Immune responses to DNA vaccines

DNA vaccines, based on plasmid vectors expressing an antigen under the control of a strong promoter, have been shown to induce protective immune responses to a number of pathogens, including viruses, bacteria and parasites. They have also displayed efficacy in treatment or prevention of cancer, allergic diseases and autoimmunity. Immunologically, DNA vaccines induce a full spectrum of immune responses that include cytolytic T cells, T helper cells and antibodies. The immune response to DNA vaccines can be enhanced by genetic engineering of the antigen to facilitate its presentation to B and T cells. Furthermore, the immune response can be modulated by genetic adjuvants in the form of vectors expressing biologically active determinants or by more traditional adjuvants that facilitate uptake of DNA into cells. The ease of genetic manipulation of DNA vaccines invites their use not only as vaccines but also as research tools for immunologists and microbiologists. Received 26 October 1998; received after revision 3 December 1998; accepted 3 December 1998     

Asteroseismology: oscillations on the star Procyon

Stars are spheres of hot gas whose interiors transmit acoustic waves very efficiently. Geologists learn about the interior structure of Earth by monitoring how seismic waves propagate through it and, in a similar way, the interior of a star can be probed using the periodic motions on the surface that arise from such waves. Matthews et al. claim that the star Procyon does not have acoustic surface oscillations of the strength predicted. However, we show here, using ground-based spectroscopy, that Procyon is oscillating, albeit with an amplitude that is only slightly greater than the noise level observed by Matthews et al. using spaced-based photometry.     

Different methotrexate effects in cultured normal and leukaemic human leukocytes

Summary Evidence is presented that the use of 2 different culture media, with or without methionine, can help to distinguish between normal and leukaemic methotrexate (MTX)-sensitive cells derived from chronic myeloid leukaemia patients. During the blast crisis MTX assays may help directly in the diagnostics of lymphoid involvement.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.4.Acknowledgments. We are indebted to Prof. Zofia Zieliska, Dept. of Cell Biochemistry, M. Nencki Institute of Experimental Biology PAN for providing the 5-methyltetrahydrofolate and for advice in these studies.     

Cooperative interactions between odorant-binding proteins of Anopheles gambiae

To understand olfactory discrimination in Anopheles gambiae, we made six purified recombinant OBPs and investigated their ligand-binding properties. All OBPs were expressed in bacteria with additional production of OBP47 in the yeast Kluveromyces lactis. Ligand-binding experiments, performed with a diverse set of organic compounds, revealed marked differences between the OBPs. Using the fluorescent probe N-phenyl-1-naphthylamine, we also measured the binding curves for binary mixtures of OBPs and obtained, in some cases, unexpected behaviour, which could only be explained by the OBPs forming heterodimers with binding characteristics different from those of the component proteins. This shows that OBPs in mosquitoes can form complexes with novel ligand specificities, thus amplifying the repertoire of OBPs and the number of semiochemicals that can be discriminated. Confirmation of the likely role of heterodimers was demonstrated by in situ hybridisation, suggesting that OBP1 and OBP4 are co-expressed in some antennal sensilla of A. gambiae.     

Common antigenicity between a human thymic epithelial cell product and a thymus-dependent serum factor

Summary Specific immunofluorescence of human thymic epithelial cytoplasm was obtained with antibodies to supernatant of thymic epithelial cultures, and with anti-prealbumin antibodies. These antibodies also reacted with normal serum but not with serum from Di George patients. The data indicates that thymic epithelium and a component of the prealbumin fraction of normal serum share a common antigen believed to be thymic hormone.Acknowledgment. The authors wish to thank Mrs Francine Rivard and Claire Prévost for technical assistance and Dr A.R.C. Dobell for human thymic material. This work was supported by the National Cancer Institute of Canada and the Medical Research Council of Canada.     

Transport of whole protein molecules from blood to saliva of a plant-bug

Zusammenfassung Es wird nachgewiesen, dass grosse Proteinmoleküle mit einem Molekulargewicht von 40 000 unverändert aus der Hämolymphe vonEumecopus in deren Speichel gelangen und damit ausgeschieden werden.     

The accessory salivary gland as the source of water in the saliva of hemiptera: Heteroptera

Summary Ablation of the accessory salivary glands of a pentatomid and of a coreid reduced quantitatively the flow of alkaline, watery saliva that can be induced by topical application of pilocarpine.