Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Ecological theories and Dutch nature conservation

This paper aims to achieve insight into various ecological theories in the Netherlands which have different, and sometimes opposing, views on the conservation of nature. Interviews, publications and archival research brought to light four separate theories: vitalistic/holistic, dynamic, cybernetic and chaos. Diversity is reached through stability according to vitalistic/holistic and cybernetic theories, but through change and instablility according to the dynamic and chaos theories. These two groups are working apart, and continue to have their own ideas. Prediction of the future is only possible with the vitalistic/holistic and cybernetic theories. Ecologists who adhere to these theories feel responsible and able in different ways to change ecological nature towards desirable end goals. The other two theories, dynamic and chaos, appear to be less activist.     

Invertebrate predator-prey body size relationships: an explanation for upper triangular food webs and patterns in food web structure?

Summary It has been suggested by Cohen and Newman (1985) that many of the patterns in published food webs can be derived from a stochastic model in which the species are arranged in a trophic hierarchy (the cascade model). We suggest that, if predators are larger than their prey, a trophic hierarchy can be generated on the basis of body size Empirical evidence from the literature shows that there is a positive relationship between predator and prey size for a range of invertebrates and that predators are usually larger than their prey. Using experimental data on an aquatic food web we show that body size can lead to the type of trophic hierarchy used in the cascade model, suggesting that many food web patterns may be a product of body size. This conclusion is discussed with respect to the limitations of the food web data and the relationship between static and dynamic models of web structure.     

Donor tissue and culture condition effects on mesophyll protoplasts of Medicago sativa

Mesophyll protoplasts were produced from clones of two cultivars of Medicago sativa, Rangelander and Regen S. Protoplasts from the Regen S clone generally gave rise to calli while those from the Rangelander clone would undergo direct embryogenesis. Effects of plant growth conditions, donor tissue pretreatment and protoplast culture conditions on mesophyll protoplast production and subsequent development patterns were investigated. The major factor determining whether or not mesophyll protoplasts would be produced from either of the clones was the pretreatment in water of shoots excised from the donor plants. Pretreatment in water containing growth regulators did not alter protoplast production or development in the Regen S clone. Pretreatment of the Rangelander clone shoots with abscisic acid or naphthaleneacetic acid was slightly beneficial to embryo production while pretreatment with benzylaminopurine was detrimental. Altered leaf morphology induced by growth condition changes did not affect mesophyll protoplast production or subsequent development patterns when shoots were pretreated in water. Culture of protoplasts in liquid droplets or solid agar medium increased low density protoplast survival and subsequent embryo production in the Rangelander clone.     

Phylogenetic Analysis of the Plant Endo-β-1,4-Glucanase Gene Family

Phylogenetic analysis of the endo--1,4-glucanase gene family of Arabidopsis and other plants revealed a clear distinction in three subfamilies (, , and ). The - and -subfamily contains proteins believed to be involved in a number of physiological roles such as elongation, ripening, and abscission. The -subfamily is composed of proteins that are predicted to have a membrane-spanning domain and to be localized at the plasma membrane. Some of these proteins have been linked to cellulose biosynthesis by serving to hydrolyze a lipid-linked intermediate that acts as a primer for the elongation of -glucan chains during cellulose synthesis at the plasma membrane. Similar glucanases are important in cellulose biosynthesis in bacteria. Searches in the genomes of unrelated organisms that make cellulose, such as Ciona intestinalis and Dictyostelium discoideum, revealed the presence of membrane-linked endo--1,4-glucanases and it is suggested that these might also have a role in cellulose synthesis.     

