The last-born daughter cell contributes to division orientation of Drosophila larval neuroblasts

The highly proliferative neuroblasts of the Drosophila larval brain divide over many cell cycles in a polarized manner. Here the authors show that the orientation of the axis of NB divisions is defined by the position of their last-born daughter cell

Notch Signaling:Where Is the Action?

It has been a long-standing question as to whether the activation of Notch by its ligands occurs in a specific region of the plasma membrane. A study now shows that this is indeed the case in the Drosophila sensory organ precursor cell lineage

Ökologisch fairer Welthandel: zum Spannungsfeld von Handel, Umwelt und Entwicklung

Im ausgehenden 20. Jahrhundert nimmt das Phänomen der "Globalisierung" einen gravierenden Stellenwert im internationalen Wirtschaftsgeschehen und in der internationalen Politikdiskussion ein. Das fortschreitende Zusammenwachsen der Volkswirtschaften macht es immer schwieriger, die einzelnen Akteure im Wirtschaftsgeschehen zu kontrollieren und erfordert ein verstärktes Zusammenarbeiten in internationalen Partnerschaften, um den Veränderungen des weltwirtschaftlichen Umfeldes in bezug auf Handel, Finanzströme und auch die globale Umwelt zu begegnen. In der öffentlichen Diskussion und zwischen Ökonomen, Ökologen und Politikern ist unstrittig, daß im neuen Jahrtausend eine Reihe von besonderen Problemstellungen gelöst werden muß, die u.a. in engem Zusammenhang mit der Globalisierung stehen. So weist das World Watch Institute in seinem zu Beginn des Jahres 2000 veröffentlichten Bericht zum Zustand der Weltumwelt auf alarmierende Veränderungen des Weltklimas, der Weltmeere und der Artenvielfalt hin, die für Industrie- und gerade auch für Entwicklungsländer von schwerwiegender Bedeutung sind. Beispielsweise gefährdet die Erhöhung des Meeresspiegels infolge der Klimaerwärmung aufgrund der zunehmenden Urbanisierung und Industrialisierung die niedriggelegenen und vielbevölkerten Regionen in Bangladesh, wodurch ökologische, ökonomische und soziale Konsequenzen zu erwarten sind. Maßnahmen zur Lösung gerade auch globaler Umweltprobleme können entwicklungs- und handelshemmend sein und so auf Interessenkonflikte zwischen Industrie- und Entwicklungsländern treffen. Die vorliegende Arbeit befaßt sich daher mit der Frage, wie der internationale Welthandel unter Berücksichtigung der Umwelt aussehen könnte, ohne daß eine Benachteiligung der Entwicklungsländer erfolgt. Der im folgenden zugrunde liegende Referenzrahmen soll damit ein ökologisch „fairer“ Welthandel sein, dersich an der effizienten Allokation der Umwelt orientiert, ohne den Freihandel alsZiel vollkommen abzulehnen. Eine Sonderbehandlung der Entwicklungsländer,die auch eine Abweichung von der allokativen Effizienz bedeuten kann, ist gegebenenfalls bei einem Vergleich mit den Industrieländern zu rechtfertigen

Politisch relevanter Totenkult

In Germany a new cult of the dead soldier is emerging. Whoever thinks this cult is only an antiquated custom of military rituals, which should be done away with, or whoever declares this cult to be an object of political discussion of only secondary rank, is missing one of the important political and sociological dimensions of the changing reproduction of the military in the time of the Afghanistan war. The article shows which necessary contribution this cult of the dead makes to Germany’s ability to wage war. Two important functions of this cult can be made out: to maintain the soldiers’ motivation, and the population’s acceptance of dead soldiers due to the war. The article focuses on the second function

Morphological effects on colonization and succession of aquatic and riparian organism groups

