SummaryIn Drosophila, normal and transformed cells compete with each other for survival in a process called cell competition. However, it is not known whether comparable phenomena also occur in mammals. Scribble is a tumor suppressor protein in Drosophila and mammals. In this study we examine the interface between normal and Scribble-knockdown epithelial cells using Madin-Darby Canine Kidney (MDCK) cells expressing Scribble short hairpin RNA (shRNA) in a tetracycline-inducible manner. We observe that Scribbleknockdown cells undergo apoptosis and are apically extruded from the epithelium when surrounded by normal cells. Apoptosis does not occur when Scribble-knockdown cells are cultured alone, suggesting that the presence of surrounding normal cells induces the cell death. We also show that death of Scribble-knockdown cells occurs independently of apical extrusion. Finally, we demonstrate that apoptosis of Scribble-knockdown cells depends on activation of p38 mitogen-activated protein kinase (MAPK). This is the first demonstration that an oncogenic transformation within an epithelium induces cell competition in a mammalian cell culture system.

The protein Pal (peptidoglycan-associated lipoprotein) is anchored in the outer membrane (OM) of Gram-negative bacteria and interacts with Tol proteins. Tol-Pal proteins form two complexes: the first is composed of three inner membrane Tol proteins (TolA, TolQ and TolR); the second consists of the TolB and Pal proteins linked to the cell's OM. These complexes interact with one another forming a multiprotein membrane-spanning system. It has recently been demonstrated that Pal is essential for bacterial survival and pathogenesis, although its role in virulence has not been clearly defined. This review summarizes the available data concerning the structure and function of Pal and its role in pathogenesis.

Very little is known about the effects of an organic or conventional diet on animal physiology and health. Here, we report the effect of contrasting crop protection (with or without chemosynthetic pesticides) and fertilization (manure or mineral fertilizers) regimes on feed composition and growth and the physiological parameters of rats. The use of manure instead of mineral fertilizers in feed production resulted in lower concentrations of protein (18.8 vs 20.6%) and cadmium (3.33 vs 4.92 μg/100 g) but higher concentrations of polyphenols (1.46 vs 0.89 g/100 g) in feeds and higher body protein (22.0 vs 21.5%), body ash (3.59 vs 3.51%), white blood cell count (10.86 vs 8.19 × 10³/mm³), plasma glucose (7.23 vs 6.22 mmol/L), leptin (3.56 vs 2.78 ng/mL), insulin-like growth factor 1 (1.87 vs 1.28 μg/mL), corticosterone (247 vs 209 ng/mL), and spontaneous lymphocyte proliferation (11.14 vs 5.03 × 10³ cpm) but lower plasma testosterone (1.07 vs 1.97 ng/mL) and mitogen stimulated proliferation of lymphocytes (182 vs 278 × 10³ cpm) in rats. There were no main effects of crop protection, but a range of significant interactions between fertilization and crop protection occurred.

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