Tannenmischwälder und Schuttwälder im Tal der mittleren Lužnice und oberen Moldau in Südböhmen,Tschechoslowakei

Die vorliegende Arbeit befasst sich mit den phytozönologischen Verhältnissen und der Ökologie der Tannen- und Schuttwälder in den Durchbruchstälern der mittleren Lu?nice und oberen Moldau in Südböhmen. Die Schuttwälder werden durch die Ass.Querco robori-Aceretum repräsentiert, die vorwiegend im Tale der Lu?nice in zwei Subassoziationen u. zw.typicum undlunarietosum verbreitet ist. In den Gesellschaften der Tannenhangwälder auf nichtvernässten Böden wurden zwei Assoziationen unterschieden: krautreiche Linden-Tannenwälder repräsentiert die Ass.Tilio-Abietetum mit Subass.typicum, stellarietosum undlumarietosum, die zum VerbandTilio-Acerion Klika 1955 gehört, azidophile Tannenwälder die Ass.Deschampsio flexuosae-Abietetum, die in den VerbandLuzulo-Fagion Lohm. etTüxen 1954 inTüxen 1954 eingereiht wird.     

Bemerkungen zuLotus alpinus Schleich,ex.Ser. in Österreich

Zusammenfassung DiploiderL. alpinus Schleich. exSer., mit 2n=12, ist in den Alpen in Österreich im ganzen Gebiet verbreitet, stellenweise auf den Almwiesen häufig. In den westlichen Teilen habe ich auf ähnlichen Standorten morphologisch parallele tetraploide Formen mit 2n=24 gefunden — wahrscheinlich Ökomorphosen der veränderlichen und plastischen ArtLotus corniculatus L. Durch ihr Vorkommen schließen sich beide Typen aus und treten auch nirgends gemeinsam auf.Für die Gesamtcharakteristik der ArtL. alpinus Schleich. exSer. wird es notwendig sein, noch eine Reihe von Populationen aus verschiedenen Teilen des Areals zytologisch zu untersuchen, die Verbreitung genauer zu bestimmen und einige Merkmale durch langfristige Versuche zu untersuchen.     

Azidophile Eichenwälder auf Quarziten im Tribeč-Gebirge,Slowakei

Die azidophilen Ginster-Traubeneichenwälder, die als Dauerstadien der Sukzession auf Quarziten im Tribe?-Gebirge in der Westslowakei verbreitet sind, gehören systematisch zur AssoziationGenisto pilosae-Quercetum petraeae Zólyomi, Jakucs, Fekete inZólyomi etJakucs 1957. Diese Assoziation zerfällt in zwei Subassoziationen, die sich durchphytozönologische Zusammensetzung und durch verschiedene Ökologie interscheiden: Subass.Quercetosum und Subass.fagetosum. Die beschriebene Assoziation ist auf flachgründigen, stark saueren Böden verbreitet, die bodentypologisch zu oligotrophen Rankern oder Ranker-Braunerden gehören.     

Studium autopathischer und allelopathischer Eigenschaften von Kulturpflanzen durch Folgekulturen-Methode

V práci byl sledován vliv p?edplodin lnu, ?ita, máku a ho??ice na následné plodiny tého? nebo jiného druhu p?i bezprost?edním vysévání po sobě a p?i vysévání v r?zně dlouhých ?asových intervalech s odstupňovanou délkou odpo?ívání zeminy. Pokusy byly prováděny v nádobách naplněných kompostovou zeminou, které byly umístěny na pokusné zahradě. Byl hodnocen r?st p?edplodiny a následné plodiny stanovením su?iny nadzemních ?ástí a ko?en?. Během r?stu následných rostlin byly odebírány vzorky zemin, v nich? byl stanoven obsah fyziologicky p?istupného dusíku, fostoru a draslíku. V?echny ?ty?i pou?ité p?edplodiny p?sobily pr?kazné změny v r?stu následných rostlin. Len a mák pěstované jako p?edplodiny p?sobily na následné rostliny lnu a cukrovky prost?ednictvím p?dních autopatických ?i allelopatických faktor?. Ú?inek ?ita jako p?edplodiny na ?ito a ho??ice na je?men byl méně výrazný. Z výsledk? se nedá v posledních dvou p?ípadech p?ímo usuzovat na p?ítomnost autopatických nebo allelopatických faktor?. P?i bezprost?ední kultivaci následných rostlin v zemině po p?edplodině bez odpo?ívání byla zji?těna jen inhibice r?stu. Pokusy s odstupňovanou délkou odpo?ívání zeminy dávají mo?nost zachytit celou ?kálu r?stových změn následných rostlin od inhibice ke stimulaci. Ú?inek p?edplodiny na následnou plodinu se zna?ně měnil s délkou odpo?ívání zeminy po p?edplodině. Změny r?stu následných rostlin nekorelovaly—kromě pokusu s ?item a ?áste?ně s ho??icí—se změnami v obsahu sledovaných ?ivin, ani s mno?stvím narostlé p?edplodiny.     

