Showing papers by "Leibniz Association published in 1994"

The FUS3 gene of Arabidopsis thaliana is a regulator of gene expression during late embryogenesis

Abstract: The fus3 mutation of Arabidopsis thaliana affects several aspects of seed development. Mutant seeds are desiccation intolerant, viviparous and accumulate anthocyanins. Two major classes of storage proteins, the 12S cruciferins and the 2S albumins, are nearly absent, storage lipids are reduced and their composition is changed. The transcription of heterologous storage protein gene promoters in a fus3 genetic background is similarly affected. Our data suggest that the FUS3 gene is together with other genes like ABI3 and LEC1 central to the regulation of developmental processes during late embryogenesis.

Properties of the Log-Normal Particle Size Distribution

Abstract: This note presents analytical relationships that connect the parameters of any moment of the log-normal distribution to those of any other, allowing one to harmonize experimental data derived with varying particle sensors. They also make possible calculating essential aerosol parameters that may not be amenable to direct measurements.

Phloem translocation of Fe, Cu, Mn, and Zn in Ricinus seedlings in relation to the concentrations of nicotianamine, an endogenous chelator of divalent metal ions, in different seedling parts

Abstract: During the first 8 days of germination the Ricinus seedling is supplied with all nutrients by the endosperm via phloem transport. In 4- to 8-days-old seedlings the concentrations and contents of Fe, Cu, Mn and Zn, and nicotianamine (NA) in the endosperm, cotyledons, hypocotyl and roots were estimated. From the data obtained translocation rates and flow profiles for the metals were established. The main sink for Fe, Mn and Zn were the cotyledons whereas Cu was mainly imported into the hypocotyl. Maximum flow rates occurred between days 5 and 7, for Zn between days 6 and 8.

Cardiomyocyte-like cells differentiated in vitro from embryonic carcinoma cells P19 are characterized by functional expression of adrenoceptors and Ca2+ channels.

Abstract: P19 embryonal carcinoma cells were differentiated via embryolike aggregates (embryoid bodies) into spontaneously beating myocytes. During the whole process of differentiation the functional expression of cardiac-specific receptors and ionic channels was characterized by measuring the chronotropic reactivity, action potentials, and ionic currents in response to various cardioactive drugs. Positive chronotropic effects obtained at different maximal effective concentrations of adrenoceptor-mediated agonists indicated differential adrenoceptor expression during the in vitro development of cardiomyocyte-like cells. No cardiac-specific response was obtained with the muscarinic cholinoceptor agonist carbachol. Single beating cells were enzymatically isolated and investigated by the patch-clamp technique. Pacemaker action potentials similar to those of embryonal cardiomyocytes exhibited amplitudes ranging from 50 to 85 mV. The action potentials were synchronous to the mechanical contractions and, comparable to the chronotropic effects, were modulated by BayK 8644, isradipine, and adrenaline. The functional expression of L-type Ca2+ channels was demonstrated by the Ca2+ channel blockers isradipine, nisoldipine, gallopamil, and diltiazem causing negative chronotropic responses, as well as by the Ca2+ channel activator BayK 8644 causing positive chronotropic responses. These effects gradually increased with time of differentiation. The expression of L-type Ca2+ channels and of nicotinic acetylcholine receptors was confirmed in voltage-clamp experiments. The study demonstrates that P19 embryonal carcinoma cells can be induced to differentiate into cardiomyocyte-like cells comparable to embryonal and neonatal heart cells lacking the muscarinic cholinoceptor response only.

A chimeric gene encoding the methionine-rich 2S albumin of the Brazil nut (Bertholletia excelsa H.B.K.) is stably expressed and inherited in transgenic grain legumes.

Abstract: The coding region of the 2S albumin gene of Brazil nut (Bertholletia excelsa H.B.K.) was completely synthesized, placed under control of the cauliflower mosaic virus (CaMV) 35S promoter and inserted into the binary vector plasmid pGSGLUC1, thus giving rise to pGSGLUC1-2S. This was used for transformation of tobacco (Nicotiana tabacum L. cv. Petit Havanna) and of the grain legume Vicia narbonensis L., mediated by the supervirulent Agrobacterium tumefaciens strain EHA 101. Putative transformants were selected by screening for neomycin phosphotransferase (NPT II) and beta-glucuronidase (GUS) activities. Transgenic plants were grown until flowering and fruiting occurred. The presence of the foreign gene was confirmed by Southern analysis. GUS activity was found in all organs of the regenerated transgenic tobacco and legume plants, including the seeds. In the legume, the highest expression levels of the CaMV 35S promoter-controlled 2S albumin gene were observed in leaves and roots. 2S albumin was localized in the vacuoles of leaf mesophyll cells of transgenic tobacco. The Brazil nut protein was present in the 2S fraction after gel filtration chromatography of the legume seed proteins and could be clearly identified by immunoblotting. Analysis of seeds from the R2 progenies of the legume and of transgenic tobacco plants revealed Mendelian inheritance of the foreign gene. Agrobacterium rhizogenes strain RifR 15834 harbouring the binary vector pGSGLUC1-2S was also used to transform Pisum sativum L. and Vicia faba L. Hairy roots expressed the 2S albumin-specific gene. Several shoots were raised but they never completely rooted and no fertile plants were obtained from these transformants.

