Showing papers by "University of Tübingen published in 1987"

A new petunia flower colour generated by transformation of a mutant with a maize gene

Abstract: Petunia hybrida is one of the classical subjects of investigation in plants in which the pathway of anthocyanin biosynthesis has been analysed genetically and biochemically. In petunia cyanidin- and delphinidin-derivatives, but no pelargonidin-derivatives are produced as pigments. This is due to the substrate specificity of the dihydroflavonol 4-reductase of petunia, which cannot reduce dihydrokaempferol. The petunia mutant RL01, which accumulates dihydrokaempferol, shows no flower pigmentation. RL01 served as a recipient for the transfer of the A1 gene of Zea mays encoding dihydroquercetin 4-reductase, which can reduce dihydrokaempferol and thereby provided the intermediate for pelargonidin biosynthesis. Transformation of RL01 with a vector p35A1, containing the A1-complementary DNA behind the 35S promotor leads to red flowers of the pelargonidin-type. Thus a new flower pigmentation pathway has been established in these plants.

Significance of tubulointerstitial changes in the renal cortex for the excretory function and concentration ability of the kidney: a morphometric contribution.

Abstract: This is an editorial review of investigations into the correlation of structure and function of the kidney in various inflammatory and noninflammatory glomerular diseases and in focal and diffuse interstitial nephritis. In detail these investigations produced the following results: (1) The excretory function of the glomeruli for substances usually eliminated with the urine is, in the case of inflammatory and noninflammatory glomerular diseases, detrimentally affected by tubulointerstitial changes, i.e. by processes accompanied by interstitial fibrosis and tubular atrophy. Likewise primary interstitial renal diseases when accompanied by interstitial fibrosis and tubular atrophy may lead to reduction in GFR. (2) Inflammatory and noninflammatory glomerular diseases, even when very severe, are not accompanied by a measurable reduction in GFR when the renal cortex interstitium shows no changes and the tubules exhibit no pathological findings. (3) The concentration ability of the kidney, too, depends primarily on tubulointerstitial changes and not primarily on a reduction of the glomerular filtration surface area. As interstitial fibrosis and tubular atrophy increase, the maximum concentration ability of the kidney decreases, even when the glomerular structure is preserved. (4) The decrease in GFR in the case of processes in the renal cortex accompanied by severe interstitial fibrosis is the result of the reduction of the number and of the area of the postglomerular vessels, i.e. the result of an impeded outflow from the glomeruli and of a concomitant slower circulation through the glomeruli. (5) In the case of inflammatory and noninflammatory glomerular and extraglomerular renal diseases accompanied by slight interstitial fibrosis and tubular atrophy, the GFR is detrimentally affected via a hormonally controlled self-regulating mechanism (Thurau-mechanism) in the form as modified by Baumbach and Skott and Leyssac. The glomerular function thereby adapts to an insufficient tubular function, without there necessarily being any structural changes in the glomeruli.

Selection procedure for deregulated iron transport mutants (fur) in Escherichia coli K 12: fur not only affects iron metabolism

Abstract: A selection procedure using Mn2+ is described. A high percentage of the Mn2+ resistant mutants had constitutive iron transport systems. By P1 transduction, and complementation with the cloned fur gene it could be shown that nearly all the mutants constitutive in the expression of the operon fusion fiu::lambda placMu were only defective in fur. High concentrations of manganese inhibited the derepression of an iron-regulated lac operon fusion. In another iron-regulated lac operon fusion that was inducible by iron, manganese also induced the production of beta-galactosidase. Most of the fur mutants isolated (80%) were not able to grow on succinate, fumarate or acetate. After transformation with a fur+ plasmid all 39 mutants tested were able to grow on succinate. In fur mutants the presence of succinate in the growth medium reduced succinate uptake rates by 50%-70%. Succinate dehydrogenase activity was reduced to 10% of that of the parent strain.

