Effect of cysteine desulfhydrase gene disruption on L-cysteine overproduction in Escherichia coli

In Escherichia coli, the enzyme called cysteine desulfhydrase (CD), which is responsible for L-cysteine degradation, was investigated by native-PAGE and CD activity staining of crude cell extracts. Analyses with gene-disrupted mutants showed that CD activity resulted from two enzymes: tryptophanase (TNase) encoded by tnaA and cystathionine beta-lyase (CBL) encoded by metC. It was also found that TNase synthesis was induced by the presence of L-cysteine. The tnaA and metC mutants transformed with the plasmid containing the gene for feedback-insensitive serine acetyltransferase exhibited higher L-cysteine productivity than the wild-type strain carrying the same plasmid. These results indicated that TNase and CBL did act on L-cysteine degradation in E. coli cells.

Atomic configuration in core structure of Lomer dislocation in Si0.76Ge0.24/Si

The core structure of a Lomer dislocation in SiGe/Si system has been revealed at atomic level. This is attained by applying the image deconvolution technique in combination with dynamical diffraction effect correction to the high-resolution image taken with a 200 kV field-emission gun high-resolution electron microscope. The Lomer dislocation has a Hornstra-like core. The contrast of the image simulated on the basis of derived atomic configuration is in agreement with that of the experimental image.

Evolution of lower-hybrid-driven current during the formation of an internal transport barrier

Evolution of the lower-hybrid(LH)-driven current profile was measured during the formation of an internal transport barrier (ITB) in a reversed magnetic shear discharge. As the ITB developed, the initially centrally peaked LH-driven current profile gradually turned hollow and was sometimes accompanied by an off-axis peak in the electron temperature profile. These observations indicate the concentration of LH power deposition to the ITB for this case as a result of nonlinear coupling between the LH waves and the target plasma.

Chronic cyclosporin nephropathy: long-term effects of cyclosporin on renal allografts

Cyclosporin (CSA) has significantly reduced both incidence and severity of acute rejection, and brought excellent graft survival rates. Chronic CSA nephrotoxicity seems to be the second most important diagnosis responsible for the late graft failure. CSA-associated arteriolopathy (CAA) is well known as a characteristic lesion of chronic CSA nephrotoxicity by graft biopsies. There are few reports on the long-term outcome of renal transplant patients with biopsy-proven chronic CSA nephrotoxicity after diagnosis of CAA. We conducted two studies, the long-term outcome of the patients with CAA, and the FGS lesion related to CAA. Seventy-four CAA patients continued on CSA therapy after diagnosis of CAA were classified into two groups by outcome of the graft after follow-up: the functioning graft group (n = 30) and the graft-loss group (n = 44). There was no significant difference in severity of CAA grade between the functioning and graft-loss groups. Concomitant lesion of chronic rejection but not severity of CAA was the most important risk factor of graft loss for CAA patients in our study. Of a total of 54 recipients with FGS lesion, 32 patients (59%) were diagnosed as CAA-associated glomerulopathy (CAG) accompanied with severe CAA. Eighteen of 32 CAG patients lost their grafts after follow-up. Their serum creatinine level at biopsy was higher than that of the functioning group; however, there was no significant difference in daily proteinuria at biopsy between two groups. We have tried to reduce CSA dosage to maintain lower blood levels than the usual optimal target levels, but did not discontinue CSA after diagnosis of severe CAA and FGS lesion. In 15 isolated pure CAG patients, those with increasing daily proteinuria exceeding 2 g lost their graft function even after reducing CSA administration. The change in daily proteinuria seems to be a useful indicator for late graft loss in the patients of FGS lesion with severe CAA. CAA is not specific for chronic CSA nephrotoxicity, and FGS lesion is also a non-specific lesion often developed in renal allografts. Our study revealed clinicopathological characteristics of chronic CSA nephrotoxicity. Isolated chronic CSA arteriolopathy of severe degree has a fairly good prognosis under controlled CSA therapy. FGS lesion accompanied by CAA is considered as a new concept of CAG, and increasing proteinuria in patients with CAG is a good indicator for poor outcome. These results will contribute towards an appropriate therapeutic plan for renal transplant patients undergoing long-term CSA treatment.

