Leiomodin/tropomyosin interactions are isoform specific

Leiomodins are larger homologs of tropomodulin, a tropomyosin-binding, actin-capping protein. There are several leiomodin isoforms, one of them found in smooth muscles (Lmod1) and another one found in cardiac and skeletal muscles (Lmod2). In this work, the tropomyosin-binding abilities of these two isoforms were studied. The tropomyosin-binding sites were localized in the N-terminal regions of Lmod1 and Lmod2. The affinities of the leiomodin fragments containing the tropomyosin-binding sites for tropomyosin peptides containing N-termini of different tropomyosin isoforms, alpha, gamma and delta, were determined and compared using non-denaturing gel-electrophoresis and circular dichroism. It was shown that leiomodin/tropomyosin binding is isoform-specific and differs almost 100-fold for different tropomyosin isoforms.     

Structural and functional characteristics of the heart of professional soccer players after retirement from long-term sports activity

The structural and functional characteristics of the heart of 51 retired soccer players who ceased training 3–15 years ago are presented. A number of structural and functional signs of “athlete’s heart” detected in the subjects indicate more efficient heart functioning at rest and during exercise. The myocardium requires less oxygen per unit power of muscle work, and each gram of the myocardium of retired athletes performs more mechanical work than the myocardium of untrained subjects of the same age. This indicates long-term adaptation of the heart of retired athletes to muscle work. The heart functioning at rest and during exercise in retired athletes becomes less efficient with age, this trend being more pronounced in older former athletes than in younger ones. This is expressed in an increased oxygen consumption by the myocardium, a higher occurrence of atypical electrocardiogram patterns, age-related changes in myocardial contractility, and a decreased capacity of each gram of the myocardium for generating mechanical work.     

Ant semiochemicals limit apterous aphid dispersal

Some organisms can manipulate the nervous systems of others or alter their physiology in order to obtain benefit. Ants are known to limit alate aphid dispersal by physically removing wings and also through chemical manipulation of the alate developmental pathway. This results in reduced dispersal and higher local densities of aphids, which benefit ants in terms of increased honeydew and prey availability. Here, we show that the walking movement of mutualistic apterous aphids is also reduced by ant semiochemicals. Aphids walk slower and their dispersal from an unsuitable patch is hampered by ants. If aphid walking dispersal has evolved as a means of natural enemy escape, then ant chemicals may act as a signal indicating protection; hence, reduced dispersal could be adaptive for aphids. If, however, dispersal is primarily a means to reduce competition or to maintain persistent metapopulations, then manipulation by ants could be detrimental. Such manipulation strategies, common in host-parasite and predator-prey interactions, may be more common in mutualism than expected.     

Rapidly inducible, genetically targeted inactivation of neural and synaptic activity in vivo

Inducible and reversible perturbation of the activity of selected neurons in vivo is critical to understanding the dynamics of brain circuits. Several genetically encoded systems for rapid inducible neuronal silencing have been developed in the past few years offering an arsenal of tools for in vivo experiments. Some systems are based on ion-channels or pumps, others on G protein coupled receptors, and yet others on modified presynaptic proteins. Inducers range from light to small molecules to peptides. This diversity results in differences in the various parameters that may determine the applicability of each tool to a particular biological question. Although further development would be beneficial, the current silencing tool kit already provides the ability to make specific perturbations of circuit function in behaving animals.     

The effect of changes in CYP2E1 activity in the liver on toxicity and carcinogenicity of diethylnitrosamine in mice

In this work, the biological effects of diethylnitrosamine (DENA) have been studied under controlled conditions of its metabolism in mice of different ages. The results indicate that the general toxic and hepatocarcinogenic effects of DENA are mostly due to the parent compound, whereas the alkylating metabolites cause hepatic cell damage. Our findings cast doubt on the conventional understanding of the exclusive role of mutagenic activation in the carcinogenic action of chemicals.     

The use of duplex-specific crab nuclease for rapid analysis of single-nucleotide polymorphisms and the detection of DNA targets in complex PCR products

A rapid method for single-nucleotide polymorphism analysis and the detection of target clones after cloning of complex PCR products based on the use of duplex-specific crab nuclease and a universal fluorescent probe has been developed. The method is an alternative to the labor-intensive procedures of clone screening employing radioactively labeled probes, gel-based restriction analysis, and costly sequencing. The efficiency of the novel method has been demonstrated in a range of model systems.