An overall view of temperature oscillations in the solar chromosphere with ALMA.

By direct measurements of the gas temperature, the Atacama Large Millimeter/submillimeter Array (ALMA) has yielded a new diagnostic tool to study the solar chromosphere. Here, we present an overview of the brightness-temperature fluctuations from several high-quality and high-temporal-resolution (i.e. 1 and 2 s cadence) time series of images obtained during the first 2 years of solar observations with ALMA, in Band 3 and Band 6, centred at around 3 mm (100 GHz) and 1.25 mm (239 GHz), respectively. The various datasets represent solar regions with different levels of magnetic flux. We perform fast Fourier and Lomb-Scargle transforms to measure both the spatial structuring of dominant frequencies and the average global frequency distributions of the oscillations (i.e. averaged over the entire field of view). We find that the observed frequencies significantly vary from one dataset to another, which is discussed in terms of the solar regions captured by the observations (i.e. linked to their underlying magnetic topology). While the presence of enhanced power within the frequency range 3-5 mHz is found for the most magnetically quiescent datasets, lower frequencies dominate when there is significant influence from strong underlying magnetic field concentrations (present inside and/or in the immediate vicinity of the observed field of view). We discuss here a number of reasons which could possibly contribute to the power suppression at around 5.5 mHz in the ALMA observations. However, it remains unclear how other chromospheric diagnostics (with an exception of Hα line-core intensity) are unaffected by similar effects, i.e. they show very pronounced 3-min oscillations dominating the dynamics of the chromosphere, whereas only a very small fraction of all the pixels in the 10 ALMA datasets analysed here show peak power near 5.5 mHz. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.

Transverse motions in sunspot super-penumbral fibrils.

Sunspots have played a key role in aiding our understanding of magnetohydrodynamic (MHD) wave phenomena in the Sun's atmosphere, and it is well known they demonstrate a number of wave phenomena associated with slow MHD modes. Recent studies have shown that transverse wave modes are present throughout the majority of the chromosphere. Using high-resolution Ca II 8542 Å observations from the Swedish Solar Telescope, we provide the first demonstration that the chromospheric super-penumbral fibrils, which span out from the sunspot, also show ubiquitous transverse motions. We interpret these motions as transverse waves, in particular the MHD kink mode. We compile the statistical properties of over 2000 transverse motions to find distributions for periods and amplitudes, finding they are broadly consistent with previous observations of chromospheric transverse waves in quiet Sun fibrils. The very presence of the waves in super-penumbral fibrils raises important questions about how they are generated, and could have implications for our understanding of how MHD wave energy is transferred through the atmosphere of a sunspot. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.

Investigating Alfvénic wave propagation in coronal open-field regions.

The physical mechanisms behind accelerating solar and stellar winds are a long-standing astrophysical mystery, although recent breakthroughs have come from models invoking the turbulent dissipation of Alfvén waves. The existence of Alfvén waves far from the Sun has been known since the 1970s, and recently the presence of ubiquitous Alfvénic waves throughout the solar atmosphere has been confirmed. However, the presence of atmospheric Alfvénic waves does not, alone, provide sufficient support for wave-based models; the existence of counter-propagating Alfvénic waves is crucial for the development of turbulence. Here, we demonstrate that counter-propagating Alfvénic waves exist in open coronal magnetic fields and reveal key observational insights into the details of their generation, reflection in the upper atmosphere and outward propagation into the solar wind. The results enhance our knowledge of Alfvénic wave propagation in the solar atmosphere, providing support and constraints for some of the recent Alfvén wave turbulence models.

Bacterial cell microarrays for the detection and characterization of antibodies against surface antigens.

Bacterial cell surface antigens interact with the host immune system resulting in the production of antibodies. Detection of antibodies against surface antigens has applications in diagnosis of many bacterial infections, assessment of immune status and epidemiological studies. We developed a microarray platform, for antibody detection, by printing Gram-negative and Gram-positive whole bacterial cells on nitrocellulose coated glass substrates. Antibody binding was detected using fluorophore labeled secondary antibodies. The sensitivity of antibody detection was found to be 0.1 microg/ml. Using bacterial cell microarrays it was also possible to successfully detect antibodies against Francisella tularensis in canine serum samples declared positive for tularemia based on microagglutination antibody titer. Use of bacterial cells as the antigen source in immunoassays has the advantages of simulating in vivo presentation of surface antigens and also eliminating the need for antigen purification. The microarray format gives the added advantage of simultaneous detection of antibodies against multiple bacteria employing only small amounts of samples and reagents.

Lipopolysaccharide microarrays for the detection of antibodies.