Does infiltration of neutrophils in peritubular capillaries indicate humoral rejection? A case displaying a characteristic lesion of a significantly high amount of neutrophils in peritubular capillaries at 1-h graft biopsy during transplant operation

We present a case report of a 50-yr-old Japanese woman with a significant accumulation of neutrophils in the peritubular capillaries (PTC) and severe acute tubular necrosis (ATN) at 1-h allograft biopsy during transplant operation from cadaver donor after a cardiac death. Significant accumulation of neutrophils in the PTC is usually valuable diagnostically for acute humoral rejection. However, the patient showed no clinical signs of acute rejection. A second graft biopsy performed on the fifth postoperative day (POD) revealed that both infiltration of neutrophils in PTC and ATN lesions were more aggravated. Neither clinical course nor other morphological findings were compatible with humoral rejection. After the third biopsy of POD 27 revealing acute vascular rejection of moderate degree, acute rejection therapy using methylprednisolone pulse therapy and OKT-3 therapy was performed. Consequently, after a period of delayed graft function requiring haemodialysis for approximately 4 wk, graft function was restored and serum creatinine decreased to 2 mg/dL. Later, we were able obtain information from a paired graft from the same donor. Significant accumulation of neutrophils in the PTC similar to our recipient was also noted in a 1-h biopsy specimen of the paired kidney. This confirmed that the accumulation of neutrophils in the PTC noted in two recipients was transmitted from the donor kidney. The pathogenesis and clinical significance of neutrophils in the PTC has been shrouded in mystery.

Birth of normal calves after intracytoplasmic sperm injection of bovine oocytes: a methodological approach

Intracytoplasmic sperm injection (ICSI) is advantageous when only very few spermatozoa are available for insemination. Bovine spermatozoa were injected individually into matured oocytes using a piezo electric actuator. Spermatozoa were "immobilized", by scoring their tails immediately before injection, or "killed", by repeated freezing and thawing. About 4 h after ICSI, the oocytes with two polar bodies (activated by sperm injection) were selected and treated 5 min with 7% ethanol before further culture. When examined 19-21 h after ICSI, nearly 90% of the oocytes were fertilized normally (two pronuclei and two polar bodies) irrespective of the sperm treatment (immobilization or killing) prior to ICSI, but subsequent preimplantation embryo development was much superior (cleavage 72%: blastocysts 20%) after ICSI with immobilized spermatozoa than by using killed spermatozoa (cleavage 28%; blastocysts 1%). Ethanol activation of bovine oocytes with two polar bodies 4 h after ICSI improved the cleavage (33% versus 72%) and blastocyst (12% versus 20%) rates markedly (P < 0.05). Five normal calves were born after transplantation of ten blastocysts to ten surrogate cows. These results show that piezo-ICSI using immobilized spermatozoa, combined with ethanol treatment of sperm-injected oocytes, is an effective method to produce bovine offspring.

Plasma equilibrium and confinement in a tokamak with nearly zero central current density in JT-60U

A high confinement equilibrium with nearly zero toroidal current in the central region (a "current hole") has been observed for the first time to persist stably for several seconds in the JT-60U tokamak. This observation indicates the possibility of stable tokamak operation without central toroidal current; the central current has previously been believed to be necessary in tokamaks. The radius of the current hole extended up to 40% of the plasma minor radius. It was observed that the current hole was formed by the increase of the off-axis noninductive current.

A potential use of a synthetic retinoid TAC-101 as an orally active agent that blocks angiogenesis in liver metastases of human stomach cancer cells

