Tumor necrosis factor alpha and its receptors in experimentally bovine leukemia virus-infected sheep

To examine whether tumor necrosis factor alpha (TNF alpha) contributes to the pathogenesis of bovine leukemia virus (BLV) infection, the mRNA expression patterns of TNF alpha and its receptors, type 1 (TNF R1) and type 2 (TNF R2) were investigated. Sheep inoculated with BLV were divided into two groups; one was BLV-positive and the other BLV-negative based on the detection in peripheral blood mononuclear cells (PBMC). Expression of TNF R1 mRNA was down-regulated in PBMC from the BLV-positive compared to BLV-negative sheep. No difference was shown in the expression levels of TNF R2 mRNA between the two groups. Furthermore, proliferative responses of PBMC in the presence of TNF alpha were observed from the BLV-positive, but not BLV-negative sheep. Membrane-bound TNF alpha (mTNF alpha) is thought to be one of the ligands, inducing B-cell activation. Flow cytometric analysis demonstrated that the number of PBMC, that were positive for mTNF alpha expression, was increased in the BLV-positive sheep. Thus, the expression of TNF alpha and its receptors may be closely associated with lymphocytosis induced by BLV.     

Host immune responses in the course of bovine leukemia virus infection

Bovine leukemia virus (BLV) is a type C retrovirus infecting bovine B cells and causing enzootic bovine leukosis. Since it takes long periods to develop the disease, it is believed that BLV and host immune responses are closely related. In this review, the accumulated data showing close relationship between BLV and host immune responses are summarized in 4 sections. First, we discuss the role of cell-mediated immunity in protecting hosts from BLV infection. Second, several reports showing the relationship between the disease progression and the change of cytokine profiles are summarized. In the third section, we have focused on tumor necrosis factor alpha (TNFalpha) and its two types of receptors, and the possible involvement of TNFalpha in the BLV-induced leukemogenesis is discussed. The expression of TNFalpha has been shown to be regulated by major histocompatibility complex (MHC) haplotype. The resistance to BLV infection is supposed to be established by some innate factors, which are closely related to MHC haplotype. Finally, we propose that a breeding strategy based on the MHC haplotype could be a good approach to control BLV infection. This review includes some recent data from us and other groups.     

Cytokine responses in camels (Camelus bactrianus) vaccinated with Brucella abortus strain 19 vaccine

In the present study, we determined the levels of cytokines produced by camel (Camelus bactrianus) peripheral blood mononuclear cells (PBMCs) in response to live attenuated Brucella abortus (B. abortus) S19 vaccine. Seven camels were vaccinated with commercial B. abortus S19 vaccine, and their cytokine responses were determined using a real-time PCR assay. Cytokine responses to B. abortus S19 were examined at 6 hr, 48 hr and 1, 2 and 3 weeks post-vaccination. Serological tests were performed to further confirm these immune responses. The results revealed that IFN-gamma and IL-6 were upregulated during the first week post-vaccination. Low level expressions of IL-1alpha, IL-1beta, TNFalpha and IL-10 and no expression of IL-2 and IL-4 were observed compared with the control camels. The findings showed that B. abortus stimulates cell-mediated immunity by directly activating camel Th1 cells to secrete IFN-gamma. This quantification of cytokine expression in camels is essential for understanding of Camelidae disease development and protective immune responses. This is the first report of in vivo camel cytokine quantification after vaccination.     

Role of beta1 integrins in adhesion of canine mastocytoma cells to extracellular matrix proteins

The interactions of tumor cells with the extracellular matrix (ECM) are a crucial step in invasion and metastasis. Integrins are adhesive molecules forming heterodimers with alpha and beta subunits that play a definitive role in these interactions. In this study, mastocytoma (mast cell tumor: MCT) cell-ECM interaction was investigated using 3 canine MCT cell lines: CM-MC (originating from cutaneous MCT), VI-MC (originating from intestinal MCT), and CoMS (originating from oral MCT). Flow cytometric analysis showed that all cells highly expressed the integrin beta1 and alpha1 through alpha5 subunits and that they moderately expressed the alpha6 subunit. In adhesion studies, CoMS weakly but spontaneously adhered to fibronectin (FN), which was enhanced by phorbol ester (TPA), while CM-MC and VI-MC required cell activation by TPA to adhere to FN. Anti-beta1 and alpha5 integrin antibodies strongly inhibited cell adhesion to FN in CM-MC and CoMS and moderately inhibited cell adhesion in VI-MC. Only VI-MC adhered to laminin (LN) under activation by TPA. Anti-beta1 integrin antibodies strongly inhibited cell adhesion to LN, but all anti-alpha integrin antibodies failed to inhibit cell adhesion to LN. No cells adhered to collagen types I and IV. Canine MCT cells from different origins expressed similar integrin patterns; however, there were some differences in adhesive behavior in response to various ECM proteins and activating stimuli.     