Resolvent Positive Operators

Abstract: Resolvent positive operators on an ordered Banach space (with generating and normal positive cone) are by definition linear (possibly unbounded) operators whose resolvent exists and is positive on a right half-line. Even though these operators are defined by a simple (purely algebraic) condition, analogues of the basic results of the theory of Q-semigroups can be proved for them. In fact, if A is resolvent positive and has a dense domain, then the Cauchy problem associated with A has a unique solution for every initial value in the domain of A, and the solution is positive if the initial value is positive. Also the converse is true (if we assume that A has a non-empty resolvent set and D(A) n E+ is dense in £+). Moreover, every positive resolvent is a Laplace-Stieltjes transform of a so-called integrated semigroup; and conversely every such (increasing, non-degenerate) integrated semigroup defines a unique resolvent positive operator.

Prevention of colonization and respiratory infections in long-term ventilated patients by local antimicrobial prophylaxis.

Abstract: In a randomized clinical trial the prophylactic effects of locally administered antimicrobials on quantitative colonization and respiratory infections were studied in intubated patients with an expected period of mechanical ventilation of >6 days. Nineteen patients received 50 mg of polymyxin B and 80 mg of gentamicin distributed among nose, oropharynx and stomach at 6-h intervals, as well as 300 mg of amphotericin B in the oropharynx. Twenty untreated patients served as controls. In the control group colonization by respiratory pathogens was more common (oropharynx 19 vs 6 patients (p(0.001); trachea 19 vs 11 (p(0.01)), and the number as well as the count of the colonizing species was usually higher. Fourteen patients of the control group developed respiratory infections, including nine cases of pneumonia, as compared to four patients with prophylaxis, including one case of pneumonia (p(0.01). Pneumonia-associated deaths were prevented with prophylaxis; however, the overall mortality remained unchanged. Respiratory infections in the prophylaxis group were associated with organisms resistant to the agents used, but the overall occurrence of resistance was not increased, as compared to the control group. We conclude that unrestrained upper airway colonization by respiratory pathogens and respiratory tract infection were causally related. Local antimicrobial prophylaxis proved to be a highly effective strategy for the prevention of potentially life-threatening pneumonias in critically ill patients but in the present study the host setting appeared to be the major determinant of outcome.

The cytochrome oxidase subunit I and subunit III genes in Oenothera mitochondria are transcribed from identical promoter sequences

Abstract: Two loci encoding subunit III of the cytochrome oxidase (COX) in Oenothera mitochondria have been identified from a cDNA library of mitochondrial transcripts. A 657-bp sequence block upstream from the open reading frame is also present in the two copies of the COX subunit I gene and is presumably involved in homologous sequence rearrangement. The proximal points of sequence rearrangements are located 3 bp upstream from the COX I and 1139 bp upstream from the COX III initiation codons. The 5'-termini of both COX I and COX III mRNAs have been mapped in this common sequence confining the promoter region for the Oenothera mitochondrial COX I and COX III genes to the homologous sequence block.

Discovery of hard X-ray emission from supernova 1987A

Abstract: We report the discovery of hard X-rays from the region of the supernova SN1987A in the Large Magellanic Cloud. The observations were made from the Mir-Kvant observatory 'Rontgen'. Hard X-rays were first observed on 10 August 1987 and SN1987A then became the main target of the observatory. Up to 15 September 1987, a total of 115 pointings on 21 days were made. The flux showed little variation during the observation period. The measured spectrum extends from 20 keV to 300 keV and is extremely hard, having a photon power law index of ˜1.4. At low energies the spectrum becomes even flatter and there is indication of a cutoff between 10 and 25keV. The luminosity over the energy range 20–300 keV is ˜2x1038 erg s–1 (assuming a distance of 55 kpc). The error box for the hard source has a (2σ) radius of 10 arc min and contains SN1987A. The results have important implications for current models of SN1987A.

