Vertical transmission of bovine leukemia virus and bovine immunodeficiency virus in dairy cattle herds.

Vertical transmission of bovine leukemia virus (BLV) and bovine immunodeficiency virus (BIV) was investigated in five dairy cattle herds in Hokkaido, where 36.1 and 17.0% of cattle were BLV and BIV seropositive, respectively, and 9.9% of dams were co-infected with both BIV and BLV. Twenty six cases of offspring born from dams infected with only BLV (17 cases) or with both BIV and BLV (9 cases) were examined for the presence of BLV and BIV before and after colostrum feeding by polymerase chain reaction (PCR) and syncytium assay. After birth, all calves were separated immediately from their dams. The offspring born from BLV-positive dams were BLV-negative before colostrum feeding, suggesting that no transplacental transmission had occurred. Thereafter, these offspring were fed colostrum or milk from their dams, but still remained BLV-negative. The other offspring born from BLV-positive dams were fed with BLV-negative colostrum, or with pasteurized BLV-positive colostrum. All these calves remained negative for BLV infection, suggesting that in utero transmission of BLV is negligible. In the case of offspring born from dams co-infected with BLV and BIV, calves were BIV-positive before colostrum feeding at 1 day after the birth, indicating in utero transmission of BIV. After colostrum feeding from their dams, newborn calves became BLV-positive. In addition, one calf was BLV-positive even before colostrum feeding. These results suggest that BIV can be transmitted to offspring in utero, and that BLV can be transmitted through colostrum or milk if dams are infected with both BIV and BLV.     

Effects of oestrogen and anti-oestrogen on the cells of the endosteal surface of male Japanese quail

1. The endosteal cellular response occurring in the early stages of medullary bone formation was histologically examined in the femurs of male Japanese quail treated with oestrogen and antioestrogen. 2. The numbers of endosteal cells decreased, and preosteoblasts and osteoblasts increased, on the endosteal surface following oestrogen treatment. 3. After oestrogen and anti-oestrogen treatment the numbers of preosteoblasts and osteoblasts on the endosteal surface did not increase. However, endosteal cells slowly decreased in number and osteoclasts increased. 4. This study demonstrates that differentiation of osteoblasts is induced by oestrogen stimulation and suggests that osteoclasts occur by oestrogen inhibition on the endosteal surface.     

Molecular cloning, sequencing and phylogenetic analysis of inflammatory cytokines of swamp type buffalo contrasting with other bubaline breeds

The current research concerned in the cloning, sequencing and phylogenetic analysis of inflammatory cytokine (IL-1alpha, IL-1beta, IL-6 and TNF-alpha) genes from swamp buffalo and two bubaline breeds, CB (cross between swamp and riverine type buffalo) and the Bulgarian Murrah buffalo. Multiple sequence comparison showed a high homology between the bubaline breeds, which ranged from 99.3% to 100.0% similarity, whereas from 98.6% to 99.0% compared to cattle. The phylogenetic analysis had confirmed and justified the degree of relationship between these bubaline species and their distinctness to each other by the bootstrap value (%) generated. These findings were discussed with particular attention to the diversity of the inflammatory cytokine proteins within closely related species. The result of this study concluded that a small difference in the cytokine structures might be the reason behind or has a contributory factor on the previous reports about the existence of disease resistance. However, in-depth study is necessary to further qualify these findings.     

Blockade of bovine PD-1 increases T cell function and inhibits bovine leukemia virus expression in B cells in vitro

Programmed death-1 (PD-1) is a known immunoinhibitory receptor that contributes to immune evasion of various tumor cells and pathogens causing chronic infection, such as bovine leukemia virus (BLV) infection. First, in this study, to establish a method for the expression and functional analysis of bovine PD-1, hybridomas producing monoclonal antibodies (mAb) specific for bovine PD-1 were established. Treatment with these anti-PD-1 mAb enhanced interferon-gamma (IFN-γ) production of bovine peripheral blood mononuclear cells (PBMC). Next, to examine whether PD-1 blockade by anti-PD-1 mAb could upregulate the immune reaction during chronic infection, the expression and functional analysis of PD-1 in PBMC isolated from BLV-infected cattle with or without lymphoma were performed using anti-PD-1 mAb. The frequencies of both PD-1⁺ CD4⁺ T cells in blood and lymph node and PD-1⁺ CD8⁺ T cells in lymph node were higher in BLV-infected cattle with lymphoma than those without lymphoma or control uninfected cattle. PD-1 blockade enhanced IFN-γ production and proliferation and reduced BLV-gp51 expression and B-cell activation in PBMC from BLV-infected cattle in response to BLV-gp51 peptide mixture. These data show that anti-bovine PD-1 mAb could provide a new therapy to control BLV infection via upregulation of immune response.     

