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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 53 (1989), S. 287-296 
    ISSN: 1570-7458
    Schlagwort(e): European corn borer ; Ostrinia nubilalis ; maize ; water ; drought ; stress ; development ; models ; phytotron ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Des plants de maïs se développent dans un phytotron dans 4 conditions d'humidité du sol (de la saturation à la dessication) et à 3 températures constantes (20°, 25° & 30°C). Chaque pied est contaminé au moment de l'émission du pollen, par une ooplaque d'O. nubilalis Hübn. (ECB) de race européenne E. L'installation, la colonisation et le développement des chenilles sont notés lors de 12 périodes de prélèvements destructifs (4 par température). La vitesse de développement d'O. nubilalis est affectée par la température, main non par l'humidité du sol. Les 4 niveaux d'humidité du sol n'ont aucun effet sur la teneur en eau des tiges de maïs. En fait, les feuilles de maïs présentent une senescence précoce lorsqu'il y a déficit en eau dans le sol. La teneur en eau du sol agit sur l'installation, sur la distribution verticale, la dispersion et le lieu d'alimentation des chenilles; mais ces effets sont légers et ne modifient pas la vitesse de développement. L'environnement larvaire dans la tige de maïs est efficacement isolé des variations externes par l'aptitude de la plante à maintenir la teneur en eau des tiges relativement élevée et stable. Ainsi, des changements importants au niveau du sol n'ont pratiquement pas d'effets sur le développement d'O. nubilalis, malgré les conséquences brutales pour la plante. Cette étude montre que la vitesse de développement d'O. nubilalis est relativement insensible aux modifications de la teneur en eau du sol ainsi qu'aux effets de ce stress de sécheresse sévère sur le pied de maïs. La discussion porte sur l'importance de ces résultats pour la modélisation de la dynamique de l'insecte, la physiologie de la culture et les interactions entre insecte et plante.
    Notizen: Abstract Maize plants were grown under four moisture regimes (wet to extreme deficit) and three constant temperatures (20°, 25° & 30°C) in a phytotron. Each plant was infested with one E-race European corn borer [Ostrinia nubilalis (Hubn.)] (ECB) egg mass at pollen shed. ECB development, location, and establishment were recorded over the course of 12 destructive sample dates (4/temperature). ECB developmental rates were not significantly affected by soil moisture treatments, but were significantly affected by temperature. In spite of successful establishment of four distinctly different soil moisture regimes, the maize stalk tissue water levels were not significantly different among soil water treatments. Instead, the maize plants exhibited accelerated leaf senescence in response to the water deficit conditions. Among the soil water treatments, differences were found in larval establishment, vertical distribution and dispersion, and feeding site selection; however, those effects were slight and could not explain the similarity in ECB developmental rates observed in these treatments. In maize, the larval environment within the stalk was effectively insulated from changes in the external environment by the plant's ability to maintain a relatively high and stable stalk tissue water content. Thus, large changes to the soil environment had essentially no effect on ECB development, though drastic consequences for the plant. This study indicates that ECB rates of development are relatively insensitive to changes in the soil water environment as well as the associated changes in the maize plant that accompany severe drought stress. The significance of these findings to insect modelling, crop physiology, and insect-crop interactions is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of insect behavior 2 (1989), S. 849-852 
    ISSN: 1572-8889
    Schlagwort(e): alternative mating tactics ; temperature ; Stictia heros ; Sphecidae ; Costa Rica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 48 (1988), S. 73-84 
    ISSN: 1570-7458
    Schlagwort(e): Liriomyza trifolii ; Agromyzidae ; Diptera ; temperature ; thresholds ; life history ; feeding ; intrinsic rate of increase ; tomato ; host-plant suitability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé La vitesse de développement, la mortalité, l'alimentation, la fécondité et la longévité de L. trifolii (Burgess) élevés sur plants de tomates du cultivar ‘Moneydor’ ont été examinées au laboratoire sous 3 températures constantes (15°C, 20°C et 25°C) et une thermopériode (16/22°C, moyenne 19,5°C). Les taux de développement et les seuils de chaque stade ont été déterminés à partir des droites de régressions. Aucune corrélation n'a été mise en évidence entre ces variables biologiques et la taille des pupes. De plus, certaines données sur la biologie de L. trifolii sont fournies et discutées. Le taux intrinsèque d'accroissement, rm a varié de-0,0023 oeuf viable/femelle/jour à 15°C à 0,1254 oeuf viable/femelle/jour à 25°C et la reproduction nette de 1 oeuf femelle viable/femelle à 15°C à 26 oeufs femelles viables/femelle à 25°C. La durée d'une génération a varié de 48 jours à 15°C à 24 j à 25°C. 90% de la ponte a eu lieu dans les 115 premiers degrés jours de la vie imaginale à 20 et 25°C. La fécondité et la longévité étaient fortement liées au nombre de piqûres nutritionnelles. Ces résultats montrent que la tomate est un hôte convenable permettant aux populations de L. trifolii de se développer lorsque la température est supérieure à 16°C.
    Notizen: Abstract The effects of three constant (15°C, 20°C and 25°C) and one alternating (16–22°C, mean 19.5°C) temperatures on development, mortality, feeding, fecundity and longevity of Liriomyza trifolii (Burgess) on tomato plants cv. ‘Moneydor’ were examined in the laboratory. Development rates and thresholds for each instar were estimated by means of linear regression. No correlation was found between life history variables and pupal length. Further, data on the biology of L. trifolii are given and discussed. The intrinsic rate of increase, rm, varied from-0.0023 viable female eggs/⧫/day at 15°C to 0.1254 eggs/⧫/day at 25°C and net reproduction from one viable female egg/⧫ at 15°C to 26 eggs/⧫ at 20°C. Generation time varied from 48 days at 15°C to 24 days at 25°C. Ninety % oviposition occurred within the first 115 degree-days of adult life at both 20°C and 25°C. Fecundity and longevity were highly correlated with the number of feeding punctures. The data indicate that tomato is a suitable host plant allowing populations of L. trifolii to increase if temperatures are above 16°C.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 45 (1989), S. 171-173 
    ISSN: 1420-9071
    Schlagwort(e): Estrogen receptor ; homogenization ; temperature ; nucleus ; uterus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Homogenization of rat uterus at elevated temperatures results in an increased nuclear localization of unoccupied estrogen receptor. This is a nonlinear effect which is accounted for by an increased population of KCl-resistant nuclear binding sites at the elevated homogenization temperatures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 45 (1989), S. 349-351 
    ISSN: 1420-9071
    Schlagwort(e): Spermatogenesis ; temperature ; brain ; hibernation ; Helix aspersa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ablation of the brain from hibernatingHelix aspersa maintained at 25°C causes a significant increase in the proliferation of male cells in the gonad, whereas the ablation of the optic tentacles has no effect. The brain, therefore, produces a factor which specifically inhibits the multiplication of spermatogonia and spermatocytes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 46 (1988), S. 19-28 
    ISSN: 1570-7458
    Schlagwort(e): Hymenoptera ; Encyrtidae ; parasitoids ; Pseudococcidae ; mealybugs ; Anagyrus pseudococci ; Leptomastix dactylopii ; Leptomastidea abnormis ; temperature ; predicting development ; thresholds ; temperate glasshouses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Les vitesses de développement de 3 parasitoïdes de cochenilles ont été étudiées dans les conditions de température de serre, avec thermopériode ou en température constante. En conditions constantes, la vitesse augmente jusqu'à 35°C, mais est létale à 40°C. Avec thermopériode, une thermophase de 40°C peut être tolérée pendant 12 heures. Les vitesses de développement sous thermopériodes pourraient être calculées à partir des données obtenues en conditions constantes, modifiées en fonction des durées respectives des cryophases et thermophases. Une méthode originale est présentée pour obtenir les seuils inférieurs de développement, en utilisant des thermopériodes, et pour calculer les vitesses de développement à températures élevées. Une méthode de régression polynomiale, non vérifiée préalablement, a été utilisée pour prévoir les durées moyennes des développements sous serre. Ces estimations sont beaucoup plus sûres que les prédictions basées sur le concept de degré-jour (Do), lorsque les températures extrêmes durent longtemps, mais en serre chaude elles ne présentent aucune différence significative. De plus, une méthode d'évaluation des 95% d'émergences, a donné de bonnes estimations des premières et dermières émergences en conditions périodiques.
    Notizen: Abstract Developmental rates of three encyrtid mealybug parasitoids were examined under constant, cycling and glasshouse temperatures. Under constant conditions the rate of development increased with rising temperature up to 35°C, but a constant 40°C was lethal. Under cycling conditions, 12 h periods at 40°C could be tolerated. Developmental rates under cycling conditions could be calculated from constant temperature data, by incrementing development on an h/h basis. A new technique was developed to determine the lower thresholds for development, using cycling regimes and to calculate the rates of development over short periods at high temperature. A previously untested polynomial regression technique was used to predict mean developmental periods under glasshouse conditions. These predictions were considerably more accurate than day-degree (Do) predictions when substantial periods at extreme temperatures were involved, but not significantly different from day-degree predictions under ‘hot-house’ conditions. In addition a method was developed to calculate a 95% range for emergence, which gave consistently good estimates of first and last eclosion observed under fluctuating conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 47 (1988), S. 173-182 
    ISSN: 1570-7458
    Schlagwort(e): Bembidion lampros ; Pterostichus cupreus ; Carabidae ; Coleoptera ; behaviour ; temperature ; searching ; consumption ; cereal aphid ; Rhopalosiphum padi ; prey ; density ; barley
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Les taux maximum de consommation de R. padi L. à différentes températures ont été déterminés au laboratoire chez deux carabes, B. lampros Herbstet P. cupreus L. La consommation moyenne a augmenté avec la température chez les deux espèces, B. lampros consommant un maximum de 15,9 larves des stades 1 à 3 et 9,1 pucerons adultes aptères, à 25°C. P. cupreus a été particulièrement vorace et a consommé 125,3 adultes aptères par jour à 20°C. Le comportement des deux espèces a été observé en filmant en vidéo des carabes à jeun, maintenus à différentes températures constantes, dans des enceintes semées en orge de printemps. Des éléments du comportement, communs aux deux espèces, ont été définis: 1) immabilité, 2) marche et course, 3) recherche, 4) affrontement. P. cupreus a été plus actif à toutes les températures, B. lamprosa été inactif au-dessous de 10°C. La part de temps consacrée à la recherche, le nombre de plantes prospectées, et la vitesse ont augmenté avec la température chez les deux espèces. Dans des enceintes similaires colonisées par R. padi, P. cupreus a significativement augmenté le temps consacré à la recherche dans les enceintes, parallèlement à l'augmentation de la densité des pucerons. Après la découverte d'une colonie de pucerons, P. cupreus escalade et prospecte la plante et ses voisines immédiates; tandis que les plantes des enceintes sans pucerons sont rarement escaladées. B. lampros n'a pas été observé escaladant des plantes d'enceintes avec ou sans pucerons, et il n'a pas accru son temps de prospection en fonction de la densité de pucerons. Les quelques B. lampros qui ont capturé des pucerons l'ont fait lorsque ceux-ci marchaient sur la surface du sol. La discussion a porté sur l'efficacité relative des deux carabes comme prédateurs de R. padi, et les résultats ont été comparés à ceux d'études du même type, menées ailleurs, avec des prédateurs de Sitobion avenae sur blé d'hiver.
    Notizen: Abstract Maximum consumption rates were determined for two carabids, Bembidion lampros Herbst. and Pterostichus cupreus L., feeding on the cereal aphid Rhopalosiphum padi L. at different temperatures in the laboratory. Mean daily consumption increased with increasing temperature for both species, B. lampros consuming a maximum of 16 1–3 instar nymphs and 9 apterous adult aphids at 25°C. P. cupreus was particularly voracious and consumed 125 apterous adult R. padi per day at 20°C. The behaviour of both species was analysed by video filming starved beetles, maintained at different constant temperatures, in arenas sown with spring barley. The behavioural components (1) still; (2) run/walk; (3) search and (4) confrontation were identified and were common to both species. P. cupreus was more active over the temperature range tested; B. lampros was inactive under 10°C. The proportion of time spent searching, number of plants searched, and velocity increased with increasing temperature for both species. When observed in similar arenas seeded with R. padi colonies, individuals of P. cupreus significantly increased their time spent searching in arenas with increasing aphid density. Following discovery of an aphid colony, individuals climbed and searched the host plant and its nearest neighbours. Plants in aphid free arenas were rarely climbed. B. lampros was not observed climbing in either aphid free arenas or in arenas with increasing aphid densities, and did not significantly increase its time spent searching in response to increased prey density. The few B. lampros that found aphids caught them walking on the soil surface. The relative efficiences of these two carabids as predators of R. padi are discussed, and the results are compared with similar studies elsewhere with predators of Sitobion avenae on winter wheat.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1570-7458
    Schlagwort(e): Coleoptera ; Cerambycidae ; Morimus funereus ; development ; laboratory conditions ; food quality ; temperature ; season
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé L'étude a porté sur les effets d'une température constante (23 °C), de la qualité de l'aliment,-B = aliment naturel, c'est-à-dire de l'écorce de chêne pulvérisée; B+C = aliment naturel enrichi avec de la poudre de biscuits sucrés-, et de la saison sur le développement larvaire de M. funereus L. La température de 23 °C a été défavorable aux larves récoltées en septembre dans des souches de chênes et élevées sur aliment B: les larves étaient mortes en 30 jours. Avec aliment B+C, l'effet défavorable a été neutralisé et le poids des larves augmenté de 543%, 897% et 1179% en 1, 2 et 3 mois. Des larves néonates d'été ou d'hiver se sont bien développées sur B+C, mais toutes les larves d'hiver étaient mortes sur B en 40 j. Des larves de mêmes parents, écloses à différentes époques de l'année, ont présenté des différences saisonnières du taux de survie et de la vitesse de développement lors de leur élevage à 23 °C sur B+C. Le développement le plus rapide et la meilleure survie ont été obtenus avec des larves écloses au début ou au milieu de l'été; tandis que le développement le plus lent et la plus mauvaise survie ont été obtenus avec les larves écloses à la fin de l'été. Les changements saisonniers synchrones des adultes et de leurs descendants, exprimés à différents niveaux d'organisation biologique, suggèrent l'existence d'un rythme annuel endogène qui dépend de l'expression de différents gènes au cours du cycle annuel.
