A. R. Luria and the Twin Method in Modern Medical Genetics

The twin method is one of the classical methods of medical genetics which aids in defining the role of factors of heredity and environment in traits of norm and pathology, to study development of multifactorial diseases and development of genetics of intellectual activity. From the genetic point of view twins may be either monozygotic or dizygotic. The field of intellectual activity, in particular learning ability, attention and memory is most difficult and inaccessible for the genetic analyses of twins. The very beginning of research of twins’ intellectual activity was laid by A.R. Luria in years 1920-1930 and the features of development of twins of various age wererevealed. Using tasks that required mental capacities of different levels: immediate memory vs cultural forms of mediated memory, Luria’s group compared results of monozygotic and dizygotic twins of different ages (5-7 and 11-13). It has been shown that monozygotic twins are much more similar between themselves concerningmental capacities, natural forms of memory than dizygotic twins. In the older group it was the same difference in natural forma, but much less difference between monozygotic and dizygotic tweens in culturally determined forms of memory. Much more similarity was observed between monozygotic twins who grew separately, thanbetween dizygotic, being raised in the identical social environment. During these researches a number of assumptions have been stated about « the influence of heredity on intellectual activity which will be revealed in the solution of tasks which don’t demand special knowledge». Prospects of modern researches are in comparison of concordance mono-and dizygotic twins, confirming A. R. Luria’s assumption of interrelation of natural memory and intellectual endowments of twins with their genotype. Medical genetics confirmsthat the extent of development of various intellectual traits of monozygotic and dizygotic twins is caused first of all by influence of the environment – training and experience which is revealed is increased in increased variability of most intellectual characteristics at the age of 14–16 years. Keywords: A.R.Luria, twin method, medical genetics, epigenetic changes

Roles of Titin in the Structure and Elasticity of the Sarcomere

The giant protein titin is thought to play major roles in the assembly and function of muscle sarcomeres. Structural details, such as widths of Z- and M-lines and periodicities in the thick filaments, correlate with the substructure in the respective regions of the titin molecule. Sarcomere rest length, its operating range of lengths, and passive elastic properties are also directly controlled by the properties of titin. Here we review some recent titin data and discuss its implications for sarcomere architecture and elasticity

Microrheology with Optical Tweezers of gel-like materials 'is not an option'!

Optical tweezers have been successfully adopted as exceptionally sensitive transducers for microrheology studies of complex 'fluids'. Despite the general trend, a similar approach cannot be adopted for microrheology studies of 'gel-like' materials, e.g. living cells.Comment: 3 pages, 1 figur

The role of biotechnology in the formation of scientific and technical progress

All of humanity is in a state of deep and irreversible civilization, the symptoms that are not only global economic problems but also an unprecedented decline in value consciousness. Intercivilizational conflicts are brewing. The greatest intercivilizational conflicts are brewing. The rules of exchange between economically strong and weak subjects are hopelessly outdated. Unfair mechanisms of exchange between economically strong and weak subjects are hopelessly outdated. An expanding Colonial politics is occurring in new, more complex forms on the planet. A “consumer society” as an alternative and non-alternative model of development seems unshakable. The idea of a “consumer” social system as the only non-alternative and progressive model of development seems unshakable. Which race will this run with the planet’s limited resources lead to? All people want to exchange spiritual wealth and freedom for material well-being

Titin isn't a sleeping giant

Photobleaching reveals that the backbone of muscle myofibrils is surprisingly mobile

Stretching Single Domain Proteins: Phase Diagram and Kinetics of Force-Induced Unfolding

Single molecule force spectroscopy reveals unfolding of domains in titin upon stretching. We provide a theoretical framework for these experiments by computing the phase diagrams for force-induced unfolding of single domain proteins using lattice models. The results show that two-state folders (at zero force) unravel cooperatively whereas stretching of non-two-state folders occurs through intermediates. The stretching rates of individual molecules show great variations reflecting the heterogeneity of force-induced unfolding pathways. The approach to the stretched state occurs in a step-wise "quantized" manner. Unfolding dynamics depends sensitively on topology. The unfolding rates increase exponentially with force f till an optimum value which is determined by the barrier to unfolding when f=0. A mapping of these results to proteins shows qualitative agreement with force-induced unfolding of Ig-like domains in titin. We show that single molecule force spectroscopy can be used to map the folding free energy landscape of proteins in the absence of denaturants.Comment: 12 pages, Latex, 6 ps figure

French-speaking teenagers’ mastery of connectives:: The role of vocabulary size and exposure to print

Connectives such as however and since play an important role for marking coherence relations in discourse and therefore are crucial for reading comprehension, which in turn is a strong predictor of academic success. Most research on the acquisition of connectives targeted younger children. Yet there is evidence that connective development extends well into adolescence and even adult speakers have difficulties with some coherence relations when they are conveyed by infrequent connectives bound to the written mode. In this paper, we tested the use of connectives encoding different coherence relations and bound to either the oral or the written modes. We studied the performance of native French-speaking teenagers (N = 154, Mage = 14.43, range: 12-19) in a cloze task and also assessed whether teenagers' vocabulary level and degree of exposure to print predicted the accuracy of connective use. Our findings show that the ability to use connectives appropriately increases with age. However, age played a lesser role compared to vocabulary knowledge and degree of exposure to print, thus indicating that lexicon size and reading habits are important factors explaining individual differences in the acquisition of connectives

Vocabulary size and exposure to print predict mastery of connectives in teenage years

Connectives such as because and but are crucial for signaling coherence relations in discourse. They contribute to a better reading comprehension and, thus, academic performance. The aim of this article is to contribute to our understanding of connective development during teenage years by studying individual differences in the performance of native Russian-speaking teenagers (N = 107, M age = 13.93, range: 11 to 17) in a connective-cloze task. The tested connectives marked six coherence relations and were used either predominantly in speech or in the written language. In addition, we examined whether students’ performance with the connectives was modulated by their general linguistic experience, as assessed by a vocabulary test and degree of exposure to print. Our results reveal that interpersonal differences in lexicon size and level of exposure to print were the strongest predictors of appropriate usage of connectives, whereas differences in age, connective mode, and polyfunctionality played a lesser role. This finding may indicate that, starting from age 11, biological age and intrinsic properties of connectives matter less for their mastery than general linguistic experience, as measured by vocabulary level and exposure to print

The 3-dimensional random walk with applications to overstretched DNA and the protein titin

We study the three-dimensional persistent random walk with drift. Then we develop a thermodynamic model that is based on this random walk without assuming the Boltzmann-Gibbs form for the equilibrium distribution. The simplicity of the model allows us to perform all calculations in closed form. We show that, despite its simplicity, the model can be used to describe different polymer stretching experiments. We study the reversible overstretching transition of DNA and the static force-extension relation of the protein titin.Comment: 9 pages, 10 figure