Polyoma Virus Mutants as Probes of Variety Among Mouse Embryonal Carcinoma Cell Lines

The tumor promoter 12–0-tetradecanoylphorbol-13-acetate (TPA) dramatically modifies the differentiative program of myotubes, developed in culture from chick embryo skeletal myogenic cells. In fact TPA selectively decreases the expression of differentiative parameters with a lag of 8–10 h from its administration to the cultures. We have tested whether the reported effect of TPA depends on the synthesis of specific products during the lag phase of TPA action. The data presented indicate that inhibition of protein synthesis by the use of cycloheximide prevents the appearance of TPA induced inhibition of the expression of differentiative products, such as creatine phosphokinase (CPK) activity and acetylcholine receptors (AChR). Following removal of cycloheximide and reinitiation of normal protein synthesis, the TPA induced inhibitory effect on CPK and AChR appears after a delay of about the same length as the time lag of TPA action. Our results indicate that inhibition of protein synthesis during the lag phase of TPA action prevents the effect of this tumor promoter on myotube differentiative parameters, and suggest that the expression of differentiative traits in cultured myotubes is affected by TPA via a regulatory step implying protein synthesis.     

Pronounced genetic diversity in tropical epiphyllous lichen fungi

Lowland tropical habitats harbour an unexplored genetic diversity of epiphyllous fungi. In the shade of rainforest understoreys, lichenized fungi are specialized to an ephemeral habitat where they produce little vegetative biomass and develop reproductive structures early. In a first population genetic study of epiphyllous lichen fungi, we analysed the intraspecific genetic diversity of five leaf-colonizing lichen mycobiont species. Sampling focused on a lowland perhumid forest plot in Costa Rica, with additional collections from other localities throughout the country. In all species we detected sympatric occurrence of highly diverged haplotypes. Haplotypes belonging to distinct clades in networks were also found on the same leaf, clearly indicating multiple independent colonization events on single leaves. Despite the unusually high genetic diversity of these leaf-colonizing tropical fungi, we did not detect pronounced spatial structure of the haplotype distribution between geographical regions. The observed patterns suggest that the diversity of foliicolous lichens could be much higher than expected, with several cryptic genetic lineages within each morphologically characterized species.     

Stone-curlews Burhinus oedicnemus and recreational disturbance: developing a management tool for access

Stone-curlews Burhinus oedicnemus have a vulnerable population status in the UK after a large population decline and range contraction since the 1930s. Much Stone-curlew breeding habitat is open-access land designated under the Countryside and Rights of Way Act 2000. In order to guide the conservation and habitat management for this species whilst allowing recreational access, a tool known as the Stone-Curlew Access Response Evaluator (SCARE) has been developed. SCARE offers a method to assess the effects of scenarios for future changes in disturbance type, routes and frequency and will be valuable in making informed decisions about the management of public access to Stone-curlew breeding sites and the deployment of habitat creation measures.