    Notizen: Abstract The effects of constant temperature (23 °C), food quality (B, natural diet i.e. powdered oak bark; B+C, natural diet enriched with powdered sweet crackers) and season on larval development of the cerambycid Morimus funereus L. were studied. The temperature of 23 °C exerted an unfavourable effect on larvae collected from oak stumps in September and bred on B; i.e. the larvae died within 30 days. When the larvae consumed B+C the unfavourable effect of temperature was abolished and the larvae increased their weight by 543%, 897% and 1179% in 1, 2 and 3 months, respectively. Newly hatched summerand winter-larvae developed successfully on B+C, while all the winter-larvae died within 40 days on B. Larvae of an identical parentage hatched in different phases of the annual cycle and showed seasonal differences in the rate of development and survival when reared on B+C at 23 °C. The fastest development and the highest survival rate were observed in larvae which emerged in early- and midsummer, whereas the slowest development and the lowest survival rate were in those hatched in late summer. The synchronized seasonal changes of adults and their offspring, as expressed at different levels of biological organization, suggest the existence of an endogenous annual rhythm which is dependent upon the expression of different genes in the course of the annual cycle.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 52 (1989), S. 185-188 
    ISSN: 1570-7458
    Schlagwort(e): Heteroptera ; Dolycoris baccarum ; S. Norwegian population ; adult hibernal diapause ; diapause completion ; diapause activation ; diapause induction ; diapause prevention ; photoperiod ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1570-7458
    Schlagwort(e): Developmental rates ; temperature ; parasitoid ; mealybug ; Hymenoptera ; Encyrtidae ; Epidinocarsis diversicornis ; Acerophagus coccois ; Homoptera ; Pseudococcidae ; Phenacoccus herreni ; cassava ; yucca
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Les vitesses de développement des oeufs et de tous les stades larvaires mâles et femelles de P. herreni Cox & Williams ont été déterminées à 18°, 20°, 22°, 25°, 30° et 35°C. La longévité des adultes mâles et femelles a été déterminée. Les vitesses de développement de la ponte à la formation du cocon et de celleci à l'émergence de E. diversicornis Howard, encyrtide parasite de P. herreni ont été déterminées à 18°, 20°, 25° et 30°C. Il en a été de même pour un second encyrtide parasite A. coccois Smith à 20°, 25° et 30°C. Les équations polynomiales des derniers carrés dérivés et les équations logistiques ont été ajustées pour chaque lot de données (à l'exception de A. coccois) de façon à ce qu'elles aient pu être interpolées pour analyser l'impact de ces parasites sur la dynamique de population de P. herreni. Les résultats de cette analyse sont présentés à part.
    Notizen: Abstract Developmental rates for Phenacoccus herreni Cox & Williams were determined at 18°, 20°, 22°, 25°, 30° and 35°C for the egg, all juvenile male and all juvenile female stadia. Longevity was determined for adult females and adult males. Developmental rates for the P. herreni parasitoid Epidinocarsis diversicornis (Howard) were determined at 18°, 20°, 25° and 30°C for the oviposition-to-mummy-formation period and the mummy-formation-to-adult-eclosion period. Developmental rates were determined for the P. herreni parasitoid Acerophagus coccois Smith for the same two life stages at 20°, 25° and 30°C. Least-squares-derived polynomial equations or logistic equations were fitted to each data set (except for A. coccois) so that rates could be interpolated for temperatures between observed points for use in an analysis of the impact of these parasitoids on population dynamics of P. herreni. Results of this analysis are presented separately.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Entomologia experimentalis et applicata 50 (1989), S. 185-193 
    ISSN: 1570-7458
    Schlagwort(e): temperature ; development ; simulation ; phenology ; budmoth ; Zeiraphera canadensis ; Tortricidae ; degree-days
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé La diapause des oeufs de Zeiraphera canadensis Mutuura et Freeman (Lepidoptera: Tortricidae) a été complétée après 15 semaines d'élevage à 0,5°C. A ce stade de leur développement, une température supérieure à 30°C leur est létale. Les relations entre la température et le développement des larves sur l'épinette blanche, Picea glauca (Moench) Voss, et des pupes ont été observées au laboratoire. Les temps de développement les plus courts ont été observés à 28°C. Les larves sont tolérantes à la chaleur et se développent à 32 C, une température qui est létale aux pupes. II y a peu de variabilité des taux de développement de tous les stades immatures. Ceci explique le haut degré de synchronie observé au sein de populations de cet insecte. Un modèle simulant la phénologie a été mis au point et calibré pour prédire la fréquence des divers stades du cycle vital sous des conditions de terrain. La processus de calibration a révélé que la température dans le microhabitat des oeufs est très semblable à celle de l'air, mais que les larves, retrouvées sous l'enveloppe des bourgeons, sont exposées à des températures pouvant excéder celle-ci de plusieurs degrés. Pour des fins de planification du synchronisme entre le développement de l'insecte et des programmes de suivi et de lutte, le nombre de degré-jours nécessaires pour atteindre 10% d'éclosion des oeufs ou 75% d'émergence des adultes ont été estimés à partir d'une température seuil de 4,4°C.
    Notizen: Abstract Diapause requirements of eggs of Zeiraphera canadensis Mutuura and Freeman (Lepidoptera: Tortricidae) are satisfied by 15 weeks of storage at 0.5°C. Temperatures above 30°C are lethal for this life stage. Temperature-dependent development of larvae fed on white spruce, Picea glauca (Moench) Voss, and of pupae was observed under laboratory conditions. The shortest development times were observed at 28°C. Larvae are tolerant to heat, and developed at 32°C, a lethal temperature for pupae. There was little variation of development rates in all stages of the life cycle, explaining the high degree of phenological synchrony reported in populations of this species. A phenological model was developed and calibrated to simulate the relative abundance of the various immature stages under field conditions. The calibration process suggested that temperature in the microhabitat of eggs may be very close to air temperature, but that temperatures under bud caps where larvae are feeding may rise several degrees above air temperature. For the purposes of planning the timing of survey and control practices, degree-day requirements for 10% egg hatch and 75% adult emergence were estimated based on a 4.4°C threshold temperature.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    ISSN: 1432-0789
    Schlagwort(e): Wheat ; Paddy straw compost ; N and P enrichment ; Rock phosphate ; Pyrite ; Triticum aestivum ; Nutrient uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 8 (1989), S. 356-368 
    ISSN: 1432-0789
    Schlagwort(e): Plant-root associations ; Azospirillum spp ; Rhizosphere ; Nitrogen fixation ; Acetylene reduction assay (ARA) ; Phytohormones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Bacteria of the genus Azospirillum are extensively studied for their plant-growth promoting effect following inoculation. Physiological and biochemical studies of these diazotrophic bacteria are now benefiting from recent breakthroughs in the development of genetic tools for Azospirilum. Moreover, the identification and cloning of Azospirillum genes involved in N2 fixation, plant interaction, and phytohormone production have given new life to many research projects on Azospirillum. The finding that Azospirillum genes can complement specific mutations in other intensively studied rhizosphere bacteria like Rhizobia will certainly trigger the exploration of new areas in rhizosphere biology. Therefore a review of the Azospirillum-plant interactions is particularly timely.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 6 (1988), S. 39-44 
    ISSN: 1432-0789
    Schlagwort(e): Alnus ; Energy forestry ; Frankia ; Meadow soil ; Nitrogen fixation ; Nodulation ; Peat soil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Use of the N2-fixing grey alder, Alnus incana (L.) Moench, as a short-rotation crop for energy production is currently being explored. To evaluate the need for inoculation of alders, the distribution of infective propagules of Frankia in the soil at potential sites for alder plantations was examined. Uninoculated grey alder seedlings were grown in three types of soil. Frequent nodulation was found in a meadow soil which had been free from actinorhizal plants for nearly 60 years, but the alder seedlings failed to nodulate in peat soil from two different bog sites. One of these bogs had been exploited for peat and the surface layer of the peat had been removed, so that the soil samples were taken from deep layers of the peat. At the other site, an area of cultivated peat, there were no infective propagules of Frankia in plots without alders; the infective Frankia was present in plots only where it had been introduced by inoculated alders. There was no detectable air-borne dispersal of Frankia. Instead, water movement might account for the dispersal of Frankia in peat. Although the apparent absence of Frankia in these peat soils necessitates inoculation of alder seedlings before planting out, this makes it possible to introduce and maintain Frankia strains with selected beneficial characteristics, since there is no competition from an indigenous Frankia flora.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1432-0789
    Schlagwort(e): Nodule damage ; Rivellia angulata ; Nitrogen fixation ; Cajanus cajan ; Pigeonpea ; Vertisol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Damage caused by Rivellia angulata larvae to pigeonpea root nodules at the ICRISAT center in India was greater in the crop grown on Vertisols (up to 86%) compared to that on Alfisols (20%). Attempts to quantify the field effects of nodule damage on growth and yield of pigeonpea in a Vertisol, involving many heavy applications of soil insecticides (aldrin and hexachlorocyclohexane) failed because the insecticides did not control the pest and adversely affected the growth of the pigeonpea and the subsequent crop of sorghum (Sorgorum bicolor L. Moench). The impact of nodule damage on pigeonpea growth, yield and nutrient uptake was successfully studied in greenhouse-grown plants at three N levels. In this pot study, artificial inoculation with Rivellia sp. led to substantial nodule damage (70%). The results of this damage were a significant overall reduction in nodule dry weight (46%), acetylene reduction activity (31%), total leaf area (36%), chlorophyll content of leaves (39%) and shoot dry weight (23%) 68 days after sowing. At maturity, Rivellia sp. infestation caused significant reductions in top dry weight (22%), root and nodule dry weight (27%), seed dry weight (14%), and total N (29%) and P uptake (19%). The problems and prospects of manipulating nodule damage so as to reduce N losses in pigeonpea are discussed.
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 7 (1989), S. 113-119 
    ISSN: 1432-0789
    Schlagwort(e): Vesicular-arbuscular mycorrhiza ; Herbicides ; Wheat ; Glomus spp. ; Spore germination ; Root infection ; Triticum aestivum L. ; Bifenox ; Mecoprop ; Difenzoquat methyl sulphate ; Chlortoluron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary We studied the effects of field application rates of four herbicides (Avenge, Ceridor, Dicurane, and Harrier) on spore germination and infection of wheat roots by three species of Glomus grown under conditions of low P availability. Low concentrations of Ceridor (bifenox, mecoprop) and Harrier (mecoprop, ioxynil, clopyralid) inhibited spore germination while higher concentrations were stimulatory. Avenge (difenzoquat methyl sulphate) prevented spore germination completely, while Dicurane (chlortoluron) had no effect. The herbicide applications had no significant effect on the infection rates of any of the three fungi except Harrier on G. geosporum. The herbicide treatments did, however, affect plant growth and ear yields. Ceridor and Harrier increased ear yields, while Dicurane showed marked phytotoxic effects.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1432-0789
    Schlagwort(e): Dentrification ; Immobilization ; Tillage ; N leaching ; Wheat ; Wetland rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A field study was undertaken to examine the effects of various management strategies on wheat (Triticum aestivum L.) performance and N cycling in an intensively cropped soil. Microplots receiving 100 kg N ha−1 as15NH4 + 15NO3 − at sowing, tillering or stem elongation were compared with unfertilized microplots. Stubble from the previous rice crop was either incorporated, burnt without tillage, burnt then tilled or retained on the surface of untilled soil. Wheat grain yield ranged from 1.5 to 5.1 t ha− and was closely related to N uptake. Plant accumulation of soil N averaged 36 kg N ha−1 (LSD 5% = 10) on stubble-incorporation plots and 54 kg N ha−1 on stubble-retention plots. Fertilizer N accumulation averaged 18 kg N ha−1 (LSD 51% = 6) on stubble-incorporation plots and 50 kg N ha−1 on stubble-retention plots. Tillage had little effect on burnt plots. Delaying N application from sowing until stem elongation increased average fertilizer N uptake from 26 to 39 kg N ha−1 (LSD 5% = 6), but reduced soil N uptake from 50 to 37 kg N ha− (LSD 5% = 10). Immobilization and leaching did not vary greatly between treatments and approximately one-third of the fertilizer was immobilized. Less than 1% of the fertilizer was found below a depth of 300 mm. Incorporating 9 t ha−1 of rice stubble 13 days before wheat sowing reduced net apparent mineralization of native soil N from 37 to 3 kg ha−1 between tillering and maturity. It also increased apparent denitrification of fertilizer N from an average 34 to 53 kg N ha−1 (LSD 5% = 6). N loss occurred over several months, suggesting that denitrification was maintained by continued release of metabolizable carbohydrate from the decaying rice stubble. The results demonstrate that no-till systems increase crop yield and use of both fertilizer and soil N in intensive rice-based rotations.
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 7 (1988), S. 67-70 
    ISSN: 1432-0789
    Schlagwort(e): Root activity ; Soil C mineralization ; 14C-labelled plant material ; Decomposition stages ; Wheat ; Triticum aestivum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the roots removed from the soil, and a new crop was started. Thus, the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. The aim of the experiment was to study the effects of active roots on C-mineralization rates during different stages of decomposition and during long-term incubation. During the first 200 days, corresponding to the active decomposition stages, the roots weakly reduced 14C mineralization. With a lower level of decomposition, when more than 60% of the initial 14C was mineralized and when the available nutrients were markedly exhausted by plant uptake, the roots stimulated 14C mineralization.[/ p]
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 7 (1988), S. 71-78 
    ISSN: 1432-0789
    Schlagwort(e): Root activity ; Rhizosphere ; C metabolism ; Microbial biomass ; Microbial activity ; Wheat ; Triticum aestivum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the old roots removed from the soil, so that the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. During the initial stages of high microbial activity, due to decomposition of the labile compounds, the size of the total microbial biomass was comparable for both treatments, and the metabolic quotient (qCO2-C = mg CO2-C·mg−1 Biomass C·h−1) was increased by the plants. During the subsequent low-activity decomposition stages, after the labile compounds had been progressively mineralized, the biomass was multiplied by a factor of 2–4 in the presence of plants compared to the bare soils. Nevertheless, qCO2-C tended to reach similar low values with both treatments. The 14C-labelled biomass was reduced by the presence of roots and qCO2-14C was increased. The significance of these results obtained from a model experiment is discussed in terms of (1) the variation in the substrate originating from the roots and controlled by the plant physiology, (2) nutrient availability for plants and microorganisms, (3) soil biotic capacities and (4) increased microbial turnover rates induced by the roots.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 7 (1989), S. 269-274 
    ISSN: 1432-0789
    Schlagwort(e): Nitrogen fixation ; Frankia-Ceanothus spp. association ; Acetylene reduction assay (ARA) ; Microsymbiont population ; Nodules ; Actinomycetes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Wildland shrub improvement is needed for sound range and disturbed land revegetation practice. The possibility of selecting superior N2-fixingFrankia-Ceanothus spp. actinorhizal associations was examined. Greenhouse tests were used to expose various soil-borne microsymbiont andCeanothus sp. population accessions in reciprocal combination. The acetylene reduction rate was used as a measure of N2-fixation capacity. There was no significant interaction between host and microsymbiont regardless of source for all variables measured. The acetylene reduction rate, nodule number and mass, plant biomass, and root: shoot ratio were significantly different among soil sources. The acetylene reduction rate was not significantly different amongCeanothus sp. accessions. Neither was it strongly correlated with other variables. It was concluded that the N2-fixation rate is more a function ofFrankia sp. than the hostCeanothus sp. in actinorhizal associations. It appears possible to select soil sources with superior N2-fixing microsymbiont populations.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 6 (1988), S. 279-281 
    ISSN: 1432-0789
    Schlagwort(e): Sesbania rostrata ; Green manure ; Biofertilizer ; Nitrogen fixation ; Stem nodule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Ratooning and stem cutting were compared with seeding in order to reduce the amount of seeds of Sesbania rostrata for green-manure growth. Both methods increased the biofertilizer yield highly significantly within a 6-week growth period.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 251-266 
    ISSN: 1573-0867
    Schlagwort(e): Zinc ; controlled-release ; diffusion ; pH ; temperature ; phosphate ; clay ; sand ; moisture content
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The emission and movement of zinc from planar arrangements of controlled-release (C.R.) thermoplastic matrix zinc fertilizer formulations was studied in cylindrical diffusion cells packed with a clay or a sand. The influences of a number of soil characteristics known to affect zinc diffusion were also investigated. Zinc emission was initially (over 2 days) very rapid. The rate declined markedly thereafter. Morphologically distinct C.R. zinc formulations released zinc at different rates. Zinc moved appreciably and consistently further in the sand than in the clay. Of the soil characteristics studied, increasing phosphate levels had no effect upon zinc emission or mobility in either soil. Increasing pH in the sand did not affect zinc emission, but decreased zinc mobility. Conversely, in the two soils, increasing temperature stimulated zinc emission, but had little influence on zinc mobility. At higher water contents, zinc release was increased in both soils. However, zinc movement was only increased in the sand.