Lipopolysaccharide (LPS) is the major component of Gram-negative bacterial outer membrane. LPS are immunogenic and show species/strain specificity. The demonstration of anti-LPS antibodies in clinical samples is of diagnostic value in certain Gram-negative bacterial infections. In the present study we explored the possibility of immobilizing LPS isolated from different bacteria in a microarray format for the detection of anti-LPS antibodies. LPS was successfully immobilized on nitrocellulose-coated glass slides, preserving the accessibility of epitopes for antibody binding. Specificity of the LPS arrays was established using four different monoclonal antibodies specific for Escherichia coli O111, E. coli O157, Francisella tularensis and Salmonella typhimurium O-antigens and a panel of LPS preparations. The detection limit of antibodies was found to be 10 ng/ml, which is about a 100-fold greater sensitivity compared to conventional immunofluorescence assays. Furthermore, using LPS arrays, tularemia positive canine serum samples could be differentiated from negative samples based on the presence of significantly higher levels of anti-F. tularensis LPS antibodies in positive samples. LPS arrays will facilitate simultaneous screening of samples against multiple antigens and are expected to find applications in diagnostics and seroepidemiology.

Development of an ex vivo model to study adherence of Mannheimia haemolytica serovar 1 to mucosal tissues of the respiratory tract of cattle.

OBJECTIVE: To develop and validate an ex vivo model for study of adherence of Mannheimia haemolytica (formerly Pasteurella haemolytica) to respiratory tract mucosa of cattle and to use this model to confirm adherence of M haemolytica serovar 1 (Mh1) to several relevant respiratory mucosal surfaces. SAMPLE POPULATION: Excised nasal, nasopharyngeal, turbinate, and tonsillar mucosal tissue from the bovine upper respiratory tract. PROCEDURE: Mh1 was radiolabeled by use of tritiated leucine. Various concentrations of labeled bacteria were incubated with bovine upper respiratory tract tissues for various times. Tissue was washed to remove nonadherent bacteria, and percentage of bacteria adhered (percentage of adherence) was estimated using radioactivity. Using an optimal inoculum concentration and incubation time, percentage of Mh1 adherence was compared on nasal, nasopharyngeal, turbinate, and tonsillar mucosal tissue, and adherence to nasopharyngeal tissue was confirmed by scanning and transmission electron microscopy. RESULTS: The optimal Mh1 inoculum concentration was 1 X 10(7) colony forming units/ml and incubation time was 3 hours. Percentage of adherence of Mh1 to nasopharyngeal tissue was greater than adherence to other tissue types. CONCLUSIONS AND CLINICAL RELEVANCE: The ex vivo model maintained the functional and structural integrity of bovine upper respiratory tract mucosa, as confirmed by light and electron microscopy. Electron microscopy revealed participation of epithelial cell cilia and surface mucus in adherence of Mh1 to nasopharyngeal tissue. Adherence of Mh1 was confirmed in repeated assays, indicating that this organism adheres to upper respiratory tract mucosa of cattle.

Development of an in vitro fluorometric assay to study adherence of Pasteurella haemolytica to bovine cells.

OBJECTIVE: To develop an in vitro fluorometric assay to assess Pasteurella haemolytica adherence to bovine respiratory and epithelial cells and compare adherence of single strains of P. haemolytica serovars A1 and A2 (PhA1 and PhA2, respectively). SAMPLE POPULATION: Monolayers of bovine turbinate and Madin Darby bovine kidney (MDBK) cells. PROCEDURE: To determine optimal inoculum concentration and incubation time, various concentrations of P. haemolytica were labeled with fluorescein isothiocyanate and incubated with monolayers of bovine cells for various times. Bovine cells were washed to remove nonadherent bacteria, and percentage of bacteria adhered (percentage of adherence) was estimated fluorometrically. Percentage of adherence of PhA1 was compared with that of PhA2. RESULTS: The optimal inoculum concentration that resulted in measurable fluorescence of adherent bacteria was 1 x 10(8) colony-forming units/ml, and the optimal incubation time was 45 minutes. Percentage of adherence of PhA1 to MDBK and turbinate cells was significantly greater than that determined for PhA2. CONCLUSIONS: The in vitro fluorometric assay is a time-efficient, inexpensive, and labor-saving method for evaluation of P. haemolytica adherence to bovine cells. The concentration of bacteria used to inoculate bovine cells in this assay is similar to that typically used in other types of in vitro adherence assays. The predominance of PhA1 over PhA2 during the early stages of bovine respiratory disease may be attributable to the ability of PhA1 to adhere more avidly to nasopharyngeal tissue.

Tularemia in two cats.

