Dynamics of acetylcholinesterase activity recovery in two earthworm species following exposure to ethyl-parathion

In order for cholinesterase (ChE) activity to be used as an effective biomarker in earthworms, the time course of enzyme activity inhibition and recovery must be fully characterized. A laboratory experiment was carried out using parathion as a model organophosphorus pesticide at the recommended dose (1 mg kg⁻¹) and a 10 fold higher dose (10 mg kg⁻¹), on two earthworm species (Allolobophora chlorotica and Aporrectodea caliginosa). ChE activity and weight were measured every week for a 14 day period of exposure to parathion and then for 8 weeks in uncontaminated soil. After 3 days of exposure, the weight of both earthworm species had decreased by 10–15% compared to the control, regardless of the dose used. During the remainder of the exposure period, no differences were observed between the two doses for A. chlorotica; but A. caliginosa showed rapid weight recuperation for the lowest dose applied. After 28 days and over, the control and both exposed species of worms lost similar amounts of weight. ChE inhibition was measured during and after the exposure period. ChE inhibition followed a different time course for the two species investigated. A. chlorotica appeared less sensitive to parathion than A. caliginosa. In this latter species, ChE inhibition was rapid at close to 70% of the control after 3 days, for either dose, and reached 80–90% after 7 days exposure. While A. chlorotica exhibited the same pattern of inhibition for 10 mg kg⁻¹ of parathion, the inhibition process was slower for the recommended dose with 50% inhibition after 7 days of exposure and 70% after 14 days. ChE activity recovery, after transfer to uncontaminated soil, also followed a different pattern for the two species. After exposure to 1 mg kg⁻¹ parathion, ChE activity from A. chlorotica underwent a slow but constant recovery process to regain the control value after 8 weeks in unpolluted conditions. On the other hand, the ChE activity from A. caliginosa remained strongly inhibited. The differential susceptibility to parathion found in this study could be related to differences in the specificity of the total ChE activities between those two species.     

Effect of the three waxy null alleles on enzymes associated to wheat starch granules using proteomic approach

In bread wheat (Triticum aestivum L.), waxy genes are present at three loci (Wx-A1, Wx-B1 and Wx-D1) and are responsible for amylose synthesis in the grain. Near isogenic lines (NILs) of the agronomic cultivar Tremie with either one, two or three waxy null alleles were used to study the genome response to these null alleles through proteomic analysis of starch granule associated proteins of mature grain. Among the 352 spots that were revealed, 86 varied significantly between NILs. The main differences were observed for the granule bound starch synthase (GBSS), product of the waxy genes. A strong relation (R² = 0.94) between the amount of GBSS per gram of starch granule and the amylose quantity in the grain was revealed through quantification of the GBSS in each NIL. The analysis of GBSS quantity for each NIL invalidated the additive hypothesis for the expression of this enzyme in (Wx-A1a Wx-D1a Wx-B1b) (Wx-D1a Wx-B1a Wx-A1b) and the normal form of Tremie. In addition, four proteins identified as inactive GBSS were increased (+144.9%) in the triple null isogenic form compared to the normal form of Tremie. The quantitative variations of the proteins present in starch granules support the idea of regulatory mechanisms between genomes.     

Influence of germination time and temperature on the properties of rye malt and rye malt based worts

The effects of germination time and temperature on the quality of rye malt and worts derived thereof were investigated using Response Surface Methodology. Amylolytic and proteolytic enzyme activities were increased by long germination periods, while β-glucanase activity was not influenced. Total and Soluble Nitrogen content were also not significantly affected by the variations in germination conditions. Free Amino Nitrogen (FAN) was found in higher amounts in worts prepared from rye malts with long germination times. Extract contents were higher in rye malt than in the control barley malt and could be increased by a favourable germination regime, while no such impact on wort fermentability was found. High wort viscosities could be significantly reduced by a long germination period at low temperatures, but were still unacceptably high. The same conditions favoured the development of endoxylanase activity. Arabinoxylan (AX) accumulated during the germination process and their extractability increased. The results suggest that longer germination periods resulted in an increased number of AX molecules with lower molecular mass. Optimal rye malt qualities within the limits of this study were found for a germination time of 144 h at 10 °C, which resulted in an acceptable FAN content and the lowest measured viscosity.     

