Generation of Transgenic Mice to Evaluate Promoter Activity and Specificity of Two Human Endogenous Retrovirus Long Terminal Repeats = Untersuchungen zur Promotor-Aktivität und -Spezifität von zwei Long Terminal Repeats humaner endogener Retroviren in transgenen Mäusen

Generation of Transgenic Mice to Evaluate Promoter Activity and Specificity of two Human Endogenous Retrovirus Long Terminal Repeats Human Endogenous Retrovirus Long Terminal Repeats (HERV-LTRs) comprise 1.8% of the human genome (52.7 Mb). These sequences contain all the signal structures necessary for the regulation of gene transcription, such as promoters, enhancers and transcription factor binding sites. There is evidence that HERV-LTRs regulate gene expression in tissue-specific manner. This potential could be used to drive the expression of therapeutic genes, delivered by retroviral vector systems, in a safe and efficient manner. The HERV-H-H6 LTR and the HERV-L LTR were chosen for the generation of transgenic mice. Their promoter activity and specificity had prior been tested in a luciferase expression vector in vitro (Schoen et al., 2001). HERV-L was cloned into a luciferase expression vector and HERV-H-H6 was inserted into a enhanced green fluorescent protein (EGFP) expression vector. Transgenic mice were generated by DNAmicroinjection into pronuclei of zygotes. One pBL-HERV-L transgenic line and four pEGFP-HERV-H-H6 transgenic lines were established and analyzed. While the HERV-L promoter was not active in transgenic animals, pEGFP-HERV-H-H6 was expressed in gonads of mice of two transgenic lines. As only a single, non-expressing transgenic line was available, HERV-L promoter activity and specificity could not be evaluated. Additional transgenic lines have to be established. Expression level and pattern of the HERV-H-H6 promoter indicate specificity for gonad tissue. Whether the HERV-H-H6 promoter activity is linked to steroid production in cells remains to be clarified. Evaluating promoter activity in transgenic mice in two different expression vectors is not exclusively about the promoters, but also involves knowledge about the reporter genes. Advantages and limits of current applications of both luciferase and EGFP (with focus on the EGFP gene) are described in REVIEW OF THE LITERATURE. The conjunction of EGFP with the HERV-H-H6 promoter is to be seen critically, as all published methods for detection of EGFP in mice are described with EGFP linked to strong promoters. Problems like autofluorescence in fluorescence microscopy might be encountered when weaker promoters, such as HERV-LTRs, drive EGFP expression.Untersuchungen zur Promotor-Aktivität und –Spezifität von zwei Long Terminal Repeats humaner endogener Retroviren in transgenen Mäusen 1.8% des humanen Genoms bestehen aus Long Terminal Repeats Humaner Endogener Retroviren (HERV-LTRs). Solche Sequenzen enthalten alle Strukturen, die für die Regulierung von Transkription benötigt werden: Promotoren, Enhancer and Bindungsstellen für Transkriptionsfaktoren. Es gibt Hinweise, daß HERV-LTRs die Expression von Genen gewebespezifisch regulieren können. Eingebaut in retrovirale Genfähren, könnten HERV-LTRs therapeutische Gene sicher und effizient aktivieren. Zur Generierung transgener Mäuse wurden der HERV-H-H6 LTR und der HERV-L LTR ausgewählt. Deren Promoter Eigenschaften, wie Aktivität und Gewebespezifität, waren bereits in vitro untersucht worden (Schoen et al., 2001). Der HERV-L LTR wurde in einen Luciferase Expressionsvektor und der HERV-H-H6 LTR in einen Enhanced Green Fluorescent Protein (EGFP) Expressionsvektor kloniert. Transgene Mäuse enstanden durch DNA-Mikroinjektion in den Vorkern von Zygoten. Eine pBL-HERV-L transgene Linie und vier pEGFP-HERV-H-H6 transgene Linien wurden gezüchtet und auf Integration sowie Expression der Genkonstrukte untersucht. Während der HERV-L Promoter keine Aktivität zeigte, war Expression von pEGFP-HERV-H-H6 in Keimdrüsen von Mäusen aus zwei transgenen Linien nachweisbar. Da für das Genkonstrukt pBL-HERV-L nur eine einzige, nicht-exprimierende transgene Linie aufgebaut werden konnte, können keine Aussagen über die Aktivität und Gewebespezifität des HERV-L Promoters getroffen werden. Zu diesem Zwecke müssten weitere pBL-HERV-L transgene Linien untersucht werden. Das Expressionsmuster des pEGFP-HERV-H-H6 Genkonstruktes, weißt auf eine mögliche Gewebespezifität für Keimdrüsen hin. Eine eventuelle Verknüpfung der Aktivität des HERV-H-H6 LTRs mit der Produktion von Steroidhormonen müsste weitergehend geklärt werden.Da in dieser Arbeit zwei unterschiedliche Reportergen Systeme in der Maus angewandt wurden, sind im Literaturteil Vorteile und Einschränkungen von aktuellen Nachweisverfahren beider Reportergene, mit Schwerpunkt EGFP, in Mausgewebe zusammengefasst. Die Verbindung von EGFP mit dem HERV-H-H6 Promoter ist als kritisch zu beurteilen: Alle beschriebenen Nachweisverfahren für EGFP in der Maus gründen auf Mausmodellen, in denen das EGFP von einem starken Promoter kontrolliert wurde. Bei potenziell schwächeren Promotoren, wie HERV-LTRs, können Probleme auftreten, wie z.B. Autofluoreszenz bei der Fluoreszenzmikroskopie

