Loss of AtPDR8, a Plasma Membrane ABC Transporter of Arabidopsis thaliana, Causes Hypersensitive Cell Death Upon Pathogen Infection

Plants contain a large number of ATP-binding cassette (ABC) transporters belonging to different subclasses. AtPDR8 is the only member of the pleiotropic drug resistance (PDR) ABC transporter subclass in Arabidopsis that is constitutively highly expressed. In transgenic Arabidopsis plants harboring the AtPDR8 promoter fused to β-glucuronidase (GUS), reporter expression was shown to be strong in the stomata and hydathode. In the stomata, transcripts of AtPDR8 were particularly frequent in the cells surrounding air spaces. Subcellular fractionation and immunochemical analysis showed that AtPDR8 was localized in the plasma membrane. When a knockout mutant of AtPDR8 (atpdr8) was infected with bacterial and oomycete pathogens, the plants exhibited chlorotic lesions and a hypersensitive response (HR)-like cell death. Cell death was detected in the atpdr8 mutants within 10h of infection with the virulent bacterial pathogen, Pseudomonas syringae. As a result, the growth of P. syringae in the leaves of the atpdr8 mutant was reduced to 1% of that in the wild type. The defense response genes, PR-1, PR-2, PR-5, VPEγ, AtrbohD and AtrbohF were highly expressed when the mutant plants were grown under non-sterile conditions. The expression of the AtPDR8 gene was enhanced by infection of virulent and avirulent bacterial pathogens. Our results indicate that AtPDR8 is a key factor controlling the extent of cell death in the defense response and suggest that AtPDR8 transports some substance(s) which is closely related to the response of plants to pathogen

Induction of apoptosis during the early phase of reperfusion after rat liver ischemia

This study was designed to investigate the induction of apoptosis during the reperfusion phase following warm liver ischemia in vivo. We evaluated apoptotic bodies (ABs) in sections stained with hematoxylin and eosin (H. E.) and positive hepatocytes in sections stained by the in situ nick end labeling method (TUNEL method) during the reperfusion phase up to 48 h after a 70% liver ischemia for 30 or 60min in duration (30 or 60 min group). The peak number of ABs in H. E.-stained sections was observed at 1 to 3 h in the 30 min group and 3 to 6 h in the 60 min group. The number of ABs gradually fell as the length of the perfusion period increased, and few ABs were observed at 24 and 48 h after reperfusion. A peak number of TUNEL-positive hepatocytes was recognized at 3 h after reperfusion in both groups, after which the numbers decreased gradually. DNA extracted from both groups was electrophoresed on a 1.5% agarose gel. In both groups, a ladder-like pattern over smear pattern was recognized at 3 h after reperfusion. These results show that hepatocyte apoptosis was induced during the early phase of reperfusion after rat liver ischemia morphologically and biochemically, which suggests that hepatocyte apoptosis may be associated with ischemia and reperfusion injury.</p

L1L_1-Norm Ball for CSIDH: Optimal Strategy for Choosing the Secret Key Space

Isogeny-based cryptography is a kind of post-quantum cryptography whose security relies on the hardness of an isogeny problem over elliptic curves. In this paper, we study CSIDH, which is one of isogeny-based cryptography presented by Castryck et al. in Asiacrypt 2018. In CSIDH, the secret key is taken from an $L_\infty$-norm ball of integer vectors and the public key is generated by calculating the action of an ideal class corresponding to a secret key. For faster key exchange, it is important to accelerate the algorithm calculating the action of the ideal class group, many such approaches have been studied recently. Several papers showed that CSIDH becomes more efficient when a secret key space is changed to weighted $L_\infty$-norm ball. In this paper, we revisit the approach and try to find an optimal secret key space which minimizes the computational cost of the group action. At first, we obtain an optimal secret key space by analyzing computational cost of CSIDH with respect to the number of operations on $\mathbb{F}_p$. Since the optimal key space is too complicated to sample a secret key uniformly, we approximate the optimal key space by using $L_1$-norm ball and propose algorithms for uniform sampling with some precomputed table. By experiment with CSIDH-512, we show that the computational cost of the $L_1$-norm ball is reduced by about 20\% compared to that of the $L_\infty$-norm ball, using a precomputed table of 160 Kbytes. The cost is only 1.08 times of the cost of the optimal secret key space. Finally, we also discuss possible sampling algorithms using other norm balls and their efficiency