Klassifizierung mariner,brackiger und limnischer Grundwasserbiotope

Zusammenfassung 1. Das Küstengrundwasser stellt einen Übergangsbereich zwischen limnischen und marin beeinflußten Grundwasserbiotopen dar.2. Im limnischen, brackigen und marinen Mesopsammal beziehungsweise Mesopsephal wirken dieselben ökologischen Hauptfaktoren: Lichtlosigkeit und Ausmaß der Kavernengeräumigkeit. Diese ökologische Gemeinsamkeit gibt Anlaß, eine Gliederung der limnischen Grundwasserbiotope (Husmann 1966) zu einer Typologie der Gesamtheit limnischer, brackiger und mariner Subterranbiotope zu erweitern.3. Zur Gliederung der limnischen Grundwässer wird die Beschaffenheit des grundwasserführenden Substrates jeweils mit der Art und Weise zönologischer Einflüsse aus Oberflächengewässern, oder mit dem Fehlen derartiger Kontakte, in Beziehung gesetzt. Dabei ergeben sich die in Abbildung 1 genannten Bezeichnungen limnischer unterirdischer Biotope.4. Für eine Typologie der marin beeinflußten Interstitialgewässer — Thalassopsammal, Thalassopsephal — wird die Salinität des Interstitialwassers hinzugezogen.5. Unter Berücksichtigung der Vorbehalte vonDen Hartog (1964) wird dem Venedig-System hierzu nur beschränkte Geeignetheit zuerkannt.6. Eine Heranziehung des Venedig-Systems beschränkt sich auf Grundwasserbiotope der Meeresküste mit besonders ausgeprägter Stabilität der Salinität. Ein Beispiel für eine derartige Besonderheit gibt Abbildung 1.7. Eine Kombination der vorgeschlagenen Bezeichnungen brackiger Interstitialgewässer mit dem Typologischen System der Brackwässer (Den Hartog 1964) erscheint nach Möglichkeit angebracht. Beispiel: Lagunäres (mixo-)oligohalines Thalassopsammal.

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Classification of marine, brackish and limnic groundwater biotopes

The oligohaline groundwater of marine beaches (Küstengrundwasser;Remane) represents an ecological zone of contact between limnic and marine groundwater biotopes. In the Küstengrundwasser and in all other brackish, marine and limnic interstitial waters there are two principal ecological factors: darkness and dimension of interstitial volume. These ecological conditions suggest a comprehensive classification of limnic, brackish and marine groundwater biotopes (except saline subterranean inland waters). Freshwater subterranean biotopes are classified in regard to the nature of the substrate containing groundwater, and the nature of contact with surface waters. The classification of subterranean biotopes influenced by marine conditions is based on the same factors plus salinity of the interstitial water. The Venice system for classification of brackish water is considered to be of limited value. In general, brackish subterranean waters should only be classified as: oligohaline, mesohaline or polyhaline thalassopsammal. The usefulness of the Venice system classification is limited to marine-influenced groundwater biotopes with an extremely stable salinity.

     

Comparative salt tolerance in triticale,wheat and rye during germination

Summary Differences in salt tolerance of wheat and barley have been observed but knowledge of such differences in triticale (X Triticosecale Wittmack) cultivars is of potential importance. Effects of six salinity levels (0 to 2% NaCl) on germination of triticales Beagle and 6TA 131 in comparison to wheat and rye were determined at 15–20°C. Beagle triticale and rye showed similar trends in germination reduction as salinity increased from 0 to 1.5% NaCl and exhibited fairly high salt tolerance. However, 6TA 131 triticale and wheat showed a significant drop in germination even at 0.5% NaCl concentration and were more susceptible to salt injury.     

Use of15N/14N rations to evaluate the food source of the mysid,Neomysis intermedia Czerniawsky,in a eutrophic lake in Japan

The stable isotope ratios of nitrogen were measured in the mysid,Neomysis intermedia, together with various biogenic materials in a eutrophic lake, Lake Kasumigaura, in Japan throughout a year of 1984/85. The mysid, particulate organic matter (POM, mostly phytoplankton), and zooplankton showed a clear seasonal change in ¹⁵N with high values in spring and fall, but the surface bottom mud did not. A year to year variation as well as seasonal change in ¹⁵N was found in the mysid. The annual averages of ¹⁵N of each material collected in 1984/85 are as follows: surface bottom mud, 6.3 (range: 5.7–6.9); POM, 7.9 (5.8–11.8); large sized mysid, 11.6 (7.7–14.3); zooplankton, 12.5 (10.0–16.4); prawn, 13.2 (9.9–15.4); goby, 15.1 (13.8–16.7). The degree of¹⁵N enrichment by the mysid was determined as 3.2 by the laboratory rearing experiments. The apparent parallel relationship between the POM and the mysid in the temporal patterns of ¹⁵N with about 3 difference suggests the POM (mostly phytoplankton) as a possible food source ofN. intermedia in this lake through the year.     

Multiple shoot regeneration from root organ cultures of Populus alba x P. grandidentata

Excised roots of various ages from Crandon and Hansen clones of Populus alba x P. grandidentata were tested for their regeneration capacity. Sixty-day-old excised roots that contained root tips were found to be most suitable. The highest number of shoots (an average of 111 shoots/root segment with Crandon and 98 with Hansen) was obtained by adding 22M and 14M zeatin to the medium, respectively. The two clones of hybrid poplar responded similarly to growth regulator treatments; however, the number of shoots produced was greater from the root organs derived from Crandon clones. Regenerated shoots were rooted in basal Woody Plant Medium without any growth regulators. Successful transplantation into soil and growth was achieved with all plants.     

