Application of a phosphite dehydrogenase gene as a novel dominant selection marker for yeasts

The use of antibiotic resistance markers in the commercial application of genetically modified microorganisms is limited due to restrictions on the release of antibiotics and their resistance genes to the environment. To avoid contamination by other microorganisms, the development of a dominant selection marker with low environmental risks is still needed. Here we demonstrated a new selection system for Schizosaccharomyces pombe and Saccharomyces cerevisiae using a bacterial phosphite dehydrogenase gene (ptxD). A Sz. pombe transformant carrying ptxD under a strong promoter or on a multicopy plasmid grew on a minimal medium containing phosphite (Pt) as a sole source of phosphorus. To adapt this system to S. cerevisiae strains, codon optimization of ptxD was necessary. The codon-optimized ptxD system appeared effective in not only laboratorial but also industrial S. cerevisiae strains that are diploid or polyploid. Since Pt is a safe and inexpensive chemical, ptxD could be used as a novel dominant selection marker applicable on an industrial scale.

Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p-n junctions

The development of light-emitting diodes with improved efficiency, spectral properties, compactness and integrability is important for lighting, display, optical interconnect, logic and sensor applications. Monolayer transition-metal dichalcogenides have recently emerged as interesting candidates for optoelectronic applications due to their unique optical properties. Electroluminescence has already been observed from monolayer MoS2 devices. However, the electroluminescence efficiency was low and the linewidth broad due both to the poor optical quality of the MoS2 and to ineffective contacts. Here, we report electroluminescence from lateral p-n junctions in monolayer WSe2 induced electrostatically using a thin boron nitride support as a dielectric layer with multiple metal gates beneath. This structure allows effective injection of electrons and holes, and, combined with the high optical quality of WSe2, yields bright electroluminescence with 1,000 times smaller injection current and 10 times smaller linewidth than in MoS2 (refs 17,18). Furthermore, by increasing the injection bias we can tune the electroluminescence between regimes of impurity-bound, charged and neutral excitons. This system has the required ingredients for new types of optoelectronic device, such as spin- and valley-polarized light-emitting diodes, on-chip lasers and two-dimensional electro-optic modulators.

The oxidative stress responsive transcription factor Pap1 confers DNA damage resistance on checkpoint-deficient fission yeast cells

Eukaryotic cells invoke mechanisms to promote survival when confronted with cellular stress or damage to the genome. The protein kinase Chk1 is an integral and conserved component of the DNA damage response pathway. Mutation or inhibition of Chk1 results in mitotic death when cells are exposed to DNA damage. Oxidative stress activates a pathway that results in nuclear accumulation of the bZIP transcription factor Pap1. We report the novel finding that fission yeast Pap1 confers resistance to drug- and non-drug-induced DNA damage even when the DNA damage checkpoint is compromised. Multi-copy expression of Pap1 restores growth to chk1-deficient cells exposed to camptothecin or hydroxyurea. Unexpectedly, increased Pap1 expression also promotes survival of chk1-deficient cells with mutations in genes encoding DNA ligase (cdc17) or DNA polymerase δ (cdc6), but not DNA replication initiation mutants. The ability of Pap1 to confer resistance to DNA damage was not specific to chk1 mutants, as it also improved survival of rad1- and rad9-deficient cells in the presence of CPT. To confer resistance to DNA damage Pap1 must localize to the nucleus and be transcriptionally active.

Development of a portable bridge-to-decision blood pump

We are developing an axial-flow pump with a cylindrical-impeller without airfoils. In the mock experiments of HA02 model a pressure of 13.3 kPa was obtained at a rotational speed of 12500 rpm and flow of 5L/min. The obtained pressure with HA02 was almost double than an airfoil-type impeller. The 2D analysis of hydrodynamic bearings for the pump revealed that a section with 3 or more arcs is stable with respect to angular position, and a minimum bearing gap of 100 µm can be attained at a design bearing gap of 150 µm and at a groove depth of 100 µm.

