Lack of the murine homeobox gene Hesx1 leads to a posterior transformation of the anterior forebrain

The homeobox gene Hesx1 is an essential repressor that is required within the anterior neural plate for normal forebrain development in mouse and humans. Combining genetic cell labelling and marker analyses, we demonstrate that the absence of Hesx1 leads to a posterior transformation of the anterior forebrain (AFB) during mouse development. Our data suggest that the mechanism underlying this transformation is the ectopic activation of Wnt/beta-catenin signalling within the Hesx1 expression domain in the AFB. When ectopically expressed in the developing mouse embryo, Hesx1 alone cannot alter the normal fate of posterior neural tissue. However, conditional expression of Hesx1 within the AFB can rescue the forebrain defects observed in the Hesx1 mutants. The results presented here provide new insights into the function of Hesx1 in forebrain formation.     

Maintenance of previously uncultured freshwater archaea from anoxic waters under laboratory conditions

Culture conditions for the maintenance of previously uncultured members of the Archaea thriving in anoxic water layers of stratified freshwater lakes are described. The proposed enrichment conditions, based on the use of defined medium composition and the maintenance of anoxia, have been proven effective for the maintenance of the archaeal community with virtually no changes over time for periods up to 6 months as revealed by a PCR-DGGE analysis. Phylotypes belonging to groups poorly represented in culture collections such as the Deep-Sea Hydrothermal Vent Euryarchaeota (DHVE) and the Miscellaneous Crenarchaeotic Group (MCG) were maintained and selectively enriched when compared to the correspondent indigenous planktonic archaeal community.     

A CHARACEAN THALLUS WITH ATTACHED GYROGONITES AND ASSOCIATED FOSSIL CHAROPHYTES FROM THE MAASTRICHTIAN OF THE EASTERN PYRENEES (CATALONIA,SPAIN)1

The new species Clavatoraxis microcharophorus is described from the Lower Maastrichtian of the Eastern Pyrenees (Catalonia, Spain). Microchara sp. gyrogonites were found in anatomical connection with this thallus, attached to bract‐cell rosettes and coated by a structural tunica, formed by an expanded bract cell. This is a feature unknown in extant characeans, which only display lime incrustations similar to tunicae in extremely alkaline and well‐illuminated environments. This is the first time that a complete fossil characean is described. The attribution of characean vegetative remains to the genus Clavatoraxis shows that this genus is not exclusive of clavatoraceans as previously thought. The taphonomic study of C. microcharophorus sp. nov. and associated fossil charophytes, along with sedimentological and microfacies analyses, has enabled us to characterize the habitat of this species in the Maastrichtian lake of Vallcebre. They grew forming meadows, and their remains were deposited in the poorly oxygenated lake bottom, where they were well preserved. A number of other characeans and porocharaceans were living in shallower belts. This was the case for Peckichara sp. and Munieria grambasti in the freshwater lacustrine meadows. Another species, Feistiella malladae, was found parautochthonous in brackish lakes.     

Aequorin-expressing yeast emits light under electric control

In this study, we show the use of direct external electrical stimulation of a jellyfish luminescent calcium-activated protein, aequorin, expressed in a transgenic yeast strain. Yeast cultures were electrically stimulated through two electrodes coupled to a standard power generator. Even low (1.5 V) electric pulses triggered a rapid light peak and serial light pulses were obtained after electric pulses were applied periodically, suggesting that the system is re-enacted after a short refraction time. These results open up a new scenario, in the very interphase between synthetic biology and cybernetics, in which complex cellular behavior might be subjected to electrical control.     

The gift of motherhood: Egg donation in a Barcelona infertility clinic

In this paper we analyse the ways in which egg donors from a private infertility clinic in Barcelona try to render their new experience meaningful. Donors are striving to see their action as a contribution to the creation of a particular kinship bond – motherhood in another woman – by means of the abrogation of a bond that also looks very much like kinship, which links them to the individuals that will be born thanks to their eggs. The specific meaning that egg donation has for each donor varies according to her particular circumstances, but the language constructed in order to convey this meaning emerges from the creative expression of several cultural paradoxes and dichotomies that constitute, in themselves, an original and highly significant cultural grammar.     

Morphogenetic diversity of the ectomycorrhizal genus <Emphasis Type="Italic">Cortinarius</Emphasis> section <Emphasis Type="Italic">Calochroi</Emphasis> in the Iberian Peninsula

The taxonomic and genetic diversity of Cortinarius section Calochroi in one of the most biodiversity-rich regions in Europe, the Iberian Peninsula, was investigated through morphological and phylogenetic methods. This combined methodological approach allowed the identification of 15 known species and one new species, Cortinarius ortegae, which is described here. A dichotomous key is provided for field recognition of Calochroi species inhabiting different Iberian and Balearic Island woodlands. Polymorphism analyses within some studied species showed that the distribution of intraspecific lineages is dependent on geography and, in some cases, tree host. Furthermore, the dating analysis suggested that diversification within Calochroi started in the Pliocene and most of the current genetic diversity originated in the Pleistocene. This temporal scenario supports hypotheses in which climatic oscillations in the Quaternary may have been driving the evolution of this group of ectomycorrhizal fungi.     

Investigation of Bolivian plant extracts for their radical scavenging activity and antioxidant activity

Fifty-four different extracts of nine Bolivian plants belonging to the family Asteraceae were evaluated for their radical scavenging activity by the DPPH*, NBT/hypoxanthine superoxide, and (*)OH/luminol chemiluminescence methods, and for their antioxidant activity by the beta-carotene bleaching test. The total phenolic content was also determined by the Folin-Ciocalteu method, and the oxidative stability by the Rancimat test. Both remarkably high phenolic content and radical scavenging and antioxidant activities were found mainly in the ethyl acetate fractions among the different plant extracts. Some ethyl acetate and even some defatted crude extracts exhibited activities comparable to those of commercial extracts/compounds, thus making it possible to consider some of the studied plants as a potential source of antioxidants of natural origin.