Differentiation of a histiocytic lymphoma cell line by lipomodulin,a phospholipase inhibitory protein

When U 937 cells, a human histiocytic lymphoma cell line, were cultured with purified lipomodulin for 3 days, morphological and functional differentiation was induced as detected by microscopical examination of Giemsa stained smears, expression of mature monocyte antigen, and antibody dependent cellular cytotoxicity tests. Essentially similar differentiation was observed by the treatment with dexamethasone for 6 days and this differentiation by dexamethasone was blocked by monoclonal anti-lipomodulin antibody. Furthermore, the synthesis of immunoprecipitable lipomodulin in these cells was induced by dexamethasone treatment. These results, taken together, suggest that the induction of lipomodulin synthesis might be the primary event in dexamethasone-induced cellular differentiation of U 937 cells.     

Agromonas oligotrophica gen. nov., sp. nov., a nitrogen-fixing oligotrophic bacterium

Phenotypic and chemotaxonomic characteristics of five isolates of acetylenereducing (nitrogen-fixing) oligotrophic bacteria from a paddy soil were investigated. They showed similar phenotypic characteristics: they were aerobic, asporogenous, gram-negative, motile by a polar flagellum, and irregular rods. On full strength nutrient broth (NB) growth was severely suppressed, but well supported on 10-to 10000-fold diluted NB. They consumed glucose but produced no acid, and also utilized phenolic acids such as ferulic acid or p-coumaric acid. The cellular fatty acid composition, quinone system and DNA base composition of the isolates were investigated. Cellular fatty acids mainly consisted of straightchain unsaturated C_{18 : 1} (62–81% of total fatty acids). Ubiquinone Q-10 and a high guanine-plus-cytosine content (65.1–66.0 mol%) were found. The taxonomic status of the isolates is discussed and a new genus, Agromonas, with a single species Agromonas oligotrophica sp. nov., is proposed for these isolates. The type strain of A. oligotrophica is JCM 1494.     

Estimates of Denitrification and Nitrification in Coastal and Estuarine Sediments

Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a ¹⁵N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N₂ evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of nitrifying bacteria in the sediments. At Tama Estuary, the nitrate reduction rate was 11 to 17 times higher than the nitrification rate, and nitrogenous oxides derived from ammonium accounted for only 6 to 9% of the N₂ evolution by denitrification.     

Stable and unstable phase of memory in classically conditioned fly, Phormia regina: Effects of nitrogen gas anaesthesia and cycloheximide injection

This study examined the effects of nitrogen anaesthesia and cycloheximide injection on memory of the classically-conditioned fly, Phormia. 1 M NaCl solution was given to each fly as a conditioning stimulus and 0.5 M sucrose solution was the unconditioned stimulus that induced the proboscis extension response. The training period was as short as 2 min and testing was usually carried out 2 hr later. At varying times (0–60 min) between training and testing, flies were anaesthetized with nitrogen gas for 25 sec. When flies were anaesthetized immediately after training the effect of nitrogen gas was the greatest and few flies showed any conditioned response, but the sensitivity of memory to nitrogen gas declined as the interval between training and nitrogen treatment became longer, and such treatment had no effect on memory when the interval was longer than 30 min. The effect on memory of cycloheximide, an inhibitor of peptide bond synthesis, was also investigated. The injection of cycloheximide (0.37 μg) immediately after training diminished the memory, but when given 1 hr after training it had no effect on memory. These results show that the memory in Phormia has two phases, stable and an unstable phase, like long-term and short-term memory in vertebrates.     

Evidence that cyclic AMP may regulate Ca2+-mobilization and phospholipases in thrombin-stimulated human platelets

The regulation of human platelet responses by cyclic AMP (cAMP) has been investigated by measuring thrombin-stimulated serotonin release, Ca²⁺ uptake and phospholipase activity. Thrombin-induced 1,2-diacylglycerol (DG) formation as a result of phospholipase C activation was inhibited by pretreatment with dibutyryl cAMP (dbcAMP) in a dose-dependent manner. Subsequent failure to produce phosphatidic acid (PA), which is converted from 1,2-DG by phosphorylation and would serve as intracellular Ca²⁺ ionophore, appeared to parallel the decrease in Ca²⁺ uptake activity. Phospholipase A₂ activity, monitored by the production of [³H]lysophosphatidylcholine and [³H]lysophosphatidylethanolamine, was also suppressed by dbcAMP. These data indicate that the intracellular cAMP level may be closely associated with Ca²⁺ uptake and phospholipases activation. In addition, it is suggested that alteration of intracellular cAMP regulates phospholipase activation and consequently platelet responses, perhaps by controlling available Ca²⁺ content.     

