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Introduction of genetic material into cells is an essential prerequisite for current research in molecular cell biology. Although transfection with commercially available reagents results in excellent gene expression, their high costs are obstacles to experimentation with a large number or large scales of transfection. The cationic polymer linear-polyethylenimine (MW 25,000) (PEI), one of the most cost-effective vehicles, facilitates DNA compaction by polyplex formation, which leads to efficient delivery of DNA into cells by endocytosis. However, the use of PEI is still limited because of substantial cytotoxicity and intolerable deterioration in transfection efficiency by its low stability. Here, we show that acidification of PEI is important for its transfection activity. Dissolving PEI powder in 0.2N HCl confers a long shelf-life for PEI storage at 4 and -80 degrees C, and the polyplex formation of plasmid DNA with PEI is optimized in lactate-buffered saline at pH 4.0. Furthermore, changing the culture medium at 8-12 h posttransfection can minimize the cytotoxicity of PEI without sacrificing the high transfection efficiency comparable to that of commercial reagents. The cost per test using acidified PEI is drastically reduced to approximately 1:10,000, compared with commercial reagents. Thus, we conclude that acidification of PEI satisfactorily accomplishes cost-effective, high-efficiency transfection.

Polyploid cells result in aneuploidy through aberrant chromosome segregation, possibly leading to tumorigenesis. Although polyploid cells are induced through over-replication by a variety of agents, including DNA-damaging drugs, the mechanisms that induce polyploidy have been hitherto unknown. Here, we show that treatment with bleomycin, a glycopeptide anticancer drug, induces over-replication at low cytotoxic doses. During bleomycin-induced over-replication, mitotic entry is inhibited through tyrosine phosphorylation of CDK1 along the ATM/ATR pathway in the early phase of treatment. Bleomycin-induced over-replication is inhibited by the inhibitors of the ATM/ATR pathway through abrogation of bleomycin-induced G2 arrest, and the ATM/ATR inhibitors promote cell death instead of over-replication. Following the phosphorylation of CDK1, the level of cyclin B1 is decreased in the late phase of treatment. Time-lapse imaging of clone cells that express a live cell marker of endogenous cyclin B1 revealed that cyclin B1 is degraded in G2-arrested cells upon bleomycin treatment. Our findings lead to a model of how the ATM/ATR pathway acts as a molecular switch for regulating cell fates, flipping between cell death via progress into mitosis, and over-replication via sustained G2 arrest upon DNA damage, where cyclin B1 degradation is an important factor for inducing over-replication.

1H- and 3H-Cyclopent[a]azulenes having an electron withdrawing group, such as a methoxycarbonyl or a cyano group, at the 9-position were synthesized from their dihydro compounds by means of bromination with NBS and succeeding dehydrobromination by refluxing in chloroform. Base-catalyzed condensation of these cyclopent[a]azulenes with carbonyl compounds afforded 1-methylene-1H- and 3-methylene-3H-cyclopent[a]azulene derivatives having an electron withdrawing group at the 9-position. The physical properties of these methylenecyclopent[a]azulenes are also discussed.

The cycloaddition reaction of 3-methoxycabonyl-2H-cyclohepta[b]furan-2-one with 6,6-dimethylfulvene was carried out under refluxing in ethanol, benzene, or xylene. The [4+2] cycloadduct was formed as a major product in ethanol or benzene together with the minor [8+2] cycloadduct. On the other hand, the [8+2] cycloadduct was formed as a single product in xylene. The [4+2] cycloadduct was completely changed to the [8+2] cycloadduct under refluxing in xylene by a retro–Diels–Alder reaction, a re-cycloaddition reaction followed by spontaneous decarboxylation. The structure of the [8+2] cycloadduct was clearly confirmed by chemical transformation to methyl 3-isopropyl-1H-cyclopent[a]azulene-9-carboxylate which was obtained by the hydride reduction of methyl 3-isopropylidene-3H-cyclopent[a]azulene-9-carboxylate.

1H- and 3H-Cyclopent[a]azulenes having an electron withdrawing group, such as a methoxycarbonyl or a cyano group, at the 9-position were synthesized from their dihydro compounds by means of bromination with NBS and succeeding dehydrobromination by refluxing in chloroform. Base-catalyzed condensation of these cyclopent[a]azulenes with carbonyl compounds afforded 1-methylene-1H- and 3-methylene-3H-cyclopent[a]azulene derivatives having an electron withdrawing group at the 9-position. The physical properties of these methylenecyclopent[a]azulenes are also discussed.