Residual motion of hemoglobin-bound spin labels and protein dynamics: viscosity dependence of the rotational correlation times

The residual motion of spin labels bound to cysteine 93 and to lysines of methemoglobin has been studied by electron paramagnetic resonance spectroscopy. To separate the influences of the solvent and the protein environment of the label fluctuations, the correlation times, , were analyzed as a function of temperature for fixed solvent viscosities, . Results show that over a wide range of viscosity the dependence of on may be empirically described by a power law ^k . The exponent k depends strongly on the location of the label on the protein surface. If one regards the spin labels as artificial amino acid side chains, characteristic values of correlation times and amplitudes of the rotational motion at the surface can be given. For =1 cP and T=297 K the correlation time of the labels bound to lysines is found to be =9 · 10^–10 s and the rotational diffusion is nearly isotropic. The spin label bound to cysteine 93 occupies a protein pocket, its rotational motion is therefore restricted. The correlation time of the label motion within a limited motion cone of semi angle =30° ± 3° is found to be =1.3 · 10^–9 s for =1 cP and T=297 K.     

The neutral carotenoids of wild-type and mutant strains of Neurospora crassa

The neutral carotenoids of wild-type Neurospora crassa and of carotenoid mutants at four discrete genetic loci were isolated using gradient elution chromatography on deactivated alumina columns. Carotenoids were identified by absorption spectrophotometry and thin layer cochromatography with carotenoid standards. Phytoene, phytofluene, -carotene, -carotene, neurosporene, torulene, lycopene, and 3,4-dehydrolycopene were isolated from wild type. Phytoene, phytofluene, -carotene, -carotene, neurosporene, -carotene, lycopene, and one unknown carotenoid, tentatively identified as 15,15-cis--carotene, were isolated from a yellow mutant, ylo-1. ylo-1 also contained residual carotenoids having similar absorption spectra to, but very different chromatographic behavior from, phytofluene, -carotene, -carotene, and lycopene. Albino and colored al-1 mutants contained large amounts of phytoene and only traces of other neutral carotenoids. Albino al-2 and al-3 mutants contained only traces of neutral carotenoids.     

Proteolytic digestion of α-lactalbumin: Physiological implications

The kinetics of the partial digestion of bovine -lactalbumin (-LA) by trypsin, -chymotrypsin, and pepsin was monitored by lactose synthase activity, HPLC, and difference spectrophotometry. The relative stabilities of the various metal-bound states of -LA to trypsin and chymotrypsin at 37 and 5°C decrease in the following order: Ca(II)--LA>Zn(II), Ca(II)--LA>apo--LA. The HPLC digestion patterns of Ca(II)--LA and Zn(II), Ca(II)--LA at 5 and 37°C were similar, while the corresponding digestion patterns for apo--LA were quite different, reflecting the existence of the thermally induced denaturation states of apo--LA within this temperature region. Occupation of the first Zn(II)-binding site in Ca(II)-loaded -LA slightly alters the HPLC digestion patterns at both temperatures and accelerates the digestion at 37°C due to Zn(II)-induced shift of the thermal transition of -LA, exposing some portion of thermally denatured protein. The results suggest that the binding of Zn(II) to the first Zn(II)- (or Cu(II))-specific site does not cause any drastic changes in the overall structure of -LA. The acidic form of -LA (atpH 2.2 and 37°C) was digested by pepsin at rates similar to that for the apo- or Cu(II), Ca(II)-loaded forms by trypsin or -chymotrypsin at neutralpH. Complexation of -LA with bis-ANS affords protection against pepsin cleavage. It is suggested that the protective effects of similar small lipophilic compounds to -LA may have physiological significance (e.g., for nutritional transport).On leave from the Institute of Biological Physics, USSR Academy of Sciences, Pushchino, Moscow Region, 142292, USSR.     

