Mouth Movements Diminish Taste Adaptation, but Rate of Mouth Movement does not Affect Adaptation

The degree of adaptation to five concentrations of sucrose wasmeasured. Solutions were kept in the mouth for 25 s; a sweetnessjudgement was given every 5 s. There were four conditions ofmouth movements: no movement, slow, medium and fast mouth movements.It was found that when mouth movements are made there is lessadaptation than when there is no mouth movement; however, therate of movement does not appear to influence the degree ofadaptation. Furthermore concentration was found to have an effect.In the no-movement condition, the degree of adaptation seemsto rise with concentration, whereas in the movement conditionsthe opposite effect occurs, i.e. a decrease in the degree ofadaptation occurs with increasing sucrose concentration. Thesephenomena might be explained by the stimulated tongue area,or by taste constancy. Chem. Senses 21: 545–551, 1996.     

A Method for Isolating and Preparing Silica Bodies in Grasses for Scanning Electron Microscopy

Silica bodies are discrete deposits of dehydrated silica within epidermal cells. To describe these bodies completely, surrounding organic and unsilicified material must be removed. Methods generally used for isolating and preparing silica bodies were unsuitable for most grass species. An effective method for studying grasses is described here. After ashing the plant tissue, the ash was repeatedly rinsed with HCl in a specialized multiple funnel manifold and collected on Nuclepore filters. In addition, the silica bodies were sonicated for a few minutes to remove any remaining mineral impurities. Compared to conventional procedures, this method has a number of advantages: unsilicified material and mineral impurities were removed effectively, smaller quantities of plant tissue could be used, and the loss of silica bodies was minimized.     

Incorporation of tritiated thymidine in germinal and somatic cells of the onion fly, Hylemya antiqua (Diptera: Anthomyiidae), as determined by autoradiography

Incorporation of³H-thymidine both in germinal and somatic cell types in young male adults of the onion fly,Hylemya antiqua (Meigen) reveals among other things the temporal pattern of spermatogenesis. Labeling of cells in the female reproductive organs is also described. Nuclei of fat cells, midgut epithelium, accessory glands and muscles, and occasionally hemocytes also show labeling. In oenocytes and the Malpighian tubules tritiated thymidine is incorporated in the cytoplasm.     

Effects of temperature on egg-chamber development in the onion fly, Hylemya antiqua (Diptera: Anthomyidae)

Young onion flies were placed in cages at four temperatures, 15°, 18°, 21° and 24°. Every 2 days the development of the egg chambers in the ovarioles, mating, egg production and mortality were scored. Influence of the temperature on the speed of egg-chamber development was very distinct. There was a high positive correlation between the development of the first and the second egg chamber. At 24° a significant difference in speed of egg-chamber development was found at two low levels of light intensity.

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Résumé L'influence de la température sur la maturation des follicules de la mouche de l'oignon, Hylemya antiqua Meigen, a été analysée.Des jeunes adultes ont été mis en 4 cages et soumis au régime des températures suivantes: 15°, 18°, 21° et 24°. La maturation des follicules de huit femelles a été vérifiée pour chaque température et après 2 jours, par examen des ovaires sur le vivant. L'activité d'accouplement a été également contrôlée, ainsi que la ponte et la mortalité.L'effet de la température sur la vitesse dé développement des follicules est très net. À 15° le premier follicule n'a pas encore atteint la maturité après 26 jours. Par contre aux températures plus élevées la maturation se déroule plus vite. Le développement du deuxième follicule est en corrélation positive avec celui du premier (r=0.866).À 24°, deux niveaux relativement bas de l'intensité de la lumière causent des différences dans la vitesse de développement des premiers follicules.

     

The Effect of Sweeteners on Perceived Viscosity

Two different sweeteners, sucrose and aspartame, were matchedin perceived sweetness intensity. These solutions were thickenedwith carboxymethylcellulose to six different viscosity levels.Sucrose and aspartame appeared to decrease perceived viscosityof the solutions at a specific sweetener concentration, at allviscosity levels. However, in a second similar experiment withthree viscosity levels and seven sucrose concentrations no effectof sucrose concentration on perceived viscosity was found. Reasonsfor these conflicting results are discussed. No definite conclusionsabout the effect of sweeteners on perceived viscosity can asyet be drawn. Chem. Senses 20: 441–450, 1995.