Growth of a human yolk sac tumor cell line with yolk sac-derived functions in selenium-supplemented chemically defined synthetic medium

Summary A human yolk sac tumor cell line, TG1, which was established from a testicular yolk sac tumor, was found to replicate continuously in a chemically defined medium supplemented with Na₂SeO₃ (ISRPMI). TG1 produced several plasma proteins and growth factors: albumin, alpha-fetoprotein (AFP), ferritin, carcinoembryonic antigen, beta-2-microglobulin, polyamine, neuron specific enolase, tissue polypeptide antigen, transferrin (Tf), epidermal growth factor, and platelet derived growth factor. By analysis of lectin (LcHA)-affinity electrophoresis, to examine the microheterogeneity of carbohydrate chains of synthetic glycoproteins, TG1 cells cultured with ISRPMI produced only LcHA reactive Tf and AFP based on core fucose attached to asparagine-linkedN-acetylglucosamine residues instead of LcHA-nonreactive Tf and AFP produced by TG1 cells cultured with fetal bovine serum (FBS)-containing medium.α1-6 Fucosyltransferase activity was significantly greater in the TG1 cells cultured with ISRPMI (39.9±1.5 pmol · h⁻¹ · mg⁻¹ protein) than cultured with FBS-containing media (18.2±1.2 pmol · h⁻¹ · mg⁻¹ protein). These results have indicated that the selective increase ofα1-6 fucosyltransferase occurred when the cells were cultured with the FBS-free synthetic media.     

Impact of whitefish on an enclosure ecosystem in a shallow eutrophic lake: changes in nutrient concentrations,phytoplankton and zoobenthos

Large bag-type (75 m³) and tube-type (105 m³) enclosures were set up in the shallow eutrophic Lake Suwa and were each stocked with exotic planktivorous whitefish (Coregonus lavaretus maraena). The release of whitefish caused the increase in nutrient concentration in the tube-type enclosure whereas no such increase was observed in the bag-type enclosure. Bottom sediment seemed to be an important source of chironomid food for whitefish. The proportion of phytoplankton measuring<10μm and 20–40μm, which respectively corresponded toOchromonas spp. andCryptomonas sp., were lower in the fish enclosures than in the control, which might have been caused by high grazing pressure by rotifers. The predation by whitefish might have affected the species composition of phytoplankton through reducing copepod predation on rotifers, not through reducing the densities of cladocerans which directly feed on phytoplankton as many investigators have reported. The phytoplankton biomass was not affected much by the release of fish. Possible reasons are that the increase in density of rotifers reduced the biomass of available phytoplankton and also that inedible Cyanophyceae were in the decreasing phase of their seasonal succession and could not increase successfully in spite of elevated nutrient levels.     

There are two major types of hepatitis C virus in Japan

The polymerase chain reaction (PCR) was used to detect hepatitis C virus (HCV) in plasma from chronic non-A, non-B hepatitis patients. By choice of adequate primers, 19 of 24 samples (79%) were found positive. Sequence analysis of amplified 400 bp cDNA fragments encoding a portion of NS5 gene suggested that HCV can be classified into two types (named K1 and K2) in Japan. Slot blot hybridization of the fragments indicated that 13 were HCV-K1 and 6 were HCV-K2, which show 80% and 67% nucleotide sequence homology, respectively, with that of the prototype.     

Cysteine proteinase inhibitor in the ascitic fluid of sarcoma 180 tumor-bearing mice is a low molecular weight kininogen. Partial NH2- and COOH-terminal sequences and susceptibility to various glandular kallikreins

It has been proposed that a cysteine proteinase inhibitor (CPI) found in the ascitic fluid of Sarcoma 180 tumor-bearing mice is a kind of kininogen (Itoh, N., Yokota, S., Takagishi, U., Hatta, A., and Okamaoto, H. (1987) Cancer Res. 47, 5560-5565). The first 40 NH2-terminal residues and 54 residues of the COOH-terminal sequence, including the bradykinin moiety of highly purified ascites CPI, were determined and compared with those of mammalian low molecular weight kininogens (LMWK). The significant identity between these amino acid sequences with those of other mammalian LMWKs suggests that ascites CPI corresponds precisely to mouse LMWK. This kininogen has a light chain composed of 43 amino acid residues, which contains a unique Met-Ala-Arg-bradykinin sequence. Hydroxyproline, which was recently identified in the bradykinin sequence of kininogen from the ascitic fluid of a cancer patient, was not found in the kinin moiety of this mouse kininogen. Among purified glandular kallikreins from human, hog, rat, and mouse, only mouse submaxillary gland kallikrein was able to release bradykinin from this kininogen. Kinetic studies using a newly synthesized fluorogenic substrate, N-t-butoxycarbonyl-Met-Ala-Arg-MCA, revealed that mouse kallikrein hydrolyzes this substrate approximately 80-fold faster than does hog kallikrein, suggesting that the unique Met-Ala-Arg-bradykinin sequence is responsible for the varied susceptibility of mouse kininogen to different kallikreins.     

