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Recent studies on genetic variability have revealed different patterns of genetic structure among populations of marine decapod species with wide geographical distribution. The hermit crab Clibanarius antillensis has a broad distribution along the western Atlantic Ocean, from south Florida (United States) to Santa Catarina (Brazil). This factor, in addition to differences in larval morphology and in adult coloration, makes this species a good model for studies on intraspecific variations. Therefore, we evaluated the molecular and morphological variability of C. antillensis along its distribution in order to check the levels of population structure. The results were based on the morphological analyses of 187 individuals and 38 partial sequences of the mitochondrial gene 16S rRNA and 46 of cytochrome c oxidase subunit I (COI) from specimens whose locations covered the whole species distribution. The molecular analyses did not show any apparent population structure of C. antillensis. This result was corroborated by the morphological analyses since the characters analyzed did not show any pattern of variation. Our results may be explained by a set of factors, such as the dispersive potential of the species and the absence of barriers that could prevent gene flow. In addition, high genetic diversity was observed, mainly for COI, which may be explained by the historical processes of the species, which seem to be in almost constant expansion in the last 700,000 years and experienced no genetic bottleneck. Apparently, this species was little affected by the climate fluctuations of Pleistocene. Additionally, our morphological analyses allowed us to present herein a redescription of the studied species since we noted differences from the characters in the diagnosis.

AIMS Using substrate-induced gene-expression (SIGEX) screening on subseafloor sediment samples from the Nankai Trough, Japan, we identified gene fragments showing an induction response to metal ions. METHODS AND RESULTS Environmental DNA libraries in Escherichia coli host cells were tested by the addition of metal ions (Ni2+ , Co2+ , Ga3+ or Mo6+ ), followed by cell sorting of clones exhibiting green fluorescence upon co-expression of green fluorescence protein downstream of the inserted gene fragments. One clone displayed Ni2+ -specific induction, three clones displayed Ga3+ -specific induction and three clones displayed an induction response to multiple metal ions. DNA sequence analysis showed that a variety of genes showed induction responses in the screened clones. CONCLUSIONS Using the SIGEX approach, we retrieved gene fragments with no previously identified response to metal ions that exhibited metal-ion-induced expression. This method has the potential to promote exploration of gene function through gene-induction response. SIGNIFICANCE AND IMPACT OF THE STUDY We successfully linked gene-induction response with sequence information for gene fragments of previously unknown function. The SIGEX-based approach exhibited the potential to identify genetic function in unknown gene pools from the deep subseafloor biosphere, as well as novel genetic components for future biotechnological applications.

In turbine blade machining from a near net shape (e.g., forged workpiece), it is difficult to use a touch trigger probe for measuring the mounting angle of the workpiece due to its uncertain free-form surface. Therefore, non-contact measurement is required to determine the setup condition of the workpiece. Recently a high-performance laser displacement sensor has been able to measure glossy metal surfaces because of the progress in its sensing device. Using such a high-performance sensor, the non-contact type on-machine measurement system has been developed. It was installed on the multi-functional machine tool to determine validity of the system. This system measured the turbine blade cross-section to compare with CAD data and the measurement data by coordinate measuring machine (CMM). As a result, validity of this system for measuring a turbine blade was proved. We have proposed some application using this measurement system. The application enables optimal machining of a turbine blade from a near net shape at an appropriate phase. This contributes to minimizing the size of expensive material and the machining time.

Recently, visualization of urban scenes with various information attracts attention. For the transmission of urban scenes, virtual reality has been widely used. Since the virtual reality requires comprehensive and detailed three dimensional models, the manual dependent modelling takes a lot of time and effort. On the other hand, it has been tackled that various data is superimposed on the scene which the users see at the time instead of comprehensive modelling, which is well known as augmented reality (AR). Simultaneous localization and mapping (SLAM) has been attempted using simple video cameras for the AR. This method estimates exterior orientation factors of the camera, and three dimensional reconstructions of feature points simultaneously. The method, however, has been applied to only small indoor space. This paper investigates the applicability of the popular method of SALM to wide outdoor space, and improves the stability of the method. Through the application, the tracked feature points successfully are greatly reduced compared with application in indoor environment. According to the experimental result, simple markers or GPS are introduced as auxiliary information. The markers gives the stability of optimization, and GPS gives real scale to AR spaces. Additionally, feature points tracking method is modified by assigning amplitude of displacement and depth. The effect of the markers and GPS are confirmed. On the other hand, some limitations of the method are understood. As a result, more impressive visualization will be accomplished.