Differences in transpiration between a forest and an agroforestry tree species in the Sudanian belt

Average population growth in the African Sudanian belt is 3 % per year. This leads to a significant increase in cultivated areas at the expense of fallows and forests. For centuries, rural populations have been practicing agroforestry dominated by Vitellaria paradoxa parklands. We wanted to know whether agroforestry can improve local rainfall recycling as well as forest. We compared transpiration and its seasonal variations between Vitellaria paradoxa, the dominant species in fallows, and Isoberlinia doka, the dominant species in dry forests in the Sudanian belt. The fallow and dry forest we studied are located in northwestern Benin, where average annual rainfall is 1200 mm. Sap flow density (SFD) was measured by transient thermal dissipation, from which tree transpiration was deduced. Transpiration of five trees per species was estimated by taking into account the radial profile of SFD. The effect of the species and of the season on transpiration was tested with a generalized linear mixed model. Over the three-year study period, daily transpiration of the agroforestry trees, V. paradoxa (diameters 8–38 cm) ranged between 4.4 and 26.8 L day^?1 while that of the forest trees, I. doka, (diameters 20–38 cm) ranged from 9.8 to 92.6 L day^?1. Daily transpiration of V. paradoxa was significantly lower (15 %) in the dry season than in the rainy season, whereas daily transpiration by I. doka was significantly higher (13 %) in the dry season than in the rainy season. Our results indicate that the woody cover of agroforestry systems is less efficient in recycling local rainfall than forest cover, not only due to lower tree density but also to species composition.     

Cross-resistance patterns to ACCase-inhibiting herbicides conferred by mutant ACCase isoforms in Alopecurus myosuroides Huds. (black-grass), re-examined at the recommended herbicide field rate

BACKGROUND: Target‐site‐based resistance to acetyl‐CoA carboxylase (ACCase) inhibitors in Alopecurus myosuroides Huds. is essentially due to five substitutions (Isoleucine‐1781‐Leucine, Tryptophan‐2027‐Cysteine, Isoleucine‐2041‐Asparagine, Aspartate‐2078‐Glycine, Glycine‐2096‐Alanine). Recent studies suggested that cross‐resistance patterns associated with each mutation using a seed‐based bioassay may not accurately reflect field resistance. The authors aimed to connect the presence of mutant ACCase isoform(s) in A. myosuroides with resistance to five ACCase inhibitors (fenoxaprop, clodinafop, haloxyfop, cycloxydim, clethodim) sprayed at the recommended field rate. RESULTS: Results from spraying experiments and from seed‐based bioassays were consistent for all mutant isoforms except the most widespread, Leucine‐1781. In spraying experiments, Leucine‐1781 ACCase conferred resistance to clodinafop and haloxyfop. Some plants containing Leucine‐1781 or Alanine‐2096 ACCase, but not all, were also resistant to clethodim. CONCLUSION: Leucine‐1781, Cysteine‐2027, Asparagine‐2041 and Alanine‐2096 ACCases confer resistance to fenoxaprop, clodinafop and haloxyfop at field rates. Leucine‐1781 ACCase also confers resistance to cycloxydim at field rate. Glycine‐2078 ACCase confers resistance to all five herbicides at field rates. Only Glycine‐2078 ACCase confers clethodim resistance under optimal application conditions. It may be that Leucine‐1781 and Alanine‐2096 ACCases may also confer resistance to clethodim in the field if the conditions are not optimal for herbicide efficacy, or at reduced clethodim field rates. Copyright © 2008 Society of Chemical Industry     

Junctional epidermolysis bullosa in two domestic shorthair kittens

This article describes two cases of junctional epidermolysis bullosa in nonrelated kittens. Both cats exhibited pinnal erosions, oral ulcerations and severe onychomadesis. Histopathology, electron microscopy and/or indirect immunoperoxidase revealed subepidermal clefting, with the lamina densa remaining attached to the floor of the vesicles. Indirect immunofluorescence revealed reduced staining for laminin-5 gamma2 subunit in case 1 and beta3 subunit in case 2.     

Improvement and validation of a pea crop growth model to simulate the growth of cultivars infected with Ascochyta blight (<Emphasis Type="Italic">Mycosphaerella pinodes</Emphasis>)

A model simulating the growth of a pea crop infected with Ascochyta blight was improved and validated using 6 spring pea cultivars, all equally susceptible to Ascochyta blight, but differing in architectural features (stem height, branching ability, standing ability). This model takes into account the spatial distribution of the disease, including the contribution of each layer of the canopy to the radiation interception efficiency (RIE) and the radiation use efficiency (RUE) of the crop. The decreasing contribution of each layer due to the disease was estimated by the relationship between the photosynthesis of a layer and its disease score. The effect of disease on photosynthesis was assessed in controlled conditions as a means of evaluating the effect of disease on each cultivar. All cultivars were affected equally. In field conditions, cultivars with different canopy architectures displayed differences in the profile of disease on leaves. Cultivar Aladin reached higher disease levels at the top of the plant. Epidemics affected crop growth, and the cultivars tested differed in the magnitude of the decrease in growth. Observed and simulated data were compared. The disease-coupled crop growth model gave satisfactory predictions of crop growth for the six cultivars tested.     

Allometric scaling of M-mode cardiac measurements in normal adult dogs

Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r2 = .55-.88). Most variables were most closely related to an index of body length, BW(1/3), although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.