条件培养液中的活性组分

条件培养液中含有细胞分泌的活性物质,因此,条件培养液可再现体外培养细胞或组织的微环境,促进或抑制来源不同的细胞或组织的生长、增殖和分化,也被用于研究各种生理或病理现象的机制。当前,国内外研究较多的有乳腺癌细胞系MDA-MB-231细胞、骨髓内皮细胞、坐骨神经和肝细胞等的条件培养液。     

The Venetian Turpentine Mounting Medium

As a mounting medium to follow aceto-carmine the following modification of Zirkle's is suggested: Venetian turpentine, 25 ml.; phenol, 50 ml.; propionic acid, 35 ml.; acetic acid, 10 ml.; water, 20 ml. The technic can be employed with either root-tip or pollen-mother smears, and has been used with quite a variety of plants. It is especially valuable where it is desired to make temporary mounts permanent. The method is simple, and with reasonable care no displacement of marked cells occurs.     

The Effect of Medium Composition upon the Production of Pyocin

Cetrimide (0.03% w/v), added to a semi-synthetic medium, raised pyocin titre tenfold over the other media tested, maintained the high level of pyocin for up to 24 h and also reduced slime production by Pseudomonas aeruginosa , thus facilitating extraction and purification of pyocin.     

The Nature of the Reaction of the Colon Organism on Endo's Medium

Bacterium coli was grown in a medium of a composition similar to Endo's medium with the exception that the sulfite, fuchsin and agar were left out. When the fuchsin-sulfite mixture was added after 24, 36 and 48 hours, or after 3 and 10 days of incubation at 37°C., no reaction appeared. The substance that causes the reaction is only formed when the bacteria are grown in the presence of sulfite. When picric acid and ether are added to the red compound produced by the colon organism in Endo's medium and the mixture shaken, the color remains in the watery layer and thus the dye color that appears in the medium is not restored fuchsin, but a new substance. The work confirms Neuberg's and Nord's theory that the Endo medium acts as a trapping agent for the intermediate product, acetaldehyde, which causes the Endo reaction.     

玫瑰色微球菌的生物学特性及其培养基的优化

对本实验室分离纯化的玫瑰色微球菌（Micrococcus roseus）M1进行生物学特性研究,包括形态与培养特征的观察,细胞色素的测定,菌体对碳氮源和生长因子的利用,以及该菌株的最适生长条件。通过单因素试验,获得菌株最适生长条件为：培养温度30℃、p H7.5、振荡频率120 r/min、盐度0.5%。采用均匀设计法优化菌株M1的培养基,得到最优培养基（g.L-1）：CH3COONa 6;NH4Cl 2.4;Na HCO30.1;Mg SO40.1;维生素溶液12 m L/L;微量元素溶液1 m L/L。在最适生长条件下,接种菌株M1于最优培养基,培养72 h后,菌体和类胡萝卜素的OD值分别达到2.753和4.733,而在基础培养基上的生物量和类胡萝卜素的OD值为1.895和3.258,分别提高了45%和50%。     

The Detection of Clostridium welchii in the Differential Reinforced Clostridial Medium Technique

S ummary . The enumeration of sparse populations of clostridia by a total clostridia count technique in a fluid medium (DRCM) gives small estimates of the numbers of Clostridium welchii. This organism may be readily detected in mixed 'presumptive total' clostridia cultures by streaking on lactose-egg yolk-milk agar before pasteurizing these cultures. The results of screening poultry carcases and processing plants with this technique are presented and the incidence of Cl. welchii on 3 sites of poultry carcases (breast, vent and neck skin) are compared for 3 processing plants.     

The Reaction of the Medium in Relation to Root Formation in Coleus

Background: As seed dispersal can vary among years and individuals, studies that focus on a single year or on a few individuals may lead to erroneous conclusions.

Aims: To study temporal and spatial intraspecific variation of seed dispersal in Scrophularia canina, a widespread species with capsule-type fruit.

Methods: Primary seed dispersal was quantified by placing traps in each cardinal direction around 10 individuals during two consecutive years. We correlated several seed shadow parameters (modal dispersal distance, kurtosis, skewness, percentiles, slope, and seed percentage beneath the plant canopy) with three plant features (maximum height, lateral spread and seed production).

