Methionine Sulfoxide Reductase A (MsrA) Deficient Mycoplasma genitalium Shows Decreased Interactions with Host Cells

Mycoplasma genitalium is an important sexually transmitted pathogen that affects both men and women. In genital-mucosal tissues, it initiates colonization of epithelial cells by attaching itself to host cells via several identified bacterial ligands and host cell surface receptors. We have previously shown that a mutant form of M. genitalium lacking methionine sulfoxide reductase A (MsrA), an antioxidant enzyme which converts oxidized methionine (Met(O)) into methionine (Met), shows decreased viability in infected animals. To gain more insights into the mechanisms by which MsrA controls M. genitalium virulence, we compared the wild-type M. genitalium strain (G37) with an msrA mutant (MS5) strain for their ability to interact with target cervical epithelial cell lines (HeLa and C33A) and THP-1 monocytic cells. Infection of epithelial cell lines with both strains revealed that MS5 was less cytotoxic to HeLa and C33A cell lines than the G37 strain. Also, the MS5 strain was more susceptible to phagocytosis by THP-1 cells than wild type strain (G37). Further, MS5 was less able to induce aggregation and differentiation in THP-1 cells than the wild type strain, as determined by carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling of the cells, followed by counting of cells attached to the culture dish using image analysis. Finally, MS5 was observed to induce less proinflammatory cytokine TNF-α by THP-1 cells than wild type G37 strain. These results indicate that MsrA affects the virulence properties of M. genitalium by modulating its interaction with host cells

Low cost overdrilling technology for pasture establishment

Paper presented at the 53rd New Zealand Grassland Association Conference, 5-7 November 1991, Whakatane.A prototype strip seeder was developed to establish grasses and legumes in the semi-arid and montane environments of the Mackenzie Basin and Central Otago. Specifications of the strip-seeder required for cost-effective performance were identified on the basis of previous direct drilling investigations in this environment, and included: (a) removal of a strip of existing vegetation to reduce competition; (b) creation of seed bed tilth; (c) controlled and separate placement of seed and fertiliser; and (d) compaction of the drilled seed bed to enhance contact between seed and soil. The prototype strip seeder was built around a modified Duncan 730 multi-seeder chassis, and was used to install spring and autumn trials at Eamscleugh in Central Otago and at Ohau Downs in the Mackenzie Basin. Mechanical improvements were made as the trials progressed. The experience gained, and results from the trials, confirm the suitability of the prototype strip seeder concept for successfully introducing grasses and legumes into this terrain

Comparison of pasture establishment from a conventional disc drill and a prototype strip seeder drill

Paper presented at the 53rd New Zealand Grassland Association Conference, 5-7 November 1991, Whakatane.Establishment of grasses and legumes drilled in spring with a prototype strip seeder drill or a conventional tripledisc drill were compared on two sites in the presence and absence of paraquat. On the Earnscleugh site, plant establishment in autumn, as a percentage of viable seed sown, was higher with the prototype drill than with the triple disc drill in the absence of paraquat. The application of paraquat increased establishment with the triple disc drill and differences between the drills were not consistent over species. Paraquat had no discernible effect on the competing vegetation or establishment at Ohau Downs. Establishment of birdsfoot trefoil, cocksfoot and tall fescue, but not alsike clover, was significantly higher in autumn in the prototype drill treatment. Treatment effects on standing herbage mass on both sites followed a similar trend to establishment although paraquat increased herbage mass in the prototype drill treatments on Earnscleugh, in contrast to the nonsignificant effect on establishment. The present results indicate the potential of the prototype strip seeder drill for cost effective establishment of improved pasture species in difficult environments