Isolation of a viable but non-culturable suppression mutant of Vibrio vulnificus: role of antioxidant enzymes in surviving stationary phase and low temperatures

ABSTRACT:   The viable but non-culturable (VBNC) suppression mutant was isolated. Suppression subtractive hybridization was used to identify differentially expressed genes among cDNA of the VBNC suppression mutant and the wild-type strain. RpoS-dependent catalase was highly expressed from the VBNC suppression mutant during oxidative stress in the stationary phase and at low temperatures. In experiments of H₂O₂ sensitivity, the VBNC suppression mutant showed a peroxide-resistant phenotype in the stationary phase and at low temperatures. These results suggest that VBNC suppression mutant cells use catalase for protection against oxidative stress in the stationary phase and at low temperatures.     

Seasonal and diurnal CO2 efflux from red wood ant (Formica aquilonia) mounds in boreal coniferous forests

Organic mounds of the red wood ants (Formica rufa group; RWA) have been shown to be “hot spots” of carbon dioxide (CO₂) efflux from the European forest soils. However, little information is available on the variability of CO₂ effluxes from RWA mounds and on the factors regulating CO₂ efflux. We assessed the seasonal and diurnal changes in CO₂ effluxes, temperatures and volumetric water contents from mounds of Formica aquilona, the important RWA of the boreal forests in Finland. The daily average CO₂ efflux from RWA mounds ranged 1.1-6.9 g CO₂ m⁻² h⁻¹ during the active ant season (May-September), and from 0.2 to 1.1 g CO₂ m⁻² h⁻¹ during their dormant period (October-April). Mound CO₂ efflux from May to September was 3.6-6.0 times higher than from the surrounding forest floors, and most likely came from RWA respiration. Seasonal changes in mound CO₂ effluxes were significantly correlated with mound temperature, but not with volumetric water content (7% on average). The high CO₂ efflux associated with increased volumetric water content (up to 34%) after a RWA mound was abandoned indicated that these dry mound conditions restrict microbial decomposition of mound organic matter. CO₂ effluxes were highest at night and lowest during the day, which is likely due to an increased ant activity or numbers in the mound at night. Diurnal changes in mound CO₂ efflux were negatively correlated with air temperature, and positively correlated with the difference between the mound and air temperature. This suggests that thermal convection of warmer mound air to the colder outside air at night might be also a cause of the diurnal changes. We conclude that seasonal and diurnal variations in mound CO₂ effluxes are dependent on RWA activities and fluctuation in RWA mound and outside temperatures.     

Factors causing variation in fine root biomass in forest ecosystems

Fine roots form one of the most significant components contributing to carbon cycling in forest ecosystems. We study here the effect of variation in root diameter classes, sampling depth and the inclusion of understorey vegetation root biomass in fine root biomass (FRB) estimates. The FRB estimates for different forest biomes are updated using a database of 512 forest stands compiled from the literature. We also investigate the relationships between environmental or forest stand variables and fine root biomass (≤2 mm in diameter) at the stand (g m⁻²) and tree level (g tree⁻¹). The FRB estimates extrapolated for the whole rooting depth were 526 ± 321 g m⁻², 775 ± 474 g m⁻² and 776 ± 518 g m⁻² for boreal, temperate and tropical forests, respectively, and were 26-67% higher than those based on the original sampling depths used. We found significant positive correlations between ≤1 and ≤2 mm diameter roots and between ≤2 and ≤5 mm roots. The FRB estimates, standardized to the ≤2 mm diameter class, were 34-60% higher and 25-29% smaller than those standardized to the ≤1 mm and ≤5 mm diameter classes, respectively. The FRB of the understorey vegetation accounted for 31% of the total FRB in boreal forests and 20% in temperate forests. The results indicate that environmental factors (latitude, mean annual precipitation, elevation, temperature) or forest stand factors (life form, age, basal area, density) can not explain a significant amount of the variation in the total FRB and a maximum of 30% that in the FRB of trees at the stand level, whereas the mean basal area of the forest stand can explain 49% of the total FRB and 79% of the FRB of trees at the tree level.