Studies on the variations in generation times of rat hepatoma cells in culture

The proliferation kinetics of a cultured hepatoma cell line, HTC, was studied by time-lapse photography and autoradiography. Variability of G1 phase, S phase and intermitotic times of sister cells were compared with data on the variability of G1 phase, G2 phase, S phase and intermitotic times of unrelated cells. Evidence is presented that the variation in times spent in intermitosis by a pair of sisters is determined by the variation of G2 phase durations, while the variation in intermitotic times of unrelated cells is mainly determined by the variation of G1 phase times.     

Identification of experimentally induced colitis by in vitro nuclear magnetic resonance

The present study determined whether in vitro nuclear magnetic resonance could be used to assess experimentally induced colitis in rats. Acute colitis was induced in 6 Sprague-Dawley rats by acetic acid enema, while 6 control animals received saline enemas. All animals were sacrificed 24 hours post-enema, and NMR relaxation times, T1 and T2, of colonic samples were determined on a 10 MHz spin analyzer (RADX, Houston, TX). Colonic water content was determined on the same samples by desiccation. Colitis animals showed significantly higher T1 and T2 relaxation times and tissue water content than controls. T1 and T2 times correlated significantly with tissue water content. Twelve additional animals were studied histologically, six of which received acetic acid enemas and showed extensive transmural colitis. Our results suggest that in vivo proton NMR might be a useful means of non-invasively assessing the degree of colonic inflammation.     

正交设计优选超声辅助提取柑桔叶精油工艺研究

采用溶剂萃取法提取柑桔叶中的精油,并优化工艺条件。通过气相色谱、质谱等仪器对所提取的精油组分进行鉴定分析。最终得到最佳提取条件:用6倍石油醚浸泡4 h,超声60次,可得到较好产率,产率1.73%。利用气相色谱-质谱联用法对柑橘叶精油的化学组成进行分析,用归一化法测定其相对百分含量,共分离出387种成分,鉴定了其中的32种成分,占出峰物质总量的70.22%,主要成分为β-氧化石竹烯(10.15%)、十六烷酸(8.15%)、芳樟醇(6.31%)、α-甜橙醛(4.33%)、亚油酸(6.48%)、视黄醛(4.04%)等成分。     

The effects of temperature and food on naupliar development,growth and metamorphosis in three species of Boeckella (Copepoda:Calanoida)

Three species of Boeckella (B. triarticulata, B. dilatata and B. hamata) were reared from hatching to copepodite I (CI) at three naturally fluctuating food levels and three temperatures in a 3 × 3 × 3 factorial design. Development times, lengths and mortality were measured for each species in nine treatments. Temperature had the major effect on development times but food level had the major effect on CI lengths. Mortality varied interspecifically with treatment. The combined effect of temperature and food on development times and lengths was species-specific. There were trade-offs between development time and growth to meet constraints imposed by naupliar metamorphosis. The three species varied in the timing of metamorphosis to CI. B. triarticulata nauplii were age determined, B. dilatata nauplii were size determined and B. hamata nauplii were flexibly age and size determined depending on treatment. Differences in life history parameters and the timing of naupliar metamorphosis are discussed in relation to the distributions of the species in ponds (B. triarticulata), glacial lakes (B. dilatata) and coastal lakes (B. hamata) in the South Island of New Zealand.     

Ploidy variation of progenies from intra- and inter-ploidy crosses with regard to trisomic production in asparagus (<Emphasis Type="Italic">Asparagus officinalis</Emphasis> L.)

Ploidy variation within progenies from intra- and inter-ploidy crosses of asparagus were determined in this study. The DNA content of most reduced microspores was half that of somatic cells in diploid, triploid and tetraploid plants as determined by flow cytometry. Many viable seeds were obtained from various 2x × 2x and 2x × 3x intra- and inter-ploidy crosses. Nuclear DNA contents of these progenies from reciprocal crosses between diploids and triploids were similar to those expected of diploids, but with a wider range: hyper- and hypo-diploids including trisomics seem to be involved in the progenies. Indeed, the number of chromosomes in the progenies of 2x × 3x crosses ranged from 18 to 23. Based on frequencies of viable seeds and trisomic phenotypic appearance, it was concluded that the 2x × 3x cross was most efficient for obtaining trisomic plants in Asparagus officinalis.     