TAC-101 (4-[3,5-bis(trimethylsilyl)benzamido]benzoic acid) is a novel, synthetic retinoid that is effective against liver metastases of human gastrointestinal cancer cells such as the human stomach carcinoma line AZ-521 in animal models, and is currently in use in phase I cancer trials. However, the mechanism of its antimetastatic action is still poorly understood. Tumor metastasis depends on angiogenesis, and various retinoids have been found to exhibit antiangiogenic activity. Based on these findings we here examined the antiangiogenic effects of TAC-101. Oral administration of TAC-101 (2-8 mg/kg/day) resulted in a drastic suppression of the AZ-521 cell-induced angiogenesis in a mouse dorsal air sac assay system, compared to the vehicle alone. Immunohistochemical analysis with antibody against the endothelial marker CD31 revealed a significant reduction in microvessel density in liver metastases from animals treated with TAC-101 (8 mg/kg p.o.), compared to liver metastases from the untreated control animals. The ability of TAC-101 (8 mg/kg p.o.) to prevent experimental liver metastasis of AZ-521 cells in athymic nude mice was comparable with that of the known angiogenesis inhibitor TNP-470 (30 mg/kg s.c.). TAC-101 also affected angiogenesis in chorioallantoic membranes and some functions of endothelial cells associated with angiogenesis, whereas the retinoid failed to suppress AZ-521 cell proliferation directly. These data suggest that the TAC-101 is an orally active antiangiogenic agent and that this antiangiogenic property may contribute to its efficacy against liver metastasis of human stomach cancer cells.

Mercury pollution in the Tapajos River basin, Amazon: mercury level of head hair and health effects

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and Sao Luiz do Tapajos) on the Tapajos River, an effluent of the Amazon, situated several hundred kilometers downstream from the gold-mining areas. A total of 132 fishermen and their families volunteered for the current study. As was anticipated, the total mercury levels in the head hair collected from the fishing villages were relatively high (14.1-20.8 ppm on the average) and the number of subjects with a high total mercury level over 10 ppm (the least upper bound of a normal value) was 103 (78.0%) in total, along with various symptoms, thereby suggesting wide mercury contamination in the Tapajos River basin. Moreover, in view of the absence of other diseases (e.g., alcoholism or malaria), a high intake of fish containing a methylmercury level, and high hair mercury levels in addition to the various symptoms such as sensory disturbance (especially glove-and-stocking type, which is characteristic of Minamata disease), tremor, failure in two-point discrimination, and slight balancing failure, several subjects examined were diagnosed with mild Minamata disease. The findings obtained suggest, thus, that the mercury pollution in the Amazon should be crucially observed for head hair mercury level and health in a much broader region.

Extinction of expression of the genes encoding haematopoietic cell-restricted transcription factors in T-lymphoma x fibroblast cell hybrids

We previously reported that expression of the T-cell receptor (TCR) alpha and lck genes is extinguished in hybrids between mouse T-lymphoma EL4 cells and mouse fibroblast B82 cells. In the present study, we found that the activities of the TCRalpha minimum enhancer and the lck promoter monitored by the luciferase or chloramphenicol acetyltransferase (CAT) assays were markedly inhibited in the hybrids. Expression of the TCF-1, LEF-1, GATA-3, Ikaros, c-myb and Fli-1 genes, which encode the haematopoietic cell-restricted transcription factors that appear to be responsible for the activities of the enhancer and the promoter, was fully extinguished or markedly suppressed in the hybrids. On the other hand, expression of the transcription factor genes observed in both parental cells, such as the AML1 and c-ets-1 genes, and that of the genes encoding ubiquitously expressed transcription factors, such as the E2A, CREB and c-ets-2 genes, was not significantly suppressed in the hybrids. These results suggest that the genes encoding haematopoietic cell-restricted transcription factors are targets for negative regulation in fibroblastic background and that the repression of these genes may consequently lead to suppression of the promoter and/or enhancer activities of several T-cell-specific structural genes in T-lymphoma x fibroblast cell hybrids.

In vivo complex formation of PU.1 with HDAC1 associated with PU.1-mediated transcriptional repression

We previously reported that overexpression of PU.1, a member of the Ets family of transcription factors, induces differentiation inhibition and apoptosis associated with c-Myc down-regulation in murine erythroleukemia (MEL) cells. To understand the molecular mechanism by which c-Myc is down-regulated due to overexpression of PU.1, we performed luciferase reporter assays using the mouse c-myc promoter. PU.1 repressed the activities of not only the c-myc promoter but also several other promoters. Experiments with deletion mutants of PU.1 revealed that the C-terminal region spanning amino acids (aa) 123-272 including the PEST and ETS domains but not the activation domain was sufficient for this transcriptional repression. It was unlikely that the repression was due to sequestration of a limited amount of CBP/p300 nor pCAF, because overexpression of these co-activators did not relieve PU.1-mediated transcriptional repression. Instead, it was found that the C-terminal aa 101-272 of PU.1 formed a complex with mSin3A and HDAC1 in vivo, which was speculated to be associated with the repression. The C-terminal region of PU.1 also formed a complex with the basic transcription factor TBP in vitro and in vivo. Our results suggest that overexpression of PU.1 induces transcriptional repression in several gene promoters including the c-myc promoter which may be mediated by its complex formation with HDACs.

