Mutationsversuche an Kulturpflanzen

Summary The genetic behaviour of some X-ray induced early heading mutants of both spring and winter barley was studied. In crosses with original varieties all mutants showed monogenic segregation ratios in F₂-generations. The early heading date of four mutants was found to be due to a dominant allele, while six mutants are dependent on recessive alleles.In crosses of some mutants one with another four different loci for early heading were identified. For them the genetic symbolmat (matura) resp.Mat is proposed.The combination-effect of two non-allelic genes is always additive and manifests itself in a marked transgression. Plants with such genotypes seem to be useless for breeding purposes.

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Mit 2 Abbildungen     

Genetische und physiologische Beziehungen zwischen den Bakteriophagen T1 und D 20

Summary The close relationship between phages T 1 and D 20 was confirmed by genetical crosses. D 20 could be shown to differ from T 1 by at least two genes, both affecting the host range of the phage. The geneDs will render a phage capable of multiplying on the original host of D 20, SF;Ha will enable the phage to lyse B/1. D 20 may thus be formulated as T 1HaDs. Both genes could be localized within the T 1 linkage map, in the vicinity of the geneHr, which is known to control the host range specifity against B/1. The results of genetical, adsorption, and serological studies can be interpreted by the assumption that each gene controls the synthesis of a specific protein, responsible for the adsorption behaviour of the particular phage. A phage will adsorb to SF according to itsDs genotype, to B or its phage resistant mutants according to itsHa genotype. These proteins do not, however, exert their functions independently. Therates of adsorption and neutralization are influenced by the presence or absence of proteins not required for the particular reaction under investigation.

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Mit 4 Textabbildungen     

Genetic mapping and biochemical characterization of mutations in the mannonic hydrolyase structural gene of Escherichia coli K 12

Summary Mutants of E. coli specifically deficient for the enzyme mannonic hydrolyase have been isolated. These strains are unable to metabolize glucuronate but still normally grow on galacturonate; inducibility for the other glucuronate-induced enzymes is not modified.The position of these mutations called uxuA locus in relation to the pyrB-guaC region, and probably near 85.5 minutes, was established by sexual crosses and by P₁ transductionBiochemical characterization of uxuA mutants using thermosensible mutants was achieved by means of thermal inactivation and kinetic studies. Experimental results strongly suggest that uxuA locus is the structural gene of the mannonic hydrolyase.

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Ce mémoire sera inclus dans les travaux présentés par Janine Robert-Baudouy pour l'obtention du grade de «Docteur ès Sciences Physiques» (Université Claude Bernard de Lyon).

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Mémoire présenté par F. Gros     

Genetic mapping and biochemical characterization of mutations affecting altronic hydrolyase structural gene in Escherichia coli K 12

Summary Mutants of E. coli specifically deficient for the enzyme altronic hydrolyase have been isolated. These strains are unable to metabolize galacturonate but still normally grow on glucuronate; inducibility for the other galacturonate-induced enzymes is not modified.The position of these mutations called uxaA locus in relation to the argG, tolC and metC markers was established both by sexual crosses and by P₁ transduction; evidence is presented that uxaA is located between argG and tolC.Biochemical characterization of uxaA mutants using thermosensible revertants or mutants was achieved by means of thermal inactivation and kinetic parameters determination. Experimental results strongly suggest that uxaA locus is the structural gene of the altronic hydrolyase enzyme.

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Ce mémoire sera inclus dans les travaux présentés par Raymond Portalier pour l'obtention du grade de «Docteur ès Sciences» (Université Claude Bernard de Lyon).

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Mémoire présenté par F. Gros     

Genetische Untersuchungen zur Inkompatibilität im Culex-pipiens-Komplex

Zusammenfassung Bei Kreuzungen zwischen Culex pipiens-Populationen verschiedener geographischer Herkunft werden drei Kreuzungstypen festgestellt: normale Kreuzbarkeit, reduzierte Kreuzbarkeit und Inkompatibilität (Nichtkreuzbarkeit). Die drei Kreuzungstypen sind mit Hilfe der Embryonierungsrate, der Schlüpfrate und der entstehenden Nachkommenschaft gegeneinander abgrenzbar. Bei Inkompatibilität sind 99.9% der sich entwickelnden Embryonen letal und etwa 0.1% der Tiere schlüpfen und sind fertile, diploide Weibchen. Die Aktivierung des Eies erfolgt durch das Spermium. Es liegt induzierte, meiotische Parthenogenese vor. Die diploiden, parthenogenetischen Weibchen gehen aus einer Oocyte 2. Ordnung oder aus Teilungsprodukten einer Oocyte 2. Ordnung hervor. Bei den letalen, haploiden Embryonen beteiligt sich das Spermium nicht am Aufbau des Embryos.

