VENOM COMPONENTS OF Asobara japonica IMPAIR CELLULAR IMMUNE RESPONSES OF HOST Drosophila melanogaster

The endoparasitoid wasp Asobara japonica has highly poisonous venom: the host Drosophila larvae are killed by envenomation at a dose that is naturally injected by the female wasp at parasitism. This insecticidal venom is neutralized, however, because A. japonica introduces lateral oviduct components soon after venom injection at oviposition. Although the venom and lateral oviduct components of this parasitoid have been partially characterized, how the venom components favor successful development of wasp eggs and larvae in the host remains ambiguous. Here, we demonstrated that A. japonica venom did not affect host humoral immune responses, determined as expression of antimicrobial peptide (AMP) genes, but significantly diminished two cellular responses, spreading and phagocytosis, by host hemocytes. Moreover, venom components drastically elevated a serine protease‐like activity 4 h after its injection. The lateral oviduct components did not negate the detrimental effects of the venom on host cellular immunities, but significantly reduced the venom‐induced elevation of protease activity. Both active factors in venom and lateral oviduct components were roughly characterized as heat‐labile substances with a molecular mass of at least 10 kDa. Finally, venom of A. japonica, with a wide host range, was found to be much more toxic than that of Asobara rossica, which has a limited host range. These results reveal that A. japonica venom toxicity allows exploitation of a broader range of host insects because it is essential to overcome cellular immune responses of the host for successful parasitism.     

Isolation of transposon Tn5 mutant affected in the metabolism of 18β-glycyrrhetinic acid

Transposon Tn5 mutagenesis was carried out to clarify the metabolism of 18-glycyrrhetinic acid (18-GRA) in Sphingomonas paucimobilis G5. A Tn5-induced mutant strain, named TM9638 that was affected in its metabolism of 18-GRA, was isolated. This mutant accumulated three metabolites, designated as M-A, M-B and M-C, from 18-GRA in the culture broth. M-A was accumulated in the culture broth of wild type strain, but M-B and M-C were not accumulated in the culture broth of wild type strain. M-B and M-C were isolated from the culture broth of TM9638 and the chemical structures were elucidated by NMR and GC-MS.     

Metabolism of 18β-glycyrrhetinic acid in Sphingomonas paucimobilis strain G5

Seven strains capable of utilizing 18-glycyrrhetinic acid (18-GRA) as a sole carbon and energy source were isolated from soil samples by enrichment culture technique. One of these strains, named strain G5, was identified as Sphingomonas paucimobilis. When this strain grew on 18-GRA, several metabolites were detected in the culture broth. A major metabolite, tentatively named M-A, was isolated and its chemical structure was determined by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS).     

Establishment of cell strains from human urothelial carcinoma and their morphological characterization

We have examined the conditions for cultivation of enzymatically dispersed cells from 34 human urothelial transitional cell carcinomas (TCC) of various types. By employing two culture methods, stationary and tapping suspension, and by using the synthetic medium DM 160 supplement with human umbilical cord serum and fetal bovine serum, six cell strains were established. In two strains the tapping suspension culture method was suitable for growth of highly malignant cancer cells that detach easily from the glass surface in stationary cultures. Each of the six cell strains has been maintained in culture for over 30 months with repeated subcultures of 32 to 128 times. The histopathological features of the original TCC were three differentiated papillary types and three anaplastic nonpapillary types. In two cell strains from TCC with low malignancy, however, the cancer masses that formed in nude mice differed from the original TCC in which they became more malignant, and one cell strain resembled the original TCC closely. In three stationary culture cell strains the epithelial nature was demonstrated by the presence of desmosomes and tonofilaments. In one cell strain only tonofilaments were present. In two tapping suspension culture cell strains the presence of desmosomes was not shown clearly, but fine tonofilaments were observed in one cell strain.     

The Structures of Cirratiomycin A and B,the New Peptide Antibiotics

The structures of cirratiomycin A and B have been elucidated by a degradative study and ¹H-and ¹³C-NMR spectral analysis. It is revealed here that cirratiomycin A and B are heptapeptides containing three unusual new amino acids, viz, hydroxymethylserine, 2,3,4,5-tetrahydropyridazine-3-carboxylic acid and 2,3-didehydroisoleucine.     

