Detection of the meq gene in the T cell subsets from chickens infected with Marek's disease virus serotype 1

The meq gene was thought to be only detected in Marek's disease virus serotype 1 (MDV 1) including a very virulent strain, Md5, while L-meq, in which a 180-bp sequence is inserted into the meq open reading frame, is found in other strains of MDV 1, such as CVI 988/R6. However, both meq and L-meq were previously detected by PCR in chickens infected with MDV 1, suggesting that MDV 1 may consists of at least two subpopulations, one with meq, the other with L-meq. To further analyze these subpopulations, we analyzed the time course changes in distribution of these subpopulations among T cell subsets from chickens infected with MDV 1. Both meq and L-meq were detected in CD4+ and CD8+ T cells infected with strain Md5 or CVI 988/R6. The shift in MDV subpopulations from one displaying meq to the other displaying L-meq and/or the conversion from meq to L-meq occurred mainly in the CD8+ T cell subset from Md5-infected chickens. PCR products corresponding to L-meq rather than meq were frequently amplified from the CD8+ T cell subset from CVI 988/R 6 -infected chickens. These results suggest that a dominant subpopulation of MDV 1 changes depending on the T cell subsets, and that L-meq is dominantly present in the CD8+ T cells which play a role in the clearance of pathogenic agents.     

Evaluation of krill (Euphausia superba) meal as a partial replacement for fish meal in rainbow trout (Oncorhynchus mykiss) diets

We studied partial replacement of fish meal (FM) by krill meal (KM) and how fluoride from KM enriched-muscles and bones of rainbow trout reared in freshwater affected these fish. Diets that replaced FM with KM at proportions of 0, 7, 15 and 30% (control, KM7, KM15, and KM30) were fed to groups of rainbow trout for 92 days and growth was observed. In fish fed KM7 and KM15, weight gain (WG), feed intake (FI) and specific growth rate (SGR) were unchanged compared with fish fed the control diet, but in fish fed KM30, WG, FI and SGR significantly decreased. After the experiment, fluoride concentration in dorsal muscles of each experimental group was below the detected limit (1 mg/kg), but in vertebral bones, the fluoride concentration increased with each increase in KM inclusion in the diets: 490 mg/kg (control), 755 mg/kg (KM7), 1100 mg/kg (KM15), and 2400 mg/kg (KM30). Tissue specimens of liver of each experimental group had no histopathological changes. Therefore, accumulation of fluoride in vertebral bones apparently adversely affected growth of the vertebral bones thus affecting the growth performance as shown by the decrease in WG, FI and SGR.     

Cross-mating of euryhaline rotifer Brachionus plicatilis strains as a means to develop useful strains for larval fish food

In the field of live food science, newly inbred strains resulting from cross-mating are of interest, especially if these strains have valuable characteristics, such as high fecundity or suitable size for the mouth of larvae. We conducted cross-mating trials using Japanese and German strains of Brachionus plicatilis and reproductive parameters were characterized and compared among their progenies. Two hybrid strains A and B were obtained from the cross-mating between a Japanese female and German male, and between a German female and Japanese male, respectively. Percent mictic female production and fertilization in both hybrid strains were lower (0%), compared with the parental strains (16.7-78.4%). Strain A did not reproduce sexually, but was capable of asexual reproduction. Higher population growth was observed in the hybrid strains within crosses relative to parents. The population growth rates of parental strains were 0.31, while those of hybrid strains ranged from 0.35 to 0.37. Lorica length of hybrid strains was intermediate between the two parental strains. Using the cross-mating technique, it may be possible to produce new rotifer strains with phenotypes useful to aquaculturists.     

Ultrastructural study on interaction between a sterile,white endophytic fungus and eggplant roots

Eggplant roots colonized by a sterile, white mycelial endophyte (SWM) were previously found to become highly resistant to Verticillium wilt. SWM alone, however, caused no visible, disease symptoms, such as wilting or necrosis. The mechanism of the symptomless infection by SWM was investigated in this study. Electron microscopy revealed that hyphae of SWM were abundant on and inside the root epidermal cells 2 weeks after inoculation. Many terminal appressoria formed from apical tips of hyphae, and heavy degradation of the host cell walls was evident where hyphae accumulated. By 4 weeks following inoculation, penetration pegs easily breached epidermal cells, and the infection hyphae penetrated outer cortical cells. In response to the hyphal ingress, numerous tubule-like vesicles and membrane-bound, multivesicular bodies accumulated in cortical cytoplasm near the infection sites of the outer cortical cells, but no visible signs of the host reactions were seen in the epidermal cells. Papillae developed at the spaces between cell walls and plasma membranes at the infection sites. The penetration hyphae often grew out of the papillae, but further hyphal ingress was halted in the middle cortical cell layer. By 8 weeks following inoculation, papillae that developed in these cells contained larger amounts of highly electron-dense material and were reinforced by multilamellate, fibrous elements. Hyphae that entered such papillae were confined to them, and the hyphal cytoplasm degenerated. As the result of the activated resistance reactions, root vascular cylinders remained intact, and the host plants did not wilt.     