Gas Chromatographic Presumptive Test for Coliform Bacteria in Water

A gas chromatographic procedure which shows promise as a presumptive test for coliform bacteria in water is described. Total coliform bacteria concentrations were determined from the incubation times at 37 C required for ethanol to be produced. Fecal coliform densities were determined in a similar manner at 44.5 C. The culture medium was filter sterilized M-9 salts supplemented with 1% lactose, 0.1% Casamino Acids, and 0.1% yeast extract. Best results were obtained when the initial total coliform concentrations were 5 per ml or higher and when fecal coliform concentrations were 50 per ml or higher. Minimum detection times at these concentrations were 9 and 12 h, respectively.     

天津地区家蝇抗药性水平及与两种解毒酶的关系

用点滴法对采自天津市7个郊区县的7个不同生境野外家蝇种群的抗药性进行了测定并与实验室内的相对敏感种群进行比较;对不同地区家蝇种群进行了羧酸酯酶（carboxylesterase, CarE）和谷胱甘肽S-转移酶（glutathione S-transferase, GSTs）活性检测。结果表明,不同家蝇种群对DDVP、高效氯氰菊酯和残杀威的抗性倍数不同,对DDVP抗性最高为18.563倍,最低为1.885倍;对高效氯氰菊酯最高为14.071倍,最低为1.071倍;对残杀威抗性倍数最高为7.499倍,最低为1.071倍。从CarE平均比活力看,室外家蝇种群CarE的比活力均高于室内相对敏感种群的比活力,CarE活性的分布在敏感种群和不同地区野外种群间具有明显的重叠现象。天津不同地区F₂代家蝇GSTs的比活力抗性种群普遍高于室内相对敏感种群,大约在2～4倍之间,不同地区间也具有比较大的差异,而抗药性高的种群GSTs活性也高,GSTs活性变化与不同种群抗性差异是相符的。     

Cloned complementary deoxyribonucleic acid of Drosophila cells. Relationship of genome copy number to messenger ribonucleic acid abundance

Recombinant DNA plasmids containing DNA sequence complementary to poly(adenylic acid) [(poly(A)] containing RNA from the cytoplasm of Drosophila Kc tissue culture cells were constructed. The reiteration frequency in the genome of the RNA homologous to the 20 randomly selected clones was determined by two rapid methods. Of the 20, 17 were determined to be single copy, 2 were repeated several (2-4) times, and 1 was repeated approximately 10 times. The steady-state level of mRNAs homologous to the 20 cDNAs was quantitated and varied more than 160-fold. The RNAs ranged from 0.16% to less than 0.001% of the poly(A)-containing RNA.     

Distribution of turbidity detection times produced by single cell-generated bacterial populations

The distributions of the times to turbidity for wells inoculated with single cells of Listeria innocua were determined in different environmental conditions (pH 4.5 to 7 and with 0.5% to 8% of NaCl at 30 degrees C). It was established by statistical analysis that the main source of the variability of the detection times, T, is the variability of individual lag times. A linear relation dev(T) approximately T was observed between the detection times and their standard deviation. At slow growth, other sources of variability became increasingly significant.     

Nuclear magnetic relaxation studies of cytidine and its complexing dimethyl sulfoxide solution.

13C spin-lattice relazation times (T1 values) in cytidine were determined experimentally to investigate molecular motions of both metal-free and ion-complexed cytidines in dimethylsulfoxide solutions. It was found that the correlation times of the protonated carbons were equal within experimental error, and this equality of correlation times of different sites of the molecule suggests strongly isotropic random motion of the molecule. Correlation times for internal motion of the amino group obtained from the observed T1 of the amino protons are 4.6 -10(-11) S, 2.0 - 10(-9) S and 1.1 - 10(-10) S for the metal-free cytidine and the cytidine complexed with either CaCl2 or ZnCl2, respectively. An experimental value of T1 of the H6 proton of the cytidine base agrees very well with the value estimated from a conformation determined by the nuclear "Overhauser" effect. Spin-lattice relaxation time measurements of the 7Li nucleus in the LiCl/cytidine system strongly suggested that the 7Li cation is directly coordinated with cytidine.     

