Effect of thiostrepton and 3′-terminal fragments of aminoacyl-tRNA on EF-Tu and ribosome-dependent GTP hydrolysis

The effect of the antibiotics thiostrepton and micrococcin on EF-T_u-catalyzed (ribosome-dependent) GTP hydrolysis in the presence of A-Phe, C-A-Phe, or C-C-A-Phe (related to the sequence of the 3′-terminus of aminoacyl-tRNA)(System I) or by methanol (‘uncoupled GTPase’, System II) was investigated. In System I, thiostrepton increases the binding affinities of the effectors to the EF-T_u·GTP·70 S ribosome complex, as well as the extent of the GTP hydrolysis, while the K^GTP_m is virtually unchanged. Similarly, in the uncoupled system (System II) and in the absence of effectors, thiostrepton significantly increases V^GTP_max, whereas K^GTP_m remains unaffected. Micrococcin is without any effect in both systems. The ‘uncoupled GTPase’ (in System II) is also strongly inhibited by C-A-Phe. The results indicate the crucial role of the EF-T_u site which binds the aminoacylated C-C-A terminus of aminoacyl-tRNA in promoting GTP hydrolysis. It follows that the binding of the model effectors (such as C-C-A-Phe) to that site is favorably influenced by the interaction of thiostrepton with the 50 S ribosomal subunit, whereas thiostrepton, per se, does not influence the affinity of EF-T_u for GTP.     

Complex patterns of grooming and sexual activity in Barbary macaques (Macaca sylvanus)

Grooming in primates is often considered a “currency” that can be exchanged for other “services” or “commodities” such as reciprocal grooming, coalitionary support, infant handling, tolerance around food sources, active food sharing, or mating opportunities. Previous studies on primate grooming‐for‐sex exchange viewed the males as the demanding class, with the females as suppliers of mating opportunities. In this study, we examine the broader context of grooming‐for‐mating exchange in Barbary macaques in Gibraltar. Our data show that Barbary macaque males groom females with whom they are mating more frequently and for longer periods than other females, and the relationship between grooming and mating remains significant in both sexual and nonsexual contexts. In addition, females groomed males with whom they were mating more frequently and for longer periods than other males. In both sexes, grooming was observed to be far more frequent and to occur for longer durations in sexual compared to nonsexual contexts. We did not find any difference in grooming behavior between presexual and postsexual contexts. Our data suggest that there is no simple model to describe Barbary macaque grooming patterns in sexual contexts. Although our results are partly consistent with male use of grooming as payment for mating, broadly assessed grooming‐mating patterns cannot be solely explained by a male‐driven grooming‐for‐mating exchange.     

A new mite species of the genus <Emphasis Type="Italic">Lasioseius</Emphasis> (Acari: Gamasina: Ascidae) from central Europe

Lasioseius minor sp. n. (Acari: Gamasina: Ascidae) is described from the soil of thermophilic oak forest from south-western Slovakia. L. minor sp. n. belongs to the subgenus Crinidens having not reduced number of dorsal setae, separate metapodal platelets, epistomal margin with three well developed branches and only two small smooth pointed dorsal setae.     

Biochemical characteristics of the Ca2+ pumping ATPase in the peribacteroid membrane from broad bean root nodules

Ca²⁺-ATPase in the peribacteroid membrane (PBM) of symbiosomes isolated from Vicia faba root nodules was characterized in terms of its hydrolytic and transport activities. Both activities were found to be pH-dependent and exhibit pH optimum at pH 7.0. Translocation of Ca²⁺ through the PBM by the Ca²⁺-ATPase was shown to be fueled by ATP and other nucleotide triphosphates in the following order: ATP?>?ITP???GTP???UTP???CTP, the K _m of the enzyme for MgATP being about 100 μM. Ca-dependent ITP-hydrolytic activity of symbiosomes was investigated in the presence of the Ca-EGTA buffer system and showed the affinity of PBM Ca²⁺-ATPase for Ca²⁺ of about 0.1 μM. The transport activity of Ca²⁺-ATPase was inhibited by erythrosin B as well as orthovanadate, but markedly stimulated by calmodulin from bovine brain. These results allowed us to conclude that this enzyme belongs to IIB-type Ca²⁺-ATPases which are present in other plant membranes.     

Towards resolving conservation issues through historical aerial imagery: vegetation cover changes in the Central European tundra

Mountain ecosystems are considered to be sensitive to global change and human disturbance. Our retrospective analysis of archival aerial imagery showed dynamics of arctic-alpine tundra vegetation in the Krkono?e Mountains, Czech Republic; image classification revealed a change in land cover classes in 44% of the study area over the past eighty years. This particular ecosystem holds many rare features, such as high numbers of endemic, glacial relict and rare species as well as relict geomorphological components such as sorted patterned ground. Our study revealed an accelerating expansion of the native and planted shrub, Pinus mugo, from 30.6% of the study area in 1936 to 48.6% in 2018, mostly at the expense of grasslands that decreased from 59.3% in 1936 to 44.2% in 2018. Shrub expansion represents a threat to relict periglacial landforms, covering 8% of the sorted patterned ground in 1936 and 26.5% in 2018. Shrub encroachment was shown to be due to artificial planting of the pine in the past as well as the cessation of former farming (mowing and cattle grazing) and, most probably, also by global change. Both dwarf pine stands and tundra grasslands hold high conservation value (Natura 2000 habitats); a balance between different nature protection interests must, therefore, be ensured. Detailed spatio-temporally, explicit outputs of the remote sensing analysis can serve as a baseline for nature conservation in order to prepare corresponding management plans.

     

General Synthesis of 2′(3′)-O-Aminoacyl Oligoribonucleotides Related to the 3′-Terminus of aa-tRNA

Abstract

A general method is presented for the synthesis of the title compounds using phosphotriester methodology and employing a unique combination of protecting groups, including the double protection of the guanosine aglycon.     

Revisiting Street Intersections Using Slot-Based Systems

Since their appearance at the end of the 19th century, traffic lights have been the primary mode of granting access to road intersections. Today, this centuries-old technology is challenged by advances in intelligent transportation, which are opening the way to new solutions built upon slot-based systems similar to those commonly used in aerial traffic: what we call Slot-based Intersections (SIs). Despite simulation-based evidence of the potential benefits of SIs, a comprehensive, analytical framework to compare their relative performance with traffic lights is still lacking. Here, we develop such a framework. We approach the problem in a novel way, by generalizing classical queuing theory. Having defined safety conditions, we characterize capacity and delay of SIs. In the 2-road crossing configuration, we provide a capacity-optimal SI management system. For arbitrary intersection configurations, near-optimal solutions are developed. Results theoretically show that transitioning from a traffic light system to SI has the potential of doubling capacity and significantly reducing delays. This suggests a reduction of non-linear dynamics induced by intersection bottlenecks, with positive impact on the road network. Such findings can provide transportation engineers and planners with crucial insights as they prepare to manage the transition towards a more intelligent transportation infrastructure in cities.