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241.
Effect of phenoxazine derivatives (actinomycin D, l,8-dimethyl-3-aminophenoxazone-2, 3-aminophenoxazone-2, sodium resazurate, gallocyanine, fluorescent blue and capri blue) on amino acid transport in rat small intestine was investigated using tissue accumulation method. Capri blue (CI–51015) inhibited the accumulation of l-leucine, l-alanine and l-valine, and scarcely inhibited that of D-glucose. Kinetic analysis showed that the inhibition of amino acid accumulation by this pigment was non-competitive. Actinomycin D had no effect on amino acids and d-glucose accumulation in vitro at the high and low concentrations of these substances. High concentration of actinomycin D and long period of incubation had no effect, too. Accumulation of amino acids into the intestinal tissue was not significantly decreased or increased by the presence of other phenoxazine derivatives. 相似文献
242.
Makoto Tajima Makio Morita Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):1277-1281
When 10?3m cysteine solution was irradiated in the presence of glucose at the concentration of ten-fold of cysteine, the G-values of products produced from cysteine were similar to those from 10?3m cysteine solution. On the other hand, the yield of carbonyl compound from glucose was suppressed completely by interaction between cysteine and radicals which are secondarily produced from glucose.Methionine could not suppress the yield of carbonyl compound from glucose, and, G-values of products from methionine varied in comparison with those from solution containing methionine only.From the results using scavenger, it was concluded that oxidation to methionine sulfoxide and cleavage to α-aminobutyric acid was caused by OH and attack, respectively. 相似文献
243.
244.
Yukio Katori Tomonori Takasaka Makoto Ishikawa Akira Tonosaki 《Cell and tissue research》1994,276(2):245-252
The surface coat, ciliary process, and microvilli of the lamprey neuromast were examined with electron microscopy after tannic acid prefixation and lectin histochemistry. The neuromast was found to exist in the form of a dermal mound with a furrow in the middle. On the bottom of the furrow, the hair cell was characterized by a kinocilium and 15–20 stereocilia, arranged along the longitudinal axis of the furrow. Spanning structures were demonstrated between the kinocilium and stereocilia as well as between stereocilia. The surface coat, enhanced by tannic acid prefixation, was particularly rich over the surface of the supporting cell; by contrast, it was thin over the hair cell. Some lectins (PNA, GS-I, SBA, WGA) showed affinity to the surface coat of the supporting cell as well as the hair cell, and the others (RCA-I, MPA, ConA) showed affinity only to the supporting cell. These differences in the structure and affinities of the surface coat suggest an extracellular milieu highly specialized for the hair cell in this particular form of the mechanoreceptor. 相似文献
245.
Coevolution of the S-locus genes SRK,SLG and SP11/SCR in Brassica oleracea and B. rapa 总被引:1,自引:0,他引:1
Sato K Nishio T Kimura R Kusaba M Suzuki T Hatakeyama K Ockendon DJ Satta Y 《Genetics》2002,162(2):931-940
Brassica self-incompatibility (SI) is controlled by SLG and SRK expressed in the stigma and by SP11/SCR expressed in the anther. We determined the sequences of the S domains of 36 SRK alleles, 13 SLG alleles, and 14 SP11 alleles from Brassica oleracea and B. rapa. We found three S haplotypes lacking SLG genes in B. rapa, confirming that SLG is not essential for the SI recognition system. Together with reported sequences, the nucleotide diversities per synonymous and nonsynonymous site (pi(S) and pi(N)) at the SRK, SLG, and SP11 loci within B. oleracea were computed. The ratios of pi(N):pi(S) for SP11 and the hypervariable region of SRK were significantly >1, suggesting operation of diversifying selection to maintain the diversity of these regions. In the phylogenetic trees of 12 SP11 sequences and their linked SRK alleles, the tree topology was not significantly different between SP11 and SRK, suggesting a tight linkage of male and female SI determinants during the evolutionary course of these haplotypes. Genetic exchanges between SLG and SRK seem to be frequent; three such recent exchanges were detected. The evolution of S haplotypes and the effect of gene conversion on self-incompatibility are discussed. 相似文献
246.