Noiseless Collective Motion out of Noisy Chaos

We consider the effect of microscopic external noise on the collective motion of a globally coupled map in fully desynchronized states. Without the external noise a macroscopic variable shows high-dimensional chaos distinguishable from random motion. With the increase of external noise intensity, the collective motion is successively simplified. The number of effective degrees of freedom in the collective motion is found to decrease as $-\log{\sigma^2}$ with the external noise variance $\sigma^2$. It is shown how the microscopic noise can suppress the number of degrees of freedom at a macroscopic level.Comment: 9 pages RevTex file and 4 postscript figure

Collective motions in globally coupled tent maps with stochastic updating

We study a generalization of globally coupled maps, where the elements are updated with probability $p$. When $p$ is below a threshold $p_c$, the collective motion vanishes and the system is the stationary state in the large size limit. We present the linear stability analysis.Comment: 6 pages including 5 figure

Analysis of the immune status in the recipients with long-term well-functioning kidneys allografts.

The immune status of thirteen living and related kidney transplant recipients with stable allografts were examined. The immunological assays consisted of a mixed lymphocyte reaction (MLR), cell-mediated lympholysis (CML) assay, interleukin-2 (IL-2) production in mixed lymphocytes culture (MLC) and IL-2 receptor (IL-2 R) expression on MLC cells. The suppression rates of the monoclonal antibodies (mAbs) against IL-2 R were tested on MLRs. The stimulation indices (SI) of the MLR against both donor and third-party cells increased compared with those of pretransplantation. The MLC responder cells stimulated by donor cells produced detectable amounts of IL-2, these amounts were lower than those by third-party cells. The MLC cells against donor cells expressed IL-2 R alpha and beta chains to the same degree as those against third-party cells. Anti-IL-2 R mAbs equally inhibited the MLRs between recipient and donor or third-party cells. Cytotoxic T lymphocytes (CTL) against donor cells were not generated, even with the addition of recombinant IL-2 in any of recipients except one, while anti-donor CTL had been detected prior to transplantation and the CTL against third-party cells were induced in posttranspalnt CML assays. These results indicate that the clonal anergy phenomenon might mediate the specific CTL unresponsiveness observed in kidney transplant recipients and the anergy phenomenon might serve in the long-term acceptance of allograft.</p

Current Topics in Food and Biodynamic Chemistry Research

Studies on chemical structures, metabolisms and physiological significances of food and bioactive natural products are currently being addressed in our laboratory to explain their health effects in humans. Some novel molecules and functions of food and nutrients were discovered, and new foodstuffs and products were developed. The researches were carried out on stable authentic phosphatidylcholine hydroperoxide; membrane lipid glycation and its inhibitors; cancer growth suppression by conjugated triene fatty acids; antiangiogenicity of rice bran tocotrienol; glucosidase inhibition by mulberry 1-deoxynojirimycin; and high quality broccoli products regarding hepatoprotective sulforaphane contents

A fluorenylidene-acridane that becomes dark in color upon grinding – ground state mechanochromism by conformational change

UTokyo FOCUS Articles掲載「力を加えると大きく色が変わる分子を発見 電気の流れやすさも変化」https://www.u-tokyo.ac.jp/focus/ja/articles/z0508_00130.htmlUTokyo FOCUS Articles "New molecule responds to mechanical pressure with drastic color change : Mechanical stimulus also enhances electron mobility" https://www.u-tokyo.ac.jp/focus/en/articles/z0508_00129.htm