A novel fluorescent tracer for visualizing coupled cells in neural circuits of living tissue.

Gap junctions have diverse roles in a wide variety of tissues and have recently become a subject of intense investigation in neural circuits where synchrony and oscillations may play an important part. In circuits where gap junctions are present, the possibility arises of identifying intercommunicating cells via introduction of tracer into one cell and observing its spread into its coupled neighbors. Staining the coupled cells by this means opens the door to many vital techniques including paired-cell electrophysiology, RT-PCR, and morphological characterization of previously unknown coupled cells. Tracers commonly used at the present time are not generally suitable for these purposes in many tissues, including neurons. This paper describes how a fluorescent nuclear tracer, Po-pro-1, can be used to visualize coupled cells in several types of retinal neurons thought to be comprised of different connexin proteins including Cx36, Cx45, Cx50, and Cx57.     

Rapid method of visualizing endothelium in unfixed tissue

An express method of visualization of endotheliocytes has been described. It is based on the combined use of vital dye-thioflavin and silver nitrate. The method requires no fixation, "h?utchen" preparation and scanning electron microscopy. It is very simple, needs no special training or facilities and allows visualization of the endothelium already 2 min after the tissue is obtained.     

Compraison of mycoplasmas associated with human tumors, leukemia, and tissue cultures

Leach, R. H. (Wellcome Research Laboratories, Beckenham, Kent, England), and M. Butler. Comparison of mycoplasmas associated with human tumors, leukemia, and tissue cultures. J. Bacteriol. 91:934-941. 1966.-Mycoplasmas originally isolated by various workers from tissue cultures prepared from or inoculated with tumor or leukemic cells fell into four groups; each related to existing species or serotypes. These were Mycoplasma pulmonis, M. fermentans, M. hominis, and the GDL serotype, the last two being well known as contaminants of uninoculated cell lines. All the test strains were able to grow well in certain tissue cultures, and some caused cytopathic effects and acidity. These observations are discussed in terms of the relationship of these strains to the malignant tissues with which they were originally associated. The variable results obtained in certain biological tests on these strains emphasized the need for standardization of the conditions under which such tests may be employed to assist in identification of Mycoplasma species.     

Lipids in plant tissue cultures. III. Very long-chain fatty acids in the lipids of callus cultures and suspension cultures

The lipids in plant tissue cultures contain in addition to the common saturated and unsaturated fatty acids even- and odd-numbered fatty acids having chain-lengths up to 26 carbon atoms.     

Lipids in plant tissue cultures IV. The characteristic patterns of lipid classes in callus cultures and suspension cultures

Lipids from callus cultures and suspension cultures of higher plants constitute 5 to 8% of the dry tissue's weight.The predominant lipid classes are the sterols, steryl esters, steryl glycosides and esterified steryl glycosides. Considerable amounts of a variety of sterylglycolipids, whose structures are not completely elucidated, are also present. Triglycerides and phospholipids occur in small proportions, whereas monogalactosyl diglycerides, digalactosyl diglycerides and sulfoquinovosyl diglycerides are present only in traces, if at all.β-Sitosterol is the predominant constituent sterol, stigmasterol and campesterol as well as a variety of as yet unidentified sterols occur in smaller proportions. The major constituent fatty acids are palmitic, oleic, linoleic and linolenic acids. Saturated very long-chain fatty acids are found in smaller proportions. Unusual fatty acids, such as epoxy acids, which occur in the seed lipids of certain plants, are not found in tissue cultures derived from these plants. Clucose and traces of galactose are the only sugars obtained by acid hydrolysis of the glycolipids occurring in plant tissue cultures.     

Lipids in plant tissue cultures. II. Unusual fatty acids in lipids of Hydnocarpus anthelminthica cultures

The lipids in callus cultures of Hydnocarpus anthelminthica were studied after 60, 160 and 460 days of growth. In each of the cultures the lipid classes usually found in plant tissue cultures were detected. With increasing age of the cultures the total lipid content as well as the proportions of triglycerides decreased. The major constituent fatty acids of the total lipids were palmitic and linoleic acids. Small amounts of cyclopentenyl fatty acids were also present. The proportions of saturated straight-chain fatty acids increased with the age of the cultures whereas the proportions of monounsaturated straight-chain fatty acids decreased. Only small changes were observed with polyunsaturated fatty acids. The content of cyclopentenyl fatty acids rose with the age of the cultures. The monounsaturated straight-chain fatty acids consisted of mixtures of isomers whose composition changed with the age of the cultures. In contrast, the polyunsaturated straight-chain fatty acids belonged exclusively to the Δ9 series, regardless of the age of the cultures.     

