Transcriptome changes and cAMP oscillations in an archaeal cell cycle

Background The cell cycle of all organisms includes mass increase by a factor of two, replication of the genetic material, segregation of the genome to different parts of the cell, and cell division into two daughter cells. It is tightly regulated and typically includes cell cycle-specific oscillations of the levels of transcripts, proteins, protein modifications, and signaling molecules. Until now cell cycle-specific transcriptome changes have been described for four eukaryotic species ranging from yeast to human, but only for two prokaryotic species. Similarly, oscillations of small signaling molecules have been identified in very few eukaryotic species, but not in any prokaryote. Results A synchronization procedure for the archaeon Halobacterium salinarum was optimized, so that nearly 100% of all cells divide in a time interval that is 1/4th of the generation time of exponentially growing cells. The method was used to characterize cell cycle-dependent transcriptome changes using a genome-wide DNA microarray. The transcript levels of 87 genes were found to be cell cycle-regulated, corresponding to 3% of all genes. They could be clustered into seven groups with different transcript level profiles. Cluster-specific sequence motifs were detected around the start of the genes that are predicted to be involved in cell cycle-specific transcriptional regulation. Notably, many cell cycle genes that have oscillating transcript levels in eukaryotes are not regulated on the transcriptional level in H. salinarum. Synchronized cultures were also used to identify putative small signaling molecules. H. salinarum was found to contain a basal cAMP concentration of 200 uM, considerably higher than that of yeast. The cAMP concentration is shortly induced directly prior to and after cell division, and thus cAMP probably is an important signal for cell cycle progression. Conclusions The analysis of cell cycle-specific transcriptome changes of H. salinarum allowed to identify a strategy of transcript level regulation that is different from all previously characterized species. The transcript levels of only 3% of all genes are regulated, a fraction that is considerably lower than has been reported for four eukaryotic species (6% - 28%) and for the bacterium C. crescentus (19%). It was shown that cAMP is present in significant concentrations in an archaeon, and the phylogenetic profile of the adenylate cyclase indicates that this signaling molecule is widely distributed in archaea. The occurrence of cell cycle-dependent oscillations of the cAMP concentration in an archaeon and in several eukaryotic species indicates that cAMP level changes might be a phylogenetically old signal for cell cycle progression

Nonseparability of Shared Intentionality

According to recent studies in developmental psychology and neuroscience, symbolic language is essentially intersubjective. Empathetically relating to others renders possible the acquisition of linguistic constructs. Intersubjectivity develops in early ontogenetic life when interactions between mother and infant mutually shape their relatedness. Empirical findings suggest that the shared attention and intention involved in those interactions is sustained as it becomes internalized and embodied. Symbolic language is derivative and emerges from shared intentionality. In this paper, we present a formalization of shared intentionality based upon a quantum approach. From a phenomenological viewpoint, we investigate the nonseparable, dynamic and sustainable nature of social cognition and evaluate the appropriateness of quantum interaction for modelling intersubjectivity

Regional knowledge transfer through public research spin-offs

New ventures stemming from universities and public research institutions have attracted increasing amounts of interest in the field of innovation politics over the last few years. Significant contributions to knowledge and technology transfer is expected from academic spin-offs, who are seen as transfer hubs, quickly creating exceptional products or processes and methods for economic use out of the newest scientific research results. Regions that are sites for research facilities are hoping that the new spin-offs will result in a strengthening of their own venture's innovative capabilities. First and foremost, this paper outlines representative empirical results of the founding of new academic spin-off ventures stemming from universities and public research institutions in germany. The main points of discussion will be the following: 1.) Presentation of the methods used to identify academic spin-offs, whose involvement with significant new research results, led to the establishment of the new venture. 2.) Relevance analysis of the regional proximity of scientific research institutions and their influence in the launch and continued relationship with new ventures. A geographical distance analysis is used. 3.) Identification of spin-off intensities in different industries, regions and categories of incubator institutions. 4.) Econometric analysis of the influence of success factors on spin-offs in comparison to other ventures with a corresponding business segment. This is performed with help of a semi-parametric control-group. 5.) Discussion on the usefulness of technology transfer hubs resulting from new spin-off ventures in the innovative development of regions. The data pool that is being presented here, consists of empirical results from a 1996 to 2000 ZEW survey of about 20,000 new ventures in technology or knowledge based industries and service sectors.

Quantification of ploidy in proteobacteria revealed the existence of monoploid, (mero-)oligoploid and polyploid species

Bacteria are generally assumed to be monoploid (haploid). This assumption is mainly based on generalization of the results obtained with the most intensely studied model bacterium, Escherichia coli (a gamma-proteobacterium), which is monoploid during very slow growth. However, several species of proteobacteria are oligo- or polyploid, respectively. To get a better overview of the distribution of ploidy levels, genome copy numbers were quantified in four species of three different groups of proteobacteria. A recently developed Real Time PCR approach, which had been used to determine the ploidy levels of halophilic archaea, was optimized for the quantification of genome copy numbers of bacteria. Slow-growing (doubling time 103 minutes) and fast-growing (doubling time 25 minutes) E. coli cultures were used as a positive control. The copy numbers of the origin and terminus region of the chromosome were determined and the results were in excellent agreement with published data. The approach was also used to determine the ploidy levels of Caulobacter crescentus (an alpha-proteobacterium) and Wolinella succinogenes (an epsilon-proteobacterium), both of which are monoploid. In contrast, Pseudomonas putida (a gamma-proteobacterium) contains 20 genome copies and is thus polyploid. A survey of the proteobacteria with experimentally-determined genome copy numbers revealed that only three to four of 11 species are monoploid and thus monoploidy is not typical for proteobacteria. The ploidy level is not conserved within the groups of proteobacteria, and there are no obvious correlations between the ploidy levels with other parameters like genome size, optimal growth temperature or mode of life