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Biodegradation 7 (1989), S. 159-193 
    ISSN: 1572-9729
    Schlagwort(e): Brachiopod biogeochemistry ; diagenesis ; secular isotopic variations ; carbon isotopes ; oxygen isotopes ; Sr/Ca ; temperature ; Recent ; Late Paleozoic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Sr/Ca ratios in modern brachiopod shells reflect variations in ambient seawater, whereas their Na contents show no relationship with water depth or habitat. Their Mn and Fe contents are controlled, in part, by leaching of these elements from oxide coatings or the low input/sedimentation rate of detrital material into depositional areas such as Quatsino Sound. For most Carboniferous brachiopods from North America, the Mn and Fe contents are similar to those recorded by their Recent counterparts. The high Mn and Fe contents in the brachiopods from shales suggest several possibilities for these levels. One possibility is the leaching of Mn and Fe from oxide coatings/matrix which was not completely removed in the cleaning process, or the high levels in part reflect unusual depositional conditions (some degree of anoxia) for the local shaly environments. The Sr/Ca ratio of brachiopods and, by inference, complementary seawater, did not vary significantly during the Carboniferous. The Sr/Ca minimum observed in brachiopods of Mississippian age coincides with a dip in the 87Sr/86Sr curve and correlates with the Hercynian orogeny. This is attributed to the cycling of seawater through mid-ocean ridge basalts, and postulated exchange reactions account for variation in the composition of seawater-Ca. The unidirectional trend of heavier δ13C values from the Devonian to the Permian is intricately coupled with the evolution of the terrestrial biomass. In addition to expansion of terrestrial plants, burial of reduced carbon in the form of coal (organic matter) contributed to the observed shift. The start of the Permo-Pennsylvanian glaciation is marked by a negative excursion of the secular carbon trend, which is linked to weathering of reduced carbon and its return to the oceanic reservoir with its oxidized carbon. The oxygen isotope values reflect the unidirectional trend towards higher values of the carbon data with decreasing geologic age. Negative excursions of the trend may be related to extensive weathering of terrestrial and submarine rocks, whereas positive excursions may be related to hydrothermal alteration of submarine rocks and dehydration of oceanic crust during times of active sea-floor spreading. Oxygen-calculated water temperatures of unaltered brachiopod material are unrealistically high for all of the Devonian, and the Chesterian-Meramecian, Desmoinesian-Missourian, and Artinskian Epochs. During these times maximum water temperatures of 42° to 56°C are well above the thermal threshold of protein denaturation. This process, which is lethal to most higher organisms, demands an adjustment in oxygen of -2.5%. for samples older than Missourian, and of -1.250%. for samples spanning the Missourian-Artinskian interval. With these adjustments and salinity considerations made prior to calculations, water temperatures become reasonable for the Late Paleozoic epeiric, tropical seas of North America.
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  • 24
    ISSN: 1420-9136
    Schlagwort(e): Middle atmosphere ; temperature ; neutral and ion composition ; turbulent transfer ; model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Using a numerical model for temperature and neutral and ion composition behaviour at middle atmospheric heights, an analysis has been made of the dependence of atmospheric structural parameters on temperature, solar activity, and on turbulent transfer intensity. For mesospheric heights, an inverse dependence of the nitric oxide density on the temperature has been found. It is thus possible to explain experimentally obtained temperature variations over a cyclc of solar activity at mesospheric and lower thermospheric heights. Numerical simulation results indicate that the temperature in the height range ∼75–120 km depends considerably on both the absolute values of turbulent transfer coefficients and their vertical gradients.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Cellular and molecular life sciences 45 (1989), S. 102-103 
    ISSN: 1420-9071
    Schlagwort(e): Djungarian hamster ; photoperiod ; temperature ; T3 ; T4 ; testosterone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effects of photoperiod, temperature and testosterone treatment on plasma T3 and T4 levels were investigated in the Djungarian hamster. Plasma T3 level was affected by temperature (25°C〈7°C) but not by photoperiod. Plasma T4 level was affected by photoperiod (short day 〈 long day) at 25°C. Administration of testosterone increased plasma T4 level under short photoperiod at 25°C. Thus, higher plasma T4 level under long photoperiod at 25°C might be induced by testosterone.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1432-2048
    Schlagwort(e): Auxin (IAA), production by Rhizobium ; Gibberellin production by Rhizobium ; Mutant (Rhizobium) ; Nitrogen fixation ; Phaseolus (nodulation) ; Rhizobium (mutants) ; Root nodule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod − and fix − mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation. The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Planta 176 (1988), S. 461-471 
    ISSN: 1432-2048
    Schlagwort(e): Carbon dioxide fixation ; Citrulline ; Coralloid roots ; Cycads (nitrogen fixation) ; Nitrogen fixation ; Nitrogen transport ; Nostoc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Freshly detached coralloid roots of several cycad species were found to bleed spontaneously from xylem, permitting identification of products of nitrogen transfer from symbiotic organ to host. Structural features relevant to the export of fixed N were described for Macrozamia riedlei (Fisch. ex Gaud.) Gardn. the principal species studied. Citrulline (Cit), glutamine (Gln) and glutamic acid (Glu), the latter usually in a lesser amount, were the principal translocated solutes in Macrozamia (5 spp.), Encephalartos (4 spp.) and Lepidozamia (1 sp.), while Gln and a smaller amount of Glu, but no Cit were present in xylem sap of Bowenia (1 sp.),and Cycas (2 spp.). Time-course studies of 15N enrichment of the different tissue zones and the xylem sap of 15N2-pulse-fed coralloid roots of M. riedlei showed earlier 15N incorporation into Gln than into Cit, and a subsequent net decline in the 15N of Gln of the coralloid-root tissues, whereas Cit labeling continued to increase in inner cortex and stele and in the xylem sap. Hydrolysis of the 15N-labeled Cit and Gln consistently demonstrated much more intense labeling of the respective carbamyl and amide groups than of the other N-atoms. Coralloid roots of M. riedlei pulse-fed 14CO2 in darkness showed 14C labeling of aspartic acid (Asp) and Cit in all tissue zones and of Cit of xylem bleeding sap. Lateral roots and uninfected apogeotropic roots of M. riedlei and M. moorei also incorporated 14CO2 into Cit. The 14C of Cit was restricted to the carbamyl-C. Comparable 15N2 and CO2-feeding studies on corallid roots of Cycas revoluta showed Gln to be the dominant product of N2 fixation, with Asp and alanine as other major 14C-labeled amino compounds, but a total absence of Cit in labeled or unlabeled form.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 79 (1989), S. 566-568 
    ISSN: 1432-1939
    Schlagwort(e): Carbon dioxide ; Lichen ; Lobaria ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Thalli of Lobaria pulmonaria (L.) Hoffm., a nitrogen-fixing epiphyte common in mesic temperate forests, were collected in a Douglas-fir (Pseudotsuga menziesii Franco) forest near Corvallis, Oregon, and maintained for 20 to 40 days in controlled-environment chambers with atmospheric CO2 concentrations of 374 and 700 μll-1. Nitrogenase activity, which was assayed by the acetylene reduction method, was approximately doubled in the lichen maintained in elevated CO2. Increases in nitrogen fixation by lichens may be an important part of the integrated ecosystem response to rising CO2.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 150 (1988), S. 326-332 
    ISSN: 1432-072X
    Schlagwort(e): Rhizobium leguminosarum ; Plasmids ; Melanin ; Nodulation ; Nitrogen fixation ; Plasmid curing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Rhizobium leguminosarum strain VF39, isolated from nodules of field-grown faba beans in the Federal Republic of Germany, was shown to contain six plasmids ranging in molecular weight from 90 to 400 Md. Hybridisation to nif gene probes, plasmid curing, and mobilisation to other strains of Rhizobium and to Agrobacterium showed that the third largest plasmid, pRleVF39d (220 Md), carried genes for nodulation and nitrogen fixation. This plasmid was incompatible with pRL10JI, the Sym plasmid of R. leguminosarum strain JB300. Of the other plasmids, the two smallest (pRleVF39a and pRleVF39b, 90 and 160 Md respectively) were shown to be self-transmissible at a low frequency. Although melanin production is as yet unreported in strains of R. leguminosarum biovar viceae, strain VF39 produced a dark pigment, which, since it was not produced on minimal media and its production was greatly enhanced by the presence of tyrosine in the media, is probably melanin-like. Derivatives of VF39 cured of pRleVF39a no longer produced this pigment, but regained the ability to produce it when this plasmid was transferred into them. Strains of Agrobacterium tumefaciens, R. meliloti, and some strains of R. leguminosarum carrying pRleVF39a did not produce this pigment, indicating perhaps that some genes elsewhere on the VF39 genome are also involved in pigment production. Plasmid pRleVF39a appeared to be incompatible with the cryptic Rhizobium plasmids pRle336b and pRL8JI (both ca. 100 Md), but was compatible with the R. leguminosarum biovar phaseoli Sym plasmids pRP1JI, pRP2JI and pRph51a, all of which also code for melanin production. The absence of pRleVF39a in cured derivatives of VF39 had no effect on the symbiotic performance or competitive ability of this strain.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 150 (1988), S. 224-229 
    ISSN: 1432-072X
    Schlagwort(e): Vibrio ; V. diazotrophicus ; V. natriegens ; V. pelagius ; V. cincinnatiensis ; Nitrogenase ; Nitrogen fixation ; Oxygen sensitivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Virtually all Vibrio spp. known and available in culture collections and several newly isolated Vibrio sp. were tested for their ability to fix molecular nitrogen, using the acetylene reduction technique, the fixation of the heavy isotope 15N, and by growth on media devoid of combined nitrogen. Among the 27 species tested, four, including V. diazotrophicus, proved to be nitrogenase-positive. The potential of nitrogen fixation was now also discovered in V. natriegens, V. pelagius and V. cincinnatiensis. Among the 9 newly isolated strains, 4 were nitrogenase-positive. These strains were classified as V. diazotrophicus on the basis of DNA homology studies. Nitrogenase was only induced during growth under anaerobic conditions. Dissolved oxygen as low as 1 μM inhibited nitrogenase completely. This inhibition at low oxygen concentration, however, was reversible. 50–100 μM dissolved oxygen inhibited nitrogenase irreversibly.
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  • 31
    ISSN: 1432-072X
    Schlagwort(e): Azorhizobium caulinodans ORS571 ; Hydrogenase ; Nitrogen fixation ; Chemostat cultures ; H2/N2 ratio ; ATP/2e value
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hydrogenase-negative (Hup-) mutants of Azorhizobium caulinodans ORS571 were isolated by means of Tn5 mutagenesis. The colony test used for screening for Hup- strains was based on the absence of reduction of triphenyltetrazolium chloride with hydrogen. Suspensions from cultures of the mutant strains grown under derepressing conditions did not use hydrogen with methylene blue or oxygen as the hydrogen acceptor. The mutants were shown to carry single Tn5 insertions at different locations in the A. caulinodans genome. Molar growth yields (corrected for poly-β-hydroxybutyrate formation) in chemostat cultures of the mutants were similar to those of the wild type. Molar growth yields of the mutants were not increased by passing additional hydrogen through chemostat cultures, which is in agreement with the hydrogenase-negative phenotype of the mutants. H2/N2 ratios (mol H2 formed per mol N2 fixed) were calculated from the hydrogen content of the effluent gas and the N-content of the bacterial dry weight. Low H2/N2 ratios (between 1.2 and 1.9) were found in both energy-limited (oxygen or succinate) cultures and in cultures limited by the supply of an anabolic substrate (Mg2+). ATP/2e values (mol ATP used at the transport of 2e to nitrogen or H+) were calculated from the H2/N2 ratios and the molar growth yields of nitrogen-fixing and ammonia-assimilating cultures. ATP/2e values were between 7 and 11. It was concluded that the calculated ATP/2e values comprise not only 4 mol ATP used at the transport of 2e through nitrogenase but also energy equivalents needed for reversed electron flow from NADH to the low-potential hydrogen donor used by nitrogenase.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 151 (1988), S. 44-48 
    ISSN: 1432-072X
    Schlagwort(e): Vanadium ; Molybdenum ; Methanogenesis ; Nitrogen fixation ; Archaebacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nitrogen fixation of the Methanosarcina barkeri strains “Fusaro” (DSM 804) and “227” (DSM 1538) was found to be dependent on the presence of vanadium or molybdenum whereby molybdenum (added as Na2-molybdate) was preferred to vanadium (added as VCl3). Strain “227” showed less pronounced effects on diazotrophic growth with respect to vanadium and molybdenum. Rhenium (ReCl3) or tungsten (Na2-tungstate) could not replace vanadium or molybdenum. The optimum concentrations were found to be 2μM for vanadium and 5μM for molybdenum (strain “Fusaro”). This Mo optimum of methanogenesis was 10-fold higher with N2 than with NH4Cl as nitrogen source. A vanadium requirement with NH4Cl could not be detected. No interferences were observed if molybdenum and vanadium were added simultaneously under diazotrophic conditions. Growth yields were smallest for strain “227” grown diazotrophically ( $$Y_{CH_3 OH}$$ =0.6g dw/mol in the presence of vanadium and $$Y_{CH_3 OH}$$ =0.9g dw/mol in the presence of molybdenum), obviously higher for strain “Fusaro” grown diazotrophically ( $$Y_{CH_3 OH}$$ =1.15g dw/mol in the presence of V and $$Y_{CH_3 OH}$$ =1.4g dw/mol with Mo) and highest if M. barkeri was grown on NH4Cl as N-source ( $$Y_{CH_3 OH}$$ =3.4g dw/mol with Mo, strain “Fusaro”).
