Michael Kuhlmann

G-CSF/SCF reduces inducible arrhythmias in the infarcted heart potentially via increased connexin43 expression and arteriogenesis

Granulocyte colony-stimulating factor (G-CSF), alone or in combination with stem cell factor (SCF), can improve hemodynamic cardiac function after myocardial infarction. Apart from impairing the pump function, myocardial infarction causes an enhanced vulnerability to ventricular arrhythmias. Therefore, we investigated the electrophysiological effects of G-CSF/SCF and the underlying cellular events in a murine infarction model. G-CSF/SCF improved cardiac output after myocardial infarction. Although G-CSF/SCF led to a twofold increased, potentially proarrhythmic homing of bone marrow (BM)-derived cells to the area of infarction, <1% of these cells adopted a cardial phenotype. Inducibility of ventricular tachycardias during programmed stimulation was reduced 5 wk after G-CSF/SCF treatment. G-CSF/SCF increased cardiomyocyte diameter, arteriogenesis, and expression of connexin43 in the border zone of the infarction. An enhanced expression of the G-CSF receptor demonstrated in cardiomyocytes and other cell types of the infarcted myocardium indicates a sensitization of the heart to direct influences of this cytokine. In addition to paracrine effects potentially caused by the increased homing of BM-derived cells, these might contribute to the therapeutic effects of G-CSF.

Conservation ecology of bees: populations, species and communities

Recent concerns regarding the decline of plant and pollinator species, and the impact on ecosystem functioning, has focused attention on the local and global threats to bee diversity. As evidence for bee declines is now accumulating from over broad taxonomic and geographic scales, we review the role of ecology in bee conservation at the levels of species, populations and communities. Bee populations and communities are typified by considerable spatiotemporal variation; whereby autecological traits, population size and growth rate, and plant-pollinator network architecture all play a role in their vulnerability to extinction. As contemporary insect conservation management is broadly based on species- and habitattargeted approaches, ecological data will be central to integrating management strategies into a broader, landscape scale of dynamic, interconnected habitats capable of delivering bee conservation in the context of global environmental change.ZusammenfassungDie meisten der bereits ausgestorbenen oder vom Aussterben bedrohten Arten sind Insekten. Nichtsdestotrotz ist der Schutz von Insekten bisher weitgehend vernachlässigt worden. Die Befürchtungen jedoch, dass Pflanzen und ihre Bestäuber Rückgänge verzeichnen und dementsprechend Ökosystemfunktionen negativ beeinflussen können, hat letztendlich die lokalen und globalen Bedrohungen der Bienendiversität ins Schlaglicht gerückt. Anzeichen für den Rückgang von Bienen häufen sich sowohl in taxonomischer als auch in geographischer Hinsicht. Wir geben hier eine Übersicht über die Rolle ökologischer Faktoren im Bienenschutz, wobei wir besonders die Frage der Arten, Populationen und Artgemeinschaften beleuchten.Erfolreicher Artenschutz erfordert zunächst ein grundlegendes Verständnis von zwischenartlichen Wechselwirkungen und von autökologischen Merkmalen (Abb. 1 und Tab. I). Das Aussterben von Bienenarten ist in vielen Fällen nicht dokumentiert und demzufolge sind vergleichende Analysen wichtig, um autökologische Faktoren erkennen zu können, die mit der Anfälligkeit zum Artenrückgang verknüpft sein können. Bienenpopulationen und Bienengemeinschaften zeichnen sich durch erhebliche raumzeitliche Schwankungen hinsichtlich ihrer Häufigkeit und Zusammensetzung aus, so dass die Variabilität dieser ökologischen Daten dazu führen kann, dass lange Beobachtungszeiträme notwendig sind, um faktische Rückgange sichtbar machen zu können. Im Idealfall würde die Bestimmung kritischer Werte der Populationsgrössen und des Populationswachstums experimentelle Ansätze erfordern. In der Praxis werden aufgrund der logistischen Anforderungen, dem Problem fehlender Wiederholungen und den räumlichen Grössenordnungen jedoch meist Modellansätze bevorzugt, um Populationsrückgänge und Antworten auf regelnde Massnahmen sichtbar zu machen. Wir diskutieren hier die Erfassung von drei Schlüsselparametern für die Abschätzung von Populationsgrössen und Wachstumsraten: Ausbreitungsrate, Paarungssystem, sowie Prädatoren, Parasiten und Pathogene. Die Antwort von Einzeltieren, Populationen und Artgemeinschaften von Bienen auf anthropogen bedingte Umweltveränderungen ist primär bedingt durch die räumliche und zeitliche Verteilung von floralen sowie Nist- und Überwinterungsresourcen, die jeweils in Beziehung stehen zum Sammelverhalten und der Ausbreitungsfähigkeit der Bienen. Obwohl die primären Faktoren, die die Verteilung dieser Resourcen bestimmen, bekannt sind, nämlich Habitatverlust, bzw. Fragmentierung, ergeben empirische Daten bezüglich der Antwort der Bienengemeinschaften auf diese Faktoren kein einheitliches Bild (Tab. II). Netzwerktheoretische Ansätzen in Untersuchungen zur Architektur von Pflanzen/Bestäuber Netzwerken lassen jetzt Fortschritte erkennen und haben unsere Fähigkeit verbessert, Interaktionen zwischen Arten auf der Ebene von Gemeinschaften definieren und vorhersehen zu können. Mit Blick auf die globalen Umweltveränderungen wird die akkurate Abschätzung der Zahl, Stärke, Symmetrie und Variabilität dieser Interaktionen und ihr Einfluss auf die Toleranz von Bienengemeinschaften gegen das Aussterben zunehmend an Bedeutung gewinnen. Da gegenwärtige Artenschutzmassnahmen im wesentlichen den Schutz von einzelnen Arten oder von Habitaten im Blick haben, werden ökologische Daten entscheidend sein für die Integration dieser beiden Managementstrategien auf einer breiteren, landschaftsorientierten Ebene von dynamischen und untereinander verbundenden Habitaten, die dann dazu beitragen können, dass Bienenschutz im Kontext globaler Umweltveränderungen möglich wird.

