Concentrations and specific antibodies to staphylococcal enterotoxin-C and toxic shock syndrome toxin-1 in bovine mammary gland secretions,and inflammatory response to the intramammary inoculation of these toxins

To investigate the pathological role of staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin-1 (TSST-1) in bovine mastitis, the production of SEs and TSST-1 was investigated in staphylococci isolated from 120 mammary gland secretions (MGS, 51 from no clinical sign-mammary glands and 69 from staphylococcal mastitic-mammary glands) collected from dairy farms where staphylococcal mastitis frequently occurred in Miyagi and Yamagata prefectures from 1997 to 1998. Concentrations of these toxins and specific antibody titers in each MGS were also measured. Furthermore, SEC and TSST-1 were inoculated into lactating mammary glands and inflammatory responses were analyzed. A high percentage of staphylococci including Staphylococcus aureus and coagulase-negative staphylococci isolated from both no clinical sign- and mastitic-MGS produced both SEC and/or TSST-1. The concentration of SEC increased with the severity of the mastitis, and was significantly higher (P<0.05) in acute mastitic-than in no clinical signs-MGS. Titers of specific antibodies to TSST-1 in MGS were significantly higher (P<0.05) than those to SEC, regardless of whether or not the cows were lactating or mastitic. Specific antibodies purified from MGS neutralized each toxin in vitro. A significant increase (P < 0.05) in somatic cell counts was induced by the intramammary inoculation of SEC but not TSST-1. These findings indicated that SEC rather than TSST-1 plays an important role in the pathology of staphylococcal bovine mastitis. The inflammatory activity of TSST-1 was probably neutralized by specific antibodies in MGS.     

Effect of propylene glycol and undegradable protein source on rumen fermentation, blood metabolism and milk production in lactating dairy cows

Eight lactating Holstein cows were divided into two groups ( n  = 4) and used in a double reversal trial with three periods of 14 days each, to evaluate diets containing propylene glycol (PG) and ruminally undegradable protein (RUP) blend on milk yield and composition, ruminal fermentation and blood metabolism. The control diet contained 20% chopped Sudangrass hay, 20% cubed alfalfa hay, 12% corn silage, and 48% of the respective concentrate mixtures (dry matter basis). The experimental diet (PG + RUP) partially replaced the concentrate mixture from the control diet with 1.4% PG and 2.1% RUP. Both diets contained about 16% crude protein and 71% total digestible nutrients. Dry matter intake was similar between the two diets. Daily production of milk, milk lactose and milk solids-not-fat increased by 9.0%, 11.3% and 9.3%, respectively ( P  < 0.1), for cows fed diets with PG + RUP; milk composition was unchanged. Although the concentration of ruminal total volatile fatty acids was unchanged, the proportion of propionic acid increased, and the proportion of acetic acid decreased with PG + RUP. The concentration of ruminal ammonia nitrogen and number of ciliate protozoa was not significantly affected by PG + RUP. The concentration of glucose in blood plasma increased, the concentration of urea nitrogen was unaffected, and the concentration of some essential free amino acids decreased with PG + RUP. It is suggested that these changes might be caused predominantly by PG, and the addition of PG may exert a favorable effect on milk production through increased metabolism.     

Effects of AI protocol and time interval from onset of estrus to AI on conception rate in Japanese Black cows

Two different artificial insemination (AI) protocols were investigated to determine the effect of the time interval from the onset of estrus (as detected by a pedometer) to the AI on the conception rate in Japanese Black cows. Seventy‐three cows were divided into two groups that received AI either after the induction of synchronized ovulation (synchronized AI group; n = 26) or at the time of observed estrus (control AI group; n = 47). Each group was further divided into two subgroups, which were artificially inseminated either 0–12 h (early AI group; n = 21) or 12–24 h (late AI group; n = 52) after the onset of estrus. There was no significant difference in the conception rate between the synchronized AI and control AI groups. The AI protocol and the detection of estrus using a threshold of counted steps (as measured by a pedometer) in this study could be effective for planned reproduction management without the observation of standing estrus in Japanese Black cows.     

In Vitro Activities of Antifungal Agents against Clinical Isolates of Dermatophytes from Animals

Although the susceptibility of dermatophytes to antifungal drugs is well documented in humans, the effectiveness in animals has not been previously investigated. The in vitro susceptibility of 54 clinical isolates from animal dermatophytoses to ketoconazole (KTZ), itaconazole (ITZ) and terbinafine (TFN) was measured using microdilution assay (CLSI M38-A2 test) and by the E-test (KTZ and ITZ). All 3 drugs showed antifungal activity, while KTZ displayed the broadest minimum inhibition concentration (MIC) range (0.125-16 μg/ml) against M. canis and M. gypseum. The MIC of KTZ and ITZ was almost the same for human and animal isolates of T. mentagrophytes and T. rubrum. The MIC of TFN was almost the same for dermatophytes isolated from humans and animals.     

