Fungi as potential factors limiting natural regeneration of pedunculate oak (Quercus robur) in mixed-species forest stands in Poland

Dieback of young Quercus robur seedlings can limit natural regeneration in mixed-species forest stands in Poland. The aim of this study was to examine the role of fungi in the dieback of oak seedlings in central Europe. Fungi were isolated from the stems and roots of Q. robur, from both healthy seedlings and seedlings with symptoms, that were sampled from four stands in Poland. In total, 111 distinct taxa were identified. Ascomycota was dominant, representing 95.6% of the isolates. Among the taxa identified, Alternaria alternata, Colletotrichum fioriniae, Colletotrichum godetiae, Coniella quercicola, Diaporthe eres, Gnomoniopsis paraclavulata, Ilyonectria rufa, Mucor genevensis, Penicillium glandicola, Tubakia dryina, and Umbelopsis changbaiensis were most frequently isolated, and were consistently found in stems and roots of both healthy and diseased plants. The community compositions of fungi in healthy and diseased stems were similar, although Fusarium species, especially Fusarium sp. 1 (FTSC 5) and F. sporotrichioides, were found mainly in seedlings with symptoms. The pathogenicity of the most consistently isolated species from stems and roots of diseased seedlings was tested on Q. robur seedlings. F. sporotrichioides caused the largest lesions on inoculated seedlings. Six weeks after inoculation, D. eres, C. fioriniae, G. paraclavulata, T. dryina, and F. sporotrichioides killed 0%–18.8% of seedlings, while I. rufa and Ilyonectria pseudodestructans did not cause any lesions or other symptoms. This study is the first comprehensive report suggesting that massive fungal attack can lead to oak seedling dieback in mixed-species forest stands in central Europe.     

Role of Blowing Agents in Expansion of High‐Amylose Starch Acetate During Extrusion

High‐amylose starch acetate (DS 2) was processed in a Brabender twin‐screw extruder with ethanol and isopropanol as blowing agents at concentrations of 0, 2, 5, 10, 15, and 25%. A constant temperature of 150°C, a constant screw speed of 140 rpm, and a die nozzle with diameter of 4.0 mm and length of 16.2 mm were used to study the role of blowing agents on the expansion of the extrudates. Extrudates without blowing agent shrunk considerably after exiting the die as the cells collapsed drastically after expansion. Stable radial expansion of the extrudates increased with increase in the ethanol concentration to an optimum value of 18.0 at 5% (db) ethanol concentration and decreased with further increase in the ethanol concentration. Stable radial expansion increased to a maximum of 17.0 as the concentration of isopropanol was increased to 25% (db), though the rate of increase in expansion decreased with the increase in isopropanol concentration >10%. Flashing off of blowing agents aided in removing the heat generated during extrusion. The faster the extrudate cooled, the less likely it was to shrink. SEM were used to observe the effects of concentration of blowing agents on cell morphology. Various phenomena involved during the expansion are discussed. To obtain an extrudate with high expansion and low density, isopropanol at 15–25% (db) was found most suitable in this study.     

Starch Acetate‐Maleate Mixed Ester Synthesis and Characterization

A new starch acetate‐maleate mixed ester with different degrees of substitution (DS) for each ester group was prepared. High‐amylose (70%) corn starch was first reacted at 123°C with ≈4.5 equivalents of acetic anhydride for different times, and then the intermediate products were further reacted at 80°C with 0.27–1.1 equivalents of maleic anhydride for a fixed time. ¹H NMR and alkaline saponification were used to determine DS values of acetyl and maleate groups. Increasing the reaction time from 60 to 120 min for starch and acetic anhydride increased DS of the acetyl group, while DS of the maleate group increased with increasing amounts of maleic anhydride. There was a good agreement between the two methods for DS determination. The reaction efficiency of acetylation increased from ≈30 to 50% with reaction time, and maleation decreased from ≈30 to 20% with increasing amounts of maleic anhydride. The mixed esters were characterized by ¹H NMR, ¹³C NMR, FTIR, DSC, and TGA. Characteristic peaks in ¹H NMR, ¹³C NMR, and FTIR spectra indicated the presence of acetyl and maleate groups in starch molecules. The exothermic peak in the DSC curve and the increase in thermal stability from the TGA curve were attributed to thermal cross‐linking of the double bond of the maleate group.     

Sialodacryoadenitis in the rat: effects of immunosuppression on the course of the disease

Eight-week-old outbred male and female Crl:CD(SD)BR rats were treated with prednisolone (PR) or cyclophosphamide (CY) and were inoculated intranasally with sialodacryoadenitis (SDA) virus. The course of the disease was compared with nonimmunosuppressed, SDA virus-inoculated rats of the same stock. Criteria used to compare SDA in the 3 groups, included histologic changes in salivary and lacrimal glands, immunofluorescent microscopy of paraffin-embedded tissues, serum amylase levels, and antibody response. Based on these criteria, there was little detectable difference in the course and intensity of SDA in PR-treated and nonimmunosuppressed rats. In CY-treated rats, there was a delay in the onset of SDA, in the appearance of inflammatory cells in affected glands, and in the reparative process in the salivary and lacrimal glands. Viral antigen persisted longer in CY-treated rats than in PR-treated and nonimmunosuppressed rats. Antibody to SDA virus was not detected in CY-treated rats. The efficacy of immunosuppression by PR and CY was confirmed by the sheep erythrocyte agglutination procedure performed in selected rats. Male and female rats of the same strain were immunosuppressed beginning 4 weeks after inoculation with SDA virus to produce recrudescence of the disease. Histologic examination of salivary and lacrimal glands, immunofluorescent microscopy, serum amylase values, and viral isolation studies did not reveal evidence of reactivation of a persistent viral infection or viral shedding. Based on these studies, there is no evidence that SDA virus may persist as an inapparent infection after recovery from the disease.     