Physiological significance of isoprenoids and phenylpropanoids in drought response of Arundinoideae species with contrasting habitats and metabolism

Physiological, biochemical and morpho‐anatomical traits that determine the phenotypic plasticity of plants under drought were tested in two Arundinoideae with contrasting habitats, growth traits and metabolism: the fast‐growing Arundo donax, which also is a strong isoprene emitter, and the slow‐growing Hakonechloa macra that does not invest on isoprene biosynthesis. In control conditions, A. donax displayed not only higher photosynthesis but also higher concentration of carotenoids and lower phenylpropanoid content than H. macra. In drought‐stressed plants, photosynthesis was similarly inhibited in both species, but substantially recovered only in A. donax after rewatering. Decline of photochemical and biochemical parameters, increased concentration of CO₂ inside leaves, and impairment of chloroplast ultrastructure were only observed in H. macra indicating damage of photosynthetic machinery under drought. It is suggested that volatile and non‐volatile isoprenoids produced by A. donax efficiently preserve the chloroplasts from transient drought damage, while H. macra invests on phenylpropanoids that are less efficient in preserving photosynthesis but likely offer better antioxidant protection under prolonged stress.     

Effects of diet and temperature on Morimus funereus larval hemolymph cation concentrations

The effects of diet and different constant temperatures on hemolymph cation concentrations (Na⁺, K⁺, Mg²⁺, Ca²⁺) have been studied in Morimus funereus larvae collected from natural habitat, fed natural (oak or beech bark) or artificial diet, as well as in larvae reared from hatching on an artificial diet. In the hemolymph of larvae maintained under natural conditions Mg²⁺ was dominant, whereas Na⁺ concentration was very low. In their natural diets concentrations of Na⁺ and K⁺ were very low, while those of Ca²⁺ and Mg²⁺ were high. In larvae continuously reared on an artificial diet, hemolymph Mg²⁺ concentration was significantly decreased and Na⁺ concentration increased more than fourfold compared to the results obtained in oak-fed larvae. Na⁺ and K⁺ are the dominant cations in the artificial diet. The concentrations of K⁺ and Ca²⁺ in the hemolymph of larvae fed natural or artificial diet are nearly identical, suggesting the existence of an internal regulatory mechanism in this insect for these cations. The hemolymph cation concentrations of M. funereus larvae are predominantly dependent upon the diet consumed, much less upon the environmental temperatures. The most stable concentrations of cations were observed in larvae continuously fed an artificial diet and exposed to different constant temperatures. There was much less stability in the hemolymph cation concentration in oak larvae fed either natural or artificial food after their transfer to constant temperatures. With respect to the response to the external factors studied, the most sensitive are the Na⁺ concentrations, the most stable seems to be K⁺. © 1992 Wiley-Liss, Inc.     

Removing Contamination-Induced Reconstruction Artifacts from Cryo-electron Tomograms

Imaging of fully hydrated, vitrified biological samples by electron tomography yields structural information about cellular protein complexes in situ. Here we present a computational procedure that removes artifacts of three-dimensional reconstruction caused by contamination present in samples during imaging by electron microscopy. Applying the procedure to phantom data and electron tomograms of cellular samples significantly improved the resolution and the interpretability of tomograms. Artifacts caused by surface contamination associated with thinning by focused ion beam, as well as those arising from gold fiducial markers and from common, lower contrast contamination, could be removed. Our procedure is widely applicable and is especially suited for applications that strive to reach a higher resolution and involve the use of recently developed, state-of-the-art instrumentation.     

Structural basis for VIPP1 oligomerization and maintenance of thylakoid membrane integrity

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Meiotic studies in two infertile males with autosomal translocations

Summary Meiotic studies were performed in two infertile male carriers of balanced reciprocal translocations between chromosomes 3;5 and 6;10. The first patient had severe oligozoospermia with all stages of meiosis present. The other patient was azzospermic with meiotic breakdown after the first meiotic division. A ring quadrivalent configuration was found in diakinesis in both cases.     

The analogs of oxytocin and D-homoarginine vasopressin with bulky substituted phenylalanine in position 2

Summary Solid phase technique on p-methylbenzhydrylamine resin was used for the synthesis of eight analogs of oxytocin and 8-D-homoarginine vasopressin with the non-coded amino acids L- or D-2,3,4,5,6-pentamethylphenylalanine and L- or D-4-phenylphenylalanine in position 2. The preparation of the above mentioned non-coded amino acids is described as well. All eight analogs were found to be potent inhibitors of oxytocin activity in the uterotonicin vitro test in the absence of Mg²⁺ ions. In the uterotonic testin vitro in the presence of Mg²⁺ and in the testin vivo, their potency is strongly decreased or completely abolished. The substances are also weak pressor inhibitors. The L or D configuration does not seem to influence the activity significantly. Abbreviations: All the chiral amino acids unless otherwise stated are of the L-series. Phe(4-Ph) denotes the 4-phenylphenylalanine, Phe(pentaMe) the 2,3,4,5,6-pentamethylphenylalanine, Har the homoarginine, DMF dimethylformamide, OHBT 1-hydroxybenzotriazole and DCC dicylohexyl-carbodiimitz. The Nomenclature and symbols of the amino acids and peptides obey the published recommendations: IUPAC-IUB Joint Commission on Biochemical Nomenclature: Eur. J. Biochem., 138 (1984) 9.