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11.
Abrotanella forsterioides afrorded euparin, 6-hydroxytremetone and three 6-hydroxytoxol esters, one of them not being isolated previously. Furthermore a seco-triterpene was isolated. The tribal position of the genus Abrotanella in the Compositae is still an unsolved problem. Morphological investigations suggest that this genus should be transferred from the tribe Anthemideae to the Senecioneae [1,2]. So far two species have been studied chemically; one atforded ent-kaurane derivatives, while both contained euparin and hydroxytremetone [3]. 相似文献
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Zusammenfassung In Fortsetzung unserer Untersuchungen über den Zusammenhang von Chloroplastenstruktur und-funktion wurde die Veränderung der Chloroplastenstruktur bei der Adaptation photo-heterotroph kultivierter Organismen an photo-autotrophe Ernährungsbedingungen untersucht. Die Bildung von Partitions aus zuvor isolierten Thylakoiden erfolgt parallel zum Anstieg der photosynthetischen CO2-Assimilation.
Conformational changes of the submicroscopic chloroplast structure and physiological activity of Chlamydobotrys stellata
Summary Our investigation of the connection between the submicroscopic structure and the function of chloroplasts has been continued. It could be demonstrated that the formation of partitions from isolated thylakoids takes place parallel to the increase of photosynthetic activity.相似文献
15.
Zusammenfassung Die Chloroplasten von photo-autotroph (Licht + CO2) oder photo-heterotroph (Licht + Acetat) gewachsenen Chlamydobotrys stellata werden elektronenmikroskopisch untersucht. Es wird eine nahe Beziehung zwischen der Chloroplasten-Feinstruktur und der Ernährungsart gefunden. Die Thylakoide der Chloroplasten photo-heterotroph kultivierter Algen sind im allgemeinen durch Stroma voneinander getrennt und nur zu wenigen gestapelt. In photo-autotrophen Organismen kommt es durch Bildung einer charakteristischen Faltungsstruktur von Thylakoidmembranen zur Bildung von Grana (Pseudo-Grana).Die Ergebnisse werden im Hinblick auf die Photosynthese und Photoassimilation von Acetat bei Chlamydobotrys stellata diskutiert.
Relationship between submicroscopic chloroplast structure and type of carbon nutrition of Chlamydobotrys stellata
Summary Chloroplasts from Chlamydobotrys stellata grown photo-autotrophically (light + CO2) or photo-heterotrophically (light + acetate) have been investigated by means of electronmicroscopy. A close relationship between chloroplast fine structure and type of nutrition could be observed. Thylakoids in chloroplasts from photo-heterotrophically cultivated algae are generally separated from each other by stroma and only few thylakoid packages are present. In photo-autotrophic organisms, however, characteristic folding structure of thylakoid membranes results in the formation of grana (pseudo-grana).These results are discussed in respect to chloroplast function in photosynthesis and photoassimilation of acetate in Chlamydobotrys stellata.相似文献
16.
The isolation and specific activity of rabbit-muscle glyceraldehyde phosphate dehydrogenase 总被引:12,自引:4,他引:8 下载免费PDF全文
W. Ferdinand 《The Biochemical journal》1964,92(3):578-585
17.
Leo A. J. Nagelkerke Ferdinand A. Sibbing Jos G. M. van den Boogaart Eddy H. R. R. Lammens Jan W. M. Osse 《Environmental Biology of Fishes》1994,39(1):1-22
Synopsis All living species occupy an ecological niche, and are positioned within a trophic hierarchy. Extinct organisms presumably
held similar behavioral and coevolutionary characteristics in the past, and were susceptible to the same kinds of natural
ecological pressures operating today. Paleoecological investigations are limited by the incompleteness of the fossil record,
and particularly by a lack of behavioral data that are so fundamental to ecological studies of living communities and habitats.
Opportunities to examine the coevolutionary structure of ancient communities from empirical data are extremely rare. One such
opportunity is provided by the Lower Cretaceous Santana Formation of north-eastern Brazil, a series of richly fossiliferous
strata approximately 110 million years old. Many fossil fishes from the Santana Formation contain identifiable prey, including
decapod crustaceans and fishes. A trophic hierarchy of these organisms is reconstructed here, and their ecological relationships
are discussed. Comparison is made with a similar fish fauna from the Upper Jurassic Solnhofen Limestone of Germany. Low-level,
intermediate and high-level predators are identified in each fauna. Predator-prey relationships in the Santana fauna are strongly
hierarchical, and are more focussed at the intermediate predator level than in Solnhofen. Comparison with a model of predator-prey
relationships between fishes and benthic fauna of the Baltic Sea (which like the Araripe Basin represents a semi-enclosed
environment) suggests that heavy predation on teleosts such asRhacolepis, occupying an intermediate trophic level, may have permitted benthic decapods to proliferate and exclude other benthic organisms.