Tunable and highly reproducible surface-enhanced Raman scattering substrates made from large-scale nanoparticle arrays based on periodically poled LiNbO3 templates

This work describes novel surface-enhanced Raman scattering (SERS) substrates based on ferroelectric periodically poled LiNbO₃ templates. The templates comprise silver nanoparticles (AgNPs), the size and position of which are tailored by ferroelectric lithography. The substrate has uniform and large sampling areas that show SERS effective with excellent signal reproducibility, for which the fabrication protocol is advantageous in its simplicity. We demonstrate ferroelectric-based SERS substrates with particle sizes ranging from 30 to 70 nm and present tunable SERS effect from Raman active 4-mercaptopyridine molecules attached to AgNPs when excited by a laser source at 514 nm.

Host-dependent control of early regulatory and effector T-cell differentiation underlies the genetic susceptibility of RAG2-deficient mouse strains to transfer colitis

De novo differentiation of CD4(+)Foxp3(+) regulatory T cells (induced (i) Tregs) occurs preferentially in the gut-associated lymphoid tissues (GALT). We addressed the contribution of background genetic factors in affecting the balance of iTreg, T helper type 1 (Th1), and Th17 cell differentiation in GALT in vivo following the transfer of naive CD4(+)CD45RB(high) T cells to strains of RAG2-deficient mice with differential susceptibility to inflammatory colitis. iTregs represented up to 5% of CD4(+) T cells in mesenteric lymph nodes of less-susceptible C57BL/6 RAG2(-/-) mice compared with <1% in highly susceptible C57BL/10 RAG2(-/-) mice 2 weeks following T-cell transfer before the onset of colitis. Early Treg induction was correlated inversely with effector cell expansion and the severity of colitis development, was controlled primarily by host and not T-cell-dependent factors, and was strongly associated with interleukin-12 (IL-12)/23 production by host CD11c(+)CD103(+) dendritic cells. These data highlight the importance of genetic factors regulating IL-12/23 production in controlling the balance between iTreg differentiation and effector-pathogenic CD4(+) T-cell expansion in lymphopenic mice and indicate a direct role for iTregs in the regulation of colonic inflammation in vivo.

The type-2 N-end rule peptide recognition activity of Ubr11 ubiquitin ligase is required for the expression of peptide transporters

The Ubr1-like canonical N-recognins, widely conserved ubiquitin ligases in eukaryotes, play a role in the N-end rule pathway-mediated degradation of substrates harboring basic (type-1) or bulky hydrophobic (type-2) amino acids at the N-terminus. In this study, the roles of conserved domains were studied in the Schizosaccharomyces pombe Ubr11 protein. Mutations in the UBR box and the autoinhibitory domain blocked degradation of both type-1 and type-2 substrates, expression of peptide transporter genes, and the uptake of oligopeptides. An N-domain mutant was normal for the type-1-related function, but nevertheless failed to express peptide transporters. These data suggest the importance of the type-2-related activity of Ubr11 for its in vivo function.

Intestinal regeneration, residual function and immunological priming following rescue therapy after rat small bowel transplantation

Clinical evidence suggests that recurrent acute cellular rejection (ACR) may trigger chronic rejection and impair outcome after intestinal transplantation. To test this hypothesis and clarify underlying molecular mechanisms, orthotopic/allogenic intestinal transplantation was performed in rats. ACR was allowed to occur in a MHC-disparate combination (BN-LEW) and two rescue strategies (FK506monotherapy vs. FK506+infliximab) were tested against continuous immunosuppression without ACR, with observation for 7/14 and 21 days after transplantation. Both, FK506 and FK506+infliximab rescue therapy reversed ACR and resulted in improved histology and less cellular infiltration. Proinflammatory cytokines and chemotactic mediators in the muscle layer were significantly reduced in FK506 treated groups. Increased levels of CD4, FOXP3 and IL-17 (mRNA) were observed with infliximab. Contractile function improved significantly after FK506 rescue therapy, with a slight benefit from additional infliximab, but did not reach nontransplanted controls. Fibrosis onset was detected in both rescue groups by Sirius-Red staining with concomitant increase of the fibrogenic mediator VEGF. Recovery from ACR could be attained by both rescue therapy regimens, progressing steadily after initiation of immunosuppression. Reversal of ACR, however, resulted in early stage graft fibrosis. Additional infliximab treatment may enhance physiological recovery of the muscle layer and enteric nervous system independent of inflammatory reactions.