Effect of Sodium Chloride Concentration in an Agar Medium on Growth of Heat-Shocked Staphylococcus aureus

The numbers of Staphylococcus aureus 196E surviving heat treatment in milk for various times at 60 C were determined by plate count with normal and modified Staphylococcus Medium No. 110 (S-110), with Plate Count Agar (PCA), and by milk enrichment techniques. Portions of specific heated samples appeared to contain lower populations of S. aureus 196E when the survivors were enumerated with normal S-110 than with PCA. Similarly, the times at 60 C needed for total destruction of the culture suspension in the test milk appeared to be shorter when survival was determined with normal S-110 agar. The apparently lower thermal death times were found to be related to the NaCl content of the S-110 medium, because use of S-110 agar containing lesser concentrations of NaCl resulted in growth of larger numbers of heat-shocked S. aureus 196E.     

Nuclear magnetic resonance study of squid giant axon

Using a spin-echo technique, the spin-lattice and spin-spin relaxation times (T1 and T2) of water protons in a single nerve fiber (giant axon of squid) were determined. Similar measurements were also carried out on axoplasm extruded from these nerve fibers. It was found that the relaxation times of water protons of both the intact fiber and the extruded axoplasm are approximately equal (and much less than those of a free solution), suggesting that the relaxation times of cellular water are shortened mainly by water-protein interactions rather than by water-membrane interactions.     

Physical state of phenanthrene for utilization by bacteria

Experiments were done to determine if bacteria able to utilize phenanthrene as a sole source of carbon obtain the hydrocarbon directly from solid phenanthrene particles suspended in the medium or from the phenanthrene dissolved in the medium. Growth experiments were done in gas-tight fermentors completely filled with air-saturated, mineral salts solution with phenanthrene as the substrate. Generation times were determined by rate of oxygen consumption. Generation times were independent of the amount of solid phenanthrene present, and these generation times were the same as the generation time on medium containing only dissolved phenanthrene. It was concluded that bacteria utilize phenanthrene in the dissolved state.     

NUCLEAR RIBONUCLEASE ACTIVITIES OF RAT BRAIN DURING POSTNATAL DEVELOPMENT

Abstract— The activities of alkaline and acidic RNAses were determined in soluble and insoluble fractions from nuclei of brain hemispheres of rats, aged from 1 day to adult. The activities increased rapidly and reached a maximum, at 30 days, of about 10 times (alkaline RNAsel or 5 times (acidic RNAse) that seen at day 1.     

Optimization of conditions for in situ hybridization and determination of the relative number of ribosomes in the cells of the mature embryo sac of maize

Summary We have initiated experiments to understand the molecular regulation of embryo sac development in flowering plants by a study of ribosome synthesis and accumulation. Because of the very small size of the embryo sac and the large volume of ovule tissue it is embedded in, in situ hybridization with nucleic acid probes is presently the only practical method for such molecular measurements on individual cells of the embryo sac. Methods of tissue preparation, sectioning and screening of ovules for embryo sac containing sections, in situ hybridization using a ribosomal mRNA probe, and staining were optimized. Relative densities of silver grains for individual cells of the mature maize (W22) embryo sac were determined from in situ hybridizations. The silver grain counts are directly related to the numbers of ribosomes. Volumes of individual cells were determined by confocal microscope image analysis, and this permitted the calculation of the relative total numbers of ribosomes in individual cells of the embryo sac and nucellus. The central cell has a volume 260 times that of a nucellar cell at the micropylar end of the ovule, 15 times that of the egg cell, 30 times that of a synergid, and 130 times the volume of an antipodal cell. The mature maize embryo sac has 20 or more antipodal cells. The central cell has approximately 200 times the number of ribosomes as are present in a nucellar cell, about 7 times as many ribosomes as are in the egg cell, 14 times as many ribosomes as in each synergid, and about 80 times the ribosome content of individual antipodal cells. The data are discussed with respect to the utilization of the ribosomes following fertilization in the early embryo and endosperm.     

Lifetimes of photosystem I and II proteins in the cyanobacterium Synechocystis sp. PCC 6803

The half-life times of photosystem I and II proteins were determined using (15)N-labeling and mass spectrometry. The half-life times (30-75h for photosystem I components and <1-11h for the large photosystem II proteins) were similar when proteins were isolated from monomeric vs. oligomeric complexes on Blue-Native gels, suggesting that the two forms of both photosystems can interchange on a timescale of <1h or that only one form of each photosystem exists in thylakoids in vivo. The half-life times of proteins associated with either photosystem generally were unaffected by the absence of Small Cab-like proteins.     