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 151 (1989), S. 445-453 
    ISSN: 1432-072X
    Schlagwort(e): Denitrification ; Growth yield measurements ; Nitrate respiration ; Nitrogen fixation ; Proton translocations in respirations ; Azospirillum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract For Azospirillum brasilense Sp7, the energy transformation efficiencies were measured in anaerobic respirations with either nitrate, nitrite or nitrous oxide as respiratory electron acceptors by determining the maximal molar growth yields and the H+-translocations using the oxidant pulse method. In continuous cultures grown with malate limiting, the maximal molar growth yields (Y s max -values) were essentially the same with O2 or N2O but were 1/3 and 2/3 lower with NO 2 - or NO 3 - , respectively, as respiratory electron acceptors. Both the maximal molar growth yields and the maintenance energy coefficients were surprisingly high when Azospirillum was grown with nitrite as the sole electron acceptor and source for N-assimilation. Growth under N2-fixing conditions drastically reduced the Y s max -values in the N2O and O2-respiring cells. In the H+-translocation measurements, the $$\vec H^ + $$ /oxidant ratios were 5.6 for O2→H2O, 2.5–2.8 for NO 3 - →NO 2 - , 2.2 for NO 2 - →N2O and 3.1 for N2O→N2 respirations when the cells were preincubated with valinomycin and K+. All the values were enhanced when the experiments were performed with valinomycin plus methyltriphenylphosphonium (=TPMP+) cation. The uncoupler carbonyl cyanide-m-chlorophenyl-hydrazone diminished the H+-excretion indicating that this translocation was due to vectorial flow across the membrane. In the absence of any ionophore, nitrate and nitrite respirations were accompanied by a H+-uptake $$(NO_3^ - \to N_2 = - 2.9 \vec H^ + /NO_3^ - and NO_2^ - \to N_2 = - 2.5 \vec H^ + /NO_2^ - )$$ . Any significant H+-translocation could not be detected in N2O- and O2-respirations under these conditions. It is concluded that nitrate reduction proceeds inside the cytoplasmic membrane, whereas nitrite is reduced extramembraneously. The data are not conclusive for the location of nitrous oxide reductase. The maximal molar growth yield determinations and the absence of any H+-uptake in untreated cells indicate a cytoplasmic orientation of the enzyme similar to the terminal cytochrome oxidase of respiration. The low H+-extrusion values for N2O-respiration compared to O2-respiration in cells treated with valinomycin plus TPMP+ are, however, not in accord with such an interpretation.
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  • 34
    ISSN: 1432-072X
    Schlagwort(e): Bradyrhizobium ; Gene cloning ; Heme ; Marker exchange mutagenesis ; Nitrogen fixation ; Respiration ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Random and site-directed Tn5-induced mutagenesis of Bradyrhizobium japonicum yielded two mutations, one in strain 2960 and the other in strain 2606::Tn5-20, which mapped close to each other but in separate genes. The corresponding wild-type genes were cloned, and their approximate location on the cloned DNA was determined. Mutant 2960 was Fix- and formed green nodules on soybean, whereas strain 2606::Tn5-20 had ca. 4% of wild-type Fix activity and formed white nodules. Cytochrome oxidase assays (Nadi tests) showed a negative reaction with both mutants, indicating a functional deficiency of cytochrome c or its terminal oxidase or both. However, the mutants grew well under aerobic conditions on minimal media with different carbon sources. Furthermore, mutant 2960 had a reduced activity in hydrogen uptake, was unable to grow anaerobically with nitrate as the terminal electron acceptor and 2960-infected soybean nodules contained little, if any, functional leghemoglobin. Southern blot analysis showed that a B. japonicum heme biosynthesis mutant [strain LO505: O'Brian MR, Kirshbom PM, Maier RJ (1987) Proc Natl Acad Sci USA 84: 8390–8393] had its mutation close to the Tn5 insertion site of our mutant 2606::Tn5-20. This finding, combined with the observed phenotypes, suggested that the genes affected in mutants 2960 and 2606::Tn5-20 were involved in some steps of heme biosynthesis thus explaining the pleiotropic respiratory deficiencies of the mutants. Similar to strain LO505, the mutant 2606::Tn5-20 (but not 2960) was defective in the activity of protoporphyrinogen IX oxidase which catalyzes the penultimate step in the heme biosynthesis pathway. This suggests that one of the two cloned genes may code for this enzyme.
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 151 (1989), S. 180-182 
    ISSN: 1432-072X
    Schlagwort(e): Klebsiella pneumoniae ; Nitrogen fixation ; nifL ; Regulation ; Oxygen control ; Nitrogen control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A number of in-frame deletions have been constructed in the Klebsiella pneumoniae regulatory gene nifL. The effects of each nifL mutation on NifA-mediated expression from the nifH promoter of K. pneumoniae have then been assessed with respect to both nitrogen and oxygen control. These experiments indicate that, in contrast to the situation with the homologous regulatory proteins NtrB and NtrC, NifA activity is not impaired in the absence of NifL. We conclude that the only function of NifL is to inactivate NifA in response to an increase in the nitrogen or oxygen status of the cell.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Planta 174 (1988), S. 51-58 
    ISSN: 1432-2048
    Schlagwort(e): Bacteroid ; Bradyrhizobium ; Glycine (N2 fixation) ; Nitrate reductase ; Nitrite reductase ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Bacteroids of Bradyrhizobium japonicum strain CB1809, unlike CC705, do not have a high level of constitutive nitrate reductase (NR; EC 1.7.99.4) in the soybean (Glycine max. Merr.) nodule. Ex planta both strains have a high activity of NR when cultured on 5 mM nitrate at 2% O2 (v/v). Nitrite reductase (NiR) was active in cultured cells of bradyrhizobia, but activity with succinate as electron donor was not detected in freshly-isolated bacteroids. A low activity was measured with reduced methyl viologen. When bacteroids of CC705 were incubated with nitrate there was a rapid production of nitrite which resulted in repression of NR. Subsequently when NiR was induced, nitrite was utilized and NR activity recovered. Nitrate reductase was induced in bacteroids of strain CB1809 when they were incubated in-vitro with nitrate or nitrite. Increase in NR activity was prevented by rifampicin (10 μg· ml-1) or chloramphenicol (50 μg·ml-1). Nitrite-reductase activity in bacteroids of strain CB1809 was induced in parallel with NR. When nitrate was supplied to soybeans nodulated with strain CC705, nitrite was detected in nodule extracts prepared in aqueous media and it accumulated during storage (1°C) and on further incubation at 25°C. Nitrite was not detected in nodule extracts prepared in ethanol. Thus nitrite accumulation in nodule tissue appears to occur only after maceration and although bacteroids of some strains of B. japonicum have a high level of a constitutive NR, they do not appear to reduce nitrate in the nodule because this anion does not gain access to the bacteroid zone. Soybeans nodulated with strains CC705 and CB1809 were equally sensitive to nitrate inhibition of N2 fixation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Planta 179 (1989), S. 441-447 
    ISSN: 1432-2048
    Schlagwort(e): Glutamate synthase ; Glutamine synthetase ; Nitrogen fixation ; Phaseolus (glutamate synthase) ; Plastid (glutamate synthase) ; Root nodule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The two isoenzymes of NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14), previously identified in root nodules of Phaseolus vulgaris L., have both been shown to be located in root-nodule plastids. The nodule specific NADH-GOGAT II accounts for the majority of the activity in root nodules, and is present almost exclusively in the central tissue of the nodule. However about 20% of NADH-GOGAT I activity is present in the nodule cortex, at about the same specific activity as this isoenzyme is found in the central tissue. Glutamine synthetase (GS; EC 6.3.1.2) occurs predominantly as the γ polypeptide in the central tissue, whereas in the cortex, the enzyme is represented mainly by the β polypeptide. Over 90% of both GS and NADH-GOGAT activities are located in the central tissue of the nodule and GS activity exceeds NADH-GOGAT activity by about twofold in this region. Using the above information, a model for the subcellular location and stoichiometry of nitrogen metabolism in the central tissue of P. vulgaris root nodules is presented.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell reports 8 (1989), S. 263-266 
    ISSN: 1432-203X
    Schlagwort(e): Wheat ; Maize ; Intergeneric cross-Embryo culture ; Haploid production
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Four Japanese wheat varieties, three crossable and one non-crossable with Hordeum bulbosum, were pollinated with maize pollen of 5 genotypes. By the application of 2,4-dichlorophenoxyacetic acid after pollination, embryos kept developing on wheat plants until 14 days after pollination. The frequency of embryo formation was significantly different among the maize genotypes, varying from 18.0% to 31.9%, but not among the wheat varieties. By bagging spikes with flag leaves the frequency of embryo formation was increased by about 7%. Ten- to twelve-day-old embryos gave higher frequencies of plant formation (83.6%) than 14-day-old embryos(50.0%). All 6 regenerated plants investigated cytologically were found to be haploid. Twelve of the 14 colchicine-treated plants produced florets setting seeds. The overall efficiency of our procedure is considered to be higher than that reported by Laurie and Bennett (1988).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 103 (1988), S. 149-158 
    ISSN: 1432-1424
    Schlagwort(e): H+ pump ; K+ channel ; light ; Nitella ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary At membrane potentials different fromE K, the temperature effect on membrane potential ofNitella consists of two components. One of them changes its sign atE K, the other one does not. This leads to the assignment of these components to changes in the K+ channel and in the H+ pump, respectively. It is shown that the fast time constant (3 to 30 sec) of the temperature effect on the H+ pump measured as a change in membrane potential and that of the temperature effect on the K+ channel measured as a change in resistance (having about twice the value of that of the pump) are sensitive to light intensity. Both time constants measured inNitella become smaller if light intensity increases from 0 to 15 Wm−2. This supports the suggestion of Fisahn and Hansen (J. Exp. Bot. 37:440–460, 1986) that temperature acts on plasmalemma transport via photosynthesis via the same mechanism as light does.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 112 (1989), S. 277-289 
    ISSN: 1432-1424
    Schlagwort(e): myelinated nerve fiber ; gating current ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Asymmetrical displacement currents and Na currents of single myelinated nerve fibers ofXenopus laevis were studied in the temperature range from 5 to 24°C. The time constant of the on-response atE=4 mV,τ on, was strongly temperature dependent, whereas the amount of displaced charge atE=39 mV, Qon, was only slightly temperature dependent. The mean Q10 forτ on -1 was 2.54, the mean Q10 for Qon was 1.07. The time constant of charge immobilization,τ i , atE=4 mV varied significantly (α=0.001) with temperature. The mean Q10 forτ i -1 was 2.71±0.38. The time constants of immobilization of gating charge and of fast inactivation of Na permeability were similar in the temperature range from 6 to 22°C. The Qoff/Qon ratio forE=4 mV pulses of 0.5 msec duration decreased with increasing temperature. The temperature dependence of the time constant of the off-response could not be described by a single Q10 value, since the Q10 depended on the duration of the test pulse. Increasing temperature shifted Qon (E) curves to more negative potentials by 0.51 mVK −1, but shiftedP Na (E) curves andh ∞ (E) curves to more positive potentials by 0.43 and 0.57 mV K−1, respectively.h ∞ (E=−70 mV) increased monotonously with increasing temperature. The present data indicate that considerable entropy changes may occur when the Na channel molecule passes from closed through open to inactivated states.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 101 (1988), S. 67-72 
    ISSN: 1432-1424
    Schlagwort(e): hemolysis ; membrane ; erythrocyte ; pyrexia ; phospholipid ; phase transition ; unilamellar ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Rates of human red blood cell hemolysis were measured as a function of temperature. Three distinct temperature intervals for hemolysis were noted: a) At temperatures equal to or less than 37°C no hemolysis was observed for the duration of the incubation (30 hr). b) For temperatures exceeding 45°C hemolysis rates are rapid and are accompanied by gross changes in cellular morphology. The activation energy for hemolysis is 80 kcal/mole; this value is characteristic of protein denaturation and enzyme inactivation suggesting that these processes contribute to hemolysis at these high temperatures. c) Between 38 and 45°C the energy of activation is 29 kcal/mole, indicating that a fundamentally different process than protein inactivation is responsible for hemolysis at these relatively low temperatures. A mechanism based on the concept of the critical bilayer assembly temperature of cell membranes (N.L. Gershfeld,Biophys. J. 50:457–461, 1986) accounts for hemolysis at these relatively mild temperatures: The unilamellar state of the membrane is stable at 37°C, but is transformed to a multibilayer when the temperature is raised; hemolysis results because formation of the multibilayer requires exposing lipid-free areas of the erythrocyte surface. An analysis of the activation energy for hemolysis is presented that is consistent with the proposed unilamellar-multibilayer transformation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 169-175 
    ISSN: 1432-2242
    Schlagwort(e): Mitochondrial DNA ; Chondriome variability ; In vitro culture ; Plant regeneration ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Plants have been regenerated from short-and long-term in vitro somatic tissue cultures made from immature embryos of the hexaploid wheat cultivar “Chinese Spring”. The mitochondrial genome organization of each regenerated plantlet was studied, after one selfing, by probing Sal I-restricted total DNA with cloned Sal I fragments of wheat mitochondrial DNA derived from a segment of the genome, which displays marked structural changes in response to in vitro culture. Short-term in vitro cultures give rise to regenerated plants whose mitochondrial genome organization is either close to that of the parental cultivar or to that of embryogenic callus cultures, except for a single plant which has an organization resembling that of short-term non-embryogenic cultures. In contrast, all but one of the plants regenerated from long-term cultures exhibited a mitochondrial genome organization similar to that of long-term nonembryogenic cultures. In addition, extra labelled bands were detected in some of the regenerated plants with two of the probes used. These results emphasize the importance of the duration of the in vitro step preceding the regeneration process: the longer it is, the higher the probability is of obtaining mitochondrial DNA variability in regenerated plants. Furthermore, since increasing the duration of the in vitro stetp results in the production of regenerated plants with a mitochondrial genome organization resembling that of non-embryogenic tissue cultures, the question is thus raised as to whether regeneration from long-term cultures is suitable for use in plant breeding.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Aegilops ventricosa ; Powdery mildew resistance ; Biochemical markers ; Addition and transfer lines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The gene encoding a variant of alcohol dehydrogenase, Adh-μ, has been found to be associated with the chromosome of the Mv genome which is present in type 9 wheat/Aegilops ventricosa addition line, to which the genes for protein CM-4 and for a phosphatase variant, Aph-v, had been previously assigned. Transfer line H-93-33, which has 42 chromosomes and has been derived from the cross (Triticum turgidum x Ae. ventricosa) x T. aestivum, carries genes encoding all three biochemical markers. Linkage between these genes has been demonstrated by analysis of individual kernels of the F2 (H-93-33 x T. aestivum cv. “Almatense” H-10-15). A study of the hybrids of line H-93-33 with T. aestivum H-10-15 and with the 4DS ditelosomic line has confirmed that, as suspected, the linkage group corresponds to chromosome 4Mv from Ae. ventricosa. Additionally, it has been found that the previously reported resistance of line H-93-33 to powdery mildew (Erysiphe graminis) is also linked to the biochemical markers; this indicates that either the gene responsible for it is different from that in lines H-93-8 and H-93-35, or that a translocation between two different Mv chromosomes has occurred in line H-93-33.
