A dynamic simulation model for powdery mildew epidemics on winter wheat*

A system dynamic model for epidemics of Blumeria graminis (powdery mildew) on wheat was elaborated, based on the interaction between stages of the disease cycle, weather conditions and host characteristics. The model simulates the progress of disease severity, expressed as a percentage of powdered leaf area, on individual leaves, with a time step of one day, as a result of two processes: the growth of fungal colonies already present on the leaves and the appearance of new colonies. By means of mathematical equations, air temperature, vapour pressure deficit, rainfall and wind are used to calculate incubation, latency and sporulation periods, the growth of pathogen colonies, infection and spore survival. Effects of host susceptibility to infection, and of leaf position within the plant canopy, are also included. Model validation was carried out by comparing model outputs with the dynamics of epidemics observed on winter wheat grown at several locations in northern Italy (1991–98). Simulations were performed using meteorological data measured in standard meteorological stations. As there was good agreement between model outputs and actual disease severity, the model can be considered a satisfactory simulator of the effect of environmental conditions on the progress of powdery mildew epidemics.     

Estimating the potential development of Diaporthe helianthi epidemics in Italy*

Diaporthe helianthi is the causal agent of a severe sunflower disease but, in Italy, disease outbreaks are sporadic with no significant losses. The present work investigates the role of meteorological conditions on the potential development of D. helianthi epidemics in Italy, using the French model Asphodel, which simulates the effect of air temperature, relative humidity and rainfall on ascospore maturation and dispersal, infection establishment, disease onset and severity during the period of host susceptibility. Meteorological data measured in eight stations distributed from north to south Italy, over a 5‐year period (1995–99), was used as model input. Results showed that meteorological conditions in Italy are frequently favourable for D. helianthi infections on sunflower, and severe epidemics are possible. Therefore, climatic conditions are not a limiting factor for disease development in the Italian sunflower‐growing areas. The lack of disease epidemics in Italy may be related to differences in the pathogen populations compared with the French ones.     

Cytotoxic capabilities of bovine lymphocytes after lectin stimulation

Bovine peripheral blood mononuclear leukocytes (PBML) were stimulated in vitro with the mitogenic lectins concanavalin A (Con A) and phytohemagglutinin. Their cytotoxic capabilities were evaluated in a 51Cr release assay. Lectin-activated bovine effector cells did not mediate antibody dependent cellular cytotoxicity (ADCC) nor direct killing against cultured tumor target cells. Nevertheless, activation of PBML with lectins consistently generated effector cells able to mediate lectin-dependent cellular cytotoxicity. Cultivation of Con A stimulated-PBML for 3 to 4 weeks in the presence of lymphokines-containing IL-2 generated cells with the ability to mediate lysis without using Con A-coated target cells. However, cytotoxic cultures capable of mediating direct lysis of target cells were not able to mediate ADCC.     

Needle tract implantation after fine needle aspiration biopsy (FNAB) of transitional cell carcinoma of the urinary bladder and adenocarcinoma of the lung

This paper reports three clinical cases of needle tract implantation of neoplastic cells on the abdominal and thoracic wall after ultrasound (US) fine needle aspiration biopsy (FNAB). Primary tumors were two transitional cell carcinomas of the urinary bladder (2 dogs) and one pulmonary adenocarcinoma (1 cat). All three masses grew up along the needle tract. To our knowledge, the seeding of pulmonary adenocarcinoma cells after FNAB on the thoracic wall has never been reported in veterinary medicine.     

Occurrence of Mycobacterium spp. in ornamental fish in Italy

The occurrence of Mycobacterium spp. in freshwater and marine ornamental fish was studied in Italy from June 2002 to May 2005. Two surveys were carried out, one of aquarium fish sent to the Laboratory for diagnosis, and the other of prevalence of infection by mycobacteria in ornamental fish imported into Italy. Bacterial isolation was carried out from the spleen, kidney and liver, and the isolates were subsequently identified by biochemical tests. In the first survey, 387 fish were examined and Mycobacterium spp. were isolated from 181 (46.8%) fish. In the second survey 127 batches of ornamental fish from different countries were examined. Mycobacterium spp. were isolated from 38 (29.9%) batches. The following species were found: M. fortuitum, M. peregrinum, M. chelonae, M. abscessus, M. marinum, M. gordonae, M. nonchromogenicum and M. interjectum. There was a high prevalence of infection independent of the presence of macroscopic lesions. Mycobacterium fortuitum and M. chelonae were more prevalent than M. marinum in the samples examined.     

The sounds of silence: regime shifts impoverish marine soundscapes

Context

Regime shifts are well known for driving penetrating ecological change, yet we do not recognise the consequences of these shifts much beyond species diversity and productivity. Sound represents a multidimensional space that carries decision-making information needed for some dispersing species to locate resources and evaluate their quantity and quality.

Objectives

Here we assessed the effect of regime shifts on marine soundscapes, which we propose has the potential function of strengthening the positive or negative feedbacks that mediate ecosystem shifts.

Methods

We tested whether biologically relevant cues are altered by regime shifts in kelp forests and seagrass systems and how specific such shifted soundscapes are to the type of driver; i.e. local pollution (eutrophication) vs. global change (ocean acidification).

Results

Here, we not only provide the first evidence for regime-shifted soundscapes, but also reveal that the modified cues of shifted ecosystems are similar regardless of spatial scale and type of environmental driver. Importantly, biological sounds can act as functional cues for orientation by dispersing larvae, and observed shifts in soundscape loudness may alter this function.

Conclusions

These results open the question as to whether shifted soundscapes provide a functional role in mediating the positive or negative feedbacks that govern the arrival of species associated with driving change or stasis in ecosystem state.

     

Suppression of feed intake after parenteral administration of D-beta-hydroxybutyrate in pygmy goats

The effect of intraperitoneal injection of D,L- or D-beta-hydroxybutyrate on feed intake and plasma metabolites was investigated in pygmy goats. The combined intraperitoneal injection of D,L-beta-hydroxybutyrate or D-beta-hydroxybutyrate (15 mmol/kg0.75) and 1,3-butanediol (6.6 mmol/kg0.75), a ketogenic substrate, decreased cumulative food intake while the same dose of 1,3-butanediol or DL-beta-hydroxybutyrate alone had no effect. The decrease in food intake after combined injection of D-beta-hydroxybutyrate and 1,3-butanediol was characterized by a significant decrease in meal frequency and a prolongation of the latency to eat. The hypophagic effect of the combined injection of D-beta-hydroxybutyrate and 1,3-butanediol was significant for 8 h, while the hypophagia after D,L-beta-hydroxybutyrate and 1,3-butanediol was significant for only 2 h after injection. Injection of D,L-beta-hydroxybutyrate increased plasma D-beta-hydroxybutyrate levels to 0.55 mmol/l and decreased plasma free fatty acids. Addition of 1,3-butanediol (6.6 mmol/kg0.75) to the injection increased plasma D-beta-hydroxybutyrate level up to 0.75 mmol/l. The results show that parenteral administration of D-hydroxybutyrate reduces feed intake in pygmy goats and that the hypophagia appears to be related to the amount of D-beta-hydroxybutyrate injected. The hypophagia seems to be related to elevated plasma D-beta-hydroxybutyrate concentration, and the threshold concentration appeared to be about 0.7 mmol/l under the experimental conditions of this study.