InN nanocolumns were grown on (000 1) sapphire substrates by radio-frequency plasma-assisted molecular-beam epitaxy, simply with substrate nitridation, InN nucleation, and high V/III growth conditions. Here, the InN nucleation was conducted by forming In droplets on the nitridated substrates and subsequently nitriding these In droplets. We investigated the growth evolution of InN nanocolumns and the growth-temperature dependence of the morphology. X-ray rocking curves (XRC) for the (0002) reflection of the samples basically consisted of two components: a broad peak and a very sharp one. We propose that the broad peak came from the lower part of relatively short nanocolumns and the near-interface region of relatively long nanocolumns. In contrast, the sharp peak came from the (strain-free) upper part of relatively short nanocolumns and the high-crystal-quality region apart from the interface in relatively long InN nanocolumns. The relative intensity of the latter to the former increased with growth time. The shape of the nanocolumns varied with growth temperature: nanocolumns grown at 380 and 420 °C had a taper-like appearance, but the top broadened with increasing growth temperature, becoming broader at the top than the base at 470 and 500 °C. When we grew InN nanocolumns under the same conditions, but without surface nitridation, the subsequent columns were not all along a c-axis. If In droplets were not used, then columns did not form. Thus, both the surface nitridation and In droplets were needed to form c-axis aligned nanocolumns.

The hepatitis B virus (HBV) and the human immunodeficiency virus type 1 (HIV-1) can infect cells of the lymphatic system. It is unknown whether HIV-1 co-infection impacts infection of peripheral blood mononuclear cell (PBMC) subsets by the HBV. Aims To compare the detection of HBV genomes and HBV sequences in unsorted PBMCs and subsets (i.e., CD4+ T, CD8+ T, CD14+ monocytes, CD19+ B, CD56+ NK cells) in HBV mono-infected vs. HBV/HIV-1 co-infected individuals. Methods Total PBMC and subsets isolated from 14 HBV mono-infected (4/14 before and after anti-HBV therapy) and 6 HBV/HIV-1 co-infected individuals (5/6 consistently on dual active anti-HBV/HIV therapy) were tested for HBV genomes, including replication indicative HBV covalently closed circular (ccc)-DNA, by nested PCR/nucleic hybridization and/or quantitative PCR. In CD4+, and/or CD56+ subsets from two HBV monoinfected cases, the HBV polymerase/overlapping surface region was analyzed by next generation sequencing. Results All analyzed whole PBMC from HBV monoinfected and HBV/HIV coinfected individuals were HBV genome positive. Similarly, HBV DNA was detected in all target PBMC subsets regardless of antiviral therapy, but was absent from the CD4+ T cell subset from all HBV/HIV-1 positive cases (P

Hydroxyapatite/hyaluronic acid (HAp/HyA) and hydroxyapatite/chondroitin sulfate (HAp/ChS) microparticles, which show the high adsorption ability of proteins, high biocompatibility and osteoconductivity, are potential scaffolds for a time-controlled BMP release. The present study evaluated the biocompatibility and osteoconductivity of the composites after injection into bone defect. Drilled bone holes were made at tibia and femur of Japanese white rabbits, and HAp/HyA or HAp/ChS was implanted into each bone hole using an injection syringe. After 2 and 4 weeks of implantation, rabbits were sacrificed and histological observations were conducted with HE, TRAP, and ALP staining. Histological observations revealed that HAp/ChS has superior biocompatibility compared with HAp/HyA, and 20% HAp/ChS promotes bone formation as well as osteoblast activities compared with lower ratios of HAp/ChS.