Foraminiferal test abnormalities in the western Baltic Sea

Abnormal tests were commonly found in recent benthic foraminiferal assemblages in two fjords of the Kiel Bay, the western Baltic Sea. We assessed 18 different types of abnormalities, which were classified into five groups: chamber, apertural, umbilical, coiling and test abnormalities. In both fjords, test abnormalities are over-represented in Ammonia beccarii and under-represented in Elphidium excavatum subspecies compared to their average proportions in the living assemblages. We found two species-specific abnormality types that occurred only in Ammonia beccarii: a bulla-like chamber covering the umbilicus and spiroconvex tests. In the outer Kiel and Flensburg Fjords, the highest frequencies of abnormal tests were associated with occasional salt-rich, bottom-water inflows from the Belt Sea. Based on the predominance of megalospheric specimens of living foraminifera, it is suggested that coincidence of salinity changes with a reproduction period might be harmful, especially for young individuals, leading to development of abnormal tests. On the other hand, pollution by heavy metals led to higher percentages of abnormal tests in the inner parts of both fjords. Our data show different relationships between abnormal tests and heavy metals in both fjords due to different hydrographical conditions. Tests of Ammonia beccarii found in the Gelting Bay, the Flensburg Fjord, showed traces of dissolution and development of double tests. Such specific abnormal tests mirror the peculiar environmental setting characterized by changes in salinity and enhanced sediment redeposition. It is concluded that abnormal tests as an indicator of environmental pollution have to be used cautiously in areas with strong environmental instability

Gauge fixing in (2+1)-gravity with vanishing cosmological constant

We apply Dirac's gauge fixing procedure to (2+1)-gravity with vanishing cosmological constant. For general gauge fixing conditions based on two point particles, this yields explicit expressions for the Dirac bracket. We explain how gauge fixing is related to the introduction of an observer into the theory and show that the Dirac bracket is determined by a classical dynamical r-matrix. Its two dynamical variables correspond to the mass and spin of a cone that describes the residual degrees of freedom of the spacetime. We show that different gauge fixing conditions and different choices of observers are related by dynamical Poincar\'e transformations. This allows us to locally classify all Dirac brackets resulting from the gauge fixing and to relate them to a set of particularly simple solutions associated with the centre-of-mass frame of the spacetime.Comment: Talk given at the Workshop on Noncommutative Field Theory and Gravity Corfu, September 7 - 11, 2011; 20 pages, 6 figure

Pressure dependence and non-universal effects of microscopic couplings on the spin-Peierls transition in CuGeO_3

