Analysis of three marine fish cell lines by rapd assay

We tested the applicability of the random amplified polymorphic deoxyribonucleic acid (RAPD) analysis for identification of three marine fish cell lines FG, SPH, and RSBF, and as a possible tool to detect cross-contamination. Sixty commercial 10-mer RAPD primers were tested on the cell lines and on samples collected from individual fish. The results obtained showed that the cell lines could be identified to the correspondent species on the basis of identical patterns produced by 35-48% of the primers tested; the total mean similarity indices for cell lines versus correspondent species of individual fish ranged from 0.825 to 0.851, indicating the existence of genetic variation in these cell lines in relation to the species of their origin. Also, four primers, which gave a monomorphic band pattern within species/line, but different among the species/line, were obtained. These primers can be useful for identification of these cell lines and for characterization of the genetic variation of these cell lines in relation to the species of their origin. This supported the use of RAPD analysis as an effective tool in species identification and cross-contamination test among different cell lines.     

An In vitro assay useful to determine the potency of several bitter compounds

Gustducin and transducin are guanine nucleotide binding regulatory proteins (G proteins) expressed in taste receptor cells and implicated in transducing taste cell responses to certain compounds that humans consider bitter or sweet. These G proteins can be activated in vitro by taste receptor-containing membranes plus any of several bitter compounds. This activation can be monitored using limited trypsin digestion, sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Scanning of the autoradiograms enables one to quantitate the level of activation (defined as an activation index), obtain dose-response profiles and estimate the potency of the tastant. This assay may provide a useful substitute for, or adjunct to, the time-consuming human psychophysical analysis and costly animal studies typically used in taste sensory analysis. It may be used to identify and determine the concentration-response function of many bitter components of oral pharmaceuticals and food ingredients. A potential limitation of the assay is that only about half of all bitter compounds tested demonstrated in vitro activity, perhaps due to the presence of multiple transduction pathways. Nevertheless, the rapid throughput and microsample handling capability of this assay make it an ideal method to screen for high-potency bitterness inhibitors.     

Inter-laboratory comparison of cell lines for susceptibility to three viruses: VHSV, IHNV and IPNV.

Eleven European National Reference Laboratories participated in an inter-laboratory comparison of the susceptibility of 5 selected cell lines to 3 fish pathogenic viruses. The test included viral hemorrhagic septicaemia virus (VHSV); infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV), and the cell lines derived from bluegill fry (BF-2), chinook salmon embryo (CHSE-214), epithelioma papulosum cyprini (EPC), fathead minnow (FHM) and rainbow trout gonad (RTG-2). The results showed that for isolation of VHSV, BF-2 and RTG-2 cells performed equally well and had higher sensitivity compared to the other cell lines. For IHNV, EPC and FHM cells gave the best results, and for IPNV it was BF-2 and CHSE-214 cells. FHM cells showed the largest variability among laboratories, whereas EPC was the cell line showing the smallest variability.     

Approaches to the validation of animal test systems for assay of protective potency of BCG vaccines.

Three animal test systems, two in guinea-pigs and one in mice, have been examined to differentiate the ability of three BCG vaccines with respect to their ability to protect the animals against infection when challenged with virulent bacilli. One test system showed great promise and was examined in greater detail in order to explain the mechanism of protection. These studies are continuing in order to test a series of BCG vaccines that will be given to groups of children and their protective effect observed.     

In vitro scratch assay: a convenient and inexpensive method for analysis of cell migration in vitro

The in vitro scratch assay is an easy, low-cost and well-developed method to measure cell migration in vitro. The basic steps involve creating a "scratch" in a cell monolayer, capturing the images at the beginning and at regular intervals during cell migration to close the scratch, and comparing the images to quantify the migration rate of the cells. Compared to other methods, the in vitro scratch assay is particularly suitable for studies on the effects of cell-matrix and cell-cell interactions on cell migration, mimic cell migration during wound healing in vivo and are compatible with imaging of live cells during migration to monitor intracellular events if desired. Besides monitoring migration of homogenous cell populations, this method has also been adopted to measure migration of individual cells in the leading edge of the scratch. Not taking into account the time for transfection of cells, in vitro scratch assay per se usually takes from several hours to overnight.     

In vitro assays for new drug screening: comparison of a thymidine incorporation assay with the human tumor colony-forming assay

Because of technical limitations with the human tumor colony-forming assay (HTCFA), we determined the feasibility of using a thymidine incorporation assay (TIA) for new drug screening. Concordance between the TIA and the HTCFA was obtained (r = 0.840) with twenty coded compounds. Toxic agents without proven clinical efficacy were active in both assays, while non-toxic substances were inactive. Growth rates were higher with the TIA (75%) than with the HTCFA (45%), and the TIA could be completed in 6 days compared to 14-21 days with the HTCFA. We concluded that the TIA is a useful adjunct to in vivo tumor models for screening new anticancer agents.     

