Amplifiedbcl-2/JH rearrangements in reactive lymphadenopathy

Using the polymerase chain reaction (PCR) to examine the occurrence ofbcl-2/JH joining produced by t(14;18) chromosomal translocation, amplified DNA was detected in 2 of 18 lymph nodes showing reactive lymphadenopathy. The PCR was repeated in these two lymphs nodes using the same DNA samples, but no amplification was detected at the second attempt. Thus the amplified DNA was considered to be derived from one copy of joinedbcl-2/JH in one cell, or from a few copies in a few clonal cells with the same joinedbcl-2/JH. These results suggest that false joining ofbcl-2/JH at the t(14;l8) junction may occur in reactive lymph nodes.     

Pkn9, a Ser/Thr protein kinase involved in the development of Myxococcus xanthus

The Myxococcus xanthus gene, pkn9 , encodes a protein that contains significant homology with eukaryotic Ser/Thr protein kinases. The pkn9 gene was singled out of a previously identified family of kinase genes by amplification techniques that displayed differences in kinase gene expression during selected periods of the M. xanthus life cycle. Pkn9 was constitutively expressed during vegetative growth and upregulated during the aggregation stage of early development. It consists of 589 amino acids, and its N-terminal 394 residues show 38% identity with both Pkn1 and Pkn2 of M. xanthus . This region also shows 29, 25 and 29% identity with myosin light-chain kinase, protein kinase C, and cAMP-dependent protein kinase, respectively. A 22-residue hydrophobic transmembrane domain separates the kinase domain from the 173-residue C-terminal domain that resides on the outside of the inner membrane. The C-terminal domain contains two sets of tandem repeats of 13 and 10 residues which have no known function. When expressed in Escherichia coli under the T7 promoter, Pkn9 was found to be phosphorylated on serine and threonine residues. Disruption of the pkn9 kinase catalytic subdomains I–III by the insertion of a kanamycin-resistance gene resulted in slightly delayed, smaller and more-crowded fruiting bodies, while spore formation was normal. Total deletion of the pkn9 gene caused severely reduced progression through development resulting in light loose mounds that become slightly more compact over time. Development progressed further at the centre than at the edge of the spot, and spore formation was significantly reduced. Two-dimensional gel analysis revealed that both the disruption and the deletion of pkn9 prevented the expression of five membrane proteins (KREP9-1-4). These results suggest that the loss of Pkn9 kinase activity caused altered fruiting-body formation, the absence of the KREP9 proteins in the membrane, and reduced spore production.     

Characterization of an Enterotoxin Produced by Vibrio cholerae O139

A cholera-like enterotoxin was purified from Vibrio cholerae O139 strain AI-1841 isolated from a diarrheal patient in Bangladesh. Its characteristics were compared with that of cholera toxins (CTs) of classical strain 569B and El Tor strain KT25. Al-1841 produced as much toxin as O1 strains. The toxins were indistinguishable in terms of their migration profiles in conventional polyacrylamide gel disc electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectrofocusing as well as their affinity for hydroxyapatite. The skin permeability factor activity and the fluid accumulation induced in rabbit ileal loops of the toxin of AI-1841 were identical to those of the CTs. Three toxins equally reacted against anti-569B CT antiserum in Western blotting, and their B subunits formed a precipitin line against any anti-B subunit antiserum by double gel immunodiffusion. Anti-569B CTB antibody neutralized the three toxins in their PF activities and enterotoxicities. The amino acid sequence of 1841 toxin B subunit was identical with that of KT25 CTB, corresponding to the DNA sequence of ctxB from El Tor strains of the seventh pandemic. We concluded 1841 toxin was identical to CT of the seventh pandemic El Tor vibrios.     