Comparison of PCR assays for detection and quantification of Phomopsis sclerotioides in plant and soil

We developed a real-time PCR assay using a TaqMan probe (TM-qPCR) for specific detection and quantification of Phomopsis sclerotioides, causal agent of black root rot of cucurbit crops. The design of the primer sets and hybridization probe was based on the internal transcribed spacer region of the ribosomal DNA. The TM-qPCR assay was compared with a conventional, standard PCR (sPCR) assay and on a quantitative real-time PCR (SG-qPCR) assay based on SYBR Green I. The TM-qPCR assay had a detection limit of ca. 0.4 fg of P. sclerotioides DNA, which was approximately 100 times more sensitive than the sPCR assay and almost equivalent to the SG-qPCR assay. The TM-qPCR and SG-qPCR assays both were able to detect various quantities of P. sclerotioides DNA from diseased plants and infested soils, including DNA levels that were not detectable by the sPCR assay. However, the TM-qPCR was advantageous for samples containing PCR-inhibiting substances because its multiplex real-time PCR function allows the adjustment of cycle threshold values with an internal control. Based on the high specificity and sensitivity required for analyzing DNA in natural samples, the newly developed TM-qPCR assay was the most reliable tool for rapidly detecting and quantifying P. sclerotioides in plant and soil samples.     

Automated analysis of fine‐root dynamics using a series of digital images

Information related to the growth of fine roots is important for understanding C allocation in trees and the mechanisms of C cycling in ecosystems. Observations using a camera or scanner embedded in the soil enabled us to obtain continuous images of fine‐root‐growth dynamics. However, these methods are still labor‐intensive because the image analysis has to be conducted manually. We developed an automated method for tracking movement or elongation of fine roots using a sequence of scanner images. We also show how data obtained with these methods can be used for calculating fine‐root behavior. Two A4‐size scanners were buried in a mixed forest in Japan and images were taken continuously from within the soil. We preprocessed these images by extracting the fine‐root area from the images and developed an automated calculation plug‐in we named A‐root for tracking growth movement of the tips of fine roots. A‐root and manual‐tracking results were compared using the same images. The results show the A‐root and manual‐tracking methods yielded similar levels of accuracy. The average growth rate of 17 fine roots tracked using the program was 0.16 mm h^–1. The observation of the direction of growth in fine roots showed the direction may be influenced by the original root's growth where the fine roots branched, distribution of soil particles, other roots, and the force of gravity. The A‐root analysis also suggested there may be an interaction between speed of growth and changes in direction of growing fine roots.     

Involvement of jasmonic acid signalling in bacterial wilt disease resistance induced by biocontrol agent Pythium oligandrum in tomato

When the biocontrol agent Pythium oligandrum (PO) colonizes the rhizosphere, it suppresses bacterial wilt disease in tomato (Solanum lycopersicum cv. Micro‐Tom) caused by Ralstonia solanacearum, and a homogenate of its mycelia exhibits elicitor activity, inducing an ethylene (ET)‐dependent defence response in Micro‐Tom. Since salicylic acid (SA) and jasmonic acid (JA) play an important role in plant defence responses to pathogens, the involvement of SA‐ and JA‐dependent signal transduction pathways in resistance to R. solanacearum was investigated in tomato roots treated with a mycelial homogenate of PO. Bacterial wilt disease was also suppressed in tomato cv. Moneymaker treated with the PO homogenate. However, the SA‐inducible PR‐1(P6) gene was not up‐regulated in either Micro‐Tom or Moneymaker. SA did not accumulate in homogenate‐treated roots in comparison with distilled water‐treated controls, even 24 h after inoculation. Induced resistance against R. solanacearum was not compromised in SA‐non‐accumulating NahG transgenic plants treated with the PO homogenate. On the other hand, the expression of the JA‐responsive gene for the basic PR‐6 protein was induced in both tomato cultivars treated with the PO homogenate. Furthermore, quantitative disease assays showed that the induced resistance against R. solanacearum was compromized in PO homogenate‐treated jai1‐1 mutant plants defective in JA signalling. These results indicated that the JA‐dependent signalling pathway is required for PO‐induced resistance against R. solanacearum in tomato.     

Predation by neogastropods on <Emphasis Type="Italic">Turbo cornutus</Emphasis> juveniles and other small gastropods inhabiting coralline algal turfs

To understand the effects of predation by gastropods on juveniles of the Japanese spiny turban snail Turbo cornutus, a field survey and laboratory experiments were conducted. The species compositions of the order Neogastropoda inside turfs of articulated coralline algae (ACA) on the east coast of Sagami Bay were surveyed monthly, and the dominant species inside the ACA turfs were identified. Laboratory experiments were conducted to examine the effects of predation by the dominant neogastropods on small gastropods in ACA turfs. Turban snails, which inhabit ACA turfs during their juvenile stages, were predated by two muricid gastropods, Ergalatax contractus and Thais bronni, with the predation rate of E. contractus being significantly higher than that of T. bronni. While E. contractus could also predate two other species of gastropods, Anachis misera and Cantharidus japonicus, the predation rates on these two snails were significantly lower than on T. cornutus. The observed defensive behaviors were different among the three prey species, and the defensive strategy related to the calcified operculum of T. cornutus was not efficient against predation by E. contractus. It is concluded that the predation by E. contractus represents an important factor in the mortality of juvenile turban snails inside ACA turfs.