Caffeine inhibition of postreplication repair of UV-damaged DNA in mouse epidermal cells

The effect of caffeine (0.25–1.5 mM) on UV-irradiated (5 and 10 J/m²) primary cultures of mouse epidermal cells (EPD) and an in vitro transformed cell line (PDV) was studied at the cellular and molecular levels. A synergistic reduction in cell survival induced by caffeine with UV-irradiation was found in the PDV cells at 10 J/m² but not at 5 J/m². When conversion of low molecular weight newly-synthesized DNA to high molecular weight DNA was studied in both cell types, caffeine at 1.5 mM had no effect on this conversion in unirradiated cultures. At 5 J/m², caffeine had a transitory inhibitory effect on this conversion. However, at 10 J/m² caffeine had a strong permanent inhibitory effect on this conversion at doses higher than 0.5 mM in PDV cells and higher than 0.25 mM in EPD cells. This apparent inhibition of elongation by caffeine in irradiated cells could not be accounted for by an effect on the rate of DNA synthesis. In PDV cells there was a direct correlation in terms of effective caffeine dose level between synergistic reduction in cell survival after UV and the effect on DNA elongation. Irradiated EPD cells were more sensitive to the inhibitory effect of caffeine on DNA elongation.     

Establishment and characterization of a cell line (SS78) from a human renal cell carcinoma

Summary A new cell line, SS78, was established from a primary renal cell carcinoma of a Caucasian male. The tissue was dispersed with collagenase, and viable cells were separated by flotation on a Ficoll-Hypaque gradient. In culture, the SS78 cells retained a distinct epithelial morphology, and no fibroblastlike cells were seen. The cultured cells were aneuploid with a modal chromosome number of 80 and had several marker chromosomes. Inoculation of the cultured cells into athymic nude mice caused tumors at the sites of inoculation. This research was supported in part by Grants CA 15972 and CA 14930 from the National Cancer Institute through the National Bladder Cancer Project and by the Medical Research Service of the Veterans Administration.     

Ultrastructure of the lateral-line sense organs of the ratfish,Chimaera monstrosa

Summary The ultrastructure of the lateral-line neuromasts in the ratfish, Chimaera monstrosa is described. The neuromasts rest at the bottom of open grooves and consist of sensory, supporting, basal and mantle cells. Each sensory cell is equipped with sensory hairs consisting of a single kinocilium and several stereocilia. There are several types of sensory hair arrangement, and cells with a particular arrangement form patches within the neuromast. There are two types of afferent synapse. The most common afferent synapse has a presynaptic body and is typically associated with an extensive system of anastomosing tubules on the presynaptic side. When the tubules are absent, vesicles surround the presynaptic body. These synapses are often associated into synaptic fields, containing up to 35 synaptic sites. The second type of afferent synapse does not have a presynaptic body and is not associated with the tubular system. The afferent synapses of the second type do not form synaptic fields and are uncommon. The efferent synapses are either associated with a postsynaptic sac or more commonly with a strongly osmiophilic postsynaptic membrane. The accessory cells are similar to those in the acoustico-lateralis organs of other aquatic vertebrates. A possibility of movement of the presynaptic bodies and of involvement of the tubular system in the turnover of the transmitter is discussed. A comparison of the hair tuft types in the neuromasts of Ch. monstrosa with those in the labyrinth of the goldfish and of the frog is attempted.     

不同来源的肾综合征出血热病毒对Vero细胞的致病变作用

前文报道,肾综合征出血热病毒76-118株能使Vero细胞产生病变。本文报道76-118株和另11株不同来源的肾综合征出血热病毒(H537、A9、H5、R178、HB55、R22、Z10,沟3、L99、A16和J10)对Vero细胞的致病变作用(CPE )。其中除沟3株外,大部分毒株在感染Vero细胞后的第一代即可见明显的CPE。CPE的特点与76-118株相似,主要是感染细胞粘聚、融合,形成网状结构。CPE能被特异性抗HFRS病毒血清和型特异性单克隆抗体所中和抑制,但不能被特异性抗呼肠孤病毒Ⅲ型免疫血清所中和抑制。HFRS病毒对Vero细胞的致病变作用,对进一步研究HFRS病毒的某些生物学特性及实验方法等均有重要意义。     

视黄酸和亚硒酸钠对肝癌细胞某些表型逆转的加和作用

 人肝癌细胞株SMMC-7721经1μmol/L视黄酸和或2.5μmol/L亚硒酸钠处理后,膜上纤维连接蛋白沉着量逐日上升,且较相应天数的对照组细胞增加,而甲胎蛋白分泌量和~3H-TdR参入率被明显抑制。视黄酸和亚硒酸钠同时处理的联合组作用强度接近于两者单独使用时作用强度的加和。对以上结果和视黄酸及亚硒酸钠使肝癌细胞接触抑制恢复及表型逆转的关系作了讨论。     

Responsiveness of a human parotid epithelial cell line (HSY) to autonomic stimulation: Muscarinic control of K+ transport