Inhibition of indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase by β-carboline and indole derivatives

β-Carboline derivatives inhibited both indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase activities from various sources. Among them, norharman is most potent for both enzymes from mammalian sources. Kinetic studies revealed that norharman is uncompetitive (K_i = 0.12 mm) with l-tryptophan for rabbit intestinal indoleamine 2,3-dioxygenase, and linearly competitive (K_i = 0.29 mm) with l-tryptophan for mouse liver tryptophan 2,3-dioxygenase. In addition, some β-carbolines selectively inhibited one enzyme or the other. Pseudomonad tryptophan 2,3-dioxygenase was inhibited by a different spectrum of β-carbolines. Such a selective inhibition by the structure of substrate analogs is more evident by the use of indole derivatives. Indole-3-acetamide, indole-3-acetonitrile and indole-3-acrylic acid exhibited a potent inhibition for mammalian tryptophan 2,3-dioxygenase, while they moderately inhibited the pseudomonad enzyme. However, they showed no inhibition for indoleamine 2,3-dioxygenase. These results suggest the difference of the structures of the active sites among these enzymes from various sources.     

Comparison of stimulus-response (V-log I) functions in five types of lepidopteran compound eyes (46 species)

Summary Stimulus intensity-response relations (V-log I curves) were electrophysiologically (ERG) determined for the compound eyes of 46 lepidopteran species belonging to five different groups: butterflies (22 species), hesperids (3 species), diurnal sphingids (2 species), diurnal moths (3 species) and nocturnal moths (16 species). The V-log I curves were fitted to the Naka and Rushton equation, in whichn represents the slope of the linear part of each curve. The slopes so determined range fromn=0.35 (the shallowest slope) in nocturnal moths with the greatest dynamic range ton=0.54 (the steepest slope) in diurnal moths andn=0.53 in butterflies both of which have narrow dynamic range. Hesperids (n=0.41) and diurnal sphingids (n=0.38) have intermediate values between butterflies and nocturnal moths.The ratio of rhabdom to retinula volume is significantly higher in nocturnal moths (70–75%), however, those of butterflies and of diurnal moths are very small (2–5%), and hesperids and diurnal sphingids show intermediate ratio (ca. 25%).The slopes of V-log I curves are inversely proportional to the ratio of rhabdom to retinula volume in the various eye types. In all groups except diurnal moths, the light intensities which produce maximal and saturated responses are nearly the same, therefore the nocturnal moths which have the lowest threshold to light increase their sensitivity to dim light mainly by decreasing the slopes of V-log I curves.     

Enzymic mechanism of starch breakdown in germinating rice seeds : 11. Ultrastructural changes in scutellar epithelium

The ultrastructural changes occurring in the scutellar epithelium cells of rice seeds have been studied during germination and early seedling growth. During this time, several prominent structural changes occur, including (a) formation, development, and proliferation of organelles such as mitochondria, rough endoplasmic reticulum, free ribosomes, and Golgi apparatus; (b) folded structural modification of plasmamembranes in later stages; and (c) conspicuous decrease in lipid-storing spherosomes. Glyoxysome-like electron dense particles are detectable but their formation is much less prominent. It is conceivable that all these structural changes are related to the enhancement of the metabolic activities of the epithelial cells including the synthesis of hydrolytic enzymes such as α-amylase and their secretion into the endosperm tissues. Some enzyme activities characteristic of mitochondria and glyoxysomes have been determined using the crude scutellar extracts, and the results dealing with the low activities of the glyoxylate cycle enzymes and palmitoyl-coenzyme A oxidase appear to indicate that fatty acid breakdown is possibly via mitochondrial β-oxidation, although we reserve a definitive conclusion on the glyoxysomes being nonfunctional in fatty acid oxidation in rice seedlings.     

Demonstration of light-induced potential change in Chara cells lacking tonoplast

Chara cells without tonoplasts, prepared by replacing the cellsap with EGTA-containing media, showed essentially the samepattern of light-induced changes in membrane potential and membraneresistance as normal cells although the concentrations of ionsand ATP in the cytoplasm decreased considerably (1/3–1/10)after loss of the tonoplast. Removal of the tonoplast reducedthe rate of photosynthetic O₂ evolution to about 50% of thatof normal cells but did not affect the magnitude of light-inducedpotential change. Not a full but a certain level of electronflow seems necessary to activate the putative electrogenic H⁺-pump. ¹ Present address: Department of Botany, Faculty of Science,University of Tokyo, Japan. ² Present address: Niigata College of Pharmacy, Niigata 950-21,Japan. (Received September 4, 1978; )     

Onset of the constrictive effect of indomethacin on the ductus arteriosus in fetal rats.