Correlations of the electrophysiological activity of neonicotinoids with their binding and insecticidal activities

The electrophysiological actions of various neonicotinoids, including substituted benzyl derivatives, against recombinant Drosophila SAD/chicken beta2 hybrid nicotinic acetylcholine receptor (nAChR) were measured to analyze the relationships between the in vivo (insecticidal) and in vitro (binding and agonist) activities. Most of the neonicotinoids tested were capable of inducing inward currents by activating the hybrid nAChRs expressed in Xenopus laevis oocytes, whereas some compounds had no agonist activity and only blocked the acetylcholine-induced currents. Variations in the agonist activity were well correlated with those in the binding potency evaluated using [3H]imidacloprid as well as insecticidal activities.     

Suppression of rice blast using freeze-killed mycelia of biocontrol fungal candidate MKP5111B

Several applications of the suppressive fungus MKP5111B, isolated from the phylloplane of rice plants, were tested in an effort to control rice blast disease. Three treatments with MKP5111B [living (Std), killed with liquid nitrogen (FR), and autoclaved (AC)] were either sprayed onto rice seedlings or mixed into seed-sown soil. Three weeks after spraying and 4 weeks after the soil application, we introduced Magnaporthe oryzae, the causal agent of rice blast, into our systems. The Std and FR treatments suppressed rice blast, but the AC treatment proved ineffective. Although a suppressive effect was seen on new leaves, no mycelium of MKP5111B was seen. The fungus thus may have induced a systemic resistance in the rice plants. A substance from MKP5111B, such as elicitor molecule(s) are likely responsible for the induced resistance.     

First report of spinach downy mildew caused by race Pfs:8 of <Emphasis Type="Italic">Peronospora farinosa</Emphasis> f. sp. <Emphasis Type="Italic">spinaciae</Emphasis> in Japan

The race of field isolates of Peronospora farinosa f. sp. spinaciae (Pfs), causal agent of spinach downy mildew, were identified using race-differential cultivars. One isolate was similar to race Pfs:6. Three isolates were identified as race Pfs:8, the first time the race has been reported in Japan as far as we know. The differential reaction caused by the other two isolates did not match any known to be caused by races Pfs:1 through Pfs:11; thus, this strain appears to a new pathogenic strain in Japan.     

Enhancement of interleukin-2 production by bovine peripheral blood mononuclear cells treated with the combination of anti-programmed death-ligand 1 and cytotoxic T lymphocyte antigen 4 chimeric monoclonal antibodies

Our previous studies demonstrate the therapeutic efficacy against bovine diseases of an anti-bovine programmed death-ligand 1 (PD-L1) chimeric antibody. In humans, PD-1 and PD-L1 antibodies are more effective when combined with an antibody targeting cytotoxic T lymphocyte antigen 4 (CTLA-4) and these combination therapies are therefore clinically used. Here we generated an anti-bovine CTLA-4 chimeric antibody (chAb) to enhance the therapeutic efficacy of the PD-L1 antibody. We further analyzed the effects of dual blockade of CTLA-4 and PD-1 pathways on T-cell responses. The established anti-bovine CTLA-4 chAb showed comparable blocking activity on the binding of bovine CTLA-4 to CD80 and CD86 as the anti-bovine CTLA-4 mouse monoclonal antibody. Anti-bovine CTLA-4 chAb also significantly increased IL-2 production from bovine peripheral blood mononuclear cells (PBMCs). Further, the combination of anti-CTLA-4 chAb with anti-PD-L1 chAb significantly upregulated IL-2 production by PBMCs. These results suggest that the combination of antibodies have higher potential to enhance immune responses against pathogens compared with single administration.     

Phosphorus status of some paddy soils in Bangladesh

Abstract

Phosphorus status of Bangladesh paddy soils covering the major paddy soil types was assessed in terms of parent materials and physiography. Total P concentration ranged from 172 to 604 mg kg^?1 in the topsoil and from 126 to 688 mg kg^?1 in the subsoil, and varied with the physiography to which the soils belonged. In most soils, the available P concentration was much higher for the topsoil than for the subsoil. The inorganic P concentration was higher than the organic P concentration, except for one soil series from the Old Himalayan Piedmont Plain, and was significantly and positively correlated with the total P concentration. Among the inorganic forms, only the concentration of Al-bound P showed a significant correlation with that of available P based on the Bray P-2 method in both topsoil and subsoil. In general, the P status was critically low in paddy soils of the terrace area. Normal growth of paddy rice in this area is expected to be difficult without application of P fertilizer.