Showing papers by "Humboldt University of Berlin published in 1989"

Homology of 54K protein of signal-recognition particle, docking protein and two E. coli proteins with putative GTP-binding domains

Abstract: MOST proteins exported from mammalian cells contain a signal sequence which mediates targeting to and insertion into the mem-brane of the endoplasmic reticulum (ER)1,2. Involved in this process are the signal-recognition particle (SRP) and docking protein (DP), the receptor for SRP in the ER membrane1. SRP interacts with the signal sequence on nascent polypeptide chains and retards their further elongation1, which resumes only after interaction of the arrested ribosomal complex with the docking protein3,4. SRP is a ribonucleoprotein particle comprising a 7S RNA and six polypeptides with relative molecular masses (Mr) of 9,000 (9K) 14K, 19K, 54K, 68K and 72K (ref. 1). The 9K and 14K proteins are essential for elongation arrest and the 68K–72K heterodimer is required for docking to the ER membrane5. The 54K protein binds to the signal sequence when it emerges from the ribosome6,7. Docking protein consists of two polypeptides, a 72K α-summit (DPα) and a 30K β-subunit (DPβ)8. No components structurally homologous to SRP and docking protein have yet been found in yeast or Escherichia coli. To understand the molecular nature of the interaction between the signal sequence and its receptor(s) we have characterized a complementary DNA coding for the 54K protein of SRP. Significant sequence homology was found to part of DPα and two E. coli proteins of unknown function. The homologous region includes a putative GTP–binding domain.

Development and regional differentiation of the European vegetation during the Tertiary

Abstract: The Tertiary vegetation of Europe evolved from paratropical to warm-temperate and temperate forms in response to a progressive, non-linear, climatic cooling. Its vegetational forms are composed mainly of two separate ecological units: the evergreen, laurophyll “paleotropical geoflora” and the deciduous, broad-leaved “Arctotertiary geoflora”. The development of the Tertiary climate and its interaction with the vegetation are convincingly indicated by the geoflora's migration; the changes in its composition; and the development of the Tertiary forest, swamp, and aquatic plant communities. The “paleotropical geoflora” is characterized in the upper Cretaceous to the upper Miocene by paratropical rain forest, subtropical rain and laurel forests, temperate laurel forests and edaphically-mediated formation of laurel-conifer forests. The “Arctotertiary geoflora” advanced into Europe in waves since the Paleocene and formed the basis for the Tertiary mixed mesophytic forests. These can be divided into warm-temperate rain forests, oak-hornbeamchestnut or mixed beech-oak-hornbeam forests, and edaphic formations such as bottomland and swamp forests. Beginning in the lower Cretaceous, the hydrophytic vegetation developed independently of the forest vegetation and formed very diverse herbaceous fresh water, swamp, salt water, and coastal formations. Considerable differences in composition allow to separate floral regions and provinces in Eurosiberia. Instead of three ill-defined floral regions in the Paleocene, there are four well-defined floral regions in the Pliocene. A Mediterranean region cannot be recognized, although Mediterranean (eumesogeic) floral elements appear in the Eocene/Oligocene and thereafter. The Mediterranean sclerophyll forests probably arose after the destruction of the laurophyll forests during the Pleistocene.

Biomechanics of the SB Charité lumbar intervertebral disc endoprosthesis.

Abstract: The SB Charite intervertebral disc prostheses consist of two metal end-plates and an interposed polyethylene slide core. These were subjected to static and dynamic testing in a servohydraulic test rig. When embedded in polypropylene, the prostheses were found to function adequately under a high static load, and under a lighter dynamic load for a long time. When tested in a cadaveric vertebral segment, a large end-plate surface area proved to be of critical importance in preventing collapse of the prosthesis into the vertebral body.

