Effect of estradiol on aminoacid incorporation into proteins of different hypothalamic areas in prepuberal rats.

Estradiol in vitro produces a significant increase in the incorporation of 3H-leucine into proteins of the anterior hypothalamic area in prepuberal female rats, 15 and 20 days old, but not in younger animals. The ovarian hormone induced no changes in the protein synthetic activity of middle and posterior hypothalamus and cerebral cortex in prepuberal female rats of different ages. Estradiol did not modify the protein synthesis of the hypothalamus and cerebral cortex in prepuberal male rats.     

On the history of the isomorphism problem of dynamical systems with special regard to von Neumann’s contribution

This article reviews some major episodes in the history of the spatial isomorphism problem of dynamical systems theory (ergodic theory). In particular, by analysing, both systematically and in historical context, a hitherto unpublished letter written in 1941 by John von Neumann to Stanislaw Ulam, this article clarifies von Neumann’s contribution to discovering the relationship between spatial isomorphism and spectral isomorphism. The main message of the article is that von Neumann’s argument described in his letter to Ulam is the very first proof that spatial isomorphism and spectral isomorphism are not equivalent because spectral isomorphism is weaker than spatial isomorphism: von Neumann shows that spectrally isomorphic ergodic dynamical systems with mixed spectra need not be spatially isomorphic.     

The functional RNA domain 5BSL3.2 within the NS5B coding sequence influences hepatitis C virus IRES-mediated translation

Hepatitis C virus (HCV) translation is mediated by an internal ribosome entry site (IRES) located at the 5′ end of the genomic RNA. The 3′ untranslatable region (3′UTR) stimulates translation by the recruitment of protein factors that simultaneously bind to the 5′ end of the viral genome. This leads to the formation of a macromolecular complex with a closed loop conformation, similar to that described for the cap-translated mRNAs. We previously demonstrated the existence of a long-range RNA–RNA interaction involving subdomain IIId of the IRES region and the stem–loop 5BSL3.2 of the CRE element at the 3′ end of the viral genome. The present study provides evidence that the enhancement of HCV IRES-dependent translation mediated by the 3′UTR is negatively controlled by the CRE region in the human hepatoma cell lines Huh-7 and Hep-G2 in a time-dependent manner. Domain 5BSL3.2 is the major partner in this process. Mutations in this motif lead to an increase in IRES activity by up to eightfold. These data support the existence of a functional high order structure in the HCV genome that involves two evolutionarily conserved RNA elements, domain IIId in the IRES and stem–loop 5BSL3.2 in the CRE region. This interaction could have a role in the circularisation of the viral genome.     

Stanisław Staszic: An Early Surveyor of the Geology of Central and Eastern Europe

In the late eighteenth and early nineteenth centuries the Polish geoscientist, philosopher, and statesman Stanis?aw Staszic (1755–1826) conducted an extensive geological survey of Poland and adjacent areas. In 1815, he completed a book (in Polish), On the geology of the Carpathians and other mountains and lowlands of Poland, complemented by a well-made geological map of Central and Eastern Europe. Early in the nineteenth century, Staszic refined the idea of ‘geological mapping’, though initially he was interested in the exploration of mineral deposits, rock salt, copper and iron ores, and coal. Unlike his predecessors, his book adopted a temporal subdivision of rocks, using a somewhat modified version of Abraham Gottlob Werner's system. He delineated the surface distribution of five rock units and coloured them onto his map. His work gave expression to his view of geological history, and brought the ‘Enlightenment Period’ of geology in Central and Eastern Europe to a close.     

Scorpions are a food item of American black bears in Sonora, Mexico

The remains of the scorpion Diplocentrus peloncillensis Francke were found in 7 scats of black bears ( Ursus americanus ) collected in the Sierra de San Luis, Sonora, Mexico. The collection data and previously reported black bear population estimates for the study area suggested that, although scorpions are not a large part of black bear diets in Sonora, feeding on scorpions is not restricted to a single individual or family unit and is apparently a relatively common behavior in the population. Also, the discovery of D. peloncillensis in Sonora represents a new country record.     

The flight periodicity, attack patterns, and life history of Dryocoetes confusus Swaine (Coleoptera: Curculionidae: Scolytinae), the western balsam bark beetle, in north central Colorado

Dryocoetes confusus Swaine, the western balsam bark beetle, is an important bark beetle associated with Abies lasiocarpa (Hook.) Nutt. (subalpine fir) in western North America. Little information is available on the life cycle and ecology of this insect in Colorado. In this study in north central Colorado, we examined its flight periodicity, attack patterns, and life cycle in downed trees. Flight season, as indicated by pheromone-trap catches, began in early June. Peak flight was observed during early to mid-July. A second peak in flight was observed in some years, but its occurrence was not consistent. Preferred attack sites on downed trees were the underside or side of the log and through branch stubs. The life cycle for this beetle was completed in 2 years, consistent with earlier observations from British Columbia. Sex ratio was 1:1, but a higher percentage of males fly earlier in the season.