Fragments from Graeco-Jewish writers

collected and ed. with brief introd. and notes by Wallace Nelson Stearns

Judaica seu veterum scriptorum profanorum de rebus Judaicis fragments

coll. Fr. Carolus Meier

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules (1). Here we present evidence that tRFs from the archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii (2). The Val-tRF is processed in a stress- dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-bound non-protein-coding RNA (ncRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production (1). (1) Gebetsberger J. and Polacek N. (2013), RNA Biol. 10:1798-1808 (2) Gebetsberger J. et. al. (2012), Archaea, Article ID 260909

A Hebrew Deluge story in cuneiform : and other epic fragments in the Pierpont Morgan Library

by Albert T. Clay

Fragments from the Cairo Genizah in the Freer Collection

ed. by Richard Gottheil ...

Le savoir des religions. Fragments d’historiographie religieuse

L’histoire des religions ne saurait se passer d’une réflexion préalable sur ses propres conditions d’élaboration. Qu’est-ce qu’un « savoir religieux », qu’est-ce qu’un savoir « sur le religieux », en quoi et comment se distinguent-ils l’un de l’autre ? Ce livre est issu d’une série de recherches et d’enquêtes portant sur des horizons historiques et culturels contrastés. Il montre comment un scribe mésopotamien, un philosophe grec, un clerc bouddhiste, un égyptologue contemporain, un historien des religions, etc, élaborent leurs savoirs, comment ces savoirs se transforment et se perpétuent, quelles fonctions ils remplissent, qui les met en oeuvre, où et comment ils s’enracinent, pourquoi ils meurent.

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress- dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-bound non-protein-coding RNA (ncRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [1].

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress- dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-associated non-protein-coding RNA (rancRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [3].

tRNA-derived fragments target the small ribosomal subunit to fine-tune translation

Post-transcriptional cleavage of RNA molecules to generate smaller fragments is a widespread mechanism that enlarges the structural and functional complexity of cellular RNomes. In particular, fragments deriving from both precursor and mature tRNAs represent one of the rapidly growing classes of post-transcriptional RNA pieces. Importantly, these tRNA-derived fragments (tRFs) possess distinct expression patterns, abundance, cellular localizations, or biological roles compared with their parental tRNA molecules [1]. Here we present evidence that tRFs from the halophilic archaeon Haloferax volcanii directly bind to ribosomes. In a previous genomic screen for ribosome-associated small RNAs we have identified a 26 residue long fragment originating from the 5’ part of valine tRNA (Val-tRF) to be by far the most abundant tRF in H. volcanii [2]. The Val-tRF is processed in a stress-dependent manner and was found to primarily target the small ribosomal subunit in vitro and in vivo. Translational activity was markedly reduced in the presence of Val-tRF, while control RNA fragments of similar length did not show inhibition of protein biosynthesis. Crosslinking experiments and subsequent primer extension analyses revealed the Val-tRF interaction site to surround the mRNA path in the 30S subunit. In support of this, binding experiments demonstrated that Val-tRF does compete with mRNAs for ribosome binding. Therefore this tRF represents a ribosome-associated non-coding RNA (rancRNA) capable of regulating gene expression in H. volcanii under environmental stress conditions probably by fine-tuning the rate of protein production [3].

An Avron rule for fragments of R-mingle

Axiomatic bases of admissible rules are obtained for fragments of the substructural logic R-mingle. In particular, it is shown that a ‘modus-ponens-like’ rule introduced by Arnon Avron forms a basis for the admissible rules of its implication and implication–fusion fragments, while a basis for the admissible rules of the full multiplicative fragment requires an additional countably infinite set of rules. Indeed, this latter case provides an example of a three-valued logic with a finitely axiomatizable consequence relation that has no finite basis for its admissible rules.

Selective sampling during catastrophic disruption: Mapping the location of reaccumulated fragments in the original parent body

In this paper, we simulate numerically the catastrophic disruption of a large asteroid as a result of a collision with a smaller projectile and the subsequent reaccumulation of fragments as a result of their mutual gravitational attractions. We then investigate the original location within the parent body of the small pieces that eventually reaccumulate to form the largest offspring of the disruption as a function of the internal structure of the parent body. We consider four cases that may represent the internal structure of such a body (whose diameter is fixed at 250 km) in various early stages of the Solar System evolution: fully molten, half molten (i.e., a 26 km-deep outer layer of melt containing half of the mass), solid except a thin molten layer (8 km thick) centered at 10 km depth, and fully solid. The solid material has properties of basalt. We then focus on the three largest offspring that have enough reaccumulated pieces to consider. Our results indicate that the particles that eventually reaccumulate to form the largest reaccumulated bodies retain a memory of their original locations in the parent body. Most particles in each reaccumulated body are clustered from the same original region, even if their reaccumulations take place far away. The extent of the original region varies considerably depending on the internal structure of the parent. It seems to shrink with the solidity of the body. The fraction of particles coming from a given depth is computed for the four cases, which can give constraints on the internal structure of parent bodies of some meteorites. As one example, we consider the ureilites, which in some petrogenetic models are inferred to have formed at particular depths within their parent body. (C) 2014 Elsevier Ltd. All rights reserved.