Modeling cold curing of Pierce's disease in Vitis vinifera 'Pinot Noir' and 'Cabernet Sauvignon' grapevines in California

Pierce's disease (PD) of Vitis vinifera grapevines is caused by the bacterium Xylella fastidiosa, a pathogen with a wide plant host range. Exposure of X. fastidiosa-infected plant tissue to cold temperatures has been shown to be effective at eliminating the pathogen from some plant hosts such as grapevines. This "cold curing" phenomenon suggests itself as a potential method for disease management and perhaps control. We investigated cold therapy of PD-affected 'Pinot Noir' and 'Cabernet Sauvignon' grapevine. In the fall, inoculated plants and controls of each cultivar were transported to each of four field sites in California (Foresthill, McLaughlin, Hopland, and Davis) that differed in the magnitude of cold winter temperatures. A model for progression of the elimination of plant disease in relation to temperature was conceptualized to be a temperature-duration effect, where temperatures below a particular threshold kill X. fastidiosa with increasing efficacy as the temperature decreases to some value <6?C. The temperature effect was modeled as a likelihood of a particular temperature killing the pathogen and is termed the ?killing index?. We developed a mathematical model for cold curing of grapevines inoculated with X. fastidiosa and calibrated the model with cold-curing data collected in a field study. Parameter estimation resulted in lowest sum of squared differences across all 10 trials to be low temperature below which the organism is killed (T(0)) = 6°C, number of hours to achieve 100% cure (N(100)) = 195 h, number of hours to achieve 10% cure (N(10)) = 20 h, and killing index (K(x)) = 0.45 for Pinot Noir and T(0) = 6°C, N(100) = 302 h, N(10) = 170 h, and K(x) = 0.41 for Cabernet Sauvignon. With the parameter estimates optimized by model calibration, the simulation model was effective at predicting cold curing in four locations during the experiment, although there were some differences between Hopland for Pinot Noir and Davis for Cabernet Sauvignon. Using historical temperature data, the model accurately predicted the known severity of PD in other grape-growing regions of California, suggesting that it may have utility in assessing the relative risk of developing PD in proposed new vineyard sites.     

An Ultrasonographic Method to Study Reproductive Seasonality in Ewes Isolated from Rams

In studies concerning the seasonality in sheep, the effect of the teaser-ram, which can by itself induce oestrus as well as the development of ovary function bodies, has not been considered. In this study, a method is developed to determine ovarian activity during the year while excluding a possible influence of the ram. The study was carried out on 10 German Blackhead Mutton ewes (GBM) and 10 German Mutton Merino ewes (GMM) and lasted for 14 months. The ewes were kept without contact with any ram, and once a week a transrectal ultrasonography was conducted to determine ovary function bodies (corpora lutea, follicles) and a blood sample was taken to analyse progesterone (P4) concentration. In both breeds, the number of ovulating ewes, the ovulation rate (OR), the size of the corpora lutea (CL) and P4-concentrations showed significant seasonal fluctuations. During the main breeding period (September-February), the OR was higher (2.0 +/- 0.4) than during the rest of the year (1.6 +/- 0.5). Outside the main breeding season (March-August), approximately 40% GBM ewes and only approximately 15% GMM ewes produced CL. The cycle and the related seasonal changes in the P4-concentration coincide with different ultrasonically diagnosed CL (developing or regressing, insufficient, no CL). Between the volume of fully developed CL and P4-concentration, correlations of 0.57 (GMM) and 0.45 (GBM), respectively, were found. On average, P4-concentration in September to February was by approximately 1.60-1.66 nmol/l in the GMM and by approximately 1.80-1.86 nmol/l in the GBM higher than in spring and summer. Considering the OR, the P4-values corresponded with the CL volumes, i.e. in the months from August to February the CL values were significantly larger than in the months March to August. The ultrasonic ovarian diagnosis is a useful method to determine the ram-uninfluenced seasonality of reproduction in sheep.     