Pain and families. I. Etiology, maintenance, and psychosocial impact

Abstract: This is the first part of a two-part extended review on the interdependency between chronic pain and families. This paper will address the role of the family in the etiology and maintenance of chronic pain and will describe the reciprocal impact of chronic pain on families. Different conceptualizations of the role of the family and the available empirical evidence related to 3 central questions, namely, 'do families play an etiological role in chronic pain?,' 'does the family maintain the chronic pain problem?,' and 'is there a negative impact of chronic pain on the family?' will be critically examined. The second, companion paper will address the issue of the inclusion of family members in the assessment and treatment of chronic pain. Finally, recommendations for future research will be made.

The echolocation and hunting behavior of the bat,Pipistrellus kuhli

Abstract: The echolocation and hunting behavior of Pipistrellus kuhli was studied in the field using multi-exposure photography synchronized with high-speed tape recordings During the search phase, the bats used 8-12 ms signals with sweeps (sweep width 3-6 kHz) and pulse intervals near 100 ms or less often near 200 ms The bats seemed to have individual terminal frequencies that could lie between 35 and 40 kHz The duty cycle of searching signals was about 8% The flight speed of hunting bats was between 40 and 45 m/s The bats reacted to insect prey at distances of about 70 to 120 cm Given the flight speed, the detection distance was estimated to about 110 to 160 cm Following detection the bat went into the approach phase where the FM sweep steepened (to about 60 kHz bandwidth) and the repetition rate increased (to about 30 Hz) The terminal phase or 'buzz', which indicates prey capture (or attempted capture), was composed of two sections The first section contained signals similar to those in the approach phase except that the pulse duration decreased and the repetition rate increased The second section was characterized by a sharp drop in the terminal frequency (to about 20 kHz) and by very short pulses (03 ms) at rates of up to 200 Hz Near the beginning of the buzz the bat prepared for capturing the prey by extending the wings and forming a tail pouch A pause of about 100 ms in sound emission after the buzz indicated a successful capture (Fig 4)(ABSTRACT TRUNCATED AT 250 WORDS)

Plastid, nuclear and reverse transcriptase sequences in the mitochondrial genome of Oenothera: is genetic information transferred between organelles via RNA?

Abstract: We describe an open reading frame (ORF) with high homology to reverse transcriptase in the mitochondrial genome of Oenothera. This ORF displays all the characteristics of an active plant mitochondrial gene with a possible ribosome binding site and 39% T in the third codon position. It is located between a sequence fragment from the plastid genome and one of nuclear origin downstream from the gene encoding subunit 5 of the NADH dehydrogenase. The nuclear derived sequence consists of 528 nucleotides from the small ribosomal RNA and contains an expansion segment unique to nuclear rRNAs. The plastid sequence contains part of the ribosomal protein S4 and the complete tRNA(Ser). The observation that only transcribed sequences have been found i more than one subcellular compartment in higher plants suggests that interorganellar transfer of genetic information may occur via RNA and subsequent local reverse transcription and genomic integration.

Ferrous iron transport mutants in Escherichia coli K12

Abstract: A ferrous iron transport system in Escherichia coli is described. Mutants in this transport system were isolated using the antibiotic streptonigrin. The gene locus feo (for ferrous iron transport) was mapped near pncA at 38.5 min on the genetic map of E. coli K12. The transport of ferrous iron was regulated by fur as the siderophore transport systems.

Threshold models of temporal-order judgments evaluated by a ternary response task.

Abstract: This article examines various predictions of temporal-order judgment models (triggered-moment, attention-switching, and perceptual-moment models). These model tests are based on a ternary response-category approach: In each trial two stimuli (e.g., a tone and a light) are presented at times tx and ty, respectively. The time difference d = ty-tx was varied for each trial. After each presentation the subject selected one of three possible responses (“tone and light simultaneously,” “tone first,” or “light first”). Two psychometric functions can be generated from these response categories. It is shown that several models of temporal-order judgments constrain the relationship between these two functions. It was examined for different data sets whether the predicted relationships are satisfied. Several violations of the predicted relationships were observed, providing strong evidence against perceptual-moment models, triggered-moment models, and certain versions of attention-switching models. The proposed tests for each model do not depend on specific distributional assumptions of perceptual latencies. A modified attention-switching model with dwell times depending on stimulus properties might account for the present findings.

