Measurements of neutrino oscillation parameters from the T2K experiment using 3.6×1021 protons on target

The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7 ( 16.3 ) × 10 20 protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7 × 10 20 POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin 2 θ 13 and the impact of priors on the δ CP measurement. Both analyses prefer the normal mass ordering and upper octant of sin 2 θ 23 with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin 2 θ 13 from reactors, sin 2 θ 23 = 0 . 561 - 0.032 + 0.021 using Feldman-Cousins corrected intervals, and Δ m 32 2 = 2 . 494 - 0.058 + 0.041 × 10 - 3 eV 2 using constant Δ χ 2 intervals. The CP-violating phase is constrained to δ CP = - 1 . 97 - 0.70 + 0.97 using Feldman-Cousins corrected intervals, and δ CP = 0 , π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2 σ credible level using a flat prior in δ CP , and just below 2 σ using a flat prior in sin δ CP . When the external constraint on sin 2 θ 13 is removed, sin 2 θ 13 = 28 . 0 - 6.5 + 2.8 × 10 - 3 , in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.

Combination therapy strategies for improving PD-1 blockade efficacy: a new era in cancer immunotherapy

Programmed death 1 (PD-1) is an immune checkpoint molecule that negatively regulates T-cell immune function through the interaction with its ligand PD-L1. Blockage of this interaction unleashes the immune system to fight cancer. Immunotherapy using PD-1 blockade has led to a paradigm shift in the field of cancer drug discovery, owing to its durable effect against a wide variety of cancers with limited adverse effects. A brief history and development of PD-1 blockade, from the initial discovery of PD-1 to the recent clinical output of this therapy, have been summarized here. Despite its tremendous clinical success rate over other cancer treatments, PD-1 blockade has its own pitfall; a significant fraction of patients remains unresponsive to this therapy. The key to improve the PD-1 blockade therapy is the development of combination therapies. As this approach has garnered worldwide interest, here, we have summarized the recent trends in the development of PD-1 blockade-based combination therapies and the ongoing clinical trials. These include combinations with checkpoint inhibitors, radiation therapy, chemotherapy and several other existing cancer treatments. Importantly, FDA has approved PD-1 blockade agent to be used in combination with either CTLA-4 blockade or chemotherapy. Responsiveness to the PD-1 blockade therapy is affected by tumour and immune system-related factors. The role of the immune system, especially T cells, in determining the responsiveness has been poorly studied compared with those factors related to the tumour side. Energy metabolism has emerged as one of the important regulatory mechanisms for the function and differentiation of T cells. We have documented here the recent results regarding the augmentation of PD-1 blockade efficacy by augmenting mitochondrial energy metabolism of T cell.

Ischemic Preconditioning Enhances Muscle Endurance during Sustained Isometric Exercise

Ischemic preconditioning (IPC) enhances whole-body exercise endurance. However, it is poorly understood whether the beneficial effects originate from systemic (e. g., cardiovascular system) or peripheral (e. g., skeletal muscle) adaptations. The present study examined the effects of IPC on local muscle endurance during fatiguing isometric exercise. 12 male subjects performed sustained isometric unilateral knee-extension exercise at 20% of maximal voluntary contraction until failure. Prior to the exercise, subjects completed IPC or control (CON) treatments. During exercise trial, electromyography activity and near-infrared spectroscopy-derived deoxygenation in skeletal muscle were continuously recorded. Endurance time to task failure was significantly longer in IPC than in CON (mean±SE; 233±9 vs. 198±9 s, P<0.001). Quadriceps electromyography activity was not significantly different between IPC and CON. In contrast, deoxygenation dynamics in the quadriceps vastus lateralis muscle was significantly faster in IPC than in CON (27.1±3.4 vs. 35.0±3.6 s, P<0.01). The present study found that IPC can enhance muscular endurance during fatiguing isometric exercise. Moreover, IPC accelerated muscle deoxygenation dynamics during the exercise. Therefore, we suggest that the origin of beneficial effects of IPC on exercise performance may be the enhanced mitochondrial metabolism in skeletal muscle.

High-rate quantum key distribution over 100 km using ultra-low-noise, 2-GHz sinusoidally gated InGaAs/InP avalanche photodiodes

We have demonstrated quantum key distribution (QKD) over 100 km using single-photon detectors based on InGaAs/InP avalanche photodiodes (APDs). We implemented the differential phase shift QKD (DPS-QKD) protocol with electrically cooled and 2-GHz sinusoidally gated APDs. The single-photon detector has a dark count probability of 2.8 × 10(-8) (55 counts per second) with a detection efficiency of 6 %, which enabled us to achieve 24 kbit/s secure key rate over 100 km of optical fiber. The DPS-QKD system offers better performances in a practical way than those achieved using superconducting single-photon detectors. Moreover, the distance that secure keys against the general individual attacks can be distributed has been extended to 160 km.

Field test of quantum key distribution in the Tokyo QKD Network

A secure communication network with quantum key distribution in a metropolitan area is reported. Six different QKD systems are integrated into a mesh-type network. GHz-clocked QKD links enable us to demonstrate the world-first secure TV conferencing over a distance of 45km. The network includes a commercial QKD product for long-term stable operation, and application interface to secure mobile phones. Detection of an eavesdropper, rerouting into a secure path, and key relay via trusted nodes are demonstrated in this network.

