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121.
122.
Anuran (frog) tadpoles and urodeles (newts and salamanders) are the only vertebrates capable of fully regenerating amputated limbs. During the early stages of regeneration these amphibians form a "blastema", a group of mesenchymal progenitor cells that specifically directs the regrowth of the limb. We report that wnt-3a is expressed in the apical epithelium of regenerating Xenopus laevis limb buds, at the appropriate time and place to play a role during blastema formation. To test whether Wnt/beta-catenin signaling is required for limb regeneration, we created transgenic X. laevis tadpoles that express Dickkopf-1 (Dkk1), a specific inhibitor of Wnt/beta-catenin signaling, under the control of a heat-shock promoter. Heat-shock immediately before limb amputation or during early blastema formation blocked limb regeneration but did not affect the development of contralateral, un-amputated limb buds. When the transgenic tadpoles were heat-shocked following the formation of a blastema, however, they retained the ability to regenerate partial hindlimb structures. Furthermore, heat-shock induced Dkk1 blocked fgf-8 but not fgf-10 expression in the blastema. We conclude that Wnt/beta-catenin signaling has an essential role during the early stages of limb regeneration, but is not absolutely required after blastema formation. 相似文献
123.
In the present study, we examined the effects of four kinds of cysteine protease inhibitors (E64, E64d, leupeptin, and ALLN) on the in vitro asexual growth of Babesia bovis. Of these, only the lipophilic inhibitors, E64d and ALLN, were found to effectively inhibit the growth of B. bovis. In further experiments, E64d, but not ALLN, significantly suppressed the parasite’s invasion of host erythrocytes, while both chemicals, especially ALLN, inhibited the parasite’s replication within the infected erythrocytes. These data suggested the presence of cysteine protease(s) derived from B. bovis, in which the protease(s) would play important roles in the erythrocyte invasion and/or replication processes of the parasite. 相似文献
124.
Fujii T Yokoyama T Ninagi O Kakehashi K Obara Y Nenoi M Ishikawa T Mita K Shimada T Abe H 《Genetica》2007,130(3):267-280
In deletion-mapping of W-specific RAPD (W-RAPD) markers and putative female determinant gene (Fem), we used X-ray irradiation to break the translocation-carrying W chromosome (W
Ze
). We succeeded in obtaining a fragment of the W
Ze
chromosome designated as Ze
W, having 3 of 12 W-RAPD markers (W-Bonsai, W-Yukemuri-S, W-Yukemuri-L). Inheritance of the Ze
W fragment by males indicates that it does not include the Fem gene. On the basis of these results, we determined the relative positions of W-Yukemuri-S and W-Yukemuri-L, and we narrowed
down the region where Fem gene is located. In addition to the Ze
W fragment, the Z chromosome was also broken into a large fragment (Z1) having the +
sch
(1-21.5) and a small fragment (Z2) having the +
od
(1-49.6). Moreover, a new chromosomal fragment (Ze
WZ2) was generated by a fusion event between the Ze
W and the Z2 fragments. We analyzed the genetic behavior of the Z1 fragment and the Ze
WZ2 fragment during male (Z/Z1
Ze
WZ2) and female (Z1
Ze
WZ2/W) meiosis using phenotypic markers. It was observed that the Z1 fragment and the Z or the W chromosomes separate without fail. On the other hand, non-disjunction between the Ze
WZ2 fragment and the Z chromosome and also between the Ze
WZ2 fragment and the W chromosome occurred. Furthermore, the females (2A: Z/Ze
WZ2/W) and males (2A: Z/Z1) resulting from non-disjunction between the Ze
WZ2 fragment and the W chromosome had phenotypic defects: namely, females exhibited abnormal oogenesis and males were flapless
due to abnormal indirect flight muscle structure. These results suggest that Z2 region of the Z chromosome contains dose-sensitive gene(s), which are involved in oogenesis and indirect flight muscle development. 相似文献
125.