Distinct Substrate Specificity of Dihydroflavonol 4-Reductase from Flowers of Petunia hybrida

Abstract: Dihydroflavonol 4-reductase from Petunia flowers catalyzes the reduction of dihydroquercetin to leucocyanidin and, in particular, of dihydromyricetin to leucodelphinidin, whereas reduction of the simple dihydroflavonol dihydro- kaempferol to leucopelargonidin could not be observed. This special substrate specificity of dihydroflavonol 4-reductase is most probably the reason for the observations that delphinidin derivatives are the main end products of anthocyanin biosynthesis in Petunia flowers, whereas an- thocyanins based on pelargonidin are rarely found and, if present, are only formed in very small amounts.

Cerebral hemodynamics in angioma patients: an intraoperative study.

Abstract: ✓ Local hemodynamics were investigated during 33 operations for cerebral arteriovenous malformation (AVM). In all cases, microvascular Doppler sonography was used to measure flow velocities and vasomotor reactivity to CO2 changes. Intravascular pressure recordings were performed in six patients. The AVM feeders had low intravascular pressure, high flow velocity, low peripheral stream resistance, and very poor vasomotor reactivity. Remote brain arteries showed no abnormalities. Doppler findings in arterial branches of AVM feeders that supplied normal brain indicated arteriolar dilation in their peripheral distribution. On removal of the angiomas, the arteries that formerly supplied them showed a return to normal intravascular pressure, whereas flow velocities dropped far below normal in these vessels. Remote arteries and branches of the former AVM feeders supplying the brain did not show any signs of impaired vasomotor reactivity following angioma removal. The results are in contrast to the normal perfusio...

An in vitro method for establishing mycorrhizae on coniferous tree seedlings

Abstract: A method for in vitro synthesis of mycorrhizae on coniferous tree seedlings is described. Tree seedlings (Larix decidua Mill., Picea abies (L.) Karst, and Pinus sylvestris L.) and fungi Amanita muscaria (L. ex Fr.) Hooker, Piloderma croceum Erikss. et Hjorst., Pisolithus tinctorius (Pers.) Coker et Couch, and Suillus grevillei (Klotzsch) Singer were maintained under sterile conditions in petri dishes. Typical ectomycorrhizae were established within 2–3 weeks after inoculation and within 2 months after germination of seedlings. Eventually a high percentage of mycorrhizal root tips was obtained.

Pain > pain behaviors: The utility and limitations of the pain behavior construct

Abstract: A great deal of attention has been given to the importance of learning factors in communications of pain and suffering—pain behaviors. The concept of pain behaviors has served a heuristic function, however, there remain a number of important questions to be answered regarding the assessment and conceptual limitations of the construct. These concerns and questions must be acknowledged if the construct is to be of use in enhancing our understanding of chronic pain syndromes and to be employed in treatment. Current conceptualizations of pain behaviors are examined and methods of assessing pain behaviors are evaluated. The validity and utility of the construct and its limitations are discussed. It is concluded that failure to consider psychosocial, psychophysiological, and medical-physical factors may lead to an inadequate understanding of the patient and results in inappropriate treatment interventions. Suggestions for refined understanding of the scope of the construct are provided.

On fermion gauge groups, current algebras and Kac-Moody algebras

Abstract: Representations of groups of loops in U(N), SO(N) and various subgroups are studied. The representations are defined on fermion Fock spaces, and may be regarded as local gauge groups in the context of the two-dimensional many-particle Dirac theory for charged or neutral particles with rest mass m/> 0. For m = 0, the representations are shown to give rise to type I® factors, while for m > 0 hyperfinite, type III~ factors arise. A key point in the structure analysis is a convergence result: We prove that suitably rescaled representers of certain nonzero winding number loops converge to the free Dirac fields. We also present applications to cyclicity and irreducibility questions concerning the Dirac currents, and to the representation theory of a class of Kac-Moody Lie algebras.

