrial movement from the zygote to the progeny and in mitosis.—Furthermore, the results suggest that the function performed by the CDC5 and CDC27 gene products for mitochondrial transmission differ in some fundamental way from the function performed for mitosis. The function necessary for mitosis can be supplied to the cdc5 (or cdc27) nucleus by the CDC5 (or CDC27) nucleus in the same heterokaryon but the function necessary for mitochondrial transmission cannot. Perhaps the function needed for mitochondrial transmission must be performed in the cell cycle preceding the actual segregation of mitochondria whereas the function needed for nuclear segregation can be performed at the time that mitosis occurs.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

scholarly journals act Operon Control of Developmental Gene Expression in Myxococcus xanthus

2002 ◽  
Vol 184 (4) ◽  
pp. 1172-1179 ◽  
Author(s):  
Thomas M. A. Gronewold ◽  
Dale Kaiser
Keyword(s):  
Fruiting Body ◽  
Myxococcus Xanthus ◽  
The Other ◽  
Loss Of Function ◽  
Wild Type ◽  
Developmental Gene ◽  
Developmental Gene Expression ◽  
Mutant Strains ◽  
Genes Encoding ◽  
Signal Production

ABSTRACT Cell-bound C-signal guides the building of a fruiting body and triggers the differentiation of myxospores. Earlier work has shown that transcription of the csgA gene, which encodes the C-signal, is directed by four genes of the act operon. To see how expression of the genes encoding components of the aggregation and sporulation processes depends on C-signaling, mutants with loss-of-function mutations in each of the act genes were investigated. These mutations were found to have no effect on genes that are normally expressed up to 3 h into development and are C-signal independent. Neither the time of first expression nor the rate of expression increase was changed in actA, actB, actC, or actD mutant strains. Also, there was no effect on A-signal production, which normally starts before 3 h. By contrast, the null act mutants have striking defects in C-signal production. These mutations changed the expression of four gene reporters that are related to aggregation and sporulation and are expressed at 6 h or later in development. The actA and actB null mutations substantially decreased the expression of all these reporters. The other act null mutations caused either premature expression to wild-type levels (actC) or delayed expression (actD), which ultimately rose to wild-type levels. The pattern of effects on these reporters shows how the C-signal differentially regulates the steps that together build a fruiting body and differentiate spores within it.

Translation in Saccharomyces cerevisiae: initiation factor 4E-dependent cell-free system

1989 ◽  
Vol 9 (10) ◽  
pp. 4467-4472
Author(s):  
M Altmann ◽  
N Sonenberg ◽  
H Trachsel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Point Mutations ◽  
Translation Initiation Factor ◽  
Apparent Temperature ◽  
Initiation Factor ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Free System ◽  
Gal1 Promoter

The gene encoding translation initiation factor 4E (eIF-4E) from Saccharomyces cerevisiae was randomly mutagenized in vitro. The mutagenized gene was reintroduced on a plasmid into S. cerevisiae cells having their only wild-type eIF-4E gene on a plasmid under the control of the regulatable GAL1 promoter. Transcription from the GAL1 promoter (and consequently the production of wild-type eIF-4E) was then shut off by plating these cells on glucose-containing medium. Under these conditions, the phenotype conferred upon the cells by the mutated eIF-4E gene became apparent. Temperature-sensitive S. cerevisiae strains were identified by replica plating. The properties of one strain, 4-2, were further analyzed. Strain 4-2 has two point mutations in the eIF-4E gene. Upon incubation at 37 degrees C, incorporation of [35S]methionine was reduced to 15% of the wild-type level. Cell-free translation systems derived from strain 4-2 were dependent on exogenous eIF-4E for efficient translation of certain mRNAs, and this dependence was enhanced by preincubation of the extract at 37 degrees C. Not all mRNAs tested required exogenous eIF-4E for translation.

Functional interaction between p21rap1A and components of the budding pathway in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (9) ◽  
pp. 4084-4092
Author(s):  
P C McCabe ◽  
H Haubruck ◽  
P Polakis ◽  
F McCormick ◽  
M A Innis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mammalian Cells ◽  
Bound States ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Amino Terminal ◽  
Loop Region

The rap1A gene encodes a 21-kDa, ras-related GTP-binding protein (p21rap1A) of unknown function. A close structural homolog of p21rap1A (65% identity in the amino-terminal two-thirds) is the RSR1 gene product (Rsr1p) of Saccharomyces cerevisiae. Although Rsr1p is not essential for growth, its presence is required for nonrandom selection of bud sites. To assess the similarity of these proteins at the functional level, wild-type and mutant forms of p21rap1A were tested for complementation of activities known to be fulfilled by Rsr1p. Expression of p21rap1A, like multicopy expression of RSR1, suppressed the conditional lethality of a temperature-sensitive cdc24 mutation. Point mutations predicted to affect the localization of p21rap1A or its ability to cycle between GDP and GTP-bound states disrupted suppression of cdc24ts, while other mutations in the 61-65 loop region improved suppression. Expression of p21rap1A could not, however, suppress the random budding phenotype of rsr1 cells. p21rap1A also apparently interfered with the normal activity of Rsrlp, causing random budding in diploid wild-type cells, suggesting an inability of p21rap1A to interact appropriately with Rsr1p regulatory proteins. Consistent with this hypothesis, we found an Rsr1p-specific GTPase-activating protein (GAP) activity in yeast membranes which was not active toward p21rap1A, indicating that p21rap1A may be predominantly GTP bound in yeast cells. Coexpression of human Rap1-specific GAP suppressed the random budding due to expression of p21rap1A or its derivatives, including Rap1AVal-12. Although Rap1-specific GAP stimulated the GTPase of Rsr1p in vitro, it did not dominantly interfere with Rsr1p function in vivo. A chimera consisting of Rap1A1-165::Rsr1p166-272 did not exhibit normal Rsr1p function in the budding pathway. These results indicated that p21rap1A and Rsr1p share at least partial functional homology, which may have implications for p21rap1A function in mammalian cells.