Toxicity of pesticides to the citrus leafminer and its parasitoid Ageniaspis citricola evaluated to assess their suitability for an IPM program in citrus nurseries

The relative toxicity of pesticides to Phyllocnistis citrella and its parasitoid Ageniaspis citricola was compared by several bioassay methods. A clip-cage bioassay measured survival of adults exposed to fresh residues at 0.25-times (0.25×), 0.5×, 1×, and 2× the lowest recommended rate of each pesticide, a water control (0×), and 24- and 48-h aged residues of oil at 1.5% (1×) rate. A one-species cylinder bioassay determined the effects of pesticides on immature stages of the citrus leafminer after treating young citrus trees with the same rates of pesticides (except for avermectin, tested at 0×, 0.01×, 0.025×, 0.05×, 0.1×, and 0.25× rates). A sublethal rate of petroleum oil (0.4%) was added as an adjuvant in some treatments. The effect of pesticides on immature stages of A. citricola was determined with a two-species cylinder bioassay after treating young citrus trees with the same rates as above. An index of IPM compatibility was developed based on the efficacy of the pesticide as a control agent of the leafminer (or other pests) and its selectivity to the parasitoid at the lowest recommended field rate (0.25× the field rate for avermectin). Azadirachtin (Neemix) + oil, diflubenzuron (Micromite) + oil, fenoxycarb (Eclipse) + oil, and oil alone (FC 435-66) were classified as IPM-compatible insecticides. Sprays of azadirachtin (Align) + oil, neem oil (Neemgard), and drenched imidacloprid (Admire) were ranked as a semi-compatible insecticides. The fungicide copper hydroxide (Kocide 101) and a fish oil-based foliar fertilizer (Zapata HFE) were considered compatible. Avermectin (Agri-Mek) + oil, ethion (Ethion), and imidacloprid (Provado) applied as a spray were IPM-incompatible insecticides. These products should be tested under field conditions to confirm these ratings.     

The effect of disinfectants on a geosmin-producing strain of Streptomyces griseus.

This study describes the bactericidal and sporicidal effects of four disinfectants on a geosmin-producing strain of Streptomyces griseus. The disinfectants investigated were chlorine, chloramine, chlorine dioxide and ozone. Chlorine and chlorine dioxide at concentrations around 1 mg/l were effective inactivators of both spore and mycelial propagules. Decimation times of less than 1 min were determined in each case. Both growth forms exhibited a high ozone demand, but decimation times resulting from an initial dose of around 2.5 mg/l were approximately 1.5 min. Monochloramine was comparatively less effective: at a concentration of approximately 1 mg/l the decimation times for spores and mycelia were 13.8 and 22.7 min, respectively.     

Dynamics in Polysaccharide Glasses and Their Impact on the Stability of Encapsulated Flavors

The aim of this work is to examine the correlation between measured instability of model flavor compounds in glassy matrices with the calorimetric relaxation times of the matrices. Spray-dried carbohydrate matrices were chosen as the model compounds for this study. Enthalpy relaxation times were determined for spray-dried carbohydrate matrices using differential and isothermal calorimetric methods. The losses of the volatile methyl acetate, ethyl acetate and limonene, as well as formation of limonene oxidation products, were measured by gas chromatography. Storage conditions were 30 and 40 °C, with samples equilibrated with 11, 23, 33 and 43 % RH at each temperature. A comparison of the relaxation times for temperatures below Tg was made using Modulated DSC (MDSC) and a Thermal Activity Monitor (TAM). TAM yields significantly lower values for relaxation times implying that it is capturing some of the faster dynamics as well as dynamics that are activated near Tg. However, plots of relaxation times as determined by both techniques versus temperature appear to converge at Tg. An increase in the relative humidity results in moderately higher loss of volatiles (methyl acetate, ethyl acetate and limonene) and greater oxidation rates. In general, there is a good correlation between relaxation time and stability, with greater enthalpy relaxation time associated with better stability. Enthalpy relaxation time appears to be a useful predictor of stability for both loss of volatiles and oxidation of limonene.     

银耳子实体多糖高温高压提取工艺研究

通过对银耳子实体多糖高温高压提取工艺中,提取温度、料液比、提取时间,提取次数等影响因素的实验分析,确定银耳子实体多糖高温高压提取的最佳条件为:提取温度110℃(对应压力0.04 MPa);料液比为1∶70;提取时间为2 h;提取次数为2次,在此条件下,银耳子实体多糖提取率可达36.5%。