SENSORY INTERACTIONS IN MIXTURES

Psychological studies have assessed the intensity of simple sensory mixtures, both in taste and olfaction. In taste mixtures, suppression or partial masking among the components is often observed. An analogous result is often found in odor mixtures, counteraction of one component in the presence of a second odor. These effects, particularly taste suppression, are also observed in food systems. Interactions between sensory modalities are far more complex, ranging from inhibition of taste and odor sensations by trigeminal irritation, to relative independence of tastes from odor stimulation and independence of odors from tastes.     

Flexible nacre in the nautiloid Isorthoceras, with remarks on the evolution of cephalopod nacre

Secondarily phosphatized shells of Isorthoceras sociale (Hall) from the Upper Ordovician Maquokcta shale, Iowa, U.S.A., often have their original ultrastructurc preserved. Scanning Electron Microscope study reveals that the nacreous layer is similar to that in the shells of Recent Nautilus , except that the nacreous tablets usually have a much larger diameter, and that numerous vertical interspaces arc left between adjacent stacks of tablets. Because of the latter condition, the nacre in A sociale is porous, whereas it is compact in Nautilus. The pores in the nacre were probably filled with a non-mincralizcd organic matrix. The high porosity and high content of organic matrix made the nacreous layer of I. sociale much more flexible and considerably less strong than that in Nautilus. As a consequence, the shells of I. sociale , and probably also of other orthoconic cephalopods, were more flexible and could not withstand such high hydrostatic pressures as the shells of Nautilus. During evolution, the porosity of the nacreous layer became completely reduced. As a result, the mechanical properties of the nacre changed towards a lower flexibility and a higher tensile strength. Cephalopoda, Nautiloidea, nacre, ultrastructurc, phosphatization, Upper Ordovician.     

Identification of an Apically-Located Antigen That Is Conserved in Sporozoan Parasites

ABSTRACT. Sporozoan parasites of the phylum Apicomplexa all possess common apical structures. The current study used a monoclonal antibody (mAb-E12) to identify a conserved antigen in the apical region of merozoites of seven species of Plasmodium (including rodent, primate and human pathogens), tachyzoites of Toxoplasma gondii , bradyzoites of Sarcocystis bovis , and sporozoites and merozoites of Eimeria tenella and E. acervulina. The antigen was also present in sporozoites of haemosporinid parasites. Immunofluorescence studies showed that the antigen was restricted to the apical 3rd of these invasive stages. Using immunoelectron microscopy, labeling was demonstrated in the region of the polar ring, below the paired inner membranes of the parasite pellicle, and near the subpellicular microtubules radiating from the polar ring of merozoites and sporozoites of E. tenella . The majority of the antigen could be extracted with 1% Triton-X 100, but a portion remained associated with the cytoskeletal elements. The molecule has a relative rate of migration (M_r) of 47,000 in Plasmodium spp. and 43–46,000 in coccidian species. Since the epitope recognized by mAb-El 2 is highly conserved, restricted to motile stages, and appears to be associated with microtubules, this antigen could be involved in cellular motility and cellular invasion.     

EFFECTS OF FLOW RATE ON TASTE INTENSITY RATINGS

The effects of stimulus flow rate on perceived taste intensitywere studied in man using five concentrations of each of fourstimulus compounds (sodium chloride, hydrochloric acid, quininehydrochloride, and sucrose) and six different flow rates from1.2 to 12.0 cc/sec. AH stimuli were presented through a tonguechamber. Perceived taste intensity increased monotonically withflow rate for every stimulus condition tested. Psychophysicalfunctions calculated across flow rates (rather than across physicalconcentrations) support the view that flow rates mimic physicalconcentration.     

Redescription of Rhodopsis pusih Bush, a little known but widely distributed species of Serpullidae (Polychaeta)

Rhodopsis pusilla Bush 1905. a minute species characterized by a chitinous opereular plate bearing numerous spines is redescribed and a neotype is designated. Apomatolos Uchida. 1978 is synonymized with Rhodopsis . Ventral fillform mouth-palps are present a rarely observed character in common with Pseudovermilia Bush. Variability between and within populations from different seas is discussed. Rhodopsis pusilla from Heron Island shows opercular dimorphism. Pouch-like brood chambers similar in texture (SEM) to the Rhodopsis tubes and integrally associated with rings marking successive position of the peristome were found on some tubes. These brood chambers. presumed to belong to Rhodopsis are described with conjectures as to their mode of formation. Some aspects of opercular polymorphism in serpulids are discussed.     

Isolation and characterization of microsatellite markers in Labiotermes labralis (Isoptera,Termitidae, Nasutitermitinae)

We report here on the development of six polymorphic microsatellite loci for Labiotermes labralis. This soil‐feeding species is restricted to the Neotropical rainforest and then could represent a major candidate for being a bio‐indicator of anthropic disturbance resulting in the forest fragmentation. The microsatellite loci were isolated and characterized using a microsatellite‐enriched genomic library. The primers were tested on a French Guyanese population of L. labralis, represented by the sampling of one soldier in 22 nests. The primers were also tested against nine species of the same Nasutitermitinae subfamily and were successfully amplified at five loci in Armitermes minutus.