CONTINUING THE DEFINITION OF DEATH DEBATE: THE REPORT OF THE PRESIDENT'S COUNCIL ON BIOETHICS ON CONTROVERSIES IN THE DETERMINATION OF DEATH

The President's Council on Bioethics has recently released a report supportive of the continued use of brain death as a criterion for human death. The Council's conclusions were based on a conception of life that stressed external work as the fundamental marker of organismic life. With respect to human life, it is spontaneous respiration in particular that indicates an ability to interact with the external environment, and so indicates the presence of life. Conversely, irreversible apnoea marks an inability to carry out the necessary work of life, an inability which the Council considers an indicator of death. This conception has been conceived to circumvent criticisms of the previous model of loss of somatic integration, a model the Council admits that, in the presence of evidence of continuing functional integration in brain dead patients, was looking less than convincing. Nevertheless, by focusing on external work and ignoring the more essential work of integrative unity, the Council's conception of the nature of life is untenable, and of no assistance in supporting a relation of equivalence between the concepts of brain death and death. Consequently, the Council's conclusions do little to advance the definition of death debate, a potentially intractable debate that may necessitate the investigation of alternate ethical justifications for organ harvesting.     

Histone or Bacterial Basic Protein required for Replication of Bacteriophage RNA

IN spite of the apparent simplicity of RNA bacteriophage, several proteins, both phage and bacterial, are required for the synthesis of Qβ RNA in vitro. The polymerase complex alone contains one phage-coded and three host proteins^1,2. The specific role of these proteins in Qβ RNA replication is unknown, but because they demonstrate an associative interaction and are always found with active enzyme, it has been suggested that all four contribute to polymerase activity¹.     

The Distribution of Hormones in Relation to Apical Dominance in Brussels Sprouts (Brassica oleracea var. gemmifera L.) Plants

The lateral buds of intact Brussels sprout plants containedless auxin and gibberellin than the main apex. When the apexwas removed the auxin content of the top lateral buds increasedwithin 2 days, but gibberellin activity did not increaseuntilshoot extension was apparent. Auxin application to the cut surfaceof decapitated plants caused lateral bud inhibition, but didnot completely prevent bud growth. Both auxin and gibberellinactivity in the plant apex decreased with increasing age, butonly gibberellin activity decreased in the lateral buds. Theauxin content of the lateral buds on intact plants increasedwith time. It is suggested that in Brussels sprouts, lateral bud inhibitionis due to sub-optimal auxin activity, and that decapitationinduces an auxin increase in these buds which then grow out.Lateral shoots are produced following decapitation of youngplants because the gibberellin content of the lateral buds isrelatively high. Only bud swelling occurs in decapitated olderplants because the gibberellin content of the buds is too lowto stimulate shoot extension. It is concluded that these results support the theory that hormone-inducednutrient diversion may control lateral bud development.     

Patterns of divergence in the olive sunbird Cyanomitra olivacea (Aves: Nectariniidae) across the African rainforest–savanna ecotone

In the debate over modes of vertebrate diversification in tropical rainforests, two competing hypotheses of speciation predominate: those that emphasize the role of geographical isolation during glacial periods and those that stress the role of ecology and diversifying selection across ecotones or environmental gradients. To investigate the relative roles of selection versus isolation in refugia, we contrasted genetic and morphologic divergence of the olive sunbird (Cyanomitra olivacea) at 18 sites (approximately 200 individuals) across the forest–savanna ecotone of Central Africa in a region considered to have harboured three hypothesized refugia during glacial periods. Habitats were characterized using bioclimatic and satellite remote‐sensing data. We found relatively high levels of gene flow between ecotone and forest populations and between refugia. Consistent with a pattern of divergence‐with‐gene‐flow, we found morphological characters to be significantly divergent across the gradient [forest versus ecotone (mean ± SD): wing length 60.47 ± 1.81 mm versus 62.18 ± 1.35 mm; tarsus length 15.51 ± 0.82 mm versus 16.00 ± 0.57 mm; upper mandible length 21.77 ± 1.09 mm versus 23.19 ± 0.98 mm, respectively]. Within‐habitat comparisons across forest and ecotone sites showed no significant differences in morphology. The results show that divergence in morphological traits is tied to environmental variables across the gradient and is occurring despite gene flow. The pattern of divergence‐with‐gene‐flow found is similar to that described for other rainforest species across the gradient. These results suggest that neither refugia, nor isolation‐by‐distance have played a major role in divergence in the olive sunbird, although ecological differences along the forest and savanna ecotone may impose significant selection pressures on the phenotype and potentially be important in diversification. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 821–835.     