The theory by Cross and Fisher (CF) is by now commonly accepted for the description of the spin-Peierls transition within an adiabatic approach. The dimerization susceptibility as the essential quantity, however, is approximated by means of a continuum description. Several important experimental observations can not be understood within this scope. Using density matrix renormalization group (DMRG) techniques we are able to treat the spin system exactly up to numerical inaccuracies. Thus we find the correct dependence of the equation of state on the spin-spin interaction constant J, still in an adiabatic approach. We focus on the pressure dependence of the critical temperature which is absent in the CF theory as the only energy scale with considerable pressure dependence is J which drops out completely. Comparing the theoretical findings to the experimentally measured pressure dependence of the spin-Peierls temperature we obtain information on the variation of the frustration parameter with pressure. Furthermore, the ratio of the spectral gap and the transition temperature is analyzed.Comment: 5 pages, 5 figures and 1 table include

3. Wochenbericht M78/1

Können schmelzende Gletscher und heftige Niederschläge in Europa den Golfstrom schwächen? Dieser Frage wollen Kieler Meereswissenschaftler auf der METEOR-Expedition M 78/1 zur Wiege von „Europas Fernheizung“ in der Karibik nachgehen. Die Expedition beginnt am 21. Februar 2009 im Hafen von Colon (Panama) und endet am 28. März 2009 im Hafen von Port of Spain (Trinidad and Tobago). Die Fahrtroute führt zunächst nach Norden in den Golf von Mexiko, an der Nordküste von Kuba entlang und zwischen Kuba und Haiti hindurch wieder nach Süden bis vor das Mündungsdelta des Orinoko. Dabei legt die METEOR unter der wissenschaftlichen Fahrtleitung von Dr. Joachim Schönfeld (IFM-GEOMAR) rund 5200 Seemeilen zurück. FS Meteor Reise M78/1 (Colon, Panama – Port of Spain, Trinidad) 3. Wochenbericht, 2. bis 8. März 200

5. Wochenbericht M78/1

Können schmelzende Gletscher und heftige Niederschläge in Europa den Golfstrom schwächen? Dieser Frage wollen Kieler Meereswissenschaftler auf der METEOR-Expedition M 78/1 zur Wiege von „Europas Fernheizung“ in der Karibik nachgehen. Die Expedition beginnt am 21. Februar 2009 im Hafen von Colon (Panama) und endet am 28. März 2009 im Hafen von Port of Spain (Trinidad and Tobago). Die Fahrtroute führt zunächst nach Norden in den Golf von Mexiko, an der Nordküste von Kuba entlang und zwischen Kuba und Haiti hindurch wieder nach Süden bis vor das Mündungsdelta des Orinoko. Dabei legt die METEOR unter der wissenschaftlichen Fahrtleitung von Dr. Joachim Schönfeld (IFM-GEOMAR) rund 5200 Seemeilen zurück. FS Meteor Reise M78/1 (Colon, Panama – Port of Spain, Trinidad) 5. Wochenbericht, 16. bis 22. März 200

Monitoring benthic foraminiferal dynamics at Bottsand coastal lagoon (western Baltic Sea)

Benthic foraminifera from Bottsand coastal lagoon, western Baltic Sea, have been studied since the mid-1960s. They were monitored annually in late autumn since 2003 at the terminal ditch of the lagoon. There were 12 different species recognised, of which three have not been recorded during earlier investigations. Dominant species showed strong interannual fluctuations and a steady increase in population densities over the last decade. Elphidium incertum, a stenohaline species of the Baltic deep water fauna, colonised the Bottsand lagoon in 2016, most likely during a period of salinities >19 units and water temperatures of 18 °C on average in early autumn. The high salinities probably triggered their germination from a propagule bank in the ditch bottom sediment. The new E. incertum population showed densities higher by an order of magnitude than those of the indigenous species. The latter did not decline, revealing that E. incertum used another food source or occupied a different microhabitat. Elphidium incertum survived transient periods of lower salinities in late autumn 2017, though with reduced abundances, and became a regular faunal constituent at the Bottsand lagoon