Macrolides and lincomycin susceptibility of Mycoplasma hyorhinis and variable mutation of domain II and V in 23S ribosomal RNA

A total of 151 strains of Mycoplasma hyorhinis isolated from porcine lung lesions (weaned pigs, n=71, and finishers, n=80) were investigated for their in vitro susceptibility to 10 antimicrobial agents. Thirty-one strains (28 from weaned pigs and 3 from finishers) showed resistance to 16-membered macrolide antibiotics and lincomycin. The prevalence of the 16-membered macrolide-resistant M. hyorhinis strain in weaned pigs from Japanese herds has approximately quadrupled in the past 10 years. Several of the 31 strains were examined for mutations in the 23S ribosomal RNA (rRNA). All field strains tested showed a transition of A to G at position 2059 of 23S rRNA-rendered Escherichia coli. On the other hand, individual tylosin- and lincomycin-resistant mutants of M. hyorhinis were selected in vitro from the susceptible type strain BTS7 by 3 to 9 serial passages in subinhibitory concentrations of each antibiotic. The 23S rRNA sequences of both tylosin and lincomycin-resistant mutants were compared with that of the radical BTS7 strain. The BTS7 mutant strain selected by tylosin showed the same transition as the field-isolated strains of A2059G. However, the transition selected in lincomycin showed mutations in domains II and V of 23S rRNA, G2597U, C2611U in domain V, and the addition of an adenine at the pentameric adenine loop in domain II. The strain selected by lincomycin showed an additional point mutation of A2062G selected by tylosin.     

Immunopathological investigations on bovine digital epidermitis

Paraffin-embedded fragments of bovine digital skin lesions were sectioned and stained with Warthin-Starry, haematoxylin and eosin, Grocott's methenamine silver and immunohistochemical techniques. Microorganisms observed in the silver-stained sections were classified into four major morphological groups. Spirochaetes were the most prevalent organisms, but bacillary and coccoid elements were also present in most sections. Immunohistochemical probing demonstrated that approximately 80 per cent, 46 per cent and 41 per cent of the digital and interdigital dermatitis sections stained positively with polyclonal antisera to Treponema pallidum, Campylobacter jejuni and Fusobacterium necrophorum, respectively. An unidentified branching filamentous organism (presumed to be an actinomycete) was consistently present in the sections of samples from mild interdigital lesions.     

Microconidia act the role as spermatia in the sexual reproduction of <Emphasis Type="Italic">Botrytis cinerea</Emphasis>

In the sexual reproductive cycle of Botrytis cinerea, large numbers of microconidia were observed in all the crosses that formed sexual bodies. To clarify the role of the microconidia in sexual reproduction, they were separated using a sucrose density gradient and then used in crossing tests with fungal sclerotia. Sexual bodies were formed in all the crosses in the five mating combinations, demonstrating that microconidia are able to function as spermatia during sexual reproduction of B. cinerea.     

Increased expression of fractalkine and its receptor CX(3)CR1 in canine inflammatory bowel disease and their possible role in recruitment of intraepithelial lymphocytes

The interaction between fractalkine/CX(3)CL1 and its receptor CX(3)CR1 has been reported to play an important role in various human inflammatory diseases, including inflammatory bowel disease (IBD) mediated by lymphocyte chemoattraction. The objective of this study was to investigate the role of fractalkine and CX(3)CR1 in lymphocyte migration in canine IBD. IBD was diagnosed in 34 dogs, and 19 healthy beagles were used as normal controls. We quantified intestinal mRNA and protein expression of fractalkine and CX(3)CR1 by real-time RT-PCR and ELISA, respectively, and examined the localization of fractalkine in canine intestine by immunohistochemistry. The expression of CX(3)CR1 and surface antigens on peripheral blood mononuclear cells (PBMCs) and intraepithelial lymphocytes (IELs) was analyzed by flow cytometry. Intestinal fractalkine and CX(3)CR1 mRNA was significantly up-regulated in IBD dogs compared with the healthy control dogs. In addition, fractalkine expression on intestinal epithelial cells was significantly increased in the intestinal mucosa of IBD dogs compared with the healthy dogs. CX(3)CR1(+) PBMCs were significantly elevated in IBD dogs and positively correlated with the histopathological severity of IELs infiltration. These CX(3)CR1(+) PBMCs predominantly expressed markers for cytotoxic T cells. Almost all IELs expressed CD3, and the majority of cells expressed CD8 rather than CD4, which was analogous to the CX(3)CR1(+) PBMCs. These results suggest that the fractalkine-CX(3)CR1 interaction may contribute to the pathogenesis of canine IBD through migration of IELs.     