On the interactions between Fusarium toxin-contaminated wheat and non-starch-polysaccharide hydrolysing enzymes in turkey diets on performance, health and carry-over of deoxynivalenol and zearalenone

1. Diets with increasing proportions of Fusarium toxin-contaminated wheat (0, 170, 340 and 510 g CW/kg) were fed to male turkeys (BUT Big 6) from d 21 to d 56 of age. Each diet was tested with or without a non-starch-polysaccharide (NSP) hydrolysing enzyme preparation. Dietary deoxynivalenol (DON) and zearalenone (ZON) concentrations were successively increased up to approximately 5.4 and 0.04 mg/kg, respectively. 2. Weight gain decreased slightly with increasing proportions of CW, by 1.6, 0.7 and 3.6%, whereas other performance parameters remained unaffected. NSP enzyme supplements to the diets had no influence. 3. The weight of the emptied jejunum plus ileum, relative to live weight, decreased in a dose-related fashion whereby the NSP enzyme exerted an additional weight-decreasing effect. A similar weight-decreasing NSP enzyme effect was noted for heart weights. Activity of glutamate dehydrogenase in serum was significantly increased in groups fed the diets with the highest CW proportion, whereas gamma-glutamyl-transferase remained unaltered. 4. Viscosity in the small intestine was significantly reduced by supplementing the diets with the NSP enzyme. This effect successively decreased with increasing proportions of the CW. 5. Concentrations of DON and of its de-epoxidised metabolite de-epoxy-DON in plasma, liver and breast meat were lower than the detection limits of 2 ng/ml (plasma) and 4 ng/g, respectively, of the applied HPLC method. DON concentration in bile reached up to 13 to 23 ng/ml whereas de-epoxy-DON concentration was lower than 4 ng/ml. 6. ZON or its metabolites were not detectable in plasma, liver or breast meat (detection limits of the HPLC method were 1, 0.5 and 5 ng/g for ZON, alpha-zearalenol (ZOL) and beta-ZOL, respectively). Concentrations of ZON and alpha-ZOL in bile increased with dietary ZON concentration. The mean proportions of ZON, alpha-ZOL and beta-ZOL of the sum of all three metabolites were 19, 77 and 4%, respectively.     

Guadiamar Toxic Flood: Factors that Govern Heavy Metal Distribution in Soils

The remaining soil contamination after the removal of thesludge and the affected topsoil was studied in the northernpart of the Guadiamar river valley affected by the Aznalcóllartoxic spill. The easily soluble (NH₄NO₃-extraction)and the oxidisable fraction (H₂O₂/HNO₃-extraction)were analysed in samples of two calcareous and two non-calcareoussoils. Correlations between soil properties and heavy metal concentrations were tested with special respect to depth distribution. The spatial distributions of the easily soluble and the oxidisable fraction were highly skewed in both examineddepths (0–20 and 20–40 cm). Easily soluble heavymetal concentrations of a high percentage of samples exceededthresholds that have been given in the German soil protectionlaw particularly in the non-calcareous soils. Within the soillayers of the non-calcareous soils, the pH seems to control theeasily soluble concentrations. However no relation between thepH and depth distribution of heavy metals within the profilescould be found. Physical properties, which determine partlypenetration depth of the sludge and soil mixing caused by theremoval may be the more important factors. Accordingly, highheavy metal concentrations are to be expected even in thesubsoils of clayey sites. As heavy metal concentrations in theoxidisable fraction are still high, further oxidationaccompanied by pH lowering has to be expected. Thus, thestudied soils show a significant risk potential of availableheavy metals even after the removal of the sludge.     

Successful Induction of Antisera Against Rabbit Embryos for Isolation of the ICM and Putative Embryonic Stem Cells

In Expt 1, goat antisera against rabbit blastocysts were induced using spleen cell injection and skin-graft for immunosurgical isolation of ICM cells. Goats received rabbit spleen cell suspension (4 × 10⁸ cells/ml) intravenously once a week for three consecutive weeks, plus an additional dose (boost injection) 10 days after the third injection, or a piece of rabbit skin (3 × 3 cm) transplantation. Blood samples were collected starting from the day after the last cell injection for 21 days. Serum was separated, heat inactivated and stored in frozen condition before titre analysis. Results showed that the antisera/antibodies derived by spleen cell injection reached their peak titre 7 days after the last cell injection, compared with 5 days by the skin-grafted group. In Expt 2, morphologically normal blastocysts were collected for isolating ICMs immunosurgically or for direct culture of zona-free whole blastocysts. In both methods, ICM cells started attaching to the feeder layer and outgrowing from the centre portion of the cells on day 3 after the onset of culture. ICM outgrowths increased in size during days 4–5, and most cells differentiated morphologically after day 6. One colony derived from isolated ICM developed into morphologically ES-like cells expressing alkaline phosphatase activity. Our results indicated that both skin-grafting and spleen cell injection were effective inducing antisera against rabbit embryonic cells. More studies are required to optimize the culture system for rabbit ES cells.     