Structures of defective P transposable elements prevalent in natural Q and Q-derived M strains of Drosophila melanogaster

Several DNA sequences with homology to the complete 2.9-kilobase (kb) P element from a P strain in the United States were isolated and characterized from two Drosophila melanogaster strains collected on Chichi Jima, an island 1000 km south of Tokyo. Except for a missing central region and trivial unsequenced regions of 38 base pairs, the 2.1-kb element isolated from a Q strain had the same DNA sequence as that of the complete P element. Seven other elements cloned from genomic DNAs of the Q strain and a Q-derived M strain all possessed the same restriction sites as those of the 2.9-kb P element except for one deleted region in each element. The finding of sequence conservation in P elements have had a common ancestor relatively recently. Thus, it is suggested that the P element family was a recent invader of the species. By contrast, no complete P element was found in these Japanese strains so far as surveyed, indicating the possibility that P elements in the Chichi Jima population are almost all defective. The implication of this possibility is discussed in relation to the uniqueness of the population on Chichi Jima where Q strains predominate and no P strains have yet been found.

AID-induced T-lymphoma or B-leukemia/lymphoma in a mouse BMT model

Activation-induced cytidine deaminase (AID) diversifies immunoglobulin through somatic hypermutation (SHM) and class-switch recombination (CSR). AID-transgenic mice develop T-lymphoma, indicating that constitutive expression of AID leads to tumorigenesis. Here, we transplanted mouse bone marrow cells transduced with AID. Twenty-four of the 32 recipient mice developed T-lymphoma 2-4 months after the transplantation. Surprisingly, unlike AID-transgenic mice, seven recipients developed B-leukemia/lymphoma with longer latencies. None of the mice suffered from myeloid leukemia. When we used nude mice as recipients, they developed only B-leukemia/lymphoma, presumably due to lack of thymus. Analysis of AID mutants suggested that an intact form with SHM activity is required for maximum ability of AID to induce lymphoma. Except for a K-ras active mutant in one case, specific mutations could not be identified in T-lymphoma; however, Notch1 was constitutively activated in most cases. Importantly, truncations of Ebf1 or Pax5 were observed in B-leukemia/lymphoma. In conclusion, this is the first report on the potential of AID overexpression to promote B-cell lymphomagenesis in a mouse model. Aberrant expression of AID in bone marrow cells induced leukemia/lymphoma in a cell-lineage-dependent manner, mainly through its function as a mutator.

Efficient entanglement distribution over 200 kilometers

Here we report the first demonstration of entanglement distribution over a record distance of 200 km which is of sufficient fidelity to realize secure communication. In contrast to previous entanglement distribution schemes, we use detection elements based on practical avalanche photodiodes (APDs) operating in a self-differencing mode. These APDs are low-cost, compact and easy to operate requiring only electrical cooling to achieve high single photon detection efficiency. The self-differencing APDs in combination with a reliable parametric down-conversion source demonstrate that entanglement distribution over ultra-long distances has become both possible and practical. Consequently the outlook is extremely promising for real world entanglement-based communication between distantly separated parties.

Comparison of three commercially available prescription diet regimens on short-term post-prandial serum glucose and insulin concentrations in healthy cats

Dietary therapy is an important treatment component for diabetes mellitus (DM). In this study, the impact of three different commercially available diet regiments (1 general use and 2 aimed for treating obesity and DM) on short-term post-prandial serum glucose and insulin concentrations of five healthy cats to better understand what impact each of these diets may have for diabetic cats. The diet regiments used in this study were as follows: C/D dry (General Use- Low protein, High fat, High carbohydrate, and Low fiber), M/D dry (DM- High protein, High fat, Low carbohydrate, and High Fiber), and W/D dry (DM- Low Protein, Low Fat, High Carbohydrate, and High Fiber). No significant difference in post-prandial serum glucose levels were observed with the C/D (84.6 +/- 1.5 mg/dl) and W/D (83.8 +/- 1.4 mg/dl) dry diets when compared to pre-prandial fasting levels (83.9 +/- 1.4 mg/dl). However, a significant reduction was observed with the M/D diet (78.9 +/- 0.8 mg/dl) which had 50-60% less carbohydrates than either C/D or W/D diet. Unlike what was observed with post-prandial glucose levels, an interesting pattern emerged with post-prandial insulin levels, which were increasing with W/D, C/D, and M/D diets in that order (1.1 +/- 0.2, 1.7 +/- 0.2, and 2.3 +/- 0.2 ng/ml respectively). Most surprising, though, was the fact that the W/D diet did not seem to stimulate insulin secretion as compared to pre-prandial levels (1.1 +/- 0.1 ng/ml) in healthy cats. Interestingly, the W/D diet had high levels of carbohydrate and low levels of protein. Coincidentally, the only diet (M/D) which had a significant reduction in post-prandial glucose also showed the highest increase in post-prandial insulin in healthy cats. Therefore, dietary amounts of carbohydrate, fat, protein and fiber can all have an individual impact on post-prandial glycemia and subsequent insulin requirement levels. Just as concepts regarding dietary management of people with DM are evolving, investigators are reassessing what constitutes the ideal diet for the diabetic feline. As such, having a better understanding for each dietary component, may lead us to better understand how we can synergize certain dietary components to aid in DM management.

Long-distance entanglement-based quantum key distribution over optical fiber

We report the first entanglement-based quantum key distribution (QKD) experiment over a 100-km optical fiber. We used superconducting single photon detectors based on NbN nanowires that provide high-speed single photon detection for the 1.5-mum telecom band, an efficient entangled photon pair source that consists of a fiber coupled periodically poled lithium niobate waveguide and ultra low loss filters, and planar lightwave circuit Mach-Zehnder interferometers (MZIs) with ultra stable operation. These characteristics enabled us to perform an entanglement-based QKD experiment over a 100-km optical fiber. In the experiment, which lasted approximately 8 hours, we successfully generated a 16 kbit sifted key with a quantum bit error rate of 6.9 % at a rate of 0.59 bits per second, from which we were able to distill a 3.9 kbit secure key.