Essential role of Ubr11, but not Ubr1, as an N-end rule ubiquitin ligase in Schizosaccharomyces pombe

The N-end rule pathway degrades proteins bearing a destabilization-inducing amino acid at the N-terminus. In this proteolytic system, Ubr ubiquitin ligases recognize and ubiquitylate substrates intended for degradation. Schizosaccharomyces pombe has two similar Ubr proteins, Ubr1 and Ubr11. Both proteins have unique roles in various cellular processes, although the ubr1∆ strain shows more severe defects. However, their involvement in the N-end rule pathway is unclear, and even the N-end rule pathway-dependent proteolytic activity has not been demonstrated in Sz. pombe. Here, we show that: (a) Sz. pombe has the N-end rule pathway in which only Ubr11, but not Ubr1, is responsible; and (b) the C-terminal fragment of the meiotic cohesin Rec8 (denoted as Rec8c) generated by separase-mediated cleavage is an endogenous substrate of the N-end rule pathway. Forced overexpression of stable Rec8c was deleterious in mitosis and caused a loss of the mini-chromosome. In unperturbed mitosis without overexpression, the rate of mini-chromosome loss was five-fold higher in the ubr11∆ strain. Since Rec8 is normally produced in meiosis, we examined whether meiosis and sporulation were affected in the ubr11∆ strain. In unperturbed meiosis, chromosome segregation occurred almost normally and viable spores were produced in the ubr11∆ cells, irrespective of the presence of undegraded endogenous Rec8c peptides.

Correlation between reduced p21(WAF1/CIP1) expression and abnormal p53 expression in esophageal carcinomas

p21(WAF1/CIP1) is a potent inhibitor of various cyclin-dependent kinases, the expression of which is transcriptionally regulated by tumor suppressor gene product p53. We immunohistochemically examined the expression of p53 and p21(WAF1/CIP1) in 61 esophageal squamous cell carcinomas. p53 protein was expressed in 37 (61%) of 61 carcinomas. p21(WAF1/CIP1) was consistently expressed in the normal stratified esophageal mucosa. In the carcinomas, the expression of p21(WAF1/CIP1) protein was markedly reduced or not expressed in 33 (54%) cases. Clinicopathologic analyses revealed that no significant correlation exists either between p53-positive and -negative cases or between p21(WAF1)/(CIP1)-positive and -negative cases. Twenty-four cases were p53-positive/p21(WAF1/CIP1) negative, 15 were p53-negative/p21(WAF1/CIP1)-positive, 13 were positive for both and 9 were negative for both, and these findings thus showed an inverse correlation of the positivity between p53 and p21(WAF1/CIP1) (p<0.05). Furthermore, of the 13 cases with positive staining for both, the distribution of the expression was mutually exclusive in 6 cases and coincidental in the remaining 7 cases. These findings showed the p53-dependent expression of p21(WAF1/CIP1) was observed in esophageal squamous cell carcinomas, while the lack of an absolute correlation between abnormal p53 expression and p21(WAF1/CIP1) expression suggested that the p53-independent expression of p21(WAF1/CIP1) might also occur in some portions of the esophageal squamous carcinomas, suggesting that the molecular mechanisms of esophageal carcinogenesis appear to be complicated.