Less intense predation on fishes at the intermediate trophic level would allow their numbers to increase, thereby increasing
the intensity of predation on the benthos at the base of the trophic hierarchy. 相似文献
18.
Dr. Koffi Christophe Kobenan Dr. Ibrahime Sinan Kouadio Dr. Malanno Kouakou Dr. Pierre Silvie Dr. Kra Norbert Bini Kouadio Dr. Kouadio Emmanuel N'goran Dr. Brou Julien Kouakou Dr. Nogbou Ferdinand Amangoua Dr. Kouakou Etienne Tehia Dr. Abdullahi Ibrahim Uba Prof. Dr. Gokhan Zengin 《化学与生物多样性》2023,20(8):e202300411
Faced with the serious consequences resulting from the abusive and repeated use of synthetic chemicals, today rethinking crop protection is more than necessary. It is in this context that the essential oils of the Lamiaceae Ocimum gratissimum and Ocimum canum, the Poaceae Cymbopogon citratus and nardus and a Rutaceae Citrus sp. of known chemical compositions were experimented. The evaluation of the larvicidal potential of the essential oils was done by the method of topical application of the test solutions, on the L1−L2 stage larvae from the first generation of S. frugiperda obtained after rearing in an air-conditioned room. Lethal concentrations (LC10, LC50 and LC90) were determined after 48 h. After assessing the larvicidal potential of essential oils, molecular docking was carried out to study protein-ligand interactions and their propensity to bind to insect enzyme sites (AChE). The essential oil of O. gratissimum was the most effective with the lowest lethal concentrations (LC10=0.91 %, LC50=1.91 % and LC90=3.92 %). The least toxic oil to larvae was Citrus sp. (LC10=5.44 %, LC50=20.50 % and LC90=77.41 %). Molecular docking revealed that p-cymene and thymol from O. gratissimum essential oil are structurally similar and bind to the AChE active site via predominantly hydrophobic interactions and a H-bond with Tyr374 in the case of thymol. The essential oil of O. gratissimum constitutes a potential candidate for the development of biological insecticides for the fight against insect pests and for the protection of the environment. 相似文献
19.
The high-affinity uptake system of phosphatelimited cyanobacterium Anacystis nidulans [Synechococcus leopoliensis (Raciborski) Komarek] is characterized by a threshold value below which uptake cannot occur. Here it is shown that, if phosphate-limited cyanobacteria are challenged with a short pulse of high phosphate concentration that appreciably exceeds this threshold value, the uptake system undergoes an adaptive response, leading to the attainment of new kinetic properties and a new threshold value. These new properties are maintained for several hours after the pulse. A notable characteristic of this new state is a wide linear dependence of the uptake rate on the external phosphate potential that is a function of the driving force of the uptake process. According to theoretical arguments it is shown that this “linear operation mode” can be explained by the simultaneous operation of several uptake systems with different, staggered threshold values and kinetic properties. Moreover, the new linear uptake properties, in turn, reflect the prehistory of phosphate supply experienced by the population. The consequences of this result with regard to environmental fluctuations of the phosphate concentration in lakes are discussed. 相似文献
20.
Gernot Falkner Ferdinand Wagner John Victor Small Renate Falkner 《Journal of phycology》1995,31(5):745-753
The blue-green alga Anacystis nidulans Drouet (Synechococcus leopoliensis Raciborski) cultivated under phosphate-limited conditions adopts a threshold value in the nanomolar range below which uptake ceases. In this study, we investigated the influence of phosphate pulses on the regulation of uptake behavior during reestablishment of the threshold value. Short-term pulses had only a slight effect on uptake kinetics and, hence, on the threshold value, even if the population had been exposed several times to elevated concentrations above the steady-state level in the growth medium. The threshold value was also practically insensitive to the amount of phosphate stored during these short-term fluctuations. Long-term phosphate pulses resulted in a transition to a metastable state that was characterized by a severalfold higher threshold value. This transition, apparently an adaptation to the transiently elevated phosphate concentrations, was further studied by following the influx of 32 P-phosphate at constant external concentrations and was shown to be complete after a period of 10–20 min. After adaptation to pulses, the uptake behavior followed a linear flow-force relation over a wide range of external concentrations. This behavior was explained by the simultaneous operation of at least two uptake systems with different, but coordinated kinetic parameters. This linear flow-force relation facilitated a direct determination of the threshold value from uptake measurements. For applicability in the field the force-flow relation can be a diagnostic tool to assay for fluctuating phosphate and to establish threshold values below the normal measurable range . 相似文献