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 516-520 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Single seed descent (SSD) ; Single plant selection (SPS) ; Bulk population (BP) ; Mechanical mass selection (MMS)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Four methods of generation advance (SPS, SSD, BP and MMS) were compared in F3 and F4 generations. In the F3 generation, the SPS and SSD methods of generation advance proved superior to the BP and MMS methods for grain yield per plant and for at least one of the yield component traits. The F3 SSD population did not differ significantly from the F3 SPS for any of the traits. However, the F3 SSD population retained more range and cv for different traits than with other methods of generation advance. F4 progenies derived from F3 SSD population were significantly superior for grain yield than lines derived from the other three F3 populations. The MMS method of generation advance proved useful for increasing the 1,000-grain weight for which initial selection was made.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 685-688 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Triticale ; Cytoplasmic effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Thirteen wheat-like advanced-generation triticale x wheat derivatives, having tetraploid wheat cytoplasm from triticale, were reciprocally crossed with three improved bread wheats, and the resulting F1s were evaluated for determining the comparative performance of the bread wheat and triticale cytoplasms for different traits. Significant reciprocal differences in the mean performance were observed for days to heading, days to maturity, spikes/plant, flag-leaf area, peduncle length, plant height, spike length, grains/spike, 1,000-grain weight, grain yield and grain protein content, and most of them were in favour of hexaploid wheat cytoplasm. However, this superiority of the hexaploid cytoplasm was not universal for a particular trait, implying that the differences in the performance of the evaluated reciprocal crosses depended not solely on the cytoplasmic background, but also on the interplay of the specific genotype with the cytoplasm.
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 809-814 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Ribosomal DNA ; Tissue culture ; Somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In a previous study we observed extensive Nor region variability in tissue-culture derived plants of only one out of three tested wheat cultivars. This finding prompted us to further question whether or not this variability was invariably caused by in vitro culture. In the present study, the upper halves of spikes from four source plants of the inbred cultivar ‘ND7532’ were removed 12 days after anthesis. The immature embryos from these halves were cultured and regenerated into plants. The lower halves of the same spikes were retained on the plants to obtain mature caryopses. DNA was extracted from seedlings, cut with TaqI endonuclease, run on agarose gels, and the respective Southern blots were probed with the plasmid pTA71 to reveal the Nor region patterns. The sexual progeny of regenerants from three out of four source plants derived from the immature embryos provided Nor region patterns which were exactly identical to the patterns obtained from seedlings which germinated from the caryopses matured on the respective source spikes. The regenerants from the fourth source plant provided variable Nor region patterns. Analyses of the Nor region patterns of 21 individual seedlings germinated from caryopses of this source plant showed that 18 had a three-fragment pattern (consisting of 3.0, 2.7 and 1.9 kb fragments) while three seedlings lacked one (2.7 of 1.9 kb) fragment. Furthermore, the next sexual progeny of the regenerants which had a three-fragment pattern further segregated into three- and two-fragment patterns.These results, in conjunction with previous reports on Nor region variability among tissue-culture derived plants, suggest that this variability is not invariably related to in vitro culture.
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 57-60 
    ISSN: 1432-2242
    Schlagwort(e): Hybrid necrosis ; Wheat ; Immature embryoculture ; Young ear culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Hybrid necrosis in wheat is a barrier to gene transfer in wheat breeding practice. It is based on two complementary genes, Ne1 and Ne2. Recovery mutants (Re1, Re2 and Re3) which can grow to maturity were recovered from immature embryo cultures of necrotic hybrids between T. aestivum and T. durum. Cytological observation demonstrated that Re1 had 34 chromosomes instead of 35. This indicated that one of the chromosomes carrying the Ne genes was lost. Genetic study suggested that for Re1, the lost chromosome was chromosome 5B of the durum parental line. Re mutants are male sterile but can be maintained through a young ear culture method. Re mutants could be successfully pollinated by either parental line and the BC1 progeny is partially fertile. Re mutants were repeatedly induced in about 1% of the regenerated plants from immature embryo culture. This technique provides a practical way to bypass hybrid necrosis.
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 137-142 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Diallel analysis ; Somatic embryogenesis ; Plant regeneration ; In vitro culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Diallel analyses of F1 and reciprocal crosses among five winter wheat lines show that additive, non-additive, and cytoplasmic genetic effects were significant in the genetic control of somatic embryogenesis, shoot, and root induction frequencies as well as in numbers of somatic embryos, shoots, and roots. However, additive genetic effect appears to be most important since, in most cases a larger portion of the cross variation was accounted for by general combining ability. The results suggest that somatic embryogenesis and organ regeneration in winter wheat can be improved through genetic manipulation. Due to the presence of maternal effects, it may be critical to use a suitable genotype as a female parent in a selection program.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 783-787 
    ISSN: 1432-2242
    Schlagwort(e): Tissue culture ; Callus ; Wheat ; Ditelosomics ; Nullisomic-tetrasomics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The ability of immature embryos of wheat (Triticum aestivum L.) to respond to tissue culture has been shown to involve the group 2 chromosomes. The available group 2 ditelosomic and nullisomic-tetrasomic lines of ‘Chinese Spring’ wheat were used to determine the chromosome arm location and chromosome dosage effect associated with the expression of tissue culture response (TCR). Significant differences were found between the aneuploid lines and the euploid control for the expression of both regenerable callus formation and callus growth rate. A model is proposed suggesting that a major TCR gene is located on 2DL and that 2AL and 2BS possess minor TCR genes. Furthermore, a major regulatory gene controlling the expression of TCR genes may be located on chromosome 2BL.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 867-872 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Cytoplasm ; Anther culture ; Microspore embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Anthers were cultured from two sets of seven lines of hexaploid wheat (Triticum aestivum L.) with different cytoplasms, the euplasmic nucleus donors, ‘Siete Cerros 66’ and ‘Penjamo 62’, as well as their six alloplasmic lines derived from wild relative species of the genera Triticum and Aegilops. Significant cytoplasmic and nuclear effects but no cytoplasmic-nuclear interaction were found for embryogenic anther response, with the best performance of ‘Penjamo 62’ in Ae. kotschyi cytoplasm. Plant regeneration was not affected significantly by the cytoplasmic background of the lines cultured. The possible genetic implications of the observed cytoplasmic and nuclear influences on the in vitro haploid induction of wheat are discussed.
    Materialart: Digitale Medien
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  • 51
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Callus ; Regeneration ; Dwarfinggenes ; Rht
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Calli were initiated from immature embryos of 12 lines of hexaploid wheat (Triticum aestivum L. em. Thell). The lines were from 3 varieties — April Bearded, Bersee and Maris Huntsman — isogenic for the reduced height/gibberellic acid insensitivity (Rht) genes — Rht1, Rht2 and Rht3 — and the ‘tall’ (rht) allele. The dwarfing genes had significant effects on the growth and morphogenesis of calli. The genes interacted with the 2,4-D in the medium and the varietal background. Calli of each line were cultured in the presence and absence of 1 mg/l of gibberellic acid (GA), but there was no interaction of the Rht genes with GA in vitro. The effect of the Rht genes is discussed in relation to their effects on cellular hormone metabolism and their involvement in previously described chromosome 4B effects in culture.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 75 (1988), S. 642-650 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; HMW glutenin subunits ; Linkage mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A translocation mapping procedure was used to map the Glu-1 genes, controlling high-molecular-weight (HMW) glutenin subunits on the long arms of group 1 wheat chromosomes, with respect to their centromeres. The Glu-A1 genes on chromosome arm 1AL were linked with the centromere but gave very different map distances (in cM) of 10.2 ± 3.5 and 33.9 ± 5.4 with test-cross and F2 progeny, respectively. The centromere-Glu-B1 and centromere-Glu-D1 map distances were estimated to be 28.1 ± 2.8 and 30.9 ± 2.7, respectively, using test-cross seeds. A telocentric mapping procedure gave a reduced map distance of 22 ± 3.5 for the centromere-Glu-D1 interval. Possible reasons for the differences between the mapping results obtained with test-cross and F2 seeds and with the translocation and telocentric procedures are discussed.
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  • 53
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Anther culture ; Regeneration ability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Marked effects of genotype on wheat anther culture response have been observed. Genetic factors have been recognised to be one of the major contributors to in vitro responses of cultured wheat tissues. In wheat anther culture, embryo induction, plant regeneration and albina/green ratio have been determined to be heritable traits. Using Chinese Spring (CS) monosomic 1D, single chromosome substitution lines of chromosome 5B or chromosome arm 5BL from Chinese Spring into six varieties, and F1 hybrids heterozygous for the 1B chromosome structure (1BL-1BS/1BL-1RS), the anther culture response was studied: genes on CS1D chromosome and 5BL chromosome arm increases the embryo frequency; gene(s) involved in regeneration ability are located on the 1RS chromosome arm; a gene increasing albina frequency is located on Chinese Spring 5B chromosome. Our results support the fact that without gametic selection, a differential development occurred from the particular classes of microspores carrying genes for higher regeneration ability. Moreover, in some crosses, a few genes with major effects were involved in determination of anther culture response.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 75 (1988), S. 286-290 
    ISSN: 1432-2242
    Schlagwort(e): RFLP ; Wheat ; Aegilops ; Rye ; β-Amylase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A β-amylase cDNA clone isolated from barley has been used to locate β-amylase encoding sequences on wheat, rye, and Aegilops umbellulata chromosomes by hybridisation to restriction endonuclease digested DNA obtained from wheat aneuploid and wheat-alien addition lines. Structural genes were identified on homoeologous group 4 and 5 chromosomes, confirming the results of isozyme studies. In addition, a further set of structural genes was found on homoeologous group 2 chromosomes. It is proposed that there are two homoeoallelic series, β-Amy-1 on group 4 or 5 chromosomes, and β-Amy-2 on group 2 chromosomes. Evidence is presented that each locus contains one or two β-amylase structural genes, and it is suggested that the large number of isozymes seen upon IEF are due to post-translational modifications.
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 75 (1988), S. 305-308 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Giemsa/Leishman ; C-banding ; Polymorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chromosomes of tetra- and hexaploid wheat have been individually characterized by Giemsa and/or Leishman C-banding techniques. Appropriate methodological modifications resulted in almost identical staining of chromosomes of tetraploid wheat with Giemsa and Leishman solutions. Additionally comparison of Giemsa banded chromosomes of the A- and B-genome of Triticum turgidum 34 and Triticum aestivum cv ‘Jubilar’ reveals similar or corresponding patterns in all homologous chromosomes with the exception of chromosome 7B. Apart from this intervarietal variation in certain homologous chromosomes of both wheat cultivars, intravarietal polymorphism is verified.
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  • 56
    ISSN: 1432-2242
    Schlagwort(e): Ribosomal DNA ; Restriction fragment length polymorphism ; Anther-derived doubled haploids ; Gametoclonal variation ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Restriction fragment length polymorphism of the wheat nuclear ribosomal DNA has been studied in several steps of a breeding scheme, including parental genotypes, F1 hybrid, F9 generation, and anther-derived doubled haploid lines obtained from F9. Ribosomal DNA represents a suitable molecular marker in following segregation and possible divergency from expected homozygosity after haploidization of an androgenetic process. It has been shown to undergo variations among the first cycle-doubled haploid lines in the relative amount of two different sizes of ribosomal DNA repeat units. The specificity and peculiar properties of the plant system used allowed us to assign an intrachromosomal location (short arm of the chromosomes 1B, 1R or 6B) to several ribosomal DNA repeat units that differ by the length of their nontranscribed spacer region.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 75 (1988), S. 628-641 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Triplet proteins ; Gliadins ; Glutenins ; Linkage mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A translocation mapping procedure was used to map gene-centromere distances for the genes controlling endosperm proteins on the short arm of each of the chromosomes 1A, 1B and 1D in wheat. The genes controlling triplet proteins (tentatively designated Tri-1) were found to be closely linked to the centromere on chromosome arms 1AS and 1DS and loosely linked to the gliadin genes (Gli-1) on the same arms. The Gli-1 genes segregated independently or were very loosely linked to their respective centromeres. The Gli-B1-centromere map distance on 1BS was also estimated using conventional telocentric mapping and the result was similar to that obtained with the translocation mapping. A simple two-step one-dimensional electrophoretic procedure is described which allows the low-molecular-weight (LMW) glutenin subunits to be separated from the gliadin bands, thus facilitating the genetic analysis of these LMW subunits. No recombination was observed between the genes (designated Glu-3) controlling some major LMW glutenin subunits and those controlling gliadins on chromosome arms 1AS and 1DS. However, in a separate experiment, the genes controlling LMW glutenin subunits on 1BS (Glu-B3) showed a low frequency of recombination with the gliadin genes.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 76 (1988), S. 393-397 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Maize ; Wide-crosses ; Embryo culture ; Haploids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Hybrid embryos from hexaploid wheat x maize crosses rapidly lose the maize chromosomes to produce haploid wheat embryos. Such embryos almost always aborted when left to develop on the plant, and only 1 was recovered from 2440 florets (0.17% of the expected number). Embryos had greater viability in spikelet culture, 47 (26.5% of the expected number) being recovered from 706 ovaries. Thirty-two of these embryos germinated to give green plants, 31 of which were haploid (21 wheat chromosomes) and 1 of which was euploid (42 wheat chromosomes). Spikelet culture enabled 17.1% of the expected number of embryos to be recovered as haploid plants, a 100-fold improvement on allowing embryos to develop in vivo. Ten haploid plants of ‘Chinese Spring’ (kr1, kr2), 13 plants of ‘Chinese Spring (Hope 5A)’ (kr1, Kr2), and 8 of ‘Hope’ (Kr1, Kr2) were recovered. The potential of wheat x maize crosses for wheat haploid production and for gene transfer from maize to wheat is discussed.
