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Notch receptors participate in a conserved signaling pathway that controls the development of diverse tissues and cell types. In the present study we investigated the expression of four Notch genes in primary human osteoblasts and in human osteoblastic osteosarcoma cell line SaOS-2 by RT-PCR. We found a strong constitutive expression of Notch-1 and a weak constitutive expression of Notch-2 in both cell types. After stimulation with Dexamethasone or Vitamin D(3), two factors known to induce differentiation in osteogenic cells, both Notch receptors were downregulated, however, with a different time course. Notch-1 and Notch-2 showed a transient induction after 2 days and a decrease after 7 days in osteoblasts and after 28 days in SaOS-2 cells. Notch-4 expression could only be detected after stimulation with Dexamethasone and Vitamin D(3). However, in osteoblasts a transient induction after 2 days could be detected in osteoblasts, whereas Notch-4 expression increased after 14 and 28 days in SaOS-2 cells. In contrast, Notch-3 was not expressed in human osteoblasts and SaOS-2 osteosarcoma cells. These data show, that Notch genes are expressed in human osteoblastic cells and that the expression is differentially regulated upon stimulation with osteogenic factors.

The functions of the fields of the mammalian auditory cortex in sound perception and recognition are unknown. We used Fos (a protein of the inducible immediate-early gene c-fos) as a cellular marker of activated brain areas to show in the mouse (Mus domesticus) that sound is processed differentially in auditory cortical fields according to its actual significance in a behavioral context. Recognition, compared with perception of exactly the same sound, produced significantly less but well focused Fos-positive cells in a primary auditory cortical field and significantly more labeling in higher auditory and association fields. Thus, recognition means a state of distinctive spatial distribution of activity in auditory cortical fields with a predominance of activation in higher-order fields.

The aim of the present study was to detect differentially expressed genes in the human osteoblast-like osteosarcoma cell line SaOS-2 using non-radioactive RNA fingerprinting (RNA arbitrarily primed polymerase chain reaction, RAP-PCR). RNA was isolated at different time points from SaOS-2 cells grown with and without dexamethasone (DEX). By RAP-PCR we detected changes in band patterns of cells treated with DEX compared with untreated cells. PCR fragments further characterized and sequences from three of these gave perfect matches to the coding sequences of the human nucleophosmin gene B23, cDNA clone 4_c6 from P1 H25 and the human TRA1 gene, respectively. differential regulation of these genes in DEX-stimulated SaOS-2 cells could be demonstrated by RT-PCR.

Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex (AC) of the mouse and to characterize various fields within the AC. The AC of the left hemisphere covered a significantly larger (factor of 1.30) area compared to that of the right side. Based on best-frequency (BF) maps and other neuronal response characteristics to tone and noise bursts, five fields (primary auditory field, anterior auditory field, second auditory field, ultrasonic field, dorsoposterior field) and two small non-specified areas could be delimited on both hemispheres. The relative sizes of these fields and areas were similar on both sides. The primary and anterior auditory fields were tonotopically organized with counter running frequency gradients merging in the center of the AC. These fields covered BF ranges up to about 45 kHz. Higher BFs up to about 70 kHz were represented non-tonotopically in the separate ultrasonic field, part of which may be considered as belonging to the primary field. The dorsoposterior and second auditory fields were non-tonotopically organized and neurons had special response properties. These characteristics of the mouse AC were compared with auditory cortical maps of other mammals.