The time of onset of the constrictive effect of indomethacin on the ductus arteriosus (DA) in fetal rats was assessed by measurement of the caliber of the DA after maternal treatment with indomethacin on days 19-21 of gestation. The day following overnight mating was regarded as day 0 of gestation. Observation was performed by direct exposure of the DA by hand shaving of intact frozen fetuses. On days 20 and 21, the DA was significantly constricted 3 h after maternal treatment with 1 mg/kg of indomethacin. When the DA was examined at 19 1/2 and 19 2/3 days of gestation (3 h after indomethacin exposure), it was significantly constricted at 19 2/3 days but not at 19 1/2 days. Higher doses of indomethacin (10 and 100 mg/kg) induced a significant constriction of the DA at day 19 1/2, but not at the beginning of the same day (1.00 a.m.). These results suggest that the onset of the susceptibility of the DA to the constrictive effect of indomethacin occurs in the first half of day 19 of gestation.     

Endothelin-3 stimulates production of endothelium-derived nitric oxide via phosphoinositide breakdown.

Cultured bovine endothelial cells (EC) have specific receptors for endothelin (ET)-3 functionally coupled to phosphoinositide breakdown. We studied whether ET-3 stimulates synthesis of nitric oxide (NO), an endothelium-derived relaxing factor that activates soluble guanylate cyclase in EC, and whether the ET-3-induced NO formation involves G-proteins. ET-3 dose-dependently stimulated production of intracellular cGMP in EC, of which effects were abolished by pretreatment with NG-monomethyl L-arginine, an inhibitor of NO synthesis, and methylene blue, an inhibitor of soluble guanylate cyclase. The stimulatory effects of ET-3 on cGMP production, inositol trisphosphate formation and increase in cytosolic free Ca2+ concentration were similarly blocked by pretreatment with pertussis toxin (PTX). These data suggest that ET-3 induces synthesis of NO mediated by phosphoinositide breakdown via PTX-sensitive G-protein in EC.     

Effects of 1,25-dihydroxyvitamin D3 and its analogs on butyrate-induced differentiation of HT-29 human colonic carcinoma cells and on the reversal of the differentiated phenotype

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) greatly enhances sodium butyrate (NaB)-induced enterocyte differentiation of HT-29 human colonic carcinoma cells while 1,25-(OH)2D3 alone induces growth restriction without associated differentiation. In the present study, the efficacies of various analogs of 1,25-(OH)2D3 to enhance NaB-induced HT-29 differentiation and to prolong the reversal of the differentiated phenotype under NaB-free growth conditions were subsequently examined. Extent of HT-29 differentiation was assessed by measurement of alkaline phosphatase (AP) activity, appearance of mucin-producing cells, changes in morphological characteristics, and expression of differentiation-associated cytokeratin proteins. Among active analogs of 1,25-(OH)2D3, 26,26,26,27,27,27-hexafluoro-1,25-(OH)2D3 (F6-1,25-(OH)2D3), 24,24-difluoro-24-homo-1,25-(OH)2D3, and 26,27-dimethyl-1,25-(OH)2D3 were 100-, 10-, and 5-fold, respectively, more effective than 1,25-(OH)2D3 in enhancing NaB-induced mucin production. Combined use of NaB and F6-1,25-(OH)2D3 (10(-9) M) also induced HT-29 cells to form highly differentiated goblet-like enterocytes, and increased both cellular AP enzymatic activity and tissue-type cytokeratin content. This differentiated state was qualitatively more advanced than that achieved by a combination of NaB and 10(-7) M 1,25-(OH)2D3. NaB-mediated HT-29 differentiation (in short-term inductions) was found to be reversible following a return to NaB-free medium. HT-29 cells differentiated by combined use of NaB and 1,25-(OH)2D3 or its analogs exhibited a significant prolonged reversal time relative to cells differentiated with NaB alone. The most prominent effect was achieved using cells differentiated with NaB and 10(-9) M F6-1,25-(OH)2D3 which exhibited a 7-fold prolonged reversal time over colonocytes differentiated by NaB alone. Our data suggest that a combined use of NaB and 1,25-(OH)2D3 or its derivatives may provide a convenient in vitro model system to probe molecular events associated with steroid-target tissue interactions in a differentiating cell system as commonly occurs in vivo. Such an analysis might lend itself to design of a rational combination differentiation-based therapy for the clinical management of colon cancer.