Differential-phase-shift quantum secret sharing

A quantum secret sharing (QSS) protocol based on a differential-phase-shift scheme is proposed, which quantum mechanically provides a full secret key to one party and partial keys to two other parties. A weak coherent pulse train is utilized instead of individual photons as in conventional schemes. Compared with previous QSS protocols, the present one features a simple setup, is suitable for fiber transmission, and offers the possibility for a high key creation rate. An experiment is also carried out to demonstrate the operation.

Efficient and low-noise single-photon detection in 1550 nm communication band by frequency upconversion in periodically poled LiNbO3 waveguides

We demonstrate 1500 nm band single-photon detection with low dark-count noise and a potentially high efficiency, which may allow long distance and high-bit-rate quantum key distribution. By developing frequency upconversion devices based on periodically poled lithium niobate waveguides, which are specifically designed to use a pump wavelength longer than that of communication-band photons, we completely eliminate the dark-count noise caused by parasitic nonlinear processes in the waveguide. We observed an internal conversion efficiency as high as 40% and demonstrated scaling down to the single photon level while maintaining a background dark-count rate of 10(2)s(-1).

Field trial of differential-phase-shift quantum key distribution using polarization independent frequency up-conversion detectors

We report a field trial of differential phase shift quantum key distribution (QKD) using polarization independent frequency up-conversion detectors. A frequency up-conversion detector is a promising device for achieving a high key generation rate when combined with a high clock rate QKD system. However, its polarization dependence prevents it from being applied to practical QKD systems. In this paper, we employ a modified polarization diversity configuration to eliminate the polarization dependence. Applying this method, we performed a long-term stability test using a 17.6-km installed fiber. We successfully demonstrated stable operation for 6 hours and achieved a sifted key generation rate of 120 kbps and an average quantum bit error rate of 3.14 %. The sifted key generation rate was not the estimated value but the effective value, which means that the sifted key was continuously generated at a rate of 120 kbps for 6 hours.

Long-distance distribution of time-bin entangled photon pairs over 100 km using frequency up-conversion detectors

We report an experimental demonstration of the distribution of time-bin entangled photon pairs over 100 km of optical fiber. In our experiment, 1.5-mum non-degenerated time-bin entangled photon pairs were generated with a periodically poled lithium niobate (PPLN) waveguide by using the parametric down conversion process. Combining this approach with ultra-low-loss filters to eliminate the pump light and separate signal and idler photons, we obtained an efficient entangled photon pair source. To detect the photons, we used single-photon detectors based on frequency up-conversion. These detectors operated in a non-gated mode so that we could use a pulse stream of time correlated entangled photon pairs at a high repetition frequency (1 GHz). Using these elements, we distributed time-bin entangled photon pairs over 100 km of dispersion shifted fiber and performed a two-photon interference experiment. We obtained a coincidence fringe of 81.6% visibility without subtracting any background noise, such as accidental coincidence or dark count, which was good enough to violate Bell's inequality. Thus, we successfully distributed time-bin entangled photon pairs over 100 km.

Expression of activation-induced cytidine deaminase in human hepatocytes via NF-kappaB signaling

Activation-induced cytidine deaminase (AID) is involved in somatic DNA alterations of the immunoglobulin gene for amplification of immune diversity. The fact that constitutive expression of AID in mice causes tumors in various organs, including lymphoid tissues and lungs, suggests the important role of the aberrant editing activity of AID on various tumor-related genes for carcinogenesis. AID expression, however, is restricted to activated B cells under physiological conditions. We demonstrate here that ectopic AID expression is induced in response to tumor necrosis factor-alpha stimulation in cultured human hepatocytes. The proinflammatory cytokine-mediated expression of AID is achieved by IkappaB kinase-dependent nuclear factor (NF)-kappaB signaling pathways. Hepatitis C virus, one of the leading causes of hepatocellular carcinoma (HCC), enhanced AID expression via NF-kappaB activation through expression of viral core protein. The aberrant expression of AID in hepatoma-derived cells resulted in accumulation of genetic alterations in the c-myc and pim1 genes, suggesting that inappropriate expression of AID acts as a DNA mutator that enhances the genetic susceptibility to mutagenesis in human hepatocytes. Our current findings indicate that the inappropriate expression of AID is induced by proinflammatory cytokine stimulation and may provide the link between hepatic inflammation and the development of HCC.

Generation of energy-time entangled photon pairs in 1.5-mum band with periodically poled lithium niobate waveguide

We report the generation of 1.5-mm-band energy-time entangled photon pairs using a periodically poled lithium niobate (PPLN) waveguide. We performed a two-photon interference experiment and obtained coincidence fringes with 77.3% visibilities without subtracting accidental coincidences.