Tularemia was diagnosed in 2 cats that were examined because of pyrexia and lethargy; both cats had a history of exposure to wild rabbits. One cat was vomiting, and the other was anorectic. Physical examination revealed dehydration, lymphadenopathy, and hepatomegaly. Hematologic and serum biochemical abnormalities included toxic neutrophils, high band neutrophil count, thrombocytopenia, and hyperbilirubinemia. Diagnosis was confirmed by isolating Francisella tularensis subsp tularensis from bone marrow or lymph node aspirates. Evaluation of samples collected during the acute and convalescent phases of the disease revealed an increase in serum F tularensis antibody titer. Both cats responded to treatment with fluids and antibiotics.

Major outer membrane proteins of Pasteurella haemolytica serovars 1-15: comparison of separation techniques and surface-exposed proteins on selected serovars.

The Sarkosyl method of obtaining outer membrane proteins (OMPs) from Pasteurella haemolytica A1 was more efficient and less laborious than separating membranes by sucrose gradient centrifugation. More OMPs were recovered and major OMPs were present in greater concentrations in the Sarkosyl-derived preparations. Therefore, OMPs of P. haemolytica serovars 1-15 (serovars 3, 4, 10, and 15 being T biotypes and the remainder being A biotypes) were prepared by the Sarkosyl method and compared by SDS-PAGE. Serovars 1, 2, 5, 6, 7, 8, 11, and 12 which are A biovars had similar OMP profiles characterized by major OMPs of 30.5 and 43 kDa. Biovar T strains were characterized by doublet protein bands in the 26-28 kDa region and a major OMP in the 38-40 kDa range. Serovars 9, 13, and 14, which are also A biovars, had profiles similar, although not identical, to the T biovars. A 43 kDa protein was present in all serovars although concentration was greater in the A biovars. Surface-exposed proteins of P. haemolytica A1 determined by 125I-labeling of whole cells were 94, 84, 53.5, 49, 43, 41, 29.5, and 16 kDa. Iodine-labeling of serovars A2 and A6 which have similar OMP profiles by SDS-PAGE resulted in autoradiographs indistinguishable from A1. These studies expand our knowledge of P. haemolytica OMPs especially showing the utility of the Sarkosyl extraction procedure, variations in OMP profiles among some A biovar strains, and the similarities of OMP profiles and surface-labeled proteins among three of the most important serovars (1, 2, and 6).

A pathogenic challenge model for adult northern bobwhite (Colinus virginianus) using a vaccine strain of Pasteurella multocida type 3.

A pathogenic challenge model causing approximately 50% mortality was developed in adult Northern bobwhite (Colinus virginianus) using Avichol, a live vaccine containing the Clemson University (CU) strain of Pasteurella multocida Type 3. A dose of 2300 or 3000 colony-forming units (CFU) of Avichol injected intramuscularly resulted in 30 to 75% mortality, whereas a dose of 230 CFU or less resulted in no mortality, and 58,720 CFU or more resulted in death in all birds challenged. Primary and secondary vaccination of Northern bobwhite with a formalinized anaculture of Avichol -derived P. multocida resulted in protection against challenge in three separate experiments. Dexamethasone treatment of birds during vaccination resulted in decreased protection against challenge exposure.

Serum antibody responses of cattle to iron-regulated outer membrane proteins of Pasteurella haemolytica A1.

Serum antibody responses to the 70, 77, and 100 kDa iron-regulated outer membrane proteins (IROMPs) of Pasteurella haemolytica A1 were studied in cattle vaccinated with outer membrane protein (OMP) enriched outer membrane fraction, IROMP-enriched outer membrane fraction or live P. haemolytica. Vaccination with an IROMP-enriched outer membrane fraction stimulated antibodies to the 70 kDa IROMP, whereas vaccination with live P. haemolytica stimulated antibodies to the 70 and 77 kDa IROMPs. In a second experiment, sera were used from cattle vaccinated with live or killed P. haemolytica and subsequently challenged. Significant antibody responses to OMP- and IROMP-enriched outer membrane fractions were detected by an enzyme-linked immunosorbent assay (ELISA) for cattle vaccinated with bacterins or live P. haemolytica. Regression analysis indicated significant correlations between high antibody responses to the OMP- or IROMP-enriched fraction and resistance to challenge. Antibody responses to the 70 and 77 kDa IROMPs were significantly greater for the live P. haemolytica vaccinates than for PBS control vaccinates. There was no significant correlation between antibody responses to individual IROMPs and resistance or susceptibility to challenge. These data suggest that antibodies to IROMPs alone are probably not responsible for protective immunity against pneumonic pasteurellosis. Antibodies to IROMPs, however, in conjunction with antibodies to other surface antigens probably enhance immunity to P. haemolytica challenge.