Selective high expression of protein phosphatase pp1-alpha messenger-RNA in rat poorly differentiated ascites hepatomas

We have examined the mRNA levels for the catalytic subunits of three phosphoseryl/phosphothreonyl protein phosphatases PP1alpha, PP2Aalpha and PP2C by Northern blot analysis in the three primary hepatomas and the three poorly differentiated ascites hepatomas. The mRNA levels were compared with those in regenerating rat livers. In regenerating rat livers, the mRNA levels of PP1alpha, PP2Aalpha and PP2C at 24 h after partial hepatectomy were elevated 5, 14 and 10 times as compared to those of the control livers. But in the three primary hepatomas induced by 3'-methyl-4-dimethyl-aminoazobenzene(3'-Me-DAB), 2-acetylaminofluorene(2-AAF), and induced by the Solt-Farber model, the mRNA levels of PP1alpha, PP2Aalpha and PP2C were almost the same as those of the control livers. On the other hand, in the three poorly differentiated ascites hepatomas, AH13, AH66F and AH130, PP1alpha mRNA levels were 10 times higher than that of the control livers. In these ascites hepatomas, PP2Aalpha mRNA levels were distinctively lower than that of the control livers. PP2C mRNA levels were the same in AH13 and lower in AH66F and AH130 compared to the controls. From these results, it was demonstrated that PP1alpha mRNA levels were selectively increased in poorly differentiated ascites hepatoma cells.

Nano-pulverization of poorly water soluble compounds with low melting points by a rotation/revolution pulverizer

We report a method for pulverizing poorly water soluble compounds with low melting points to nanoparticles without producing an amorphous phase using a rotation/revolution pulverizer. Fenofibrate, flurbiprofen, and probucol were used as crystalline model compounds. They were suspended in a methylcellulose aqueous solution and pulverized with zirconia balls by the rotation/revolution pulverizer. Beeswax, an amorphous compound, was also examined to investigate whether nano-pulverization of a compound with a low melting point was possible. Beeswax was suspended in ethyl alcohol cooled with liquid nitrogen and pulverized with zirconia balls by the rotation/revolution pulverizer. By optimizing the pulverization parameters, nanoparticles (D50 < 0.15 microm) of the crystalline compounds were obtained with narrow particle size distributions at a rotation/revolution speed of 1000 rpm and a rotation/revolution ratio of 1.0 when the vessel was 0 degrees C. Amorphous fenofibrate and flurbiprofen were not detected by differential scanning calorimetry or powder X-ray diffraction, whereas small amounts of amorphous probucol were detected. Beeswax was pulverized to nanoparticles (D50 = 0.14 microm) with ethyl alcohol cooled with liquid nitrogen. Fine nanoparticles of these poorly water soluble compounds with low melting points were obtained by controlling the rotation/revolution speed and reducing the vessel temperature.

Case of anti-glomerular basement membrane antibody-induced glomerulonephritis with cytomegalovirus-induced thrombotic microangiopathy

Although the involvement of cytomegalovirus (CMV) infections in the development of thrombotic microangiopathy (TMA) in HIV patients and transplant recipients has been reported, it is still controversial whether CMV itself can cause TMA. We report herein a rare case with rapid improvement of TMA by ganciclovir treatment in a patient who is neither HIV-positive nor a transplant recipient, suggesting a pathogenic role for CMV in TMA.

Multifunctional protein-enabled patterning on arrayed ferroelectric materials

This study demonstrates a biological route to programming well-defined protein-inorganic interfaces with an arrayed geometry via modular peptide tag technology. To illustrate this concept, we designed a model multifunctional fusion protein, which simultaneously displays a maltose-binding protein (MBP), a green fluorescence protein (GFPuv) and an inorganic-binding peptide (AgBP2C). The fused combinatorially selected AgBP2C tag controls and site-directs the multifunctional fusion protein to immobilize on silver nanoparticle arrays that are fabricated on specific domain surfaces of ferroelectric LiNbO(3) via photochemical deposition and in situ synthesis. Our combined peptide-assisted biological and ferroelectric lithography approach offers modular design and versatility in tailoring surface reactivity for fabrication of nanoscale devices in environmentally benign conditions.