scholarly journals GENETIC HYBRIDIZATION AT THE UNLINKED THY AND STR LOCI OF STREPTOCOCCUS

Genetics ◽  
1975 ◽  
Vol 81 (2) ◽  
pp. 223-241
Author(s):  
Arnold W Ravin ◽  
Tapan Chakrabarti
Keyword(s):  
Relative Efficiency ◽  
Thymidylate Synthetase ◽  
Wild Type ◽  
Phenotypic Properties ◽  
Str Loci ◽  
The Cross ◽  
Number Of Classes ◽  
Donor Species ◽  
Original Donor ◽  
Hybrid Dna

ABSTRACT The sanguis and pneumoniae species of Streptococcus were used as recipients in transformations from str  + to str-r and from thy  - to thy  +. The str-r mutations in the two species had been previously shown to be allelic. Homology of the thy  - mutations in the two species was demonstrated in the similar phenotypic properties they conferred (death in the absence of thymidine, lack of thymidylate synthetase). The str and thy loci are unlinked in each species.——When the two species are transformed by both homospecific and heterospecific DNA, the efficiency is always lower in the heterospecific cross. The efficiency of heterospecific transformation is considerably lower at the thy than at the str locus. DNA was extracted from recipients that had integrated markers of heterospecific origin. When such hybrid DNA is tested on the original recipient species, the heterospecific markers are usually as efficient as homospecific markers. When tested on the original donor species, however, the hybrid DNA is usually more efficient than heterospecific DNA. This is true for both thy and str transformations.——Forty independent thy  + hybrids were obtained in the cross of sanguis thy  - recipients with pneumoniae thy  + DNA. These hybrids fall into a number of classes based upon the relative efficiency with which their extracted DNA's are able to transfer the thy  + marker into pneumoniae thy  - cells. The most efficient of these DNA's exhibits about 20% of the efficiency of homospecific pneumoniae thy  + DNA and three orders of magnitude greater efficiency than heterospecific sanguis thy  + DNA. Thus, very little of the inefficiency of heterospecific transformation of the thy locus is ascribable to a classic restriction mechanism. Rather, the wild-type thy  + loci in the two species appear to differ at multiple sites, and independent heterospecific transfers result in differential extents of integration of these sites. On this basis, the thy  + loci of the two species differ at a greater number of sites than do the respective str  + loci.

scholarly journals GENETIC RECOMBINATION AT THE BUFF SPORE COLOR LOCUS IN SORDARIA BREVICOLLIS. II. ANALYSIS OF FLANKING MARKER BEHAVIOR IN CROSSES BETWEEN BUFF MUTANTS

Genetics ◽  
1983 ◽  
Vol 103 (2) ◽  
pp. 161-178
Author(s):  
Helen Sang ◽  
Harold L K Whitehouse
Keyword(s):  
Genetic Recombination ◽  
Crossing Over ◽  
Wild Type ◽  
Equal Frequency ◽  
Proximal Site ◽  
The Cross ◽  
The Relationship ◽  
Aberrant Segregation ◽  
Distal Site ◽  
Hybrid Dna

ABSTRACT Aberrant asci containing one or more wild-type spores were selected from crosses between pairs of alleles of the buff locus in the presence of closely linked flanking markers. Data were obtained relating to the site of aberrant segregation and the position of any associated crossover giving recombination of flanking markers. Aberrant segregation at a proximal site within the buff gene may be associated with a crossover proximal to the site of aberrant segregation or, with equal frequency, with a crossover distal to the site of the second mutant present in the cross. Similarly, segregation at a distal site may be associated with a crossover distal to the site or, with lower frequency, with a crossover proximal to the site of the proximal mutant present in the cross. Crossovers between the alleles were rare. This evidence for the relationship between hybrid DNA and crossing over is discussed in terms of current models for the mechanism of recombination.

scholarly journals Recombination within the Y locus in Ascobolus immersus

1967 ◽  
Vol 9 (2) ◽  
pp. 159-177 ◽  
Author(s):  
A. Kruszewska ◽  
W. Gajewski
Keyword(s):  
Opposite Direction ◽  
Negative Correlation ◽  
Linear Order ◽  
Great Majority ◽  
Wild Type Allele ◽  
Wild Type ◽  
Marker Effect ◽  
Dna Models ◽  
Ascobolus Immersus ◽  
Hybrid Dna

