Transient Expression of CD20 Antigen (Pan B Cell Marker) in Activated Lymph Node T Cells

In contrast to the case of peripheral T cells, the surface expression of CD20 antigen and the expression of CD20 mRNA in monkey lymph node (LN) T cells underwent a noticeable increase when they were cultured with mitogen and interleukin-2 (IL-2). To confirm in vivo regulation of CD20 expression during the activation of LN T cells, we examined LNs derived from monkeys experimentally inoculated with simian immunodeficiency virus (SIV). Significant expression of CD20 antigen was detected in the T cells of the LNs at the stage of lymphadenopathy. These findings suggest that lymphocyte activation in the LNs induced expression of the CD20 molecule in some T cells.     

Phencyclidine-induced expression of c-Fos-like immunoreactivity in mouse brain regions

For the purpose of studying a role of immediate early genes in psychotomimetic-induced behavioral excitation, we experimentally enhanced the locomotor activity of mice by acute administration of phencyclidine and examined the expression and localization of the c-Fos-like and c-Jun-like immunoreactivities in brain regions. A single injection of phencyclidine (5.0 mg/kg, i.p.) significantly increased not only the locomotor activity but also the expression of c-Fos-like immunoreactivity in several brain regions, particularly in the parietal cortex, hippocampal dentate gyrus, piriform cortex and hypothalamus. Interestingly, the c-Fos-like immunoreactivity in the parietal cortex continued to increase for 1 week after the phencyclidine injection. These results indicate that phencyclidine, even injected only once, can induce the persistent expression of c-Fos or c-Fos-related protein(s) in the mouse brain, and also suggest the possibility that such a c-Fos expression may underlie the behavioral and/or psychotomimetic effects of phencyclidine.     

Induction and Repair of Damage to DNA in Cucumber Cotyledons Irradiated with UV-B

Photoinduced lesions in DNA, namely, cyclobutane pyrimidinedimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts[(6-4)photoproducts], in cucumber cotyledons that had been irradiatedwith naturally occurring levels of UV-B (290–320 nm) werequantitated by enzyme-linked immunosorbent assays with monoclonalantibodies specific to each type of photolesion. Induction ofthese photolesions was dependent on temperature and their extentwas reduced by simultaneous irradiation with white light. Thedark repair of both types of photolesion was undetectable. Light-dependentremoval of (6-4)photoproducts was very slow, with 50% removalin 4 h. By contrast, 50% of initial CPDs were removed within15 min. Both photorepair processes were dependent on the intensityof white light and were sensitive to temperature. These resultsindicate that high photolyase activity is present in cucumbercotyledons and that repair activities in cucumber cotyledonsare different from those reported in Arabidopsis, in which (6-4)photoproductsare photorepaired more rapidly than CPDs. (Received October 13, 1995; Accepted December 28, 1995)     

Mechanism of Electron Flow through the QB Site in Photosystem II. 4. Reaction Mechanism of Plastoquinone Derivatives at the QB Site in Spinach Photosystem II Membrane Fragments

Interactions of externally added plastoquinone (PQ) derivatives(PQ₀-PQ₃) with the photosystem II (PSII) acceptor side wereinvestigated in PSII membrane fragments prepared from spinachby measuring the photoreduction rates of PQ derivatives at variousPQ concentrations, and the following results were obtained. From the kinetic analysis, all the PQ derivatives (PQ₀-PQ₃)except PQ₃ were shown to accept electrons at two sites (theQ_B site and the PQ site) as in the case of Synechococcus vulcanusPSII particles with benzoquinone derivatives [Satoh et al. (1995)Plant Cell Physiol. 36: 597]. Affinities of PQ derivatives at the Q_B site increased as thelength of the isoprene side chain got longer, while those atthe PQ site were not very much different for all the PQ derivativestested in this study. The inhibitory effect of DCMU was noncompetitive, and, therefore,the affinity of PQ₃ for the PQ site was determined while thatfor the Q_B site could not be estimated presumably due to itsfairly high affinity to the site. Based on the results obtained using PQ derivatives, the mechanismof interaction of an authentic PQ, PQ₉, at the Q_B site is discussed. (Received May 2, 1996; Accepted July 24, 1996)     

Promotion of Cocklebur Seed Germination by Allyl, Sulfur and Cyanogenic Compounds

The effects of allyl, sulfur and cyanogenic compounds on thegermination of upper cocklebur (Xanthium pennsylvanicum Wallr.)seeds were examined. Mercaptoethanol and methylmercaptan aswell as KCN, substrates for rßcyanoalanine synthase(CAS), and H₂S and thiocyanate, the products of the CAS catalyzingreaction, were effective in promoting germination, suggestingthe involvement of CAS in germination. Most of allyl compounds, especially allylthiourea, as well asethylene which activated CAS [Hasegawa et al. (1994) Physiol.Plant. 91: 141], promoted the germination in an abnormal typewhich occurred by the predominant growth of cotyledons as didC₂H₄ [Katoh and Esashi (1975) Plant Cell Physiol. 16: 687].However, they failed to activate CAS unlike ethylene, and toliberate free ethylene during an incubation period. It was thuspossible that an C₂H₄-like double bond within allyl compoundscan act to promote seed germination. (Received June 10, 1996; Accepted August 21, 1996)     

Immunohistochemical characteristics of the constituents of senile plaques and amyloid angiopathy in aged cynomolgus monkeys

Abstract: In this study, we immunohistochemically examined the several constituents of senile plaques (SPs) and cerebral amyloid angiopathy (CAA) in aged cynomolgus monkeys. Apolipoprotein E (apoE) deposited in all mature plaques and CAA, and in half of the diffuse plaques. Alpha-1-antichymotripsin (αACT) deposited in half of the mature plaques and in one third of the CAA. Amyloid precursor protein (APP), ubiquitin (Ub), and microtubule-associated protein-2 (MAP-2) accumulated in the swollen neurites of mature plaques. Glial fibrillary acidic protein (GFAP) was detected in the astrocytes and their processes surrounding the mature plaques. Tau was detected in neither the SPs nor CAA. Therefore, mature plaques involved extracellular Aβ, apoE, and αACT, and also astrocytes and swollen neurites. However, diffuse plaques involved only extracellular Aβ and apoE. Since these features, except for tau, were consistent with those in humans, this animal model will be useful for studying the pathogenesis of cerebral amyloid deposition.     