Remodeling of the Rad51 DNA Strand-Exchange Protein by the Srs2 Helicase

Homologous recombination is associated with the dynamic assembly and disassembly of DNA–protein complexes. Assembly of a nucleoprotein filament comprising ssDNA and the RecA homolog, Rad51, is a key step required for homology search during recombination. The budding yeast Srs2 DNA translocase is known to dismantle Rad51 filament in vitro. However, there is limited evidence to support the dismantling activity of Srs2 in vivo. Here, we show that Srs2 indeed disrupts Rad51-containing complexes from chromosomes during meiosis. Overexpression of Srs2 during the meiotic prophase impairs meiotic recombination and removes Rad51 from meiotic chromosomes. This dismantling activity is specific for Rad51, as Srs2 Overexpression does not remove Dmc1 (a meiosis-specific Rad51 homolog), Rad52 (a Rad51 mediator), or replication protein A (RPA; a single-stranded DNA-binding protein). Rather, RPA replaces Rad51 under these conditions. A mutant Srs2 lacking helicase activity cannot remove Rad51 from meiotic chromosomes. Interestingly, the Rad51-binding domain of Srs2, which is critical for Rad51-dismantling activity in vitro, is not essential for this activity in vivo. Our results suggest that a precise level of Srs2, in the form of the Srs2 translocase, is required to appropriately regulate the Rad51 nucleoprotein filament dynamics during meiosis.     

Histochemical demonstration of aluminum and iron deposition in pulmonary bony tissues in three cases of diffuse pulmonary ossification

Diffuse pulmonary ossification is a rare condition. We examined three cases of it in Japan, and attempted histochemically to stain for deposition of aluminum and iron in bony tissues. The patients were all female, and in their mid-twenties, mid- eighties, and later teen years. One of the patients had been exposed to heavy metals in her work involving heavy-metal analyses for 18 months. Aluminum staining and Berlin blue staining for iron were performed with dewaxed, undecalcified sections of pulmonary tissues from these three cases. Interestingly, all pulmonary bony tissues from the three cases examined exhibited linear regions of both aluminum and iron deposition in the calcifying fronts or the cement lines of bones. The patient exposed to heavy metals exhibited the most severe aluminum and iron deposition, and also exhibited positive reaction for both aluminum and iron in elastic fibers of blood vessels. Foreign body granulomas with multinucleated giant cells exhibiting elastophagia were also found in this case. This phenomenon, "endogenous pneumoconiosis", appeared to have been the cause of pulmonary hemorrhage in this case, resulting in focal heavy hemosiderosis. It is of great interest that identical patterns of aluminum and iron deposition in hemodialysis patients were found in these three cases, This is the first report on histochemical demonstration of aluminum and iron deposition in diffuse pulmonary ossification, and detailed analysis of additional cases is needed.     

Identification of novel metabolites in the degradation of phenanthrene by Sphingomonas sp. strain P2

Sphingomonas sp. strain P2, which is capable of utilizing phenanthrene as a sole carbon and energy source, was isolated from petroleum-contaminated soil in Thailand. Gas chromatography-mass spectrometry and (1)H and (13)C nuclear magnetic resonance analyses revealed two novel metabolites from the phenanthrene degradation pathway. One was identified as 5,6-benzocoumarin, which was derived by dioxygenation at the 1- and 2-positions of phenanthrene, and the other was determined to be 1,5-dihydroxy-2-naphthoic acid. Other metabolites from phenanthrene degradation were identified as 7, 8-benzocoumarin, 1-hydroxy-2-naphthoic acid and coumarin. From these results, it is suggested that strain P2 can degrade phenanthrene via dioxygenation at both 1,2- and 3,4-positions followed by meta-cleavage.     

Hypomethylation and expression of pepsinogen A genes in the fundic mucosa of human stomach

We have examined the correlation between the extents of methylation and expression of pepsinogen A genes in normal human tissues. Expression of pepsinogen A mRNA was detected only in the fundic mucosa of the stomach and both CCGG and GCGC sites in the genes region were less methylated in the fundic mucosa than in other non-expressing tissues. Thus, there was an inverse correlation between the extents of methylation and expression of pepsinogen A genes and the role of DNA methylation in the regulation of pepsinogen A genes expression during normal differentiation was suggested.