The interaction of adriamycin with cardiolipin in model membranes and in various membrane preparations derived from rat liver mitochondria was studied and the results are analyzed in the light of a possible specific interaction between adriamycin and cardiolipin. It was found that adriamycin binds to cardiolipin-containing model membranes with a fixed stoichiometry of two drug molecules per cardiolipin. Furthermore, the extent of drug complexation by mitochondria and mitoplasts (inner membrane plus matrix) is in reasonable agreement with their cardiolipin content. In contrast, adriamycin-binding curves of inner membrane ghosts and submitochondrial particles reveal considerable association to an additional site, presumably RNA. The evidence for the potential importance of RNA as a target comes from experiments on outer membranes and microsomes which both appear to bind substantial amounts of adriamycin. Removal of the major part of the RNA associated with these fractions by EDTA treatment is accompanied by a dramatic reduction of binding capacity. We propose that endogenous RNA present in mitochondria and mitoplasts is not accessible for adriamycin at low concentrations of the drug due to the presence of an intact lipid barrier. This potential site comes to expression in ghosts and submitochondriai particles, due to the absence of an intact lipid bilayer and due to the inside-out orientation of the limiting membrane, respectively. Electron microscopical studies show that adriamycin induces dramatic changes in mitochondrial morphology, similar to the uncoupler-induced effects described by Knoll and Brdiczka (Biochim. Biophys. Acta 733, 102-110 (1983)). Adriamycin has an uncoupling effect on mitochondrial respiration and oxidative phosphorylation. The concentration dependence of this effect correlates with the adriamycin-binding curve for mitochondria which implies that only bound adriamycin actively inhibits respiration.

Aromatase activity was determined in small discrete areas of the brain of the African catfish, Clarias gariepinus, by a radiometric assay. The fore- and midbrain were divided into eighteen 500-microns transverse sections. From these sections several punches (0.3 mg of tissue) were taken and incubated with [19-3H]-androstenedione. The aromatase activity, calculated from the release of tritium label during aromatization, is expressed in pmol mg-1 tissue hour-1. The highest activity (3.7 pmol) was detected in the preoptic region. The more caudally located area tuberalis, including the nucleus lateralis tuberis and the nucleus recessus lateralis, also showed a relatively high activity (2.5 pmol). A similar activity was found in the most rostral part of the telencephalon and the dorsal parts of the mesencephalon, i.e., the tectum opticum and torus semicircularis (2.3 pmol). A moderate aromatase activity was observed in remaining parts of the brain, except the cerebellum and hindbrain, in which aromatase activity was hardly detectable (0.1-0.3 pmol). It is concluded that a high aromatase activity is present in regions known to be involved in the regulation of reproduction. Since both the torus semicircularis and the tectum opticum display a high aromatase activity, it is suggested that also these structures are involved in reproductive processes.

Riparian ecosystems along streams naturally harbour a high plant diversity with many increasingly endangered species. In our current heavily modified and fragmented catchments, many of these species are sensitive to dispersal limitation. Better understanding of riparian plant dispersal pathways is required to predict species (re-)colonization potential and improve success rates of stream and riparian zone conservation and restoration. Dispersal by water (hydrochory) is an important mechanism for longitudinal and lateral dispersal of riparian species. Crucially for recruitment potential, it also influences the elevation along the riparian hydrological gradient where seeds become deposited. Due to the complex interplay between abiotic and biotic factors, however, it remains unclear how exactly patterns in seed deposition are formed. We compared hydrochorous and non-hydrochorous seed deposition, and quantified patterns of seed deposition along the bare substrate of newly created stream riparian gradients. Water levels were monitored and seed deposition was measured with seed traps along the full range of riparian hydrological conditions (from permanently flooded to never flooded). Average seed numbers and species richness were significantly higher in flooded than in non-flooded seed traps (5.7 and 1.5 times higher, respectively). Community-weighted trait means indicated that typically water-dispersed seeds were more dominant in flooded than in non-flooded seed traps and gradually decreased in concentration from the channel to the upland. Moreover, highly buoyant seeds accumulated at the average water line, and clear elevational sorting of non-buoyant seeds occurred within the floodplain. These results establish a critical role of flooding in shaping patterns of seed deposition along the riparian gradient, delivering many seeds of typical riparian species to riparian zones and depositing them at species-specific elevations as influenced by seed traits, suggesting species-specific dispersal pathways. This shows that hydrochory likely has important consequences for riparian vegetation development and that flooding forms a key process for successful restoration.

H ome to ~80% of the world's terrestrial biodiversity (World Bank 2004), forest systems are increasingly under threat from a wide range of anthropogenic pressures (Newbold et al. 2015). Between 2000 and 2012, 2.3 million km 2 of forest was lost globally (Hansen et al. 2013), and up to 70% of the remaining forest area worldwide is estimated to be within only a single kilometer of forest edges (Haddad et al. 2015). Habitat loss and fragmentation are major drivers of biodiversity loss, with disproportionate species declines in small, isolated fragments (Lees and Peres 2006;Bregman et al. 2014;Keinath et al. 2017). Protected areas (PAs) are increasingly being implemented as a tool to conserve species and maintain associated ecosystem services. As a result, PA coverage has almost doubled over the past 30 years, from ~8.2% of terrestrial land surfaces in 1990 to 15% in 2020 (UNEP-WCMC and IUCN 2020), although coverage still falls short of the Convention on Biological Diversity's Aichi Biodiversity Target of 17%. However, to what extent PAs are an effective conservation measure in landscapes where natural habitat types have become fragmented and are under growing pressure of human activities (hereafter "fragmented landscapes") remains unclear.Several global studies on PA performance have demonstrated the importance of protection status of relatively large and pristine areas for conservation (

Estrogen-2-hydroxylase activity, involved in the biosynthesis of catecholestrogens, was localized in the brain of the male African catfish, Clarias gariepinus, by means of a radiometric assay using [2-3H]estradiol as substrate. Fore-and midbrain were divided in 18, SOO+m thick, transverse sections from which small defined areas were punched out and assayed. The estrogen-2-hydroxylase activity was calculated from the release of tritium during hydroxylation, and expressed in femtomole catecholestradiol . milligram-'tissue . hour-'. The enzyme could be demonstrated throughout the brain. A high activity (>350 fmol) was observed in the telencephalon, in particularly the rostra1 part and the area ventralis pars dorsalis; in the diencephalon in the preoptic region, including the magnocellular part of the preoptic nucleus and the rostra1 part of the anterior periventricular nucleus; and in the area tuberalis, including the nucleus lateralis tuberis, the rostra1 part of the nucleus anterior tuberis, the caudal part of the nucleus posterior periventricularis, and in the nucleus recessus posterioris. Also a high activity was detected in the mesencephalic tectum opticum and the dorsolateral part of the torus semicircularis. The ventral mesencephalon showed a moderate (200-350 fmol) to low (<200 fmol) activity, whereas the lowest activity was found in the hindbrain (118 fmol). The significance of the biosynthesis of catecholestrogens in the brain is discussed in light of the negative feedback mechanism of gonadal steroids on gonadotropin release.