The European Water Framework Directive (2000/60/EC) claims a good ecological status of all ground and surface waters in the European Union according to chemical, hydromorphological and biological conditions. Unfortunately, rivers were strongly altered in the last centuries. Therefore, the number of restoration measures strongly increased in the last decade. Aquatic organism groups (e.g., benthic invertebrates and fish), which are used to assess the ecological status, show low or no responses to restoration, although a strong correlation of hydromorphological measures and biotic responses is expected. Some studies addressed the factor time as the major setback in the missing restoration effects. Currently, the knowledge on time spans required for successful recolonization of restored sections is poor. Effects of restoration measures on riparian organism groups are also less investigated, although single studies reveal strong responses to changing habitat conditions. Furthermore, studies which compare effects of restoration on both aquatic and riparian organism groups are missing. This thesis focused on hydromorphological river restoration measures in Germany and their effects on aquatic and riparian habitats and organism groups. The following questions were addressed: - How do riparian organism groups respond to hydromorphological restoration measures? - How do habitats and species assemblages of the river and the floodplain develop in the first years after restoration and over time? - How do aquatic and riparian organism groups differ in their responses to restoration measures? To answer the first question, the effects of hydromorphological restoration on riparian habitats and organism groups were analyzed by using the example of carabid beetles and floodplain vegetation in a dataset of 24 restoration measures. For the second and third question, aquatic and riparian habitats and species assemblages were investigated in two restored mid-sized mountain rivers at different time spans after restoration. Thus, pioneer colonization and successional processes were analyzed. Restoration effects differed between aquatic and riparian, but also between the individual organism groups. For these differences, the impact of multiple factors is suggested, e.g., the magnitude of habitat generation, dispersal abilities of organism groups, the presence of source populations and accessibility of restored sections for dispersing species. Morphological river restoration measures increased habitat diversity mainly in riparian areas with strong benefits for carabid beetles and floodplain vegetation. The strong responses of these species to habitat changes render them suitable indicators for morphological restoration measures. Missing or respectively minor responses of benthic invertebrates and fish reflected the minor enhancement of substrate diversity on the river bottom of restored sections combined with low dispersal ability and the lack of source populations in the direct surroundings. In contrast, aquatic macrophytes react fast and strong to restoration. For them, shallow bankside areas have a high importance as propagules can accumulate in these areas resulting in fast colonization of restored sections subject to the condition that source population upstream from restored sections are present. The results of this thesis highlight the decisive role of the factor time for the colonization of restored sections. Differing dispersal abilities of organism groups result in different time spans required for colonization of newly created habitats. Organism groups with high dispersal ability, e.g., riparian carabid beetles, are direct colonizers. In contrast, aquatic organism groups which have a lower dispersal ability and are currently suffering from multiple pressures need more time to reach restored sections. A high distance to source populations and deficits in longitudinal connectivity might retard or inhibit colonization of restored sections. In case of mountain rivers, the frequency and intensity of high discharges is another important factor influencing the development of habitats and colonization patterns of restored sections over time

Centrosomes remember which way is up

Microtubule-based memory helps orient dividing brain stem cells

The European HIV/AIDS archive : building a queer counter-memory

Mobilising a queer theoretical framework, by which we mean embracing unhappiness, ephemerality and instability, this chapter reflects on processes of archiving oral histories as part of the European HIV/AIDS Archive (EHAA) by presenting selected challenges and tensions that lie at the heart of remembering, narrating and archiving the HIV/AIDS epidemic in the broader European region. The EHAA, an online collection of oral history interviews and digitized materials, has been developed to further establish HIV/AIDS history as part of the broader social memory so as to work through the trauma of mass death and social discrimination, and to document innovations, tensions and inconsistencies in engaging with the epidemic across the region. Building on a growing interest in archiving histories of HIV activism from across Europe and North America, the EHAA project dates back to efforts by the "AIDS History into Museums Working Group" (AKAIM) to preserve such histories in Germany. The project was further developed and expanded in two research projects: ‘Disentangling European HIV/AIDS Policies: Activism, Citizenship and Health’ (EUROPACH) and ‘Don’t criminalize passion! The AIDS crisis and political mobilization in the 1980s and early 1990s in Germany’. Explicitly deviating from an investment in offspring as route for the transmission of memory, the EHAA joins other queer archival work imagined as sites for handing down queer history. The chapter hence argues that the EHAA contributes to queer memory work as a necessary revision of public remembrance and current perceptions of the epidemic, and, at the same time, as a source of inspiration for future activism

Stem cell decisions:A twist of fate or a niche market?

AbstractEstablishing and maintaining cell fate in the right place at the right time is a key requirement for normal tissue maintenance. Stem cells are at the core of this process. Understanding how stem cells balance self-renewal and production of differentiating cells is key for understanding the defects that underpin many diseases. Both, external cues from the environment and cell intrinsic mechanisms can control the outcome of stem cell division. The role of the orientation of stem cell division has emerged as an important mechanism for specifying cell fate decisions. Although, the alignment of cell divisions can dependent on spatial cues from the environment, maintaining stemness is not always linked to positioning of stem cells in a particular microenvironment or `niche'. Alternate mechanisms that could contribute to cellular memory include differential segregation of centrosomes in asymmetrically dividing cells