Modelling endplate currents: dependence on quantum secretion probability and decay of miniature current

Quantification of the time course and amplitude of endplate currents (EPC) was made with respect to dispersion of quanta secretion and to changes in the exponential decay of miniature endplate currents (_mepc). The relationship between RPC amplitude and _mepc follows a double-exponential curve with ₁= 0.3 ms and ₂ = 6 ms. If the amplitude of fully synchronised EPC is taken as 100%, then the loss of EPC amplitude is already 42% with physiological parameters of dispersion (the half-rise and decay constant of distribution of secretion probability = 0.5 ms, _mepc =1 ms). This loss is even more substantial if secretion is more dispersed or miniature endplate currents decay faster. Correspondence to: F. Vyskocil     

Existence and uniqueness of a sharp travelling wave in degenerate non-linear diffusion Fisher-KPP equations

In this paper we use a dynamical systems approach to prove the existence of a unique critical value c ^* of the speed c for which the degenerate density-dependent diffusion equation u _ct = [D(u)u _x ] _x + g(u) has: 1. no travelling wave solutions for 0 < c < c ^*, 2. a travelling wave solution u(x, t) = (x - c ^* t) of sharp type satisfying (– ) = 1, () = 0 ^*; '(^*–) = – c ^*/D'(0), '(^*+) = 0 and 3. a continuum of travelling wave solutions of monotone decreasing front type for each c > c ^*. These fronts satisfy the boundary conditions (– ) = 1, '(– ) = (+ ) = '(+ ) = 0. We illustrate our analytical results with some numerical solutions.     

Differential subcellular localization of ACTH and α-MSH in corticotropes of the rat anterior pituitary

Summary Specific antisera to -melanotropin (-MSH) and corticotropin (ACTH 1-39) were used to obtain immunocytochemical evidence for the differential localization of -MSH and ACTH in the secretory granules of corticotropes of rat anterior pituitary. The specificity of the antisera was established by binding ¹³¹I-labeled -MSH and ACTH 1-39 to their respective antisera. Double-labeling immunocytochemistry (for -MSH, ferritin; for ACTH, colloidal gold) was performed. Some secretory granules were labeled with ferritin particles (-MSH), whereas others contained gold particles (ACTH). Only a few granules showed both ACTH and -MSH. In typical corticotropes (stellate in form with a small number of secretory granules aligned along the cell periphery) only some of the secretory granules that were labeled with anti-ACTH serum were also immunoreactive to anti--MSH. In atypical corticotropes (polygonal in shape and containing a large number of secretory granules) almost all of the immunoreactive ACTH secretory granules were also positive to anti--MSH serum. An intermediate type of corticotrope was observed containing a small number of secretory granules, almost all of which were labeled with anti--MSH. Thus, rat anterior pituitary corticotropes may be classified into three types according to the distribution and content of -MSH. The light-microscopic immuncytochemistry provided similar results.     

Observations on the fine structure of the cercaria of Notocotylus attenuatus and formation of the cyst wall of the metacercaria

Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.     

Formation and ecological significance of aggregations in collembola

Summary Spatial distribution in the two collembolan species Tomocerus minor and Orchesella cincta is greatly influenced by the distribution of the environmental factors water and food. T. minor is totally restricted in distribution to water-saturated places, where it forms spaced-out aggregations. O. cincta assembles in water-saturated places during ecdysis and subsequent reproduction. This leads to dense contact-aggregations. Dispersal follows during the feeding period, probably caused by food shortage, presence of other species and/or saturated conditions in the aggregation site. After feeding, orientation toward water-saturated places occurs by means of orthokinetic reactions and the aggregations are reestablished. The effect of this periodical aggregation for the population is discussed.     

Gibberellins play a role in the interaction between imidazole fungicides and cytokinins in Araceae