Benzothiadiazole Activates Resistance in Sunflower (Helianthus annuus) to the Root-Parasitic Weed Orobanche cuman

ABSTRACT The study was conducted to evaluate the potential of induced resistance to infestation of sunflower (Helianthus annuus L.) by the parasitic weed Orobanche cumana Wallr. Treatment of sunflower seeds with 40 ppm of benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) for 36 h completely prevented infection in root chambers. In pot studies using 2.86 x 10(-4) g of Orobanche seeds per gram of soil as inoculum, the total number of O. cumana shoots was reduced by 84 and 95% in the 60-ppm BTH treatment in the first and second trial, respectively. Evaluation of the disease incidences revealed that attachment of O. cumana at the sunflower root and the stage of early penetration was reduced in the BTH-treated plants. Chemical analysis of root extracts revealed synthesis of the phytoalexin scopoletin and of hydrogen peroxide in the BTH-treated sunflower roots, but no increase in lignification. Western blot analysis demonstrated accumulation of the pathogenesis-related protein chitinase in roots and stems of induced resistant plants. These results show that the phenomenon of induced resistance is not restricted to viral, bacterial, and fungal disease and demonstrate the great potential of this protection strategy as an effective component of future plant production systems.     

Effects of Fusarium toxin-contaminated wheat grain on nutrient turnover, microbial protein synthesis and metabolism of deoxynivalenol and zearalenone in the rumen of dairy cows

The aim of the present study was to examine the effects of feeding Fusarium toxin-contaminated wheat to dairy cows on nutrient utilization in the rumen and on duodenal flow of deoxynivalenol (DON), zearalenone (ZON) and their metabolites. Six dairy cows fitted with a large rumen cannula and a simple T-shaped cannula at the proximal duodenum was used in two experiments. The experiments included a control period in which the uncontaminated control wheat was fed and a period in which the control wheat was replaced by the Fusarium toxin-contaminated wheat (8.05 and 7.15 mg DON/kg and 0.26 and 0.1 mg ZON/kg in Expts 1 and 2 respectively). The wheat portion of the daily ration amounted to 50% on a dry matter (DM) basis and rations were completed with hay or grass silage. Five of the six cows were non-lactating and the total daily DM-intake ranged between 4 and 12 kg. The pH-values and the concentration of volatile fatty acids in ruminal fluid were not significantly influenced by feeding the contaminated wheat. In contrast, the postprandial ammonia concentration was consistently higher when the mycotoxin-contaminated wheat was fed. Moreover, the flow of microbial protein and utilizable protein at the duodenum were reduced at the same time. The concentrations of DON and ZON and of their metabolites in freeze-dried duodenal digesta were either not detectable or negligible during the control periods whereas distinct concentrations were measured during the periods where the contaminated wheat was fed. DON was nearly completely metabolized to de-epoxy-DON and the flow at the duodenum ranged between 4% and 28% of DON-intake. The ZON metabolites alpha-zearalenol (ZOL) and beta-ZOL were recovered at the duodenum beside the parent toxin ZON. Their recovery as a percentage of ZON-intake ranged between 43% and 132%. In conclusion, feeding of Fusarium toxin-contaminated wheat altered the ruminal protein utilization. The question of whether this effect was a result of the mycotoxin being present in the rumen or of Fusarium growth-related structural (cell wall) changes of the wheat grain needs to be clarified. The low recovery of DON at the duodenum would indicate either a nearly complete degradation of the molecule in the rumen or an absorption by the mucosa of the rumen, whereas the higher ZON recovery would suggest a lower degradation of the parent toxin in the rumen and/or recovery of some bile-originating entero-hepatic cycling ZON/metabolites.     

