Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba

Absolute quantification of the budding yeast transcriptome by means of competitive PCR between genomic and complementary DNAs

<p>Abstract</p> <p>Background</p> <p>An ideal format to describe transcriptome would be its composition measured on the scale of absolute numbers of individual mRNAs per cell. It would help not only to precisely grasp the structure of the transcriptome but also to accelerate data exchange and integration.</p> <p>Results</p> <p>We conceived an idea of competitive PCR between genomic DNA and cDNA. Since the former contains every gene exactly at the same copy number, it can serve as an ideal normalization standard for the latter to obtain stoichiometric composition data of the transcriptome. This data can then be easily converted to absolute quantification data provided with an appropriate calibration. To implement this idea, we improved adaptor-tagged competitive PCR, originally developed for relative quantification of the 3'-end restriction fragment of each cDNA, such that it can be applied to any restriction fragment. We demonstrated that this "generalized" adaptor-tagged competitive PCR (GATC-PCR) can be performed between genomic DNA and cDNA to accurately measure absolute expression level of each mRNA in the budding yeast <it>Saccharomyces cerevisiae</it>. Furthermore, we constructed a large-scale GATC-PCR system to measure absolute expression levels of 5,038 genes to show that the yeast contains more than 30,000 copies of mRNA molecules per cell.</p> <p>Conclusion</p> <p>We developed a GATC-PCR method to accurately measure absolute expression levels of mRNAs by means of competitive amplification of genomic and cDNA copies of each gene. A large-scale application of GATC-PCR to the budding yeast transcriptome revealed that it is twice or more as large as previously estimated. This method is flexibly applicable to both targeted and genome-wide analyses of absolute expression levels of mRNAs.</p

Amyloid β-mediated Zn2+ influx into dentate granule cells transiently induces a short-term cognitive deficit.

We examined an idea that short-term cognition is transiently affected by a state of confusion in Zn2+ transport system due to a local increase in amyloid-β (Aβ) concentration. A single injection of Aβ (25 pmol) into the dentate gyrus affected dentate gyrus long-term potentiation (LTP) 1 h after the injection, but not 4 h after the injection. Simultaneously, 1-h memory of object recognition was affected when the training was performed 1 h after the injection, but not 4 h after the injection. Aβ-mediated impairments of LTP and memory were rescued in the presence of zinc chelators, suggesting that Zn2+ is involved in Aβ action. When Aβ was injected into the dentate gyrus, intracellular Zn2+ levels were increased only in the injected area in the dentate gyrus, suggesting that Aβ induces the influx of Zn2+ into cells in the injected area. When Aβ was added to hippocampal slices, Aβ did not increase intracellular Zn2+ levels in the dentate granule cell layer in ACSF without Zn2+, but in ACSF containing Zn2+. The increase in intracellular Zn2+ levels was inhibited in the presence of CaEDTA, an extracellular zinc chelator, but not in the presence of CNQX, an AMPA receptor antagonist. The present study indicates that Aβ-mediated Zn2+ influx into dentate granule cells, which may occur without AMPA receptor activation, transiently induces a short-term cognitive deficit. Extracellular Zn2+ may play a key role for transiently Aβ-induced cognition deficits

Extracellular Zn2+ is essential for amyloid beta1-42-induced cognitive decline in the normal brain and its rescue

Brain Aβ1-42 accumulation is considered an upstream event in pathogenesis of Alzheimer's disease. However, accumulating evidence indicates that other neurochemical changes potentiate the toxicity of this constitutively generated peptide. Here we report that the interaction of Aβ1-42 with extracellular Zn2+ is essential for in vivo rapid uptake of Aβ1-42 and Zn2+ into dentate granule cells in the normal rat hippocampus. The uptake of both Aβ1-42 and Zn2+ was blocked by CaEDTA, an extracellular Zn2+ chelator, and by Cd2+, a metal that displaces Zn2+ for Aβ1-42 binding. In vivo perforant pathway LTP was unaffected by perfusion with 1000 nm Aβ1-42 in ACSF without Zn2+ However, LTP was attenuated under preperfusion with 5 nm Aβ1-42 in ACSF containing 10 nm Zn2+, recapitulating the concentration of extracellular Zn2+, but not with 5 nm Aβ1-40 in ACSF containing 10 nm Zn2+ Aβ1-40 and Zn2+ were not taken up into dentate granule cells under these conditions, consistent with lower affinity of Aβ1-40 for Zn2+ than Aβ1-42 Aβ1-42-induced attenuation of LTP was rescued by both CaEDTA and CdCl2, and was observed even with 500 pm Aβ1-42 Aβ1-42 injected into the dentate granule cell layer of rats induced a rapid memory disturbance that was also rescued by coinjection of CdCl2 The present study supports blocking the formation of Zn-Aβ1-42 in the extracellular compartment as an effective preventive strategy for Alzheimer's disease.SIGNIFICANCE STATEMENT Short-term memory loss occurs in normal elderly and increases in the predementia stage of Alzheimer's disease (AD). Amyloid-β1-42 (Aβ1-42), a possible causing peptide in AD, is bound to Zn2+ in the extracellular compartment in the hippocampus induced short-term memory loss in the normal rat brain, suggesting that extracellular Zn2+ is essential for Aβ1-42-induced short-term memory loss. The evidence is important to find an effective preventive strategy for AD, which is blocking the formation of Zn-Aβ1-42 in the extracellular compartment

Transiently Aβ-induced memory deficit and its rescue with zinc chelators.

