a b s t r a c tThe dipeptide seryl-histidine (Ser-His) catalyses the condensation of esters of amino acids, peptide fragments, and peptide nucleic acid (PNA) building blocks, bringing to the formation of peptide bonds. Di-, tri-or tetra-peptides can be formed with yields that vary from 0.5% to 60% depending on the nature of the substrate and on the conditions. Other simpler peptides as Gly-Gly, or Gly-Gly-Gly are also effective, although less efficiently. We discuss the results from the viewpoint of primitive chemistry and the origin of long macromolecules by stepwise fragment condensations.

In this work we provide evidence for the potential presence of a potassium channel in skeletal muscle mitochondria. In isolated rat skeletal muscle mitochondria, Ca(2+) was able to depolarize the mitochondrial inner membrane and stimulate respiration in a strictly potassium-dependent manner. These potassium-specific effects of Ca(2+) were completely abolished by 200 nM charybdotoxin or 50 nM iberiotoxin, which are well-known inhibitors of large conductance, calcium-activated potassium channels (BK(Ca) channel). Furthermore, NS1619, a BK(Ca)-channel opener, mimicked the potassium-specific effects of calcium on respiration and mitochondrial membrane potential. In agreement with these functional data, light and electron microscopy, planar lipid bilayer reconstruction and immunological studies identified the BK(Ca) channel to be preferentially located in the inner mitochondrial membrane of rat skeletal muscle fibers. We propose that activation of mitochondrial K(+) transport by opening of the BK(Ca) channel may be important for myoprotection since the channel opener NS1619 protected the myoblast cell line C2C12 against oxidative injury.

Although gradual deterioration of life functions with age is not a fundamental rule, it is pervasive among living organisms, regardless of their mode of reproduction and the number of constituent cells. However, deterioration can be temporarily arrested or slowed down due to the process of anhydrobiosis. Two modes of anhydrobiosis can be distinguished for the developmental and adult stages of animals. Developmental resting stages are reported for different animals, including sponges (Porifera), stingers (Cnidaria), flatworms (Platyhelminthes), insects (Insecta), copepods (Copepoda) and branchiopods (Branchiopoda). However, anhydrobiosis occurring at any stage of animal life, including adults, is found only in a few invertebrate phyla, namely roundworms (Nematoda), wheel animals (Rotifera) and water bears (Tardigrada). Notably, in the second group anhydrobiosis has been proposed to eliminate or slow‐down aging symptoms. This, in turn, may correlate with higher fitness and fecundity, and increased offspring longevity. We present available data concerning anhydrobiosis of tardigrades, bdelloid rotifers and nematodes, the only animals known to be capable of anhydrobiosis as adult individuals. The impact of anhydrobiosis on animal aging is illustrated by two models based on experimental data, namely the “Sleeping Beauty” and “Picture of Dorian Grey” models. According to the “Sleeping Beauty” model, anhydrobiotic organisms do not age during anhydrobiosis, whereas the “Picture of Dorian Grey” model predicts that the anhydrobiotic organism ages, at least during the initial stage of anhydrobiosis. Finally, we discuss possible implications of these models for individual longevity and survival as well as phenotypic diversity of taxa and their evolution. A better understanding of life strategies of anhydrobiotic animals both at the ontogenetic and phylogenetic levels can provide answers to many fundamental questions and useful practical outputs in branches of applied sciences.

A new scenario for prebiotic formation of nucleic acid oligomers is presented. Peptide catalysis is applied to achieve condensation of activated RNA monomers into short RNA chains. As catalysts, L-dipeptides containing a histidine residue, primarily Ser-His, were used. Reactions were carried out in self-organised environment, a water-ice eutectic phase, with low concentrations of reactants. Incubation periods up to 30 days resulted in the formation of short oligomers of RNA. During the oligomerisation, an active intermediate (dipeptide-mononucleotide) is produced, which is the reactive species. Details of the mechanism and kinetics, which were elucidated with a set of control experiments, further establish that the imidazole side chain of a histidine at the carboxyl end of the dipeptide plays a crucial role in the catalysis. These results suggest that this oligomerisation catalysis occurs by a transamination mechanism. Because peptides are much more likely products of spontaneous condensation than nucleotide chains, their potential as catalysts for the formation of RNA is interesting from the origin-of-life perspective. Finally, the formation of the dipeptide-mononucleotide intermediate and its significance for catalysis might also be viewed as the tell-tale signs of a new example of organocatalysis.