Effects of earthworms, nematodes, cultivations and host plants on Verticillium wilt of peach and cherry

Verticillium dahliae but not V. albo-atrum Berth was isolated from eight out of twenty-one stone fruit orchards surveyed for Verticillium wilt disease in western New York. Wilt incidence was related to the cultivation of tomato or legumes as previous or inter-crop with stone fruit trees. A limited cross species inoculation using isolates of V. albo-atrum and V. dahliae from woody and herbaceous plants showed that peach and cherry were susceptible to both species. The effect of V. dahliae on growth of cherry seedlings in the presence of Tylenchorynchus claytoni, Pratylenchus penetrans and Meloidogyne hapla was compared. P. penetrans and M. hapla produced more severe growth reduction than T. claytoni. The adverse effect of Verticillium on the growth of cherry seedlings was greater acting together with any one of the three nematodes than acting alone. V. dahliae was shown to be capable of passage through earthworms without loss of infectivity.     

Distribution of photosynthate produced before and after anthesis in tall and semi-dwarf winter wheat, as affected by nitrogen fertiliser

In 2 years the distribution of radioactivity recovered in entire shoots of field-grown winter wheat was determined at various times after exposing the top two leaves (flag leaf or second leaf) to ¹⁴CO₂ for 30 s. In 1976 when ¹⁴C was supplied to either leaf 14 days before anthesis, 30% was in the ear at anthesis. Less than 5% was in the leaf exposed to ^I4CO₂. The remainder was equally divided between the stem above and below the flag-leaf node when the flag leaf had been exposed, and was mainly in the lower part of the stem when the second leaf had been exposed. By maturity the proportion in the stem had decreased; 20% of the total activity was in the grain and 30% was still in the ear structures. When ¹⁴C was supplied 10 days after anthesis, the proportion in the ear 24 h later ranged from 42 to 69% of that in the whole shoot when the flag leaf was exposed, and from 6 to 28% when the second leaf was exposed. At maturity these proportions increased to 92 and 85% when the ¹⁴C had been supplied to flag leaves and second leaves respectively. When ¹⁴C was supplied 25 days after anthesis to either flag leaves or second leaves, more than 90% of the activity was in the mature ears. Less than 5% of the ¹⁴C remaining at maturity from any treatment was still in the leaf exposed to ¹⁴CO₂. Between 2 and 6% of ¹⁴C supplied after anthesis was in the non-grain parts of the ear. The proportion of the ¹⁴C in the ear was greatest for the semi-dwarf varieties Maris Fundin and Hobbit, less for Maris Huntsman, and least for Cappelle-Desprez. These varietal differences were large 24 h after exposure to ¹⁴CO₂, especially in 1976. They were small and rarely significant at maturity. Nitrogen fertiliser up to 210 kg N ha^-1 had negligible effects on the distribution of ¹⁴C, although it greatly increased growth and yield, especially in 1975.     

Isoperoxidases in Epidermal Layers of Tobacco and Changes during Organ Formation in vitro

The content and pattern of soluble isoperoxidases were determined in epidermal explants taken from different internodes of tobacco plants in the vegetative and floral states. There were qualitative and quantitative differences in the isoperoxidases, with a decrease in content and fewer bands being observed acropetally, i.e., in going from the base of the stem towards the apex. Epidermal explants from floral branches were grown in in vitro culture, with various media moditications, to form de novo floral or vegetative buds, roots or callus. Changes in soluble isoperoxidases were followed electrophoretically in relation to these varying morphogenetic pathways. In each of them, the number of bands increased on both the anodic and cathodic sides with time in culture. Compared to each other these four morphogenetic programmes were different in their peroxidase zymograms, mainly through varying kinetics in the development of activity of the isoenzymes. The changes observed during root and vegetative bud formation agree with previously published data, and the changes during floral bud formation agree with those observed in vivo.     