Characterization of Arxula adeninivorans strains from different habitats.

Abstract: SomeArxula adeninivorans strains selected from wood hydrolysates in Siberia, from soil in South Africa and from maize silage and soil in The Netherlands were compared. DNA-fingerprinting, pulse field gel electrophoresis as well as analysis of secretory proteins have been chosen to describe the similarities among the strains. Combination of the three methods allowed identification of each strain. Strains from the same origin show extensive similarities. The results of the DNA-fingerprints indicate that the strain isolated in Siberia belongs to the group of strains originated from South Africa. However, it differed in the molecular weight of the third chromosome and in the pattern of secretory proteins from the South African isolates.

Expression of Polarity during early Development of Microspore‐derived and Zygotic Embryos of Brassica napus L. cv. Topas

Abstract: Microspore derived (MS-)embryogenesis and zygotic embryogenesis of Brassica napus L. cv. Topas were investigated by light and scanning electron microscopy to reveal the expression of polarity during the transition phase from globular to heart and torpedo shape. During the first 5 days of MS-embryo formation, the cell wall of the former microspores remained intact and a globular mass of cells developed within. Pollen walls ruptured after 5 days of culture; embryos proceeded through heart-shape and torpedo-shape stages within 15 days in a way comparable to, but faster than observed during zygotic embryogenesis. Expression of polarity in globular and elongating MS-embryos was analyzed by detection of the distribution of activated calmodulin as well as of free cytosolic calcium by using confocal scanning laser microscopy, and by the detection of starch. Calmodulin was evenly distributed in globular embryos and only exhibited clear polar distribution in elongated embryos. Free cytosolic Ca2+ accumulated in the protoderm of globular embryos and in the central cylinder of torpedo shaped embryos, but never showed polar distribution. Accumulation of starch granules at the root poles of both sexual as well as MS-embryos, however, indicated polar distribution before the transition from globular to heart shape stage. Since the local rupture of the pollen wall of 6-day-old MS-embryos was never preceded by the decrease of starch at that site, it is likely that the rupture of the pollen wall plays an important role in the local activation of cell metabolism and thus in the determination of the polarity axis in MS-embryos.

Gibberellin conjugates : an overview

Abstract: This article surveys the currently isolated and identified GA conjugates, their synthesis and evaluates modern methods for analysing GA glucose conjugates. The metabolism of applied GAs in higher plant systems leading, in most cases, to GA conjugates is also considered. The enzymology of the formation and hydrolysis of GA glucose conjugates is discussed in connection with their possible physiological function.

Preparation, development of microstructure, electrical and gas-sensitive properties of pure and doped SnO2 powders

Abstract: The influence of bulk dopants (Nb, Mn, In and Pd) on the morphological, electrical and gas-sensing properties of SnO2 powders was observed. Comparing the specific surface areas of the powders observed by BET Nb-doping results in very fine powders. The electrical resistivity of SnO2 is decreased by Nb-doping and increased by bulk doping with either Pd, Mn or In. The existence of solid solutions in the systems doped with Nb, Mn and In is confirmed by single crystal experiments. The gas sensitivities are strongly correlated with the electrical resistivities of the sensor elements. The complex influence of dopants on the morphological and electrical properties of SnO2 is demonstrated by establishing a relation between the crystallite diameter, an evaluated carrier concentration, the number of electrons per crystallite and the thickness of the electron depletion layer. A limitation of bulk doping with electron-compensating elements for sensor optimization is given.

Polymerase chain reaction mediated localization of RFLP clones to microisolated translocation chromosomes of barley.