Quasisteady high-confinement reversed shear plasma with large bootstrap current fraction under full noninductive current drive condition in JT-60U

A quasisteady reversed shear plasma with a large bootstrap current fraction ( approximately 80%) has been obtained for the first time in the JT-60U tokamak. The shrinkage of reversed shear region was suppressed by the bootstrap current peaked at the internal transport barrier (ITB) layer and the ITBs at a large radius were sustained, which, by combination with an H-mode edge pedestal, resulted in a high confinement or 2.2 times the H-mode scaling for 6 times energy confinement time or 2.7 s. Furthermore, a full noninductive current drive was obtained by the bootstrap current and the beam driven current.

Psychrophilic valine dehydrogenase of the antarctic psychrophile, Cytophaga sp. KUC-1: purification, molecular characterization and expression

We found the occurrence of valine dehydrogenase in the cell extract of a psychrophilic bacterium, Cytophaga sp. KUC-1, isolated from Antarctic seawater and purified the enzyme to homogeneity. The molecular mass of the enzyme was determined to be approximately 154 kDa by gel filtration and that of the subunit was 43 kDa by SDS/PAGE: the enzyme was a homotetramer. The enzyme required NAD+ as a coenzyme, and catalyzed the oxidative deamination of L-valine, L-isoleucine, L-leucine and the reductive amination of alpha-ketoisovalerate, alpha-ketovalerate, alpha-ketoisocaproate, and alpha-ketocaproate. The reaction proceeds through an iso-ordered bi-bi mechanism. The enzyme was highly susceptible to heat treatment and the half-life at 45 degrees C was estimated to be 2.4 min. The kcat/Km (micro(-1).s(-1)) values for L-valine and NAD+ at 20 degrees C were 27.48 and 421.6, respectively. The enzyme showed pro-S stereospecificity for hydrogen transfer at the C4 position of the nicotinamide moiety of coenzyme. The gene encoding valine dehydrogenase was cloned into Escherichia coli (Novablue), and the primary structure of the enzyme was deduced on the basis of the nucleotide sequence of the gene encoding the enzyme. The enzyme contains 370 amino-acid residues, and is highly homologous with S. coelicolor ValDH (identity, 46.7%) and S. fradiae ValDH (43.1%). Cytophaga sp. KUC-1 ValDH contains much lower numbers of proline and arginine residues than those of other ValDHs. The changes probably lead to an increase in conformational flexibility of the Cytophaga enzyme molecule to enhance the catalytic activity at low temperatures.

Increased transglycosylation activity of Rhodotorula glutinis endo-beta-glucanase in media containing organic solvent

The transglycosylation of p-nitrophenyl-beta-D-cellotrioside to cellotetraose catalyzed by endo-1,4-beta-glucanase (cellulase, EC 3.2.1.4) from a psychrotrophic yeast, Rhodotorula glutinis KUJ 2731, was increased by addition of a miscible organic solvent in the reaction mixture. Among various organic solvents tested, acetone was most effective. The transglycosylation activity increased with an increase in acetone concentrations, while hydrolysis activity was suppressed. The transglycosylation preferably occurred at acidic pH with the optimum pH at 2 in 10 mM Gly-HCl buffer. The optimum temperature of transglycosylation was found to be 50 degrees C in the presence of 40% acetone.