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  • 59
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Aegilops ventricosa ; Pseudocercosporella herpotrichoides ; Eyespot resistance ; Chromosome markers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The hexaploid wheat line H-93-70 carries a gene (Pch-1) that has been transferred from the wild grass Aegilops ventricosa and confers a high degree of resistance to eyespot diesease, caused by the fungus Pseudocercosporella herpotrichoides. Crosses of the resistant line H-93-70 with the susceptible wheat Pané 247 and with a 7D/7Ag wheat/Agropyron substitution line were carried out and F2 kernels were obtained. The kernels were cut transversally and the halves carrying the embryos were used for the resistance test, while the distal halves were used for genetic typing. Biochemical markers were used to discriminate whether the transferred Pch-1 gene was located in chromosome 7D, as is the case for a resistance factor present in “Roazon” wheat. In the crosses involving Pané 247, resistance was not associated with the 7D locus Pln, which determines sterol ester pattern (dominant allele in H-93-70). In the crosses with the 7D/7Ag substitution line, resistance was neither associated with protein NGE-11 (7D marker), nor alternatively inherited with respect to protein C-7 (7Ag marker). It is concluded that gene Pch-1 represents a different locus and is not an allele of the resistance factor in “Roazon” wheat.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 173-176 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Tiller index ; Competitive ability ; Interplant competition ; Modified pedigree method of selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A dismal 81% failure of newly bulked lines against checks was observed in Indian wheat material evolved by the pedigree method. This is considered to be the consequence of selection in space planting in early generations followed by yield tests in a competitive environment which did not allow any scope of selection for competitive ability. Thus, most of the homozygous lines, which were until now raised and carried forward under space planting, failed to compete with the checks for yield in close planting. It is, therefore, necessary to modify the method to combine both the competitive ability and identity of selected plants. The proposed modified procedure involves raising the population under spaced planting as well as under drilling from F2 onwards. Evaluation for tiller index marks an important step. On the basis of tiller index, single plants are isolated from spaced populations. Steps of the modified procedure are outlined in detail. The modified method, which economises on breeders' workload and other physical inputs, besides having other advantages, can also be used for certain other grain crops. Preliminary results based on the modified method during the past two seasons have indicated its utility.
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 349-352 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Malate dehydrogenase ; Isozymes ; Triticeae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A third set of malate dehydrogenase loci have been identified and located on the short arms of homoeologous group 5 chromosomes in wheat. Allelic differences have been found at each of the three Mdh-3 loci. However, Mdh-D3 appears to be least variable, with a second allele found only in Sears' ‘Synthetic’ among a survey of 42 varieties. Homoeoloci were identified on chromosome 7 (5H) of Hordeum vulgare, the short arm of 5E in Agropyron elongatum and 5U in Aegilops umbellulata.
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 433-435 
    ISSN: 1432-2242
    Schlagwort(e): Rhizobium ; Irradiation ; Nitrogen fixation ; Vicia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Sumary The objective of this work was to know the behaviour and variability of Rhizobium leguminosarum after irradiation. The induced variation was tested under greenhouse conditions on the variety JV 3 of broad beans (Vicia faba) in six replications. Induced genetic variabilty was observed for strain, parent and mutant versus parent. Out of 24 irradiated strains, strain 93-32 performed better with a greater number of nodules and higher dry weight of nodules per plant and biological yield. Environment played an important role in the expression of characters observed. High heritability and genetic advance of these traits indicated that the nitrogen fixation ability of Rhizobium can easily be improved by selection.
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 436-444 
    ISSN: 1432-2242
    Schlagwort(e): Intergeneric hybrids ; Wheat ; Leymus ; Chromosome pairing ; Meiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Hybrid plants were obtained between Triticum aestivum (2n=6x=42, AABBDD) and Leymus innovatus (2n=4x=28, JJNN) at a frequency varying from 0.4% to 1.2% of the pollinated florets. Improvement of the embryo culture medium resulted in a higher frequency of embryo rescue. Eight of ten hybrids had the expected chromosome number of 35 (ABDJN). Meiotic analysis indicated that there was no homology between the genomes of the two species. Two hybrids had only 28 chromosomes. Comparison of chromosome pairing between the two types of hybrids suggested that Leymus innovatus carries genes that affect chromosome pairing and behavior. The relatively high occurrence of spontaneous doubling in the meiocytes of these hybrids may indicate that backcrossing of the hybrids to wheat should be possible, although frequent chromosome irregularities observed in the meiocytes of the hybrids may decrease the probability of success of this step, which is essential to the process of gene transfer from L. innovatus to wheat.
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 495-504 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Genetic mapping ; RFLPs ; Isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Restriction fragment length polymorphism (RFLP) mapping was attempted using 18 cDNA clones, 14 anonymous and 4 of known function, which had been shown to have homologous DNA sequences on the group 7 chromosomes of wheat. The loci identified by these probes have been mapped on one or more chromosomes in this homoeologous group using linkage data derived from various F2, random inbred, doubled haploid and single chromosome recombinant populations. The maps also include three isozyme loci, five disease resistance loci, two anthocyanin pigment loci and a vernalisation response locus. The mapping data have been used to determine the extent of map co-linearity over the A, B and D genomes, the degree of RFLP variability in the three genomes and the relative efficiency of various restriction enzymes in detecting RFLPs in wheat. The strategy for future mapping in wheat, particularly the use of “alien” genomes or segments, such as that from Aegilops ventricosa used here, is discussed.
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 657-664 
    ISSN: 1432-2242
    Schlagwort(e): Aminopeptidase ; Wheat ; Isoelectric focussing ; Isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Isoelectric focussing was used to separate the isozymes of aminopeptidase of wheat and its relatives. Three distinct homoeoallelic sets of genes have been shown to be present. AMP-1, controlled by genes on the long arms of group 6, has previously been described, but two new systems, AMP-2 (group 4) and AMP-3 (group 7) are described here. The three systems are distinguished by their electrophoretic characteristics, by their genetic control and by their substrate specificity. Intervarietal, interspecific and intergeneric polymorphism has been observed at most of the loci. A further set of isozymes, AMP-4, was detected but the chromosomal control of these could not be determined.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 78 (1989), S. 879-883 
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Anther culture ; Androgenetic responsiveness ; Albinism ; Genetic control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Inheritance of the ability to respond in wheat anther culture was studied from 6×2 reciprocal crosses between six varieties with high and two varieties with low capacity for green plant formation and their parents, replicated in two environments. Effects of genotypes dominated embryo formation and percentages of green plants, accounting for 78.4% and 85.4% of total variation, respectively, while smaller genetic effects were indicated for regeneration. Nuclear genes could explain almost all the genotype effects in this material. Embryo formation showed heterosis over high parent for 5 of the 12 hybrids, while percentages of green plants from the hybrids were intermediate to the parents. General Combining Ability (GCA) could explain 78.8% of the variation for embryo formation among the hybrids, whereas differences in percentage of green plants were dominated by Specific Combining Ability (SCA), accounting for 67.9% of hybrid variation. A positive correlation (r=0.81**) was observed between the genetic capacity for regeneration and green plant formation. Analysis of covariance indicated that effects causing GCA for green plant formation were mainly responsible for this correlation. A regression model with two parallel lines divided the six parent lines with high green plant formation into three groups with respect to their reactions with the two testers. The results are discussed with regard to possible involvement of two sets of nuclear genes affecting the percentage of green plants obtained in wheat anther culture: one set consisting of mainly additive effects affecting green plant percentage through an initial effect on regeneration ability, and another set of two or a few more major genes with dominance or epistatic effects uncorrelated with regeneration.
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Potato research 31 (1988), S. 379-383 
    ISSN: 1871-4528
    Schlagwort(e): rooting ; temperature ; daylength ; transplanting ; yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A series of experiments were conducted in Vietnam to develop a system whereby detached sprouts from physiologically old green sprouted seed tubers could be used to grow potatoes. Three node segments from the mid or basal portion of the detached sprout produced the greatest percentage of shoots and roots. Growth was best in a medium of equal parts of sub-soil, pig manure and brick kiln ash. Sprout cuttings produced plantlets ready for transplanting in 14–20 days with mean daily temperatures of 22 to 24°C. When transplanted in mid-November, yields from sprout cuttings in field experiments were 10 to 18 t/ha which were 33% lower than from healthy seed tubers but more than the national average yield using degenerated seed tubers. Tubers produced by plants grown from sprout stored well and gave good yields when replanted the following year.
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 216 (1989), S. 484-491 
    ISSN: 1617-4623
    Schlagwort(e): Nitrogen fixation ; nifL ; Repression ; Metal ions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The ability of the Klebsiella pneumoniae nifL gene product to antagonise NIFA mediated transcriptional activation from the nifH promoter in vivo was inhibited either by metal deprivation, or by the presence of the iron chelators EDDA or Desferal in the growth medium. This inhibition of the repressive activity of NIFL was reversed by the addition of ferrous or manganous ions to the medium but was unaffected by other transition metals. The dependence on metal ions for NIFL activity was observed when NIFL was overexpressed and when cultures were exposed to oxygen or high levels of fixed nitrogen. Immunochemical evidence suggests that NIFL and NIFA associate to form a functional protein complex. Metal ions are apparently not required for the formation of this complex.
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  • 69
    ISSN: 1617-4623
    Schlagwort(e): glnB ; Klebsiella pneumoniae ; Nitrogen control ; Glutamine synthetase ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The role of theKlebsiella pneumoniae PII protein (encoded byglnB) in nitrogen regulation has been studied using two classes ofglnB mutants. In Class I mutants PII appears not to be uridylylated in nitrogen-limiting conditions and in Class II mutants PII is not synthesised. The effects of these mutations on expression from nitrogen-regulated promoters indicate that PII is not absolutely required for nitrogen control. Furthermore the uridylylated form of PII(PII-UMP) plays a significant role in the response to changes in nitrogen status by counteracting the effect of PII on NtrB-mediated dephosphorylation of NtrC. PII is not involved in thenif-specific response to changes in nitrogen status mediated by NifL.
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  • 70
    ISSN: 1617-4623
    Schlagwort(e): Haemoglobin ; Nitrogen fixation ; Gene expression ; Plant transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Plant haemoglobin genes are known to occur in legume and non-legume families and in both nodulating (e.g. Parasponia andersonii) and non-nodulating species (e.g. Trema tomentosa). Their presence in non-nodulating plants raises the possibility that haemoglobins might serve a function in non-symbiotic tissues distinct from their role in the nitrogen-fixing root nodules induced by micro-organisms. We report here that a P. andersonii haemoglobin promoter can regulate expression of either the P. andersonii haemoglobin gene, or a hybrid construct with the bacterial chloramphenicol acetyltransferase gene (cat), in the nonsymbiotic plant, Nicotiana tabacum. Expression is predominantly in the roots, implying that haemoglobins might have a function in roots of non-nodulated plants. We have also observed a low level of haemoglobin protein in non-nodulated P. andersonii roots, but not leaves, supporting this assertion. The expression in transgenic plants will allow further characterization of the promoter sequences essential for the organ-specific expression of haemoglobins in nonsymbiotic tissues.
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  • 71
    ISSN: 1617-4623
    Schlagwort(e): LMW glutenin ; Seed storage protein ; Molecular evolution ; Tissue-specific expression ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The isolation and characterisation by DNA sequencing of a low molecular weight (LMW) glutenin gene from wheat is described. The deduced protein contains a signal peptide, a central repetitive region rich in proline and glutamine and N and C terminal non-repetitive domains, similar to other prolamins. A detailed comparison of the C terminal domain of 20 prolamin genes enabled us to divide them into 4 families. The LMW glutenin family is distinct from the α, β-and γ-gliadin families of wheat and is closest to the B hordein genes of barley. This and other comparisons were also used to assess the pattern of genetic variation among prolamin sequences and to provide a molecular basis for the interpretation of prolamin size polymorphism. The 5′ flanking fragment of the isolated gene was previously shown to direct endosperm-specific expression of a reporter gene in transgenic tobacco. Evidence is provided that the isolated gene is also active in wheat and its transcription initiation site was determined. Features of the gene which may be relevant to its activity are discussed.
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 213 (1988), S. 238-246 
    ISSN: 1617-4623
    Schlagwort(e): Frankia ; Nitrogen fixation ; Alnus ; Symbiosis ; nifH nucleotide sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Southern blots of Frankia total DNAs were hybridized with nifHDK probes from Rhizobium meliloti, Klebsiella pneumoniae and Frankia strain Arl3. Differences between strains were noted in the size of the hybridizing restriction fragments. These differences were more pronounced among Elaeagnus-compatible strains than among Alnus- or Casuarina-compatible strains. Gene banks constructed for Frankia strains EUN1f, HRN18a, CeD and ACoN24d were used to isolate nif-hybridizing restriction fragments for subsequent mapping and comparisons. The nifH zone had the highest sequence conservation and the nifH and nifD genes were found to be contiguous. The complete nucleotide sequence of the nifH open reading frame (ORF) from Frankia strain Arl3 is 861 bp in length and encodes a polypeptide of 287 amino acids. Comparisons of these nucleic acid and amino acid sequences with other published nifH sequences suggest that Frankia is most similar to Anabaena and Azotobacter spp. and K. pneunoniae and least similar to the Gram-positive Clostridium pasteurianum and to the archaebacterium Methanococcus voltae.
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 214 (1988), S. 541-546 
    ISSN: 1617-4623
    Schlagwort(e): Wheat ; Rye ; Globulins ; Gene mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A new group of proteins soluble in salt solutions and organic solvents (70% ethanol and chloroform-methanol mixtures), but not in water, has been isolated from wheat and rye endosperm. The molecular weights (23–26 kDa) and amino acid compositions of the different fractions characterized suggest a high degree of homology among the major components of the fractions in wheat and rye. Compensating nulli-tetrasomic and ditelosomic lines of hexaploid wheat have been analysed by two-dimensional electrophoresis and genes for these proteins have been assigned to the short arms of chromosomes 1 A, 1 B and 1 D. A similar analysis of Triticum aestivum/Secale cereale and T. aestivum/Agropyron elongatum addition and substitution lines has shown that genes for the corresponding globulins are located in the short arms of group 1 chromosomes of these species.
