The cytoplasm of an Acetabularia cell is normally at a potential of about -170 mv relative to the external solution; the vacuole is also at this potential. Although there is strict flux equilibrium for all ions, the potential is more negative than the Nernst potentials of any of the permeating ions. Darkness, CCCP, low temperature, and reducing [Cl(-)](o) by a factor of 25 all rapidly depolariz...

Planarians are bilaterally symmetrical fresh water organisms capable of regenerating body parts from small fragments following bodily injury. Planarians possess a specialized population of pluripotent cells called neoblasts, which are responsible for their unique regenerative ability. The study of planarian stem cell biology and regeneration has traditionally focused on the transcription factor...

Planaria possess a population of pluripotent adult stem cells called neoblasts, capable of differentiating into all cell types required to regenerate entire animals from almost any fragment. The regeneration of different fragments is catalogued in a body of classical experiments by many eminent scientists. Here, we endeavour to explore these classical observations and insights and combine them ...

Melanins are ubiquitous and biologically important pigments, yet the molecular mechanisms that regulate their synthesis and biochemical composition are not fully understood. Here we present a study that supports a role for serotonin in melanin synthesis in the planarian Schmidtea mediterranea. We characterize the tryptophan hydroxylase (tph) gene, which encodes the rate-limiting enzyme in serot...

The EGFR pathway is an essential signaling system in animals, whose core components are the epidermal growth factors (EGF ligands) and their trans-membrane tyrosine kinase receptors (EGFRs). Despite extensive knowledge in classical model organisms, little is known of the composition and function of the EGFR pathway in most animal lineages. Here, we have performed an extensive search for the pre...

The problem of regeneration is fundamentally a problem of tissue homeostasis involving the replacement of cells lost to normal 'wear and tear' (cell turnover), and/or injury. This attribute is of particular significance to organisms possessing relatively long lifespans, as maintenance of all body parts and their functional integration is essential for their survival. Because tissue replacement ...

The complex Cladonia mediterranea belongs to the section Impexae and is formed by C. azorica, C. macaronesica and C.mediterranea. These species are basically distributed in the Mediterranean and Macaronesian Regions. In the present work the limits between the species of this complex are re-examined. To this end, the morphological characters were studied along with the secondary metabolites and ...

a EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK b Association EURATOM-ENEA-CREATE, DIMET Univ. Mediterranea di Reggio Calabria Via Graziella, Loc. Feo di Vito, I-89060 Reggio Calabria, Italy c EURATOM-ENEA Consorzio RFX, C.so Stati Uniti 4, I-35127 Padova, Italy d University of Padova, Department of Management and Engineering, Stradella San Nicola 3, I-361...

The asexual freshwater planarian is a constitutive adult, whose central nervous system (CNS) is in a state of constant homeostatic neurogenesis. However, very little is known about the extrinsic signals that act on planarian stem cells to modulate rates of neurogenesis. We have identified two planarian homeobox transcription factors, Smed-nkx2.1 and Smed-arx, which are required for the maintena...

Planaria possess a population of pluripotent adult stem cells called neoblasts, capable of differentiating into all cell types required to regenerate entire animals from almost any fragment. The regeneration of different fragments is catalogued in a body of classical experiments by many eminent scientists. Here, we endeavour to explore these classical observations and insights and combine them ...