Subtype IV of the BK polyomavirus is prevalent in East Asia

BK polyomavirus (BKV) is ubiquitous in human populations, infecting children asymptomatically and then persisting in the kidney. Using either serological or genotyping methods, BKV isolates have been classified into four subtypes (I-IV), with subtype I mainly detected in all countries studied so far. To elucidate the subtype of BKV prevalent in East Asia, we examined BKV-positive urine samples collected from immunocompetent elderly patients in Mongolia, Northeast China, Northwest China, Southeast China, Southwest China, Vietnam and Japan. The 287-bp typing region of the viral genome in each of these samples was PCR-amplified and sequenced, and a phylogenetic tree was constructed. According to the tree, BKV isolates in East Asia were unambiguously classified into subtype I or IV (subtypes II and III were not detected). In Japan, subtype I was mainly detected and subtype IV was rare, whereas in the other regions subtype IV was detected frequently, at rates ranging from 24 to 100%. Thus, East Asia (excluding Japan) is a region in which subtype-IV BKV is prevalent, a finding that requires the view of the geographic distribution of BKV subtypes to be revised. Furthermore, we present evidence that the immunological states of urine donors do not affect the pattern of BKV subtypes.

Differential-phase-shift quantum key distribution experiment with a planar light-wave circuit Mach-Zehnder interferometer

A differential-phase-shift quantum key distribution experiment was carried out with a planar light-wave circuit (PLC) Mach-Zehnder interferometer. This scheme has two advantages: it requires no polarization control and has a high repetition frequency, provided that a stable interferometer is available. Stable polarization-insensitive operation was achieved with an interferometer fabricated by PLC technology. Raw key creation at a rate of 3076 bits/s with a 5.0% quantum bit-error rate was achieved over 20 km of fiber. The stability of the PLC interferometer was examined.

Birth of offspring following transplantation of cryopreserved immature testicular pieces and in-vitro microinsemination

BACKGROUND

Fertility protection is an urgent clinical problem for prepubertal male oncology patients who undergo either chemotherapy or radiotherapy. As these patients do not have mature sperm to be frozen, there is as yet no effective method to preserve their fertility.

METHODS AND RESULTS

Single pieces of immature mouse (1.5 x 1.5 x 1.5 mm) or rabbit (2.0 x 2.0 x approximately 3.0 mm) testis were cryopreserved, thawed and transplanted into mouse testes. Histological techniques were used to determine the presence of spermatogenesis, which was restored in both mouse and rabbit testicular pieces, and led to the production of mature sperm after both cryopreservation and syngeneic or xenogeneic transplantation into mouse testes. Using sperm developed in the frozen-thawed transplants, mouse offspring were born after in-vitro microinsemination. Furthermore, rabbit offspring were obtained using rabbit sperm that developed in fresh transplants in a xenogeneic surrogate mouse.

CONCLUSIONS

This approach of 'testicular tissue banking' is a promising technique for the preservation of fertility in prepubertal male oncology patients. Xenogeneic transplantation into immunodeficient mice may provide a system for studying spermatogenic failure in infertile men.

Asian domains of four major genotypes of JC virus, Af2, B1-b, CY and SC

JC virus (JCV) strains worldwide can be classified into various genotypes based on DNA sequence variations. To define the domains of the four major JCV genotypes in Asia, we collected urine samples at six unstudied sites: three in southeastern Asia, two in the central highlands and one in central Asia. DNA was extracted from urine samples, and used to amplify a 610-bp region of the viral genome. For each geographical site, we determined 16 to 31 sequences, from which a phylogenetic tree was constructed to unambiguously classify detected JCV isolates into distinct genotypes. From JCV genotype profiles at the sites studied here and elsewhere, the following conclusions were drawn. Although Af2 is the major genotype in Africa, this genotype also occurs in western and central Asia. B1-b mainly occurs in western and central Asia, including the central highlands. CY occurs in northeastern Asia with the southern boundary between China and southeast Asian countries. Although SC predominates in southeastern Asia, it also occurs in northern and central Asia at lower frequencies. In addition, a few minor JCV genotypes (B1-a, B2 and B3) occur at many sites. We discuss here the anthropological and medical significance of the present findings.

Variable deletion and duplication at recombination junction ends: implication for staggered double-strand cleavage in class-switch recombination

Immunoglobulin class-switch recombination (CSR) gives rise to looped-out circular DNA of a cleaved S segment, which is lost eventually after cell divisions. To understand the molecular mechanism of S region cleavage during CSR, we constructed artificial CSR substrates in which inversion-type CSR takes place to retain the cleaved S segment. Sequencing analyses of recombinant clones of these substrates revealed that varying degrees of deletions and duplications exist at CSR breakpoints, suggesting the involvement of staggered cleavage of the S region in CSR. In addition, mutations frequently found near junctions showed a similar profile of base replacement to Ig somatic hypermutation. These findings suggest that single-strand tails of staggered cleavage may be repaired by error-prone DNA synthesis.

PD-1 immunoreceptor inhibits B cell receptor-mediated signaling by recruiting src homology 2-domain-containing tyrosine phosphatase 2 to phosphotyrosine

PD-1 is an immunoreceptor that belongs to the immunoglobulin (Ig) superfamily and contains two tyrosine residues in the cytoplasmic region. Studies on PD-1-deficient mice have shown that PD-1 plays critical roles in establishment and/or maintenance of peripheral tolerance, but the mode of action is totally unknown. To study the molecular mechanism for negative regulation of lymphocytes through the PD-1 receptor, we generated chimeric molecules composed of the IgG Fc receptor type IIB (Fc gamma RIIB) extracellular region and the PD-1 cytoplasmic region and expressed them in a B lymphoma cell line, IIA1.6. Coligation of the cytoplasmic region of PD-1 with the B cell receptor (BCR) in IIA1.6 transformants inhibited BCR-mediated growth retardation, Ca(2+) mobilization, and tyrosine phosphorylation of effector molecules, including Ig beta, Syk, phospholipase C-gamma 2 (PLC gamma 2), and ERK1/2, whereas phosphorylation of Lyn and Dok was not affected. Mutagenesis studies indicated that these inhibitory effects do not require the N-terminal tyrosine in the immunoreceptor tyrosine-based inhibitory motif-like sequence, but do require the other tyrosine residue in the C-terminal tail. This tyrosine was phosphorylated and recruited src homology 2-domain-containing tyrosine phosphatase 2 (SHP-2) on coligation of PD-1 with BCR. These results show that PD-1 can inhibit BCR signaling by recruiting SHP-2 to its phosphotyrosine and dephosphorylating key signal transducers of BCR signaling.