Pentoxifylline improves in vitro fertilization and subsequent development of bovine oocytes

The purpose of this study was to examine whether pentoxifylline improves in vitro fertilization and developmental rates of bovine oocytes. In the first experiment, we examined the effects on the fertilization rate of various concentrations of pentoxifylline (0-7.5 mM) combined with heparin (10 IU/mL). In the second experiment, we examined fertilization cleavage and blastocyst rates after frozen-thawed spermatozoa, obtained from four different bulls, were incubated with heparin (10 IU/mL) with or without caffeine (5 mM) or pentoxifylline (5 mM). In the first experiment, a significantly higher fertilization rate was obtained in heparin containing 5 mM pentoxifylline compared to that in heparin alone or in heparin containing 7.5 mM pentoxifylline (86% vs 60% vs 64%, respectively). The percentage of monospermy in 5 mM pentoxifylline (81%) was significantly higher than in heparin alone (57%). In the second experiment, the interactions among Bulls A, B, C, and D; between treatments (pentoxifylline-with-heparin, caffeine-with-heparin and heparin alone), and between bulls and treatments were analyzed for the number of oocytes penetrated, monospermic oocytes, cleaved oocytes and blastocysts. Among bulls, there was a significant difference in the number of oocytes penetrated (P < 0.01), monospermic oocytes (P < 0.05), cleaved oocytes (P < 0.001), and blastocysts (P < 0.001). Between treatments, there was a significant difference in the number of oocytes penetrated (P < 0.001), monospermic oocytes (P < 0.01) and cleaved oocytes (P < 0.001). Interaction between bulls and treatments was observed for the number of oocytes penetrated (P < 0.05). Individually, for Bulls A, C and D, the numbers of oocytes penetrated and monospermic oocytes in pentoxifylline-with-heparin were significantly higher than in heparin alone. For Bull D, significantly higher results were obtained for the number of oocytes penetrated, monospermic oocytes, cleaved oocytes and blastocysts in pentoxifylline-with-heparin compared to caffeine-with-heparin and heparin alone (P < 0.05). These results suggest that treating sperm with 5 mM pentoxifylline in combination with heparin is effective for bovine in vitro fertilization and it that this treatment is effective even for bulls that produce low fertilization and blastocysts after sperm treatment with caffeine-with-heparin or heparin alone.

Immunohistochemical studies on the differential maturation of three types of olfactory organs in the rats

Differential maturation of three types of olfactory organs, the olfactory epithelium (OE), the vomeronasal organ (VNO) and the septal olfactory organ of Masera (MO), was examined immunohistochemically in embryonic and newborn rats by the use of antiprotein gene product 9.5 (PGP 9.5) serum. These olfactory organs were derived in common from the olfactory placode as neuroepithelia. In the OE, PGP 9.5-immunopositive olfactory cells first appeared at 13 days of gestation. The OE maturated completely, and showed the same cytological features as in the adult at 20 days of gestation. The MO first appeared as a dense mass of PGP 9.5-immunopositive sensory cells on the most ventrocaudal part of the nasal septum at 15 days of gestation and was evidently isolated from the OE by the decrease of immunopositive cells in the intercalated epithelium between the OE and the MO at 20 days of gestation. However, even at 7 days after birth, the MO did not complete its development and contained sensory cells aggregating in the mass. The VNO was separated from the nasal cavity at 13 days of gestation as a tubular structure of a neuroepithelium including PGP 9.5-immunopositive sensory cells. These cells gradually increased in number in the sensory epithelium of the VNO and extended their dendritic processes to the free surface at 7 days after birth. These findings clarified the differential maturation of these olfactory organs. That is, the OE completes its development before birth, while the MO and VNO after birth.

Relationship between cytocidal activity and glutathione-S-transferase inhibition using doxorubicin coupled to stereoisomers of glutathione with different substrate specificity

