Revealing the short-range structure of the mirror nuclei 3H and 3He.

When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1-3, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3-5. Two-nucleon knockout or 'triple coincidence' reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6-8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon-nucleon interaction.

Novel Measurement of the Neutron Magnetic Form Factor from A=3 Mirror Nuclei.

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^{3}H and ^{3}He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6

Observation of Λ(4)H Hyperhydrogen by Decay-Pion Spectroscopy in Electron Scattering.

At the Mainz Microtron MAMI, the first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a (9)Be target in order to study the Λ binding energy of light hypernuclei. Positively charged kaons were detected by a short-orbit spectrometer with a broad momentum acceptance at 0° forward angles with respect to the beam, efficiently tagging the production of strangeness in the target nucleus. Coincidentally, negatively charged decay pions were detected by two independent high-resolution spectrometers. About 10(3) pionic weak decays of hyperfragments and hyperons were observed. The pion momentum distribution shows a monochromatic peak at pπ≈133 MeV/c, corresponding to the unique signature for the two-body decay of hyperhydrogen Λ(4)H→(4)He+π(-), stopped inside the target. Its Λ binding energy was determined to be BΛ=2.12±0.01 (stat)±0.09 (syst)MeV with respect to the (3)H+Λ mass.

Observation of the (Λ)(7)He hypernucleus by the (e, e'K+) reaction.

An experiment with a newly developed high-resolution kaon spectrometer and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab. The ground state of a neutron-rich hypernucleus, (Λ)(7)He, was observed for the first time with the (e, e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The (Λ)(7)He binding energy supplies the last missing information of the A = 7, T = 1 hypernuclear isotriplet, providing a new input for the charge symmetry breaking effect of the ΛN potential.

Chemical form of cadmium (and other heavy metals) in rice and wheat plants.

Chemical forms of heavy metals such as Cd, Cu, Ni, and Pb in rice and wheat plants grown in nutrient solution containing a heavy metal were investigated. Fractionation of an extract of Cd-treated rice plants on Sephadex G-75 showed cadmium to be associated with organic compounds of high (fraction A), intermediary (fraction B), and low molecular weight (fraction C). Material A, whose molecular weight was greater than 440,000, is probably nonspecific binding of Cd to normal cell components. Materials B and C can be classified as types of metallothionein. The molecular weight of B was 33,100. This material contains 12 mg Cd/g protein. The UV-absorption spectrum of B showed absorptions at 280 and 250 nm. Material B was not eluted even at a very high ionic strength from the DEAE-cellulose column, but it was eluted at a very low ionic strength from a CM-cellulose column, indicating a highly anionic molecule which differs from metallothionein in animals. Fraction C contains two materials: one a Cd-containing material whose molecular weight was estimated to be approximately 7000 and the other an inorganic Cd salt. In addition to cadmium, copper, lead, and nickel in rice and wheat have been studied. As a result, heavy metal-containing materials whose molecular weights were estimated to be approximately 16,000 and 8900 (Ni-treated rice plants), 7000 (Pb-treated rice plants), 5000 (Cd-treated wheat plants), and 21,000 (Cu-treated wheat plants) were isolated.

Antideuteron production in 158A GeV/c Pb + Pb collisions

The invariant cross section as a function of transverse momentum for antideuterons produced in 158A GeV/c per nucleon Pb+Pb central collisions has been measured by the NA44 experiment at CERN. This measurement, together with a measurement of antiprotons, allows for the determination of the antideuteron coalescence parameter. The extracted coalescence radius is found to agree with the deuteron coalescence radius and radii determined from two particle correlations.

The third zinc finger of TFIIIA stabilizes a hairpin structure of the non-coding strand in the internal control region of 5S RNA gene.

The structures of non-coding and coding strands in box C of the internal control region (ICR) of Xenopus laevis somatic 5S RNA gene have been examined by circular dichroism (CD) and Raman spectroscopy in the absence and presence of the third zinc finger of transcription factor IIIA (TFIIIA), which binds to the ICR. The non-coding strand exhibits CD signals assignable to a hairpin and an unfolded structure. The presence of the hairpin structure is supported by Raman spectra, gel electrophoresis, and nucleotide deletion experiments. Binding of the zinc finger to the non-coding strand increases the CD signal of hairpin structure, indicating stabilization of the hairpin structure by the zinc finger. In contrast, the corresponding coding strand remains unfolded even in the presence of the zinc finger. The TFIIIA-ICR complex is not only required for initiation of transcription but also lasts during many rounds of transcription of the 5S RNA gene including the ICR (Bogenhagen et al., Cell 28 (1982) 413). TFIIIA may play a role in promoting the transcription by maintaining the unwound non-coding strand in the hairpin structure and leaving the coding strand available for transcription by RNA polymerase.

