Celia Deane-Drummond

The effect of differential root and shoot temperature on the nitrate reductase activity, assayed in vivo and in vitro in roots ofHordeum vulgare (barley)

There was a large increase in nitrate reductase activity (NAR) assayed both in vivo and in vitro in roots of barley plants (cv. Midas_ grown with roots at 10°C and shoots at 20°C, compared with whole plants grown at 20°C. There were diurnal fluctuations in NRA in roots from both treatments, but they were much greater in roots grown at 20°C, where NRA fell to a very low value in the dark period. The diurnal fluctuations in the malate content of the roots were also related to the root growth temperature. Plants with roots grown at the lower temperature had a higher malate content, especially in the dark period where it was 20 times greater than in plants with roots at 20°C. At all times there was a three-fold increase in soluble carbohydrate in cooled roots and diurnal fluctuations were much less pronounced than those of malate. Growth at low temperatures increased the total flux of amino N into the xylem sap and increased the proportion of reduced N in the total N flux. At certain times of day both 10°C- and 20°C-grown roots responded to exogeneous malate by increasing the flux of amino acid into the xylem sap, although this effect was always more pronounced in 20°C-grown roots.

The regulation of sulphate uptake following growth of Pisum sativum L. seedlings in S nutrient limiting conditions. Interaction between nitrate and sulphate transport

Abstract The characteristics of sulphate transport into Pisum sativum L. Feltham First seedlings which had been grown in the presence and absence of a sulphur source ( ± S ) has been investigated. Short term (10 min) 35SO42− influx into seedlings appeared to obey Michaelis-Menten kinetics over the concentration range 0–0.4 mol m−3 with apparent K m = 85 mmol m −3 and V max = 248 nmol g −1 fresh weight (FW) h−1 for the +S treatment and apparent K m = 70 mmol m −3 , and V max = 2500 nmol g −1 FW h−1 for the −S treatment. Biphasic kinetics were obvious in the former case (+S) only. 35SO42− influx into the latter (−S) seedlings was inhibited by external nitrate in the influx medium ( K i = 0.24 mol m −3 ), but seedlings grown in +S conditions were insensitive to nitrate. The stimulation of sulphate influx following growth of the seedlings in −S conditions was confirmed from experiments which measured 35SO42− efflux after loading in 35SO42. Estimates of half times of filling of the cell wall and cytoplasmic phases were 2.5 min and 13–16 min, respectively. The rate of net sulphate uptake ( J ) into seedlings grown in −S conditions rapidly declined over the first hour of resuply of sulphate, while SO42− influx ( I ) increased over the same time, and then gradually declined over the next 2-h. The results are interpreted in terms of a time dependent increase in rate of 35SO42− efflux ( E ). Nitrate stimulated E , but only from seedlings previously grown in −S conditions. The rate of substrate cycling defined as E/I increased following S deprivation.

Genetically modified theology : the religious dimensions of public concerns about agricultural biotechnology.

This is a PDF version of an article published in Studies in Christian Ethics© 2001. The definitive version is available at http://sce.sagepub.com/

CHARACTERISTICS OF (CLO3-)-CL-36 INFLUX INTO NITRATE REDUCTASE DEFICIENT MUTANT-E1 PISUM-SATIVUM SEEDLINGS - EVIDENCE FOR RESTRICTED INDUCTION BY NITRATE COMPARED WITH WILD-TYPE

The characteristics of nitrate uptake into seedlings of Pisum sativum L. cv. Rondo mutant E1 defective for nitrate reductase (NR) and of its parent variety Rondo have been investigated using 36ClO3− as an analogue for nitrate. The apparent Michaelis Menten constants (Km) for 36ClO3− influx measured over 10 min were similar for mutant E1 and the wild type (Wt). There was a 28% increase in 36ClO3− influx into Wt seedlings following nitrate pretreatment but this was not found when mutant seedlings were used. N starvation increased 36ClO3− influx into both mutant and Wt seedlings, and the rate of cycling E/I was also enhanced to a similar extent. The results are discussed in terms of current ideas on the regulation of nitrate uptake and assimilation.

Laudato Si’ and the Natural Sciences: An Assessment of Possibilities and Limits

This article probes the explicit use of the natural sciences in Laudato Si’, examining in particular its engagement with environmental science and modern technologies in the light of Catholic social teaching on the environment and broader theological engagement with ecology. What are the particular philosophical presuppositions and theological emphases that this encyclical brings to its analysis of the natural world and how do they inform its specific engagement with ecology and science? The article analyzes aspects of contemporary scientific discussion that are particularly relevant for the themes of the encyclical and whose inclusion would have made this an even more convincing document. It also highlights specific philosophical, scientific, and conceptual inconsistencies that have arisen as a result of combining different scientific and theological themes.

A substrate cycling model for nitrate uptake by Pisum sativum seedlings: a key to sensitivity of response of net flux to substrate and effectors?

