使用灭活疫苗低致病性禽流感

在一个国家或地区广泛使用优质的H9N2灭活疫苗,可明显减少该地区禽流感的暴发次数,降低由禽流感给养禽业带来的经济损失。     

Reference blood chemical values in ostriches (Struthio camelus)

Reference blood chemical values were determined for 65 male and 61 female ostriches (Struthio camelus) 1 month to 72 months of age. Plasma values of glucose, total protein, triglycerides, cholesterol, uric acid, urea, bilirubin, creatinine, osmolality, electrolytes, and enzyme activity were determined. In general, differences in various values appeared mainly among age groups and less so between sexes. Older ostriches had lower plasma glucose values and enzyme activity than did younger ostriches. High plasma sodium and chloride concentrations in young ostriches correlated with high plasma osmolalities. Plasma calcium values were lower in laying ostriches. Uric acid concentrations were markedly higher than were urea concentrations in all ostriches.     

Chicken infectious anemia virus infection in Israeli commercial flocks: virus amplification, clinical signs, performance, and antibody status

The impact of chicken infectious anemia virus (CIAV) infection on commercial chicken flocks in Israel was examined by analyzing flocks with or without typical CIAV signs, signs of other diseases, or apparently healthy flocks. In 23 flocks (broilers and layers) of ages up to 8 wk, typical signs of CIAV infection (stunting, gangrenous dermatitis, and secondary bacterial infections) were recorded. When permitted by flock owners, in several cases among these 23 flocks the morbidity, mortality, and performance parameters were recorded; the presence of CIAV was detected by polymerase chain reaction (PCR); and the antibody status of parents and broilers was measured. In addition, total mortality, number of birds sold, total kilograms of meat sold, density (kg/m2), mean age at slaughter, daily growth rate in grams, total kilogram of food consumed, food conversion rate, and the European Index were calculated. We also surveyed flocks affected by other diseases, such as tumors, respiratory diseases, or coccidiosis, and flocks with no apparent clinical signs. The latter flocks were negative by CIAV-PCR, indicating that typical CIAV clinical signs are associated with one-step PCR-CIAV amplification. However, a small amount of CIAV might still be present in these flocks, acting to induce the subclinical effects of CIAV infection. These data indicate a link between the presence of virus sequences and typical CIAV signs and strengthen the concept that CIAV infection has a negative economic impact on the chicken industry.     

Interaction with salinity of GA3-induced leaf elongation,petiole pithiness and bolting in celery

GA₃ sprayed on celery plants, which received a continuous supply of 0, 0.2, 0.4, 0.6 or 1.0% NaCl solutions to the roots, caused a pronounced increase in leaf elongation.Along with enhanced elongation, GA₃ increased breakdown of parenchymatous tissue in the petiole, but this effect was drastically suppressed in the salt-treated plants. In a similar fashion, the effect of GA₃ on the elongation of the flowering-stem (bolting) was significantly diminished in salt-treated plants. In no case did the salinity treatment totally abolish the bolting-process induced by GA₃.Changing the temperature of the lower part of the root system altered the magnitude of GA₃ effect on bolting. As the temperature was lowered from 30 to 6° C, the ability of GA₃ to cause bolting was greatly reduced.The results are discussed in view of the possible interaction between salinity and the GA₃ effect on petiole elongation, cellular breakdown and bolting.     

The effect of infectious bursal disease virus on the immune system of turkeys

In 1979 it was reported that an infectious bursal disease virus (IBDV) isolated from a case of respiratory disease of turkeys differed antigenically from the chicken isolates of this virus. We injected turkey poults with the turkey-originating TY89 and chicken-originating BD/6 isolates of IBDV and studied their effects on antibody production to the virus, serum immunoglobulin G (IgG), antibody response to sheep erythrocytes, in vitro response of peripheral blood lymphocytes to mitogens, and microscopic structure of the bursa of Fabricius. The chicken isolate BD/6 caused a significant decrease in the response to sheep erythrocytes, lower serum IgG, transient decrease in the response of lymphocytes to PHA, and mild microscopic lesions in the bursa of Fabricius. The turkey isolate TY89, however, caused no obvious damage to the immune system of the infected poults. We suggest that a partial and transient functional disorder of the immune system of poults can occur after infection with IBDV originating from chickens, even if the poults exhibited no clinical signs.     

<Emphasis Type="Italic">Botrytis cinerea</Emphasis> induces senescence and is inhibited by autoregulated expression of the <Emphasis Type="Italic">IPT</Emphasis> gene

Botrytis cinerea is a non-specific, necrotrophic pathogen that attacks many plant species, including Arabidopsis and tomato. Since senescing leaves are particularly susceptible to infection by B. cinerea, we hypothesized that the fungus might induce senescence as part of its mode of action and that delaying leaf senescence might reduce the severity of B. cinerea infections. To examine these hypotheses, we followed the expression of Arabidopsis SAG12, a senescence-specific gene, upon infection with B. cinerea. Expression of SAG12 is induced by B. cinerea infection, indicating that B. cinerea induces senescence. The promoter of SAG12, as well as that of a second Arabidopsis senescence-associated gene, SAG13, whose expression is not specific to senescence, were previously analyzed in tomato plants and were found to be expressed in a similar manner in the two species. These promoters were previously used in tomato plants to drive the expression of isopentenyl transferase (IPT) from Agrobacterium to suppress leaf senescence (Swartzberg et al. in Plant Biology 8:579–586, 2006). In this study, we examined the expression of these promoters following infection of tomato plants with B. cinerea. Both promoters exhibit high expression levels upon B. cinerea infection of non-senescing leaves of tomato plants, supporting our conclusion that B. cinerea induces senescence as part of its mode of action. In contrast to B. cinerea, Trichoderma harzianum T39, a saprophytic fungus that is used as a biocontrol agent against B. cinerea, induces expression of SAG13 only. Expression of IPT, under the control of the SAG12 and SAG13 promoters in response to infection with B. cinerea resulted in suppression of B. cinerea-induced disease symptoms, substantiating our prediction that delaying leaf senescence might reduce susceptibility to B. cinerea. Contribution from the Agriculture Research Organization, The Volcani Center, Bet Dagan, Israel, No. 127/2006 series.