In this paper, a new method for reducing scan shifts is presented. Scan design is one of the most popular designs for test method for sequential circuits. However, for circuits with many flip-flops, it requires a long test application time and high test-data volume. Our new scan method utilizes two configurations of scan chains, a folding scan tree and a fully compatible scan tree to alleviate these problems. It is observed that uncompacted test patterns typically contain a large fraction of don't care values. This property is exploited in the fully compatible scan tree to reduce scan shifts without degrading fault coverage. Then, a folding scan tree is configured to further reduce the length of scan chain and scan shifts. Experimental results on benchmark circuits show that this scan method can significantly reduce scan shifts.

Nanocomposites of hydroxyapatite / chondroitin sulfate or hyaluronic acid were prepared by a wet method through a self-organization. In the nanocomposites, the c-axis of hydroxyapatite nanocrystals was oriented along the longitudinal axis of the aggregations. The spherical porous microparticles by using a spray drying method were developed with the size range of 1.0 to 20 µm, specific surface area of c.a. 100 m2g-1 and porosities of over 60vol%. No thermal decomposition of polysaccharides was occurred through the spray drying processes. It is note worth that the zeta-potential of the microparticles were gradually changed to be negative value of -35mV against the content of polysaccharides. The animal experiments implanted under the skin showed that the HAp/ChS had a good biocompatibility for 4 week implantations. The spherical microparticles will be applicable to create more complicated composites and drug carriers.

There have been few descriptions of the site of attachment onto the triquetrum, the so-called meniscal homologue, of the triangular fibrocartilage complex (TFCC). We have investigated the sites of attachment onto the triquetrum of 87 TFCCs collected from embalmed cadavers. All TFCCs were smoothly attached to the triquetrum. In 79 (46 cases, 90%) they were attached to the triquetrum and fifth metacarpal bone, and in eight (5 cases, 10%) they were attached widely on the articular surface of the triquetrum. It is necessary to have accurate positional information about the normal triquetrum and TFCC in order to perform arthroscopy. The meniscal homologue attached to the triquetrum is smooth in almost all cases. In about 10% of joints the TFCC is attached to the lunotriquetral ligament, either partly or completely obscuring the articular surface of the triquetrum.

We investigated tritium (T) release behavior from silica glass. The specimens were 8 kinds of commercially available silica glass. T was injected by the 6Li (n,α)T reaction of sintered pellets of lithium oxide (Li 2 O) into the silica glass with thermal neutrons in JRR-2 (VT-8) up to 5 × 10 18 neutrons/cm 2 at ambient temperature (about 350 K). After irradiation, the Li 2 O pellets were removed from the silica glass, and T release from the silica glass was measured in a flow of hydrogen (H 2 ) or ammonia (NH 3 ) sweep gas at atmospheric pressure at a constant heating rate of 2 K/min between 675 K and 1375 K with a proportional counter. In the case of H 2 sweep gas, a maximum tritium release rate was observed around 1023 K, while in the case of NH 3 sweep gas, two peaks around 1023 K and around 1123 K or a peak around 1123 K with a shoulder were obserbed. After the experiments of T release, FT-IR spectra showed a decrease of SiOH bands at 3650 cm -1 . On the other hand, no changes in intensities at 2250 cm -1 due to SiH were observed for both samples before and after T release.

A spatial site-control method for InAs quantum dots (QDs) is proposed and demonstrated using ultrahigh vacuum in situ processing. Regular InAs QD arrays are initially prepared as strain templates on GaAs surfaces by the scanning tunneling microscope (STM) probe-assisted site-control technique. Multiple layers of InAs Stranski–Krastanov QDs are then grown with GaAs spacers for strain-induced vertical alignment above the regular QD arrays, resulting in three-dimensional QD lattices. Step-by-step STM observations reveal the growth mode of QDs in the vertical alignment process. ? 2002 Elsevier Science B.V. All rights reserved.

