Naturally Occurring Isoleucyl-tRNA Synthetase without tRNA-dependent Pre-transfer Editing

Isoleucyl-tRNA synthetase (IleRS) is unusual among aminoacyl-tRNA synthetases in having a tRNA-dependent pre-transfer editing activity. Alongside the typical bacterial IleRS (such as Escherichia coli IleRS), some bacteria also have the enzymes (eukaryote-like) that cluster with eukaryotic IleRSs and exhibit low sensitivity to the antibiotic mupirocin. Our phylogenetic analysis suggests that the ileS1 and ileS2 genes of contemporary bacteria are the descendants of genes that might have arisen by an ancient duplication event before the separation of bacteria and archaea. We present the analysis of evolutionary constraints of the synthetic and editing reactions in eukaryotic/eukaryote-like IleRSs, which share a common origin but diverged through adaptation to different cell environments. The enzyme from the yeast cytosol exhibits tRNA-dependent pre-transfer editing analogous to E. coli IleRS. This argues for the presence of this proofreading in the common ancestor of both IleRS types and an ancient origin of the synthetic site-based quality control step. Yet surprisingly, the eukaryote-like enzyme from Streptomyces griseus IleRS lacks this capacity; at the same time, its synthetic site displays the 10(3)-fold drop in sensitivity to antibiotic mupirocin relative to the yeast enzyme. The discovery that pre-transfer editing is optional in IleRSs lends support to the notion that the conserved post-transfer editing domain is the main checkpoint in these enzymes. We substantiated this by showing that under error-prone conditions S. griseus IleRS is able to rescue the growth of an E. coli lacking functional IleRS, providing the first evidence that tRNA-dependent pre-transfer editing in IleRS is not essential for cell viability

Visual Climate Change Communication: From Iconography To Locally Framed 3D Visualization

Climate change is an urgent problem with implications registered not only globally, but also on national and local scales. It is a particularly challenging case of environmental communication because its main cause, greenhouse gas emissions, is invisible. The predominant approach of making climate change visible is the use of iconic, often affective, imagery. Literature on the iconography of climate change shows that global iconic motifs, such as polar bears, have contributed to a public perception of the problem as spatially and temporally remote. This paper proposes an alternative approach to global climate change icons by focusing on recognizable representations of local impacts within an interactive game environment. This approach was implemented and tested in a research project based on the municipality of Delta, British Columbia. A major outcome of the research is Future Delta, an interactive educational game featuring 3D visualizations and simulation tools for climate change adaptation and mitigation future scenarios. The empirical evaluation is based on quantitative pre/post-game play questionnaires with 18 students and 10 qualitative expert interviews. The findings support the assumption that interactive 3D imagery is effective in communicating climate change. The quantitative post-questionnaires particularly highlight a shift in support of more local responsibility

Sezonska dinamika primarne i sekundarne produkcije u šaranskim ribnjacima

Sezonska dinamika biomase i kvalitativnog sastava fitoplanktona, zooplanktona i makrozoobentosa je istraživana u odnosu na fizičke i hemijske faktore vodene sredine, međusobno kao i u odnosu na gajene ribe u tri zemljana bazena. Fitoplankton je imao veliki diverzitet vrsta, naročito jestivih, tokom prvog dela sezone. Kasnije, sa porastom temperature, ihtiomase, količine ekskreta riba, degradacijom nepojedene hrane kao i povremenim smanjenjem količine vode u jezerima, došlo je do promene u pravcu dominacije filamentoznih Cyanophyta. Zooplankton i makrozoobentos su tokom celog perioda istraživanja imali mali diverzitet vrsta. Sezonalna dinamika zooplanktona se karakterisala dominacijom dve Rotatoria, Brachionus angularis i Keratella tropica i malom Cladocera Bosmina longirostris u sva tri bazena. Makrozoobentos je imao malu gustinu i biomasu, a larvame Chironomidae su dominirale tokom cele sezone

Protein Level and Efficiency of Feed Mixture for Common Carp (Cyprinus Carpio)

