Solute Accumulation by Grape Pericarp Cells: IV. PERFUSION OF PERICARP APOPLAST VIA THE PEDICEL AND EVIDENCE FOR XYLEM MALFUNCTION IN RIPENING BERRIES

Findlay, N., Oliver, K. J., Nii, N. and Coombe, B. G. 1987.Solute accumulation by grape pericarp cells. IV. Perfusion ofpericarp apoplast via the pedicel and evidence for xylem malfunctionin ripening berries.—J. exp. Bot. 38: 668–679. ¹⁴C-labelled sucrose was applied to freshly-cut pedicels ofexcised unripe and ripening grape berries and let perfuse fordifferent periods; skin and flesh tissues were then extractedand the radioactivity partitioned and measured. Accumulationof radioactivity in a compartmented fraction was greatest inthe skin of unripe berries at the stage when sugar accumulationin vivo was slow. Total radioactivity of parts of berries showedthat activity spread rapidly throughout when the berry was unripebut slowed once ripening commenced. The perfusion of eosin from pedicels was also rapid in unripeberries but in ripe berries it was blocked beyond the pedicelat the outer edge of the 'brush' where the pericarp is aerenchymatousand tanniniferous. The failure of movement through the vascularbundles beyond the brush could not be associated with the developmentof tyloses in tracheary elements; it appeared to be associatedwith stretched tracheids in the network of dorsal vascular bundlesevidenced by irregularities in the spacing of wall thickeningsand breaks in the bounding membranes. This physical disruptionof the tracheary elements of the vascular bundles occurred whenthe berry expands suddenly, about a week after the inceptionof rapid sugar accumulation. The different rates of perfusion limit the utility of the pedicelroute for studies of compartmentation and metabolism in grapeberries at different developmental stages. Nevertheless, therapid compartmentation of radioactivity after pedicel perfusionof unripe skin with ^l4C-labelled sucrose discounts the hypothesisthat the slow rate in skin in situ is due to an apoplastic inhibitor. Key words: Grape berry, accumulation, xylem malfunction     

Population density and intra- and interspecific competition of the African Fish Eagle Haliæeetus vocifer in Kyambura Game Reserve, southwest Uganda

Population density and intra- and interspecific competition of the African Fish Eagle Haliæeetus vocifer were studied in Kyambura Game Reserve, southwest Uganda. Density varied significantly between 1.75 and 3.25 individuals per km of shore for the breeding biotopes along the Kazinga Channel and crater lakes and between 0.45 and 0.58 for unsuitable biotopes such as the Kyambura Gorge or the bush grassland. The age-class distribution showed extremely high percentages of immatures in these unsuitable biotopes (50–95%) as a consequence of intraspecific competition for space and food. Some immatures survived in the bush grassland, feeding on lion and leopard kills and very possibly on birds. Each territory was up to five times larger than breeding pair territories along the Kazinga Channel (5.1 km² in comparison with 0.9 km²). Interspecific competition for space was likely between immature African Fish Eagles and other species of raptors. Ecological segregation with regard to space was assessed between these species in the bush grassland.     

Do landscape health indices reflect arthropod biodiversity status in the eucalypt woodlands of eastern Australia?

Ecosystem or landscape health indices are important tools for land managers. While strong predictable relationships between these indices and biotic diversity are often generalized, they are seldom validated. Here we use data from a semi‐arid eastern Australian woodland to examine the relationships between arthropod community structure and two sets of landscape health indicators: landscape function analysis (LFA), and a terrestrial index of ecological integrity based on common vegetation metrics (structure, composition and function; SCF). Hierarchical partitioning revealed that the ability of LFA or SCF to account for variation in arthropod richness was low, with the variable of importance taxon‐dependent. Similarly, multivariate analyses indicated relatively weak and inconsistent relationships between LFA and SCF indices and arthropod assemblage structure. Results obtained for additional habitat attributes commonly used in terrestrial vegetation monitoring were similar. Our study indicates that strong predictable relationships are rarely apparent, particularly for arthropods. This indicates that these indices have limited use as surrogates of arthropod biodiversity. These results are contrary to the past literature, highlighting the need for additional research and the development of a conceptual and empirical framework linking health indices and arthropod biodiversity. This is necessary to further the theoretical and practical application of these measurements in environmental management.     

Cold tolerance in flour beetle species differing in body size and selection temperature

Cold tolerance is an important trait directly related to survival and hence fitness. In the present study, the link is addressed between cold tolerance and body size, which is associated with many key fitness traits, at both the intra‐ and interspecific levels. Specifically, chill coma recovery time, as a metric of cold tolerance, is examined in five related flour beetle species (four of them belonging to the genus Tribolium), two additional Tribolium castaneum Herbst populations selected for higher temperatures, and a mutant showing reduced body size. Recovery times are negatively correlated with the species average body size but not within each species. Females usually recover faster than males, although this difference is significant in only a single species, and is unrelated to body size. Repeating the experimental procedure with the same individuals, after 2 days in isolation with a limited amount of food, results in longer recovery times. Therefore, even if cold acclimation takes place, its influence appears to be diminished by the deleterious effects associated with the experimental procedure. Hence, the findings provide evidence for an association between body size and cold tolerance in the genus Tribolium, with larger species recovering faster from chill than smaller species. By contrast, the smalleyed flour beetle Palorus ratzeburgii Wissmann does not follow this pattern. Additionally, a population of T. castaneum selected for the highest temperature takes longer to recover from chill coma, indicating a trade‐off between cold and heat adaptations and not to a cross‐protection effect, as sometimes demonstrated.     

APPLYING THE FOUR‐PRINCIPLE APPROACH

The four‐principle approach to biomedical ethics is used worldwide by practitioners and researchers alike but it is rather unclear what exactly people do when they apply this approach. Ranking, specification, and balancing vary greatly among different people regarding a particular case. Thus, a sound and coherent applicability of principlism seems somewhat mysterious. What are principlists doing? The article examines the methodological strengths and weaknesses of the applicability of this approach. The most important result is that a sound and comprehensible application of the four principles is additionally ensured by making use of the organizing meta‐principle of common morality, which is the starting point and constraining framework of moral reasoning.