Prion infection correlates with hypersensitivity of P2X7 nucleotide receptor in a mouse microglial cell line 总被引:1,自引:0,他引:1
Takenouchi T Iwamaru Y Imamura M Kato N Sugama S Fujita M Hashimoto M Sato M Okada H Yokoyama T Mohri S Kitani H 《FEBS letters》2007,581(16):3019-3026
We recently established mouse microglial cells persistently infected with mouse-adapted scrapie ME7 (ScMG20/ME7) for in vitro study of prion pathogenesis. Here, we found that ScMG20/ME7 cells were hypersensitive to P2X7 receptor agonists, as demonstrated by sustained Ca(2+) influx, membrane pore formation, cell death, and interleukin-1beta release. P2X7 mRNA expression was upregulated in these cells, and also in scrapie-infected mice brains. Treatment with pentosan polysulfate eliminated the infectivity and disease-related forms of prion protein from ScMG20/ME7 cell cultures, however, hypersensitivity of P2X7 receptors remained. These results suggest that prion infections may strongly affect the P2X7 receptor system in mouse microglial cells. 相似文献
126.
Takano Y Yamauchi K Hayakawa K Hiramatsu N Kasai A Okamura M Yokouchi M Shitamura A Yao J Kitamura M 《FEBS letters》2007,581(3):421-426
Expression of nephrin, a crucial component of the glomerular slit diaphragm, is downregulated in patients with proteinuric glomerular diseases. Using conditionally immortalized reporter podocytes, we found that bystander macrophages as well as macrophage-derived cytokines IL-1beta and TNF-alpha markedly suppressed activity of the nephrin gene promoter in podocytes. The cytokine-initiated repression was reversible, observed on both basal and inducible expression, independent of Wilms' tumor suppressor WT1, and caused in part via activation of the phosphatidylinositol-3-kinase/Akt pathway. These results indicated a novel mechanism by which activated macrophages participate in the induction of proteinuria in glomerular diseases. 相似文献
127.
Rapid, transient induction of ER stress in the liver and kidney after acute exposure to heavy metal: evidence from transgenic sensor mice 总被引:2,自引:0,他引:2
Hiramatsu N Kasai A Du S Takeda M Hayakawa K Okamura M Yao J Kitamura M 《FEBS letters》2007,581(10):2055-2059
Endoplasmic reticulum (ER) stress-responsive alkaline phosphatase (ES-TRAP) serves as a sensitive indicator for ER stress. In response to heavy metals including cadmium, nickel and cobalt, hepatocytes and renal tubular cells expressing ES-TRAP exhibited ER stress and decreased ES-TRAP activity. In ES-TRAP transgenic mice, acute exposure to cadmium showed rapid, transient decreases in the activity of serum ES-TRAP. It was inversely correlated with the induction of endogenous ER stress markers in the liver and kidney. Our result provides first evidence for the acute, reversible induction of ER stress in vivo after exposure to heavy metal. 相似文献
128.
The tiger pufferfish (fugu), Takifugu rubripes, is a model fish that has had its genome entirely sequenced. By performing genomewide linkage analyses, we show that the sex of fugu is determined by a single chromosomal region on linkage group 19 in an XX-XY system. 相似文献
129.
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
130.
Miyagi M Yokoyama H Hibi T 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,854(1-2):286-290
An HPLC protocol for sugar microanalysis based on the formation of ultraviolet-absorbing benzoyl chloride derivatives was improved. Here, samples were prepared with a C-8 cartridge and analyzed with a high efficiency ODS column, in which porous spherical silica particles 3 microm in diameter were packed. These devices allowed us to simultaneously quantify multiple sugars and sugar alcohols up to 10 ng/ml and to provide satisfactory separations of some sugars, such as fructose and myo-inositol and sorbitol and mannitol. This protocol, which does not require special apparatuses, should become a powerful tool in sugar research. 相似文献