Summary Salivary electrolyte secretion is under the control of the autonomic nervous system. In this paper we report that HSY, an epithelial cell line derived from the acinar-intercalated duct region of the human parotid gland, responds to muscarinic-cholinergic (generation of Ca²⁺ signal) andβ-adrenergic (generation of cAMP signal), but not toα-adrenergic (lack of Ca²⁺ signal), receptor stimulation. The muscarinic response was studied in detail. Carbachol (10⁻⁴ M, muscarinic agonist) or A23187 (5 μM, calcium ionophore) stimulation of HSY cells increases both⁸⁶Rb (K⁺) influx and efflux, resulting in no change in net equilibrium⁸⁶Rb content. Atropine (10⁻⁵ M, muscarinic antagonist) blocks both the carbachol-generated Ca²⁺ signal and carbachol-stimulated⁸⁶Rb fluxes, but has no effect on either the A23187-generated Ca²⁺ signal or A23187-stimulated⁸⁶Rb fluxes. Carbachol- and A23187-stimulated⁸⁶Rb fluxes are substantially inhibited by two K⁺ channel blockers, quinine (0.3 mM) and scorpion venom containing charybdotoxin (33 μg/ml). The inhibition of these stimulated fluxes by another K⁺ channel blocker, tetraethylammonium chloride (5 mM), is less pronounced. Protein kinase C (PKC) seems to be involved in the regulation of the⁸⁶Rb fluxes as 10⁻⁷ M PMA (phorbol ester, phorbol-12-myristate-13-acetate) substantially inhibits the muscarinic-stimulated⁸⁶Rb efflux and influx. Because this concentration of PMA totally inhibits the carbachol-generated Ca²⁺ signal and only 80% of the muscarinic-stimulated⁸⁶Rb influx, it seems that a portion of the carbachol-stimulated⁸⁶Rb flux (i.e. that portion not inhibited by PMA) might occur independently of the Ca²⁺ signal. PMA fails to inhibit the A23187-stimulated⁸⁶Rb fluxes, however, suggesting that PKC regulates Ca²⁺-sensitive K⁺ channel activity by regulating the Ca²⁺ signal, and not steps distal to this event. 4-α-Phorbol-12,13-didecanoate, a phorbol ester which fails to activate PKC, fails to inhibit either the carbachol-stimulated increase in intracellular free Ca²⁺, or carbachol-stimulated⁸⁶Rb fluxes.     

Immuno-Localization of DEAD Family Proteins in Germ Line Cells of Xenopus Embryos.

In order to investigate whether a vasa -like protein is present in germ line cells of Xenopus , antibodies were produced which react specifically with synthetic oligopeptides of sequences from near the N- or C-termini or with one including the DEAD box of the Drosophila vasa protein.
Only the antibody against the oligopeptide including the DEAD box reacted strongly with germ plasm (GP) or with cytoplasm of germ line cells of Xenopus embryos by immunofluorescence microscopy. By immunoelectron microscopy, the antibody was demonstrated to react with the GP-specific structure, germinal granules, in cleaving embryos, and with their derivatives in the germ line cells of embryos at stages extending from gastrula to feeding tadpole. It also reacted with mitochondria not only in the GP and the germ line cells but also in somatic cells, and with myofibrils in muscle cells. By Western blotting, the antibody was shown to react with several bands of Mr 42–69 ± 10³ in protein samples from Xenopus embryos. In samples from Drosophila ovaries, it reacted with a Mr 71 ± 10³ band which was probably the vasa protein. This indicates the possibility that Xenopus embryos contain several DEAD family proteins. One of these is present on germinal granules, resembling the vasa protein on polar granules of Drosophila .     

A Brassica campestris-alboglabra addition line and its use for gene mapping,intergenomic gene transfer and generation of trisomics

Summary Brassica campestris-alboglabra monosomic addition lines were developed from a trigenomic Brassica hybrid (2 n=3 x=29, AAC) obtained by backcrossing a resynthesized B. napus (2 n=4 x=38, AACC) line to its parental B. campestris (2 n=2 x=20, AA) line. One addition line was characterized genetically with three loci specific for the alien chromosome and cytologically by meiotic analysis. The following results were obtained. (1) The same chromosome in the B. alboglabra (2 n= 2 x=18, CC) genome carried the three loci, E _c, W _c and Lap-1 C ^c, which control the biosynthesis of erucic acid, white flower colour and the faster migrating band of leucine aminopeptidase, respectively. The linear order and possible positions of the three loci were inferred. The meiotic behaviour of the alien chromosome was documented and its transmission frequency was assessed. (2) Intergenomic recombination frequently occurred in the monosomic addition line, resulting in the introgression of one or two loci from the alien chromosome into the B. campestris genome. (3) B. campestris trisomics were found in the progeny of the monosomic addition line. (4) The removal of the other eight C-genome chromosomes from the trigenomic Brassica hybrid led to a dramatic increase in the erucic acid content of the monosomic addition line. (5) No offspring of the trigenomic Brassica hybrid showed evidence of intergenomic recombination and introgression of the W _c locus into the B. campestris genome. It is questioned whether such a difference might be due to a possible regulating mechanism for homoeologous chromosome pairing.