    Materialart: Digitale Medien
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  • 74
    ISSN: 1617-4623
    Schlagwort(e): Rhodobacter capsulatus ; Nitrogen fixation ; DNA sequence analysis ; nifE, nifN, nifX genes ; Protein comparisons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Rhodobacter capsulatus genes homologous to Klebsiella pneumoniae nifE, nifN and nifX were identified by DNA sequence analysis of a 4282 bp fragment of nif region A. Four open reading frames coding for a 51188 (NifE), a 49459 (NifN), a 17459 (NifX) and a 17472 (ORF4) dalton protein were detected. A typical NifA activated consensus promoter and two imperfect putative NifA binding sites were located in the 377 bp sequence in front of the nifE coding region. Comparison of the deduced amino acid sequences of R. capsulatus NifE and NifN revealed homologies not only to analogous gene products of other organisms but also to the α and β subunits of the nitrogenase iron-molybdenum protein. In addition, the R. capsulatus nifE and nifN proteins shared considerable homology with each other. The map position of nifX downstream of nifEN corresponded in R. capsulatus and K. pneumoniae and the deduced molecular weights of both proteins were nearly identical. Nevertheless, R. capsulatus NifX was more related to the C-terminal end of NifY from K. pneumoniae than to NifX. A small domain of approximately 33 amino acid residues showing the highest degree of homology between NifY and NifX was also present in all nifB proteins analyzed so far. This homology indicated an evolutionary relationship of nifX, nifY and nifB and also suggested that NifX and NifY might play a role in maturation and/or stability of the iron-molybdenum cofactor. The open reading rame (ORF4) downstream of nifX in R. capsulatus is also present in Azotobacter vinelandii but not in K. pneumoniae. Interposon-induced insertion and deletion mutants proved that nifE and nifN were necessary for nitrogen fixation in R. capsulatus. In contrast, no essential role could be demonstrated for nifX and ORF4 whereas at least one gene downstream of ORF4 appeared to be important for nitrogen fixation.
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 146 (1988), S. 18-27 
    ISSN: 1615-6102
    Schlagwort(e): Cytoskeleton ; Endosperm ; Immunofluorescence ; Microtubular assemblies ; Polyethylene glycol ; Triticum ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The three-dimensional structure of the microtubular cytoskeleton of developing wheat endosperm was investigated immunocytochemically. Semi-thin sections were prepared from polyethylene glycol embedded ovaries. At the free-nuclear stage the endosperm cytoplasm with regularly distributed nuclei surrounded a large central vacuole and exhibited an extensive network of fluorescent labelled microtubular assemblies radiating from each nucleus. As was found in other coenocytes, this particular and nuclear-dependent cytoskeletal configuration functions in the arrangement of nuclei and in the stabilization of the nuclear positions. At the beginning of cellularization of the endosperm the formation of vacuoles altered the radiating networks. It is likely that the radiating microtubular arrays function in the formation of phragmoplasts, independent of nuclear divisions. The formation of anticlinal cell walls, giving rise to openended cell cylinders, coincides with the occurrence of phragmoplast microtubular arrays which were demonstrated during the period of cell wall elongation. The microtubular system radiating from the nuclei in these cell cylinders anchored the nuclei in stage- and locus-specific positions. During the development of aleurone and inner endosperm cells, cell morphogenesis was related to earlier demonstrated types of microtubular configurations in the cortical cytoplasm. This suggests that a general mechanism is involved.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 150 (1989), S. 19-26 
    ISSN: 1615-6102
    Schlagwort(e): Nitrogen fixation ; Peanut ; Root nodules ; Dense body ; Microbody ; Oleosome
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Nitrogen-fixing peanut root nodules are characterized by their unique structural organization, distinct from other legume nodules. The focus of this study has been in and around the hostsymbiont interface, where the bacterioid and the host cell surface (peribacteroid membrane envelope) interact during symbiosis. The infected nodule cells have revealed the presence of lipid bodies (oleosomes) in intimate association with the peribacteroid membrane, which encloses the large spherical bacteroids with a relatively narrow peribacteroid space. Electron dense structures, referred to as dense bodies have been found attached to the bacteroid outer membranes at the host-symbiont interface. The dense bodies are osmiophilic, amorphous and 3,3′-diaminobenzidine positive. The isolated intact bacteroids with dense bodies attached to their cell wall showed significant catalase activity. Many microbodies showing DAB-positive reaction have been found in the host cytoplasm, associated closely with the peribacteroid membrane. These ultrastructural and cytochemical characteristics of peanut root nodules suggest that lipids are utilized during symbiosis and the dense bodies and microbodies may be involved in the catabolic process.
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  • 77
    ISSN: 1615-6102
    Schlagwort(e): Plectonema boryanum ; Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Nitrogen starvation ; Immunogold localization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The ultrastructure of fructose-supplemented and unsupplemented nitrogen-fixing (fix +) and nonfixing (fix −)Plectonema boryanum UTEX 581 cells was examined by transmission electron microscopy. The most prominent structural differences included the arrangement and morphology of the thylakoids and alterations in the appearance of the interthylakoidal spaces. These ultrastructural differences, together with other observations such as glycogen content and presence of nitrogenase (using acetylene reduction assay and immunogold localization), readily distinguished nonfixingP. boryanum from nitrogen-fixing cells.
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  • 78
    ISSN: 1615-6102
    Schlagwort(e): Legumes ; Nitrogen fixation ; Nodulation ; Rhizobium ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two methods have been developed in order to discriminate between lateral roots, nodules and root-derived structures which exhibit both root and nodule histological features and which can develop on legumes inoculated with certainRhizobium mutants. The first method, known as the “clearing method”, allows the observation by light microscopy of cleared undissected root-structures. The second, known as the “slicing method”, is a complementary technique which provides a greater degree of structural information concerning such structures. The two methods have proved invaluable in defining unequivocally the nature of the interaction between a rhizobial strain and a legume host.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Journal of applied phycology 1 (1989), S. 59-65 
    ISSN: 1573-5176
    Schlagwort(e): temperature ; acclimation ; Eucheuma alvarezii ; Eucheuma isiforme
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Branch cultures ofEucheuma alvarezii Doty var.tambalang Doty, farmed in the Philippines, andE. isiforme (C. Agardh) J. Agardh var.denudatum Cheney, from the west coast of Florida, were gradually transferred through three temperature regimes over a 6-week period. Photosynthetic responses were measured under a series of irradiances (P-I curves) and temperatures to determine immediate responses of the plants before, during and after completion of the transfers. The Philippine variety did not show acclimation to 18 °C either after gradual transfer from the initial culture temperature of 25 °C or when abruptly transferred from 25 to 18 °C. The Florida variety did show acclimation to 25 °C when gradually transferred from 18 to 22 to 25 °C over the 6-week period, but not if abruptly transferred from 18 to 25 °C. The west coast variety ofE. isiforme from Florida shows a temperature acclimation ability that parallels the seasonal changes in water temperature of its habitat.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 119 (1989), S. 87-97 
    ISSN: 1573-5036
    Schlagwort(e): irradiance ; root development ; root growth ; shoot development ; shoot growth ; temperature ; thermal time ; winter wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Wheat plants were grown in columns of soil until early stem elongation at a wide range of constant root temperatures. Two light environments were imposed and three levels of nitrogen fertilizer added at sowing. Shoot and root development and growth were measured by destructive sampling to investigate the combined effects of temperature and changing nutrient and assimilate supply. Both mainstem leaf and root axis production were linearly related to thermal time above a base temperature of 0°C. Low irradiance affected the appearance of mainstem tillers and associated nodal root axes. Nitrogen had little effect on shoot or root development but increased shoot area between 6 and 8 mainstem leaves. Higher temperatures and supplementary light resulted in larger root systems when compared at equivalent times after sowing. Total root length and root dry weight increased exponentially with thermal time, based on the mean of 4 cm soil and 2 cm air temperatures, but no single relation existed for all temperature and light treatments. Total plant dry matter, root length and root dry weight increased linearly with accumulated, intercepted, photosynthetically active radiation. Root growth responded less than the shoot to supplementary light. Increasing temperature reduced the proportion of root weight to total plant weight.
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 119 (1989), S. 99-110 
    ISSN: 1573-5036
    Schlagwort(e): Irradiance ; root development ; root growth ; temperature ; thermal time ; winter wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Winter wheat was sown on 2 dates with 3 levels of nitrogen fiertiliser (0, 50 and 200 kg N ha−1) in one year and on 2 sites in a followign season. Shoot and root development and growth were measured between emergence and anthesis in the first season and emergence and 7 mainstem leaves in the second. Differences in temperature and light regime led to significant differences in shoot and root development and growth between sowing dates. A thermal time-scale, based on soil surface or air temperatures, with a base of 0°C, adequately described the production of mainstem leaves and nodal root axes over all treatments. Autumn applied nitrogen had little effect on development. Shoot growth and green area index increased exponentially with thermal time prior to spring nitrogen application and the completion of canopy development. Early-sown crops had larger root systems than late-sown crops prior to winter and this divergence was retained until anthesis. The relationship between root growth and thermal time was little better than with days after sowing and was not improved by either varying the site of temperature measurement or the base temperature used for calculation. Differences in soil texture and drainage, between sites, led to significant changes in root length distribution. Although spring applied nitrogen generally increased root length, its effects were inconsistent. There was a curvilinear relation between root length and the amount of photosynthetically active radiation (PAR) intercepted; this relation was unaffected by sowing date or nitrogen treatment. The amount of root produced per unit PAR decreased as the season progressed, reflecting the decrease in the proportion of total dry matter partitioned to the root system.
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  • 82
    ISSN: 1617-4623
    Schlagwort(e): Rhizobium leguminosarum ; Nitrogen fixation ; nif/fix genes ; Escherichia coli minicells ; Transcription regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary On the Rhizobium leguminosarum PRE sym plasmid, fixABC and a novel gene fixW were identified upstream of the regulatory gene nifA. The molecular masses of FixABC, 29, 44 and 50 kDa respectively, were estimated by polyacrylamide gel electrophoresis (PAGE) and of FixW, 25 kDa, by PAGE and nucleotide sequencing. Hybridization studies using bacteroid mRNA as a probe showed that fixABC is one operon which can be transcribed independently of fixW. Nucleotide sequencing revealed that both fixW and fixA are preceded by a nif consensus promoter. The fixA promoter partly overlaps the 3′-terminal coding region of fixW, indicating that readthrough from fixW into fixA is possible. Two open reading frames, ORF71 and ORF79, precede fixW and form one operon with fixW. ORF71 contains sequences homologous to the fixA promoter and 5′-terminal coding region. One more duplication of fixA sequences was detected, also located within the sym plasmid nif/fix clusters. One duplication of fixW sequences was found. No fixW homologue could be found in other nitrogen fixing organisms except in a number of R. leguminosarum strains.
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  • 83
    ISSN: 1617-4623
    Schlagwort(e): Nitrogen fixation ; draT ; draG ; TTG initiation codon
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Nitrogen fixation activity in the photosynthetic bacterium Rhodospirillum rubrum is controlled by the reversible ADP-ribosylation of the dinitrogenase reductase component of the nitrogenase enzyme complex. This report describes the cloning and characterization of the genes encoding the ADP-ribosyltransferase (draT) and the ADP-ribosylglycohydrolase (draG) involved in this regulation. These genes are shown to be contiguous on the R. rubrum chromosome and highly linked to the nifHDK genes. Sequence analysis revealed the use of TTG as the initiation codon of the draT gene as well as a potential open reading frame immediately downstream of draG. The mono-ADP-ribosylation system in R. rubrum is the first in which both the target protein and modifying enzymes as well as their structural genes have been isolated, making it the model system of choice for analysis of this post-translational regulatory mechanism.
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 212 (1988), S. 27-37 
    ISSN: 1617-4623
    Schlagwort(e): Rhodobacter capsulatus ; Nitrogen fixation ; nifA/nifB duplication ; Deletion analysis ; DNA sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A DNA region showing homology to Klebsiella pneumoniae nifA and nifB is duplicated in Rhodobacter capsulatus. The two copies of this region are called nifA/nifB copy I and nifA/nifB copy II. Deletion mutagenesis demonstrated that either of the two copies is sufficient for growth in nitrogen-free medium. In contrast, a double deletion mutant turned out to be deficient in nitrogen fixation. The complete nucleotide sequence of a 4838 bp fragment containing nifA/nifB copy I was determined. Two open reading frames coding for a 59653 (NifA) and a 49453 (NifB) dalton protein could be detected. Comparison of the amino acid sequences revealed that the R. capsulatus nifA and nifB gene products are more closely related to the NifA and NifB proteins of Rhizobium meliloti and Rhizobium leguminosarum than to those of K. pneumoniae. A rho-independent termination signal and a typical nif promoter region containing a putative NifA binding site and a consensus nif promoter are located within the region between the R. capsulatus nifA and nifB genes. The nifB sequence is followed by an open reading frame (ORF1) coding for a 27721 dalton protein in nifA/nifB copy I. DNA sequence analysis of nifA/nifB copy II showed that both copies differ in the DNA region downstream of nifB and in the noncoding sequence in front of nifA. All other regions compared, i.e. the 5′ part of nifA, the intergenic region and the 3′ part of nifB, are identical in both copies.
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 212 (1988), S. 531-535 
    ISSN: 1617-4623
    Schlagwort(e): Gene regulation ; Nitrogen fixation ; nod genes ; Peas ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Gene(s) conferring the ability of Rhizobium leguminosarum biovar viciae strain TOM to nodulate primitive peas (cultivar Afghanistan) had been located in a 2.0 kb region of its sym plasmid, pRL5JI. In this DNA, a single open reading frame of 1101 bp, corresponding to a gene, nodX was found. nodX is downstream of nodJ which is present in strain TOM and also in the sym plasmid of a typical strain of this biovar. nodX specifies a hydrophobic protein (of Mr 41 036) with no clear similarity to other proteins in data bases. Mutations in nodX abolished nodulation of Afghanistan peas but not nodulation of commercial peas. nodX-lacZ fusions were used to show that transcription of nodX was activated by root exudates from both commercial and Afghanistan peas and by defined flavonoids. Exudate from Afghanistan peas activated nod genes of typical strains of R. leguminosarum biovar viciae which fail to nodulate these peas; thus, their failure to nodulate these primitive peas is not due to a lack of activation of their nod genes by exudate from Afghanistan peas. A homologue of nodX exists in R. leguminosarum biovar trifolii (which nodulates clover) but not in typical strains of R. leguminosarum biovar viciae.