Decreasing Abundance, Increasing Diversity and Changing Structure of the Wild Bee Community (Hymenoptera: Anthophila) along an Urbanization Gradient

Background Wild bees are important pollinators that have declined in diversity and abundance during the last decades. Habitat destruction and fragmentation associated with urbanization are reported as part of the main causes of this decline. Urbanization involves dramatic changes of the landscape, increasing the proportion of impervious surface while decreasing that of green areas. Few studies have investigated the effects of urbanization on bee communities. We assessed changes in the abundance, species richness, and composition of wild bee community along an urbanization gradient. Methodology/Principal Findings Over two years and on a monthly basis, bees were sampled with colored pan traps and insect nets at 24 sites located along an urbanization gradient. Landscape structure within three different radii was measured at each study site. We captured 291 wild bee species. The abundance of wild bees was negatively correlated with the proportion of impervious surface, while species richness reached a maximum at an intermediate (50%) proportion of impervious surface. The structure of the community changed along the urbanization gradient with more parasitic species in sites with an intermediate proportion of impervious surface. There were also greater numbers of cavity-nesting species and long-tongued species in sites with intermediate or higher proportion of impervious surface. However, urbanization had no effect on the occurrence of species depending on their social behavior or body size. Conclusions/Significance We found nearly a third of the wild bee fauna known from France in our study sites. Indeed, urban areas supported a diverse bee community, but sites with an intermediate level of urbanization were the most speciose ones, including greater proportion of parasitic species. The presence of a diverse array of bee species even in the most urbanized area makes these pollinators worthy of being a flagship group to raise the awareness of urban citizens about biodiversity.

The taxonomist - an endangered race. A practical proposal for its survival.