<p>(A) The object recognition test was performed 1 h after injection of saline (control) (n = 16), Aβ (25 pmol) (n = 13), Aβ + CaEDTA (500 pmol) (n = 10), and CaEDTA (n = 9) in saline (1 µl). ^*, p<0.05, vs. saline, ^#, p<0.05 (Tukey's test). (B) The object recognition test was performed 1 h after injection of saline (control) (n = 16), Aβ (25 pmol) (n = 13), and Aβ + ZnAF2-DA (100 pmol) (n = 12) in saline (1 µl). ^**, p<0.01, vs. saline, ^#, p<0.05 (Tukey's test). (C) Brain slices were prepared 1 h after bilateral injection of ZnAF-2DA (100 pmol, 100 µM/1 µl). Intracellular ZnAF-2 fluorescence was measured as the basal level for 30 s and then measured under stimulation with 50 mM KCl for 170 s. Note that intracellular ZnAF-2 fluorescence was observed only in a few slices including the injected area in the dentate gyrus. ML, molecular layer; GCL, granule cell layer. Bars, 50 µm. (D) The data represent the rate (%) of fluorescence intensity in the dentate granule cell layer 170 s after stimulation to that before the stimulation, which was represented as 100% (n = 5). ***, p<0.001 (paired t-test). vs. base. (E and F) LTP was induced 4 h after injection of saline (n = 9), Aβ (25 pmol) (n = 6), and Aβ + ZnCl₂ (50 pmol) (n = 6) in saline (1 µl). No significant difference, vs. saline (Dunnett's test). (G) Representative fEPSP recordings at the time −250 min (before injection; light grey line), −20 min (after injection; dark grey line) and 50 min (after tetanic stimulation; black line) are shown. Scale bar, vertical axis (5 mV), cross axis (10 ms). (H) The object recognition test was performed 4 h after injection of saline (control) (n = 7) and Aβ (25 pmol) (n = 8) in saline (1 µl). No significant difference, vs. saline (t-test).</p

Aβ-induced attenuation of LTP.

<p>(A) LTP was induced 1 h after injection of saline (control, n = 7) and Aβ (2.5 (n = 4), 12.5 (n = 4), 25 pmol (n = 9)) in saline (1 µl) via an injection cannula. An inserted picture (coronal section) shows the position of an injection cannula attached to a recording electrode in the hippocampus (HIP). (B) Averaged PS amplitudes for the last 10 min were represented as the magnitude of LTP. *, p<0.05, vs. saline (Dunnett's test). (C) Representative fEPSP recordings at the time −70 min (before injection; light grey line), −20 min (after injection; dark grey line) and 50 min (after tetanic stimulation; black line) are shown. Note that fEPSPs after Aβ injection (dark grey line) were almost the same as those before Aβ injection (light grey line). Scale bar, vertical axis (5 mV), cross axis (10 ms). (D, E and F) LTP was induced 1 h after injection of Aβ (25 pmol, n = 9), Aβ + ZnCl₂ (50 pmol, n = 9), and ZnCl₂ (n = 4) in saline. *, p<0.05, ***, p<0.001, vs. saline (n = 7), ^#, p<0.05, ^##, p<0.001 (Tukey's test).</p

Increase in Aβ-mediated Zn²⁺ influx.

<p>(A) Brain slices were prepared 15 min after injection of saline containing ZnAF-2DA (100 pmol) and Aβ (25 pmol) in saline containing ZnAF-2DA (100 pmol) (1 µl) via an injection cannula and stained with calcium orange AM. Note that intracellular ZnAF-2 fluorescence was observed only in a few slices including the injected area in the dentate gyrus and not observed in the CA3 and CA1. G, dentate granule cell layer. H, hilus. Bars, 100 µm. (B) The data represent the ratios (%) of the fluorescence intensity after Aβ injection to that after saline injection that was expressed as 100% (n = 4). ^*, p<0.05 (t-test). (C) Hippocampal slices doubly stained with ZnAF-2DA and Calcium Orange AM were immersed in 400 µl ACSF containing 1500 nM ZnCl₂. After measuring each baseline fluorescence for 10 sec, 100 µl of saline (n = 13), 50 µM Aβ in saline (n = 15), 50 µM Aβ +200 µM CNQX in saline (n = 8), and 50 µM Aβ +5 mM CaEDTA in saline (n = 8) was added to hippocampal slices in ACSF and both fluorescence was measured for 160 sec. The images of the dentate gyrus were obtained 160 s after addition. Bars; 50 µm. (D) The data represent the ratios (%) of the fluorescence after the addition (150–160 sec) to the baseline fluorescence (0–10 sec) that was expressed as 100%. ^*, p<0.05, vs. saline, ^#, p<0.05 (Tukey's test). No significant difference in calcium orange intensity, vs. saline (Dunnett's test).</p

Rescue of Aβ-induced attenuation of LTP with zinc chelators.

<p>(A, B, and C) LTP was induced 1 h after injection of Aβ (25 pmol) (n = 9), Aβ + CaEDTA (500 pmol) (n = 8), and CaEDTA (n = 7) in saline (1 µl). *, p<0.01, vs. saline (n = 7), ^#, p<0.05 (Tukey's test). (D, E, and F) LTP was induced 1 h after injection of Aβ (25 pmol) (n = 9) and Aβ + ZnAF-2DA (100 pmol) (n = 7) in saline (1 µl). *, p<0.05, vs. saline, ^#, p<0.05 (Tukey's test).</p