Biochemical Mutants Research Articles

Biochemical Mutant Strains of Neurospora Produced by Physical and Chemical Treatment

ancestors were, with axillaris and violacea being suspect. However, for those desiring a complete hierarchy the following might be used: Petunia gh. Hybrida ln. Rosy Morn. Here the admittedly spurious specific epithet, P. hybrida (which would imply the presence of a natural species), would be transferred to the category of (grex-hybrida), signifying a group of garden hybrids with a presumed common set of ancestors [see paragraph (c) for grex-hybrida]. (b) The clone: essentially uniform material derived from a single individual and propagated entirely by vegetative means, as by cuttings, divisions, grafts, etc. The epithet would be prefixed by the word (abbreviated as cl.), or indicated by the symbol t Examples: Pelargonium zonale < Mrs. Pollock; Syringa vulgaris cl. Decaisne, or for brevity, Syringa cl. Decaisne; Rhododendron cl. Flamboyant; Picea pungens var. glauca clone H. Montgomery. (c) The hybrid-group: a group of hybrids originating from the same parents or series of parents, but whose individuals vary in appearance; the group would be delimited by the potential variations inherent in the parental stocks. The epithet would be prefixed by the hyphenated words hybrid-group (Latin, grex-hybrida, abbreviated as gh.). Examples: Rhododendron gh. [the Ghent azaleas, sometimes listed as R. gandavense and recorded as the highly variable backcrosses and segregates of luteurn X (calendulaceum X nudiflorum) X viscosum X arborescens]; for greater precision a particular clone of this group would be listed as Rhododendron gh. cl. Flamboyant; Rosa gh. Hybrid Tea; Dahlia gh. Double Decorative. (d) The line-hybrid: a predictably uniform group derived by repetitive hybridization from a series of two or more constantly maintained breeding stocks, these parental lines being maintained either by continued inbreeding or as clones. The epithet, or identifying symbol or number, would be prefixed by the hyphenated words line-hybrid (Latin, linea-hybrida, abbreviated as lh.). Examples: This is the standard practice in the hybrid seed industry-e.g., United States Department of Agriculture, seed No. 13 (usually abbreviated as hybrid corn, US-13) -which, for greater precision in formal, international literature where the word corn has various applications, might be listed as Zea mays lh. US-13. This method also is an increasingly common practice in the production of ornamentalse.g., some of the so-called named and of Lilium offered for sale in large lots while yet seedlings (which, biologically, are neither races nor varieties but controlled hybrids derived from particular combinations between clonally maintained parental lines), the lots presumably virus-free and predictably uniform in ultimate color of flower and plant habit, including season of bloom.

THE USE OF ISOTOPIC CARBON IN A STUDY OF THE METABOLSIM OF ANTHRANILIC ACID IN NEUROSPORA

The finding by Tatum, Banner, and Beadle (l), that the tryptophanless Neurospora mutant strain 10575 accumulates anthranilic acid, which in turn can be utilized for growth of strain 40008, has provided evidence that anthranilic acid is a biochemical precursor of tryptophan in this organism. It has been further established that indole is an intermediate in this conversion (2-5). More recent work with a number of mutants of Neurospora (6-8) has established that tryptophan is a biochemical precursor to niacin with kynurenine and hydroxyanthranilic acid as intermediates. The accumulated evidence has indicated the existence in the mold of the following series of reactions: → Anthranilic acid → indole → tryptophan → kynurenine → 3-hydroxyanthranilic acid → nicotinic acid In the light of this evidence the present work was undertaken to trace the carbon in the carboxyl group of anthranilic acid in order to estimate its contribution as a structural unit in the formation of niacin and tryptophan. The organism chosen for this investigation was a biochemical mutant strain of Neurospora designated as strain 40008. This mutant utilizes anthranilic acid, indole, or tryptophan for growth. The mutant was grown in the presence of anthranilic acid containing Cl4 in the carboxyl group. Niacin and tryptophan were isolated from the mold mycelium and tested for radioactivity.

A Photographic Technique for the Detection of Presumptive Biochemical Mutants

A Photographic Technique for the Detection of Presumptive Biochemical Mutants

A Photographic Technique for the Detection of Presumptive Biochemical Mutants

A Photographic Technique for the Detection of Presumptive Biochemical Mutants

Preliminary Report on the Circumpolar Distribution of Neoechinorhynchus rutili (Acanthocephala) in Fresh Water Fishes

Preliminary Report on the Circumpolar Distribution of <i>Neoechinorhynchus rutili</i> (Acanthocephala) in Fresh Water Fishes

The sulphur metabolism of mould fungi: The use of “biochemical mutant” strains of Aspergillus nidulans in elucidating the biosynthesis of cystine

1. 1. Methods for the isolation of mutant strains with particular biochemical deficiencies are described. 2. 2. “Cystineless” mutants obtained by these techniques have been used in the elucidation of biosynthetic mechanisms. Sulphate appears to be reduced directly to sulphite. It is most probable that sulphite is reduced directly to “sulphoxylate” and does not pass through the metabisulphite-hydrosulphite route. However, it seems that “sulphoxylate” does not combine directly with an organic residue but first dimerized to thiosulphate. The possibility is discussed that cysteine S-sulphonate (serine thiosulphate) may be the next step in the synthesis of cysteine, the most simple hypothesis for cystine synthesis to fit the experimental facts is: ▪ 3. 3. None of the possible breakdown routes of cystine tested appear to be reversible. The possible products of such breakdowns by: a) oxidation of the sulphur atom stepwise to the sulphonic acid; b) reductive deamination followed by a); c) decarboxylation followed by a); appear to yield sulphite in presence of the mould. 4. 4. Cystine can be formed from methionine or homocystine without prior breakdown to sulphite. 5. 5. The conversion of sulphate to sulphite and that of sulphite to thiosulphate appear in each case to be governed by at least two and probably three genes.