A new procedure for fast electrochemical analysis of solid materials

Abstract: equal to the realistic mean experimental time for complete replication of MDV1 RNA up to the point when the replica release takes place [8]. This time is taken to be 15 s in realistic conditions. The time-dependent probabilities p=p( t ) for the most probable secondary structures at a given time are displayed in Fig. 2. The refolding transition occurs when a new secondary structure emerges with a higher probability. These transitions are indicated by numbers in Fig. 2. The correlation between these transitions and the most significant pause sites is revealed in Fig. 1. The pause site is found by simply locating the nucleotide in the replica sequence corresponding to the instant when two probability curves cross or when a new secondary structure with higher probability emerges, as is the case with transition indicated by "7" in Fig. 2. One can infer f rom this analysis that the pause sites considered occur as a consequence of the partial relaxation of effective binding of the growing chain to the enzyme.

DNA fingerprinting with the oligonucleotide probe (CAC)5/(GTG)5: somatic stability and germline mutations.

Abstract: DNA fingerprints were generated from various human somatic tissues and from peripheral blood of 179 children and their 80 parents using (CAC)5/(GTG)5 oligonucleotide probes. Whereas somatic stability of the fingerprint patterns was demonstrated, the average rate for germline mutations was estimated to be approximately 0.001 per DNA locus and gamete, with the three different restriction enzymes used. Seven out of eight mutations observed appeared to be of paternal origin.

A technique to study the electrochemistry of minerals

Abstract: Recently a new technique has been introduced to study the dectrochemistry of metals and alloys [1,2]. This socal led abrasive stripping voltammetry comprises a mechanical (abrasive) transfer of traces of the solid material onto the surface of a solid electrode and the following electrochemical oxidation or reduction of these traces with an appropriate measuring method (e.g., differential pulse voitammetry). It turned out that this technique is highly useful to study the electrochemistry of sparingly soluble salts, including a great variety of minerals. This method opens up new areas of research, not only because of the extreme fastness of measurements (including sample preparation) but also because of the superior quality of the voltammograms and the trace amounts of material (less than 1/tg) which are sufficient to perform the study. To know the electrochemistry of minerals is important for a deep understanding of the formation and transformation of minerals. It is not less important for a possible electrochemical metallurgy [3]. Last, but not at least, abrasive stripping voltammetry can develop toward an easy method for mineral identification [4] even in fieldwork. As an example the electrochemistry of the mineral boulangerite, PbsSb4SI1 (Neumtihle, Greiz, GDR) will be discussed here. This mineral belongs to the extensive group of sulfo-salt minerals [5]. Figure 1 depicts the differential pulse voltammograms obtained after abrasive transfer of trace amounts of the mineral onto the surface of a paraffine-impregnated graphite electrode. Curve A is the cathodic voltammogram with the reduction of boulangerite according to

Paleogeography and historical phytogeography (paleochorology) in the Neophyticum

Abstract: After presenting the methodological bases of historical phytogeography (paleochorology; Fig. 1), a new paleographic map series is introduced (Fig. 2). They serve for ten examples of paleochorological analyses, in which the major phases of the development of a group in space and time are documented. In addition to purely tropical taxa (Nypa, Ctenolophon),others which originated in the warm and humid N. Tethyan belt (Bombacaceae p.p., Olacaceae p.p., Symplocos, Alangium, Nepenthes) or which presently occur as eastern N. American/E. Asian disjuncts (Sarcococca and Pachysandra) are discussed (Figs. 3 – 14).Finally, analyses of two very old angiosperm groups with complicated paleochorological patterns (Restionaceae and Ascarina, Chloranthaceae p.p.; Figs. 15 – 16) are presented.

A generalization of Wegscheider's condition. Implications for properties of steady states and for quasi-steady-state approximation

Abstract: A generalization of Wegschcider's condition concerning equilibrium constants in chemically reacting systems is formulated, which is then proved to be a necessary and sufficient condition for detailed balancing. In order to include a large multitude of rate laws, a generalized mass action kinetics is considered which comprises usual mass action kinetics and all reversible enzyme kinetics and which is consistent with basic postulates of irreversible thermodynamics for ideal mixtures. Reaction systems of arbitrary stoichiometry are considered. They may contain reactants with fixed concentrations, as is characteristic for models of biochemical reaction networks. Existence, uniqueness, and global asymptotic stability of equilibrium states for reaction systems endowed with generalized man action kinetics are proved. Using these results, he generalized Wegscheider condition is shown to be a sufficient criterion for the applicability of the quasi-steady-state approximation.

