Expression of tobacco genes for light-harvesting chlorophyll a/b binding proteins of photosystem II is controlled by two circadian oscillators in a developmentally regulated fashion

Light-induced expression of genes encoding the light-harvesting chlorophyll a/b binding proteins of photosystem II (Cab) was shown to be controlled by a circadian oscillator coupled to the red-light-absorbing plant photoreceptor phytochrome. Here we show that a red-light-insensitive oscillator is also involved in regulating the expression of the Cab genes. We provide evidence that germination leads, in a light-independent manner, to the setting and/or synchronization of endogenous oscillators and that it induces the expression of Cab genes in a circadian fashion. This circadian oscillator is not coupled to phytochrome, as it cannot be reset by red light for at least 44 h after sowing. Short red light pulses given between 12 and 44 h after sowing, however, induce new rhythms without perturbing the already free-running red-light-independent circadian oscillation. At this stage of development, the phytochrome-coupled and uncoupled circadian rhythms coexist. Both circadian rhythms are expressed and exhibit period lengths close to 24 h but are phased differently. At later stages of development (60 h or later after sowing), red light treatments synchronized these free-running rhythms and led to the appearance of a single new circadian oscillation. These data indicate that during early development the expression of single tobacco Cab genes, particularly expression of the Cab21 and Cab40 genes, is controlled in a developmentally dependent manner by two circadian oscillators

Functional genomics of calcium channels in human melanoma cells.

Ca(2+)-signaling of human melanoma is in the focus of intensive research since the identification of the role of WNT-signaling in melanomagenesis. Genomic and functional studies pointed to the important role of various Ca(2+) channels in melanoma, but these data were contradictory. In the present study we clearly demonstrate, in a number of different ways including microarray analysis, DNA sequencing and immunocytochemistry, that various human melanoma cell lines and melanoma tissues overexpress ryanodine receptor type 2 (RyR2) and express P2X(7) channel proteins as compared to melanocytes. These channels, although retain some of their usual characteristics and pharmacological properties, display unique features in melanoma cells, including a functional interaction between the two molecules. Unlike P2X(7), RyR2 does not function as a calcium channel. On the other hand, the P2X(7) receptor has an antiapoptotic function in melanoma cells, since ATP-activation suppresses induced apoptosis, while knock down of the gene expression significantly enhances that

National character does not reflect mean personality trait levels in 49 cultures

Most people hold beliefs about psychological characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, or stereotypes with or without a “ kernel of truth." We obtained national character ratings from 49 cultures and compared them to average personality scores of culture members as assessed by observer ratings and self-reports. National character ratings appeared to be reliable and valid measures, but they did not converge with assessed personality traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity