THE APPLICATION OF THE DYNAMIC TRIANGLE OLFACTOMETER TO THE EVALUATION OF ORAL ODOR

The Dynamic Triangle Olfactometer, an instrument which measuresodor thresholds by a system functionally based on the principlesof steady state dynamic flow, dilution and forced choice triangledesign, was evaluated and found to be most acceptable for itsutility in appraising the efficacy of breath freshening formulationsin relieving or controlling extrinsic (onion) oral malodor. Initially, the olfactory acuity of a panel of novice judgeswas ascertained by the development of thresholds for hydrogensulfide and methyl mercaptan, both compounds related to oralmalodor, especially extrinsic as induced by an aqueous suspensionof onion oil used in this study. The threshold for onion oilwas also established. Several breath freshening formulationswere demonstrated to be effective in controlling extrinsic oralmalodor under the conditions of this study. The operational parameters of the DTO system were uncomplicatedand the data so obtained was reproducible. The panel of judgesapproximated the distribution of olfactory sensitivity of anormal population; therefore, the performance of the formulationsas measured in this system should be, and is, reasonably predictiveto a consumer population.     

The world in a grain of sand: evolutionarily relevant,small‐scale freshwater bioregions on subtropical dune islands

1. Conservation plans are required to safeguard freshwater biodiversity in the face of increasing threats. Traditionally plans have used surrogates for biodiversity that do not account for the evolutionary process, but genetic data in the form of comparative phylogeography can fulfil this role. 2. Comparative phylogeographic analyses of multiple freshwater fish and decapod crustacean species were carried out with specimens from two model systems, namely the sand dune islands of Fraser and North Stradbroke in eastern Australia. 3. Almost all of the species studied from both islands displayed an intraspecific evolutionary split between sides of the island (east/west on North Stradbroke Island, and north/south on Fraser Island), indicating that each side of each island hosts its own distinct community of populations of freshwater animals. 4. The probable process responsible for both of these divergent communities is different source populations for each side of each island. 5. This study shows that biodiversity will not always follow obvious geography and that significant diversity may exist at small scales within multiple species. These evolutionarily relevant units of biodiversity should be incorporated at the beginning of the conservation and resource management planning process.     

The photosynthesis of ryegrass leaves grown in a simulated sward

Plants were taken from simulated swards of perennial ryegrass (Lolium perenne) grown in a controlled environment and the rates of photosynthesis of the youngest fully expanded leaves, and the second and third youngest leaves on the same tillers were measured. The youngest leaves had the highest rates and the third the lowest, with the second leaves intermediate. The rate of photosynthesis in bright light of successive youngest expanded leaves decreased as the swards increased in leaf area, but did not when plants were grown so that the main stem was not shaded. When plants were grown at different densities and the photosynthetic rates of leaves of a particular ontogenetic rank were measured, it was found that leaves on plants from higher densities had lower rates of photosynthesis. Also leaves on plants grown in bright light had higher photosynthetic rates than those on plants grown in dim light. It is concluded that the decline in the photosynthetic capacity of successive leaves in a rapidly growing simulated sward is due to the intense shading to which they are subjected during their expansion.     

Specific immunological response against the granulosis virus of the codling moth (Cydia pomonella) in woodmice (Apodemus sylvaticus): field observations

Antibodies specific to the granulosis virus (GV) of the codling moth (Cydia pomonella) were detected by indirect ELISA in sera of woodmice (Apodemus sylvaticus) trapped in an apple orchard sprayed by tractor-drawn mist blower with 2 × 10¹³ virus granules C. pomonella GV/ha. Such antibodies were absent from sera of mice trapped before virus had been applied. Virus antigens were detected by double antibody sandwich ELISA on the ground in and around the orchard and also in the faeces of woodmice inhabiting the orchard, but did not persist from one year to another. Some, but not all, of the samples containing virus antigens were found to be infective.