Search

第21回「社会・意識調査データベース(SORD）」ワークショップ, The 21st Workshop of Social and Opinion Research Database Project (SORD)

The ON and OFF channels are basic functional elements in parallel processing in the visual system in vertebrates including primates. We analysed the responses of the optic tract fibre activity in response to switching a flashlight on or off in 25 awake patients with Parkinson's disease who underwent stereotactic surgery targeting the internal globus pallidus. The responses were evoked in a darkened room by a light with a luminance of approximately 4 × 10(4) cd m(-2) at the eye and a wide-spectrum wavelength. Most of the responses at the light on event were excitatory (38 out of 41 sites, 93%). Thirty-five sites with increase in activity at the light on event showed reciprocal responses or no responses to light off, and these sites were classified as containing ON fibres. In single-fibre analysis, all of 14 ON fibres were recorded at the sites of multi-fibre excitatory responses. Six sites showed multi-fibre excitatory responses at the light off event; three sites showed sustained reduction in activity at the light on event, and these three sites were classified as containing OFF fibres. In single-fibre analysis, two OFF fibres were recorded at the sites of multi-fibre suppressive responses at the light on event, and the other two OFF fibres were recorded at the sites of multi-fibre excitatory responses at the light on event. We found that all excitatory responses to light on were transient, while all but one excitatory responses to light off were sustained. Reduction in activity tended to be smaller than increase in activity at the light on event. These results demonstrate that the ON and OFF channels, and their transient and sustained features function in visual processing in humans.

Seven types of tunic cells and multicellular vesicles are described in the tunic of the polyclinid ascidian Aplidium yamazii : spherical tunic cells (t. c. ), phagocytic t. c. , elongated t. c. , filopodial t. c. , micro-granular t. c. , morula-like t. c. , and macro-granular t. c. The spherical tunic cells are characterized by their spherical cell bodies filled with round granules. Some of these cells are located on the outside of the tunic, and they are probably released from the tunic. The phagocytic tunic cells are irregularly shaped and are motile. They contain phagosomes and vesicles laden with round granules, which are probably derived from the contents of the phagosomes. It is thought that the phagocytic tunic cells filled with the granules become the spherical tunic cells that are released from the tunic. The elongated tunic cells have thin cell bodies with long cellular processes extending from them. These processes appear to connect with each other and possibly form a contractile network in the tunic. The tunic vesicle is a hollow multicellular vesicle composed of thin flattened cells and cuboidal granular cells. The cuboidal cells of the tunic vesicle often contain a large amount of rough endoplasmic reticulum, indicating a high level of protein synthesis, and they may secrete some components of the tunic. The functions of the other tunic cells, i. e. , filopodial tunic cell, micro-granular tunic cell, morula-like tunic cell, and macro-granular tunic cell, are not clear.

The phagocytic activity of tunic cells of the colonial ascidian Aplidium yamazii was assessed by incubation of thin tunic slices including these cells with fluorescent microparticles. Only one type of tunic cell engulfed the microparticles. These phagocytic tunic cells are irregularly shaped, motile, and often contain phagosomes. Many of them also contain vesicles laden with round granules. Occasionally, they engulf another tunic cell. Because this type of tunic cell is always found in the tunic of histological sections prepared from whole (unsliced) colony specimens, these cells are probably distributed in the tunic under normal conditions. Peroxidase activity was demonstrated exclusively within granule-containing vesicles of some phagocytic tunic cells. This finding indicated that the phagocytic tunic cells might possess an oxygen-dependent microbicidal system. It is presumed that the phagocytic tunic cells migrate throughout the tunic matrix, engulf extraneous substances (including bacteria) and also function as scavengers to keep the tunic free of discarded tunic cells and other debris, such as from wounds.

We examined histological differences between the color patterns of two strains of the compound styelid ascidian Polyandrocarpa misakiensis. Two strains in this species show different color patterns. In the white-spot strain, each zooid has a large white spot on its dorsal side between the branchial and atrial siphons. In the spotless strain, each zooid has a fine white band, instead of the circular spot, between the siphons. Thin-layer chromatography on their pigments showed that there is no qualitative difference between the two strains. Observation of cryostat sections revealed that the differences between the color patterns of the two strains were mainly based on the distribution of red pigments in the epidermal layer. The area that lacks red pigments forms a circular white spot in the white-spot strain or a fine white band in the spotless strain on the dorsal side. In this area, white pigment cells (a type of blood cell), which are distributed in the mesenchymal space, can be seen through the epidermal layer.

Wild Botryllus schlosseri collected from a 5 × 5 m area in Mutsu Bay (Aomori Prefecture, Japan) were tested for alloresponses in intrapopulation colony allorecognition assays (CAAs). Results indicate that rejection patterns are similar to those recorded previously in the populations from Monterey and Santa Barbara, California, from the Mediterranean coast of Israel, and from the Venetian lagoon, Italy. The only difference was the marked accumulation of bright-yellow blood cells in the tips of interacting ampullae. Pairwise CAAs which were performed on all combinations (n = 91) from 14 colonies resulted in 12.1% fusions, which gives a populational estimation of 32 alleles on the fusibility locus. A fusibility chart for these 14 genotypes revealed 18-19 different, not equally frequent, allorecognition alleles, of which 12 were assigned to only one genotype, each; 5 occurred twice, and each one of 2 alleles was present in three different genotypes. It is concluded that the sampled area was too small to represent the probable higher number of fusibility alleles residing in this population.

Colony allorecognition assays (CAAs) were performed between colonies of the world-wide distributed tunicate Botryllus schlosseri, sampled from the Mediterranean coast of Israel (Is), from Monterey, California (Mon) and from Mutsu Bay, Japan (Ja). While all 48 Is vs Ja CAAs resulted in nonfusion responses, unexpectedly, 4.4% of the 45 Is vs Mon pairs and 12.0% of the 25 Ja vs Mon assays ended in colony fusions. Allogeneic effector mechanisms in all 3 populations were similar, except for the Ja population which was characterized additionally by the appearance of masses of bright yellow blood cells gathered in the tips of interacting ampullae. A total of 201 multiple CAAs on 24 Is vs Mon, 22 Is vs Ja and 21 Ja vs Mon rejecting pairs did not show an allospecific memory in the rejection phenomenon. Results are discussed in view of the accumulated data on allogeneic responses in 5 remote populations of B. schlosseri.

Fine structure of the ascidian tunic cuticle was studied by transmission and scanning electron microscopy in 26 species belonging to 10 families. In 11 species of 8 families, the cuticular surface is ornamented with numerous minute protrusions that are papillate in shape and usually up to 100 nm in height. The present results in addition to the previous ones [1] gave us more information about morphology of protrusions and their distribution in 51 species ranging over 13 families out of the 15 ones of ascidians. It reveals a general tendency that the protrusions occur in the limited families and related species have the protrusions of similar size. Thus, the protrusions proved to have some features of certain phylogenetic significance in many cases. Brief references were made to the taxonomic position of such problematic genera as Pterygascldia in the Cionidae and Sorbera in the Hexacrobylidae on the basis of the present study.