Expression of garlic leaf lectin under the control of the phloem-specific promoter Asus1 from Arabidopsis thaliana protects tobacco plants against the tobacco aphid (Myzus nicotianae)

BACKGROUND: To check for correlation between the insecticidal properties and the specificity of lectins, a comparative study was made of the insecticidal activities of two garlic lectins with different biological activities.RESULTS: The insecticidal activity of the garlic (Allium sativum L.) leaf lectin ASAL and bulb lectin ASAII towards the tobacco aphid Myzus nicotianae Blackman was studied using bioassays with transgenic tobacco (Nicotiana tabacum L. cv. Wisconsin 38). Bioassays were started with newborn nymphs of the tobacco aphid. Although during the first 7-8 days when nymphs developed to adults there were no apparent effects, part of the nymphal population was found to develop into winged (alate) forms. Later it became clear that transgenic plants expressing ASAL and ASAII had a significant effect on the reproduction capacity of the resulting adults, with a reduction of up to 40%. Different life table parameters such as prereproductive time, intrinsic rate of natural increase, generation time and doubling time were significantly affected (P < 0.05) in aphids grown on transgenic plant material expressing ASAL and ASAII.CONCLUSION: Bioassays with tobacco plants expressing ASAL and ASAII demonstrated a significant impact on the population growth of M. nicotianae. Therefore, both lectins can be considered as valuable candidate aphid control agents.     

Interferon mediated antiviral activity against salmonid fish viruses in BF-2 and other cell lines

Double-stranded RNA and type I interferon-like activity induce an antiviral state in vertebrate cells and in several fish cell lines by increasing the expression of proteins that inhibit virus replication. We compared the protection induced by the polyinosinic:polycytidylic acid (poly I:C) or poly I:C plus transfection agents against the infectious pancreatic necrosis virus (IPNV) and the infectious hematopoietic necrosis virus (IHNV) in BF-2 cells, with that induced in RTG-2, CHSE-214, or SAF cells. In addition, we examined the reduction in the infective titers of these viruses and the correlation with Mx protein expression as IFN marker. Furthermore, the suitability of BF-2 cells for the evaluation and optimization of immune responses in an IPNV-IHNV co-infection was assessed. The results demonstrated strong anti-IPNV and anti-IHNV activity (around 90% of infected cells surviving) in BF-2 cells transfected with poly I:C, in which a loss of 1log(10) or 3log(10) of the IPNV or IHNV infective titers, respectively, was observed. No antiviral activity was evident in the cells incubated with poly I:C alone. The protection recorded in the co-infection experiments was comparable with those of the single infections. The SAF cell line exhibited the lowest antiviral capacity (45%), which was also increased after transfection with poly I:C. In addition, medium from transfected BF-2 provided protection against IPNV (1log(10) loss of infective titer) and IHNV (2log(10) loss of infective titer) in new monolayers, indicating that these cells secreted the factors that induce antiviral activity. A correlation between antiviral activity and Mx protein expression was observed in all the cells. These results indicate that poly I:C transfection could improve IFN-like production in these cell lines. However, the antiviral effectiveness of poly I:C differed between cell lines. On the basis of our findings, we conclude that the BF-2 cell line is a useful model in which to study the role of IFN-induced cytokines in resistance against single or double infections with salmonid fish viruses.     

Risk assessment of bluetongue disease incursion into Germany using geographic information system (GIS)

Using a geographic information system (GIS), by analysis of the relationship between the spatial distribution of cattle density and the risk factors temperature, altitude and rainfall, we defined geographical habitats enabling optimal development and competence of Culicoides spp. to transmit Bluetongue-Virus (BTV): Risk zones (low, high, highest risk) were identified mainly in Baden-Württemberg, Hessen and Rheinland-Pfalz if persistently infected ruminants are imported into these zones in summer (June to August mainly), based on the current climatic conditions, BTD outbreaks are considered a real possibility. Overwintering of the virus seems unlikely. However, global warming will lead to a steady increase of the size of the risk zones. In addition, the possibility of primary outbreaks increases. The reason for this is not only the expected northern shift of Culicoides imicola, but in addition an increasing vector competence of domestic Culicoides species. We therefore recommend the storage of vaccines as well as conducting ecological studies analysing the presence of Culicoides vectors. Using the data from these studies, it will be possible to produce updated quantitative risk assessment via GIS.     

Results of salmonella isolation from poultry products, poultry, poultry environment, and other characteristics

