Showing papers by "University of Hohenheim published in 1974"
42 citations
TL;DR: Summary 4400 anthers of two pure lines of Petunia hybrida and of the hybrid between them cultivated in vitro produced 1 haploid and 31 diploid or triploid plants.
28 citations
TL;DR: Pistils were isolated from flowers of a clone of Mimulus luteus and pollen of Torenia fournieri was placed directly onto the ovules and in 1% of the carpels treated in this way a haploid parthenogenesis was induced.
24 citations
TL;DR: The reisolation of the episomal DNA in the petunia experiments excludes any intensive bacterial degradation and reutilization of the labelled exogenous DNA respectively DNA building units.
22 citations
TL;DR: The replication of the bacterial plasmids is dependent on two chromosome-determined products (dnaA and dnaC), which are involved in the initiation of the chromosomal DNA synthesis of Escherichia coli.
Abstract: The replication of the bacterial plasmids is dependent on two chromosome-determined products (dnaA and dnaC), which are involved in the initiation of the chromosomal DNA synthesis of Escherichia coli. The inhibition of Col E1 DNA synthesis in a dnaA-mutant (CRT 46) at the restrictive temperature, is eliminated by the addition of low doses of chloramphenicol (3 μg/ml). Under these conditions, a stimulated and relaxed synthesis of this plasmid is observed. The ability of chloramphenicol to overcome the inhibition of Col E1 DNA synthesis is dependent on the extent of the residual plasmid DNA synthesis at the time of addition of the antibiotic. Col E1 DNA synthesized at 43 °C in the presence of chloramphenicol, largely consists of supercoiled DNA circles containing RNA segments as revealed by their sensitivity to ribonuclease H of Escherichia coli and alkali. Addition of rifampicin to chloramphenicol-treated cells causes first a slight inhibition of the relaxed Col E1 DNA synthesis at 43 °C and then a further stimulation.
An immediate increase in plasmid DNA synthesis after the addition of rifampicin to chlor-amphenicol-treated cells at 43 °C is observed in the dnaA-mutant carrying the antibiotic resistance factor R1. Another transmissible plasmid (Hly PM152) does not show this stimulated DNA synthesis. Stimulation of Col E1 and R1 DNA synthesis by rifampicin does not occur in chlor-amphenicol-treated cells of the dnaA-mutant with a rifampicin-resistant RNA polymerase. Chloramphenicol and/or rifampicin cannot eliminate the inhibition of plasmid replication at the restrictive temperature in a dnaC mutant (PC 2). In the presence of chloramphenicol, however, more complex Col E1 DNA molecules (dimeric and trimeric DNA forms) are synthesized at the restrictive temperature in the dnaC-mutant.
22 citations
TL;DR: Coiling of intact or excised cucumber (Cucumis sativus) tendrils can be induced by IAA or ethylene, and the velocity of coiling in different regions of the tendrils correlates with the capacity for auxin-stimulated ethylene synthesis.
Abstract: Coiling of intact or excised cucumber (Cucumis sativus) tendrils can be induced by IAA or ethylene. The velocity of coiling in different regions of the tendrils correlates with the capacity for auxin-stimulated ethylene synthesis. Ethylene (Ethephon) induces an increase in membrane permeability of tendrils, and as a result the efflux of substances previously taken up (glucose) is stimulated. It is assumed that this may contribute to the contraction of the ventral side of the tendril. The excretion of glucose after ethylene treatment can be reduced by Ca2+, and calcium also inhibits coiling of tendrils following incubation in ethephon solution. Auxin stimulated ethylene synthesis in the ventral half of the tendril is several times higher than in the dorsal half and it is hypothesized that this may be a cause for the different reactions of the two sides of a tendril following a mechanical stimulus.
21 citations
TL;DR: Nuclei were prepared from isolated mesophyll protoplasts of the following species by treatment with Triton X 100 and the amphidiploid hybrid between the two tobacco species and the product synthetizised during the incubation period could be identified as RNA.
17 citations
TL;DR: Mechelke et al. as mentioned in this paper developed a new functional chromosome model, which considers not only the chromomeres but also the interchromomeres as independent genes, and defined the genes involved in the basic synthesis as the "basic genome".