Adenosine and ATP affect LPS-induced cytokine production in canine macrophage cell line DH82 cells

Macrophages are essential for controlling the majority of infections, and are mediators of natural immunity. During infection, lipopolysaccharide (LPS) stimulates macrophages to produce pro-inflammatory cytokines. Adenosine and ATP released into the extracellular space by immunological stimuli have been shown to regulate various immune functions. More recently, it has been shown adenosine and ATP have a critical role on the physiological negative feedback mechanism for limitation and termination of tissue-specific and systemic inflammatory responses. It was useful and meaningful to gain information about interaction between LPS, which generates the inflammation, and adenosine and ATP, which terminate the inflammation. We evaluate effects of adenosine and ATP on the production of cytokines related to inflammation in canine macrophage cell line DH82 cells. Adenosine and ATP respectively increased the production of IL-10 without affecting the production of IL-6, TNF-α and IL-12 in DH82 cells. In addition, adenosine and ATP prevented the production of LPS-induced IL-6, TNF-α and IL-12 in DH82 cells. In contrast, adenosine and ATP potentiated LPS-induced IL-10 production in DH82 cells. Moreover, adenosine, but not ATP inhibited LPS-induced expression of TLR4 in DH82 cells. These results suggest that conditions related to increased adenosine and/or ATP may play an important role in the inflammatory reactions.     

Regulation of root-to-leaf Na and Cl transport and its association with photosynthetic activity in salt-tolerant soybean genotypes

ABSTRACT

Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO₂ assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO₂ concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding.     

Hypereosinophilic syndrome in two cats

Two cats showing chronic vomiting, diarrhea and weight loss were found to have leukocytosis with marked eosinophilia. Both cats were diagnosed with hypereosinophilic syndrome by the findings of increased eosinophils and their precursors in the bone marrow, eosinophilic infiltration into multiple organs, and exclusion of other causes for eosinophilia. Although cytoreductive chemotherapy with hydroxycarbamide and prednisolone was performed, these two cats died 48 days and 91 days after the initial presentation.     

Insecticidal and neuroexciting actions of DDT analogs

The neuroexciting activity of DDT and its analogs to produce repetitive responses on the nerve cord of Periplaneta americana was determined using the extracellular electrode method. The convulsive activity on P. americana and the insecticidal effect on Callosobruchus chinensis were also examined. It was found that the convulsive and insecticidal activities increase almost proportionally with increase in the neuroexciting activity within a set of p,p′-substituted DDT analogs. The intimate connections among these biological effects suggest that symptoms such as convulsion and death caused by DDT analogs are closely related with their neuroexcitory effect and there is a common mode of action in spite of differences in insect species.     

Modeling aerobic decomposition of rice straw during the off-rice season in an Andisol paddy soil in a cold temperate region of Japan: Effects of soil temperature and moisture

Submerged rice paddies are a major source of methane (CH₄) which is the second most important greenhouse gas after carbon dioxide (CO₂). Accelerating rice straw decomposition during the off-rice season could help to reduce CH₄ emission from rice paddies during the single rice-growth season in cold temperate regions. For understanding how both temperature and moisture can affect the rate of rice straw decomposition during the off-rice season in the cold temperate region of Tohoku district, Japan, a modeling incubation experiment was carried out in the laboratory. Bulk soil and soil mixed with 2% of δ¹³C-labeled rice straw with a full factorial combination of four temperature levels (?5 to 5, 5, 15, 25°C) and two moisture levels (60% and 100% WFPS) were incubated for 24 weeks. The daily change from ?5 to 5°C was used to model the freezing–thawing cycles occurring during the winter season. The rates of rice straw decomposition were calculated by (i) CO₂ production; (ii) change in the soil organic carbon (SOC) content; and (iii) change in the δ¹³C value of SOC. The results indicated that both temperature and moisture affected the rate of rice straw decomposition during the 24-week aerobic incubation period. Rates of rice straw decomposition increased not only with high temperature, but also with high moisture conditions. The rates of rice straw decomposition were more accurately calculated by CO₂ production compared to those calculated by the change in the SOC content, or in its δ¹³C value. Under high moisture at 100% WFPS condition, the rates of rice straw decomposition were 14.0, 22.2, 33.5 and 46.2% at ?5 to 5, 5, 15 and 25°C temperature treatments, respectively. While under low moisture at 60% WFPS condition, these rates were 12.7, 18.3, 31.2 and 38.4%, respectively. The Q₁₀ of rice straw decomposition was higher between ?5 to 5 and 5°C than that between 5 and 15°C and that between 15 and 25°C. Daily freezing–thawing cycles (from ?5 to 5°C) did not stimulate rice straw decomposition compared with low temperature at 5°C. This study implies that to reduce CH₄ emission from rice paddies during the single rice-growth season in the cold temperate regions, enhancing rice straw decomposition during the high temperature period is very important.