Mutants of the Y locus differed appreciably in their basic conversion frequencies (frequencies of conversion in one-point crosses) to wild type. The differences in the basic conversion frequencies in the opposite direction, i.e. from corresponding wild-type allele to mutant, were in general not pronounced. For some alleles frequencies of conversion in both directions were similar, but for the others they differed markedly. No evident correlation between the position of mutants on the map and their basic conversion frequencies was observed.In two-point crosses in repulsion, the great majority of recombinant octads were of conversion type. In these crosses symmetry or asymmetry of conversion depended mainly on similarity or differences in basic conversion frequencies of mutants crossed. In crosses between mutants from different clusters the recombination frequencies were near to the sums of their basic conversion frequencies. Such ‘mutant specificity’ makes it impossible to establish the linear order of mutants on the basis of recombination frequencies in two-point crosses.The results of two-point crosses in repulsion between mutants within clusters pointed to the influence of one allele on the frequency of conversion of another one. This ‘marker effect’ was also evident in some three-point crosses.The frequencies of simultaneous conversions in two-point crosses in coupling did not show negative correlation with the distances between the mutants involved.It seems that many of the data presented here are most easily explained by recently developed hybrid DNA models.

scholarly journals A Point Mutation in the mma3 Gene Is Responsible for Impaired Methoxymycolic Acid Production in Mycobacterium bovis BCG Strains Obtained after 1927

2000 ◽  
Vol 182 (12) ◽  
pp. 3394-3399 ◽  
Author(s):  
Marcel A. Behr ◽  
Benjamin G. Schroeder ◽  
Jacquelyn N. Brinkman ◽  
Richard A. Slayden ◽  
Clifton E. Barry
Keyword(s):  
Point Mutation ◽  
Mycobacterium Bovis ◽  
Mycobacterium Smegmatis ◽  
Pasteur Institute ◽  
Wild Type ◽  
Phenotypic Properties ◽  
Site Specific ◽  
Mutant Population ◽  
Mycolic Acids

ABSTRACT BCG vaccines are substrains of Mycobacterium bovisderived by attenuation in vitro. After the original attenuation (1908 to 1921), BCG strains were maintained by serial propagation in different BCG laboratories (1921 to 1961). As a result, various BCG substrains developed which are now known to differ in a number of genetic and phenotypic properties. However, to date, none of these differences has permitted a direct phenotype-genotype link. Since BCG strains differ in their abilities to synthesize methoxymycolic acids and since recent work has shown that the mma3 gene is responsible for O-methylation of hydroxymycolate precursors to form methoxymycolic acids, we analyzed methoxymycolate production andmma3 gene sequences for a genetically defined collection of BCG strains. We found that BCG strains obtained from the Pasteur Institute in 1927 and earlier produced methoxymycolates in vitro but that those obtained from the Pasteur Institute in 1931 and later all failed to synthesize methoxymycolates, and furthermore, themma3 sequence of the latter strains differs from that ofMycobacterium tuberculosis H37Rv by a point mutation at bp 293. Site-specific introduction of this guanine-to-adenine mutation into wild-type mma3 (resulting in the replacement of glycine 98 with aspartic acid) eliminated the ability of this enzyme to produce O-methylated mycolic acids when the mutant was cloned in tandem with mma4 into Mycobacterium smegmatis. These findings indicate that a point mutation in mma3 occurred between 1927 and 1931, and that this mutant population became the dominant clone of BCG at the Pasteur Institute.