Abstract: A new strategy has been devised and used for the physical localization of genetically mapped restriction fragment length polymorphism (RFLP) clones to barley chromosomes. Morphologically distinct translocation chromosomes from synchronized root-tip meristems were microisolated and their DNA was used as a template for polymerase chain reaction with sequence-specific primers. Four RFLP clones were assigned to cytologically defined segments of chromosome 5. This related approximately one-third of the map length of linkage group 5 to approximately one-fifth of the mitotic metaphase length of chromosome 5. The technique may substantially contribute to the connection of the RFLP-based genetic linkage maps with cytological markers of the barley chromosomes.Key words: Hordeum vulgare, microisolated chromosomes, translocation, polymerase chain reaction, physical RFLP mapping.

Localization of translocation breakpoints in somatic metaphase chromosomes of barley

Abstract: Karyotype analyses based on staining by acetocarmine followed by Giemsa N-banding of somatic metaphase chromosomes of Hordeum vulgare L. were carried out on 61 reciprocal translocations induced by X-irradiation. By means of computer-based karyotype analyses all of the 122 breakpoints could be localized to defined sites or segments distributed over the seven barley chromosomes. The pre-definition of translocations with respect to their rearranged chromosome arms from other studies rendered it possible to define the break positions even in translocations having exchanged segments equal in size and the breakpoints located distally to any Giemsa band or other cytological marker. The breakpoints were found to be non-randomly spaced along the chromosomes and their arms. All breaks but one occurred in interband regions of the chromosomes, and none of the breaks was located directly within a centromere. However, short and long chromosome arms recombined at random. An improved tester set of translocations depicting the known break positions of most distal location is presented.

Opportunities for manipulating the seed protein composition of wheat and barley in order to improve quality

Abstract: Wheat and barley are the major temperate cereals, being used for food, feed and industrial raw material. However, in all cases the quality may be limited by the amount, composition and properties of the grain storage proteins. We describe how a combination of biochemical and molecular studies has led to an understanding of the molecular basis for breadmaking quality in wheat and feed quality in barley, and also provided genes encoding key proteins that determine quality. The control of expression of these genes has been studied in transgenic tobacco plants and by transient expression in cereal protoplasts, providing the basis for the production of transgenic cereals with improved quality characteristics.

De-embedding of MMIC transmission-line measurements

Abstract: The determination of transmission-line characteristic impedance and propagation constants from two-port S-parameter measurements is disturbed by half-wavelength resonances. We demonstrate this effect for on-wafer measurements of coplanar lines. Two networks representing end effects embed the line and strongly enhance the resonant effect. The de-embedding consists in determining these networks and subtracting them from the measured chain matrix. It is shown that simple shunt admittances are sufficient for modeling of the end effects. Three methods of de-embedding are presented. >

Enrichment of bovine X and Y spermatozoa by free-flow electrophoresis.

Abstract: Conditions of separation of bovine spermatozoa according to their differences in electrophoretic mobility were studied using free-flow electrophoresis. Distribution of spermatozoa in the electric field depends on composition of buffer system, field intensities and temperature. Conditions are described for reproducible separation of anodically migrating spermatozoa into two distinct peaks both for cold-immobilized (10-13 degrees C) and for motile cells (25 degrees C). Electrophoresis with the buffer used at 25 degrees C and field intensities of 70-100 V/cm provided high percentages of motile spermatozoa (50-90%) in all fractions. However, the sperm distribution across the fractions was the result of superimposed passive electrophoretic motion towards the anode and the active galvanotactic migration towards the cathode. Separation of X- and Y-spermatozoa was verified by quantification of Y-spermatozoa by means of both in situ hybridization, using Y-specific DNA fragments, and the Y-specific fluorescence staining (f-body test). Y-spermatozoa could be enriched in anodic fractions (112 and 144% relative to control). X-spermatozoa were enriched in cathodic fractions (80 and 68% Y-spermatozoa, as compared to control).

Sequence of a plant cDNA from Vicia faba encoding a novel Ran-related GTP-binding protein

Abstract: A clone obtained from a broad bean (Vicia faba) developing cotyledon cDNA library contained the complete coding sequence of a polypeptide with very high homology to the small GTP-binding proteins Ran from human cells and Spi1 from yeast. These proteins belong to the ras superfamily of proteins involved in different basic cellular processes. The Ran/Spi1 proteins interact with a protein bound to DNA (RCC1) and are thought to function in the regulation of the cell cycle. The amino acid sequence of the obtained plant Ran-homologue, designated Vfa-ran, is 74% and 76% identical to Ran and Spi1, respectively. The five functional, conserved domains of ras-related proteins are present in the Vfa-ran sequence. However, as in Ran/Spi1 the C-terminus of Vfa-ran is very acidic and lacks the Cys motif for isoprenylation. Northern blotting revealed a corresponding mRNA expression in broad bean roots, leaves, and cotyledons with the highest level in roots.

