Interleukin-5 induces tumor suppression by peritoneal exudate cells in mice

The antitumor activity of peritoneal exudate cells (PEC) induced by murine interleukin-5 (mIL-5) was examined using Meth-A sarcoma cells transplanted into the peritoneal cavity of mice. Although in vitro treatment of Meth-A sarcoma cells with mIL-5 did not result in inhibition of their growth, treatment of mice intraperitoneally with mIL-5 (1 g/day) from day –5 to +5 (tumor cells were inoculated on day 0) led to a significant increase in survival or even rejection of tumor cells. This antitumor effect depended on the dose of mIL-5. Interestingly, there was identical therapeutic activity when the protocol of days –10 to –1 was used as opposed to –5 to +5. In addition, post-treatment with mIL-5 from day +1 to +10 was ineffective. This suggests that the therapeutic activity of IL-5 is largely prophylactic. Under the former condition, the number of PEC was found to increase over 50-fold when compared to levels in control mice. Moreover, the antitumor effect of mIL-5 was completely abolished by subcutaneous injection of anti-mIL-5 monoclonal antibodies. The treatment of mice injected intraperitoneally with human IL-2 also resulted in an increase in survival. Winn assay experiments using PEC recovered from mIL-5-treated mice (1g/day, from day –10 to –1) revealed that these PEC could mediate antitumor activity against Meth-A sarcoma cells. Furthermore, when the cured mice were re-injected with Meth-A sarcoma cells or syngeneic MOPC 104E cells, they could reject Meth-A sarcoma cells but not MOPC 104E cells, indicating that immune memory had been generated. These results suggest that IL-5 augumented the PEC tumoricidal activity but we have no indication that the tumoricidal activity was mediated through a mIL-5-dependent mechanism.     

Seed dispersal and vegetation development on a debris avalanche on the Ontake volcano,Central Japan

Seed dispersal and early revegetation processes were studied in an area devastated by a debris avalanche that occurred on volcano Ontake, Central Japan in 1984. The avalanche was initiated by a volcanic earthquake, and a 3.4 x 10⁷ m³ land mass destroyed the vegetation over 700 ha. The revegetation of the first five years was slow in the area of higher elevation (subalpine area). Both the speed of revegetation and the species richness of trapped seeds varied with the elevation. The post-disturbance vegetation on the deposit with surface soil or plant fragments was richer in species than that without any surface soil. Almost all of the seeds caught by sticky traps and most of the species with frequent occurrence in the vegetation after disturbance were wind dispersed. Wind dispersal was especially important on the deposit without surface soil or plant fragments.     

Fatty acyl-CoA binding activity of the nuclear thyroid hormone receptor

Long-chain fatty acids and their acyl-CoA esters are potent inhibitors of nuclear thyroid hormone (T₃) receptor in vitro. In the present study, we obtained evidence for acyl-CoA binding activity in the nuclear extract from rat liver. The activity sedimented at a position (3.5 S) identical with that of the T₃ receptor, and the two activities sedimented together. Similarly, they coeluted on DEAE-Sephadex. After partial purification of the receptor, it was again inhibited strongly by acyl-CoAs. Heat stability and a partial trypsin digestion of the receptor both suggested that the action site of oleoyl-CoA overlapped the T₃-binding domain of the receptor. In addition, thyroid hormone receptor β1, synthesized in vitro, bound oleoyl-CoA specifically and its T₃-binding activity was inhibited. The dissociation constant for oleoyl-CoA binding to the partially purified receptor was 1.2 × 10^?7 M. This value as well as its molecular size distinguished the nuclear binding sites from the cytoplasmic fatty acid/acyl-CoA binding proteins. Oleoyl-CoA had no effect on the glucocorticoid receptor, another member of the nuclear hormone-receptor superfamily. From these results, we propose that thyroid hormone receptor is a specific acyl-CoA binding protein of the cell nucleus.     