Porcine MHC classical class I genes are coordinately expressed in superantigen-activated mononuclear cells

The expression of the major histocompatibility complex (MHC) classical class I genes is important for the adaptive immune response to target virus-infected cells and cancer cells. The up-regulation of the MHC is achieved by hormonal/cytokine signals including IFN-γ-inducible elements. The swine leukocyte antigen (SLA), the MHC class I region of pigs, consists of the duplicated classical class I genes, SLA-1, SLA-2 and SLA-3, but the molecular mechanisms involved in their up-regulation after T cell stimulation have not been fully elucidated. In order to better understand some of the putative regulatory mechanisms of SLA class I gene expression in activated T cells, we examined the coordinated expression of the SLA classical class I, IFN-γ and interferon regulatory factor-1 (IRF-1) genes in the peripheral blood mononuclear cells (PBMCs) of SLA homozygous Clawn miniature swine stimulated for 72h with either IFN-γ or an enterotoxin produced by Staphylococcus aureus. This enterotoxin, toxic shock syndrome-1 (TSST-1), is known to act as a superantigen (sAG) to activate the T cells in various vertebrate species. We showed by using mAbs and flow cytometry that the CD4(+)CD25(+) cell number of swine PBMCs was also increased by TSST-1 and to a lesser degree by IFN-γ. Time course analyses of the expression of the IFN-γ, IRF-1 and the three classical class I genes, SLA-1, SLA-2, and SLA-3, in PBMCs by quantitative real-time PCR revealed a transitory response to TSST-1 or IFN-γ stimulation. The IFN-γ mRNA levels in the PBMCs were continuously up-regulated over the first 48h by TSST-1 or IFN-γ. In contrast, SLA class I expression moderately increased at 24h and then decreased to a baseline level or less at 72h of IFN-γ or TSST-1 stimulation. The three classical SLA class I genes showed similar expression kinetics, although SLA-3 mRNA level was consistently lower than those of SLA-1 and -2. The expression of IRF-1, a modulator of SLA expression, showed similar kinetics to those of the three classical SLA class I genes. The expression profiles detected by flow cytometry of the SLA molecules on the cell surface of PBMCs were maintained at a consistently high level during cell stimulation with either TSST-1 or IFN-γ, which was distinct from the kinetics of mRNA expression. These results showed that miniature swine SLA class I mRNA expression was effectively and equally up-regulated among the three loci and coordinately with IRF-1 gene expression after stimulation of T cell activation by sAG or IFN-γ.     

The role of primary germ tubes in the life cycle of Blumeria graminis: The primary germ tube is responsible for the suppression of resistance induction of a host plant cell

When the conidia of Blumeria graminis f. sp. hordei (Bgh) are inoculated on barley coleoptile cells they produce short germ tubes called primary germ tubes (PGTs) about 2 h after inoculation. We evaluated the positive role of a PGT in inducing accessibility of the host cell under the germ tube. When an appressorium (APP) penetrated the same cell on which a PGT was present, the ratio of haustorium formation (penetration efficiency) was significantly higher than when an APP penetrated the cell adjacent to the one on which a PGT was present. When an APP penetrated the cell laterally adjacent to the one on which a PGT was present we killed the cell under the PGT by puncturing it with a microneedle and then investigated the penetration efficiency of the cell adjacent to the dead cell. As a control we killed the cell longitudinally adjacent to the one on which a PGT was present and investigated the penetration efficiency of the laterally adjacent cell. The results showed that the penetration efficiency of the former was significantly lower than that of the latter. This suggests that some accessibility factor might transfer from a cell on which a PGT is present to a laterally adjacent cell. The existence of a conidium body but not a PGT was not effective for induced accessibility of the host cell. Moreover, when a Bgh germling was removed 6 h after inoculation and another germling was transferred to the same cell, the penetration efficiency was significantly higher than that of control. As a control, a Bgh germling was transferred to a cell on which no germling was present. These results suggest that the existence of PGT is effective for induced accessibility of a host cell when penetrated by Bgh. However, it is unclear whether or not a PGT secretes some substance(s) which suppresses the resistance induction of a host cell.     

Induced resistance in tomato plants to the toxin-dependent necrotrophic pathogen Alternaria alternata

A necrotrophic pathogen, the tomato pathotype of Alternaria alternata (Aa) causes Alternaria stem canker on tomato. Its pathogenicity depends on the production of host-specific AAL-toxin. Pre-inoculation with nonpathogenic Aa or pretreatment an elicitor prepared from Aa reduced disease symptoms by the pathogen. Salicylic acid (SA)- and jasmonic acid (JA)-dependent defense responses in tomato are not involved in the resistance to the pathogen induced by nonpathogenic Aa. The results suggest that an alternative and unknown signaling pathway independent of SA- and JA-signaling might modulate the induced resistance by activating the expression of the multiple defense genes.