New ontogenetic evidence on the septomaxilla ofTamandua andCholoepus (Mammalia,Xenarthra), with a reevaluation of the homology of the mammalian septomaxilla

An intramembranous ossification at the anterior end of the cartilaginous nasal capsule is described for the first time in prenatal specimens of the anteaterTamandua and the slothCholoepus and redescribed in prenatal specimens of the armadillosDasypus andZaedyus. From comparisons of this bone with the septomaxilla of monotremes and various Mesozoic mammals, it is concluded that (1) the bone inTamandua andCholoepus is homologous with the central part (processus ascendens) of the bone inDasypus, Zaedyus, and other armadillos and (2) the xenarthran processus ascendens, in turn, is homologous with the central part of the septomaxilla of monotremes and various Mesozoic mammals. Therefore, the bone in question in xenarthrans is a true septomaxilla. It is further concluded that the armadillo septomaxilla has two neomorphic components: a lamina palatina beneath the cartilaginous nasal floor and a processus intrafenestralis extending rostrally into the nasal fossa.     

Inhibition of CD26/dipeptidyl peptidase IV enhances CCL11/eotaxin-mediated recruitment of eosinophils in vivo

Chemokines mediate the recruitment of leukocytes to the sites of inflammation. N-terminal truncation of chemokines by the protease dipeptidyl peptidase IV (DPPIV) potentially restricts their activity during inflammatory processes such as allergic reactions, but direct evidence in vivo is very rare. After demonstrating that N-terminal truncation of the chemokine CCL11/eotaxin by DPPIV results in a loss of CCR3-mediated intracellular calcium mobilization and CCR3 internalization in human eosinophils, we focused on the in vivo role of CCL11 and provide direct evidence for specific kinetic and rate-determining effects by DPPIV-like enzymatic activity on CCL11-mediated responses of eosinophils. Namely, it is demonstrated that i.v. administration of CCL11 in wild-type F344 rats leads to mobilization of eosinophils into the blood, peaking at 30 min. This mobilization is significantly increased in DPPIV-deficient F344 rats. Intradermal administration of CCL11 is followed by a dose-dependent recruitment of eosinophils into the skin and is significantly more effective in DPPIV-deficient F344 mutants as well as after pharmacological inhibition of DPPIV. Interestingly, CCL11 application leads to an up-regulation of DPPIV, which is not associated with negative feedback inhibition via DPPIV-cleaved CCL11((3-74)). These findings demonstrate regulatory effects of DPPIV for the recruitment of eosinophils. Furthermore, they illustrate that inhibitors of DPPIV have the potential to interfere with chemokine-mediated effects in vivo including but not limited to allergy.     

The tumorigenicity of mouse embryonic stem cells and in vitro differentiated neuronal cells is controlled by the recipients' immune response

Embryonic stem (ES) cells have the potential to differentiate into all cell types and are considered as a valuable source of cells for transplantation therapies. A critical issue, however, is the risk of teratoma formation after transplantation. The effect of the immune response on the tumorigenicity of transplanted cells is poorly understood. We have systematically compared the tumorigenicity of mouse ES cells and in vitro differentiated neuronal cells in various recipients. Subcutaneous injection of 1x10(6) ES or differentiated cells into syngeneic or allogeneic immunodeficient mice resulted in teratomas in about 95% of the recipients. Both cell types did not give rise to tumors in immunocompetent allogeneic mice or xenogeneic rats. However, in 61% of cyclosporine A-treated rats teratomas developed after injection of differentiated cells. Undifferentiated ES cells did not give rise to tumors in these rats. ES cells turned out to be highly susceptible to killing by rat natural killer (NK) cells due to the expression of ligands of the activating NK receptor NKG2D on ES cells. These ligands were down-regulated on differentiated cells. The activity of NK cells which is not suppressed by cyclosporine A might contribute to the prevention of teratomas after injection of ES cells but not after inoculation of differentiated cells. These findings clearly point to the importance of the immune response in this process. Interestingly, the differentiated cells must contain a tumorigenic cell population that is not present among ES cells and which might be resistant to NK cell-mediated killing.     

Effects of UV-absorbing plastic films on greenhouse whitefly (Homoptera: Aleyrodidae)

Studies were conducted to investigate the effects of ultraviolet (UV)-absorbing plastic films on the orientation and distribution behavior of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). In field experiments, small tunnels were constructed and covered with either an UV-transmitting (Thermilux) or UV-absorbing (K-Rose) plastic film. Results show that significantly more whiteflies were recorded in the tunnels with high compared with those with low UV intensities. Moreover, whitefly penetration and dispersion were less inside the UV-deficient tunnels. These results suggest that the type of plastic film used for greenhouse covers may have a significant influence on both the initial immigration and distribution of T. vaporariorum into greenhouses. The possibilities of using UV-absorbing plastic films for whitefly integrated pest management in greenhouses are discussed.     