Results: Scrophularia canina dispersed their seeds by boleochory, giving rise to a typical leptokurtic curve, but behaving as a barochorous species, because about 90% of seeds landed beneath the plant canopy. Temporal dispersal in S. canina included several seed waves associated with maximum wind speeds. Plant lateral spread was significantly positively correlated with seed percentiles and percentage of seeds beneath the plant canopy regardless of year. A seed production effect was only evident when both years were considered together.

Conclusions: Although time-consuming, investigation of the dispersal process for more than 1 year provides more realistic information on seed dispersal. Lateral spread is the main plant feature determining seed shadow.     

Compressing Proteomes: The Relevance of Medium Range Correlations

We study the nonrandomness of proteome sequences by analysing the correlations that arise between amino acids at a short and medium range, more specifically, between amino acids located 10 or 100 residues apart; respectively. We show that statistical models that consider these two types of correlation are more likely to seize the information contained in protein sequences and thus achieve good compression rates. Finally, we propose that the cause for this redundancy is related to the evolutionary origin of proteomes and protein sequences.     

The Cultivation of Symbiote-free Marine Ciliates in Axenic Medium

SYNOPSIS. Media have been developed for axenic cultivation of 10 strains belonging to 7 species of small marine ciliates. A medium containing cerophyl extract, proteose peptone, trypticase, yeast nucleic acid, biotin, calcium pantothenate folic acid, nicotinamide, pyridoxal HCl, riboflavin, thiamine HCl, and DL-thioctic acid in sea water supports the growth of Uronema nigricans strains Pc and 34/2, Parauronema virginiatum strains 2/1 and 19/1, Miamiensis avidus strains Ma and 19/3, Miamiensis sp. strain 1/1, a strain of "G" ciliate, and strains 33/8 and 34/7 of 2 unidentified species. By substituting a mixture of asolecithin, cephalin, and Tween 80 for cerophyl in the medium, luxurious growth of all except the strains of the 2 unidentified species can be obtained. A defined medium consisting of 18 amino acids, 5 purine derivatives, 8 vitamins, asolecithin, cephalin, and Tween 80 in synthetic sea water also has been developed for 6 of the strains: M. avidus Ma and 19/3, Miamiensis sp. 1/1, P. virginiatum 2/1 and 19/1, and U. nigricans Pc. In general the ciliates grow best at pH 7.2 in the dark at 27 C in media containing sea water of density = 1.015. Under these conditions maximum populations are reached in 4–5 days and range from several hundred thousand to 3 or 4 × 10⁶ depending upon the strain. Electronmicroscopic observations for the presence of endosymbiotes gave negative results.     

Gentamicin-Based Medium for the Isolation of Group D Streptococci and Application of the Medium to Water Analysis

Gentamicin-thallous-carbonate (GTC) medium contained (per liter): 40.0 g of Trypticase soy agar, 5.0 g of KH₂PO₄, 2.0 g of NaHCO₂, 1.0 g of glucose, 1.0 g of esculin, 0.5 g of thallous acetate (TA), 0.5 g of ferric citrate, 0.75 ml of Tween 80, and 2.5 mg of gentamicin sulfate. The NaHCO₃ (20 ml of a 10% solution that had been heated to boiling) was added after sterilization of the basal medium. The spread plate technique was used to compare GTC agar with Pfizer selective enterococcus, TA, and KF agars by using sewage as well as bovine and swine fecal samples. Significantly greater numbers of group D streptococci were recovered on GTC agar than on Pfizer selective enterococcus or KF agars, within and over all samples. Higher counts also were obtained on GTC than on TA agar, but the differences were not statistically significant. The percentage of false positives was about the same for all four media. Samples of riverwater also were plated on GTC, TA, and KF agars, and significantly higher recoveries were obtained with GTC agar. GTC agar was superior to the other media examined primarily because of increased recoveries of Streptococcus bovis and S. equinus; other advantages of GTC agar were large colony size and short (24-h) incubation period. The percentage of false positives from riverwater was 13% for GTC agar and 0% for TA and KF agars; therefore, confirmation would be necessary when GTC agar is used with some types of environmental samples.     

活性碳对培养基中植物生长调节物质的吸附作用

植物组织和细胞培养中经常使用活性碳(Johansson等1982,Fridborg和Eriksson 1975,Smith 1983,Steinitz和 Yahel 1982)。一般认为活性碳通过吸附而发生作用(Fridborg和Erik-sson 1975,Kohlenbach 和 Wernicke 1978,Martineau等1981)。但关于活性碳吸附何种