[Effect of gonadectomy on juxtaglomerular cells in mice: qualitative and quantitative electron microscopy (author's transl)].

Effect of gonadectomy on juxtaglomerular cells of the kidney was examined by qualitative and quantitative electron microscopy. Mice were gondectomized at 25 or 60 days of age and examined at 110 days of age. For quantitative analysis, the volume ratios of nucleus, specific granules, Golgi apparatus, rough endoplasmic reticulum and mitochondria to cell were obtained stereologically. In normal mice, the juxtaglomerular cells contained numerous specific granules. The Golgi apparatus was not well developed and the rough endoplasmic reticulum was generally flat and short in profile. In males castrated at 25 days, the specific granules were significantly increased in amount. In male castrated at 60 days, the specific granules were increased in amount, and the Golgi apparatus and rough endoplasmic reticulum were well developed. Crystalline granules were frequently seen around the Golgi area. In females, ovariectomy caused no significant change in juxtaglomerular cells.

[Juxtaglomerular cells after removal of the submandibular glands in male mice: quantitative electron microscopy (author's transl)].

The juxtaglomerular cells in the kidney were studied qualitatively and quantitatively on the 7th and 49th day after removal of the bilateral submandibular glands at 60 days of age in male mice. In normal mice, the juxtaglomerular cells contained numerous specific granules. The Golgi apparatus was not well developed and the rough endoplasmic reticulum was generally flat and short in profile. At 7 days after extirpation of the submandibular glands, the specific granules were sparsely distributed, the Golgi apparatus was relatively prominent, and the rough endoplasmic reticulum was dilated and increased in amount. At 49 days after operation, the specific granules were increased in number, and the Golgi apparatus and rough endoplasmic reticulum were as prominent as at 7 days. The volume ratios of the nucleus, specific granules, Golgi apparatus, rough endoplasmic reticulum and mitochondria were examined by quantitative electron microscopy. After operation, the volume ratio of specific granules was significantly decreased at 7 days, but was increased at 49 days. The volume ratios of Golgi apparatus and rough endoplasmic reticulum were significantly increased at both 7 and 49 days after operation. The volume ratios of nucleus and mitochondria showed no significant difference from those in normal and sham-operated mice. The volumes of adrenal cortex and medulla at 49 days after operation were also examined by quantitative microscopy. They were not significantly different from those in normal mice.

Differential expression of the immediate-early 2 and 3 proteins in developing mouse brains infected with murine cytomegalovirus.

Murine cytomegalovirus (MCMV) immediate-early (IE) 2 protein has been reported to be dispensable for growth and latency in mice. Therefore, its role in viral pathogenesis and tissue tropism is not known. Here we prepared specific antibodies to the IE2 and IE3 proteins by using fusion proteins expressed in Escherichia coli as antigens. Immunostaining of MCMV-infected cultured fibroblasts revealed IE2 protein to be expressed diffusely in the nucleoplasm similar to the IE1 protein. In contrast, expression of the IE3 protein, 88 kDa, exhibited a punctate pattern in the nucleus in the early phase of infection then diminished. In the brain of neonatal mice infected with MCMV, both IE2 and IE3 proteins were detected immunohistochemically in the cells of the ventricular walls early in infection. When the infection was prolonged, the IE2 protein was expressed in neurons of the cortex and hippocampus, while the IE3 protein was preferentially expressed in glial cells in the early phase of infection, and its levels declined during the infection. These results suggest that the IE2 protein may play a role in persistent infection in neurons, whereas the IE3 protein, expressed preferentially in glial cells, may play the main role in acute infection.

Juxtaglomerular cells in mice after long-term treatment with captopril--an electron microscopic study.