Regulation of L-alanine-initiated germination ofBacillus subtilis spores by alanine racemase

Summary Germination ofBacillus subtilis spores was initiated by L-Ala and competitively inhibited by D-Ala, suggesting the presence of an alanine receptor. The spores showed alanine racemase activity in the spore coat. To investigate the role of alanine racemase (L D) on germination, net racemase activity was determined using diphenylamine as a germination inhibitor and germination was measured using D-penicillamine as a racemase inhibitor. Apparent affinity of L-Ala to the germinant receptor was more than 1000 times higher than that to the racemase. Germination increased in the presence of D-penicillamine, when the concentration of L-Ala was low and that of spores was high. Racemase activity was optimal at 65°C at pH 9.0 and germination at 43°C at pH 7.2. Under unfavorable growth conditions such as high population of spores in limited nutrients, high temperature and high pH, spore alanine racemase converted the germinant actively to the inhibitor and this conversion may regulate germination for survival of the population.     

Variations in and Inheritance of NS-Glycoprotein in Self-Incompatible Brassica campestris L.

The stigma of Brassica species contain NS-glycoproteins thatexhibit a high degree of structural homology to the S-glycoproteinsof self-incompatibility. Inheritance of and variations in theNS-glycoprotein were studied with reference to self-incompatibility.The detection of NS-glycoproteins was performed by cross-reactionwith an antiserum raised against a purified NS-glycoprotein.In B. campestris, four isoforms of the NS-glycoprotein weredifferentiated by their pI values, but their molecular weightswere identical to one another. The genes for these isoformsof NS-glycoprotein were controlled by alleles at a single locus,tentatively named the NS allele, which was independent of Salleles at both the protein and the DNA level. Segregation ofF₂ plants with respect to the self-incompatibility behaviorof pollen tubes can be explained by the S allele model, butit appears not to be affected by the NS alleles. NS-glycoproteinswere found in all 21 species of Brassica and its allies examinedto date. The pI values of these glycoproteins varied among differentspecies. In addition to the isoforms of the NS alleles, maturestigmas contained other groups of proteins that reacted weaklywith the antiserum against the NS-glycoprotein. (Received July 30, 1991; Accepted February 21, 1992)     

Response of Japanese beech (Fagus japonica Maxim.) sprouts to canopy gaps

The response of Japanese beech (Fagus japonica Maxim.) sprouts to canopy gaps in natural beech forest in central Japan was studied using two contrasted gaps in which tree-ring chronologies of regenerating stems were analyzed. The gaps were created by uprooting of a single Quercus mongolica var. grosseserrata stem (diameter: 50 cm; gap size: 40 m²; 23 years old) and by concurrent uprootings of four F. japonica stools (gap size: 180 m²; 30 years old). Japanese beech sprouts emerged before and after the gap formation and dominated stem populations in both gaps. In gaps, growth of F. japonica sprouts was equal or lower than growth of stems of seed origin, but most sprouts (F. japonica, Acer mono var. marmoratum) appeared a few years before emergence of seedlings. The small gap created by single stem fall was dominated by some beech sprouts from stools adjacent to the gap. The multiple gap was not closed by beech sprouts from stools surrounding the gap, but some dominant beech stems were resprouts from the uprooted beech stools. The existence of a sprout bank under the canopy may play an important role in the closing process of gaps in natural Japanese beech forest.     

PLD activation in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA

Pertussis toxin-insensitive GTP-binding protein was observed to be involved in prostaglandin F2α(PGF2α)-induced phosphoinositide metabolism in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA (CHO-PGF2α·R cells) (Ito, S. et al. Biochem. Biophys. Res. Commun. 200: 756, 1994). In the present study, we investigated PGF2α-induced PLD activation in CHO-PGF2α·R cells. PLD activation was examined by measuring the production of [³H]phosphatidylbutanol ([³H]PBut), a specific product of the PLD-catalyzed transphosphatidylation reaction. PGF2α-induced [³H]PBut formation was concentration-dependent with the maximal level obtained at 1 μM PGF2α. The maximal [³H]PBut formation was observed at 2 min after addition of PGF2α. Depletion of extracellular Ca²⁺ with EGTA suppressed PGF2α-induced PLD activation by 50%. PKC inhibitors Ro31–8425 and calphostin C inhibited PGF2α-induced [³H]PBut formation by 50%. PTK inhibitors genistein and herbimycin A failed to inhibit PGF2α-induced PLD activation. A combination of maximal effective concentrations of PGF2α (1 μM) and PMA (100 nM) enhanced PLD activation in an additive manner. Pretreatment of the cells with PMA for 2 h down-regulated PKCα and decreased PGF2α-induced PLD activation. These results suggest that PLD activation by PGF2α is mediated by both PKC-dependent and -independent pathways and that PKCα is involved in the former pathway.     