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 Comparative Study of the Roles of AhpC and KatE as Respiratory Antioxidants in Brucella abortus 2308

2010 ◽  
Vol 192 (19) ◽  
pp. 4912-4922 ◽  
Author(s):  
Kendra H. Steele ◽  
John E. Baumgartner ◽  
Michelle Wright Valderas ◽  
R. Martin Roop
Keyword(s):  
Brucella Abortus ◽  
Double Mutant ◽  
Aerobic Metabolism ◽  
The Other ◽  
Wild Type ◽  
Phenotypic Properties ◽  
Experimental Findings ◽  
Oxide Synthase ◽  
Derivatives Of ◽  
Inducible Nitric Oxide

ABSTRACT Brucella strains are exposed to potentially toxic levels of H2O2 both as a consequence of their aerobic metabolism and through the respiratory burst of host phagocytes. To evaluate the relative contributions of the sole catalase KatE and the peroxiredoxin AhpC produced by these strains in defense against H2O2-mediated toxicity, isogenic katE, ahpC, and katE ahpC mutants were constructed and the phenotypic properties of these mutants compared with those of the virulent parental strain B. abortus 2308. The results of these studies indicate that AhpC is the primary detoxifier of endogenous H2O2 generated by aerobic metabolism. KatE, on the other hand, plays a major role in scavenging exogenous and supraphysiologic levels of H2O2, although this enzyme can play a supporting role in the detoxification of H2O2 of endogenous origin if AhpC is absent. B. abortus ahpC and katE mutants exhibit wild-type virulence in C57BL/6 and BALB/c mice, but the B. abortus ahpC katE double mutant is extremely attenuated, and this attenuation is not relieved in derivatives of C57BL/6 mice that lack NADPH oxidase (cybb) or inducible nitric oxide synthase (Nos2) activity. These experimental findings indicate that the generation of endogenous H2O2 represents a relevant environmental stress that B. abortus 2308 must deal with during its residence in the host and that AhpC and KatE perform compensatory roles in detoxifying this metabolic H2O2.

scholarly journals Corresponding-site interference, synaptinemal complex structure, and 8+:0m and 7+:1m octads from wild-type × mutant crosses of Ascobolus immersus

1973 ◽  
Vol 22 (1) ◽  
pp. 113-124 ◽  
Author(s):  
B. C. Lamb ◽  
M. R. T. Wickramaratne
Keyword(s):  
Complex Structure ◽  
Wild Type ◽  
Synaptinemal Complex ◽  
Sister Chromatids ◽  
Ascobolus Immersus ◽  
Type Mutant ◽  
Hybrid Dna

SUMMARY‘Wider ratio’ octads (8:0, 0:8, 7:1 and 1:7) regularly occurred in wild-type(+) × white ascospore(w) crosses of the Pasadena strains of Ascobolus. Control crosses showed that phenocopies and false octad clusters were absent or rare; no reversion from w to + occurred, but mutation from + to w was found at a number of loci, with nearly all 0+:8w and many 2+:6w octads in + × w crosses arising from mutation, not conversion. Nearly all 8+:0w, 7+:1w and 6+:2w octads appeared to arise by conversion.The finding of genuine wider ratio octads implies hybrid-DNA formation at corresponding sites in both pairs of non-sister chromatids in the same bivalent, which conflicts with models of the synaptinemal complex requiring that only two of the four chromatids pair intimately at any point. Octad types arising from hybrid-DNA formation at corresponding sites in both pairs of non-sister chromatids were described and formulae were derived for their frequencies. The lack of genuine wider ratio octads in several other Ascobolus studies was shown to be explicable quantitatively in terms of their conversion frequencies.‘Corresponding-site interference’ is defined as interference between the two pairs of non-sister chromatids of a bivalent in hybrid-DNA formation at exactly corresponding sites. Formulae based on observed octad frequencies were derived for calculating coincidence values for this kind of interference. Corresponding-site interference was found to be weak, with coincidence values differing between crosses with high and with low conversion frequencies.

scholarly journals Phenotypic properties of R factors ofPseudomonas aeruginosa:R factors transferable only inPseudomonas aeruginosa

1974 ◽  
Vol 23 (3) ◽  
pp. 251-257 ◽  
Author(s):  
P. M. Chandler ◽  
V. Krishnapillai
Keyword(s):  
Drug Resistance ◽  
Shigella Flexneri ◽  
Low Frequency ◽  
Wild Type ◽  
Phenotypic Properties ◽  
Specific Phage ◽  
Group 2 ◽  
R Factors ◽  
Type Strains ◽  
Group 1

