Die Kinetik der Ionenaufnahme durch junge und alte Sprosse von Mnium cuspidatum

Zusammenfassung Die Kinetik der Ionenaufnahme durch junge und alte Sprosse von Mnium cuspidatum wurde untersucht. Die verschieden alten Sprosse unterscheiden sich vor allem durch das Vorhandensein einer aktiven Gipfelknospe bei den jungen Gametophyten, die bei den alten offenbar ihre Tätigkeit eingestellt hat. Im niedrigen Konzentrationsbereich (0–0,5 mM) haben jungen und alte Sprosse hyperbolische Isothermen der Ionenaufnahme, die sich etwas hinsichtlich der apparenten Michaeliskonstanten und der Maximalgeschwindigkeit unterscheiden. Im hohen Konzentrationsbereich (1–10 mM) ist der Unterschied qualitativ. Mit jungen Sprossen erhält man eine lineare oder exponentielle Isotherme, mit alten Sprossen eine hyperbolische Kurve. Der vermutete Einfluß der Gipfelknospe kann mit Effekten von Wuchsstoffen auf den Stofftransport zusammenhängen und läßt einen Einfluß dieser Regulationssysteme auf die Membranfunktion vermuten.

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The kinetics of ion uptake by young and old branches of mnium cuspidatum

Summary Isotherms of K(Rb)-, Cl- and SO₄-uptake by young and old branches of the moss Mnium cuspidatum were investigated. Old moss gametophytes from the 1966 vegetation period were collected in the forests surrounding Darmstadt from February to mid-April 1967 and from the 1967 season in late September 1967. Young plants were sampled from mid-April to the end of May 1967 and they were also grown by water culture of old plants.Both young and old branches have hyperbolic isotherms of ion uptake in the low concentration range (0–0.5 mM) (Fig. 1–3), which slightly differ in K _mand V _max (Table). Isotherms in the high range (1–10 mM), however, are drastically different, changing from linear or exponential with young moss branches to hyperbolic with old gametophytes (Figs. 1–3).The linear or exponential high-range isotherm obtained with young moss plants is compared with other examples reported in the literature (Fig. 4). As the leaflets of the moss plants, which constitute 2/3 of the fresh weight of the material used in the experiments, have well developed vacuoles, the correlation between hyperbolic isotherms and vacuolation does not apply here (Fig. 4a, Torii and Laties, 1966).The change in shape of the high-range moss isotherm with age resembles the change from exponential to hyperbolic kinetics in isolated potato discs during washing (Fig. 4b, Laties, Macdonald and Dainty, 1964). The events triggered by isolation of potato discs from the interior of the tuber may be similar to the changes in the moss material under the control of the terminal bud, which is only active in the young branches.The suggested influence of the active terminal bud of young moss plants on the ion absorption process of cells in the tissue may be related to effects of growth substances on translocation reported in the literature and may point to a direct effect of these regulatory systems on membrane function.In this respect the comparison of corn root stele and cortex is of interest. Isolated steles, both freshly isolated and after washing, have exponential isotherms in the high range (Fig. 4c), whereas cortex displays a hyperbolic isotherm which changes little with ageing (Lüttge and Laties, 1967). In contrast to the case in potato and moss materials, this phenomenon is not simply due to ageing but involves morphogenetic differences.Temperature is another factor which influences the shape of the high range isotherm. All examples discussed so far refer to experiments at room temperature. At low temperatures high-range isotherms for proximal root tissue or aged potato discs have an exponential shape (Torii and Laties, 1966; Laties, Macdonald and Dainty, 1964). It thus appears that the exponential isotherm of young moss branches indicates that as in freshly isolated potato discs or in corn root stele the metabolic high-range uptake system is not developed.

     

Absorption and long distance transport by isolated stele of maize roots in relation to the dual mechanisms of ion absorption

Summary Ion absorption and transport by intact roots, isolated cortex and isolated stele were compared shortly after tissue isolation and after aging. Absorption isotherms in the low and in the high concentration range show that in stripped-stele, which absorbs at a very low rate immediately after isolation, the capacity of system 1 but not system 2 is built up with aging. In agreement with this result analysis of individual fluxes across plasmamembrane and tonoplast reveals that only the influx from the medium into the cytoplasm increases considerably with aging of stele. Changes observed in aging excised roots and in isolated cortex are much less significant. In spite of the increase of absorption with aging by isolated stele, long distance transport, which is essentially passive through freshly stripped stele, decreases with aging. The reported results reflect the marked permeability of the plasmamembrane of fresh isolated stele, and demonstrate the importance of the cortex as a tissue collecting ions for long distance transport. New evidence for the theory of symplasmatic transport of ions into the xylem vessels is thus provided.