BackgroundTaxonomy or biological systematics is the basic scientific discipline of biology, postulating hypotheses of identity and relationships, on which all other natural sciences dealing with organisms relies. However, the scientific contributions of taxonomists have been largely neglected when using species names in scientific publications by not citing the authority on which they are based.DiscussionConsequences of this neglect is reduced recognition of the importance of taxonomy, which in turn results in diminished funding, lower interest from journals in publishing taxonomic research, and a reduced number of young scientists entering the field. This has lead to the so-called taxonomic impediment at a time when biodiversity studies are of critical importance.Here we emphasize a practical and obvious solution to this dilemma. We propose that whenever a species name is used, the author(s) of the species hypothesis be included and the original literature source cited, including taxonomic revisions and identification literature - nothing more than what is done for every other hypothesis or assumption included in a scientific publication. In addition, we postulate that journals primarily publishing taxonomic studies should be indexed in ISISM.SummaryThe proposal outlined above would make visible the true contribution of taxonomists within the scientific community, and would provide a more accurate assessment for funding agencies impact and importance of taxonomy, and help in the recruitment of young scientists into the field, thus helping to alleviate the taxonomic impediment. In addition, it would also make much of the biological literature more robust by reducing or alleviating taxonomic uncertainty.

Granulocyte Colony-Stimulating Factor (G-CSF) for Cardio- and Cerebrovascular Regenerative Applications

The cytokine granulocyte colony-stimulating factor (G-CSF) is produced by numerous cell types including immune and endothelial cells. G-CSF binding to its receptor G-CSF-R which belongs to the cytokine receptor type I family depends on the interaction of alpha-helical motifs of the former and two fibronectin type III as well as an immunoglobulin-like domain of the latter. It activates several signalling transduction pathways including PI3K/Akt, Jak/Stat and MAP kinase, thereby promoting survival, proliferation, differentiation and mobilisation of haematopoietic stem and progenitor cells. Accordingly, recombinant human (rh)G-CSF has been extensively used in clinical haematology and oncology to enable bone marrow transplantation or to treat chemotherapy-associated neutropenia. Using animal models it has been recently shown that G-CSF, alone or in combination with other cytokines such as stem cell factor (SCF), causes an accumulation of bone marrow-derived cells in the infarcted heart which, however, do not differentiate into cardiac cells. Nevertheless, since beneficial effects on structural and functional properties were observed in animal models of cardiac, brain and hindlimb ischaemia other mechanisms of G-CSF action must be operative. Recent evidence suggests paracrine effects mediated by the immigrated bone marrow-derived cells and/or direct effects of the cytokine on resident G-CSF-R expressing cells. In both cases these may include promotion of cellular survival, proliferation and differentiation. First clinical studies in patients with myocardial infarction, heart failure and stroke have been accomplished and are reviewed in this paper.

Ecological networks are more sensitive to plant than to animal extinction under climate change

Impacts of climate change on individual species are increasingly well documented, but we lack understanding of how these effects propagate through ecological communities. Here we combine species distribution models with ecological network analyses to test potential impacts of climate change on >700 plant and animal species in pollination and seed-dispersal networks from central Europe. We discover that animal species that interact with a low diversity of plant species have narrow climatic niches and are most vulnerable to climate change. In contrast, biotic specialization of plants is not related to climatic niche breadth and vulnerability. A simulation model incorporating different scenarios of species coextinction and capacities for partner switches shows that projected plant extinctions under climate change are more likely to trigger animal coextinctions than vice versa. This result demonstrates that impacts of climate change on biodiversity can be amplified via extinction cascades from plants to animals in ecological networks.