Isolation of the thymidylate synthetase gene (TMP1) by complementation in Saccharomyces cerevisiae

1982 ◽  
Vol 2 (4) ◽  
pp. 437-442
Author(s):  
G R Taylor ◽  
B J Barclay ◽  
R K Storms ◽  
J D Friesen ◽  
R H Haynes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Frequency ◽  
Wild Type Strain ◽  
Biologically Active ◽  
Thymidylate Synthetase ◽  
Temperature Sensitive ◽  
Synthetase Activity ◽  
Enzymatic Conversion ◽  
Wild Type ◽  
Sensitive Mutant

The structural gene (TMP1) for yeast thymidylate synthetase (thymidylate synthase; EC 2.1.1.45) was isolated from a chimeric plasmid bank by genetic complementation in Saccharomyces cerevisiae. Retransformation of the dTMP auxotroph GY712 and a temperature-sensitive mutant (cdc21) with purified plasmid (pTL1) yielded Tmp+ transformants at high frequency. In addition, the plasmid was tested for the ability to complement a bacterial thyA mutant that lacks functional thymidylate synthetase. Although it was not possible to select Thy+ transformants directly, it was found that all pTL1 transformants were phenotypically Thy+ after several generations of growth in nonselective conditions. Thus, yeast thymidylate synthetase is biologically active in Escherichia coli. Thymidylate synthetase was assayed in yeast cell lysates by high-pressure liquid chromatography to monitor the conversion of [6-3H]dUMP to [6-3H]dTMP. In protein extracts from the thymidylate auxotroph (tmp1-6) enzymatic conversion of dUMP to dTMP was barely detectable. Lysates of pTL1 transformants of this strain, however, had thymidylate synthetase activity that was comparable to that of the wild-type strain.

scholarly journals In VitroAdherence of Oral Bacteria to Different Types of Tongue Piercings

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Lucas Pereira Borges ◽  
Julio Cesar Campos Ferreira-Filho ◽  
Julia Medeiros Martins ◽  
Caroline Vieira Alves ◽  
Bianca Marques Santiago ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Adhesion ◽  
Oral Bacteria ◽  
The Other ◽  
Control Group ◽  
Colony Forming Units ◽  
Different Types ◽  
Scanning Electron

The purpose of this work was to verifyin vitroadherence ofE. corrodensandS. oralisto the surface of tongue piercings made of surgical steel, titanium, Bioplast, and Teflon. For this, 160 piercings were used for the count of Colony Forming Units (CFU) and 32 piercings for analysis under scanning electron microscopy. Of these, 96 (24 of each type) were individually incubated in 5 mL of BHI broth and 50 μL of inoculum at 37°C/24 h. The other 96 piercings formed the control group and were individually incubated in 5 mL of BHI broth at 37°C/24 h. Plates were incubated at 37°C/48 h for counting of CFU/mL and data were submitted to statistical analysis (pvalue<0.05). ForE. corrodens, difference among types of material was observed (p<0.001) and titanium and surgical steel showed lower bacterial adherence. The adherence ofS. oralisdiffered among piercings, showing lower colonization (p<0.007) in titanium and surgical steel piercings. The four types of piercings were susceptible to colonization byE. corrodensandS. oralis, and bacterial adhesion was more significant in those made of Bioplast and Teflon. The piercings presented bacterial colonies on their surface, being higher in plastic piercings probably due to their uneven and rough surface.

scholarly journals Mistranslating tRNA identifies a deleterious S213P mutation in the Saccharomyces cerevisiae eco1-1 allele

2020 ◽  
Vol 98 (5) ◽  
pp. 624-630 ◽  
Author(s):  
Yanrui Zhu ◽  
Matthew D. Berg ◽  
Phoebe Yang ◽  
Raphaël Loll-Krippleber ◽  
Grant W. Brown ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Genetic Disease ◽  
Elevated Temperatures ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Standard Genetic Code ◽  
Gene Encoding ◽  
Chromatid Cohesion ◽  
Sensitive Allele

Mistranslation occurs when an amino acid not specified by the standard genetic code is incorporated during translation. Since the ribosome does not read the amino acid, tRNA variants aminoacylated with a non-cognate amino acid or containing a non-cognate anticodon dramatically increase the frequency of mistranslation. In a systematic genetic analysis, we identified a suppression interaction between tRNASerUGG, G26A, which mistranslates proline codons by inserting serine, and eco1-1, a temperature sensitive allele of the gene encoding an acetyltransferase required for sister chromatid cohesion. The suppression was partial, with a tRNA that inserts alanine at proline codons and not apparent for a tRNA that inserts serine at arginine codons. Sequencing of the eco1-1 allele revealed a mutation that would convert the highly conserved serine 213 within β7 of the GCN5-related N-acetyltransferase core to proline. Mutation of P213 in eco1-1 back to the wild-type serine restored the function of the enzyme at elevated temperatures. Our results indicate the utility of mistranslating tRNA variants to identify functionally relevant mutations and identify eco1 as a reporter for mistranslation. We propose that mistranslation could be used as a tool to treat genetic disease.

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