The first lines of divergence in the Bacteria domain seem to be the hyperthermophilic organisms: a check using an outgroup of sequences from mesophiles in phylogenetic analysis

We have conducted a check by substituting, in a previous phylogenetic analysis, an outgroup of sequences from hyperthermophilic archaea with another of mesophilic sequences of archaea. This should remove a possible compositional bias which might be responsible for the deep position of Thermotogales and Aquificales in the Bacteria domain, as observed in previous analyses. This check brought to light a weak compositional bias which does not seem, however, to entirely explain the deep position occupied by hyperthermophilic bacteria. The present analysis also seems to show that Planctomycetes are one of the deepest lines of divergence in the Bacteria domain, although they do not seem to be the very deepest

Montmorillonite protection of an UV-irradiated hairpin ribozyme: evolution of the RNA world in a mineral environment

International audienceBACKGROUND: The hypothesis of an RNA-based origin of life, known as the "RNA world", is strongly affected by the hostile environmental conditions probably present in the early Earth. In particular, strong UV and X-ray radiations could have been a major obstacle to the formation and evolution of the first biomolecules. In 1951, J. D. Bernal first proposed that clay minerals could have served as the sites of accumulation and protection from degradation of the first biopolymers, providing the right physical setting for the evolution of more complex systems. Numerous subsequent experimental studies have reinforced this hypothesis. RESULTS: The ability of the possibly widespread prebiotic, clay mineral montmorillonite to protect the catalytic RNA molecule ADHR1 (Adenine Dependent Hairpin Ribozyme 1) from UV-induced damages was experimentally checked. In particular, the self-cleavage reaction of the ribozyme was evaluated after UV-irradiation of the molecule in the absence or presence of clay particles. Results obtained showed a three-fold retention of the self-cleavage activity of the montmorillonite-protected molecule, with respect to the same reaction performed by the ribozyme irradiated in the absence of the clay. CONCLUSION: These results provide a suggestion with which RNA, or RNA-like molecules, could have overcame the problem of protection from UV irradiation in the RNA world era, and suggest that a clay-rich environment could have favoured not only the formation of first genetic molecules, but also their evolution towards increasingly complex molecular organization

Carbonic anhydrase inhibitors. inhibition of cytosolic isozymes I and II and transmembrane, cancer-associated isozyme IX with anions.

Except for sulfonamides, metal complexing anions represent the second class of inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The first inhibition study of the transmembrane, tumor-associated isozyme CA IX with anions is reported here. Inhibition data of the cytosolic isozymes CA I and CA II with a large number of anionic species such as halides, pseudohalides, bicarbonate, nitrate, hydrosulfide, arsenate, etc., are also provided for comparison. Isozyme IX has an inhibition profile by anions different in some aspects from those of CA I and CA II, that may have interesting physiological consequences

Carbonic anhydrase inhibitors. Inhibition of cytosolic isozymes I and II and transmembrane, cancer-associated isozyme IX with lipophilic sulfonamides.

A series of new compounds was obtained by reaction of aromatic/heterocyclic sulfonamides incorporating amino groups with N,N-diphenylcarbamoyl chloride and diphenylacetyl chloride. These sulfonamides were assayed for the inhibition of three carbonic anhydrase (CA, EC 4.2.1.1) isozymes: the cytosolic CA I and CA II, and the transmembrane, cancer-associated isozyme CA IX. Good inhibitors against all these isoforms were detected, and the inhibition profile of the newly investigated isozyme IX was observed to be different from that of the cytosolic isozymes, I and II. This may lead to the development of novel anticancer therapies based on the selective inhibition of CA IX

The origin of life: chemical evolution of a metabolic system in a mineral honeycomb?

For the RNA-world hypothesis to be ecologically feasible, selection mechanisms acting on replicator communities need to be invoked and the corresponding scenarios of molecular evolution specified. Complementing our previous models of chemical evolution on mineral surfaces, in which selection was the consequence of the limited mobility of macromolecules attached to the surface, here we offer an alternative realization of prebiotic group-level selection: the physical encapsulation of local replicator communities into the pores of the mineral substrate. Based on cellular automaton simulations we argue that the effect of group selection in a mineral honeycomb could have been efficient enough to keep prebiotic ribozymes of different specificities and replication rates coexistent, and their metabolic cooperation protected from extensive molecular parasitism. We suggest that mutants of the mild parasites persistent in the metabolic system can acquire useful functions such as replicase activity or the production of membrane components, thus opening the way for the evolution of the first autonomous protocells on Earth

DNA as a possible target for antitumor Ruthenium(III) complexes.

8ARCH. BIOCHEM. BIOPHYS.ARCH. BIOCHEM. BIOPHYS.nonenoneGALLORI E.; VETTORI C.; ALESSIO E.; GONZALEZ-VILCHEZ F.; VILAPLANA R.; ORIOLI P.; CASINI A.; MESSORI L.Gallori, E.; Vettori, C.; Alessio, Enzo; GONZALEZ VILCHEZ, F.; Vilaplana, R.; Orioli, P.; Casini, A.; Messori, L

DNA as a possible target for antitumor ruthenium(111) complexes - A spectroscopic and molecular biology study of the interactions of two representative antineoplastic ruthenium(111) complexes with DNA

The interaction of two experimental ruthenium(III)-containing antitumor complexes—Na[trans-RuCl4(DMSO)(Im)] (NAMI) and dichloro(1,2-propylendiaminetetraacetate)ruthenium(III) (RAP)—with DNA was investigated through a number of spectroscopic and molecular biology techniques, including spectrophotometry, circular dichroism, gel shift analysis, and restriction enzyme inhibition. It was found that both complexes slightly alter DNA conformation, modify its electrophoretic mobility, and inhibit DNA recognition and cleavage by some restriction enzymes, though they were less effective than cisplatin in producing such effects. Notably, the effects produced by NAMI on DNA were much larger than those induced by RAP. Implications of these results for the mechanism of action of ruthenium(III) antitumor complexes are discussed

Role of clays in protecting adsorbed DNA against X-ray radiation

The X-ray emission of the young Sun was much harder and intense than today and might have played a significant role in the evolution of complex organics in protoplanetary environments. We investigate the effects of soft X-rays on tryptophan molecules in aqueous solutions at room temperature. As results of the irradiation experiments we detect several light species indicative of fragmentation, together with large molecular structures such as tryptophan dipeptide and tripeptide. Complexification is more evident in H2O solution than in D2O, probably due to isotopic effects. The abundances of peptides depend on the irradiation dose and decrease with increasing energy deposition. Radicals such as D, OD, H and OH, induced by the X-ray interaction with solvents, play a major role in determining the final products