Life-cycle toxicity of 4-nonylphenol to medaka (Oryzias latipes)

We studied the chronic effects of 4-nonylphenol (4-NP) on reproductive status of medaka (Oryzias latipes) over two generations of continuous exposure. The exposure study of the parental (F0) medaka was begun on embryos within 24 h postfertilization and continued with monitoring through embryological development, hatching, posthatch survival, growth, sexual differentiation, and reproduction under flow-through exposures to mean measured 4-NP concentrations of 4.2, 8.2, 17.7, 51.5, and 183 microg/L for up to 104 d. Eggs spawned from the F0 fish at 102 and 103 d posthatch were also examined for hatchability, survival after hatching, growth, and sexual differentiation until 60 d posthatch. The 183-microg/L treatment significantly reduced the embryo survival and swim-up success of the F0 fish. The cumulative mortality after swim-up of the F0 fish exposed to 17.7 and 51.5 microg/L were significantly higher than the control mortality. No concentration-related effect of 4-NP was observed on the growth of surviving F0 fish at 60 d posthatch. However, the sex ratio estimated from the appearance of their secondary sex characteristics was skewed toward female in the 51.5-microg/L treatment. Additionally, gonadal histology showed that 20% of the fish in the 17.7-microg/L treatment and 40% in the 51.5-microg/L treatment had testis-ova, indicating that 4-NP affects the gonadal development and survival of medaka at similar concentrations in juveniles. The sex ratio of the F0 fish in the 51.5-microg/L treatment was completely skewed toward female; subsequently, the effects on fecundity and fertility in this generation were monitored at mean measured concentrations of 4.2, 8.2, and 17.7 microg/L from 71 to 103 d posthatch. Fecundity was unaffected by any of the treatments examined. The mean fertility in the 17.7-microg/L treatment was reduced to 76% of that in the controls, although no statistically significant differences were determined. Overall, these results indicate that the lowest-observed-effect concentration (LOEC) and no-observed-effect concentration (NOEC) of 4-NP through the life cycle of the F0 medaka were 17.7 and 8.2 microg/L, respectively. In the F1 medaka, no significant effects were observed on hatching success, posthatch mortality, or growth, but sexual differentiation at 60 d posthatch was affected. Induction of testis-ova in the gonads of the F1 fish was observed in both the 8.2- and the 17.7-microg/L concentrations. The results indicate that 4-NP can have significant effects on reproductive potential of medaka at concentrations as low as 17.7 microg/L.

The IL-7 receptor controls the accessibility of the TCRgamma locus by Stat5 and histone acetylation

The IL-7 receptor (IL-7R) plays critical roles in expansion and V(D)J recombination during lymphocyte development. Here we demonstrate that cytokine stimulation rapidly recruits Stat5 and transcriptional coactivators to the Jgamma germline promoter and induces histone acetylation, germline transcription, and accessibility in Ba/F3 cells. We also show that histone acetylation of the TCRgamma locus is significantly reduced in IL-7R-deficient thymocytes and that the introduction of active Stat5 restores the histone acetylation and accessibility of the locus. Furthermore, treatment with histone deacetylase inhibitor recovers the histone acetylation and accessibility in IL-7R-deficient thymocytes. Therefore, these results suggest that Stat5 may recruit the transcriptional coactivators to the Jgamma germline promoter and control the accessibility of the TCRgamma locus by histone acetylation.

A hallmark of active class switch recombination: transcripts directed by I promoters on looped-out circular DNAs

To specify when and where Ig class switch recombination (CSR) takes place, a good molecular marker closely associated with active CSR is required. CSR is accompanied by deletion of circular DNA from the Ig heavy chain locus. The circular DNA contains a DNA segment between Smu and a target S region including its I promoter, which is driven by specific cytokine stimulation before CSR. We found that the specific I promoter is still active in looped-out circular DNA and directs production of I-Cmu transcripts termed "circle transcripts." Reverse transcription-PCR demonstrated transient induction of specific circle transcripts upon CSR in a murine lymphoma cell line, CH12F3-2A, as well as spleen B cells. Production of the circle transcripts appeared to depend on expression of activation-induced cytidine deaminase (AID), an essential factor for CSR. A comparison of kinetics between circle transcripts and circular DNA showed more rapid disappearance of circle transcripts. Thus, circle transcripts may serve as a hallmark for active CSR in vitro and in vivo.