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Genetic investigations on the incompatibility in the Culex pipiens complex

Summary In crosses between populations of the mosquito Culex pipiens of different geographical origin three crossing types have been found (1) crosses with normal offspring (2) crosses with reduced offspring and (3) crosses that show almost total incompatibility. In the case of incompatible crosses 99.9% of the developing embryos are lethal and only about 0.1% of the embryos hatch and develop into fertile diploid females. The origin of the exceptional diploid females has been investigated by means of the marker genes Kuf, r, w, var, y and ru. These females develop from a diploid oocyte or from a diploid nucleus that originated by fusion of the pronucleus and the last polar body. This has been concluded from the frequency of homozygous and heterozygous offspring from heterozygous females, the frequency of equational separation of different genes and the distribution of cross-over gametes in the exceptional females. Based on the genetical data it is argued that induced meiotic parthenogenesis takes place. The sperm does not play any part in the production of the diploid females and the lethal embryos. After the activation of the egg the sperm moves to the center of the egg but it does not succeed to fuse with the pronucleus. As a result the pronucleus starts to develop into a haploid embryo in about 99.9% and only in a few cases is the diploidy restored by a change in the meiotic process in the egg.

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Teil einer Dissertation der Math.-Nat. Fakultät der Universität Mainz

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Danksagung: Herrn Prof. Dr. H. Laven danke ich für die Bereitstellung des Untersuchungsmaterials sowie für die Anregungen bei der Durchführung der Arbeit.

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Angenommen durch H. Stubbe     

Crossing analysis of sorbose resistant mutants of Neurospora crassa

Summary After treatment of the conidia of Neurospora crassa with nitrous acid 19 of the resulting mutants were selected for their resistance to sorbose, an agent which has a toxic effect on the wild type. The selected sorbose resistant mutants were analyzed genetically by crossing them with tester strains containing known markers. Mutational sites were thus found to be located on at least 5 of the full complement of 7 linkage groups. 9 sites were found to be located on the left arm of linkage group VI near the ylo-marker. These were so far not separable by recombinational analysis and therefore seem to represent a single gene-locus (A). Other sorbose resistant sites were mapped on linkage groups I, III (gene C), V and VII (gene B). Another site which has not yet been definitely located is not closely linked to any of the aforementioned. One site each on linkage groups I and VI were mapped more precisely by means of 3-point crosses. These crosses permitted the location of these sites of sorbose resistance in regard to neighbouring markers. From these crosses it is concluded that the mutation of any 1 of at least 6 different chromosomal genes can cause the formation of a sorbose resistant phenotype. The mutation of any 1 of 4 of these genes could result in a mutant with an altered sorbose permease system or containing a suppressor which decreases the efficiency of the permease system.

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I. Teil einer Habilitationsschrift bei der Naturwissenschaftlichen Fakultät der Universität München.     

Elektronenmikroskopische Untersuchungen zur Genese des Golgi-Apparates (Dictyosomen) und ihrer Kernabhängigkeit beiAcetabularia

Summary The genesis of dictyosomes has been studied on nucleate and enucleateAcetabularia cells.Dictyosomes differentiatede novo from prestages, the perinuclear bodies, which are synthesized under the actions of nuclear ribonucleoprotein. Consequently the formation of dictyosomes is nucleus (DNA) dependent.This was shown by experiments using actinomycin and puromycin and by experiments on darkened and enucleate cells.There is a relationship between dictyosome structure and function and the morphogenetic activities of a cell.

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Mit 10 Textabbildungen     

VerÄnderte Anordnung der Cysten beiAcetabularia mediterranean

Zusammenfassung Die Cysten vonAcetabularia mediterranea sind in den Hüten normalerweise radiÄrsymmetrisch angeordnet. In einigen Zellen unseres Standard-Kulturmaterials fanden sich jedoch Hüte mit bilateralsymmetrischer Cystenanordnung. Die Nachkommenschaft dieser Zellen (bisher zwei Folgegenerationen) zeigt das gleiche morphologische Merkmal. Das beschriebene Merkmal könnte daher auf einer genetischen VerÄnderung beruhen. Dies würde die erste erfolgreiche Isolierung und Kultur einer Mutante beiAcetabularia bedeuten.

