Gap Junctions Mediate Glucose Transport Between GLUT1-Positive and -Negative Cells in the Spiral Limbus of the Rat Cochlea

To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus.     

Heterogeneity and tissue-specific expression of eukaryotic transcription factor S-II-related protein mRNA

Two new cDNA clones for S-II-related proteins were isolated from a mouse liver cDNA library. Analyses of these clones suggested that S-II proteins are a family of proteins with relatively conserved C-terminal regions but variable N-terminal regions, and that some members of this family are expressed in a tissue-specific manner.     

Purification of sarcotoxin III, a new antibacterial protein of Sarcophaga peregrina

A glycine-rich antibacterial protein with a molecular mass of 7,000 termed sarcotoxin III, was purified to homogeneity from the hemolymph of third instar larvae of Sarcophaga peregrina. When the hemolymph was fractionated, this protein was recovered in the same fraction as sarcotoxin I, a group of potent antibacterial proteins that have been purified. But, it was clearly different from sarcotoxin I in amino acid composition and molecular mass. Sarcotoxin III was shown to be induced in the hemolymph in response to injury of the larval body wall.     

Purification of Sarcophaga (fleshfly) lectin and detection of sarcotoxins in the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina.

An established cell line originating from a Sarcophaga peregrina (fleshfly) embryo, NIH-Sape-4, was found to synthesize mRNAs for Sarcophaga lectin and sarcotoxin IA, but not those for storage protein or 25 kDa protein. These four proteins are known to be synthesized in the fat-body of third-instar larvae, and the two former in particular are known to participate in the defence mechanism of this insect and to be induced in response to injury of the body wall. Thus the embryonic cell line NIH-Sape-4 synthesizes certain defence proteins constitutively. This cell line will be useful for large-scale purification of Sarcophaga lectin, since 50 micrograms of purified Sarcophaga lectin could be obtained from about 400 ml of culture medium.     

Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes II. Chromosomal aberration tests with cultured mammalian cells

The chromosomal aberration test using a Chinese hamster lung cell line (CHL) was carried out on ptaquiloside and its related compounds, hypoloside B, hypoloside C, illudin M and illudin S. Ptaquiloside induced chromosomal aberrations at doses as low as 4.5 μg/ml (0.0113 mM). The clastogenic effect was ph-dependent. The same activity was observed at a 90-fold higher dose at pH 5.3 in the culture medium compared with the activity at pH 74. or pH 8.0. Both hypoloside B and hypoloside C were also clastogenic at almost the same dose levels as that of ptaquiloside. Illudin M and illudin S were also potet clastogens and induced aberrations at much lower doses than ptaquiloside. These results suggest that the clastogenic effect is involved in the mechanism of carcinogenic potency of ptaquiloside in animals.     

Evolutionary trends of the hairy-faceSaguinus in terms of the dental and cranial morphology

Shape variations in the dentition and the cranium were analyzed for sevenSaguinus forms of the hairy-face tamarin by applying the factor analysis method. The results obtained for the dental and cranial measurements were almost consistent with each other. The magnitude of the difference in shape factors between theS. nigricollis group and theS. midas group is appreciably larger than that between the former group and theS. mystax group. If the ancestral geographic centre of origin is postulated as being within the region which is inhabited by the livingS. nigricollis group, the morphological distances between any pairs of groups correlate well with the geographic distances between them. Concerning the dental and cranial morphologies, the physical changes in the three species group probably took place in two directions; that is, from theS. nigricollis group to theS. mystax group, and from theS. nigricollis group to theS. midas group. The forms belonging to each species group are more closely related to each other, with the exception ofS. imperator in theS. mystax group. The uniqueness ofS. imperator was clearly demonstrated by factor analysis and distance analysis. In theS. mystax group, although still hypothetical,S. imperator may have been related only through the basic ancestral stock toS. labiatus andS. mystax.     

Comparison of growth properties of carrot hairy root in various bioreactors

Summary Growth properties of carrot hairy root cells in various bioreactors were investigated. A turbine-blade reactor and an immobilized rotating drum reactor were found to be advantageous for the hairy root culture because of a high oxygen transfer coefficient (k in L a). After 30 days of culture, 10 g/l of dry hairy root cells were obtained in both bioreactors and maximum growth rates (V _m ) were found to be 0.63 and 0.61 g/l per day for the turbine-blade reactor and immobilized rotating drum reactor, respectively. Specific growth rates () at various cultivation times were observed to be linearly proportional to X/k _l a for both bioreactor configurations where X is the cell concentration. The estimated specific oxygen uptake rate of 0.34 mmol O₂/g dry cells per hour compares fairly well with an experimental value of 0.3.     

Effect of GRF and somatostatin on 7B2 secretion by rat GH1 cells

A novel pituitary protein "7B2" was secreted by GH1 cells. The secretion of 7B2 was increased in the presence of human GRF in a dose-responsive manner. In contrast, a somatostatin analog, SMS 201-995, revealed the inhibitory effects on the basal- and GRF-induced secretion of 7B2 at the concentration of 10(-7) M. These findings suggest that 7B2 is a secretory protein of rat GH1 cells under certain conditions.     

Nuclear GTP-binding proteins of Swiss 3T3 cells

The GTP-binding proteins of Swiss 3T3 cell nuclei were analyzed by filter binding assay and UV cross-linking analysis. The results showed the presence of multiple GTP-binding proteins in the nuclei. Scatchard analysis revealed that the Kd value for GTP binding to high-affinity components was 69 nM, that to low-affinity components being 2.7 microM. The GTP-binding activities of some nuclear proteins were found to change significantly in response to the growth conditions of the cells. During culture of cells in medium without serum, the GTP-binding activity of a 140 kDa protein clearly decreased, whereas that of a 40 kDa protein increased.