Daphnia and toxic blooms of Microcystis aeruginosa in Bautzen Reservoir (GDR)

Abstract: As a part of a whole-lake, long-term experiment in biomanipulation in. the hypertrophic Bautzen reservoir (G.D.R.), during three years (1984–1986) the dynamics of mouse-related LD 50 of Microcystis aeruginosa was compared with the biomass development of this blue-green and the grazing pressure exerted by Daphnia galeata. Since the three summer averages of the biomass of D. galeata revealed strong differences due to decreasing predation activity of fish from 1984 to 1986, the effects of different grazing pressure on Microcystis toxicity could be investigated under field conditions. Microcystis was nontoxic at the beginning of the growing season and developed high toxicity during its first strong biomass increase in summer in all three years. But this decrease of the LD 50 together with the first biomass increase of the season is found in quite different periods in different years (1984: August, 1985: July, 1986: June). It is obvious that the higher the mean effective filtration rate of D. galeata during summer is found the faster the toxicity of Microcystis is formed. If these observations are combined with findings of other authors, the conclusion can be drawn that the development of toxic Microcystis blooms seems to be promoted by a combination of five conditions: (1) Presence of a mixture of toxic and nontoxic Microcystis strains at the beginning of the growing season even if the portion of toxic strains is very low, (2) physical and chemical growth conditions which favour Microcystis over other phytoplankton, (3) high grazing pressure by zooplankton on edible food particles over a rather long period, (4) patchy distribution of the different Microcystis strains if nonselective filtrators such as Daphnia dominate the zooplankton, and (5) absence of defense mechanisms of Microcystis against grazing which are not coupled with toxicity (e.g. large colony size). These conclusions contribute to a better understanding of the possibilities and limits of in-lake eutrophication control by biomanipulation and emphasize the need to combine top-down and bottom-up control mechanisms in eutrophic and hypertrophic waters.

Modified Branching Programs and Their Computational Power

Abstract: Preliminaries.- Branching programs and their computational power.- Nondeterministic branching programs.- ?=branching programs and theirs computational power.

Effects of continuous and pulsed microwave irradiation on distribution of heat in the gluteal region of minipigs. A comparative study.

Abstract: Eleven experiments were conducted on minipigs for the purpose of determining heat distribution in tissue exposed to therapeutic doses of microwaves. Temperatures were measured by means of coated thermocouples from the cutis, subcutis, musculature, and periost. Irradiation was applied to intensities of 10 W, 40 W and 60 W by means of a "Radarmed 12 S 251" circular emitter and to 60 W, 100 W and 140 W, using a trough emitter. Maximum temperature in superficial tissue layers was reached after five to ten minutes of microwave exposure. The temperature rise in the cutis and subcutis was steeper and at a higher rate than that in the muscles. Continuation of microwave irradiation did not cause any further rise in temperature, which was attributed to induction of hyperaemia. No difference regarding heat distribution was found to exist between pulsed and continuous irradiation at equal wattage.

Identification of solid materials with a new electrochemical technique — the abrasive stripping analysis

Abstract: A new technique for the characterization of solid materials is proposed, consisting in the transfer of extremely small amounts of the solid substance by abrasion onto the surface of a suitable solid electrode. The abrased material is electrochemically stripped off and this process is traced with a voltammetric method, e.g., differential pulse voltammetry. The method allows the easy and fast identification of solid materials, avoids the dissolution of the sample and hence reveals information about the structure of the solid material, thus allowing electrochemical phase analysis. The proposed technique of abrasive stripping analysis is applicable to a wide range of inorganic and organic substances.