We performed dephasing time characterization of InAs quantum dots waveguide and observed photon echo signal by time-resolved degenerate four-wave mixing. For large dots with a diameter of 40 nm, a relatively long T2 of330 f s was obtained. For small dots with a diameter of30 nm, a short T2 of230 f was obtained. Based on a comparison ofthe samples, it was suggested that this increase in T2 in large dots was due to the size dependence ofcarrier–LO phonon coupling. ? 2002 Elsevier Science B.V. All rights reserved.

This paper describes micro-photoluminescence (PL) analysis of site-controlled QDs (SCQDs) grown using a novel in-situ MBE growth technique in which sites of self-assembled InAs QDs are controlled by forming nanometer deposits using a scanning tunneling microscope (STM) probe. We found from the temperature dependence of PL that the carrier collection at QDs at low temperature is limited by carrier diffusion in the wetting layer. The analysis of PL data considering this effect has indicated that individual QDs grown have high crystalline quality in spite of the addition of an artificial STM process during growth.

Several new loci were identified by a comprehensive analysis of loss of heterozygosity (LOH) using a subtraction library between matched normal and renal cell carcinoma (RCC) tissues. A total of 187 clones from the library, with a complexity of 1x10(4), were mapped, and 44 clusters of the mapped loci were subjected to LOH analysis using microsatellite markers. A total of 27 loci, which exhibited frequencies of LOH of at least 10% among 44 tumors, mostly clear-cell RCC, included several loci that were reported previously, such as, the von Hippel-Lindau gene, adenomatous polyposis coli, and interferon regulatory factor-1, as well as new loci, at 5q32-q34, 6q21-q22, 8p12, and others. These loci exhibited LOH among 11.8-93.8% of tumors, and most, if not all, were derived from the sites of hemizygous deletions. The minimum regions of LOH of chromosomes 5, 6, and 8 were 9.0, 10.3, and 0.775 Mb, respectively. The average distance between the cloned fragments on the chromosomes was 2.2 Mb in 187 clones, indicating that the minimum LOH size expected from this subtraction analysis was roughly 50 kb. Therefore, the strategy described here provides comprehensive analysis of LOH sites, which were mostly caused by hemizygous deletions.

Several genetically engineered mouse models are currently being examined for potential use in cancer hazard identification. We have undertaken an interlaboratory comparison of the performance of the CB6F1-Tg rasH2 transgenic mouse in cancer bioassays concurrently conducted in the United States and Japan. Chemicals selected for study included known human carcinogens (melphalan and cyclosporin A) and known rodent carcinogens (p-cresidine and vinyl carbamate) tested at carcinogenic doses, and non-carcinogens (p-anisidine and resorcinol) tested at appropriate high doses. Because of abdominal adhesions caused by the intraperitoneal dosing vehicle, melphalan was excluded from the study results. The remaining five studies showed similar results between the two laboratories conducting each study. Vinyl carbamate gave the strongest positive response inducing lung adenomas and carcinomas and splenic hemangiosarcomas. p-Cresidine was considered positive for urinary bladder transitional neoplasia. Cyclosporin A, p-anisidine, and resorcinol were negative in all studies. Although only five chemicals were successfully tested in this interlaboratory comparison, there was good concordance in outcome for the strong carcinogens and for the non-carcinogens. Successful testing of chemicals with less carcinogenic potential may require modifications in study design to include more animals and longer study duration.

