The archaeal eIF2 homologue: functional properties of an ancient translation initiation factor

The eukaryotic translation initiation factor 2 (eIF2) is pivotal for delivery of the initiator tRNA (tRNAi) to the ribosome. Here, we report the functional characterization of the archaeal homologue, a/eIF2. We have cloned the genes encoding the three subunits of a/eIF2 from the thermophilic archaeon Sulfolobus solfataricus, and have assayed the activities of the purified recombinant proteins in vitro. We demonstrate that the trimeric factor reconstituted from the recombinant polypeptides has properties similar to those of its eukaryal homologue: it interacts with GTP and Met-tRNAi, and stimulates binding of the latter to the small ribosomal subunit. However, the archaeal protein differs in some functional aspects from its eukaryal counterpart. In contrast to eIF2, a/eIF2 has similar affinities for GDP and GTP, and the β-subunit does not contribute to tRNAi binding. The detailed analysis of the complete trimer and of its isolated subunits is discussed in light of the evolutionary history of the eIF2-like proteins

Mycotoxin mixtures in food and feed: holistic, innovative, flexible risk assessment modelling approach: MYCHIF

Mycotoxins are toxic compounds mainly produced by fungi of the genera Aspergillus, Penicillium and Fusarium. They are present, often as mixtures, in many feed and food commodities including cereals, fruits and vegetables. Their ubiquitous presence represents a major challenge to the health and well being of humans and animals. Hundreds of compounds are listed as possible mycotoxins occurring in raw and processed materials destined for human food and animal feed. In this study, mycotoxins of major toxicological relevance to humans and target animal species were investigated in a range of crops of interest (and their derived products). Extensive Literature Searches (ELSs) were undertaken for data collection on: (i) ecology and interaction with host plants of mycotoxin producing fungi, mycotoxin production, recent developments in mitigation actions of mycotoxins in crop chains (maize, small grains, rice, sorghum, grapes, spices and nuts), (ii) analytical methods for native, modified and co-occurring mycotoxins (iii) toxicity, toxicokinetics, toxicodynamics and biomarkers relevant to humans and animals (poultry, suidae (pig, wild boar), bovidae (sheep, goat, cow, buffalo), rodents (rats, mice) and others (horses, dogs), (iv) modelling approaches and key reference values for exposure, hazard and risk modelling. Comprehensive databases were created using EFSA templates and were stored in the MYCHIF platform. A range of approaches were implemented to explore the modelling of external and internal exposure as well as dose-response of mycotoxins in chicken and pigs. In vitro toxicokinetic and in vivo toxicity databases were exploited, both for single compounds and mixtures. However, large data gaps were identified particularly with regards to absence of common statistical and study designs within the literature and constitute an obstacle for the harmonisation of internal exposure and dose-response modelling. Finally, risk characterisation was also performed for humans as well as for two animal species (i.e. pigs and chicken) using available tools for the modelling of internal dose and a component-based approach for selected mycotoxins mixtures

Limnological studies on two acid sensitive lakes in the Central Alps (lakes Paione Superiore and Paione Inferiore, Italy)

A limnological study was performed during 1991 and 1992 on lakes Paione Superiore (LPS)and Paione Inferiore (LPI), located in the Ossola Valley, Central Alps. The two lakes are characterized by very low alkalinity values (LPI <3ueq l-1); notwithstanding the relatively low atmospheric acid load, diatom remains, carbonaceous particles and pigment profiles in the sediments all indicate that the two lakes have undergone acidification since the fifties. The biological communities (phyto-zooplankton and macrobenthic fauna) are simplified, in consequence of the extreme physical and chemical conditions. The biological characteristics of the two lakes are discussed in relation to the water chemistry and the presence or absence of stocked fis

Archaebacterial and eukaryotic ribosomal subunits can form active hybrid ribosomes

AbstractPurified ribosomal subunits from the extremely thermoacidophilic archaebacterium Sulfolobus solfataricus are able to recognize ribosomal subunits from the yeast Saccharomyces cerevisiae forming hybrid monosomes that can be revealed by sucrose gradient analysis and are active in peptide bond formation. Both reciprocal combinations (archaebacterial 30 S + eukaryotic 60S and archaebacterial 50 S + eukaryotic 40 S) are functional. In contrast, no hybrid couples are formed between subunits of yeast and Escherichia coli ribosomes. These results indicate that ribosomes of at least one archaebacterial species share specific structural features with those of the lower eukaryote S. cerevisiae