Normal thymic cortical epithelial cells developmentally regulate the expression of a B-lineage transformation-associated antigen

Nonlymphoid, stromal cells in the mouse thymus are believed to be important in T cell maturation and have been proposed to play a central role in the acquisition of major histocompatibility complex (MHC) restriction and self-tolerance by maturing thymocytes. Both cortical and medullary epithelial cells in the thymus express high levels of class II (A) major histocompatibility antigens (MHC Ags). We show here that a specific subset of these A^– epithelial cells express a transformation-associated antigen (6C3Ag) found previously on the surfaces of Abelson murine leukemia virus-transformed pre-B cells and on those bone marrow-derived stromal cell clones which support normal and preneoplastic pre-B cell proliferation. Among solid lymphoid organs, only the thymus contains 6C3Ag¹ cells and within the thymus, this antigen is found exclusively on A^– epithelial cells in cortical regions. It is striking that the expression of the 6C3Ag on thymic epithelium is developmentally regulated, suggesting a role for this lymphostromal antigen in the maturation of the thymic microenvironment.     

Effect of hyperthermia on growth of Ehrlich ascites tumor cells

Hyperthermic treatment at 43 degrees C suppressed the growth of Ehrlich ascites tumor (EAT) cells in vitro. Incubation of EAT cells at 43 degrees C for as little as 1.5 h totally abolished the transplantability of the tumor. At the same time, the rate of cellular glucose uptake, the density of glucose transporter on the cells as well as the extent of thymidine, uridine and leucine incorporation were significantly reduced.     

Olfactory coding by lepidopterous larvae

Extracellular electrophysiological recording from olfactory receptors in the antennae of tobacco hornworm larvae (Manduca sexta (Johan.)) has revealed that cells respond differentially to different odors by changing latency, rate of increase of frequency of firing, rate of adaptation, and alternation of frequency increase and decrease. The resulting temporal patterns of spike activity could function as a code to allow for discrimination among various plant odors.

---

Zusammenfassung Extrazelluläre elektrophysiologische Erregungsableitungen von Geruchsrezeptoren in den Antennen von Tabakschwärmer-Raupen (Manduca sexta (Johan.)) ergaben, daß die Zellen auf verschiedene Duftstoffe unterschiedlich mit Änderung der Latenzzeit, der Zunahmerate der Erregungsfrequenz, der Anpassungsrate sowie der Änderung der Frequenz-Zunahme und-Abnahme reagieren. Die sich daraus ergebenden Zeitmuster der Spike-Aktivität könnten als Code dienen und so die Unterscheidung zwischen verschiedenen Pflanzendüften ermöglichen.

---

---

This research was supported by National Science Foundation Grant GB-1472.