Equine immunology 4: vaccines and antisera

This paper attempts to relate the practicalities of vaccine development to the ideals which should be aimed for in a new vaccine. The type of immune response induced is dependent upon the nature of the antigen in the vaccine and the site and timing of its presentation to the immune system. In this respect the influence of age, maternal immunity and antigenic competition are discussed. The possible side effects associated with vaccination are defined and vaccines which are currently available for horses are reviewed. These vaccines are mostly for the prevention of respiratory disease. Finally, the possible uses for antisera are considered.     

Enzyme linked immunosorbent assay for detection of antibodies againstBesnoitia besnoiti in cattle

The use of the ELISA method for the detection of antibodies to B. besnoiti in cattle is described and compared to the IFAT technique. One hundred and twenty-one sera were examined, of which 61 were sera of calves experimentally infected with B. besnoiti, 52 sera from field animals and eight were sera with high titres of antibodies to other parasites. The specificity of both assays correlates but ELISA seemed to be more sensitive. The ELISA technique provides a rapid and reliable method for the screening of B. besnoiti infection in cattle.     

Specific antibodies to Besnoitia besnoiti precipitated from serum of cattle by live parasites and by soluble antigen

Specific precipitable antibodies of both IgG and IgM classes were detected in sera of cattle naturally infected with B. besnoiti. The amount of specific antibodies of the IgG class precipitated by soluble antigen was in the range of 17-50 micrograms/ml serum while that of the IgM class ranged between 5 and 24 micrograms/ml serum. Specific antibodies precipitated by live B. besnoiti parasites were in amounts of 10 to 22 micrograms/ml serum for IgG and 4 to 26 micrograms/ml serum for IgM. Different ratios of IgG/IgM were obtained by the two methods of precipitation. This might indicate that antibodies to B. besnoiti of the IgM class can be precipitated and detected in sera of naturally infected cattle in similar amounts either by live parasites or by solubilized antigen, whereas antibodies of the IgG class can be preferentially detected when solubilized antigen is used for precipitation.     

Excretion of Mycobacterium bovis by experimentally infected cattle

Three groups, each of five calves, four to seven months old, were inoculated intranasally with different numbers of Mycobacterium bovis. Infection was established readily in the calves which received an inoculum containing either 10(6) or 10(4) colony forming units (cfu). After every infection there was a lag period during which the organisms could not be isolated from specimens of nasal mucus. All the animals excreted M bovis and the time of commencement, quantity and duration of excretion appeared to be related to the inoculation dose. Excretion continued for many weeks, and for two calves excretion became intermittent over many months. All the calves which were given inocula of 92 cfu failed to develop the disease and no immunological responses were detected; however, M bovis was isolated from nasal secretions from one of these animals 100 days after inoculation.     

Circulating immune complexes in bovine leukemia virus (BLV)-infected cattle.

Circulating immune complexes (ICs) were detected in the sera of bovine leukemia virus (BLV)-seropositive cattle. Immune complexes were precipitated in 2.5% polyethylene glycol (PEG) and further dissociated. Bovine leukemia virus antigens, IgG and IgM molecules were detected after solubilization in the presence of sodium dodecyl sulphate, and quantitated by enzyme-linked immunosorbent assay (ELISA) assays. Mean values of IgG and IgM in BLV-containing ICs did not significantly differ from those obtained from ICs originating from BLV-seronegative animals. However, differences were found in the composition of ICs from older BLV-positive animals as compared to those obtained from young animals. The ratio of IgG/IgM was 5.02 in animals aged 5-10 years, while this ratio was 11.66 in animals of less than 5 years of age and 10.19 in controls. This might indicate a possible increase in the contribution of IgM molecules to the structural composition of ICs in BLV-infected cattle as related to age or stage of infection.     

Immunogenicity and allergenicity of Culicoides imicola (Diptera: Ceratopogonidae) extracts

Summer seasonal recurrent dermatitis (SSRD) or "sweet itch" is a seasonally occurring allergic dermatitis of horses provoked by biting midges. The allergic skin reactions have been attributed to allergens present in various Culicoides species. C. imicola is the suspected etiological agent of SSRD in Israel. Whole body extracts of this midge induced hypersensitivity reactions upon injection into susceptible horses and in this study attempts were made to define components of C. imicola which have immunogenic and allergenic properties. Immunogenic potency was evaluated by raising antisera to whole body extracts of C. imicola in rabbits and examining their reactivity towards fractionated extracts. Allergenic potency was examined by reacting fractionated extracts with horse sera. Humoral reactivity of susceptible and non susceptible horses was assayed by specific IgE and IgG ELISAs. Although there are many antigenic components in whole body extracts of C.imicola capable of eliciting an immune response, no conclusive evidence was obtained indicating that allergic reactivity was associated with increased IgE levels of defined specificity.