Natural Inhibitor for Volatile C6-Aldehyde Formation from C18-Unsaturated Fatty Acids

The homogenate of tea seed cotyledons contained an inhibitor for C₆-aldehyde formation from linoleic acid and linolenic acid by isolated tea chloroplasts. Seed homogenates of other plants, such as soybean, kidney bean, cucumber, Japanese radish and rice, also contained the inhibitor for C₆-aldehyde formation. The inhibitor from tea seed and cucumber seed inhibited C₆-aldehyde formation by the homogenate of cucumber hypocotyl. Hydroperoxides of linoleic acid detected were reduced when the tea seed inhibitor was added to the reaction mixture, but the enzyme activities of lipoxygenase and hydroperoxide lyase were not inhibited. This means that the inhibitor is a decomposer of fatty acid hydroperoxides as an intermediate of C₆-aldehyde formation. The tea seed inhibitor was formed during the seed ripening and it was stable during the seed germination. These findings obtained here suggest that the inhibitor is widely present in plant seeds and inhibits C₆-aldehyde formation by a variety of plant tissues.     

AHNAK, a protein that binds and activates phospholipase C-gamma1 in the presence of arachidonic acid.

We have recently shown that phospholipase C-gamma (PLC-gamma) is activated by tau, a neuronal cell-specific microtubule-associated protein, in the presence of arachidonic acid. We now report that non-neuronal tissues also contain a protein that can activate PLC-gamma in the presence of arachidonic acid. Purification of this activator from bovine lung cytosol yielded several proteins with apparent molecular sizes of 70-130 kDa. They were identified as fragments derived from an unusually large protein (approximately 700 kDa) named AHNAK, which comprises about 30 repeated motifs each 128 amino acids in length. Two AHNAK fragments containing one and four of the repeated motifs, respectively, were expressed as glutathione S-transferase fusion proteins. Both recombinant proteins activated PLC-gamma1 at nanomolar concentrations in the presence of arachidonic acid, suggesting that an intact AHNAK molecule contains multiple sites for PLC-gamma activation. The role of arachidonic acid was to promote a physical interaction between AHNAK and PLC-gamma1, and the activation by AHNAK and arachidonic acid was mainly attributable to reduction in the enzyme's apparent Km toward the substrate phosphatidylinositol 4,5-bisphosphate. Our results suggest that arachidonic acid liberated by phospholipase A2 can act as an additional trigger for PLC-gamma activation, constituting an alternative mechanism that is independent of tyrosine phosphorylation.     

Synthetic Analogues of the Termite Trail-following Substance

The effect of tripropyltin chloride (TPT) on some functional reactions in E. coli was investigated. The inhibition on respiration and protein, DNA and RNA syntheses were examined in vivo. Oxygen consumption by E. coli cells was scarcely inhibited even at the concentration of 30 µg/ml TPT. The incorporations of ¹⁴C-labeled amino acids into protein fraction were inhibited. Especially, in the case of l-leucine, it was inhibited 60% even at 10 µg/ml TPT. Both incorporations of ¹⁴C-adenine into DNA and RNA fraction were inhibited 50–60% at 20 µg/ml TPT. RNA polymerase was prepared from E. coli cells and the effect of organotin compounds on the enzyme activity was examined. Organotin compounds inhibited the enzyme activity only at high concentrations (5-10mm). and dialkyltin chlorides which possess no antimicrobial action showed the inhibition more intensely than trialkyltin chlorides. The effect on membrane-bound ATPase was also examined in vitro. We found that TPT has high inhibitory action on membrane-bound ATPase. However, it slightly inhibited the activity of ATPase separated from membrane.     

BMP-7 inhibits cartilage degeneration through suppression of inflammation in rat zymosan-induced arthritis

Bone morphogenetic protein-7 (BMP-7) regulates cartilage metabolism and promotes matrix synthesis. However, the effect of BMP-7 on inflammatory arthritis remains unknown. We investigated the effect and mechanism of exogenous BMP-7 on cartilage and synovium in vivo in rat zymosan-induced arthritis. Zymosan was injected into the left knees of Wistar rats. Phosphate-buffered saline or BMP-7 at 10, 100, or 1000 ng per joint was injected into the left knee every 2 days. Normal joints acted as normal controls. The knee joints were analyzed histologically and immunohistologically at 14 days. Joint swelling was evaluated by measuring the transverse diameter of the knee joints. Synovial lysates were collected, and the concentrations of interleukin-1β (IL-1β), IL-6, and IL-10 were measured by enzyme-linked immunosorbent assay. Intra-articular injection of zymosan resulted in acute inflammation and was followed by cartilage degeneration. Local administrations of BMP-7 inhibited this loss of cartilage matrix in a dose-dependent manner. Immunohistochemical analysis demonstrated enhanced type II collagen levels in cartilage and enhanced BMP-7 levels in cartilage and synovium after exogenous BMP-7 treatment. Joint swelling and cell infiltration into synovium were significantly reduced by BMP-7 injections. Administration of BMP-7 decreased IL-1β production significantly and increased IL-10 production in the synovium. Thus, intra-articular injections of BMP-7 had a protective effect on cartilage degeneration in the inflammatory arthritis model by enhancing levels of BMP-7 in cartilage and suppressing the production of IL-1β in synovium.     

Comparative biochemistry of disintegrins isolated from snake venom: consideration of the taxonomy and geographical distribution of snakes in the genus Echis

Species in the genus Echis have been classified mainly based on their morphological appearance and the analytical patterns of their serum. However, re-classification of the genus Echis has recently been suggested by taxonomists, toxicologists, and clinicians, since there have been problems with the current classification, such as the efficacy of antivenoms used for treating bites and the broad geographical distribution of Echis snakes. In this study, we purified five novel disintegrins, the platelet aggregation inhibitors pyramidin A and B from the venom of Echis pyramidum, ocellatin from the venom of Echis ocellatus, and leucogastin A and B from the venom of Echis leucogaster, to compare their sequences and allow us to re-evaluate the classification of various species in the genus Echis. Comparison of the amino acid sequences of five new and four known isolated disintegrins from snake venoms of six Echis species and their distribution strongly support the recent re-classification of the genus Echis.     

Identification of tumor suppressor candidate genes by physical and sequence mapping of the TSLC1 region of human chromosome 11q23

Loss of heterozygosity for a locus on human chromosome 11q22-23 is observed at high frequency in non-small cell lung carcinoma (NSCLC). Introduction of a 1.1 Mb fragmented yeast artificial chromosome (YAC) mapping to this region completely suppresses the tumorigenic properties of a human NSCLC cell line, A549. Smaller fragmented YACs give partial but not complete suppression. To further localize the gene(s) responsible for this partial suppression, a bacterial artificial chromosome (BAC) and P1-based artificial chromosome (PAC) contig was constructed, completely spanning the candidate region. End sequence generated in the construction of the BAC/PAC contig identified a previously unmapped EST and served to order genomic sequence contigs from the publicly available Celera Genomics (CG) and Human Genome Project (HGP) efforts. Comparison showed that CG provided larger contigs, while HGP provided more coverage. Neither CG nor HGP provided complete sequence coverage, alone or in combination. The sequence was used to map 110 ESTs and to predict new genes, including two GenScan gene predictions that overlapped ESTs and were shown to be differentially expressed in tumorigenic and suppressed A549 cell lines.