Abstract: In a preliminary report a new functional chromosome model is developed. Contrary to all present hypotheses this model considers not only the chromomeres but also the interchromomeres as independent genes. It is assumed that the interchromomeres are obligatory miniature-puffs, which are formed by the genes of "basic synthesis" (the synthesis which guarantees the fundamental cellular life). The genes involved in the basic synthesis are collectively defined as the "basic genome". The chromomeres developed during evolution through saltatory replication from the basic genes and contain the loci of the stage- and tissue-specific differential gene activity. All the genes of the differential synthesis are designated as the "differential genome".ZUSAMMENFASSUNG: In einer vorlaufigen Mitteilung wird ein neues funktionelles Chromosomenmodell entwickelt, das entgegen allen bisherigen Hypothesen sowohl Chromomeren als auch Interchromomeren als eigenstandige Gene betrachtet. Es wird angenommen, das die Interchromomeren obligatorische Miniatur-Puffs sind, die von den Genen der jeder Zelle gleichermasen eigenen "Basissynthese" gebildet werden. Die Summe der Gene, die an der Basissynthese beteiligt sind, wird als "Basisgenom" definiert. Die Chromomeren haben sich wahrend der Evolution durch saltatorische Replikation aus Basisgenen entwickelt und enthalten die Loci der Stadien- und gewebespezifischen differentiellen Genaktivitat. Ihre Gesamtheit wird als "Differentialgenom" definiert.Fur die Anregung zu dieser Arbeit gilt Herrn Prof. Dr. F. Mechelke mein besonderer Dank.
15 citations
TL;DR: Most of the acid-insoluble radioactivity produced by incubation of rat liver nuclei with [14C]NAD is rendered soluble by treatment with cold neutral hydroxylamine, with the greatest activity being found in the adenosine diphosphoribose fraction.
14 citations
TL;DR: The author reviews plants of saline habitats, characterized by soil types, including general aspects of development, development, production, photosynthesis, respiration, water relations, salt relations inside plants, metabolism, stress, resistance and tolerance.
Abstract: The author reviews plants of saline habitats , characterized by soil types. The effects of saline condit ions on plants are described, main ly on a physiological basis, including general aspects, development ( termination, growth, morphology), production, photosynthesis, respiration, water relations, salt relations inside plants, metabolism, stress, resistance and tolerance. Wi th respect to the ecological unders tand ing of the influence of salt, external (osmotic) effects have to be dist inguished from in terna l effects which involve enzymes. Ecological tolerance should be seen as the chance of the survival of individuals. This means tha t separate determinat ions mus t be made of the resistance of organs tissues, ma in ly meristerns.
11 citations
TL;DR: Dye-buoyant-density separation and titration with ethidium bromide indicate that this ring-open mitochondrial DNA contains “covalently closed” circular DNA molecules which are free of superhelical turns.
Abstract: The non-intercalating tryptanocidal drug berenil inhibits completely the synthesis of the mitochondrial DNA in cultured human cells. This interference appears to be fairly selective, as the effect on the synthesis of the nuclear DNA is relatively small.
The exposure of the cells to the drug results in a conversion in vivo of existing supercoiled mitochondrial DNA into DNA molecules with the hydrodynamic properties of ring-open mitochondrial DNA. Dye-buoyant-density separation and titration with ethidium bromide indicate that this ring-open mitochondrial DNA contains “covalently closed” circular DNA molecules which are free of superhelical turns.
TL;DR: In this paper, Protoplasts were isolated from mesophyll tissue of cotyledons and regenerated cell walls and divisions were observed, and callus obtained from protoplasts was induced to differentiate roots.
TL;DR: Incubation of the colicinogenic Escherichia coli strain JC 411 (ColE1) at elevated temperatures leads to the accumulation of catenated molecules and replicative intermediates of this plasmid, which is more thermosensitive than chromosomal DNA replication in P. mirabilis.
Abstract: Incubation of the colicinogenic Escherichia coli strain JC 411 (ColE1) at elevated temperatures (47–49°) leads to the accumulation of catenated molecules and replicative intermediates of this plasmid. Mature supercoiled ColE1 DNA molecules synthesized under these conditions have an increased number of tertiary turns as shown by electron microscopy. The monomeric tightly supercoiled molecules possess a slightly slower sedimentation rate and a higher binding capacity for ethidium bromide than supercoiled monomers synthesized at lower temperatures. Recombination deficient mutants of E. coli recA, recB and recC, which carry the ColE1 plasmid, form about the same amount of catenated molecules at the elevated temperature as a rec+ strain. In addition, we have observed by electron microscopy a small percentage (∼5% of the circular DNA molecules) of minicircular DNA molecules in all preparations of JC 411 (ColE1). They are homogenous in size, with a molecular weight of 1.4x106 daltons. Addition of chloramphenicol to a culture of Proteus mirabilis (ColE1) leads to an increased amount of higher multiple circular oligomers and to a stimulated accumulation of catenated ColE1 DNA molecules of varying sizes. ColE1 DNA synthesis is more thermosensitive than chromosomal DNA replication in P. mirabilis. Plasmid replication stops completely at temperatures above 43°C.