The fungicide isoprothiolane (diisopropyl 1,3-dithiolane-2-ylidenemalonate) decomposes to the diisopropyl esters of malonic acid (DM), chloromalonic acid (DCM) and dichloromalonic acid (DDCM) upon aqueous chlorination. In this study, the cytotoxicity of these compounds was examined using rat hepatocytes cultured on Matrigel. DCM and DDCM caused hepatocellular death at concentrations0.5 mM, while DM had no effect on the cell viability even at the maximum concentration examined (4 mM). Significant lipid peroxidation, measured as 2-thiobarbituric acid reactive substances, was observed in both DCM- and DDCM-treated hepatocyte cultures, and was significantly enhanced by pretreatment with 0.1 mM bis(p-nitrophenyl)phosphate (BNPP), a carboxylesterase inhibitor. When both BNPP and SKF-525A, a cytochrome P450 inhibitor, were present in the medium, DCM-induced cytotoxicity and lipid peroxidation were significantly suppressed compared to cultures with BNPP-treatment alone. By contrast, the DDCM-induced cytotoxicity was not affected by the combined pretreatment of SKF-525A and BNPP. These results indicate that DCM is metabolically activated by cytochrome P450 in an ester form, while DDCM is activated by a mechanism other than one involving cytochrome P450. To further elucidate the cytochrome P450 isozyme involved in the metabolic activation of DCM, microsomal lipid peroxidation was studied in vitro using microsomes from rats treated with beta-naphthoflavone, musk xylene, phenobarbital, pyrazole, or dexamethasone. Among these preparations, the microsomes from dexamethasone-treated rats showed the most extensive lipid peroxidation in the presence of DCM, and the lipid peroxidation was enhanced by BNPP as observed in hepatocyte cultures. These findings suggest the possible involvement of cytochrome P450 3A in the metabolic activation of DCM.

A new family of the 1T compounds is prepared in the NbS 2 –IrS 2 system and the NbSe 2 –IrSe 2 system. The end members of the above systems do not crystallize into the 1T structure. In the NbS 2 –IrS 2 system, the structure variation from the 2H a structure to the pyrite structure through 1T structure has been observed as the average number of the valence electrons per atom increases. Also, in the NbSe 2 –IrSe 2 system, the structure variation from the 4H a structure to the pyrite structure through 1T structure has been observed as the average number of the valence electrons per atom increases. The relative structural stability of the 1T structure in comparison with the 2H a and the pyrite structures is discussed. The electrical resistivity has been measured from room temperature to 30 K, and the magnetic susceptibility has been measured from room temperature to 5 K. The 1T compounds of those systems show semiconductive and weak-paramagnetic behavior.

An optical high-frequency pulse generation method with wavelength tunability is presented by taking advantage of vernier-type gratings in a distributed Bragg reflector laser diode. Experimental results showed that sinusoidal optical pulses, whose lasing wavelengths were tunable, were created with repetition frequencies around 30 GHz. The widths of the radio frequency spectra, furthermore, were drastically reduced by means of mode locking with externally injected optical pulses.

Populations of Diaptomus leptopus (Copepoda: Calanoida) and other calanoid copepods exhibit varying degrees of sexual size dimorphism. We examined whether intraspecific or interspecific variation in dimorphism could be explained by allometry, and we examined the relationship between adult size attained and development rate to determine any relationship between the two. We compared the degree of sexual size dimorphism in D. leptopus and in other calanoid copepods inhabiting temporary and permanent habitats. Allometry did not explain variation in sexual size dimorphism within or among populations or among species. Permanence of habitat affected the degree of dimorphism: dimorphism was greater within and among species inhabiting temporary environments. Non-significant differences in development rate were found among populations and significant differences were found between sexes of D. leptopus when reared under identical laboratory conditions: males developed more rapidly than females but there was no general relationship between development rate and adult size. Potential adaptive hypotheses to explain the differences between populations inhabiting temporary and permanent habitats are discussed.

The interaction of L-selectin and its ligand is widely accepted to mediate leukocyte rolling and adhesion on the endothelial surface. Although L-selectin is ubiqultously expressed on lymphoid cells, its role in execution of lymphocyte functions is unknown. By flow cytometric analysis using mAb specific for sulfatide, a putative ligand for L-selectin, we found that sulfatide was selectively expressed on B cells, but not on T cells. To elucidate the involvement of L-selectin and its ligand in B cell activation, the present study was undertaken to investigate effects of sulfatide on T cell-dependent and -independent Ig production by B cells. In pokeweed mitogen-stimulated cultures, addition of sulfatide resulted in almost complete inhibition of Ig production by B cells in the presence of memory CD4+ T cells, whether L-selectin-positive or -negative. A similar inhibition of Ig production by sulfatide was found when B cells were stimulated with Staphylococcus aureus Cowan I and IL-2. Unlike sulfatide, a desulfated form of sulfatide, galactosylaceramide, did not show any effects on Ig production by B cells. Maximal inhibition of Ig production was observed when sulfatide was added at the early period of culture. Sulfatide suppressed effectively proliferation of B cells, but not of T cells. Sulfatide competed the binding of anti-L-selectin mAb to B cells, suggesting it could interfere B cell activation by blocking L-selectin function. The results suggest a novel role of the L-selectin/its ligand system in the initiation of B cell activation.