IL-7 promotes thymocyte proliferation and maintains immunocompetent thymocytes bearing alpha beta or gamma delta T-cell receptors in vitro: synergism with IL-2

IL-7 induced the proliferation of normal thymocytes and the effect was synergistically potentiated by a small dose of IL-2, which by itself hardly affected thymocyte proliferation. No synergism was observed between IL-7 and any one of the other lymphokines including IL-1, IL-3, and IL-4. The thymocyte culture stimulated with IL-7 and IL-2 consisted of single positive (CD4+CD8- and CD4-CD8+) and double negative (CD4-CD8-) populations, and double positive (CD4+CD8+) cells were completely deleted. Both single positive and double negative thymocytes expressed CD3, but only the former exhibited V beta 8 and V beta 6 in an expected proportion (approximately 30% in BALB/c mice) and the latter none at all. Immunoprecipitation of the cultured thymocytes by anti-TCR gamma antibody, on the other hand, revealed the presence of a TCR gamma chain. Taken together, these results indicated that the thymocyte cultured with IL-7 and IL-2 consisted of mature T cells bearing alpha beta or gamma delta TCR. Experiments using preselected thymocyte subpopulations indicated that double negative cells responded to both IL-7 and IL-2 with positive synergism when combined, while thymocytes enriched for single positive cells preferentially responded to IL-7 with little response to IL-2 and no detectable synergism. Double positive thymocytes showed no proliferation in response to IL-7 and IL-2. In contrast to single positive thymocytes, splenic T cells hardly responded to IL-7, although significant proliferation was induced in the presence of a low dose of IL-2. Thymocytes cultured with IL-7 and IL-2 showed little nonspecific cytotoxic activity, but responded to Con A or alloantigen, whereas those stimulated with a high dose of IL-2 alone exhibited potent cytotoxic activity. These results indicated that IL-7 was involved in the generation of immunocompetent T cells in the thymus in concert with IL-2.     

Structure and expression of cDNA for calphobindin II, a human placental coagulation inhibitor

Calphobindin II, with Mr 73,000, is one of the human placental anticoagulant proteins. The cDNA encoding calphobindin II was obtained by screening a human placental lambda gt11 cDNA library using a specific antibody as a probe. The longest cDNA insert consisted of 2,361 nucleotides and a 64-nucleotide-long poly(A) tract. An open reading frame encoding 673 amino acids was predicted. The deduced sequence includes an 8-fold repeat of a conserved 70-amino-acid-long segment that has a high degree of sequence identity with the repeated segments in members of the Ca2+-dependent phospholipid binding protein family. The cDNA fragment including the open reading frame was introduced into the expression vector pKK223-3 and subsequently expressed in Escherichia coli JM105 cells. The resulting recombinant protein reacted with the specific monoclonal antibodies to calphobindin II and prolonged the blood coagulation time as did placental calphobindin II.     

Isolation and characterization of an anticoagulant protein from human placenta

An anticoagulant protein was purified from the EDTA extract of human placental tissue. The purified protein had a molecular weight of 73,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis under both reducing and non-reducing conditions. Because this protein had the ability to bind phospholipids such as phosphatidylserine, phosphatidylinositol, and cardiolipin in the presence of Ca2+, this protein was designated as calphobindin II (CPB-II). CPB-II prolonged the clotting time of normal plasma when coagulation was induced by tissue factor, cephalin and ellagic acid or recalcification, but did not affect thrombin-initiated fibrin formation. CPB-II also inhibited the activation of prothrombin by the complete prothrombinase complex or factor Xa-phospholipid-Ca2+ but not that by phospholipid-free factor Xa. In addition, CPB-II had an inhibitory activity against phospholipase A2.