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Changed arrangement of cysts inAcetabularia mediterranea

Summary Cysts ofAcetabularia mediterranea are normally arranged within the cap in a radial symmetric manner. In one population of our standard laboratory material, however, some cells were found with cysts arranged in a bilateral symmetric manner. The progeny of these cells (two following generations, so far) shows the same morphological characteristic, indicating that the different arrangement of cysts might be the result of genetical differences. This would mean the first successful isolation and cultivation of a mutant ofAcetabularia.

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Herrn Prof. J.HÄmmerling zur Vollendung seines 75. Lebensjahres gewidmet.     

Localization of a non-Mendelian gene in Chlamydomonas reinhardii

Summary Transfer of a non-Mendelian neamine-dependent (nd) mutant to an antibioticfree medium results in neamine-sensitive and neamine-resistent revertants. These reversions are caused by extranuclear mutations.The neamine-sensitive revertants are no more able to split offnd-cells after back-donation to neamine containing medium. Therefore they are different from the streptomycin-sensitive revertants of a streptomycin-dependent (sd) mutant. These mutants were capable ofsd-segregation though their potence ofsd-segregation diminished on antibiotic-free medium with increasing time of cultivation.The different behaviour can be explained by the fact that manysd-genes are present which have to be appointed to the mitochondria. On the other side, thend-gene exists only in few copies and is located therefore in the chloroplast.Several experiments with differing methods are discussed to localize the extranuclear genes.

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Vorgelegt durch G. Melchers     

Deletion of the mating-type sequences in Podospora anserina abolishes mating without affecting vegetative functions and sexual differentiation

The mating-type locus of Podospora anserina controls fusion of sexual cells as well as subsequent stages of development of the fruiting bodies. The two alleles at the locus are defined by specific DNA regions comprising 3.8 kb for mat+ and 4.7 kb for mat–, which have identical flanking sequences. Here we present the characterization of several mutants that have lost mat+-specific sequences. One mutant was obtained fortuitously and the other two were constructed by gene replacement. The mutants are deficient in mating with strains of either mat genotype but are still able to differentiate sexual reproductive structures. The loss of the mating type does not lead to any discernible phenotype during vegetative growth: in particular it does not change the life span of the strain. The mutants can recover mating ability if they are transformed with DNA containing the complete mat+ or mat– information. The transformants behave in crosses as do the reference mat+ or mat– strains, thus indicating that the transgenic mat+ and mat– are fully functional even when they have integrated at ectopic sites.     

Characterization of two temperature-sensitive mutants of Sigma virus (authors transl)

Summary Temperature-sensitive mutants have been isolated from Drosophila Sigma virus, a Rhabdovirus inducing CO₂ sensitivity in Drosophila melanogaster. We have studied the decay of infectious centers at non permissive temperature. The proportion of destroyed infectious centers is the same for the wild type, ts⁺, and for ts9. On the opposite, it is more important for ts 4. Temperature-sensitive function of ts 4 appears necessary to the viral genome replication. With the three clones, ts⁺, ts 4 and ts 9, we have obtained stabilized Drosophila females able to transmit Sigma virus to their whole progeny. We have tried to see in each case, if stabilized flies could transmit the virus to their progeny at non permissive temperature. Flies stabilized with ts⁺ and ts 9 can, flies stabilized with ts 4 cannot. Therefore two categories of mutants are defined: those that are transmitted hereditarily. at non permissive temperature, and not blocked in genome replication. Those that are blocked in genome replication and not transmitted. When the virus cannot replicate, the divisions in the germ line cells dilute the viral genomes. The consequence will be a real healing of germ line cells, and then a break in hereditary transmission by stabilized flies. All the results with temperature-sensitive mutants are coherent with this hypothesis.

