Generation of Mouse Small Intestinal Epithelial Cell Lines That Allow the Analysis of Specific Innate Immune Functions

Cell lines derived from the small intestine that reflect authentic properties of the originating intestinal epithelium are of high value for studies on mucosal immunology and host microbial homeostasis. A novel immortalization procedure was applied to generate continuously proliferating cell lines from murine E19 embryonic small intestinal tissue. The obtained cell lines form a tight and polarized epithelial cell layer, display characteristic tight junction, microvilli and surface protein expression and generate increasing transepithelial electrical resistance during in vitro culture. Significant up-regulation of Cxcl2 and Cxcl5 chemokine expression upon exposure to defined microbial innate immune stimuli and endogenous cytokines is observed. Cell lines were also generated from a transgenic interferon reporter (Mx2-Luciferase) mouse, allowing reporter technology-based quantification of the cellular response to type I and III interferon. Thus, the newly created cell lines mimic properties of the natural epithelium and can be used for diverse studies including testing of the absorption of drug candidates. The reproducibility of the method to create such cell lines from wild type and transgenic mice provides a new tool to study molecular and cellular processes of the epithelial barrier.     

Characteristics of aSerratia plymuthica isolate from plant rhizospheres

An isolate (G15) of a bacterium, frequently isolated from roots of various plant species, was identified asSerratia plymuthica. At low temperature (viz. 2–8°C), the studied isolated readily produced a red pigment which proved useful in recognizing the bacteria on reisolation. In laboratory tests it exhibited strong antagonism againstBotrytis cinerea andGerlachia nivalis and moderate antagonism againstRhizoctonia solani, Fusarium culmorum andPythium sp. The bacterium significantly increased growth of lettuce plants when applied to the roots under non-sterile conditions in greenhouse tests. Various strains ofSerratia plymuthica are supposed to be common as rhizosphere bacteria under Swedish conditions.     

The effect of the 4B chromosomes of hexaploid wheat on the growth and regeneration of callus cultures

Summary Calli were initiated from immature embryos of nine lines of hexaploid wheat (Triticum aestivum L. em. Thell). These were the euploid lines Chinese Spring and Cappelle-Desprez, a line of Chinese Spring ditelocentric for the long arm of 4B, four substitution lines of Chinese Spring in which chromosome 4B has been replaced by its homologues from different wheat varieties and substituted into Chinese Spring and a substitution line of Besostaya I 4B into Cappelle-Desprez. The calli from these lines were found to differ in their growth rates and morphogenic and regenerative activities. The substitution of different 4B chromosomes into Chinese Spring significantly increased morphogenesis and shoot regeneration from callus. The potential for developing wheat lines with improved culture characteristics is discussed.     

Stimulation of arachidonic acid metabolism via phospholipase A2 by triethyl lead

Human blood platelet aggregation and the formation of icosanoids were studied in response to triethyl lead chloride (Et3PbCl). Concentrations higher than 75 microM stimulate platelets to aggregate, whereas low concentrations (less than or equal to 20 microM) caused platelet hypersensitivity to aggregating agents such as collagen or arachidonic acid. Incubation of suspensions of washed platelets with Et3PbCl resulted in a stimulated liberation and subsequent metabolism of arachidonic acid. This response was dependent on the concentration of Et3PbCl and the incubation time. Using low concentrations of Et3PbCl and up to 3 h of incubation, the lipoxygenase product 12-hydroxy-5,8,10,14-icosatetraenoic acid was the major metabolite. Under normal conditions, however, stimulation of platelets with collagen, thrombin, or arachidonic acid leads to higher amounts of the cyclooxygenase products 12-hydroxy-5,8,10-heptadecatrienoic acid and thromboxane B2. The aggregation of human platelets induced by Et3PbCl was inhibited by three different drugs: acetylsalicylic acid, forskolin and quinacrine; but only quinacrine could prevent the liberation of arachidonic acid and the appearance of its metabolites. These specific effects of the inhibitors on Et3PbCl-stimulated platelets as well as the differences in the pattern of arachidonic acid metabolites and phosphatidic acid suggest a direct stimulatory action of Et3PbCl on platelet phospholipase A2.     

Water, temperature and life

Cold is the fiercest and most widespread enemy of life on earth. Natural cold adaptation and survival are discussed in terms of physicochemical and biochemical water management mechanisms, relying on thermodynamic or kinetic stabilization. Distinctions are drawn between general effects of low temperature (chill) and specific effects of freezing. Freeze tolerance is a misnomer because tolerance does not extend to the cell fluids. Freezing is confined to the extracellular spaces where it acts as a means of protecting the cytoplasm against freezing injury. Freeze resistance depends on the phenomenon of undercooling, a survival mechanism that relies on the long-term maintenance of a thermodynamically highly unstable state. Correct water management involves many factors, among them the control of membrane composition and transmembrane osmotic equilibrium, the biosynthesis of compounds able to afford protection against injury through freeze desiccation and the availability (or inactivation) of biogenic ice nucleation catalysts.