In mice, the juxtaglomerular cells were examined using qualitative and quantitative electron microscopy after an administration of captopril. After treatment with captopril for 2, 7 and 14 days, the specific granules were decreased in number, the Golgi apparatus was well developed, and the rough endoplasmic reticulum was dilated in profile. In the dilated rough endoplasmic reticulum, the intracisternal granules were occasionally seen after a 2-day treatment, were increased in size and number after a 7-day treatment and were hardly seen after a 14-day treatment. In a few cells associated with intracisternal granules on the 7th day, the Golgi apparatus was not well developed and some lysosomal bodies containing granules similar to the intracisternal granules were seen. In these cells, an excess of the intracisternal granules may be controlled by lysosomes. These findings suggest that the juxtaglomerular cells stimulate renin synthesis after long-term treatment with captopril, but a further increase in renin synthesis cannot be expected after the 7th day.

Detection of tetracycline resistance protein encoded by Bacillus subtilis plasmid pNS1.

Tetracycline resistance protein (TET) of Bacillus subtilis plasmid pNS1 was detected by immunoblot analysis using a specific antibody to TET-chloramphenicol acetyltransferase (CAT) fusion protein. In two-dimensional electrophoresis, one major spot which seemed to be the pNS1-encoded TET (pNS1-TET), was detected by immunostaining. Its molecular weight and isoelectric point were approximately 52 kDa and 6.2, respectively. Judging from the nucleotide sequence, the pNS1-TET is a very hydrophobic, 50 kDa protein. Therefore, the 52 kDa protein is thought to be an intact form of the pNS1-TET produced by B. subtilis cells.

Appearance of dense granules in the rough endoplasmic reticulum of the juxtaglomerular cells in mice administered with captopril.

Captopril [1-(D-3-mercapto-2-methyl-1-oxopropyl)-L-proline (S,S)] is now known to be an inhibitor of angiotensin-converting enzyme. In male mice, the juxtaglomerular cells were examined by electron microscopy 42 h after administration of captopril. Numerous dense granules appeared in the rough endoplasmic reticulum of these cells.

Cytometric analysis of small lymphocytes in the bone marrow and lymphatic tissues in neonatally thymectomized and nude mice, with particular reference to differentiation of B-lymphocytes.

In neonatally thymectomized mice and nude mice, small lymphocytes in the bone marrow, Peyer's patches, lymph nodes and spleen were studied qualitatively and quantitatively by electron microscopy. Marrow lymphocytes which are mostly small lymphocytes are classified into dark and light types. The greater proportion of marrow small lymphocytes are of the dark type. Small lymphocytes in Peyer's patches, lymph nodes and spleen are of the light type. The nuclear and cellular sizes of small lymphocytes were estimated stereologically. The nucleus-cell ratio, the volumetric proportions of mitochondria, Golgi apparatus, tubular complexes and dense bodies to the cell body and the proportions of nucleoli and nuclear bodies to the nucleus were also determined. The quantitative results thus obtained suggest that light small lymphocytes in the bone marrow are cytometrically similar to small lymphocytes in Peyer's patches, lymph nodes and spleen and that dark small lymphocytes in the bone marrow are different from other small lymphocytes. The findings are discussed in particular relation to morphological differentiation of B-lymphocytes.

A simple, sensitive bioassay for the detection of interleukin-1 using human melanoma A375 cell line.

Interleukin-1 (IL-1) exhibits multiple biological properties on various tissues by modulating immunologic, inflammatory, metabolic, and neurologic functions. Considerable attention has focussed on the measurement of IL-1 activity. We reported a simple, sensitive, and specific bioassay for IL-1 using human melanoma A375 subclone which is highly sensitive for the cell growth inhibitory activity of IL-1. This bioassay method is allows detection of as low as 10pg of IL-1 beta/ml or 30pg of IL-1 alpha/ml. Since this A375 subclone cell dose not respond to prostaglandin E2 plant lectins, lipopolysaccharide, and cytokines such as interleukin-2, interleukin-6, tumor necrosis factor, interferon or colony-stimulating factor, it is an extremely useful and rapid method for the measurement of IL-1 activity in a variety of experimental and clinical conditions. The assay method was used in the presence of antisera to IL-1 beta to discriminate two species of IL-1, IL-1 alpha and IL-1 beta, produced in human peripheral mononuclear cells.