In vitro differentiation of the human osteosarcoma cell lines, HOS and KHOS.

The osteogenic potential of the two human osteosarcoma cell lines HOS and KHOS; a cell line produced by the transformation of the HOS cells by the Kirsten murine sarcoma virus, was studied in vitro. HOS cells cultured more than 2 weeks formed nodules composed of two morphologically distinct layers, an epithelial-like surface cell layer and a collagen-rich inner cell layer. Alkaline phosphatase (ALPase) activity occurred in the plasma membrane of the surface cell layer, and calcified substances developing along collagen fibers were detected in the collagen-rich inner cell layer. The calcified substances were further examined by analytical electron microscopy and were shown to be hydroxyapatite crystals. In contrast, there was neither ALPase nor the deposition of a calcified substance in the KHOS cells.     

In vitro infection of Cryptosporidium parvum to four different cell lines

To determine a suitable condition for in vitro infection model of Cryptosporidium parvum, four different cell lines, AGS, MDCK, HCT-8 and Caco-2, were used as host cell lines which were cultured at various concentrations of added supplements. These supplement include fetal bovine serum (FBS), sodium choleate, ascorbic acid, folic acid, calcium pantothenate, para-aminobenzoic acid and pyruvate and their effects on the cell lines which were infected with C. parvum were evaluated. The results of this study showed that the AGS cell line was most susceptible to C. parvum whereas the Caco-2 cells appeared to be least susceptible to C. parvum. In regards to the serum condition, 10% FBS was suitable for the growth of AGS and HCT-8 cells, and 1% FBS was good for the growth of the MDCK cells when they were inoculated with C. parvum. Vitamins had a positive effect on the AGS cells, and pyruvate also showed positive effects on all of the cell lines except for Caco-2. Modified medium for each cell line was prepared by adding appropriate amounts of each supplement which resulted in the highest parasite infection number. Modified media increased the number of parasites infected on AGS cells to 2.3-fold higher when compared to the control media. In this study, we found that the AGS cell line was a suitable host model for evaluating C. parvum in vitro study and the media contents for the optimal infection conditions were suggested.     

In vitro cultivation of Wolbachia in insect and mammalian cell lines

Wolbachia infecting the small brown planthopper, Laodelphax striatellus, were successfully maintained and cultivated in two insect and one mammalian cell lines. The bacteria with the planthopper ovary were introduced into the flasks with the cultures of the cell lines. The Wolbachia proliferated in mosquito (Aedes albopictus) and lepidopteran (Heliothis zea) cell lines and in the mouse cell line, L929. Proliferation of Wolbachia was confirmed by electron microscopy and quantitative polymerase chain reaction. This simple method for the cultivation of Wolbachia was applicable to other strains of Wolbachia, such as the one found in the lepidopteran eggs, and should facilitate fundamental and applied studies of this important group of microorganisms.     

Non-pertussis components of combination vaccines: problems with potency testing.

Vaccines comprising combinations of diphtheria, tetanus and pertussis (DTP) with Haemophilus influenzae type b polysaccharide-protein conjugate (Hib), inactivated poliomyelitis virus (IPV) and hepatitis B virus (HBV) are already available, and new combinations using acellular pertussis components in a triple vaccine (DTaP) are under development. Evidence to date has shown that control of the efficacy, safety and stability of combination vaccines cannot be based on information already available on the individual components or existing licensed formulations. Several examples of immunological interference between components of a combination vaccine have been observed both in clinical trials and in laboratory tests. Examples of these for D, T and Hib components in DTP and DTaP combinations have been investigated.     

In vitro assay for sex pheromone biosynthesis by the female yellow mealworm beetle and identification of a regulated step

Several pheromones are known to be involved in mediating the mating behavior of the yellow mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae). The only sex pheromone that has been identified to date in this species is the female-produced male attractant, 4-methylnonanol (MNol). The objective of this study was to develop an in vitro assay for the last biosynthetic step involved in MNol biosynthesis, the reduction of 4-methylnonanoic acid (MNA) to the corresponding pheromone product. In vitro assays were conducted by adding appropriate cofactors and radioactively labelled precursor. Radioactive pheromone product was separated from the radioactive precursor by column chromatography, and quantified through scintillation counting. The conversion of MNA to MNol was observed, and was comparable to that observed in vivo using the same radiolabelled substrate. In both the in vivo and in vitro assays, the (3)H-MNA was also converted to a nonpolar product, tentatively identified as a triacylglyerol (TAG) derivative. The reduction of (3)H-MNA to pheromone proceeded through the coenzyme A intermediate. Mature females reduced significantly more precursor to pheromone than the immature females and the males, both in vivo and in vitro, indicating that the reduction of MNA to MNol is a regulated step involved in pheromone production. Using the in vitro assay reported herein, studies are ongoing in our lab to purify and characterize the enzyme catalyzing the reduction.