Adriamycin, an anthracycline antibiotic, has been used for the treatment of various types of tumours. Adriamycin induces at least two distinct types of growth repression, such as senescence and apoptosis, in a concentration-dependent manner. Cellular senescence is a condition in which cells are unable to proliferate further, and senescent cells frequently show polyploidy. Although abrogation of cell division is thought to correlate with polyploidization, the mechanisms underlying induction of polyploidization in senescent cells are largely unclear. We wished, therefore, to explore the role of cyclin B1 level in polyploidization of Adriamycin-induced senescent cells. A subcytotoxic concentration of Adriamycin induced polyploid cells having the features of senescence, such as flattened and enlarged cell shape and activated beta-galactosidase activity. In DNA damage-induced senescent cells, the levels of cyclin B1 were transiently increased and subsequently decreased. The decrease in cyclin B1 levels occurred in G2 cells during polyploidization upon treatment with a subcytotoxic concentration of Adriamycin. In contrast, neither polyploidy nor a decrease in cyclin B1 levels was induced by treatment with a cytotoxic concentration of Adriamycin. These results suggest that a decrease in cyclin B1 levels is induced by DNA damage, resulting in polyploidization in DNA damage-induced senescence.

The cycloaddition reaction of 3-methoxycabonyl-2H-cyclohepta[b]furan-2-one with 6,6-dimethylfulvene was carried out under refluxing in ethanol, benzene, or xylene. The [4+2] cycloadduct was formed as a major product in ethanol or benzene together with the minor [8+2] cycloadduct. On the other hand, the [8+2] cycloadduct was formed as a single product in xylene. The [4+2] cycloadduct was completely changed to the [8+2] cycloadduct under refluxing in xylene by a retro–Diels–Alder reaction, a re-cycloaddition reaction followed by spontaneous decarboxylation. The structure of the [8+2] cycloadduct was clearly confirmed by chemical transformation to methyl 3-isopropyl-1H-cyclopent[a]azulene-9-carboxylate which was obtained by the hydride reduction of methyl 3-isopropylidene-3H-cyclopent[a]azulene-9-carboxylate.

3H-Cyclopent[a]azulen-3-one and two methyl derivalives, which have a new tricyclic π-conjugated system, were synthesized starting from 9-methoxycarbonyl-1,2-dihydro-3H-cyclopent[a]azulen-3-one by the application of flash vacuum pyrolysis in the final step. All proton signals of these compounds were observed at higher fields than those of the referenced 1,2-dihydro compound, but there are no significant differences between the carbon magnetic resonances of 3H-cyclopent[a]azulen-3-ones and the reference compound. These high field shifts on 1H NMR were appreciated in terms of an induced paramagnetic ring current caused by the contribution of a 12-π electron system in the periphery of this molecule. 3H-cyclopent[a]azulen-3-one was stable in the crystalline state, but gradually changed in solution to a hexacyclic compound by decarbonylative dimerization, while the 2-methyl derivative was very stable both in the crystalline state and in solution. Although the reaction of 3H-cyclopent[a]azulen-3-one with cyclope...

1H- and 3H-cyclopent[a]azulene were synthesized in excellent yields by applying flash vacuum pyrolysis. Their structures were clearly determined. A mixture of 1H- and 3H-cyclopent[a]azulene was completely anionized with methyllithium in THF, but 67% so in ether. Although 1H-cyclopent[a]azulene reacted with dichloroketene to give a [2+2] cycloadduct, 3H-cyclopent[a]azulene reacted with cyclopentadiene to give a [4+2] cycloadduct. These chemical behaviors were predictable according to HMO theory.

Human magphinin proteins are translation products of differentially spliced transcripts from the 5' region of the human trophinin gene (TRO), whose 3' region encodes trophinin, a unique cell adhesion molecule involved in human embryo implantation. Magphinins belong to the MAGE (melanoma-associated antigen) family, and a previous study of mouse magphinins showed their expression in male and female germ cells, suggesting a role in germ cell development. Here, we characterized the structure and subcellular localization of human magphinins. Confocal microscopy analysis of ectopically expressed magphinins revealed that magphinin-alpha and -beta localize in the cytoplasm, whereas magphinin-gamma lacking the peptide encoded by exon-3 is nuclear. Following Triton X-100 extraction, DNA digestion, and high salt extraction magphinin-gamma remained nuclear, suggesting strong association with the nuclear matrix. A series of magphinin-gamma deletion mutants were generated and assayed for localization, which showed that the N-terminal region of the MAGE homology domain is necessary for nuclear localization. When magphinin-gamma was expressed in NIH3T3 cells, cells underwent G1 arrest. These results suggest that human magphinin-gamma inhibits cell cycle progression through nuclear activity.