Vaccination of cattle with outer membrane protein-enriched fractions of Pasteurella haemolytica and resistance against experimental challenge exposure.

Administration of an N-lauroylsarcosine-derived outer membrane protein fraction of Pasteurella haemolytica A1 (SCI-1) induced a protective response in calves against intrathoracic challenge exposure with the homologous serovar. Outer membrane proteins from heterologous serovars, A6 and A9, induced partial protection that was associated with their respective similarities to serovar A1 in outer membrane protein profiles derived by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Calves vaccinated with SCI preparations did not have detectable neutralizing antibody to P haemolytica A1 leukotoxin. Antibodies to whole-cell antigens, carbohydrate-protein subunit antigen, and SCI-1 were associated with resistance, which indicates that protein antigens shared among cell surface, carbohydrate-protein subunit, and SCI preparations are immunogenic and enhance resistance to experimental challenge exposure.

Action of quail and chicken interferons on a quail cell line, QT35.

Production of interferon (IFN) in quail cells (QT35) and the activity of quail IFN and heterologous avian IFN (chicken) on QT35 cells were examined. Quail cells produced IFN after induction by bluetongue virus serotype 10; chicken and quail IFN conferred antiviral resistance on the quail cells. Both chicken and quail IFN induced increased levels of 2',5'-oligoadenylate synthetase (2',5'-OAS) in QT35 cells and reduced levels of intracellular Salmonella typhimurium postchallenge. These results indicate that the quail cells produce IFN and respond to homologous and heterologous avian IFN as evidenced by enhanced (1) resistance to viral infection, (2) production of 2',5'-OAS, and (3) resistance to invasion by bacteria. QT35 quail cell monolayer cultures offer an alternative to primary chicken embryo fibroblasts cultures used for avian IFN studies.

Pasteurella haemolytica leukotoxin-induced synthesis of eicosanoids by bovine neutrophils in vitro.

Exposure of isolated bovine neutrophils to partially purified Pasteurella haemolytica leukotoxin caused increased synthesis of leukotriene B4 (LTB4) but not thromboxane B2 (TXB2) from endogenous arachidonic acid. Synthesis of LTB4 was closely correlated with leukotoxin-induced neutrophil lysis. At low toxin concentrations, LTB4 production lagged behind leukotoxin-induced neutrophil lysis over a 3-h period. The neutralizing monoclonal antileukotoxin antibody MM601 neutralized both leukotoxin-induced neutrophil lysis and LTB4 synthesis. Both leukotoxin-induced neutrophil lysis and LTB4 synthesis were Ca(2+)-dependent. When leukotoxin-induced LTB4 synthesis from exogenous arachidonic acid was examined, significant LTB4 synthesis occurred at 5 min of leukotoxin exposure, which was before leukotoxin-induced lysis developed. Leukotoxin-induced LTB4 synthesis from endogenous arachidonic acid appears to require leukotoxin-induced plasma membrane damage (occurring during neutrophil lysis), whereas LTB4 synthesis from exogenous arachidonic acid is initiated rapidly and occurs in the absence of plasma membrane damage.

Experimental Brucella abortus strain 19 arthritis in young cattle.

Several reports have shown an association between lameness in cattle and vaccination with Brucella abortus strain 19. Affected joints are culture negative for Brucella, but the synovial fluid is positive for B. abortus antibodies. The joints contain cloudy fluid, with villous proliferation of the synovium. Brucella abortus antigens are often found in the synovium with fluorescent antibody staining. This report describes the experimental reproduction of a chronic synovitis in 6 young Angus steers using intra-articular injections of B. abortus strain 19. The carpal and tibial joints were injected with 5 x 10(9) colony-forming units/ml of B. abortus strain 19 and regularly biopsied over a 28-day period. Steers started becoming serologically positive for B. abortus on post-inoculation day (PID) 5 and were all positive by PID 7. Joints were cultured and examined by fluorescent antibody staining, immunohistochemical methods, and light and transmission electron microscopy. Lesions typical of the field cases were present by PID 21. Brucella abortus was cultured more often during PID 1-5 (6 of 9 joints) than during PID 7-28 (3 of 15 joints). Brucella abortus was only found on PID 1 and 5 by fluorescent antibody staining and in only 2 joints immunohistochemically on PID 5 and 7. The reproduction of lesions typical of field cases but the inability to locate B. abortus antigens in the synovium raises the question of whether in field cases the synovium is continually or intermittently seeded with bacteria or if factors other than just the bacterium are needed to perpetuate the lesion.