20% by 2020? Economy-wide impacts of energy efficiency improvement in Germany

The paper presents results of the implementation of an efficiency strategy in Germany until 2020 which is focused on cost-effective measures. The efficiency measures are calculated in bottom-up models and translated into a top-down macro-economic model. The comparison to a business as usual simulation shows some economy-wide rebound effects of about 17% of the overall energy savings. The analysis is limited to 2020. Given that an efficiency strategy is a long-term strategy, this puts the results on the rather conservative side. The results clearly show that improved energy efficiency results in a variety of positive effects on the economy and the environment. These range from reduced greenhouse gas emissions to improved competitiveness of firms and budget savings for consumers to economy wide impacts like additional employment and economic growth. Even the consideration of rebound effects did not change this picture significantly. Thus, exploiting the huge potential stemming from cost-effective efficiency measures should have high priority for the design of energy and climate policies.energy efficiency, bottom up scenario analysis, climate policy

Stellenwert farbdopplersonographischer Befunde in der (Differential-)Diagnose fokaler Milzläsionen: eine retrospektive Studie

Fokale Läsionen der Milz sind extrem selten und werden im Patientengut eines internistischen Ultraschall-Labors mit einer Häufigkeit von etwa 0,2 % bis 0,46 % beobachtet. Eine ätiologische Zuordnung ist häufig schwierig und erst in Verbindung mit klinischen Daten und dem sonographischen Verlauf möglich. Der Stellenwert der FKDS in der ätiologischen Zuordnung von fokalen Milzherden ist bisher unklar und wird kritisch beurteilt. Zu dieser Fragestellung liegen bisher keine methodenvergleichenden Studien vor. Zudem existieren keine umfassenden Daten zu FKDS-Befunden bei fokalen Milzläsionen. In der vorliegenden Arbeit wurden retrospektiv die Flußmuster 98 ätiologisch gesicherter fokaler Milzläsionen in der FKDS charakterisiert. Weiter wurde anhand der Ultraschallbilder von 63 Patienten, die von unterschiedlich erfahrenen Befundern ausgewertet wurden, ein Methodenvergleich zwischen B-Mode-Sonographie und FKDS angestellt. Die Ergebnisse der Arbeit können wie folgt zusammengefaßt werden: Es konnte gezeigt werden, daß ca. 68 % der fokalen Milzläsionen sich in der farbkodierten Duplexsonographie bzw. Power-Doppler-Sonographie mit fehlendem Flußsignal präsentierten. 15 % erschienen hypovaskularisiert, 8 % isovaskularisiert, 5 % wiesen ein hypervaskuläres Flußmuster auf und 3 % zeigten ein arteriovenöses Flußmuster. In der Darstellung des Flußsignals zeigte sich ein Unterschied zwischen den verwendeten Ultraschallgeräten: Mit neuerer Gerätechnik (ACUSON Sequoia) sank der Anteil als avaskulär detektierter Läsionen von 72,8 % (ACUSON 128) auf 63,2 %. Die diagnostische Treffsicherheit bei der Diagnose fokaler Milzläsionen im Ultraschall war sowohl in der B-Mode-Sonographie als auch in der FKDS von der Erfahrung des Befunders abhängig, d.h. erfahrene Befunder erzielten bessere Ergebnisse. Die diagnostische Treffsicherheit betrug beim unerfahrensten Befunder 32 % im B-Mode bzw. 35 % in der FKDS; die Werte des erfahrensten Befunders lagen bei 72 % (B-Mode) bzw. 75 % (FKDS). Im Gegensatz dazu wurde von den Befundern in 39,7 % bis 88,9 % der Fälle eine FKDS-Sonographie für die Diagnosesicherung für notwendig gehalten. Es konnte gezeigt werden, daß die durch die FKDS erhobenen zusätzlichen Informationen unabhängig von der Erfahrung der Befunder keine signifikante Verbesserung der diagnostischen Treffsicherheit (Veränderung zwischen ? 1,6 % und + 4,8 %) erbrachten. Der Stellenwert der FKDS für eine Diagnosesicherung wurde somit von den Befundern überschätzt. Die Bedeutung der FKDS in der (Differential-)Diagnose fokaler Milzläsionen ist insgesamt als niedrig einzuschätzen. Ein routinemäßiger Einsatz der FKDS im Rahmen der Sonographie der Milz ist nicht notwendig. Bei speziellen Fragestellungen wie Ausschluß bzw. Diagnose eines AV-Aneurysmas ermöglicht die FKDS eine rasche und sichere Diagnose. Möglicherweise wird die kontrastmittelunterstützte Sonographie die diagnostische Treffsicherheit bei fokalen Milzläsionen erhöhen

Reifungs- und Strukturbildungsprozesse bei Bindern mit wässrigen Alkalisilikat-Lösungen

Durch Reifungs- und Strukturbildungsprozesse kann es bei silikatischen und alumosilikatischen Bindern zu Rissbildung bei behinderter Verformung, Festigkeitsverlust und somit Verlust der Dauerhaftigkeit kommen. Die Bewertung dieser Prozesse erfolgt an silikatischen Materialien mit einem Ausblick auf die alumosilikatischen Binder

Maturation and Structure Formation Processes in Binders with Aqueous Alkali-Silicate Solutions

Maturation and structure formation processes can lead to crack formation in silicate and aluminosilicate binders (e.g. for coating materials...) through restricted deformation, loss of strength and thus to loss of durability. These processes are evaluated with silicate materials with an outlook on aluminosilicate binders