MUTATIONS DURING THE GROWTH OF BIOCHEMICAL MUTANTS OF ESCHERICHIA COLI

MUTATIONS DURING THE GROWTH OF BIOCHEMICAL MUTANTS OF ESCHERICHIA COLI

The Consequences of Mutation during the Growth of Biochemical Mutants of Escherichia coli

The Consequences of Mutation during the Growth of Biochemical Mutants of <i>Escherichia coli</i>

Induced Biochemical Mutants of Azotobacter agilis

Induced Biochemical Mutants of <i>Azotobacter agilis</i>

The Germination of Conidia from Biochemical Mutants of Neurospora

The Germination of Conidia from Biochemical Mutants of Neurospora

A Method for Selection of Biochemical Mutants of Neurospora

Numerous investigations in recent-years have firmly established the value of mutants of the mold Neurospora as tools for research in biochemistry and genetics.(1,5,6) Although various means have been used for inducing mutations,(4,5,6) the technique of isolation as described by Beadle and Tatum(4) has been used by most investigators. This method involves isolation of single ascospores, one from each perithecium, derived from a cross of which one parent was treated. By this method at least 97 per cent of the cultures obtained from the single spore isolations are unchanged wild type strains. In order to obtain specific mutants or a diversity of mutants, it is therefore necessary to isolate a very large number of single ascospores.

Biochemical Mutants of Bacterial Viruses

We wish to report some observations on the mutability of phage T4 with respect to cofactor requirements, and on certain features throwing additional light on the mechanism of cofactor action.

Induced Reversions of Biochemical Mutants in Neurospora crassa

American Journal of BotanyVolume 35, Issue 3 p. 150-157 Article INDUCED REVERSIONS OF BIOCHEMICAL MUTANTS IN NEUROSPORA CRASSA Norman H. Giles Jr., Norman H. Giles Jr.Search for more papers by this authorEsther Zimmer Lederberg, Esther Zimmer Lederberg Osborn Botanical Laboratory, Yale University, New Haven, ConnecticutPresent address: Department of Genetics, University of Wisconsin, Madison 6, Wisconsin.Search for more papers by this author Norman H. Giles Jr., Norman H. Giles Jr.Search for more papers by this authorEsther Zimmer Lederberg, Esther Zimmer Lederberg Osborn Botanical Laboratory, Yale University, New Haven, ConnecticutPresent address: Department of Genetics, University of Wisconsin, Madison 6, Wisconsin.Search for more papers by this author First published: 01 March 1948 https://doi.org/10.1002/j.1537-2197.1948.tb05201.xCitations: 28 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume35, Issue3March 1948Pages 150-157 RelatedInformation

Lethal and Sublethal Effects of X-Rays on Escherichia coli as Related to the Yield of Biochemical Mutants

Lethal and Sublethal Effects of X-Rays on <i>Escherichia coli</i> as Related to the Yield of Biochemical Mutants

METHIONINE SYNTHESIS IN NEUROSPORA. THE ISOLATION OF CYSTATHIONINE

Among artificially produced biochemical mutants of Neurospora, those which have lost the ability to synthesize methionine form the largest class. At the present writing 87 occurrences of the methionineless character have been observed in this laboratory following treatment of wild type spores with high frequency radiations (1) or mustard gas (2). Methionineless mutants differ from wild type Neurospora in that they fail to grow on a medium containing only sugar, inorganic salts, and biotin, but do grow if, in addition to these constituents, methionine is supplied. In many of the mutants failure of methionine synthesis results from a block in the reduction of sulfate, which, except for a trace of biotin, is the sole source of sulfur in the basal medium. These strains can utilize reduced forms of inorganic sulfur for growth, as well as methionine and other organic sulfur compounds. On the other hand, some of the mutants require organically bound sulfur for growth, an indication that in these strains the block in methionine synthesis comes at a later stage than sulfate reduction. Similar classes of methionine-requiring mutants have been reported in the mold Ophiostoma by Fries (3) and in Escherichia coli by Lampen et al. (4-6).

A MICROBIOLOGICAL METHOD FOR THE DETERMINATION OF CHOLINE BY USE OF A MUTANT OF NEUROSPORA

Previous communications from this laboratory have described the production of biochemical mutants in the mold Neurospora by means of ultraviolet and x-rays (1, 2). Such mutants are characterized by the inability to carry out specific chemical syntheses which normally occur in the unmutated, or wild type, strain. In each case which has been genetically analyzed the failure of the synthesis has been found to be related to the mutation of a single gene. The strain to be described, known as No. 34486, or cholineless, arose from a culture of wild type Neurospora crassa which had been irradiated with ultraviolet light. It was found to be unable to grow in a medium containing only salts, sugar, and biotin, but it grew normally on the addition of a mixture of water-soluble vitamins. When the components of the mixture were tested singly, it was found that the addition of choline alone permitted normal growth. Up to the present, no completely satisfactory method for the determination of choline in natural products and tissue extracts has been described. Chemical methods, such as precipitation of the reineckate, lack specificity, while the biological method of Fletcher, Best, and Solandt (3) is time-consuming and difficult, and “possesses many dangerous pitfalls for the chemist” (4). The whole subject has been critically reviewed by Best and Lucas (4). It was therefore of interest to determine whether the Neurospora mutant is a suitable test organism in a quantitative assay for choline. The experiments to be described show that this is the case and form the basis of a simple, sensitive, and specific method for the determination of choline in natural products. By this procedure it is possible to determine choline in a concentration of 0.02 mg. per liter; routine analyses can be run on 100 mg. samples of material.