Imidazole fungicides such as imazalil, prochloraz, and triflurnizole and the triazole growth retardant paclobutrazol promote the shoot-inducing effect of exogenous cytokinins in Araceae, such as Spathiphyllum floribundum Schott and Anthurium andreanum Schott. The mechanism of their action could partially be based on the inhibition of gibberellic acid (GA) biosynthesis, because administration of GA₃ inhibits the phenomenon completely in S. floribundum. Not only is the suppression of GA biosynthesis involved, but also the metabolism of endogenous cytokinins is significantly altered. Although the balance between isopentenyladenine, zeatin, dihydrozeatin, and their derivatives was shifted to distinguished directions by administration of BA and/or imazalil and/or GA₃, no correlation between these changes in metabolic pathways and the number of shoots could be found. The metabolism of BA was not significantly altered by adding imazalil to the micropropagation medium of S. floribundum.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - [9R-5P]DHZ 9--d-ribofuranosyl-dihydrozeatin-monophosphate - [9R-5P]iP 6-isopentenyl-9--d-ribofuranosyladenine-monophosphate - [9R-5P]Z 9--d-ribofuranosyl-zeatin-monophosphate - [9G]BA 6-benzyl-9--d-glucopyranosyladenine - [9G]DHZ 9--d-glucopyranosyl-dihydrozeatin - [9G]iP 6-isopentenyl-9--d-glucopyranosyladenine - [9G]Z 9--d-glucopyranosyl-zeatin - [9R]BA 6-benzyl-9--d-ribofuranosyladenine - [9R]DHZ 9--d-ribofuranosyl-dihydrozeatin - [9R]iP 6-isopentenyl-9--d-ribofuranosyladenine - [9R]Z 9--d-ribofuranosyl-zeatin - BA 6-benzyladenine - DHZ dihydrozeatin - ES⁺ LC-MS/MS HPLC coupled Electrospray Tandem Mass Spectrometry - f.m. fresh mass - mT 6-(3-hydroxybenzyl)adenine - IMA imazalil - iP isopentenyladenine - NAA 1-naphthalene acetic acid - NFT Nutrient Film Technique - (OG)[9R]DHZ O--glucopyranosyl-9--d-ribofuranosyl-dihydrozeatin - (OG)[9R]Z O--d-glucopyranosyl-9--d-ribofuranosyl-zeatin - (OG)DHZ O--d-glucopyranosyl-dihydrozeatin - (OG)Z O--d-glucopyranosyl-zeatin - PAR Photosynthetic Active Radiation - PBZ paclobutrazol - PRO prochloraz - TDZ thidiazuron - TRI triflurnizole - Z zeatin     

Different ζ globin gene deletions among Black Americans

Summary Four types of chromosomes with a deletion between the human embryonic and globin genes were identified among 2.8% of 321 Black Americans from Georgia. Two deletions of approximately 11 kb which differed by about 300 bp occurred on chromosomes with or without a polymorphic Xba I site 5 to the globin gene [(X⁺) or (X^-)]. The deletions are identifiable in Xba I digests of genomic DNA using an or a globin gene probe which yield fragments of 23 kb from (X⁺)–^* chromosomes or 27 kb from (X^–)–^* chromosomes. Digestion with other enzymes and probing with both and probes gave fragments typical of the two globin gene deletions previously identified in Polynesians. Among Black Americans, these globin gene deletions have been found in combination with globin gene deletions in trans but not in cis. Homozygotes have not been found. Hematologic data on carriers of the globin gene deletions in association with Hb AS, SS, and SC suggest that these deletions have no effect on the function of the adult globin genes.     

Ornithine decarboxylase prevents tumor necrosis factor alpha-induced apoptosis by decreasing intracellular reactive oxygen species

Ornithine decarboxylase (ODC) plays an essential role in various biological functions, including cell proliferation, differentiation and cell death. However, how it prevents the cell apoptotic mechanism is still unclear. Previous studies have demonstrated that decreasing the activity of ODC by difluoromethylornithine (DFMO), an irreversible inhibitor of ODC, causes the accumulation of intracellular reactive oxygen species (ROS) and cell arrest, thus inducing cell death. These findings might indicate how ODC exerts anti-oxidative and anti-apoptotic effects. In our study, tumor necrosis factor alpha (TNF-) induced apoptosis in HL-60 and Jurkat T cells. The kinetic studies revealed that the TNF- -induced apoptotic process included intracellular ROS generation (as early as 1 h after treatment), the activation of caspase 8 (3 h), the cleavage of Bid (3 h) and the disruption of mitochondrial membrane potential ( _m) (6 h). Furthermore, ROS scavengers, such as glutathione (GSH) and catalase, maintained _m and prevented apoptosis upon treatment. Putrescine and overexpression of ODC had similar effects as ROS scavengers in decreasing intracellular ROS and preventing the disruption of _m and apoptosis. Inhibition of ODC by DFMO in HL-60 cells only could increase ROS generation, but did not disrupt _m or induce apoptosis. However, DFMO enhanced the accumulation of ROS, disruption of _m and apoptosis when cells were treated with TNF- . ODC overexpression avoided the decline of Bcl-2, prevented cytochrome c release from mitochondria and inhibited the activation of caspase 8, 9 and 3. Overexpression of Bcl-2 maintained _m and prevented apoptosis, but could not reduce ROS until four hours after TNF- treatment. According to these data, we suggest that TNF- induces apoptosis mainly by a ROS-dependent, mitochondria-mediated pathway. Furthermore, ODC prevents TNF- -induced apoptosis by decreasing intracellular ROS to avoid Bcl-2 decline, maintain _m, prevent cytochrome c release and deactivate the caspase cascade pathway.