Selective adhesion of embryonal carcinoma cells and differentiated cells by Ca2+-dependent sites

The specificity of adhesion between embryonal carcinoma cells and fibroblastic cells of various origins was studied. Embryonal carcinoma cells have intercellular adhesion sites requiring Ca²⁺ (CDS). These sites were found to be sensitive to proteases but resistant to them in the presence of Ca²⁺. CDS with a similar protease sensitivity is present in fibroblastic cells. When embryonal carcinoma cells of different lines were mixed, they adhered to each other nonselectively by CDS. Nonselective adhesion by CDS occurred also between fibroblastic cells of various lines. When embryonal carcinoma and fibroblastic cells were mixed, they preferentially adhered to homotypic cells. Fab fragments of antibodies raised against F9 cells (a nullipotent line of embryonal carcinoma) inhibited the adhesion between embryonal carcinoma cells but not between fibroblastic cells. This inhibitory activity of Fab was absorbed with embryonal carcinoma cells with CDS, but not with fibroblastic cells with CDS or embryonal carcinoma cells from which CDS was experimentally removed. SDS-polyacrylamide gel electrophoresis of radioiodinated cell surface proteins showed that the presence of a 140K-dalton component correlated with the presence of CDS in embryonal carcinoma cells, while the presence of a 150K-dalton component correlated with the presence of CDS in fibroblastic cells. These results suggest that CDS in embryonal carcinoma and fibroblastic cells comprise distinct molecules.     

An anchorage-dependent locus in the cell cycle for the growth of 3T3 cells

Mouse fibroblasts, 3T3 cells, require a solid surface for continuous growth, but when 3T3 cells, during their exponential phase in Petri dishes, were transferred to a suspension culture, the number of cells roughly doubled by 30 h. During the suspension culture the number of pairing cells (c₂) increased, but that of the single cells decreased. When cells synchronized at mitosis or at the G1-S boundary were transferred to the suspension culture, the number of pairing cells peaked at 30 min and at 10 h, respectively. DNA synthesis began immediately after the cells, which were cultured for 16 h in the suspension, had settled onto the surface of the Petri dishes. When cells in a confluent culture were arrested at an early G1 period and were suspended, the number of pairing cells did not increase. These results indicate that the most important locus for anchorage growth seems to be at a late G1 period of the cell cycle.     

Studies on rat liver argininosuccinate synthetase. Inhibition by various amino acids.

Inhibition studies of crystallized rat liver argininosuccinate synthetase [EC 6.3.4.5] are described. 1. L-Argininosuccinate, L-histidine, and L-tryptophan inhibited the enzyme activity at saturating amounts of the substrates. 2. L-Norvaline, L-argininosuccinate, L-arginine, L-isoleucine, and L-valine competitively inhibited the enzyme activity at a low concentration of L-citrulline, with Ki values of 1.3 x 10(4) M, 2.5 X 10(-4) M, 6.7 X 10(-4) M, 6.3 X 10(-4) M, and 6.0 x 10(-4) M, respectively. 3. L-Argininosuccinate and L-arginine competitively inhibited the enzyme activity at a low concentration of L-aspartate, with Ki values of 9.5 x 10(-4) M and 1.2 x 10(-3) M, respectively. 4. The modes of inhibition by L-histidine were mixed-noncompetitive, uncompetitive, and noncompetitive types with respect to L-citrulline, L-aspartate, and ATP, respectively. 5. When the enzyme was preincubated with L-citrulline, the enzyme activity was slightly increased in the presence of a low concentration of L-histidine in the assay mixture. 6. The conformation of the enzyme was markedly changed by the addition of L-histidine as judged from the CD spectrum. This change was partially reversed by incubation with L-citrulline.     

Oxidative Degradation of Squalene by Arthrobacter Species

An organism isolated from soil and identified as Arthrobacter sp. was studied for its squalene degradation. The degradation product from squalene, which accumulated in the culture broth, was isolated and identified as trans-geranylacetone by mass spectrometry, gas chromatography, infrared spectrometry, and nuclear magnetic resonance spectrometry. Addition of a high concentration of K₂HPO₄ to the culture medium resulted in accumulation of fairly large amounts of carboxylic acids in addition to geranylacetone. These carboxylic acids were identified as isovaleric, β,β′-dimethylacrylic, geranic, and (+)-(R)-citronellic acids. Among these acids, α,β-saturated carboxylic acids were found to be predominant in quantity.     

Genes affecting the productivity of alpha-amylase in Bacillus subtilis Marburg.

Genetic control of alpha-amylase (alpha-1,4-glucan glucanohydrolase, EC 3.2.1.1.) production by Bacillus subtilis 168 was studied from the standpoint that alpha-amylase production by bacteria is dependent on a long-lived messenger ribonucleic acid and obeys the following equation: E = kappa integral of X-DT where x = cell mass at time t, E = alpha amylase produced, t = culture time, and kappa = productivity constant. So a productivity constand (kappa) is obtained from the slope of the straight line plot of alpha-amylase formed versus the total mass of cells accumulated over that time during the culture process. The following results were obtained. (i) Two sequential mutants, derived from the 168(kappa = 20) strain and having improved alpha-amylase productivity (168 leads to 196), were analyzed for their serine and metal protease production. Strain 128 (kappa = 40) produced half the amount of both proteases, but strain 196 (kappa = 60 similar to 80) produced 20 times that in the original strain. (ii) Amy+ transformants, using the 196 strain as the other three had higher productivity (kappa = 37 similar to 46). These transformants (J71, J47, groups. Seventy-one of 74 Amy+ transformants had a kappa value of 21.0 plus or minus 2.1 and the other three had higher productivity (kappa = 37 similar to 46). These transformants (J71,J47, and J10) produced levels of serine and metal proteases 20 times higher than the other transformants. (iii) Strains 196, J71, J47, and J10 were found to be nonmotile and resistant to phage PBS1, whereas other strains, including strains 168, 128, 3 revertants of strain J71 and 2 revertants of strain 196, were all motile and sensitive to the phage. (iv) Strains 196 and J71 were nonflagellated under electron microscopic observation but strain 168, 128 and a revertant of J71 were flagellated. From the above experimental results, the existence of a quality controlling gene (amyB) was deduced, which is loosely linked to the structural gene and controls productivities of alpha-amylase and proteases, and flagellation. The probable existence of another regulatory gene, amyC, is also discussed.