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Zusammenfassung Die Ionenaufnahme durch intakte Wurzeln, isolierte Rinde und isolierte Zentralzylinder und der Ferntransport durch intakte und entrind ete Wurzeln wurden verglichen, und zwar kurz nach der Isolierung und nach Altern der Gewebe. Frisch isolierte Zentralzylinder akkumulieren Io nen nur in ganz geringem Maße oder überhaupt nicht. Von den beiden Systemen der metabolischen Ionenaufnahme, die in einem niedrigen (System 1: bis 0,5 meq/l) und in einem hohen Konzentrationsbereich (System 2: 1-50 meq/l) die Geschwindigkeit der Ionenaufnahme durch intakte Wurzeln und isolierte Wurzelrinde bestimmen, entwickelt sich während des Alterungsprozesses in isolierten Zentralzylindern System 1, nicht aber System 2.In Übereinstimmung mit diesem Befund zeigt die Analyse der Einzelfluxe am Plasmalemma und am Tonoplasten, daß nur der Influx aus der Außenlösung in das Cytoplasma beim Altern der Zentralzylinder beträchtlich ansteigt. Veränderungen beim Altern von abgeschnittenen, intakten Wurzeln und isolierter Rinde sind viel weniger ausgeprägt.Obwohl die Ionenaufnahme beim Altern isolierter Zentralzylinder steigt, verringert sich der Ferntransport, der bei frisch isolierten Zentralzylindern rein passiv ist. Die mitgeteilten Ergebnisse zeigen die ausgeprägte Permeabilität frisch isolierter Zentralzylinder und demonstrieren die Bedeutung der Wurzelrinde als ein Gewebe, das Ionen für den Ferntransport sammelt. Auf diese Weise werden neue Anhaltspunkte für die Theorie des symplasmatischen Transportes der Ionen in die Gefäße gewonnen.

     

Ammoniten mit Kieferapparat und Radula aus Lias-Geschieben

Jaws and radula have been found in two adult microconch specimens of the Liassic ammonite speciesEleganticeras elegantulum (Young & Bird, 1828) from glacial drift boulders near Hamburg. They are more similar to those of recent dibranchiates than ofNautilus, the radula having seven longitudinal rows of teeth instead of thirteen in recentNautilus. Since bothOwens classification of the cephalopods into Dibranchiata and Tetrabranchiata according to the number of gills (which cannot be observed in fossil cephalopods) andSchwarz’ division into Ecto- and Endocochlia according to the (assumed) relative position of body and shell are rather unfortunate, the radula is suggested as a sound basis of classification. It is acceptable to paleo- as well as to neozoologists. As yet, the known evidence is sufficient for a twofold division only: Class Cephalopoda Subclass Lateradulata: Nautiloidea Subclass Angusteradulata: Ammonoidea Coleoidea     

Bellevalia ciliata (Cyr.) Nees (Hyacinthaceae) neu für Bulgarien

(Bellevalia ciliata was recorded in north-east Bulgaria south of the Dobrudsha, within field and steppe vegetation. Vegetation records and a distribution map are presented. Based on taxonomic studies it is proposed to combineB. ciliata, B. sarmatica (Pall.) Wor. andB. speciosa Wor. under the oldest nameB. ciliata (Cyr.) Nees.     

Relative contribution of promoter and intragenic sequences in the hormonal regulation of rat beta-casein transgenes

In order to identify DNA sequences responsible for the regulation beta-casein gene expression, lines of transgenic mice bearing the entire rat beta-casein gene and two rat beta-casein promoter chloramphenicol acetyltransferase (CAT) fusion genes have been established. All three transgenes have been shown previously to be regulated in a tissue- and stage specific manner. To investigate the relative contribution of promoter and intragenic sequences in the hormonal regulation of the beta-casein gene, mammary explant cultures derived from these lines of mice have now been performed, and the effects of PRL and glucocorticoids on transgene as compared with endogenous beta-casein gene expression have been quantified. After the addition of PRL to cultures performed in the presence of insulin and glucocorticoids, a 25- to 40-fold induction of endogenous mouse beta-casein mRNA was observed after 48 hr. A comparable greater than 25-fold induction of transgene expression after PRL addition was observed in explant cultures derived from a line of mice expressing the entire rat beta-casein gene. In contrast, PRL addition elicited only a 1- to 4.5-fold increase in CAT activity in cultures derived from two lines of mice bearing casein-CAT fusion genes with either 524 or 2300 base pairs of 5'-flanking DNA. In the presence of insulin, glucocorticoid or PRL addition alone increased endogenous beta-casein gene expression 2- to 2.5-fold and 5- to 10-fold, respectively, but only a 1.2- to 2.5-fold induction of CAT activity was observed for each hormone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of Phospholipids on Growth, Sporulation and Virulence of the Endoparasitic Fungi Drechmeria coniospora, Verticillium balanoides and Harposporium anguillulae in Liquid Culture

Verticillium balanoides mycelial growth was stimulated on solid corn meal agar (1.7 %) and in liquid corn meal broth (0.2 %) upon the addition of phospholipids at various concentrations. Sporulation differed with phospholipid products and was highest in pure corn meal. Drechmeria coniospora mycelial growth increased upon addition of phospholipids at all concentrations in solid or liquid culture. Sporulation increased at high concentration (1000 ppm) and decreased at low concentration (100 ppm) of phospholipids in the medium. For both fungi, infectivity of conidia produced in liquid culture decreased when compared to conidia from parasitized nematodes. Addition of phospholipids partly restored this effect. Harposporium anguillulae mycelial growth and sporulation was not affected by addition of phospholipids to solid or liquid corn meal medium.     

Cu(I)-thionein release from copper-loaded yeast cells

Summary The release of intact CU(I)₈-thionein from copper-resistant copper-loaded yeast cells, strain X 2180-1Aa, has been shown. This copper(I)-thiolate-rich protein was characterized and compared with the chemical and physicochemical properties of intracellular yeast Cu-thionein. The same molecular mass and stoichiometry of 8 mol copper atoms/mol protein was found. No detectable difference between the Cu-thioneins was seen in luminescence emission, electronic absorption in the ultraviolet region, chiroptical data or amino acid composition. The importance of stable Cu(I)-thiolates in Cu-thionein as a safe vehicle for transporting copper in a non-reactive manner is confirmed.