Pleuropneumonialike organisms in tissue cultures

Of 55 continuous cell lines 32 gave growth of P.P.L.O. whereas 26 primary cell cultures were free from this contamination.Biochemical and serological typing proved that 31 of these 32 P.P.L.O. wereMycoplasma hominis I. One strain was identical with a recently described oralMycoplasma.It was demonstrated that insufficiently rigorous techniques tend to cause spreading of P.P.L.O. in tissue culture laboratories.There was no indication that either the sera or other ingredients of the media used might have introduced this contamination. HeLa cells, however, probably are the source.The minor differences between genital strains propagated in the laboratory, and tissue culture strains, are probably due to differences between the two media.By treatment of a contaminated cell line with serum againstM. hominis I a double infection with P.P.L.O. could be demonstrated. The cells were freed from the remaining P.P.L.O. by treatment with the serum against this strain.Contamination of cell lines withM. hominis I did not affect the growth rate of the wild poliovirus I strains tested, nor that of a Sabin type I strain. M. fermentans grows well in tissue cultures but has no cytopathic effect.M. salivarium cannot be propagated in ordinary tissue cultures unless Fildes extract, which contains catalase, is added. In cultures with this extractM. salivarium has a cytopathic effect.     

Organogenesis in pepper tissue cultures

Knowledge concerning in vitro growth and developmental responses of bell and chile peppers (Capsicum annuum L.) has been limited. Shoot and root organogenesis in cultures of seedling explants was restricted to primary cultures or those less than three months old under 12-and 16-h photoperiod at 25°C. Shoot organogenesis was extended to 5 months under continuous light at 25°C, and to 8 months under continuous light at 28.5°C. Murashige and Skoog basal media containing 0.05mg/l each of IAA and BA promoted shoot elongation and rooting of some explant sources, while 0.05-4 mg/l IAA with 10–50 mg/l BA promoted adventitious shoot bud formation. Glucose was superior to sucrose as the carbon source. Leaf discs collected from greenhouse-grown plants regenerated shoots for at least 2 months. Incubation environment, carbon source, explant source, growth regulator treatment and passage number were not independent variables as demonstrated by statistical analysis. The plant regeneration techniques described here have useful but limited applications, not extending to unorganized callus or cell suspension cultures.Journal article no. 1151 of the New Mexico Agricultural Experiment Station.     

A Java applet for visualizing protein-protein interaction.

A web applet for browsing protein-protein interactions was implemented. It enables the display of interaction relationships, based upon neighboring distance and biological function. AVAILABILITY: The Java applet is available at http://www.charite.de/bioinformatics     

Lipids in plant tissue cultures. VII: Heterotrophic and mixotrophic cell cultures of Chenopodium rubrum

Mixotrophic cell cultures of Chenopodium rubrum were found to synthesize 5 to 33 times more monogalactosyldiacylglycerols and 5 to 16 times more digalactosyldiacylglycerols than heterotrophic ones. The monogalactosyldiacylglycerols and digalactosyldiacylglycerols from mixotrophic cultures contained higher levels of linolenic acid as compared to heterotrophic cultures. It is concluded that the active synthesis of these galactolipids with high levels of constituent linolenic acid is associated with the onset of photosynthesis in plant cell cultures, as is the case in intact plants.     

Intestinal tissue and cell cultures

The culture of animal cells and tissues is a widely used technique in the field of cellular and molecular biology; one of the most interesting aspect being linked to the study of the mechanisms of cell differentiation. In the specific case of intestinal epithelial cells, various tissue culture technologies have proved to be important tools for the study of precise facets related to intestinal function, pathology and differentiation. Concerning this latter aspect, organ culture experiments have brought about interesting data on the hormonal or nutritional control of intestinal maturation. Nevertheless, the study of the precise mechanisms underlying epithelial proliferation and/or differentiation at the cellular level needs more adequate cell culture model systems. One of them has been described for two cell lines derived from human colonic adenocarcinomas, in which the cells can be induced to achieve enterocytic-like differentiation. Up to date, none of the continuous cell lines starting from normal undifferentiated cells have allowed generation of morphological or functional enterocytic polarity. In contrast, primary cell cultures which allow maintenance of a more physiological environment for the epithelial cells like contacts with their in vivo counterparts, mesenchymal cells or extracellular matrix molecules, have proved to be promising approaches.