Pattern dependence of the growth rate and Ge content in selective epitaxial Si1−xGex growth using reduced‐pressure chemical vapor deposition has been examined for the SiH2Cl2‐GeH4‐H2 system. Contrary to selective epitaxial Si growth where pattern dependence diminishes at low growth temperatures, the growth rate of selectively grown Si1−xGex layers depends on the ratio of the exposed Si area to the oxide‐covered area on a wafer, at temperatures as low as 600 °C. The Ge content in the layers also depends on the ratio, and the dependence is greater at higher temperatures. Adding HCl to the gas phase decreases the pattern dependence of both growth rate and Ge content. Although, in terms of the growth rate, an optimum HCl flow rate for pattern‐insensitive growth exists, the Ge content in the layers is always higher for the wafer with a smaller exposed area.Pattern dependence of the growth rate and Ge content in selective epitaxial Si1−xGex growth using reduced‐pressure chemical vapor deposition has been examined for the SiH2Cl2‐GeH4‐H2 system. Contrary to selective epitaxial Si growth where pattern dependence diminishes at low growth temperatures, the growth rate of selectively grown Si1−xGex layers depends on the ratio of the exposed Si area to the oxide‐covered area on a wafer, at temperatures as low as 600 °C. The Ge content in the layers also depends on the ratio, and the dependence is greater at higher temperatures. Adding HCl to the gas phase decreases the pattern dependence of both growth rate and Ge content. Although, in terms of the growth rate, an optimum HCl flow rate for pattern‐insensitive growth exists, the Ge content in the layers is always higher for the wafer with a smaller exposed area.

An important goal for the investigation of the proliferation of mammalian cells is to establish a fully defined condition for culturing them in vitro. Here, we report establishment of a fully defined culture condition that supports the primary culture of normal c-kit+IL-7 receptor (IL-7R)+ B precursor cells without the aid of stromal cell lines. This defined culture condition contains IL-7, the ligand for c-kit, transferrin, insulin, and bovine serum albumin as protein components. By using the cell lines derived from RAG2(-/-) mice, which do not differentiate into c-kit- stage, we have evaluated the role of each protein in the cell cycle progression of c-kit+IL-7R+ B precursor cells. Since B precursor cells can grow without insulin, c-kit remains a sole functional receptor tyrosine kinase for their growth. While both c-kit ligand (KL) and IL-7 are the requisite molecules for sustained proliferation of B precursor cells, each molecule plays distinct roles. IL-7 starvation results in prompt arrest of the cells at G1. An accumulation of the cells in the mitotic phase was also detected. Thus, the major role of IL-7 is to regulate the G1/S transition and the process of cytokinesis of B precursor cells. Although prolonged KL starvation over 48 h resulted in accumulation of G1 cells, its effect could not be detected within 24 h, which is long enough for all the cells to complete one cell cycle. This suggests that KL might be involved in the cell cycle progression of B precursor cells in a manner that its signal could still be effective in the one or two cell cycles that follow. Although molecular nature of the signals underlying the present observation awaits future investigation, the method described in this report would provide a useful model system for investigating the signaling pathways that are involved in the cell cycle progression of B precursor cells.