To determine the cytotoxic mode of action of a glutathione (GSH)--doxorubicin (DXR) conjugate, which exhibited potent cytotoxicity against various multidrug-resistant as well as DXR-sensitive cell lines, the molecular interaction between covalent GSH--DXR conjugates and glutathione-S-transferase (GST), a possible molecular target of the conjugates, was investigated. The following four GSH molecules with stereoisomeric forms were prepared: L-Glu--L-Cys--Gly (LL-GSH), D-Glu--L-Cys--Gly (DL-GSH), L-Glu--D-Cys--Gly (LD-GSH) and D-Glu--D-Cys--Gly (DD-GSH). The enzymic activity of GST against each GSH stereoisomer was 88, 38, 8 and 4 nmol/mg/min, respectively, suggesting that the L-form cysteine residue in the molecule was an important substrate of GST. Addition of DXR conjugated with each isomer (10 microM) to a GSH-containing GST assay mixture inhibited the GST activity to 32% for LL-GSH--XR, 16% for DL-GSH-DXR and 61% for LD-GSH-DXR as compared with the solvent control. Moreover, IC50 values for these conjugates were 30, 20 and 250 nM, respectively. The cytocidal activity of each conjugate corresponded to the substrate specificity of GST activity for the GSH isomer. These conjugates bound to the GST molecule, and the binding ability was 0.746, 0.627 and 0.462 mol/mol of GST for LL-GSH--XR, DL-GSH-DXR and LD-GSH--XR, respectively. These findings suggested that GSH--DXR interacted with the substrate-binding site of the GST molecule and inhibition of GST activity exhibited potent cytotoxicity.

Acute humoral rejection of kidney allografts in patients with a positive flow cytometry crossmatch (FCXM)

The patients with a positive flow cytometry crossmatch (FCXM) are categorized as a high-risk group causing hyperacute or accelerated acute rejection after kidney transplantation. According to the successful results of ABO-incompatible renal transplantation, we have performed the living related transplant operations in the recipients with positive FCXM for donor T cells, but having a negative complement-dependent lymphocytotoxic reaction test. We have followed the clinical course of 4 FCXM-positive patients, and 2 of them have developed acute humoral rejection. We report the strategies for FCXM-positive living kidney transplantations and the characteristics of pathological findings of acute humoral rejection in FCXM-positive renal transplants. We have had few episodes of acute humoral rejection in ABO-incompatible kidney transplantations under immunosuppressive regimens, including cyclophosphamide, but 2 patients of 4 with FCXM-positive kidney transplantations developed acute humoral rejections. The differences in immunosuppressive regimen between ABO-incompatible and FCXM-positive kidney transplantations concern anti-lymphocyte globulin (ALG) and splenectomy. We have not performed splenectomy and ALG administration in FCXM-positive kidney transplantations. Severe acute rejection episodes have been experienced on post-operative days 7 and 9 in 2 of 4 FCXM-positive recipients. The early acute rejection episodes were clinically and pathologically diagnosed as typical humoral rejections. We have examined an immunofluorescent study to prove the diagnosis of humoral rejection in FCXM-positive kidney transplantations; both immunoglobulin M and C3 were positive for the whole course of humoral rejection. The 2 patients with acute humoral rejection recovered after treatment with double filtration plasmapheresis or plasma exchange to remove their anti-donor antibodies. The gold standard of success in FCXM-positive kidney transplantations is to suppress the production and reduce the level of anti-donor antibodies after transplant operations.

Light regulation of circadian clock-controlled gene expression in rice

Using transgenic rice seedlings expressing a firefly luciferase (luc) gene under the control of a rice CAB (chlorophyll a/b binding protein) promoter, we demonstrated how light affects circadian clocks in the transcription of the CAB gene. Rhythmic luc expression was observed for more than 5 d under constant light and dark (DD) conditions after light/dark entrainment. After a light pulse was applied at different time points in DD various temporal patterns of CAB gene expression were individually observed. We first examined two distinct properties related to the entrainment mechanism of the circadian clock: fluence-rate dependence of free-running periods (FRPs) and phase resetting by a light pulse. Although fluence-rate dependent shortening of FRP was demonstrated, the FRP in DD was almost equal to that in constant light of a middle fluence-rate, indicating that this fluence-rate dependence may not fully describe the entrainment of the circadian clock in rice. Typical phase responses of the circadian clock by a single light pulse were also observed at the transcriptional level in rice seedlings. Thus, the phase resettings upon the light/dark transitions of daily cycles may be sufficient to explain the entrainment mechanisms of rice. We have further demonstrated that, in addition to having a gating effect to acute response, a light pulse can activate the circadian clock-controlled CAB1R gene expression at the first circadian peak in a phase-dependent manner. This suggests that light activates circadian clock activity in the diurnal CAB gene expression under daily light/dark cycles.