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Grasslands across the globe are undergoing expansive degradation due to human impacts and climate change. If restoration of degraded native grassland is to be achieved at the scale now required, cost-effective means for seed-based establishment of grass species is crucial. However, grass seeds present numerous challenges associated with handling and germination performance that must be overcome to improve the efficiency of seeding. Previous research has demonstrated that complete removal of the palea and lemma (husk) maximises germination performance, hence we investigated the effects of complete husk removal on seed handling and germination of four temperate Australian grass species. Three techniques were tested to remove the husk - manual cleaning, flaming or acid digestion (the latter two followed by a manual cleaning step); these techniques were refined and adapted to the selected species, and germination responses were compared. The complete removal of the husk improved seed handling and sowability for all species. Germination was improved in Microlaena stipoides by 19% and in Rytidosperma geniculatum by 11%. Of the husk removal methods tested, flaming was detrimental to seed germination and fatal for one species (R. geniculatum). Compared to manual cleaning, sulphuric acid improved the overall efficacy of the cleaning procedure and increased germination speed (T50) in Austrostipa scabra, Chloris truncata and M. stipoides, and improved final germination in R. geniculatum by 13%. The seed processing methods developed and tested in the present study can be applied to grass species that present similar handling and germination performance impediments. These and other technological developments (seed coating and precision sowing) will facilitate more efficient grassland restoration at large scale., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

RG 12525 (2-[[4-[[2-(1H-tetrazole-5-ylmethyl)phenyl]methoxy]phenoxy]methyl] quinolone) is a novel peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonist. In vitro microsomal inhibition assays indicated that RG 12525 is a potent inhibitor of CYP3A4, with a Ki value of 0.5 microM. With the conservative assumption that the total plasma concentration of drug was available to metabolic enzymes following RG 12525 oral administration, marked inhibition of CYP3A4 was expected to substantially reduce the systemic clearance of compounds metabolized by this enzyme. The possibility also existed for inhibition of intestinal and hepatic CYP3A4 by RG 12525 to reduce "first-pass" metabolism and increase absolute bioavailability of CYP3A4 substrates orally coadministered. Consequently, an in vivo drug-drug interaction study was performed to evaluate the effects of orally administered RG 12525 on in vivo CYP3A4 activity in healthy male subjects. The pharmacokinetics of oral midazolam, a probe for intestinal and hepatic CYP3A activity, was not influenced by either the low (100 mg qd for 4 days) or high (600 mg qd for4 days) RG 12525 dosing regimen despite the resulting total plasma concentrations of inhibitor that were well above in vitro Ki values. The point estimates and 90% confidence intervals for the ratios of mean midazolam AUC for subjects administered 100 mg RG 12525 (110.6; 98.7-124.1) and 600 mg RG 12525 (98.4; 84.4-114.7) versus midazolam alone were within 80% to 125%. To explain these results, factors that could limit the accuracy of in vitro models in predicting metabolic drug interactions, mainly the high degree of RG 12525 protein binding (> 99.9%), were considered. The lack of correlation between the in vitro inhibition of CYP3A4 by RG 12525 and the inconsequential effects of this compound on midazolam pharmacokinetics accentuate the need to recognize factors other than plasma drug concentrations and potency of in vitro enzyme inhibition when extrapolating in vitro data to predict in vivo drug-drug interactions.