The number of lung resection for patients with lung cancer has been increasing lineally for last two decades in Japan. It reached more than 30,000 in 2009. Subsequently those combined with chronic obstructive pulmonary disease (COPD) also have increased. As pulmonary vascular bed has already been lost to some extent due to chronic alveolar destruction, a careful preoperative physiologic assessment according to a guideline by American College of Chest Physicians (ACCP) or European Respiratory Society( ERS)/European Society of Thoracic Surgeons( ESTS) is important to select patients to be underwent lung resection within acceptable risk. The process to evaluate the risk of lung resection for a lung cancer patient has three steps structured by forced expiratory volume in 1 sec( FEV1), diffusion capacitiy for carbon monoxide (DLco), and exercise capacity. We suggested that it would be more practical to add global initiative for obstructive lung disease( GOLD) staging of each patient and distribution of emphysematous lung obtained by functional imaging modarities to the pathway of flow chart of the guideline. Some patients with very low FEV1 demonstrate increase in FEV1 after lung resection by so called lung volume reduction effect. To utilize lots of findings and experiences obtained from lung volume reduction surgery( LVRS) contributes to select patients with lung cancer and COPD and to perform lung resection and perioperative care properly.

Ribozymes are potentially powerful tools for the suppression of intracellular gene expression. However, the few reports that exist of their activities in bacteria have described mixed success. Chuat and Galibert (Chuat, J.-C., and Galibert, F. (1989) Biochem. Biophys. Res. Commun. 162, 1025-1029) failed to detect any trans-activities of hammerhead ribozymes in Escherichia coli, while Sioud and Drlica (Sioud, M., and Drlica, K. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 7303-7307) reported complete inhibition of expression of the gene for a nonbacterial protein, HIV-1 integrase, by trans-acting hammerhead ribozymes in E. coli. It is of interest to determine whether ribozymes can really be used in natural bacterial systems (Altman, S. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 10898-10900). We now report that a ribozyme designed to cleave the A2 gene of RNA coliphage SP, when transcribed from a plasmid in E. coli caused failure of the proliferation of progeny phage. Inactive ribozymes with altered catalytic sequences did not affect phage growth. These results indicate that it is mainly the catalytic activity of the ribozyme and not its function as an antisense molecule that is responsible for suppressing the proliferation of the RNA phage. Moreover, an analysis based on numbers of plaque-forming units and the function of the A2 protein indicated that antisense RNA may successfully compete with ribosomes in targeting mRNA while ribozymes in this study may not compete with ribosomes in naturally occurring bacterial transcription/translation-coupled systems.

To examine the in vivo role of c-kit receptor in B lymphopoiesis we have evaluated precursor B cell populations expressing c-kit in mouse bone marrow and the effects on B cell genesis of administering a neutralizing anti-c-kit mAb, ACK2. Double immunofluorescence labeling and mitotic arrest were used to examine bone marrow cells from BALB/c mice. Almost one-half of TdT+ cells and one-quarter of B220+ cells coexpressed c-kit, mainly at low intensities, and were actively proliferating in vivo. c-kit+ cells that lacked B lineage markers expressed c-kit in high intensities and entered mitosis at an exceptionally rapid rate. In ACK2-treated mice, erythroid and granulocytic cells were almost completely absent from the bone marrow, whereas, in contrast, B lymphopoiesis was stimulated. Pre-B cells expressing cytoplasmic mu-chains; as well as TdT+B220+ cells before mu expression, were increased two- to fourfold in number and production rate. IgM-bearing B lymphocytes were increased in bone marrow and spleen. The results demonstrate that many early precursor B cells in mouse bone marrow constitutively express c-kit receptor. The failure of ACK2 treatment to block B lymphopoiesis, however, suggests that c-kit receptor function is not essential for precursor B cell development in vivo, but can be replaced by alternative signaling systems. The stimulation of B cell genesis by ACK2 treatment may reflect a conferred advantage in the competition for microenvironmental factors which underlies the balance between B lymphopoiesis and other hemopoietic lineages in vivo.

We have designed, fabricated, and characterized efficient optical delay lines for ultrashort pulses based on photonic crystal waveguides formed by coupled defects. The basic structure consists of one-dimensional cylindrical air holes formed in silicon on silicon dioxide ridge waveguides. The defects are created by intentionally increasing the separation of two neighboring air holes. Through proper design, quasiflat impurity bands located at ∼1.55 μm can be successfully obtained. In addition, the wavelength tunability of the impurity bands was clearly demonstrated. Good agreement was found between the experimental observations and numerical simulations.