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Étude de mutants thermosensibles du virus Sigma

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Mémoire présenté par F. Gros     

A search for chromatid interference in the male house mouse

Summary Mouse spermatocyte chiasma frequency observations by Slizynski shew chiasma interference which can be adequately represented by a model due to Mather. Some genetical implications of this model are analysed, assuming various strengths of chromatid interference, and are compared with genetical observations. This indicates that there is little or no chromatid interference in the male mouse, A new map length and recombination frequency conversion table is given, based an the observed chiasma frequencies.

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Zusammenfassung Beobachtungen von Slizynski über Chiasma-Häufigkeit in Maus-Spermatocyten konnten befriedigend ausgedeutet werden auf Grund von Mathers Modell der Chiasma-Interferenz. Die genetischen Folgerungen aus diesem Modell wurden weiterhin untersucht unter Annahme verschiedener Grade von Chromatid-Interferenz. Ein Vergleich mit den genetischen Daten zeigt, daß Chromatid-Interferenz in der Maus gering oder abwesend ist. Unter Zugrundelegung der beobachteten Chiasma-Häufigkeiten wird eine neue Tabelle zur Umwandlung von Rekombinationsdaten in Abständen auf den Chromosomenkarten gegeben.

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With 6 figures in the text.

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Member of the Medical Research Council's scientific staff.     

The use of protoplast fusion in demonstrating chromosomal and mitochondrial inheritance of respiratory-deficiency in Kluyveromyces lactis, a petite-negative yeast

Summary Protoplast fusion has provided us with a means of genetical analysis in respiratory-deficient mutants of the petite-negative yeast, Kluyveromyces lactis. Demonstration of mitochondrial-inheritance in respiratory-deficient mutants of petite-negative yeasts has not previously been possible due to the inviability of petite/microcolony cells.     

Tagging of genes involved in multidrug resistance in Aspergillus nidulans

We have used a plasmid containing the Neurospora crassa pyr4 gene to transform an Aspergillus nidulans pyrG89 mutant strain in the presence of BamHI, and isolated multidrug-sensitive mutants among the transformants. Using this approach, we hoped to identify genes whose products are important for drug resistance by analyzing gene disruptions that alter the drug sensitivity of the cell. About 1300 transformants isolated following transformation were screened for sensitivity to drugs or various stress agents with different and/or the same mechanism of action. Seventy-seven of these transformants showed sensitivity to at least one drug, while fourteen transformants showed a complex phenotype of sensitivity to different drugs. The pyr4 marker was shown to be tightly linked to the mutant phenotype in only 36% of the pleiotropic mutants analyzed in sexual crosses. Genetic crosses between our multidrug-sensitive transformants and cycloheximide-sensitive and imazalil-resistant mutants of A nidulans were performed to determine whether mutations were present at the same loci. We have shown that the gene imaD that confers resistance to imazalil may also be involved in cycloheximide and hygromycin sensitivity, since this mutation is allelic to scyB (mutant scy290). In addition, the cross between the transformant R223 and the imazalil-resistant mutant ima535 showed that both mutations are in the same complementation group, suggesting that the gene imaG could also be involved in cycloheximide and itraconazole sensitivity. Received: 30 August 1999 / Accepted: 22 February 2000     

Zur Natur Der Ausgedehnten Mutationen Des Coliphagen T4

Summary No recombination could be observedwithin three extended mutations (block mutations) of the rII region of phage T4. The block mutations are studied under two different conditions, where (1) both parental particles contained an identical block mutation, and where (2) a block mutation was present in only one parent, while the other contained a point mutation, or was wild type at the corresponding location.In further experiments it was shown that the presence of a block mutation in only one parent reduces recombinationoutside the block. This interference decreases with increasing distance between the block mutation and the other sides.Although up to now no difference in density could be observed between wild type particles and block mutants, the genetic data which are reported here do support the interpretation that block mutations represent deletions within the genetic material.

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Mit 3 Textabbildungen

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Dissertation an der Mathematisch-Naturwissenschaftlichen Fakultät der Universität zu Köln, eingereicht im Januar 1962.     

Genetic diversity and heterosis in nicotiana

Summary Two flue-cured varieties of N. tabacum were crossed to putative progenitor species and to distantly related species. Heterosis for yield, plant height, and number of leaves was largest for crosses to progenitor species, particularly to N. otophora and N. tomentosiformis. The magnitude of this heterosis appeared to be greater than estimates presented in the literature for crosses among varieties of N. tabacum. An additional study presented some evidence for the genomic basis of heterosis in crosses of N. tabacum with N. tomentosiformis and N. sylvestris.

