Glucosinolate-accumulating S-cells in Arabidopsis leaves and flower stalks undergo programmed cell death at early stages of differentiation

Plant secondary metabolites glucosinolates (GSL) have important functions in plant resistance to herbivores and pathogens. We identified all major GSL that are accumulated in S-cells in Arabidopsis by MALDI-TOF MS, and estimated by LC-MS that the total GSL concentration in these cells is above 130 mM. The precise locations of the S-cells outside phloem bundles in rosette and cauline leaves and in flower stalks were visualised using sulphur mapping by cryo-SEM/EDX. S-cells contain up to 40% of total sulphur in flower stalk tissues. S-cells in emerging flower stalks and developing leaf tissues show typical signs of Programmed Cell Death (PCD) or apoptosis, such as chromatin condensation in the nucleus and blebbing of the membranes. TUNEL staining for DNA double strand breaks confirmed PCD in S-cells in postmeristematic tissues in the flower stalk as well as in the leaf. Our results show that S-cells in postmeristematic tissues proceed to an extreme degree of metabolic specialisation besides PCD. Accumulation and maintenance of a high concentration of GSL in these cells are accompanied by degradation of a number of cell organelles. The substantial changes in the cell composition during S-cell differentiation indicate the importance of this particular GSL-based phloem defence system. The specific anatomy of the S-cells and ability to accumulate specialised secondary metabolites is similar to that of the non-articulated laticifer cells in latex plants and thus indicates a common evolutionary origin.

The influence of time on lead toxicity and bioaccumulation determined by the OECD earthworm toxicity test

Internationally agreed standard protocols for assessing chemical toxicity of contaminants in soil to worms assume that the test soil does not need to equilibrate with the chemical to be tested prior to the addition of the test organisms and that the chemical will exert any toxic effect upon the test organism within 28 days. Three experiments were carried out to investigate these assumptions. The first experiment was a standard toxicity test where lead nitrate was added to a soil in solution to give a range of concentrations. The mortality of the worms and the concentration of lead in the survivors were determined. The LC(50)s for 14 and 28 days were 5311 and 5395 mug(Pb) g(soil)(-1) respectively. The second experiment was a timed lead accumulation study with worms cultivated in soil containing either 3000 or 5000 mug(Pb) g(soil)(-1). The concentration of lead in the worms was determined at various sampling times. Uptake at so' Sol both concentrations was linear with time. Worms in the 5000 mug g(-1) soil accumulated lead at a faster rate (3.16 mug Pb g(tissue)(-1) day(-1)) tiss than those in the 3000 mug g(-1) soil (2.21 mug Pb-tissue g(-1) day(-1)). The third experiment was a timed experiment with worms cultivated in tiss soil containing 7000 mugPb g(soil)(-1). Soil and lead nitrate solution were mixed and stored at 20 degreesC. Worms were added at various times over a 35-day period. The time to death increased from 23 h, when worms were added directly after the lead was added to the soil, to 67 It when worms were added after the soil had equilibrated with the lead for 35 days. In artificially Pb-amended soils the worms accumulate Pb over the duration of their exposure to the Pb. Thus time limited toxicity tests may be terminated before worm body load has reached a toxic level. This could result in under-estimates of the toxicity of Pb to worms. As the equilibration time of artificially amended Pb-bearing soils increases the bioavailability of Pb decreases. Thus addition of worms shortly after addition of Pb to soils may result in the over-estimate of Pb toxicity to worms. The current OECD acute worm toxicity test fails to take these two phenomena into account thereby reducing the environmental relevance of the contaminant toxicities it is used to calculate. (C) 2002 Elsevier Science Ltd. All rights reserved.

A traitor's death? The identity of a drawn, hanged and quartered man from Hulton Abbey, Staffordshire

Analysis of a set of bones redeposited in a medieval abbey graveyard showed that the individual had been beheaded and chopped up, and this in turn suggested one of England's more gruesome I execution practices. Since quartering was generally reserved for the infamous, the author attempts to track down the victim and proposes him to be Hugh Despenser, the lover of King Edward II.

Modelling seasonally varying data: A case study for sudden infant death syndrome (SIDS)

Many time series are measured monthly, either as averages or totals, and such data often exhibit seasonal variability-the values of the series are consistently larger for some months of the year than for others. A typical series of this type is the number of deaths each month attributed to SIDS (Sudden Infant Death Syndrome). Seasonality can be modelled in a number of ways. This paper describes and discusses various methods for modelling seasonality in SIDS data, though much of the discussion is relevant to other seasonally varying data. There are two main approaches, either fitting a circular probability distribution to the data, or using regression-based techniques to model the mean seasonal behaviour. Both are discussed in this paper.

Life and death in a civitas capital: metabolic disease and trauma in the children from late Roman Dorchester, Dorset

The impact that “Romanization” and the development of urban centers had on the health of the Romano-British population is little understood. A re-examination of the skeletal remains of 364 nonadults from the civitas capital at Roman Dorchester (Durnovaria) in Dorset was carried out to measure the health of the children living in this small urban area. The cemetery population was divided into two groups; the first buried their dead organized within an east–west alignment with possible Christian-style graves, and the second with more varied “pagan” graves, aligned north–south. A higher prevalence of malnutrition and trauma was evident in the children from Dorchester than in any other published Romano-British group, with levels similar to those seen in postmedieval industrial communities. Cribra orbitalia was present in 38.5% of the children, with rickets and/or scurvy at 11.2%. Twelve children displayed fractures of the ribs, with 50% of cases associated with rickets and/or scurvy, suggesting that rib fractures should be considered during the diagnosis of these conditions. The high prevalence of anemia, rickets, and scurvy in the Poundbury children, and especially the infants, indicates that this community may have adopted child-rearing practices that involved fasting the newborn, a poor quality weaning diet, and swaddling, leading to general malnutrition and inadequate exposure to sunlight. The Pagan group showed no evidence of scurvy or rib fractures, indicating difference in religious and child-rearing practices but that both burial groups were equally susceptible to rickets and anemia suggests a shared poor standard of living in this urban environment.