The caudal regeneration blastema is an accumulation of rapidly proliferating stem cells in the flatworm Macrostomum lignano

Background: Macrostomum lignano is a small free-living flatworm capable of regenerating all body parts posterior of the pharynx and anterior to the brain. We quantified the cellular composition of the caudal-most body region, the tail plate, and investigated regeneration of the tail plate in vivo and in semithin sections labeled with bromodeoxyuridine, a marker for stem cells (neoblasts) in S-phase. Results: The tail plate accomodates the male genital apparatus and consists of about 3,100 cells, about half of which are epidermal cells. A distinct regeneration blastema, characterized by a local accumulation of rapidly proliferating neoblasts and consisting of about 420 cells (excluding epidermal cells), was formed 24 hours after amputation. Differentiated cells in the blastema were observed two days after amputation (with about 920 blastema cells), while the male genital apparatus required four to five days for full differentiation. At all time points, mitoses were found within the blastema. At the place of organ differentiation, neoblasts did not replicate or divide. After three days, the blastema was made of about 1420 cells and gradually transformed into organ primordia, while the proliferation rate decreased. The cell number of the tail plate, including about 960 epidermal cells, was restored to 75% at this time point. Conclusion: Regeneration after artificial amputation of the tail plate of adult specimens of Macrostomum lignano involves wound healing and the formation of a regeneration blastema. Neoblasts undergo extensive proliferation within the blastema. Proliferation patterns of S-phase neoblasts indicate that neoblasts are either determined to follow a specific cell fate not before, but after going through S-phase, or that they can be redetermined after S-phase. In pulse-chase experiments, dispersed distribution of label suggests that S-phase labeled progenitor cells of the male genital apparatus undergo further proliferation before differentiation, in contrast to progenitor cells of epidermal cells. Mitotic activity and proliferation within the blastema is a feature of M. lignano shared with many other regenerating animals

A silicified Early Triassic marine assemblage from Svalbard

peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=tjsp2

The impact of corporate volunteering on CSR image: a consumer perspective

Received: 29 June 2013 / Accepted: 15 January 2014Abstract Corporate volunteering (CV) is known to be an effective employee engagement initiative. However, despite the prominence of corporate social responsibility (CSR) in academia and practice, research is yet to investigate whether and how CV may influence consumer perceptions of CSR image and subsequent consumer behaviour. Data collected using an online survey in Australia show perceived familiarity with a company’s CV programme to positively impact CSR image and firm image, partially mediated by others-centred attributions. CSR image, in turn, strengthens affective and cognitive loyalty as well as word-of-mouth. Further analysis reveals the moderating effect of perceived leveraging of the corporate volunteering programme, customer status and the value individuals place on CSR. The paper concludes with theoretical and managerial implications, as well as an agenda for future research.Carolin Plewa, Jodie Conduit, Pascale G. Quester, Claire Johnso

Systems perspective on partnership governance in smallholder agricultural value chains

Smallholder farmers face numerous challenges when participating in and upgrading their position in value chains. The amount of resources that farmers have, also referred to as their asset base, is important when creating and sustaining competitive value chains. Unfortunately, smallholders often face constraints in some or all of the human, social, financial, natural, and institutional assets that are needed in order to succeed (Lie et al. 2012). From a systems perspective, these limits on the farm asset base have important feedback effects that compound market access constraints over time and reduce the ability of policy-makers and donors to successfully intervene in pro-poor value chains. The smallholder dairy goat farmers of Twawose association in Mgeta, Tanzania exemplify this problem (Lie et al. 2012). While collectively, and with strategic public sector support, they have managed to improve their asset base enough to collect and process goat milk into drinking yogurt for sale at the local market. However, this group has not yet managed to penetrate larger urban markets, which limits the potential of small dairy farmers to develop

Dr. H.G. Bronn\u27s Klassen und Ordnungen des Thier-Reichs, wissenschaftlich dargestellt in Wort und Bild.

Bd.1:Abt.1-2 (1880-1887) [Lacks:pg.LXXXV