Carboxyatractyloside-insensitive influx and efflux of adenine nucleotides in rat liver mitochondria

Unidirectional transport (influx and efflux) of adenine nucleotides in rat liver mitochondria was examined using carboxyatractyloside to inhibit rapid exchange of matrix and external adenine nucleotides via the adenine nucleotide translocase. Influx of adenine nucleotides was concentration-dependent. ATP was the preferred substrate with a Km of 2.67 mM and V of the preferred substrate with a Km of 2.67 mM and V of 8.33 nmol/min/mg of protein. For ADP, the Km was 14.7 mM and V was 10.8 nmol/min/mg of protein. Efflux of adenine nucleotides was also concentration-dependent, varying directly as a function of the matrix adenine nucleotide pool size. Any increase in the influx of adenine nucleotides was coupled to an increase in efflux. However, as the external ATP concentration was increased, influx was stimulated to a much greater extent than was efflux. This imbalance suggested that under certain conditions adenine nucleotide movement might be coupled to the movement of an alternate anion such as phosphate. Adenine nucleotide efflux increased as the external phosphate concentration was varied from 0.5 to 4 mM. Also, increasing the external phosphate concentration caused adenine nucleotide influx to decrease, suggesting competition. In the absence of external adenines and phosphate, no efflux occurred. Both adenine nucleotide influx and efflux were depressed if Mg2+ was omitted. Adenine nucleotide efflux in the presence of external phosphate was inhibited much less by lack of Mg2+ than was efflux in the presence of external ATP. This evidence supports a model in which either adenine nucleotides (probably with Mg2+) or phosphate can move across the mitochondrial membrane on a single carrier. Net adenine nucleotide movements can occur when adenine nucleotide movement is coupled to the movement of phosphate in the opposite direction.     

Variability of quantitative markers of irradiated and non-irradiated fish from experimental populations. II. Changes in the values of some quantitative markers in relation to body length

The influences of a single rtg irradiation dose (14 mGy) on some quantitative signs in dependence on the body length was studied in the experimental fishes Barbus conchonius and B. tetrazona. The values of all followed signs increased positively due to the body length growth. The irradiation with the abovementioned dose in the given conditions had relative small influence on the growth course of the chosen quantitative sign values in the control and irradiated fishes of both species is the same (the regression lines are in good agreement, resp. they are parallel). The statistically significant difference was stated only between the irradiated the non-irradiated groups of B. tetrazona due to the head height (the regression lines are divergent).     

Lebendbeobachtungen zur Struktur des Golgifeldes bei Zellen eines transplantablen Plasmocytoms in vitro

Zusammenfassung Zellen des aus unreifen Plasmoblasten bestehenden, transplantablen KG 13-Plasmocytoms des Goldhamsters zeigen bei phasenoptischer Lebendbeobachtung in vitro ein besonders großes, stark strukturiertes Golgifeld. Dieses wird von einem Saum heller Pinocytosetröpfchen gegen die Speichergranula abgesetzt. Die Form des Golgifeldes, die Gesetzmäßigkeit seiner Veränderungen, die Spezifität seiner Strukturen und seine Beziehung zum Zellkern werden beschrieben. Pinocytosebläschen wandern bei dieser Zellart im gesamten Verlauf sichtbar von der Zellmembran zwischen den Speichergranula hindurch zur Randzone des Golgifeldes und lösen sich dort auf. Die Granula des Cytoplasmas entstehen offenbar im Golgifeld und werden in seiner Randzone erstmalig als solche erkennbar, um ins Cytoplasma zu wandern.

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Summary The KG 13 plasmocytoma from the Syrian golden hamster consists of immature Plasmoblasts. Living cells of this plasmocytoma observed by phase contrast microscopy in the hanging drop in vitro have a particularly large Golgi field surrounded by a border of light pinocytose bubbles. The cytoplasma is filled with storage granules. The form and the modifications of the Golgi field are described as well as his structure and his relations to the nucleus. Pinocytose bubbles reach the border of the Golgi field after crossing granules and disappeare. The granules are evidently formed in the Golgi field and become visible in its periphery.

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Die Arbeit wurde mit Unterstützung durch die Deutsche Forschungsgemeinschaft durchgeführt.     

Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.     

Rhodamine 123 inhibits bioenergetic function in isolated rat liver mitochondria

Rhodamine 123 accumulates in the mitochondria of living cells and exhibits selective anticarcinoma activity. The biochemical basis of toxicity was investigated by testing the effect of the dye on isolated rat liver mitochondria. Much lower concentrations of rhodamine 123 were required to inhibit ADP-stimulated respiration and ATP synthesis in well-coupled energized mitochondria than were required to inhibit uncoupled respiration and uncoupler-stimulated ATP hydrolysis. The amount of rhodamine 123 associated with the mitochondria was several-fold greater under energized as compared to non-energized conditions, which may explain why coupled functions appeared to be more sensitive than uncoupled functions to inhibition at low concentrations of rhodamine 123. It was concluded that the site of rhodamine 123 inhibition is most likely the F0F1 ATPase complex and possibly electron transfer reactions as well.