Relationship between actions of transforming growth factor (TGF)-β and cell surface expression of its receptors in clonal osteoblastic cells

Various osteoblastic cell lines were examined for the relationship between the presence of cell-surface transforming growth factor (TGF)-β receptors and the synthesis of matrix proteins with their responsiveness to TGF-β. Treatment with TGF-β1 inhibited proliferation and stimulated proteoglycan and fibronectin synthesis in MC3T3-E1 and MG 63 cells. The major proteoglycans synthesized by these cells were decorin and biglycan, and TGF-β1 markedly stimulated the synthesis of decorin in MC3T3-E1 and of biglycan in MG 63 cells. SaOS 2 and UMR 106 cells synthesized barely detectable amounts of decorin or biglycan, and TGF-β1 did not stimulate the synthesis of these proteoglycans. In SaOS 2 cells, however, TGF-β1 enhanced fibronectin synthesis. TGF-β1 did not show any of these effects in UMR 106 cells. Receptor cross-linking studies revealed that only MC3T3-E1 and MG 63 cells had both types I and II signal-transducing receptors for TGF-β in addition to betaglycan. SaOS 2 cells possessed type I but no type II receptor on the cell surface. In contrast, SaOS 2 as well as MC3T3-E1 and MG 63 cells expressed type II receptor mRNA by Northern blot analysis, and cell lysates contained type II receptor by Western blot analysis. Thus, it appears that type II receptor present in SaOS 2 cells is not able to bind TGF-β1 under these conditions. UMR 106 cells with no response to TGF-β1 had neither of the signal-transducing receptors by any of the analyses. These observations using clonal osteoblastic cell lines demonstrate that the ability of osteoblastic cells to synthesize bone matrix proteoglycans is associated with the responsiveness of these cells to TGF-β1, that the responsiveness of osteoblastic cells to TGF-β1 in cell proliferation and proteoglycan synthesis correlates with the presence of both types I and II receptors, and that the effect of TGF-β1 on fibronectin synthesis can develop with little binding of TGF-β1 to type II receptor if type I receptor is present. It is suggested that the combination of cell-surface receptors for TGF-β determines the responsiveness of osteoblastic cells to TGF-β and that changes in cell-surface TGF-β receptors may play a role in the regulation of matrix protein synthesis and bone formation in osteoblasts. © 1995 Wiley-Liss, Inc.     

In vitro neurotoxicity of amyloid β-peptide cross-linked by transglutaminase

Transglutaminase catalyzes the intermolecular cross-linking of peptides between Gln and Lys residues, forming an -(-glutamyl) lysine bond. Amyloid -peptide, a major constituent of the deposits in Alzheimer disease, contains Lys16, Lys28, and Gln15 which may act as substrates of transglutaminase. Transglutaminase treatment of amyloid -peptide (1–28) and amyloid -peptide (1–40) yielded cross-linked oligomers. Transglutaminase-treated A retarded neurite extension of PC12 cells, and rat cultured neurons of hippocampus and septum, brain areas severely affected by Alzheimer disease, and subsequently caused cell death, whereas the transglutaminase-untreated counterparts did not show harmful effects. The transglutaminase-catalyzed oligomers of amyloid -peptide and their neurotoxicity may be involved in two characteristics in Alzheimer disease, neuronal degeneration and formation of the insoluble deposits.Abbreviations: AD – Alzheimer disease, A – amyloid -peptide, DMEM – Dulbecco's modified Eagle's medium, DMEM/F–12–1:1 mixture of DMEM and Ham's F–12 medium, FCS – fetal calf serum, HS – horse serum, PAGE – polyacrylamide gel electrophoresis, MTT – 3-(4,5-dimethylthiazol–2-yl)–2,5-diphenyltetrazolium bromide, NGF – nerve growth factor, TGase – transglutaminase.