Five hundred sixty-nine Salmonella were isolated out of 4745 samples from poultry products, poultry, and poultry environment in 1999 and 2000 from the Pacific northwest. These Salmonella were identified to their exact source, and some were serogrouped, serotyped, phage typed, and tested for antibiotic sensitivity. Food product samples tested included rinse water of spent hens and broilers and chicken ground meat. Poultry environment samples were hatchery fluff from the hatcheries where eggs of grandparent broiler breeders or parent broiler breeder eggs were hatched and drag swabs from poultry houses. Diagnostic samples were of liver or yolk sac contents collected at necropsy from the young chicks received in the laboratory. Of these samples tested, 569 were Salmonella positive (11.99%). Ninety-two Salmonella were serogrouped with polyvalent somatic antisera A-I and the polymerase chain reaction. Somatic serogroups B and C comprised 95.25% of all the Salmonella. Out of a total of 569 positive samples, 97 isolates of Salmonella were serotyped. A total of 16 serotypes and an unnamed Salmonella belonging to serogroup C1 were identified. The Salmonella serotypes were heidelberg (25.77%); kentucky (21.64%); montevideo (11.34%); hadar and enteritidis (5.15% each); infantis, typhimurium, ohio, and thompson (4.12% each); mbandaka and cerro (3.09% each); senftenberg (2.06%); berta, istanbul, indiana, and saintpaul (1.03% each); and an unnamed monomorphic Salmonella (2.06%). Ninety-two Salmonella were tested for drug sensitivity with nine different antimicrobials. All of the 92 Salmonella were resistant to erythromycin, lincomycin, and penicillin except one sample (S. berta), which was moderately sensitive to penicillin. All of the tested Salmonella were susceptible to sarafloxacin and ceftiofur. The percentages of Salmonella susceptible to sulfamethoxazole-trimethoprim, gentamicin, triple sulfa, and tetracycline were 97.83%, 92.39%, 86.96%, and 82.61%, respectively.     

Influence of lairage time on some welfare and meat quality parameters in pigs

A total of 150 Large White cross Landrace pigs (110-120 kg) of both sexes were used to investigate the effects of three different lairage times (0 h, 3 h, 9 h). Blood samples were collected at exanguination and cortisol, glucose, lactate, muscle enzymes and haematological parameters were determined. Post-mortem measurements of muscle pH were taken at 20 min, 2 h and 24 h from Longissimus thoracis and Semimembranosus. Lairage time showed a significant effect on pH24, internal muscle reflectance using the fibre optic probe (FOP24), red blood cells, neutrophils and lymphocytes, glucose and enzymatic activities. Changes in blood profile and meat quality parameters indicated that three hours of lairage in Spanish commercial conditions may reduce the amount of stress exhibited by pigs at slaughter and better meat quality can be obtained. No lairage or an excessively long lairage period without food may compromise animal welfare and meat quality.     

Comparison of antimicrobial resistance in generic Escherichia coli and Salmonella spp. cultured from identical fecal samples in finishing swine

The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.     

Effects of anesthesia and surgery on serologic responses to vaccination in kittens

OBJECTIVE: To determine the effects of anesthesia and surgery on serologic responses to vaccination in kittens. DESIGN: Prospective controlled trial. ANIMALS: 32 specific-pathogen-free kittens. PROCEDURES: Kittens were assigned to 1 of 4 treatment groups: neutering at 7, 8, or 9 weeks of age or no neutering. All kittens were inoculated with modified-live virus vaccines against feline panleukopenia virus (FPV), feline herpesvirus (FHV), and feline calicivirus (FCV) at 8, 11, and 14 weeks of age and inactivated rabies virus (RV) at 14 weeks of age. Serum antibody titers against FPV, FHV, and FCV were determined at 8, 9, 11, 14, and 17 weeks of age; RV titers were determined at 14 and 17 weeks of age. RESULTS: Serologic responses of kittens neutered at the time of first vaccination (8 weeks) were not different from those of kittens neutered 1 week before (7 weeks) or 1 week after (9 weeks) first vaccination or from those of kittens that were not neutered. In total, 31%, 0%, 69%, and 9% of kittens failed to develop adequate titers against FPV, FCV, FHV, and RV, respectively, by 17 weeks of age. CONCLUSIONS AND CLINICAL RELEVANCE: Neutering at or near the time of first vaccination with a modified-live virus vaccine did not impair antibody responses in kittens. Many kittens that were last vaccinated at 14 weeks of age had inadequate antibody titers at 17 weeks of age. Kittens may be vaccinated in the perioperative period when necessary, and the primary vaccination series should be extended through at least 16 weeks of age.     

Efficient selection of potato heterokaryons by flow cytometric sorting and the regeneration of hybrid plants

Drought is one of the important factors limiting crop production in arid and semi-arid regions. Four drought resistance criteria, consisting of canopy temperature, stomatal resistance, transpiring area and rate of water loss by excised-leaves were examined in two experiments conducted in optimum and stress moisture conditions in 1995. A randomized complete block design with four replications and six genotypes was used for each experiment. Under optimum moisture conditions, there was a significant difference in canopy temperature at midday between drought resistant and drought sensitive genotypes. A significant linear relationship was also obtained between this criterion and yield reduction ratio as determined by Y_r = 1-(Y_s/Y_p) (Y_s and Y_p = yield under stress and non-stress conditions, respectively), at the ear emergence stage. The only significant difference between cultivars in respect to stomatal resistance in stress conditions was that of adaxial leaf surface in ear emergence stage. No significant linear relationship was obtained between transpiring area and yield reduction ratio. Cultivars differed in respect to rate of water loss (RWL) and initial water content (IWC) in ear emergence and grain filling in stress environment only. Ultimately, three criteria namely canopy temperature, stomatal resistance and RWL, in explicated conditions were recognized as benificial drought resistance indicators. This revised version was published online in July 2006 with corrections to the Cover Date.