Hybrid bacillus endo-(1–3, 1–4)-β-glucanases: Construction of recombinant genes and molecular properties of the gene products

Abstract: Hybrid β-glucanase genes were constructed by the reciprocal exchange of the two halves of the isolated β-glucanase genes from Bacillus amyloliquefaciens and B. macerans. The β-glucanase hybrid enzyme 1 (H1) contains the 107 amino-terminal residues of mature B. amyloliquefaciens β-glucanase and the 107 carboxyl-terminal amino acid residues of B. macerans β-glucanase. The reciprocal β-glucanase hybrid enzyme 2 (H2) consists of the 105 amino-terminal residues from the B. macerans enzyme and the carboxyl-terminal 107 amino acids from B. amyloliquefaciens. The biochemical properties of the two hybrid enzymes differ significantly from each other as well as from both parental β-glucanases. Hybrid β-glucanase H1 exhibits increased thermostability in comparison to other β-glucanases, especially in an acidic environment. This hybrid enzyme has maximum activity between pH 5.6 and 6.6, whereas the pH-optimum for enzymatic activity of B. amyloliquefaciens β-glucanase was found to be at pH 6 to 7 and for B. macerans at pH 6.0 to 7.5 Hybrid enzyme 1 being more heat stable than both parental enzymes represents a case of intragenic heterosis. Hybrid β-glucanase 2 (H2) was found to be more thermolabile than the naturally occurring β-glucanases it was derived from and the pH-optimum for enzymatic activity was determined to be between pH 7 and pH 8.

Colored noise driven systems with inertia

Abstract: We present a novel approximation scheme, termed unified colored noise approximation (UCNA), for colored Gaussian noise driven nonlinear systems with inertia. This approximation allows one to evaluate static (stationary distributions, moments) as well as dynamical quantities (correlation functions) for small-to-moderate-to-large values of the correlation time. The approximation replaces a three-dimensional Markovian process by a reduced, two-dimensional Markovian dynamics with new drift and diffusion coefficients. For a harmonic potential the stationary moments are reproduced exactly. Most importantly, we present a criterion involving the noise strengthD, the friction strength γ and the noise color τ, which describes the region of validity of UCNA in the parameter space given by (D, τ, γ). At small τ-values we contrast the UCNA with the well-known small τ approximation. In order to have a comparison onanalytical grounds, we test the static and dynamical predictions of UCNA versus the well-known analytical results obtained from a three-dimensional Ornstein-Uhlenbeck process.

Abrasive stripping voltammetry — the electrochemical spectroscopy for solid state: application for mineral analysis

Abstract: Abrasive stripping voltammetry possesses several features of a spectroscopy. It allows the qualitative and quantitative analysis of electroactive solid materials. This work is focussed on the application for the unambiguous identification of minerals (sulphides, sulfo-salt minerals, fahlores). μg-amounts of a mineral are sufficient to perform a series of measurements. Three different voltammetric modes were used to study the electrochemical behaviour of the minerals.

Functional Properties of Linseed Protein Products Containing Different Levels of Mucilage in Selected Food Systems

Abstract: High-mucilage protein concentrates (HMPC) from linseed and linseed expeller cake had a good emulsion stabilizing effect in canned fish sauce and performed relatively better than a low-mucilage protein isolate (LMPI). Low-mucilage flour (LMF) and protein concentrate (LMPC) as well as the HMPC samples and LMPI reduced cooking loss of meat emulsion and firmness of the cooked emulsion. Overall, LMF and LMPC performed better than other linseed products in meat emulsion. In ice cream, the HMPC samples and LMPI had a stabilizing effect comparable to that of gelatin.

[Primary tumors of the choroid plexus. Frequency, localization and age].

Abstract: In 30 years, from 1956 through 1985, 155 primary tumours of the choroid plexus were first reported for entry into the National Cancer Registry of the GDR, with 125 of them having been identified as plexus papillomas and 30 as plexus carcinomas A total of 304 per cent of all plexus papillomas was diagnosed in patients in the first decade of life, half of them during the first year of life A lateral ventricle was the site from which 789 per cent of the plexus papillomas in the first decade were recorded Among all plexus tumours 394 per cent were detected only on postmortem investigation The number of plexus tumours reported for entry into the National Cancer Registry had continuously grown in the period under review, which, however, did not necessarily suggest increasing incidence of such tumours in the general population Possible factors of influence are discussed in some detail, for example, completeness of recording The number of plexus tumours reported in children up to three years of age rose with significance, between 1981 and 1985 This is assumed to have possibly been the consequence of an aetiological factor The average annual incidence (crude rate) of plexus tumours at GDR level was found to be 03 to one million (036 among males and 025 among females) Reasons are given that might support the assumption that real incidence has been above these values

Mathematical modelling of metabolic pathways affected by an enzyme deficiency. Energy and redox metabolism of glucose-6-phosphate-dehydrogenase-deficient erythrocytes.