Nobuyuki Kimura Makoto Inoue Sachi Okabayashi Fumiko Ono Takayuki Negishi 《The Journal of biological chemistry》2009,284(45):31291-31302
Growing evidence suggests that endocytic dysfunction is intimately involved in early stage Alzheimer disease pathology, such as the accumulation of β-amyloid precursor protein in enlarged early endosomes. However, it remains unclear how endocytic dysfunction is induced in an age-dependent manner. Cytoplasmic dynein, a microtubule-based motor protein, interacts with another microtubule-associated protein, dynactin. The resulting dynein-dynactin complex mediates minus end-directed vesicle transport, including endosome trafficking. We have previously shown that the interaction between dynein-dynactin complexes is clearly attenuated in aged monkey brains, suggesting that dynein-mediated transport dysfunction exists in aged brains. Our immunohistochemical analyses revealed that age-dependent endocytic pathology was accompanied by an increase in Rab GTPases in aged monkey brains. Here, we demonstrated that siRNA-induced dynein dysfunction reproduced the endocytic pathology accompanied by increased Rab GTPases seen in aged monkey brains and significantly disrupted exosome release. Moreover, it also resulted in endosomal β-amyloid precursor protein accumulation characterized by increased β-site cleavage. These findings suggest that dynein dysfunction may underlie age-dependent endocytic dysfunction via the up-regulation of Rab GTPases. In addition, this vicious circle may worsen endocytic dysfunction, ultimately leading to Alzheimer disease pathology. 相似文献
247.
Koizumi J Kojima T Kamekura R Kurose M Harimaya A Murata M Osanai M Chiba H Himi T Sawada N 《The Journal of membrane biology》2007,218(1-3):1-7
The epithelium of upper respiratory tissues such as nasal mucosa forms a continuous barrier to a wide variety of exogenous
antigens. The epithelial barrier function is regulated in large part by the intercellular junctions, referred to as gap and
tight junctions. However, changes of gap and tight junctions during differentiation of human nasal epithelial (HNE) cells
are still unclear. In the present study, to investigate changes of gap and tight junctions during differentiation of HNE cells
in vitro, we used primary human HNE cells cocultured with primary human nasal fibroblast (HNF) cells in a noncontact system. In HNE
cells cocultured with HNF cells for 2 weeks, numerous elongated cilia-like structures were observed compared to those without
HNF cells. In the coculture, downregulation of Cx26 and upregulation of Cx30.3 and Cx31 were observed together with extensive
gap junctional intercellular communication. Furthermore, expression of the tight junction proteins claudin-1, claudin-4, occludin
and ZO-2 was increased. These results suggest that switching in expression of connexins and induction of tight junction proteins
may be closely associated with differentiation of HNE cells in
vitro and that differentiation of HNE cells requires unknown soluble factors secreted from HNF cells. 相似文献
248.
Murayama K Shirouzu M Kawasaki Y Kato-Murayama M Hanawa-Suetsugu K Sakamoto A Katsura Y Suenaga A Toyama M Terada T Taiji M Akiyama T Yokoyama S 《The Journal of biological chemistry》2007,282(7):4238-4242
The Rac-specific guanine nucleotide exchange factor (GEF) Asef is activated by binding to the tumor suppressor adenomatous polyposis coli mutant, which is found in sporadic and familial colorectal tumors. This activated Asef is involved in the migration of colorectal tumor cells. The GEFs for Rho family GTPases contain the Dbl homology (DH) domain and the pleckstrin homology (PH) domain. When Asef is in the resting state, the GEF activity of the DH-PH module is intramolecularly inhibited by an unidentified mechanism. Asef has a Src homology 3 (SH3) domain in addition to the DH-PH module. In the present study, the three-dimensional structure of Asef was solved in its autoinhibited state. The crystal structure revealed that the SH3 domain binds intramolecularly to the DH domain, thus blocking the Rac-binding site. Furthermore, the RT-loop and the C-terminal region of the SH3 domain interact with the DH domain in a manner completely different from those for the canonical binding to a polyproline-peptide motif. These results demonstrate that the blocking of the Rac-binding site by the SH3 domain is essential for Asef autoinhibition. This may be a common mechanism in other proteins that possess an SH3 domain adjacent to a DH-PH module. 相似文献
249.
250.
Furaquinocin is a natural polyketide-isoprenoid hybrid (meroterpenoid) produced by Streptomyces sp. strain KO-3988. All of the fur genes required for furaquinocin biosynthesis have been cloned, and the heterologous production of furaquinocin has been demonstrated in Streptomyces albus. Here, we report the identification of 8-amino-2,5,7-trihydroxynaphthalene-1,4-dione (8-amino-flaviolin) produced by the S. albus heterologous expression of the three contiguous genes encoding type III polyketide synthase (Fur1), monooxygenase (Fur2), and aminotransferase (Fur3) in the furaquinocin biosynthetic gene cluster. An S. albus transformant (S. albus/pWHM-Fur2_del3) harboring the fur gene cluster and lacking the fur3 gene did not produce furaquinocin, whereas furaquinocin production was restored when 8-amino-flaviolin was added to the culture medium of S. albus/pWHM-Fur2_del3. These results demonstrate that Fur3 aminotransferase is essential for furaquinocin biosynthesis and that 8-amino-flaviolin is an early-stage intermediate in furaquinocin biosynthesis. We propose that the biosynthetic pathway generating 8-amino-flaviolin is the common route for the biosynthesis of Streptomyces meroterpenoids. 相似文献