TL;DR: In this communication, it is shown that the regulation of colicin El production primarily takes place on the transcriptional level, with a possible additional regulation occurring at translation of the colic in specific mRNA that seems to be cAMP/crp dependent.
TL;DR: The Wirkung zweier Chalkone auf Anthocyansynthese in isolierten Petalen von Petunia hybrida wurde untersucht as mentioned in this paper.
TL;DR: In this article, it was shown that the incorporation of [1- 14 C]acetate into cyanidin 3-monoglucoside in Petunia hybrida could not be specifically prevented by adding either transcriptive or translational antimetabolites.
TL;DR: The accumulation of D-loop mitochondrial DNA molecules in mouse cells is due to abortive replication events, and Pulse-chase-pulse experiments indicate that the different allomorphic forms of the mitochondrial DNA turn over at a different rate.
Abstract: Mouse mitochondrial DNA can be fractionated by means of band sedimentation into the allomorphic forms supercoiled circle (34 S), open circle (24 S) and linear rod (21 S). The separation of the ring-open form based on its hydrodynamic properties is not necessarily an indication of the chemical properties of this form, i.e. a nick in the phosphodiester backbone of at least one strand of the duplex DNA. Circular duplex DNA molecules may show an ambiguous behaviour. During sedimentation the high frictional coefficient of open circles is observed. However, as judged by other criteria the molecules behave like covalently closed circular DNA with invariant topological winding (restricted uptake of an intercalating dye).
A large part of mouse mitochondrial DNA occurs as D-loop mitochondrial DNA molecules which contain a displaced single-stranded region in the duplex DNA molecule. The insertion of the new displacing strand reduces the rotation of the parental strands around each other and therefore reduces the number of right-handed superhelical turns in the “covalently closed” circular DNA. For this reason, the bulk of the mouse D-loop mitochondrial DNA molecules display a sedimentation behaviour (28 S) similar to that of ring-open (nicked) molecules although these molecules contain a “covalently closed” phosphodiester backbone in each strand. Pulse-chase-pulse experiments, labeling firstly with [2-14C]thymidine and secondly with [Me-3H]thymidine, indicate that the different allomorphic forms of the mitochondrial DNA turn over at a different rate. The lowest turnover rate is observed in alkali-stable supercoiled mitochondrial DNA and in D-loop mitochondrial DNA. It is concluded that the accumulation of D-loop mitochondrial DNA molecules in mouse cells is due to abortive replication events.
TL;DR: The amount of transpiration of leaves was correlated to the different formation of the wax layer, and thick and felt-like structure of the Wax layer above the stomatas reduces the water loss considerably.
Abstract: The wax structure of plant leaves has been investigated by scanning electron microscopy and with the replica technique by transmission electron microscopy In addition to replicas of the wax layer, replicas of the leaf surface after removal of the wax have been examinedThe wax layer is very thick and felt-like, especially when the plants have been grown at low humidity In this case the stomatas are also smaller than those of plants grown at high humidityThe amount of transpiration of leaves was correlated to the different formation of the wax layer Thick and felt-like structure of the wax above the stomatas reduces the water loss considerably On the other hand all water evaporates from leaves in a short time after removal of the wax
TL;DR: In this article, the authors show that the 0.0-Diradikal (2 ) nur als Zwischenstufe erw artet werden kann, wenn dessen drei C-Atome eine koplanare Anordnung erreichen.