Abstract: The effects of various forms of glucose-6-phosphate dehydrogenase deficiency on erythrocyte metabolism have been studied on the basis of a complex mathematical model which comprises the main pathways of this cell: glycolysis, pentose pathway, reactions of the glutathione and adenine nucleotide metabolism. The calculated flux rates through the oxidative pentose pathway with and without methylene blue are in good accord with experimental results. The degree of deficiency as predicted by the model on the basis of calculated upper oxidative load boundaries, as well as of maximal methylene blue stimulation, correlates with the individual clinical manifestation of the metabolic disease. Therefore, the model allows one to judge the degree of metabolic disorder in the presence of glucose-6-phosphate dehydrogenase enzymopathies if the kinetic properties of the defect enzyme are known. Experimentally accessible parameters for an assessment of the oxidative load capacity of cells in vivo are proposed. It is pointed out that the threshold of tolerance as to energetic load is drastically reduced in the case of severe glucose-6-phosphate dehydrogenase deficiency.

The genus Buxus ( Buxaceae ): Aspects of its differentiation in space and time

Abstract: Trends of pollen grain aperture evolution and exine characters as well as characters of leaf venation, petiole and axial vascularization are briefly described and related to geographical distribution and classification ofBuxus. A review of fossil records is given. Three major taxonomic groups can be delimitated within the genus, and aspects of their relationships and chorogenesis are presented. The level of differentiation, the pattern of distribution and the fossil record speak in favour of an ancient origin of the genus.

Developmental Pattern of Prosocial Motivation A Cross-National Study

Abstract: Changes in patterns of prosocial motivation between Grades 2 and 12 were examined in five samples from four countrics: West Germany, Poland, Italy,and the United States. The Prosocial Motivation Questionnaire (PSMQ), an instrument based on theoretical elaborations about evaluative standards operative in prosocial action, was used to assess within-subject preference for five prosocial motives: hedonism, self-interest, conformity, task orientation, and other-orientation. Studied were two samples from Berlin (West; average age range, 11-6 to 18-6 years) and one sample each from Warsaw (11-11 to 18-11), Bologna (11-6 to 18-11), and Phoenix, Arizona (8-4 to 13-4). The major results held for all cities studied and confirm the generalizability of earlier national findings. Specifically, the major findings were as follows: (1) extrinsic motives for prosocial acts (hedonism and self-interest) were least preferred, whereas intrinsic motives (task and other-orientation) were most highly valued, and conformity was al...

Prevalence of cholelithiasis. Results of an epidemiologic study using sonography in East Germany

Abstract: In two middle-sized towns in the northern part of the German Democratic Republic, a random sample of the population and unselected subjects, respectively, were examined for gallbladder stones (GS) by ultrasound. The prevalence of cholelithiasis (sum of GS detected by ultrasound and history of cholecystectomy for GS) ist higher than in other European populations screened by similar methods. It is suggested that dietary habits are responsible for this finding. About one third of subjects with GS had complications of GS and about one third gave a history of cholecystectomy for GS. The frequency of nonspecific dyspeptic complaints was the same in persons with GS as in persons without GS.

Index-2 Differential-Algebraic Equations

Abstract: A class of general nontransferable differential-algebraic equations which contains all linear differential-algebraic equations having the global index 2 in the definition of Gear and Petzold or being tractable with index 2 in the sense of Griepentrog and Marz as well as nonlinear index-2 equations in the understanding of Brenan, Gear, Petzold and further authors is characterized by a uniform matrix criterion. Existence and uniqueness statements are proved.