SUMMARYA study was made of the R factors from two multiply drug resistant wild type isolates ofPseudomonas aeruginosafrom a Birmingham hospital (Lowburyet al.1969) from which, in contrast to other strains from the same source (Chandler & Krishnapillai, 1974a), drug resistance was not transferable toEscherichia coliK12 orSalmonella typhimurium. Transfer of drug resistance occurred at a low frequency toShigella flexneri, although drug resistance in this species was subsequently non-transferable.InP. aeruginosathere are several features of these two R factors which distinguish them from the group 1 and 2 R factors described previously (Chandler & Krishnapillai, 1974a). Although coding for resistance to neomycin and tetracycline, they did not express this resistance in two strains ofP. aeruginosaexamined, in contrast to the wild type strains they were isolated in.The control of transfer of the two R factors is different to the group 1 and 2 R factors in that derepression of transfer could be demonstrated following physiological treatments or mutagenesis. The R factors of this third group were compatible with the group 2 R factors, but did not repress their pilus synthesis on the basis of R factor specific phage plating.

scholarly journals 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 Evidence that Mycobacterial PE_PGRS Proteins Are Cell Surface Constituents That Influence Interactions with Other Cells

2001 ◽  
Vol 69 (12) ◽  
pp. 7326-7333 ◽  
Author(s):  
Michael J. Brennan ◽  
Giovanni Delogu ◽  
Yiping Chen ◽  
Stoyan Bardarov ◽  
Jordan Kriakov ◽  
...  
Keyword(s):  
Cell Surface ◽  
Liquid Medium ◽  
Genomic Sequence ◽  
Wild Type ◽  
Phenotypic Properties ◽  
Transposon Insertion ◽  
Cell Surface Interactions ◽  
Type Gene ◽  
Aggregative Growth ◽  
Related Proteins

ABSTRACT The elucidation of the genomic sequence of Mycobacterium tuberculosis revealed the presence of a novel multigene family designated PE/PE_PGRS that encodes numerous, highly related proteins of unknown function. In this study, we demonstrate that a transposon insertion in a PE_PGRS gene (1818PE_PGRS) found inMycobacterium bovis BCG Pasteur, which is the BCG homologue of the M. tuberculosis H37Rv gene Rv1818c, introduces new phenotypic properties to this BCG strain. These properties include dispersed growth in liquid medium and reduced infection of macrophages. Complementation of the 1818PE_PGRS::Tn5367 mutant with the wild-type gene restores both aggregative growth (clumping) in liquid medium and reestablishes infectivity of macrophages to levels equivalent to those for the parent BCG strain. Western blot analysis using antisera raised against the 1818PE_PGRS protein shows that PE_PGRS proteins are found in cell lysates of BCG andM. tuberculosis H37Ra and in the cell wall fraction of M. tuberculosis H37Rv. Moreover, immunofluorescent labeling of mycobacteria indicates that certain PE_PGRS proteins are localized at the cell surface of BCG andM. tuberculosis. Together these results suggest that certain PE_PGRS proteins may be found at the surface of mycobacteria and influence both cell surface interactions among mycobacteria as well as the interactions of mycobacteria with macrophages.

scholarly journals Polarity of gene conversion and post-meiotic segregation at the buff locus in Sordaria brevicollis

1973 ◽  
Vol 22 (3) ◽  
pp. 279-289 ◽  
Author(s):  
D. J. Bond
Keyword(s):  
Gene Conversion ◽  
Meiotic Segregation ◽  
Wild Type ◽  
Heteroduplex Dna ◽  
Dna Models ◽  
Hybrid Dna

SUMMARYThe flanking markers of wild-type recombinant spores originating from crosses of spore colour mutants in Sordaria brevicollis were analysed. Recombinant asci were of two main types – either with one or with two wild-type spores. In most crosses the behaviour of flanking markers was significantly different for these two types of recombinant asci. The main differences were in the polarity of gene conversion (as inferred from parental outside marker combinations) and in the frequency of recombinant outside markers. These differences were interpreted in terms of hybrid DNA models of recombination and correction of heteroduplex DNA.

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