Translational Elements Research Articles

EARLY STEPS IN THE FORMATION OF A TRANSLATION INITIATION COMPLEX ON NEWLY TRANSCRIBED MESSENGER RNA

ABSTRACT The aim of this study is to investigate how formation of a translation initiation complex affects the rate of transcription from a phage DNA template (λ plac or Ø 80 dlac DNA). Addition of "native" 30S ribosomes to a Ø 80 dlac in vitro transcription system (including limiting amounts of purified E. coli RNA polymerase and the requisite substrates) markedly enhances the rate of RNA synthesis. Factor free, 1 M NH4Cl washed 30S or 70S ribosomes show a weak albeit detectable activity, "run off 70S" or washed 50S being inefficient. Single addition of purified initiation factor IF3 greatly magnifies (about 2–3 fold) the stimulation obtained with washed 30S subunits, the effect being catalytic with respect to IF3; IF2 addition causes a weaker and stoichiometrical effect. Maximum stimulation (up to 6 fold) is achieved by the combined addition of washed ribosomes (30S or 70S), IF1, IF2, IF3 plus the highly purified fMet-tRNAfMet species. Under such conditions, very efficient initiator tRNA binding to nascent RNA does occur. Initiation factors show no activity in the absence of ribosomes. Kasugamycin greatly reduces the stimulation of RNA synthesis in the presence of the various translation elements. This system provides a new and very sensitive means to study the various factor dependent ribosome-messenger interactions even in the absence of initiator tRNA, thereby enabling one to analyze early translation initiation steps. Both the frequency of transcription initiation and the rate of RNA chain propagation appear to be enhanced when RNA synthesis and initiation of protein synthesis are coupled.

On the application of phase relationships to complex structures. IV. The coincidence method applied to general phases

For space groups with translational elements of symmetry it is possible to find relationships between the phases of pairs of reflexions which are of the same parity group. When the reflexions have one index in common then many indications for a given relationship may appear. A rigorous theory is described which enables the variance of the relationships to be derived although, in practice, a less rigorous approach is preferred which is more amenable to numerical work. The phase-coincidence procedure is being incorporated as an option in the MULTAN computer package for solving non-centrosymmetric structures.

Hadżi Dimityr Christo Botewa – obce elementy kulturowe w polskich przekładach

Hadzhi Dimitar by Hristo Botev – the foreign cultural elements in Polish translations
 The famous poetic work by Bulgarian artist Christo Botev – the romantic ballad Hadzhi Dimitar is full of foreign cultural elements that are recognized by Polish readers. This poem is an important center in the Bulgarian national discourse, inspired by southslavic folklore, strongly influenced by the hajduk‑legend, it mythologizes important Bulgarian historical event (the death of Hadzhi Dimitar and Stefan Karadzha on Mount Buzludzha). The analysis and interpretation of the original text and two polish translations by Z. Wolnikówna and W. Broniewski, allow to answer the following questions: if translators are intermediaries and interpreters of the elements of a foreign culture? Which strategies are used by translators to effective communication between the Bulgarian and Polish cultures? Do translations give a fair and accurate representation of the original poem?

Crystallographic groups in space and time: I. General definitions and basic properties

A generalization of the concept of n-dimensional magnetic group is considered which also admits discrete time translations. This leads to the study of crystallographic groups in n + 1-dimensional Euclidean, Minkowskian, Galilean and product spaces. Definitions are given for point groups, system groups, arithmetic and geometric crystal classes, Bravais classes, lattice systems and space(-time) groups in these spaces. As in the Euclidean case, space-time groups G n+1 appear in ( K, Z n+1 , φ)-extensions with K a crystallographic point group and φ a monomorphism φ: K → GL( n + 1, Z). As it is not yet known under which conditions groups appearing in such extensions may be interpreted as space-time groups, the classification of these groups is here restricted to the case of finite K. This classification arises by identifying space(-time) groups related by an isomorphism which takes into due account the various kinds of translation elements. For known geometric point groups a constructive method to derive all non-isomorphic space(-time) groups is given. The number of Bravais classes in Euclidean and Galilean space turns out to be finite. It is enumerably infinite in so-called product space and continuously infinite in Minkowskian space. The same is true for the number of non-isomorphic space(-time) groups.

Crossed-inverse and related loops

Introduction. Crossed-inverse (C.I.) loops are loops in which the identity xy x'=y holds for all x, y of the loop, x' being the right inverse of x. Such loops have already been studied [1; 2], and the results were useful in the study of neofields [6] and of geometrical subjects [3]. C.I. loops are special automorphic-inverse loops, that is, loops satisfying the identity (xy)'=x'y', for all x, y in the loop. The first section of this paper deals with isotopic C.I. loops, and they are proved to be also isomorphic. Then the autotopisms of C.I. loops are studied, and the main result of this part is the fact that the companions of all the autotopisms, i.e. the elements that correspond to the translation elements of the isotopisms, form a subloop which is commutative and Moufang. ?2 of the paper gives a necessary condition for the existence of finite automorphicinverse loops consisting only of the unit eleinent and inverse-cycles [cf. 1 ] of the same length. The condition concerning the equal length of all inversecycles is necessary for the transitivity of the automorphism group of the loop [2] and hence for the possibility of considering the loop as the additive loop of a neoring. The third part deals with a method of constructing infinite automorphic-inverse loops satisfying also certain other identities. The author is grateful to R. H. Bruck for fruitful discussions on the subject of this paper. 1. 1. Definitions. 1.11. The biunique mapping which maps every element, c, of a loop (G, *) on its right inverse will be called J. Thus c cJ= 1, and cJ-1 c= 1. In automorphic-inverse loops J is an automorphism. 1.12. In the principal isotope of the loop G, with the new operation (*) such that ag*fb =ab, for all a, b in G, the ordered pair (g, f) is called the pair of translation elements of the principal isotope. 1.2. Elementary properties of C.I. loops. 1.21. The identities ab aJ=b and a(b aJ) =b are equivalent. Proof. If P and Q are biunique mappings of the loop onto itself, then PQ= I, the identity mapping, if and only if QP=I. Let L(x) and R(x) be,