Proliferative potential of meningiomas determined with the monoclonal antibody Ki-67.

Abstract: In 30 meningiomas we investigated the proliferation rate of various subtypes with the monoclonal antibody Ki-67. Frozen sections were incubated with Ki-67 antibody using a modified Alkaline Phosphatase anti-Alkaline Phosphatase (APAAP)-technique and evaluation of proliferation rate was done by cell counting. Meningiomas of the meningiotheliomatous, fibrous and angioblastic subtype without atypical histological findings contained 1% or less proliferating cells. In recurent tumors, in transitional and in anaplastic meningiomas there is a marked increase of proliferating cells up to 20%. The distribution of marked cells varies in recurrent tumors and anaplastic meningiomas, and a focal proliferation of tumor cells was seen in meningiomas from transitional type. Immunohistological labelling of proliferating cells in meningiomas may allow a more precise prediction of the proliferation potential of each meningioma.

Different origins of cochlear efferents in some bat species, rats, and guinea pigs.

Abstract: The origin of olivocochlear efferents was studied in the rat, the guinea pig, and the bats Rhinolophus, Rhinopoma, Tadarida, and Phylostomus by retrograde labeling with HRP and the fluorescent dye fast blue. In all species with the exception of Rhinolophus rouxi two types of cochlear efferents could be found: small neurons located in the lateral superior olive (LSO) and larger ones located bilaterally in the periolivary region. In bats and rats small olivocochlear neurons (OCN) were found only in the ipsilateral LSO. In guinea pigs some small OCN were found also in the contralateral LSO. Large OCN were found in all animals except Rhinolophus. They were organized in a horseshoelike nucleus that extended in a rostrocaudal direction and bent rostrally around the medial superior olive (MSO). This nucleus contains several periolivary nuclei described separately by other authors. In Rhinol. rouxi somata of all olivocochlear efferents are concentrated in a single nucleus between the MSO and LSO, which we therefore call the nucleus olivocochlearis. This nucleus stains for acetylcholinesterase. We consider its neurons to be similar to small OCN, because they are small, associated with the LSO, and only ipsilaterally labeled. This fits well with the fact that Rhinolophus lacks an efferent innervation of outer hair cells (Bishop: Ph.D. Thesis, University of North Carolina, Chapel Hill, '86; Bruns and Schmieszek: Hear. Res. 3:27-43, '80), which are normally innervated by large OCN (Guinan et al: J. Comp. Neurol. 221:358-370, '83).

The uptake of acylated anthocyanin into isolated vacuoles from a cell suspension culture of Daucus carota.

Abstract: Anthocyanin-containing vacuoles were isolated from protoplasts of a cell suspension culture of Daucus carota. The vacuoles were stable for at least 2 h as demonstrated by the fact that they showed no efflux of anthocyanin. The uptake of radioactively labelled anthocyanin was time-dependent with a pH optimum at 7.5, and could be inhibited by the protonophore carbonylcyanide m-chlorophenylhydrazone. Furthermore, the transport was specific, since vacuoles from other plant species showed no uptake of labelled anthocyanin, and strongly depended on acylation with sinapic acid, as deacylated glycosides were not taken up by isolated vacuoles. Hence, it is suggested that the acylation of anthocyanin, which is also required for the stabilization of colour in vacuoles, is important for transport, and that acylated anthocyanin is transported by a selective carrier and might be trapped by a pH-dependent conformational change of the molecule inside the acid vacuolar sap.

The essentially commutative dilations of dynamical semigroups on M n

Abstract: For identity and trace preserving one-parameter semigroups {Tt}t≧0 on then×n-matricesMn we obtain a complete description of their “essentially commutative” dilations, i.e., dilations, which can be constructed on a tensor product ofMn by a commutativeW*-algebra.