Gene expression pattern analysis of the tight junction protein, Claudin, in the early morphogenesis of Xenopus embryos

To study how epithelial layers are formed during early development in Xenopus embryos, we have focused on Claudin, the major component of the tight junction. So far, 19 claudin genes have been found in the mouse, expressed in different epithelial tissues. However, though a number of cytological studies have been done for the roles of Claudins, their expression patterns and functions during early embryogenesis are largely unknown. We found three novel Xenopus claudin genes, which are referred to as claudin-4L1, -4L2, and -7L1. At the early gastrula stage, claudin-4L1, -4L2, and -7L1 mRNAs were detected in the ectoderm and in the mesoderm. At the late gastrula stage, claudin mRNAs were detected in the ectoderm through the involuting archenteron roof. At the neurula stage, claudin-4L1/4L2 and -7L1 mRNAs were differentially expressed in the neural groove and the epidermal ectoderm. At the tailbud stage, the claudin mRNAs were found in the branchial arches, the otic vesicles, the sensorial layer of the epidermis, and along the dorsal midline of the neural tube. In addition, claudin-4L1/4L2 mRNAs were detected in the pronephros and the endoderm, whereas claudin-7L1 mRNA was observed in the epithelial layer of the epidermis.     

Effects of Cys mutation on taurocholic acid transport by mouse ileal and hepatic sodium-dependent bile acid transporters

All cysteines of mouse ileal and hepatic sodium-dependent bile acid transporters (Isbt and Ntcp, respectively) were individually replaced by alanine. Replacement of Cys106 in Isbt and Cys96 in Ntcp, which are located closely in alignment, decreased taurocholate uptake. Although Cys51 in Isbt is conserved in Ntcp, the replacement spoiled Isbt only. Both similarity and difference in the arrangement of functional sites are suggested.     

Effects of stereochemistry of sugars on protein stabilities

We investigated thermal stabilities of four proteins in the presence of four kinds of sugars to analyze the mechanism of stabilization of proteins by additives. These proteins were stabilized by the addition of sugars, and the degree of stabilization correlated to the partial molar isentropic compressibility of the sugar.     

Convenient synthesis and evaluation of enzyme inhibitory activity of several N-alkyl-, N-phenylalkyl,and cyclic isourea derivatives of 5a-carba-alpha-DL-fucopyranosylamine

Convenient synthesis and chemical modification of the potent alpha-L-fucosidase inhibitor, 5a-carba-alpha-DL-fucopyranosylamine (1), are described. Among seven N-substituted and three cyclic isourea derivatives newly prepared, the N-octyl derivative was found to be the strongest inhibitor of alpha-L-fucosidase (bovine kidney) more potent (K(i)=0.016 microM) than deoxyfuconojirimycin (K(i)=0.031 microM) with p-nitrophenyl-alpha-L-fucopyranoside as the substrate.     

Morphological studies on the bathyal ascidian,Megalodicopia hians Oka 1918 (Octacnemidae,Phlebobranchia), with remarks on feeding and tunic morphology

Megalodicopia hians Oka is a solitary ascidian belonging to the family Octacnemidae inhabiting the bathyal /abyssal zone as well as other octacnemid ascidians. The phylogenetic relationship of octacnemids is open to argument because of its extraordinary morphological features due to habitat adaptation, e.g., a pharynx lacking ciliated stigmata. Aggregations of M. hians were discovered by the manned submersible Shinkai 2000 in the bathyal seafloor of Toyama Bay, Japan Sea, in 2000; this was the first in situ observation of M. hians in the Japanese coastal waters. In 2001, a total of 36 M. hians specimens were collected from the bay (592 to approximately 978 m deep). In situ observation indicated that M. hians usually opens its large oral apertures to engulf the drifting food particles in the water current. Microscopical observation of the gut contents also showed that M. hians is a non selective macrophagous feeding on small crustaceans, diatoms, detritus, and so on. Along with the position of the intestinal loop and gonad, the morphological characteristics of the tunic (integument of ascidians) suggest that M. hians is closely related to Cionidae and/or Corellidae. Some symbiotic/parasitic organisms were occasionally found in the tunic, including rod-shaped bacteria, fungi-like multicellular structure, and spawns of unknown animals.     

Molecular cloning of Chinese hamster ceramide glucosyltransferase and its enhanced expression in peroxisome-defective mutant Z65 cells

To clarify the metabolic bases of characteristic increases in the concentrations of glucosylceramide (CMH) and GM3 in peroxisome-defective mutant Chinese hamster ovary (CHO) cells (Z65), we measured the ceramide glucosyltransferase (CGT) and beta-glucosidase activities in Z65 and CHO-K1 cells, and found that the former enzyme was responsible for the accumulation of CMH in Z65 cells. Inhibition of CGT by D,L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) caused a marked reduction in a incorporation of [3-14C]serine to CMH in both CHO-K1 and Z65 cells, but resulted in the accumulation of ceramide in Z65 cells in a concentration higher than that in CHO-K1 cells. Then, we cloned the cDNA encoding CGT from CHO-K1 cells, which exhibited sequence homology with the human gene product (98.7%). Northern blot analysis of CGT revealed increased expression of it in Z65 cells compared with that in CHO-K1 cells, which probably caused the simultaneous increase in GM3. With an immunohistochemical procedure, GM3 was found to be more strongly expressed in the cell membrane of Z65 cells than in CHO-K1 cells.     

Time allocation to subsistence activities among the Huli in rural and urban Papua New Guinea

Time spent on subsistence activities was compared between rural sedentes and urban migrants of the Huli population in Papua New Guinea. Person-day observation data were collected for rural sedentes (441) in the Tari basin and for urban migrants in Port Moresby (175). The time spent on subsistence activities by males was longer in the urban area than in rural areas, while that by females was similar in both areas. Conspicuous gender inequality with respect to labour hours in rural areas seems to diminish when people move to urban areas, reflecting the different subsistence regime between rural and urban environments.     

Thelephantins D-H: five p-terphenyl derivatives from the inedible mushroom Thelephora aurantiotincta

Five p-terphenyl derivatives named thelephantins D-H (1-5) together with nine known compounds, thelephantins A-C (6-8), ganbajunin E (9), p-hydroxylbenzoic acid (10), ganbajunin C (11), thelephorin A (12), 2-O-methylatromentin (13) and atromentin (14), were isolated from the methanolic extract of fruit bodies of the Thelephoraceous Basidiomycete Thelephora aurantiotincta. Their structures were elucidated by high-resolution MS, 2D NMR, IR and UV spectroscopic analysis.     

Rapid increase of vacuolar volume in response to salt stress

Suspension-cultured cells of mangrove [Bruguiera sexangula (Lour.) Poir.] showed a rapid increase in vacuolar volume under salt stress, although there was no change in the cell volume. The rapid increase in the vacuolar volume was an active process, which followed the activation of the tonoplast H(+)-ATPase and the vacuolar acid phosphatase. The same phenomenon was observed in barley (Hordeum vulgare L. cv. Doriru) root meristematic cells under salt stress but not in pea ( Pisum sativum L.). Increases in vacuolar volume could potentially protect the cytoplasm by decreasing the cytoplasmic volume during the initial phases of salt stress.