The CLS2 gene encodes a protein with multiple membrane-spanning domains that is important Ca2+ tolerance in yeast

Genetic screening of Saccharomyces cerevisiae mutants defective in Ca²⁺ homeostasis identified cls2, which exhibits a specific Ca²⁺-sensitive growth phenotype. We describe here the CLS2 gene and a multicopy suppressor (named BCL21, for bypass of CLS2) of the cls2 mutation. The CLS2 gene encodes a polypeptide of 410 amino acid residues, and its hydropathy profile indicates that the predicted Cls2 protein (Cls2p) contains ten putative membrane spanning regions. Immunofluorescent staining of the yeast cells expressing epitopetagged Cls2p suggests that Cls2p is localized to endoplasmatic reticulum (ER) membrane. A cls2 disruption strain is viable, but shows a Ca²⁺-sensitive phenotype like the original cls2 mutants. BCL21 suppresses the cls2 disruption mutation, indicating that the multicopy suppression does not require the Cls2p. Suppression of cls2 was observed even after introduction of a singlecopy plasmid harboring BCL21. The BCL21 gene encodes a protein of 382 amino acid residues and is identical to the SUR1 gene. sur1 was originally isolated as a suppressor of rvs161, which has reduced viability in nutrient starvation conditions. Possible mechanisms of the multicopy suppression are discussed.     

Fission yeast cut3 and cut14, members of a ubiquitous protein family, are required for chromosome condensation and segregation in mitosis.

Fission yeast temperature-sensitive mutants cut3-477 and cut14-208 fail to condense chromosomes but small portions of the chromosomes can separate along the spindle during mitosis, producing phi-shaped chromosomes. Septation and cell division occur in the absence of normal nuclear division, causing the cut phenotype. Fluorescence in situ hybridization demonstrated that the contraction of the chromosome arm during mitosis was defective. Mutant chromosomes are apparently not rigid enough to be transported poleward by the spindle. Loss of the cut3 protein by gene disruption fails to maintain the nuclear chromatin architecture even in interphase. Both cut3 and cut14 proteins contain a putative nucleoside triphosphate (NTP)-binding domain and belong to the same ubiquitous protein family which includes the budding yeast Smc1 protein. The cut3 mutant was suppressed by an increase in the cut14+ gene dosage. The cut3 protein, having the highest similarity to the mouse protein, is localized in the nucleus throughout the cell cycle. Plasmids carrying the DNA topoisomerase I gene partly suppressed the temperature sensitive phenotype of cut3-477, suggesting that the cut3 protein might be involved in chromosome DNA topology.     

Activation of Xenopus Eggs by an Extract of Cynops Sperm

An extract obtained from Cynops sperm induced the activation of both Cynops and Xenopus eggs with accompanying changes in the potential of the egg membrane that were quite similar to those caused by the Cynops sperm. The activation-inducing properties of the extract were abolished by treatment with proteinase K or by heating (60°C, 15 min) and were associated with a protease activity against peptidyl Arg-MCA substrates. The activation of Xenopus eggs by the extract was inhibited by those substrates, or by protease inhibitors, aprotinin or leupeptin. The protease activity was localized in the acrosomal region of Cynops sperm. The activation of Xenopus eggs by the extract was prevented when the exterior concentration of Ca²⁺ions, [Ca²⁺]₀, was reduced to 1.5 μM, but it was enhanced when [Ca²⁺]₀ was increased to 340 μM. The activation of Xenopus eggs by the extract was not affected by positive clamping when [Ca²⁺]₀ was 340 μM. These results suggest that the sperm extract contains a protease that causes an increase in the influx of Ca²⁺ions that results in voltage-insensitive activation of the egg.     

Chemiosmotic coupling of ion transport in the yeast vacuole: Its role in acidification inside organelles

Acidification inside the vacuo-lysosome systems is ubiquitous in eukaryotic organisms and essential for organelle functions. The acidification of these organelles is accomplished by proton-translocating ATPase belonging to the V-type H⁺-ATPase superfamily. However, in terms of chemiosmotic energy transduction, electrogenic proton pumping alone is not sufficient to establish and maintain those compartments inside acidic. Current studies have shown that thein situ acidification depends upon the activity of V-ATPase and vacuolar anion conductance; the latter is required for shunting a membrane potential (interior positive) generated by the positively charged proton translocation. Yeast vacuoles possess two distinct Cl^– transport systems both participating in the acidification inside the vacuole, a large acidic compartment with digestive and storage functions. These two transport systems have distinct characteristics for their kinetics of Cl^– uptake or sensitivity to a stilbene derivative. One shows linear dependence on a Cl^– concentration and is inhibited by 4,4-diisothiocyano-2,2-stilbenedisulfonic acid (DIDS). The other shows saturable kinetics with an apparentK _m for Cl^– of approximately 20 mM. Molecular mechanisms of the chemiosmotic coupling in the vacuolar ion transport and acidification inside are discussed in detail.