Laboratory strains

Alternatively, fabric patches treated with permethrin have been evaluated against natural and laboratory strains of human body flee in Pern. Permethrin-treated fabric is toxic to flee on contact and quickly affects feeding behavior, even when washed up to 20 times. Thus permethrin-treated clothing intermpts disease transmission, and offers a passive louse control not previously feasible (39). 

Acquired resistance to bacitracin has been observed in laboratory strains of Staph, aureus, but resistance has been unstable and no resistant mutants have yet been isolated in vivo. Gram-negative bacteria are intrinsically resistant to bacitracin, which inhibits the transfer of pentapeptide units to petidoglycan. 

Lack of repeatability of the results of metabolic studies using laboratory strains that have been maintained by repeated transfer for long periods under nonselective conditions may be encountered. These strains may no longer retain their original metabolic capabilities, and this may be particularly prevalent when the strains carry catabolic plasmids that may have been lost under nonselective conditions. For these reasons, strains should be maintained in the presence of a cryoprotectant such as glycerol at low temperatures (-70°C or in liquid Nj) as soon as possible after isolation. Freeze-drying is also widely adopted, and is recommended. 

The presence of a PHA synthase alone is not sufficient to allow synthesis of PHAs. PHA biosynthesis will not occur if genes encoding enzymes required for the synthesis of hydroxyacyl-coenzyme A thioesters are absent or if the pathways constituted by these enzymes are for whatever reason not functionally active. This becomes evident, for example, when a PHA synthase gene is expressed in wild type or normal laboratory strains of E. coir, even if a functionally active PHA synthase is expressed, no or only traces of PHAs are accumulated. 

Human embryo lung fibroblasts infected with a reference laboratory strain of herpes simplex virus (HS V) type 2 were used to detect antibody to HSV type 2 in serum samples. After treatment of cells with serial dilutions of sera, HRP-labeled immunoglobulins to human IgG (class G immunoglobulins) were added and detected with CL substrate [36], In both cases a sharp detection of the specific antibodies was achieved with chemiluminescent assays, which proved more sensitive than the colorimetric immunoperoxidase assays. 

Many species of aquatic organisms are adversely affected at concentrations in water between 0.2 and 3.0 pg/L technical chlordane. Sensitive bird species had reduced survival on diets containing 1.5 mg chlordane per kilogram ration, or after a single oral dose as low as 14.1 mg chlordane per kilogram body weight. Chlordane has produced liver cancer in laboratory strains of domestic mice, but carcinogenicity has not been established in other mammals. 

Fig. 3 Lethal efficacy of Metofluthrin against field strains of Culex quinquefasciatus. topical application method, LD50(pg/female adult) ( Laboratory strain is a susceptible strain) (reproduced from [3])...

Table 2 Knockdown efficacy of Metofluthrin coil against Culex pipiens pallens (laboratory strain) by large chamber free-flying method...

Provasoli L, Pinter IJ (1980) Bacteria induced polymorphism in an axenic laboratory strain of Ulva lactuca. J Phycol 16 196-201... 

Anker,3 5 using isotope tracer technique, found in a mixed laboratory strain of rats (Wistar) no significant conversion of pyruvic acid to acetic acid. This was in contrast to the results obtained with the Sprague-Dawley strain of rats in which either such a conversion did take place or else pyruvic acid was utilized directly for acetylation. Exactly what constitutes the enzymic difference between the two strains is not known, but it is clear that a striking and potentially important difference exists. From the genetic standpoint one should not expect precisely the same metabolic results from rats of different strains or even from individual rats within the same strain, but the difference here reported is perhaps more fundamental than one might anticipate. If this difference is real, presumably other differences exist which have not been looked for, and one should be extremely careful about accepting the results from one strain as applicable to another. 

More recent investigations on the antimycobacterial activity of pamamycin-607 (lb) on 25 independent M. tuberculosis clinical isolates (either susceptible, mono-, or multiresistant to the first line antituberculous drugs) established minimum inhibitory concentrations MICjoo in the range of 1.5-2.0 pg/ml, while the MICjoo of lb for a bioluminescent laboratory strain of M. tuberculosis (H37Rv) was determined as 0.55 pg/ml [3a]. Parallel studies on the effect of lb on the cell cycle distribution of human (HL-60) cells by flow cytometry indicated no... 

The DNA or cDNA library is then introduced into a preparation of bacterial host cells. Usually, the first host selected is a laboratory strain of E. coli which has been grown and pretreated with inorganic salts to make uptake of DNA easier. The ability to take up foreign DNA is called competence, cells which have been specially prepared for the purpose are called competent cells. Other methods to transfer DNA into cells include electroporation (application of an external electric field to permeabUize the cell wall), transfection (where a recombinant bacterial virus is used to transfer the DNA to the target cell) or ballistic methods (by using DNA-coated particle projectiles). The last method has been used to introduce foreign DNA into plant cells and mammalian cells. 

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