Seasonal changes in the nutrient content of East African grassland vegetation

Significant seasonal changes in the concentrations of N, P, K, and Ca were observed in the herb layer vegetation at Nairobi National Park and Masai Mara Game Reserve in Kenya. These changes were related to the alternation of wet and dry seasons. Live forbs typically had the highest concentrations of all nutrients, especially N and Ca, at both locations. Standing dead and litter compartments showed less seasonal variation and had the lowest concentrations of all nutrients except Ca when compared with those of other compartments. Standing stocks of all nutrients were higher at Nairobi National Park than at Masai Mara due to larger litter and standing dead compartments resulting from lower grazing intensity and a lower frequency of fire. Most of the aboveground nutrients at Nairobi National Park appeared to be recycled through the decomposer pathway, while a large proportion of the standing stock at Masai Mara appeared to be recycled through the excreta of large mammalian herbivores and through fires. The crude protein content of the live grass compartment fell below maintenance levels required for ruminants (5% crude protein) during September 1980 and February 1981 at Nairobi National Park and during June and July 1980 at Masai Mara Game Reserve. Thus, herbivore populations in these preserves may be limited by shortages of nutritionally adequate food during dry seasons, as previously reported for other regions in East Africa.     

Adenylate energy charge in streambed sediments

SUMMARY.

• 1 The adenylate energy charge (EC_A) of microbial communities from streambed sediments was measured during three different seasons, under experimental manipulation and in culture.
• 2 The EC_A values of sediments (x±S.E.) in the autumn, winter and spring were low and constant; 0.22±0.03 (n=12), 0.32±0.04 (n= 12) and 0.28±0.03 (n=6) respectively.
• 3 A 5 h exposure of sediments to an algal lysate at 3.0–4.0°C and a 48 h exposure of sediments to tryptone-yeast extract at 8.0–18.0°C failed to increase EC_A even though respiration increased 3.7-fold during the latter exposure.
• 4 The cellular EC_A of a bacterial monoculture, sampled in log phase, was 0.90±0.10 (n=3), but cxtracclluhir AMP depressed the total culture EC_A to 0.21±0.01 (n=4).
• 5 Attempts to isolate extracellular AMP from the interstitial waters of sediments were unsuccessful.
• 6 The data suggest that under natural conditions EC_A is of limited use as a monitor of subtle changes in the physiological state of microbial communities in streambed sediments.

     

The importance of pre-thicket conifer plantations for nesting Hen Harriers Circus cyaneus in Ireland

Hen Harriers Circus cyaneus are threatened across much of their range and their conservation requires appropriate habitat management. The locations of 148 Hen Harrier nests found in the Republic of Ireland during national breeding surveys in 2000 and 2005 were used to assess nest-site selection. The distribution of these nests was compared to distributions of randomly located points to investigate selection at the scale of the nest-site and landscape. The main nesting habitats selected were pre-thicket stage of first and, particularly, second rotation plantations, mostly of exotic conifers. There was no evidence that the area of post-closure plantations negatively affected Hen Harrier nest distribution. There was a positive correlation across study areas between changes in numbers of Hen Harrier nests between 2000 and 2005 and changes in the area of pre-thicket second rotation plantations over the same period. The overall effect of plantation forests on breeding Hen Harriers in Ireland therefore appears to be positive. However, this study did not consider the effects of plantation habitats on breeding success. Improved grassland was strongly avoided as a nesting habitat. Furthermore, after controlling for the influence of nesting habitat on nest location, landscapes with a high percentage cover of improved grassland were also avoided. Further agricultural intensification of grassland in areas where Hen Harriers breed is likely to have a negative impact on this species. These results are required for the development of management strategies for the conservation of this species.