In situ class switching and differentiation to IgA-producing cells in the gut lamina propria

One of the front lines of the immune defence is the gut mucosa, where immunoglobulin- (IgA) is continuously produced to react with commensal bacteria and dietary antigens. It is generally accepted that, after antigenic stimulation in the Peyer's patches, IgA+ lymphoblasts (B220+IgA+) migrate through the lymph and blood circulation, and eventually home to the lamina propria of the intestine. Mice that lack activation-induced cytidine deaminase (AID) are defective in class switch recombination (CSR) and somatic hypermutation. CSR changes the immunoglobulin heavy chain constant region (CH) gene being expressed from Cmu to other CH genes, resulting in a switch of the immunoglobulin isotype from IgM to IgG, IgE or IgA. AID-/- mice also secrete large amounts of immunoglobulin-mu (IgM) into faeces, and accumulate B220-IgM+ plasma cells as well as B220+IgM+ cells in the gut. Here we show that lamina propria B220+IgA+ cells have just completed CSR, as they still express both AID and transcripts from circular DNA that has been 'looped-out' during CSR. Lamina propria IgM+ B cells seem to be pre-committed to switching to IgA+ in vitro as well as in vivo. Culturing lamina propria IgM+ B cells together with lamina propria stromal cells enhances preferential switching and differentiation of B cells to IgA+ plasma cells. We conclude that IgA+ cells in the gut lamina propria are generated in situ from B220+IgM+ lymphocytes.

Human genetic defects in class-switch recombination (hyper-IgM syndromes)

Several genetic defects in class-switch recombination, leading to hyper-IgM syndromes, have been recently described in humans. Besides the well-known role of interaction between CD40-ligand and CD40, these pathological conditions definitively demonstrate the requirement of CD40-mediated NF-kappaB activation and the essential role of a newly described molecule, activation-induced cytidine deaminase (AID), in B cell terminal differentiation.

ESDN, a novel neuropilin-like membrane protein cloned from vascular cells with the longest secretory signal sequence among eukaryotes, is up-regulated after vascular injury

A novel cDNA has been isolated from primary culture of human coronary arterial cells by a signal sequence trap method, and designated ESDN (endothelial and smooth muscle cell-derived neuropilin-like molecule). ESDN is a type-I transmembrane protein with the longest cleavable secretory signal sequence among eukaryotes. ESDN contains a CUB domain and a coagulation factor V/VIII homology domain, which reminds us of the structure of neuropilins. ESDN also harbors an LCCL domain, which is shared by Limulus factor C and Coch. Mouse and rat counterparts were also identified revealing >84% amino acid identity with human ESDN. The human ESDN gene was mapped between D3S1552 and D3S1271. Northern blot analysis showed that ESDN mRNA was expressed in various tissues; particularly highly expressed in cultured vascular smooth muscle cells. The ESDN expression was up-regulated in platelet-derived growth factor-BB-stimulated vascular smooth muscle cells in vitro and neointima of the balloon-injured carotid artery in vivo. Overexpression of ESDN in 293T cells suppressed their bromodeoxyuridine uptake. In addition, ESDN protein was strongly expressed in nerve bundles in rodents. Thus, ESDN is considered to play a role in regulation of vascular cell growth and may have a wide variety of functions in other tissues including the nervous system, like neuropilins.

Differential roles of cytokine receptors in the development of epidermal gamma delta T cells

IL-7 and IL-15 play important roles in gammadelta T cell development. These receptors transmit proliferation and/or survival signals in gammadelta T cells. In addition, the IL-7R promotes recombination and transcription in the TCR gamma locus. To clarify the role of the cytokine receptors in the development of epidermal gammadelta T cells, we introduced a Vgamma3/Vdelta1 TCR transgene, derived from Thy-1+ dendritic epidermal T cells (DETC), into IL-7Ralpha-deficient mice, and we found that they partly rescued gammadelta T cells in the adult thymus but not in the spleen. Introduction of an additional Bcl-2 transgene had a minimal effect on gammadelta T cells in the adult thymus of these mice. In contrast to the adult thymus, the introduction of the Vgamma3/Vdelta1 TCR transgene into IL-7Ralpha-/- mice completely restored Vgamma3+ T cells in the fetal thymus and DETC in the adult skin. On the contrary, the same Vgamma3/Vdelta1 TCR transgene failed to rescue DETC in the skin of IL-2Rbeta-deficient mice, even with the additional Bcl-2 transgene. These results suggest that the IL-2/IL-15R, rather than the IL-7R, plays an essential role in proliferation and survival of DETC in the fetal thymus and the skin. In contrast, the IL-7R is probably essential in the induction of V-J recombination of TCRgamma genes. Thus, this study proves that IL-7R and IL-2/IL-15R serve differential functions in epidermal gammadelta T cell development.

Conservation of the biochemical mechanisms of signal transduction among mammalian Notch family members

Mouse Notch1, which plays an important role in cell fate determination in development, is proteolytically processed within its transmembrane domain by unidentified gamma-secretase-like activity that depends on presenilin. To study this proteolytic event, we established a cell-free Notch cleavage assay system using the membrane fraction of fibroblast transfectants of various Notch constructs with deletion of the extracellular portion (Notch DeltaE). The cytoplasmic portion of Notch1 DeltaE was released from the membrane upon incubation at 37 degrees C, which was inhibited by the specific gamma-secretase inhibitor, MW167, or by overexpression of dominant negative presenilin1. Likewise, other members of mouse Notch family were proteolytically cleaved in a presenilin-dependent, MW167-sensitive manner in vivo as well as in the cell-free Notch DeltaE cleavage assay system. All four members of the mouse Notch family migrated to the nucleus and activated the transcription from the promoter carrying the RBP-J consensus sequences after they were released from the membrane. These results demonstrate the conserved biochemical mechanism of signal transduction among mammalian Notch family members.

Linking class-switch recombination with somatic hypermutation

The recent discovery of a molecular link between two apparently different genetic alteration events--class-switch recombination and somatic hypermutation--has led to the idea that the recognition and cleavage of target DNA in these two events might be mediated by similar or identical molecules to those involved in RNA editing. This could mean that the complexity of mammalian genetic information may be enriched by an interplay between RNA editing and DNA modification.

