The alien flora of Greece: taxonomy,life traits and habitat preferences

The aim of the paper is the state-of-the-art assessment of the alien flora of Greece and its traits. The dataset consists of a total of 343 alien taxa, including 49 archaeophytes. The taxonomy, life traits and habitat of the 294 neophytes are analysed vs their naturalisation status. Out of the 122 (41%) naturalised neophytes, 50 are identified as exhibiting invasive behaviour. Poaceae, Asteraceae, Amaranthaceae, Solanaceae, Fabaceae, and Polygonaceae are the plant families richest in alien taxa. The majority of them are of American origin, followed by those of Asiatic and Mediterranean origin. The neophytes are predominantly herbs, most of them annuals. Yet, the perennial life cycle is equally frequent with the annual one and the proportion of phanerophytes in the alien flora is increased compared to the one of the native flora. Regarding flowering traits, most of the aliens have a long flowering period (over 1 month) and flower in late spring, summer and autumn, when few of the native plants are in bloom. Vertebrate zoochory and anemochory are the two dispersal modes mostly utilised by the alien plants (43 and 28%, respectively), while more than one dispersal mechanisms are functional for 56% of them. Artificial habitats have the highest frequencies of alien plants. The natural habitats with the highest numbers of aliens are the coastal ones and inland surface waters. Opuntia ficus-barbarica, Ailanthus altissima, Oxalis pes-caprae, Erigeron bonariensis, Amaranthus albus and Symphyotrichum squamatum are typical cases of plants characterised as invasive, having established in almost all the habitat groups identified. The diversity of the ecological characteristics of the plants suggests a potential of impacts that needs to be further assessed.     

A consultant's perspective on the regulatory hurdles to adaptive trials

This is a discussion of the following two papers appearing in this special issue on adaptive designs: 'A regulatory view on adaptive/flexible clinical trial design' by H. M. James Hung, Robert T. O'Neill, Sue-Jane Wang and John Lawrence and 'Confirmatory clinical trials with an adaptive design' by Armin Koch.     

Engineering the pH-dependence of kinetic parameters of maize glutathione S-transferase I by site-directed mutagenesis

The optimisation of enzymes for particular application or conditions remains an important target in all protein engineering endeavours. Here, we report a successful strategy for altering the pH-profile of kinetic parameters and to define in detail the molecular mechanism of maize glutathione S-transferase I (GST I). To accomplish this, selected residues from the glutathione binding site (His40, Ser11, Lys41, Asn49, Gln53 and Ser67) were mutated to Ala, and the pH-dependence of the catalytic parameters V(max), and V(max)/K(GSH)(m) of the mutated forms were analysed. The pH-dependence of V(max) for the wild-type enzyme exhibits two transitions in the acidic pH range with pK(a1) of 5.7 and pK(a2) of 6.6. Based on thermodynamic data, site-directed mutagenesis and UV deference spectroscopy, it was concluded that pK(a1) corresponds to GSH carboxylates, whereas the pK(a2) has a conformational origin of the protein. The pH-dependence of V(max)/K(GSH)(m) for the wild-type enzyme exhibits a single transition with pK(a) of 6.28 which was attributed to the thiol ionisation of bound GSH. These findings complement the conclusions about the catalytic mechanism deduced from the crystal structure of the enzyme and provide the basis for rationally designing engineered forms of GST I with valuable properties.     

Effects of physiological self-crowding of DNA on shape and biological properties of DNA molecules with various levels of supercoiling

DNA in bacterial chromosomes and bacterial plasmids is supercoiled. DNA supercoiling is essential for DNA replication and gene regulation. However, the density of supercoiling in vivo is circa twice smaller than in deproteinized DNA molecules isolated from bacteria. What are then the specific advantages of reduced supercoiling density that is maintained in vivo? Using Brownian dynamics simulations and atomic force microscopy we show here that thanks to physiological DNA–DNA crowding DNA molecules with reduced supercoiling density are still sufficiently supercoiled to stimulate interaction between cis-regulatory elements. On the other hand, weak supercoiling permits DNA molecules to modulate their overall shape in response to physiological changes in DNA crowding. This plasticity of DNA shapes may have regulatory role and be important for the postreplicative spontaneous segregation of bacterial chromosomes.     

Mammalian CORVET Is Required for Fusion and Conversion of Distinct Early Endosome Subpopulations

Early endosomes are organized in a network of vesicles shaped by cycles of fusion, fission, and conversion to late endosomes. In yeast, endosome fusion and conversion are regulated, among others, by CORVET, a hexameric protein complex. In the mammalian endocytic system, distinct subpopulations of early endosomes labelled by the Rab5 effectors APPL1 and EEA1 are present. Here, the function of mammalian CORVET with respect to these endosomal subpopulations was investigated. Tgfbrap1 as CORVET‐specific subunit and functional ortholog of Vps3p was identified, demonstrating that it is differentially distributed between APPL1 and EEA1 endosomes. Surprisingly, depletion of CORVET‐specific subunits caused fragmentation of APPL1‐positive endosomes but not EEA1 endosomes in vivo. These and in vitro data suggest that CORVET plays a role in endosome fusion independently of EEA1. Depletion of CORVET subunits caused accumulation of large EEA1 endosomes indicative of another role in the conversion of EEA1 endosomes into late endosomes. In addition, depletion of CORVET‐specific subunits caused alterations in transport depending on both the type of cargo and the specific endosomal subpopulation. These results demonstrate that CORVET plays distinct roles at multiple stages in the mammalian endocytic pathway.      

Narrow-Front Loop Migration in a Population of the Common Cuckoo Cuculus canorus,as Revealed by Satellite Telemetry

Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8), to wintering sites in south-western Central Africa (n = 6) and back to the breeding grounds (n = 3). Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival). Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.     

A non-innovator version of etanercept for treatment of arthritis

Etanercept is a soluble tumor necrosis factor (TNF) receptor originally approved for treatment of moderate-to-severe rheumatoid arthritis, juvenile rheumatoid arthritis, and psoriatic arthritis. We have developed a non-innovator version of the recombinant protein etanercept, with the investigational name AVG01 (trade name AVENT™), using a novel expression vector-based technology. Here we show, by extensive analytical characterization, that AVG01 is highly similar to the reference product Enbrel^® and demonstrates similar efficacy in pre-clinical studies.