Heat shock protein 70 is able to prevent heat shock-induced resistance of target cells to CTL

Heat shock or transfection with heat shock protein 70 (Hsp70) genes has been shown to protect tumor cell lines against immune mechanisms of cytotoxicity. We have reported previously that heat shock confers resistance to CTL in the rat myeloma cell line Y3 that is Hsp70 defective. Evidence is now presented that Hsp70 is able to prevent the induction of the resistant phenotype. In Con A-stimulated lymphocytes and in lymphocyte x Y3 somatic cell hybrid clones a severe, non-Hsp70-inducing heat shock elicits resistance to CTL in contrast to a heat shock that results in Hsp70 expression. Thus, Hsp70 expression appears to be negatively associated with the development of resistance. Furthermore, loading of Y3 cells with recombinant Hsp70 protein before heat shock is able to prevent resistance. Because apoptosis induced in Y3 cells by heat shock is not affected, Hsp70 appears to interfere selectively with the CTL-induced lethal pathway that is found to be calcium but not caspase dependent. It is suggested that after heat shock Hsp70 enhances the CTL-induced apoptotic pathway by chaperoning certain proteins in the target cell that are involved in the execution of cell death. Thus, although shown to confer protection against many cytotoxic mechanisms, Hsp70 does not appear to be generally cytoprotective. This observation could also be of relevance when interpreting the effectiveness of tumor immunity.     

Measuring polarization changes in the human outer retina with polarization‐sensitive optical coherence tomography

Morphological changes in the outer retina such as drusen are established biomarkers to diagnose age‐related macular degeneration. However, earlier diagnosis might be possible by taking advantage of more subtle changes that accompany tissues that bear polarization‐altering properties. To test this hypothesis, we developed a method based on polarization‐sensitive optical coherence tomography with which volumetric data sets of the macula were obtained from 10 young (<25 years) and 10 older (>54 years) subjects. All young subjects and 5 of the older subjects had retardance values induced by the retinal pigment epithelium and Bruch's membrane (RPE‐BM) complex that were just above the noise floor measurement (5°‐13° at 840 nm). In contrast, elevated retardance, up to 180°, was observed in the other 5 older subjects. Analysis of the degree of polarization uniformity (DOPU) demonstrates that reduced DOPU (<0.4) in the RPE is associated with elevated double pass phase retardation (DPPR) below the RPE‐BM complex, suggesting that the observed elevated DPPR in older subjects is the result of increased scattering or polarization scrambling. Collectively, our measurements show that the outer retina can undergo dramatic change in its polarization properties with age, and in some cases still retain its clinically normal appearance.      

Glutathione protection against dive-associated ischemia/reperfusion in ringed seal tissues

Ischemia/reperfusion is a potentially hazardous condition that increases reactive oxygen species (ROS) production and oxidative damage. Seals of the phocid family experience repetitive episodes of ischemia/reperfusion during and after a dive as a consequence of preferential distribution of blood flow to the central nervous system and reduction or elimination of perfusion in most vascular beds. Previous studies showed that ROS production is higher in ringed seal than in domestic pig tissues as a direct consequence of the ischemia/reperfusion associated with the diving response; however, oxidative damage is not related to this high ROS production. Apparently, antioxidant enzyme activities participate in the antioxidant protection in ringed seal tissues. In the present study we addressed the potential antioxidant protection of the glutathione system against dive-induced ischemia/reperfusion in ringed seal tissues. Total glutathione (GSH-Eq = GSH + 2GSSG), glutathione (GSH) and glutathione disulfide (GSSG), the ratio GSSG:GSH-Eq, the activities of the enzymes glutathione disulfide reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH), as well as lipid peroxidation (TBARS) and carbonyl proteins, were measured in ringed seal and domestic pig heart, kidney, liver, lung and muscle samples. In heart, kidney, lung and muscle GSH-Eq and GSH content was higher in seal than in pig (p < 0.05). GSSG content was higher in seal than in pig heart kidney, liver and muscle (p < 0.05). GR and G6PDH activities were higher in all seal than in pig tissues (p < 0.05). GSSG:GSH-Eq ratio was higher in pig than in seal heart, and lung (p < 0.05). TBARS content was higher in pig than in seal lung (p < 0.05). Higher content of carbonyl proteins was present in pig than in seal heart, kidney, liver and muscle (p < 0.05). These results suggest that the glutathione levels and the activity of enzymes involved in its recycling are efficient mechanisms that ameliorate protein and lipid oxidative damage and protect ringed seal tissues against dive-induced ischemia/reperfusion.     

Human Induced Pluripotent Stem Cells Are Targets for Allogeneic and Autologous Natural Killer (NK) Cells and Killing Is Partly Mediated by the Activating NK Receptor DNAM-1

Human induced pluripotent stem cells (hiPSCs) could be used to generate autologous cells for therapeutic purposes, which are expected to be tolerated by the recipient. However, iPSC-derived grafts are at risk of giving rise to teratomas in the host, if residuals of tumorigenic cells are not rejected by the recipient. We have analyzed the susceptibility of hiPSC lines to allogeneic and autologous natural killer (NK) cells. IL-2-activated, in contrast to resting NK cells killed hiPSC lines efficiently (P=1.69x10^-39). Notably, the specific lysis of the individual hiPSC lines by IL-2-activated NK cells was significantly different (P=1.72x10^-6) and ranged between 46 % and 64 % in ⁵¹Cr-release assays when compared to K562 cells. The hiPSC lines were killed by both allogeneic and autologous NK cells although autologous NK cells were less efficient (P=8.63x10^-6). Killing was partly dependent on the activating NK receptor DNAM-1 (P=8.22x10^-7). The DNAM-1 ligands CD112 and CD155 as well as the NKG2D ligands MICA and MICB were expressed on the hiPSC lines. Low amounts of human leukocyte antigen (HLA) class I proteins, which serve as ligands for inhibitory and activating NK receptors were also detected. Thus, the susceptibility to NK cell killing appears to constitute a common feature of hiPSCs. Therefore, NK cells might reduce the risk of teratoma formation even after autologous transplantations of pluripotent stem cell-derived grafts that contain traces of pluripotent cells.