Induction of germline transcription in the human TCR gamma locus by STAT5

TCR and Ig genes are assembled by V(D)J recombination during lymphocyte development. The enhancer and the germline promoter control the accessibility of each locus for the common recombinase activity. In the mouse TCRgamma locus, STAT5 proteins activated by the IL-7R interact with consensus motifs in 5' regions of Jgamma segments and induce germline transcription. To evaluate the role of STAT5 in controlling the accessibility of the TCRgamma locus, we characterized the germline transcription of human TCRgamma genes and compared it with mouse. We first demonstrated that Jgamma-Cgamma germline transcripts are induced in a cytokine-dependent human erythroleukemia cell line. STAT consensus motifs are present in 5' regions of Jgamma1.1 and Jgamma2.1 gene segments, and activated STAT5 binds to these motifs. By using a reporter assay, we showed that the Jgamma1.1 germline promoter is transactivated by STAT5 and that mutations in any of the two STAT motifs abrogate this activity. Thus, this study demonstrates that STAT5 induces germline transcription in the TCRgamma locus of both mouse and human and suggests the possibility that this mechanism may play an essential role in controlling the TCRgamma locus accessibility. In addition, STAT motifs are conserved among 5' Jgamma germline promoters, 3' enhancers, and a locus control region-like element, HsA, in both mouse and human TCRgamma loci, indicating the possibility that IL-7R/STAT5 signaling probably controls the locus-wide accessibility through these elements.

Plasma elevation of stromal cell-derived factor-1 induces mobilization of mature and immature hematopoietic progenitor and stem cells

The chemokine, stromal cell-derived factor-1 (SDF1), is produced in the bone marrow and has been shown to modulate the homing of stem cells to this site by mediating chemokinesis and chemotaxis. Therefore, it was hypothesized that elevation of SDF1 level in the peripheral circulation would result in mobilization of primitive hematopoietic stem and progenitor cells. SDF1 plasma level was increased by intravenous injection of an adenoviral vector expressing SDF1alpha (AdSDF1) into severe combined immunodeficient mice. This resulted in a 10-fold increase in leukocyte count, a 3-fold increase in platelets, and mobilization of progenitors, including colony-forming units-granulocyte-macrophage to the peripheral circulation. In addition, AdSDF1 induced mobilization of cells with stem cell potential, including colony-forming units in spleen and long-term reconstituting cells. These data demonstrate that overexpression of SDF1 in the peripheral circulation results in the mobilization of hematopoietic cells with repopulating capacity, progenitor cells, and precursor cells. These studies lay the foundation for using SDF1 to induce mobilization of hematopoietic stem and progenitor cells in in vivo studies. (Blood. 2001;97:3354-3360)

B cell tolerance and autoimmunity

Self-tolerance is induced in B cells at various maturational stages by diverse self-antigens B cell tolerance involves multiple mechanisms, ie. clonal deletion, clonal anergy, receptor editing and maturation arrest. The mechanism utilized for self-tolerance depends on both the maturational stage of B cells and the molecular nature of the self-antigens. B cell tolerance is abrogated by various mechanisms such as defects in inhibitory co-receptors, overexpression of CD19, T cell help and defects in the death receptor Fas (CD95). Since all of these molecules regulate B cell apoptosis mediated by either the antigen receptor or Fas, B cell apoptosis may play a role in the induction and maintenance of B cell tolerance. Moreover, environmental factors such as intestinal lipopolysaccharide also play a role in the breakdown of B cell tolerance.

Elevated plasma stromal cell-derived factor 1 protein level in the progression of HIV type 1 infection/AIDS

Stromal cell-derived factor 1 (SDF-1) is a unique chemokine involved in multiple organogenesis as well as in the regulation of HIV infection. Here we determined the plasma SDF-1 concentrations of 193 HIV-1-infected individuals and 154 normal Japanese volunteers by developing a highly sensitive measurement system based on time-resolved fluoroimmunoassay (SDF-1 TR-FIA). This system is also valid for the mouse model to quantitate circulating SDF-1 concentration in vivo and thereby its correlation with CXCR4 expression level on CD4(+) T cells. Interestingly, plasma SDF-1 concentrations in HIV-1-infected individuals were three times higher than those in a normal control group and plasma SDF-1 protein levels showed an inverse correlation with CD4(+) T cell count and a positive correlation with plasma HIV-1 RNA load. Notably, individuals with later stage HIV-1 infection, who maintained fewer than 200 CD4(+) T cells per cubic milliliter and more than 10,000 copies of HIV-1 RNA per milliliter, showed the highest plasma SDF-1 level among individuals at any stage of HIV-1 infection. These results suggest that endogenous SDF-1 is upregulated by HIV-1 infection, particularly in late-stage HIV-1 infection/AIDS.

PD-1: an inhibitory immunoreceptor involved in peripheral tolerance

PD-1 deficiency causes a variety of autoimmune diseases. Inhibitory signaling through the PD-1 receptor might therefore be involved in the regulation of peripheral tolerance. The constitutive expression of PD-1 ligands (PD-L1 and PD-L2) on parenchymal cells of heart, lung and kidney suggests that the PD-1-PD-L system could provide unique negative signaling to help prevent autoimmune diseases.