Cytosolic and plastid forms of 5-enolpyruvylshikimate-3-phosphate synthase in Euglena gracilis are differentially expressed during light-induced chloroplast development.

Abstract: The enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase (EC 25119), the target of the herbicide glyphosate [N-(phosphonomethyl)glycine], exists in two molecular forms in Euglena gracilis One form has previously been characterized as a monofunctional 59 kDa protein The other form constitutes a single domain of the multifunctional 165 kDa arom protein The two enzyme forms are inversely regulated at the protein and mRNA levels during light-induced chloroplast development, as demonstrated by the determination of their enzyme activities after non-denaturing polyacrylamide gel electrophoresis and Northern hybridization analysis with a Saccharomyces cerevisiae ARO1 gene probe The arom protein and its mRNA predominate in dark-grown cells, and the levels of both decline upon illumination In contrast, the monofunctional EPSP synthase and its mRNA are induced by light, the increase in mRNA abundance preceding accumulation of the protein The two enzymes are localized in different subcellular compartments, as demonstrated by comparing total protein patterns with those of isolated organelles Glyphosate-adapted wild-type cells and glyphosate-tolerant cells of a plastid-free mutant of E gracilis, W10BSmL, were used for organelle isolation and protein extraction, as these cell lines overproduce EPSP synthase and the arom protein, respectively Evidence was obtained for the cytosolic localization of the arom protein and the plastid compartmentalization of the monofunctional EPSP synthase These conclusions are further supported by the observation that EPSP synthase precursor, produced by in vitro translation of the hybrid-selected mRNA, was efficiently taken up and processed to mature size by isolated chloroplasts from photoautotrophic wild-type E gracilis cells, while the in vitro-synthesized arom protein was not sequestered by isolated Euglena plastids

The European badger (Carnivora:Mustelidae) as intermediate host of further three Sarcocystis species (Sporozoa).

Abstract: Trois especes de sarcocystes sont decrites au microscope optique et electronique chez le blaireau europeen (Meles meles): Sarcocystis hofmanni n. sp. (espece par ailleurs rencontree chez le chevreuil, Capreolus capreolus), S. sp., cf. sebeki (espece parasitant habituellement certains murides), et S. melis n. sp. (espece probablement specifique du blaireau)

Jasmonic acid and abscisic acid in shoots, coleoptiles, and roots of wheat seedlings

Abstract: The endogenous levels of abscisic acid (ABA) and jasmonic acid (JA) were analyzed in wheat seedlings grown in water, a system which in the past has been used to test the effects of these plant growth inhibitors. The levels in different plant parts and in the medium were measured by gas chromatography-mass spectrometry-selected ion monitoring, using [2H3]ABA and [2H6]JA as internal standards. In every plant part, JA levels were about 2 orders of magnitude greater than those of ABA. The exudation of JA from roots per seedling was about 14,000-fold greater than that of ABA, although the roots contained only about 170 times more JA than ABA. It is suggested that JA is a possible allelopathic compound.

The wisent (Bison bonasus, Bovidae) as an intermediate host of three Sarcocystis species (Apicomplexa: Sarcocystidae) of cattle.

Abstract: Sarocysts were found in muscle tissue of a wisent (Bison bonasus) which was born and kept in Germany. Light microscopic and TEM examination revealed all the three named species known from cattle: Sarcocystis cruzi ("thin-walled", with longer hair-like villar protrusions of the primary cyst wall); S. hirsuta ("thick-walled", with tongue-like protrusions of the cyst wall arising with very short and narrow stalklets from the surface of the cyst and containing rows of electron-dense granules in the core); and S. hominis ("thick-walled", with finger-like protrusions of the cyst wall not constricted at their base and containing few or no electron-dense granules). So far, only S. cruzi was known to occur in Bison bison in North America. The findings in the wisent strikingly support a modified conception of the intermediate host specificity in Bovinae. In this connection the identity of S. cruzi and S. poephagicanis is suggested as well as that of S. hirsuta and S. poephagi.

Are Vavilov's law of homologous series and synteny related?

Abstract: Synteny, the co-linear arrangement of genes in related taxa, shows parallelity to Vavilov's law of homologous series and possibly provides a molecular approach for the explanation of this law.