Abstract: HMO Berechnungen zeigen, daß dieses 0.0-Diradikal (2 ) nur als Zwischenstufe erw artet werden kann, wenn dessen drei C-Atome eine koplanare Anordnung erreichen4. Für n = 1,2,3 ist dies nicht der Fall, wie aus Modellen hervorgeht3a-7, dagegen jedoch für n = 4.Exo-4-Methyl-2.3-diazabicyclo[4.3.0]nona-2.8-dien (3) sollte sich, wenn eine Zwi schenstufe ähnlich 2 vorliegt, von den Systemen m it n = 1,2,3 unterscheiden und ein Verhalten wie das monocyclische t rans 3.5 Di m ethyl -1 -pyrazolin (4) zeigen. 3 entsteht durch 1.3-dipolare Cycloaddition von D iazoäthan an Cyclohexadien-1.3 (8 h, R aum tem pe ra tu r, 60% ); 1H-NMR(CC14) : d = 1,20 (d, 3H), 0,9-2,1 (m, 5H), 4,50 (m, 2H), 6,10 (m, 2H) ppm, die vicinale K opplungskonstante des H an C-4 zum Brückenkopfproton ist J = 2,8 H z8. IR (Film): -(N H ), 1540 cm-1 (N =N ). UV (?i-Hexan): Amaxfe) = 332 nm (350). MS(11 eV): m/e = 136 (18%, M+), 108 (M+-Na). 3 liefert als Reaktionsprodukte der Thermolyse und Photolyse exo-(5) und endo-7-Methylbicyclo[4.1.0]hept-2-en (6 ) (Gl. (2))6. Bei Ersatz der Methylgruppe an C-4 in 3 durch Deuterium en tsteh t 2.3-Diazabicyclo[4.3.0]nona2.8-dien-4.4-d2, dessen milde Thermolyse ausschließ lich Bicyclo[4.1.0]hept-2-en-7.7-d2 ergibt, wobei
TL;DR: In cell suspensions of bacteria grown with 5-amino-4-chloro-2-phenyl-3 (2H)-pyridazinone (pyrazon) as sole source of carbon o- methyl-pvrazon and m-methyl- pyrazon were converted to the cor responding hydroxymethyl compounds.
Abstract: In cell suspensions of bacteria grown with 5-amino-4-chloro-2-phenyl-3 (2H)-pyridazinone (pyrazon) as sole source of carbon o-methyl-pvrazon and m-methyl-pyrazon were converted to the cor responding hydroxymethyl compounds. p-Methyl-pyrazon was not metabolized.
TL;DR: In this article, the wax structure of plant leaves has been investigated by scanning electron microscopy and with the replica technique by transmission electron microscope, and replicas of the leaf surface after removal of the wax have been examined.
Abstract: The wax structure of plant leaves has been investigated by scanning electron microscopy and with the replica technique by transmission electron microscopy. In addition to replicas of the wax layer, replicas of the leaf surface after removal of the wax have been examined. The wax layer is very thick and felt-like, especially when the plants have been grown at low humidity. In this case the stomatas are also smaller than those of plants grown at high humidity. The amount of transpiration of leaves was correlated to the different formation of the wax layer. Thick and felt-like structure of the wax above the stomatas reduces the water loss considerably. On the other hand all water evaporates from leaves in a short time after removal of the wax.
TL;DR: The existence of glucosidiced 3,4,2′,4′,6′-penta-hydroxy-chalcone in the biosynthetic pathway of flavonoids in petals of Petunia hybrida at the stage of intensive and linear anthocyanin accumulation is ascertained.
TL;DR: Threonine deaminase from a mutant of Escherichia coli growing alternatively with isoleucine or pyridoxine is a dimer, whereas the wild-type enzyme is a tetramer.
Abstract: Threonine deaminase from a mutant of Escherichia coli growing alternatively with isoleucine or pyridoxine is a dimer, whereas the wild-type enzyme is a tetramer.
TL;DR: Inkubation mit Abscisinsäure verursacht bei Mesophyll-Protoplasten von Petunia hybrida einen Anstieg der Photosyntheserate.
Abstract: Inkubation mit Abscisinsaure verursacht bei Mesophyll-Protoplasten vonPetunia hybrida einen Anstieg der Photosyntheserate.
TL;DR: In this article, a new dam line to be mated by a terminal sire line (C-line) for fat lamb production in commercial crossbreeding is developed by crossing a local breed (Merinolandschaf, A-line), and an exotic breed (Finnish Landrace, B-line).
01 Jul 1974
TL;DR: In this paper, the authors made a comment on the publication ofSchwenke (1974) in which phytomedicine is mentioned as to be a threat to entomology.
Abstract: Entomology and Phytomedicine
This article represents a comment on the publication ofSchwenke (1974) in which phytomedicine is mentioned as to be a threat to entomology. With regard to this it should be stated that entomology and phytomedicine are independent fields of knowledge. The insect is standing in the centre of entomology, whereas phytomedicine is centred on the protection of plants from diseases and injuries. The relation of entomology to phytomedicine results from the fact that numerous insects belong to the most important organisms causing damage to plants. Specialized entomogists are qualified, within phytomedicine, mainly for such tasks as research and teaching. The practical plant doctor, however, who may be engaged in extension work, needs a broad phytomedical education; in so far entomology cannot occupy a special position within phytomedicine. From the standpoint of phytomedicine entomology, as a part of zoology, is a basic discipline similar to mycology, virology, etc. Entomology, therefore, is needed by phytomedicine, not threatened. Apart from this there are, of course, fields of activity in entomology which are outside of phytomedicine.