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Zusammenfassung Zwei für R?hrentrocknung geeignete Sorten von N. tabacum wurden mit vermutlichen Ausgangs- und mit entfernt verwandten Arten gekreuzt. Die Heterosis für Ertrag, Pflanzenh?he und Blattanzahl war am st?rksten bei Kreuzungen mit den Ausgangsarten, besonders mit N. otophora und N. tomentosiformis. Das Ausma? dieser Heterosis schien die in der Literatur berichteten Sch?tzungen für Kreuzungen zwischen Sorten von N. tabacum zu übertreffen. Eine weitere Untersuchung erbrachte Hinweise für die genomatische Grundlage der Heterosis bei Kreuzungen von N. tabacum mit N. tomentosiformis und N. sylvestris.

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Dedicated to Dr. George F. Sprague on the occasion of his 65^th birthday.

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Paper Number 2318 of the Journal Series of the North Carolina Agricultural Experiment Station. This investigation was supported in part by Public Health Service Research Grant GM 11546 from the Division of General Medical Sciences.     

Nuclear inheritance of resistance to antimycin A in Saccharomyces cerevisiae.

Summary A group of 30 independent mutants of Saccharomyces cerevisiae, resistant to the respiratory inhibitor antimycin A, was investigated from a genetical and biochemical point of view. All the mutants can be grouped into two nuclear loci: AMY1 maps on the VII chromosome, between leu 1 and trp 5; AMY2 is close to its centromere on either chromosome XVIII or XIX. Both genes do not affect mitochondrial structures or functions.     

Deficiency of double mutant recombinants in crosses of phage T4

Summary Only 1.4% of the double mutant recombinants expected on the basis of wild-type recombination frequencies were observed in the combined data from two-factor crosses between a gene 37 amber mutant, amB280, and eighteen different temperature sensitive mutants which were also defective in gene 37. Similar, though less extreme, deficiencies of double mutant recombinants were observed by Doermann and Parma (1968) for mutants in several other genes. In our amB280xts crosses, frequencies of wild-type recombinants were in reasonably good agreement with those expected from the map positions of the mutants determined in crosses not involving amB280. Wild-type and double mutant recombinants were found at comparable frequencies when each of three other gene 37 amber mutants was crossed to a gene 37 temperature sensitive mutant.Experiments were performed to test whether the deficiency of double mutant recombinants in the amB280xts crosses could be explained by assuming that they occurred primarily in heterozygous particles, where their expression was masked. However, no evidence in support of this explanation was found. Other possible explanations, that the deficiency of double mutants was due to their inviability or the inability of double mutant chromosomes to replicate, were also inconsistent with our observations. The hypothesis considered to most plausibly explain our evidence is that the process by which double mutant recombinant chromosomes are formed is inhibited in the vicinity of a poorly suppressed am mutation.     

New tools for mitochondrial genetics of Chlamydomonas reinhardtii: manganese mutagenesis and cytoduction

Summary A novel and efficient genetic procedure is described for generating mitochondrial mutants of the green alga Chlamydomonas reinhardtii. The development of a mutagenesis procedure using manganese cations and the application of cytoduction techniques resulted in a combined approach for the generation and analysis of mitochondrial mutants. Although mitochondrial mutations are inherited in sexual crosses from the minus mating type parent, the cytoduction technique can be used to transfer mitochondrial mutations into recipient strains with different genetic backgrounds, irrespective of their mating type. Cytoduction allows the transfer of mitochondrial markers from diploid to haploid cells also, which is of great benefit since diploid cells do not germinate in C. reinhardtii. We report here the isolation and characterisation of eight mutants, which are resistant to the antibiotics myxothiazol and mucidin. The mutants all have point mutations in the mitochondrial gene for apocytochrome b. Using in vitro-amplified cytb gene fragments as probes for direct DNA sequencing, three different types of single base pair substitutions were revealed in all mutants tested. In particular, amino acid substitutions in the mutant apocytochrome b polypeptide have been identified at residues 129, 132 and 137, which have been implicated in forming part of an antibiotic-binding niche. The amino acid substitution at position 132 has not been so far described for mutant apocytochrome b in any other organism, prokaryotic or eukaryotic. The genetic approach presented here confirms C. reinhardtii as a model system that is unique among plant cells.