Net nitrate uptake (J) into Pisum sativum L. seedlings has been investigated. J was high initially, but declined with time as NO3 − efflux (E) approached that of NO3 − influx (I). Both I and E were higher in plants which had been grown without N. J could be reversibly and immediately inhibited by 5 mmol m−3 NH4 +, although plants grown in the presence of nitrate were less sensitive. A theoretical model which involves substrate cycling across the plasmalemma is shown to increase the sensitivity to substrate and effectors. It predicts that during growth of Pisum in N free media the cycling rate (E/I) is increased and the sensitivity of net flux of inhibition by NH4 + is highest. The model also provides a means for control of cytoplasmic nitrate pool size [NO3 −]c.

Characteristics of 36ClO3− and 36Cl− uptake into pisum sativum L. seedlings: Limitations and uses of 36ClO3− as an analogue for NO3−

Abstract The characteristics of 36 Cl − influx and 36 ClO 3 − influx into Pisum sativum L. cv. Feltham First seedlings have been investigated. The kinetics of these fluxes at different external substrate concentrations were generated by computer fist to the data, and for 36 Cl − influx apparent V max Cl − and K m Cl − were 1.62 μmol g −1 fresh wt. h −1 and 0.135 mol m −3 , respectively, ( r 2 = 0.90); for 36 ClO 3 − influx apparent V max ClO 3 − and K m ClO 3 − were 15.29 μmol g −1 fresh wt. h −1 and 0.69 mol m −3 respectively ( r 2 = 0.95). When a range of nitrate concentrations were added to 36 ClO 3 − there was no significant difference between NO 3 − or 36 ClO 3 − at low concentrations ( −3 ), but some divergence at higher concentrations. Initial 36 ClO 3 − NO 3 − influx into P. sativum seedlings was higher than that following extended incubation, which approached that of steady state net nitrate uptake. The difference between 36 ClO 3 − NO 3 − influx (I) and net nitrate or 36 ClO 3 − accumulation (J) was used to measure nitrate efflux (E). There was no detectable 36 Cl − efflux when a similar procedure was adopted using 36 Cl − to measure 36 Cl − accumulation. The upper limit for J was set by I, and was stimulated in conditions of N starvation or inoculation with Rhizobium . The rate of substrate cycling (E/I) and the parameter (1 + E/J) were increased in the former case and when a mixed source of N was used in the culture medium. 36 Cl − influx was inhibited by NH 4 + regimes in these experiments. The purported anion blocker diisothiocyanostilbene-2-2′ disulphonate (DIDS) inhibited 36 Cl − influx and 36 ClO 3 − NO 3 − influx, but in the latter case only that ‘induced’ by N-starvation. The results are discussed in terms of current models for nitrate uptake.

Sophia: The Feminine Face of God as a Metaphor for an Ecotheology

afternoons in the ancient Cathedral of Hagia Sophia prior to the first Orthodox Summer School in Theology and Ecology. You may well ask: What has all this to do with feminist theology? Surely Orthodoxy and feminism are diametrically opposed? Such is the rhetoric of much feminist theology today. However, it was through the quiet reflective space I found as I gazed up at the quite magnificent cathedral dedicated to wisdom, that I began to consider in what way this tradition could be relevant to

Some regulatory aspects of [14C]methylamine influx intoPisum sativum L. cv. Feltham First seedlings

Abstract[14C]Methylamine influx intoPisum sativum L. cv. Feltham First seedlings showed Michaelis-Menten-type kinetics with apparentVmax=49.2 μmol·g-1 FW·h-1 and apparentKm=0.51 mM. The competitive interactions between ammonium and methylamine were most obvious when biphasic kinetics were assumed with saturation of the first phase at ∼0.05 mM. The inhibitor constant for ammonium (Ki)=0.027 mM. When [14C]methylamine was used in trace amounts with ammonium added as substrate, the influx of tracer showed Michaelis-Menten-type kinetics with apparentVmax=3.46 μmol·g-1 FW·h-1 and apparentKm=0.15 mM. The initial rate of net ammonium uptake corresponded with that found when [14C]methylamine was used to ‘trace’ ammonium influx. The latter was also stimulated by high pHo and inhibited by nitrate. Ammonium pretreatment±methionine sulphoximine or glutamine pretreatment of the seedlings inhibited subsequent [14C]methylamine influx, while methylamine or asparagine pretreatment stimulated [14C]methylamine influx. There was also a stimulatory effect of prior inoculation withRhizobium. The results are discussed in terms of current models for the regulation of ammonium uptake in plants.

Shadow Sophia in Christological Perspective: The Evolution of Sin and the Redemption of Nature1

Abstract Drawing on animal ethological studies, this article considers the possibility of a form of morality existing in animals and its relationship with human morality. Given this capacity, I argue that first we need to reflect more carefully on human sin and evil in evolutionary terms. Second, I question the adequacy of the traditional divide between “moral” and “natural” evil as well as consider the possibility of anthropogenic evil. Third, I suggest that a theological response to nonhuman morality should include discussion of the atonement, but traditional categories prove inadequate. Fourth, drawing on Sergii Bulgakov, I explore the idea of shadow sophia as representing a multivocal theodicy that is capable of holding together a tapestry of different theological responses to evil. Finally, I discuss the redemption of nature in the light of the foregoing discussion.