Paclitaxel Delivered to Adventitia Attenuates Neointima Formation without Compromising Re-Endothelialization after Angioplasty in a Porcine Restenosis Model

Purpose: To investigate the effect of paclitaxel delivered into the adventitia of pig femoral arteries on neointima formation and hyperplasia as well as re-endothelialization. Methods: Paclitaxel or vehicle was delivered into the adventitia of pig femoral arteries using a needle injection catheter following balloon overstretch. Arteries were then serially examined by angiography, Evans blue staining, morphometry, and immunohistochemistry for up to 12 weeks. Results: Local adventitial delivery of paclitaxel significantly attenuated neointima formation. The area of neointima (0.41±0.17 versus 2.75±0.81 mm2, p<0.01), the ratio of intima to media (0.12±0.05 versus 0.86±0.35, p<0.05), and the degree of stenosis (12.80%±3.13% versus 47.06%±7.25%, p<0.01) were significantly lower in the paclitaxel-treated group compared to controls. Furthermore, cell proliferation was significantly diminished following adventitial delivery of paclitaxel from day 3 to 21 compared to controls. Complete reendothelialization was observed 3 weeks after intervention in both groups of arteries treated with paclitaxel or vehicle alone. Conclusion: Paclitaxel delivered into the adventitia of pig femoral arteries effectively attenuates neointima formation after angioplasty without compromising re-endothelialization. Adventitial drug delivery may therefore be an alternative to drug-eluting stents for the prevention of restenosis.

Diversity, Distribution Patterns and Endemism of Southern African Bees (Hymenoptera: Apoidea)

An analysis of southern African bee diversity patterns based on 420 species reveals a bipolar pattern with highest species diversity located in the arid west of South Africa and the relatively moist east of the country. A detailed investigation of the distributions of 59 Colletes species shows a congruence of distribution areas of most species with seasonality of precipitation, a pattern that can be assumed for the majority of bee species. A total of 32 (sub)genera with about 256 species is strictly endemic to southern Africa with an exceptionally high number of endemic species (95%) strictly confined to the winter rainfall area.

Synchrony of pollinators and plants in the winter rainfall area of South Africa—observations from a drought year

The arid winter rainfall area of South Africa is a centre of bee diversity and endemism. Host plant synchrony is hypothesized as one possible mechanism for an elevated rate of speciation in desert bees, where rainfall is considered to initiate for the emergence especially of oligolectic (pollen specialist) bees. In Namaqualand in 2003, a drought year, the absence of early precipitation postponed the main flowering season by five weeks to early/mid September. Despite the lack of rain and flowers bee activity was already very high in August as recorded with colour trapping. Five highly specialised species of Rediviva (Melittidae) as well as many other bee species had emerged before the flowering season had started. The majority of bees were probably not nesting as none of the collected individuals carried pollen. Therefore failure in reproduction can be assumed. These observations show that bees in Namaqualand are not synchronised with their host plants and that rainfall might not be an abiotic cue for their emergence which contradicts current hypotheses. Usually, precipitation as well as flowering season in Namaqualand is fairly predictable. Thus it seems that evolutionary processes did not lead to adaptation of (oligolectic) bees to their host plants as one would expect in a xeric environment.

Molecular phylogeny and historical biogeography of the bee genus Colletes Latreille, 1802 (Hymenoptera: Apiformes: Colletidae), based on mitochondrial COI and nuclear 28S sequence data

A phylogenetic analysis of the intrageneric relationships within the bee genus Colletes using a combined data set of the mitochondrial cytochrome oxidase 1 (COI) and 28S sequences is presented and its implications for historical biogeography are investigated. We analyzed 91 out of 469 described Colletes species (19.4%) from the entire range of distribution and 25 outgroup taxa representing all colletid subfamilies closely related to Colletinae. Eight different combinations of alignment parameters were used for the 28S data, and our combined data set comprised between 1801 and 1845 aligned nucleotides with COI contributing 339 informative bases and 28S between 318 and 360 informative sites. Our results corroborate the monophyly of about half of the Old World subgenera and show the need for a taxonomic re-delimitation of other groups currently accepted. The phylogenetic results confirm the South American origin of Colletes and multiple faunal exchange events between North America and Eurasia. The last continent colonized was Africa south of the Sahara, which experienced at least two independent invasions.