Histone acetylation determines the developmentally regulated accessibility for T cell receptor gamma gene recombination

Variable/diversity/joining (V[D]J) recombination of the T cell receptor (TCR) and immunoglobulin (Ig) genes is regulated by chromatin accessibility of the target locus to the recombinase in a lineage- and stage-specific manner. Histone acetylation has recently been proposed as a molecular mechanism underlying the accessibility control. Here, we investigate the role for histone acetylation in the developmentally regulated rearrangements of the mouse TCR-gamma gene, wherein predominant rearrangement is switched from Vgamma3 to Vgamma2 gene during the fetal to adult thymocyte development. Our results indicate that histone acetylation correlates with accessibility, as histone acetylation at the fetal-type Vgamma3 gene in accord with germline transcription is relatively high in fetal thymocytes, but specifically becomes low in adult thymocytes within the entirely hyperacetylated locus. Furthermore, inhibition of histone deacetylation during the development of adult bone marrow-derived thymocytes by a specific histone deacetylase inhibitor, trichostatin A, leads to elevated histone acetylation, germline transcription, cleavage, and rearrangement of the Vgamma3 gene. These data demonstrate that histone acetylation functionally determines the chromatin accessibility for V(D)J recombination in vivo and that an epigenetic modification of chromatin plays a direct role in executing a developmental switch in cell fate determination.

Palindromic but not G-rich sequences are targets of class switch recombination

In order to understand the specificity of sequences or structures recognized by a recombinase involved in class switch recombination (CSR), we examined the relative CSR efficiency of various switch sequences in artificial CSR constructs that undergo CSR in CH12F3-2 murine B lymphoma line. Since CSR recombination is not specific to switch regions of different isotypes or orientation of S sequences, we examined the efficiency of S sequences of non-mammalian species and artificial sequences which lack several characters of mammal switch sequences: chicken S(mu), Xenopus S(mu), telomere, multiple cloning site (MCS) and unrelated negative control sequence. CSR occurred in chicken S(mu) and MCS with significantly higher efficiency than the negative control. A common character of these two sequences is that they are rich in palindrome and stem-loop structures. However, telomeres, which are G-rich and repetitive but not palindromic, could not serve as switch sequences at all. The AT-rich Xenopus S(mu) sequence was inefficient but capable of CSR. CSR breakpoint distribution suggests that the cleavage may take place preferentially in the proximity of the junctions (neck) between the loop and stem in the secondary structure of the single-stranded S sequence, which can be formed by palindromic sequences. The results suggest that the secondary structure of S-region sequences which is transiently formed during transcription may be necessary for recognition by class switch recombinase.

The N- and C-terminal regions of RBP-J interact with the ankyrin repeats of Notch1 RAMIC to activate transcription

The evolutionarily-conserved DNA-binding protein RBP-J directly interacts with the RAM domain and the ankyrin (ANK) repeats of the Notch intracellular region (RAMIC), and activates transcription of downstream target genes that regulate cell differentiation. In vitro binding assays demonstrate that the truncated N- and C-terminal regions of RBP-J bind to the ANK repeats but not to the RAM domain. Using an OT11 mouse cell line, in which the RBP-J locus is disrupted, we showed that RBP-J constructs mutated in the N- and C-terminal regions were defective in their transcriptional activation induced by either RAMIC or IC (the Notch intracellular region without the RAM domain) although they had normal levels of binding activity to DNA and the RAM domain. The studies using chimeric molecules between RBP-J and its homolog RBP-L showed that the N- and C-terminal regions of RBP-J conferred the IC- as well as RAMIC-induced transactivation potential on RBP-L, which binds to the same DNA sequence as RBP-J but fails to interact with RAMIC. Taken together, these results indicate that the interactions between the N- and C-terminal regions of RBP-J and the ANK repeats of RAMIC are important for transactivation of RBP-J by RAMIC.

PD-L2 is a second ligand for PD-1 and inhibits T cell activation

Programmed death I (PD-I)-deficient mice develop a variety of autoimmune-like diseases, which suggests that this immunoinhibitory receptor plays an important role in tolerance. We identify here PD-1 ligand 2 (PD-L2) as a second ligand for PD-1 and compare the function and expression of PD-L1 and PD-L2. Engagement of PD-1 by PD-L2 dramatically inhibits T cell receptor (TCR)-mediated proliferation and cytokine production by CD4+ T cells. At low antigen concentrations, PD-L2-PD-1 interactions inhibit strong B7-CD28 signals. In contrast, at high antigen concentrations, PD-L2-PD-1 interactions reduce cytokine production but do not inhibit T cell proliferation. PD-L-PD-1 interactions lead to cell cycle arrest in G0/G1 but do not increase cell death. In addition, ligation of PD-1 + TCR leads to rapid phosphorylation of SHP-2, as compared to TCR ligation alone. PD-L expression was up-regulated on antigen-presenting cells by interferon gamma treatment and was also present on some normal tissues and tumor cell lines. Taken together, these studies show overlapping functions of PD-L1 and PD-L2 and indicate a key role for the PD-L-PD-1 pathway in regulatingT cell responses.

Extraction of iridium (IV) from hydrochloric acid media with crown ether in chloroform, and its determination by ICP-AES

A new method for the quantitative extraction and determination of trace amounts of iridium from hydrochloric acid media has been established based on the formation of an ion-association complex of iridium hexachloro anion IrCl6(2-) with dicyclohexyl-18-crown-6 (DC18C6) oxonium cation in chloroform, then determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The effect of various factors (solvent, acid concentration, crown ether, reagent concentration, shaking time, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of iridium has been investigated. The procedure was used to determine traces of iridium in palladium chloride and rhodium chloride.