The efficacy of a modified aluminosilicate as a detoxifying agent in Fusarium toxin contaminated maize containing diets for piglets

Two feeding experiments with female weaned piglets were carried out applying a complete two by two factorial design to investigate the effects of the dietary inclusion of 500 g/kg Fusarium toxin contaminated maize (8.6 mg/kg deoxynivalenol (DON); 1.2 mg/kg zearalenone (ZON)) and of 4 g/kg aluminosilicate (AS) as a detoxifying agent. The resulting four diets were fed ad libitum to a total of 80 piglets (20 piglets per group, allotted to a total of 20 pens) covering a live weight range of 10.5 +/- 1.3 to 27.5 +/- 4.4 kg in experiment 1, and to a total of 48 piglets (12 piglets per group, allotted to 12 pens) covering a live weight range of 9.7 +/- 1.8 to 21.4 +/- 4.8 kg in experiment 2. The animals of experiment 1 were slaughtered on days 34-36 of feeding the experimental diets. The mycotoxin analyses revealed that the control maize also contained considerable concentrations of Fusarium toxins, but the differences in DON and ZON concentrations between control and contaminated diets were sufficiently high to demonstrate both dose-related toxin effects. Voluntary feed intake and live weight gain of the animals were significantly reduced by the inclusion of Fusarium toxin contaminated maize into the diets in both experiments, while a significantly decreased feed to gain ratio was found in experiment 1. Furthermore, the relative weight of the uterus, stomach and heart of the animals fed the contaminated maize containing diets were significantly increased. Serum albumin concentrations and the activity of GLDH were significantly reduced by the inclusion of the contaminated maize. The addition of AS to the Fusarium toxin contaminated diets did not prevent or alleviate any of the mentioned effects. Moreover, the feed intake tended to be decreased by this supplementation in both experiments, while a significantly decreased feed to gain ratio was indicated for this factor in experiment one as well. The serum concentration of albumin and the activities of ASAT and gammaGT were significantly increased if AS was present in the diets while serum concentration of cholesterol and alpha-tocopherol were decreased significantly or in tendency, respectively. The concentrations of retinol and retinyl esters in liver and serum were not altered by the treatments. The analysed concentrations of zearalenone (ZON) and its metabolites in the bile fluid clearly indicated the differences in dietary ZON concentrations and showed that AS was ineffective in preventing the absorption of the toxin from the gastrointestinal tract. Also, serum concentrations of DON reflected the DON intake prior to sampling. However, there were no differences between groups fed diets with or without AS which also suggests the inefficacy of the tested AS in preventing the DON absorption. The present investigations failed to demonstrate a detoxifying capacity of the tested additive and emphasize the general necessity for a critical verification of detoxifying agents in vivo.     

The influence of the ovulation rate on ultrasonically determined ovine corpus luteum morphometry and progesterone concentrations in cyclic and early pregnant sheep

The objective of the present study was to describe morphology and function of the Corpora lutea (CL) during the oestrous cycle and early pregnancy in sheep with different ovulation rates. In total 40 Booroola. Mutton Merino crosses [heterozygous carriers (FecBFec+) and non-carriers (Fec+Fec+) of the Booroola-fecundity gene (FecB)] with ovulation rates 1 to 4 were examined. During the oestrous cycle (n = 20) and the first month of pregnancy (n = 20) blood samples were taken daily (radioimmunoassay of progesterone) and an ultrasonic ovary diagnosis was conducted. The ewes were scanned transrectally with a 7.5 MHz linear probe lying in a dorsal position. During every examination the CL could be detected. The number and the diameter of the CL were documented and the total volume of luteal tissue per ewe was calculated. The effect of the ovulation rate on CL-morphology (diameter and total volume of luteal tissue per ewe) and peripheral progesterone concentrations were assessed by one-way ANOVA. On day 6 and 7 post ovulationem in cyclic and early pregnant sheep 42% of the diagnosed CL had a cavity. On day 11 (cyclic sheep) and day 10 post ovulationem (early pregnant sheep) this number decreased to 22% (p < 0.05). Both conditions of the CL (compact or with a central cavity) are similar in function and should be regarded as appearances of the same basic process. From the third day onwards the ovulation rate influenced significantly (p < 0.05) the development of the outside diameters of the CL. However, the ovulation rate had no effect on the total volume of the luteal tissue per sheep and on the progesterone concentrations. Yet, in sheep with the ovulation rate 1 significantly lower progesterone concentrations were determined than in sheep with the ovulation rates 2 to 4. In sheep with the ovulation rates 2 to 4 the peripheral progesterone concentrations did not differ significantly. In cyclic and pregnant sheep there is a positive correlation (r = 0.75, p < 0.05) between the progesterone concentration and the total volume of luteal tissue. Considering the smaller diameters of the preovulatory follicles it seems that the development of the CL continues until a threshold-value of progesterone and/or of the total luteal tissue is exceeded. Ewes with low ovulation rates reach this threshold-value with only a few but large CL. With increasing ovulation rate the CL tend to have smaller diameters.