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  • 86
    ISSN: 1617-4623
    Schlagwort(e): Azorhizobium caulinodans ; Nitrogen fixation ; fixABC gene ; nifO ; Nitrogenase activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The fast growing strain, Azorhizobium caulinodans ORS571, isolated from stem nodules of the tropical legume Sesbania rostrata, can grow in the free-living state at the expense of molecular nitrogen. Five point mutants impaired in nitrogen fixation in the free-living state have been complemented by a plasmid containing the cloned fix-ABC region of strain ORS571. Genetic analysis of the mutants showed that one was impaired in fixC, one in fixA and the three others in a new gene, located upstream from fixA and designated nifO. Site-directed Tn5 mutagenesis was performed to obtain Tn5 insertions in fixB and fixC. The four genes are required for nitrogen fixation both in the free-living state and under symbiotic conditions. The nucleotide sequence of nifO was established. The gene is transcribed independently of fixA and does not correspond to fixX, recently identified in Rhizobium meliloti and R. leguminosarum. Biochemical analysis of the five point mutants showed that they synthesized normal amounts of nitrogenase components. It is unlikely that fixA, fixC and nifO are involved in electron transport to nitrogenase. FixC could be required for the formation of a functional nitrogenase component 2.
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 215 (1988), S. 134-138 
    ISSN: 1617-4623
    Schlagwort(e): glnB ; Klebsiella pneumoniae ; Nitrogen control ; Glutamine synthetase ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The glnB gene of Klebsiella pneumoniae, which encodes the nitrogen regulation protein PII has been cloned and sequenced. The gene encodes a 12429 dalton polypeptide and is highly homologous to the Escherichia coli glnB gene. The sequences of a glnB mutation which causes glutamine auxotrophy and of a Tn5 induced Gln+ suppressor of this mutation were also determined. The glutamine auxotrophy was deduced to be the result of a modification of the uridylylation site of PII and the suppression was shown to be caused by Tn5 insertion in glnB. The 3′ end of an open reading frame of unknown function was identified upstream of glnB and may be part of an operon containing glnB. Potential homologues of glnB encoding polypeptides extremely similar in sequence to PII were identified upstream of published sequences of the glutamine synthetase structural gene (glnA) in Rhizobium leguminosarum, Bradyrhizobium japonicum and Azospirillum brasilense.
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 215 (1989), S. 507-516 
    ISSN: 1617-4623
    Schlagwort(e): Nitrogen fixation ; Regulation ; Rhodobacter capsulatus ; Gene sequences ; Transcription factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have determined the DNA sequence for the genes nifR1, nifR2 and nifR4 in the photosynthetic bacterium Rhodobacter capsulatus. These genes regulate transcription of the nifHDK operon and so limit the expression of nitrogen fixation activity to periods of low environmental concentrations of both oxygen and fixed nitrogen. The sequences of these three genes are similar to components of the ntr regulation system in Escherichia coli and Klebsiella pneumoniae. The two-component regulatory system of ntrB and ntrC in E. coli is represented by nifR2 and nifR1 in R. capsulatus and nifR4 in R. capsulatus is the equivalent of the E. coli ntr-related sigma factor ntrA.
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  • 89
    ISSN: 1435-1536
    Schlagwort(e): Circular dichroism ; gelatin ; sodium alkyl sulphates ; aqueousgelatinsolutions ; secondary structure ; pH ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The modification of the triple helical structure in aqueous gelatin solutions by changing pH and adding alkyl sulphates at 298 K and after rechilling the solution to 283 K was investigated by CD-measurement. At 298 K the triple helical content at the IEP of the gelatin has its maximum value. It is only weakly affected by adding sodium dodecyl sulphate (SDDS) at concentrations 〈10−4 M/dm3. The unfolding of the triple helix affected by pH and SDDS is reversible by rechilling the solution. The triple helical content of gelatin solutions decreases at SDDS concentrations higher than 10−4 M/dm3. In all cases the decrease of the amount of triple helical structure is connected with an increase of the cis-configuration in single chains and leads to chain reversals. At sufficiently high SDDS concentrationsβ-sheets are formed. These changes are thermally irreversible. Sodium decyl sulphate (SDS) has a more minor influence than SDDS except in the range of the c.m.c. of SDS. At sufficiently high SDS concentrations,β-turns appear.
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  • 90
    ISSN: 1573-5036
    Schlagwort(e): arctic ; Eriophorum ; pH ; phosphatases ; phosphorus ; PNPPase ; root enzymes ; temperature ; tundra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Eriophorum vaginatum L. subsp.spissum (Fern.) Hult., a dominant plant in arctic tundra ecosystems, has acid phosphatase activity evenly distributed along its root surface from the root tip to a distance at least 16 cm from the tip. These root surface phosphatases have optimal activity from pH 3.5 to 4.0; mean soil pH for soil samples collected with roots was 3.69. Apparent energy of activation and Q10 values (14.0 kcal mol−1 and 2.2, respectively) do not provide evidence for temperature acclimation, but substantial phosphatase activity was measured at 1°C. Kinetic parameters determined for this root surface phosphatase were as follows: Km=9.23 mM, Vmax=1.61×10−3 μmoles mm−2h−1. The presence of inorganic phosphorus in the assay medium did not inhibit root surface phosphatase activity except at very high concentrations (100 mM); even then, only slight inhibition was detected (7 to 19%). A comparison of hydrolysis rates with inorganic phosphate assimilation rates measured forE. vaginatum indicates that organic phosphate hydrolysis may occur at approximately one third the rate of inorganic phosphate absorption. Calculations show that inorganic phosphate produced by root surface phosphatase activity may satisfy 65% of the annual phosphate demand ofE. vaginatum. Since arctic tundra soils are typically higher in dissolved organic phosphorus compounds than in inorganic phosphate, root surface phosphatase activity may make a considerable contribution to the phosphate nutrition of this widespread and abundant arctic plant.
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 41 (1989), S. 65-69 
    ISSN: 1573-5060
    Schlagwort(e): Fragaria ; Potentilla ; intergeneric hybrids ; pollen storage ; temperature ; relative humidity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Low temperature and humidity were used for the storage of pollen of four species of Fragaria (2n=14, 42 and 56) and two species of Potentilla (2n=14). The stainability of Fragaria pollen was assessed over a number of years by use of aceto-carmine stain and its viability by cross-pollinations; stainability of Potentilla pollen was assessed by acetocarmine. Fragaria pollen so stored remained stainable for seven years and showed the ability to set seed for three years. over the latter period, aceto-carmine staining gave a reasonable prediction of seed set produced by the stored pollen of Fragaria and so is of value in estimating pollen viability in that genus. Potentilla pollen remained stainable for three years.
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Photosynthesis research 21 (1989), S. 17-26 
    ISSN: 1573-5079
    Schlagwort(e): chlorophyll fluorescence ; herbicide binding ; photoinhibition ; photosynthesis ; photosystem II ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The time courses of some Photosystem II (PS II) parameters have been monitored during in-vivo and in-vitro photoinhibition of spinach chloroplasts, at room temperature and at 10 °C or 0 °C. Exposing leaf discs of low-light grown spinach at 25 °C to high light led to photoinhibition of chloroplasts in-vivo as manifested by a parallel decrease in the number of functional PS II centres, the variable chlorophyll fluorescence at 77K (F v /F m ), and the number of atrazine-binding sites. When the photoinhibitory treatment was given at 10 °C, the former two parameters declined in parallel but the loss of atrazine-binding sites occurred more slowly and to a lesser extent. During in-vitro photoinhibition of chloroplast thylakoids at 25 °C, the loss of functional PS II centres proceeded slightly more rapidly than the loss of atrazine-binding sites, and this difference in rate was further increased when the thylakoids were photoinhibited at 0 °C. During the recovery phase of leaf discs (up to 9 h) the increases in F v /F m preceded that of the number of functional PS II centres, while only a further decline in the number of atrazine-binding sites was observed. The recovery of variable chlorophyll fluorescence and the concentration of functional PS II centres occurred more rapidly at 25 °C than at 10 °C. These results suggest that the photoinhibition of PS II function is a relatively temperature-independent early photochemical event, whereas the changes in the concentration of herbicide-binding sites appear to be a more complex biochemical process which can occur with a delayed time course.
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  • 93
    ISSN: 1573-5036
    Schlagwort(e): Azospirillum ; Azotobacter ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Out of ten isolates ofAzospirillum spp. isolated from the root and rhizosphere of wheat plant, seven belonged toA. brasilense and three belonged toA. lipoferum. All eight isolates ofAzotobacter spp. belonged toAzotobacter chroococcum. Two strains, one fromA. lipoferum and another fromA. chroococcum having high nitrogen fixing capacity with negative test for denitrification were used as inoculant to supplement the nitrogen need of wheat crop. Significant increases in the yield of wheat grain and uptake of nitrogen by the crop over the control were found in pot tests when the seeds were inoculated either withAzospirillum spp. orAzotobacter spp. or the combination of both the inoculants.
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 109 (1988), S. 139-140 
    ISSN: 1573-5036
    Schlagwort(e): emergence ; germination ; Glycine max ; soybean ; seed ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract ‘Bragg’ and ‘Cobb’ soybean [Glycine max (L.) Merr.] seeds were germinated in sand at temperatures ranging from 25 to 40°C. Emergence decreased with increasing temperature above 37°C, with virtually no emergence at 40°C. Emergence of 12 other cultivars at 38°C ranged from 25 to 95%. ‘Foster and ‘Coker 338’ were more sensitive to high temperature than the other cultivars.
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 109 (1988), S. 227-234 
    ISSN: 1573-5036
    Schlagwort(e): acetylene reduction ; diurnal cycles ; nitrogen fixation ; oxygen permeability ; photosynthesis ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract While diurnal cycles in nitrogen fixation rates are sometimes assumed to result from diurnal variation in photosynthetically active radiation, contradicting evidence exists that indicate soil temperature is the primary environmental influence. These studies assessed the significance of temperature on soybean nitrogen fixation under field conditions. Two groups of intact field-grown soybean plants, one at ambient and the other exposed to a 10°C diurnal variation in soil temperature, were nondestructively assayed for acetylene reduction rates. Activity was closely associated with soil temperature (R2=0.85), even when temperature was 12 h out of phase with ambient. Data were also obtained to determine if the effects of rhizosphere temperature on nitrogen fixation are mediated through an effect on the nodule oxygen permeability. Nodule oxygen permeability of intact, aeroponically grown soybean was closely correlated with the diurnal changes in temperature (R2=0.90).
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 40 (1989), S. 121-126 
    ISSN: 1573-5060
    Schlagwort(e): Chrysanthemum morifolium ; chrysanthemum ; tolerance ; temperature ; days to flower ; breeding ; component analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Twenty seven clones of chrysanthemum, 19 of which were selected at low temperature, were flowered at 10, 14, 18 and 22°C. The number of days to flower in response to temperature could, for each genotype, be described by a parabola with the parameters: optimum temperature, days to flower at the optimum temperature and curvature which represents the sensitivity to temperature. The low-temperature selections did not have a reduced optimum temperature but reduced sensitivity to temperature accounted for most of the ability to flower at low temperature. The parameters may vary independently. Examples are given to show how these parameters can be combined to construct genotypes with a required temperature response.
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  • 97
    ISSN: 1573-5117
    Schlagwort(e): Acanthocyclops ; productivity ; temperature ; food limitation ; generation time
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The generation time of the predatory cyclopoid copepod Acanthocyclops robustus was estimated on 11 occasions during the years 1980 to 1982 in Alderfen Broad. In a multiple regression model, generation time was found to be uncorrelated with temperature, positively correlated (p 〈 0.05) with the densities of Bosmina longirostris and rotifers, and negatively correlated (p 〈 0.001) with the density of nauplii of the calanoid copepod Eudiaptomus gracilis. It is suggested that generation time was determined largely by the availability of calanoid nauplii as prey, even though these constituted only 2% of zooplankton standing biomass.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 184 (1989), S. 79-88 
    ISSN: 1573-5117
    Schlagwort(e): Cyclopoid copepods ; development times ; eggs ; instars ; temperature ; diapause
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The duration times of eggs, combined naupliar instars and of the different copepodite stages of five species of cyclopoid copepods — Acanthocyclops robustus, Cyclops vicinus, Diacyclops bicuspidatus, Mesocyclops leuckarti, and Thermocyclops crassus — were investigated at five different temperatures. The five species can be divided in two groups: two species, C. vicinus and D. bicuspidatus, adapted to cold water conditions and three species, A. robustus, M. leuckarti and T. crassus adapted to warm water conditions. The cold water species showed a faster egg development than M. leuckarti and T. crassus at 5–15 °C. The eggs and instars of the warm water species M. leuckarti tend to develop faster than those of the former two species at higher temperatures. A. robustus showed the shortest egg and instar development at 10–25 °C. The warm water species T. crassus produced no eggs at 10 °C and temperatures below. At higher temperatures (20, 25 °C) the egg and instar duration times were similar or longer than those of the other species. When cultured in total darkness a great part of the CIV respectively CV copepodites of the summer forms entered arrest and the percentage of copepodites that showed an arrest of development was highest at lowest temperatures. The present results are compared with data from literature and differences are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 186-187 (1989), S. 81-102 
    ISSN: 1573-5117
    Schlagwort(e): rotifers ; rate of population increase ; life span ; temperature ; salinity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A review of temperature and salinity effects on rotifer population dynamics is presented together with original data of these effects for three clones of Brachionus plicatilis. There is a clear relationship between temperature and the intrinsic rate of increase, r: an increase of temperature — within the natural environmental range — produces an exponential increase of r, and the slope of the response depends on the genotype. The effect of salinity is also genetically dependent; the highest r for each clone is observed at the salinity close to that of its environmental origin. The response of r to temperature is mainly a consequence of the response of the individual rates of development and reproductive timing. The effect of temperature on fecundity (number of descendents per individual life time) is negligible when temperature values are within the normal habitat ranges. On the other hand, salinity seems to affect primarily fecundity. The interaction salinity-temperature may be important in clones or species living in fluctuating environments with positive response to the more frequent combinations found in the corresponding habitats.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 186-187 (1989), S. 129-136 
    ISSN: 1573-5117
    Schlagwort(e): Hexarthra ; salinity ; alkalinity ; wind action ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In Neusiedler See, a shallow alkaline lake with fluctuating water level and salinity, four species of Hexarthra occur: H. mira, H. fennica, H. jenkinae (occasional) and H. polyodonta. The analysis of longterm data reveals a general phenological pattern which does not change from year to year. They first occur in May, develop a maximum in June/July, sometimes a second one in August/September and disappear in October. But the species succession is different in the various years, occasionally only one species (H. mira or H. polyodonta) being present. There is a fairly consistent relation between the chemical conditions and the prevalent species; an increase in salinity favours the development of H. polyodonta. Low temperature and wind generated suspended particles have a negative influence on the development of the Hexarthra populations. Smaller populations of Hexarthra are in a relation to the occurrence of Leptodora indicating predation pressure of the latter species. In Neusiedler See the Hexarthra populations seem to be controlled to a great extent by abiotic factors, but predation by Leptodora and most probably by young fish seems to play an important role too.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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