Comparative pathogenicity of sexual and asexual spores of Zymoseptoria tritici (septoria tritici blotch) on wheat leaves

Zymoseptoria tritici ascospores and pycnidiospores are considered the main forms of primary and secondary inoculum, respectively, in septoria tritici blotch epidemics. The pathogenicity of the two types of spores of the same genotypic origin were compared through a two‐stage inoculation procedure in controlled conditions. Adult wheat leaves were inoculated with ascospores collected from field sources, yielding 119 lesions; pycnidiospores collected from 12 lesions resulting from these ascospore infections were then used for inoculation. Lesion development was assessed for 5 weeks; latent period, lesion size, and pycnidium density were estimated for different isolates. The latent period was calculated as the maximum likely time elapsed between inoculation and either the appearance of the majority of the sporulating lesions (leaf scale) or the appearance of the first pycnidia (lesion scale). The latent period was significantly longer (c. 60 degree‐days, i.e. 3–4 days) after infection with ascospores than with pycnidiospores. No difference was established for lesion size and density of pycnidia. A comparison with other ascomycete fungi suggested that the difference in latent period might be related to the volume of spores and their ability to cause infection. Fungal growth before the appearance of lesions may be slower after inoculation with an ascospore than with a pycnidiospore. The mean latent period during the very beginning of epidemics, when first lesions are mainly caused by ascospores, may be longer than during spring, when secondary infections are caused by pycnidiospores. Disease models would be improved if these differences were considered.     

Gross morphological features of plexus brachialis in the chinchilla (Chinchilla lanigera)

This study documents the detailed features of the morphological structure and the innervation areas of the plexus brachialis in the chinchilla (Chinchilla lanigera). The animals (5 female and 5 male) were euthanased with ketamine hydrocloride and xylazine hydrocloride combination, 60 mg/kg and 6 mg/kg, respectively. Skin, muscles and nerves were dissected under a stereo-microscope. The brachial plexus of the chinchilla is formed by rami ventrales of C5-C8, T1 and T2, and possesses a single truncus. The subscapular nerve is formed by the rami of the spinal nerves originating from C6 (one thin ramus) and C7 (one thick and 2 thin rami). These nerves innervate the subscapular and teres minor muscles. The long thoracic nerve, before joining with the brachial plexus, obtains branches from C6 and C7 in 5 cadavers (3 male, 2 female), from C7 in 4 cadavers (2 male, 2 female) and from C6-C8 in only 1 female cadaver. These nerves disperse in variable combinations to form the extrinsic and intrinstic named, nerves of the thoracic limb. An undefined nerve branch originates from the rami ventrales of C7, C8 and T1 spinal nerves enter the coracobrachial muscle.     

Seasonal changes of maximum daily shrinkage reference equations for irrigation scheduling in olive trees: Influence of fruit load

Maximum daily shrinkage (MDS) is the parameter of daily cycle of trunk diameter most widely suggested in irrigation scheduling for several fruit trees. However, as in other plant-measured approaches, the irrigation decision may be difficult due to the influence of the environment on the values obtained. Reference equations of MDS have been established in order to avoid the effects of environmental conditions. Such equations are usually related to simple meteorological data, in order to easily estimate MDS values in full-irrigated conditions. This paper studies the influence of fruit load and the inter-annual variations on the reference equation of MDS in olive trees. These reference equations were calculated during 4 seasons in a full-irrigated orchard and the equations were validated with the data from a different season. The MDS values were related to vapour pressure deficit (VPD) and temperature taken near the experimental orchard. In addition, meteorological data were considered as mean daily or as midday values; only for temperature was the maximum daily value also used. The validation of the equations was made using the fits with all the meteorological data considered (midday and mean daily of VPD and temperature). In addition, two different fits were used in each meteorological data—one according to fruit load and other with the complete pool of data. The equations fit were significantly different each season in all the meteorological data considered. However, seasons with similar fruit load were more similar to each other. In both meteorological data considered (VPD and temperature) the midday values improved the fit in respect to mean daily values. The equations obtained with maximum daily temperature were similar in accuracy to the one of midday. The reference equations in which temperature was used obtained a better fit that the ones calculated with VPD. No significant differences were found in the validation when equations according to fruit load or the complete pool data were compared. The limitations and usefulness of these reference equations are also discussed.     

Associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus, antibodies against bovine viral diarrhea virus, or antibodies against infectious bovine rhinotracheitis virus in calves

OBJECTIVE: To measure associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus (BVDV), antibodies against BVDV, or antibodies against infectious bovine rhinotracheitis (IBR) virus in calves. ANIMALS: 1,782 calves from 61 beef herds. PROCEDURES: Calf serum samples were analyzed at weaning for antibodies against type 1 and type 2 BVDV and IBR virus. Skin biopsy specimens from 5,704 weaned calves were tested immunohistochemically to identify persistently infected (PI) calves. Herd production records and individual calf treatment and weaning weight records were collected. RESULTS: There was no association between the proportion of calves with antibodies against BVDV or IBR virus and herd prevalence of abortion, stillbirth, calf death, or nonpregnancy. Calf death risk was higher in herds in which a PI calf was detected, and PI calves were more likely to be treated and typically weighed substantially less than herdmates at weaning. Calves with high antibody titers suggesting exposure to BVDV typically weighed less than calves that had no evidence of exposure. CONCLUSIONS AND CLINICAL RELEVANCE: BVDV infection, as indicated by the presence of PI calves and serologic evidence of infection in weaned calves, appeared to have the most substantial effect on productivity because of higher calf death risk and treatment risk and lower calf weaning weight.     

Role of the “National Reference Centre for Genetically Modified Organisms (GMO) Detection” in the Official Control of Food and Feed

The National Reference Centre for Genetically Modified Organisms (GMO) detection was established in 2002 within the Istituto Zooprofilattico Sperimentale Lazio e Toscana, with the aim of providing scientific and technical support to the National Health System and to the Ministry of Health within the scope of the regulation of GMO use in food and feed.

The recently adopted EU legislation on GMOs (Regulation CE no. 1829/2003 and no. 1830/2003) introduced more rigorous procedures for the authorisation, labelling and analytical control of food and feed consisting, containing or derived from GMOs. The National Reference Centre, besides its institutional tasks as one of the laboratories of the Italian National Health System, collects and analyses data and results of the national official control of GMOs; carries out scientific research aimed at developing, improving, validating and harmonising detection and quantification methods, in cooperation with other scientific institutions, the Community Reference Laboratory and within the European Network of GMOs laboratories (ENGL); collaborates with the Ministry of Health in the definition of control programmes and promotes educational and training initiatives. Objectives defined for 2004–2006, activities in progress and goals already achieved are presented.

     

Labeled avidin-biotin enzyme-linked immunosorbent assay for detecting antibody to infectious laryngotracheitis virus in chickens

A labeled avidin-biotin enzyme-linked immunosorbent assay (LAB-ELISA) for detecting antibody to infectious laryngotracheitis (ILT) virus in chicken sera was developed and compared with ordinary ELISA. Purified ILT virus, biotin-labeled anti-chicken IgG rabbit IgG conjugate, and horseradish-peroxidase-labeled avidin were used in the LAB-ELISA. When sera from farm chickens were tested by serum neutralization (SN) and two kinds of ELISA, the correlation rate between SN and LAB-ELISA was 50/50 (100%), and that between SN and ordinary ELISA was 39/50 (78%). In LAB-ELISA, all of the sera that were antibody-negative by SN had low absorbance (A) values (below 0.05), and the A values were closely correlated with the SN indexes. In ordinary ELISA, however, the sera antibody-negative by SN had various A values ranging from 0.06 to 0.32. LAB-ELISA had much lower nonspecific reactions than ordinary ELISA against sera from ILT-negative chickens, even when chickens were 30 weeks old. ILT antibody production after ILT vaccination could be detected by LAB-ELISA. A values peaked 5 weeks postinoculation and were maintained for 17 weeks.     

Scientific uses of pulsars

The recently discovered celestial sources of pulsed radio energy can be used to test general relativity, to study the solar corona, and to determine the earth's orbit and ephemeris time. The vector positions and transverse velocities of pulsars can be measured with radio interferometers; in combination with pulse-arrival-time data, the distance determination will yield the average interstellar electron density.