The quality of fish feed and its nutritional value are important for fish production. From an economic point of view it is vital to ensure a cheaper final product while from the nutritional aspects it is essential to fulfill the requirements of fish. The aim of this study was to investigate the digestibility and effect of feed mixtures with different protein content on growth of carp fry. The experiment was carried out at the Laboratory for fish nutrition of the Faculty of Agriculture, University of Belgrade, for 90 days. Fish were fed with concentrate mixtures having 38% (A), 41% (B) and 44% (C) of proteins. The bigger share of the protein part in A were plant proteins (PP), in C fish meal (FM), while in B the share of FM and PP was approximately the same. Results showed significant differences between digestibility of different feed mixture. The digestibility of protein and fat were higher in fish fed diets with higher protein content. Digestibility of nitrogen-free extracts (NFE), energy and digestible energy was not statistically significant (p> 0.05) regardless of the level of protein in the diet. The results indicate that the increase in the digestibility of proteins is in accordance with the increase in protein content in the diet e.g. diets with higher content of FM

Center for Fishery and Applied Hydrobiology “Little Danube”, Experimental School Estate “Radmilovac”: Synergy of Research, Economy and Society

In every society, initiators and promoters of the development are individuals, teams or institutions with a vision, good ideas, seriousness, but above enthusiasm to work hard. They trace the road and drive activities related to research and/or economy. In the Serbian aquaculture sector such institutions is the Faculty of Agriculture and its Center for Fishery and Applied Hydrobiology (CEFAH) (or the “Little Danube”), which operates within the Experimental school estate “Radmilovac”. The Center started to be established in 2007. Unlike other similar Centers built by state resources intended for research and scientific work, the “Little Danube” was created much more as a result of enthusiasm of a group of researchers and their readiness to cooperate with national and international institutions, but also by enthusiasm of individuals ready to financially or materially help some of the Center’s programs. The Center’s activities are directed towards improving and developing the research and economy in aquaculture. Today the Center in “Radmilovac” and its laboratories located in the building of the Faculty of Agriculture represent an education and research polygon for aquaculture development. The education part is aimed at all levels: from pre-school and elementary school level by educational visits to the “Little Danube”, where they get to know different fish species and other aquatic organisms, their culture, fishing, fishing tools; to PhD level students and researchers that increase their knowledge and skills in the Center. CEFAH is a scientific polygon: in its aquaria, tanks, RAS systems, as well as in a number of earthen ponds a range of various experiments in different areas of aquaculture are carried out and knowledge is transferred directly in aquaculture economy. The development of Serbian aquaculture is directly affected by the connection of the Center with the economy through realization of biotechnology projects, fish selective breeding programs, and experiments

Superconductivity, phase fluctuations and the c-axis conductivity of bilayer high temperature superconductors

We present a theory of the interplane conductivity of bilayer high temperature superconductors, focusing on the effect of quantal and thermal fluctuations on the oscillator strengths of the superfluid stiffness and the bilayer plasmon. We find that the opening of the superconducting gap and establishment of superconducting phase coherence each lead to redistribution of spectral weight over wide energy scales. The factor-of-two relation between the superfluid stiffness and the change below $T_c$ in the oscillator strength of the absorptive part of the conductivity previously derived for single-layer systems, is found to be substantially modified in bilayer systems.Comment: 11 pages, 14 figure

Correlation between the Josephson coupling energy and the condensation energy in bilayer cuprate superconductors

We review some previous studies concerning the intra-bilayer Josephson plasmons and present new ellipsometric data of the c-axis infrared response of almost optimally doped Bi_{2}Sr_{2}CaCu_{2}O_{8}. The c-axis conductivity of this compound exhibits the same kind of anomalies as that of underdoped YBa_{2}Cu_{3}O_{7-delta}. We analyze these anomalies in detail and show that they can be explained within a model involving the intra-bilayer Josephson effect and variations of the electric field inside the unit cell. The Josephson coupling energies of different bilayer compounds obtained from the optical data are compared with the condensation energies and it is shown that there is a reasonable agreement between the values of the two quantities. We argue that the Josephson coupling energy, as determined by the frequency of the intra-bilayer Josephson plasmon, represents a reasonable estimate of the change of the effective c-axis kinetic energy upon entering the superconducting state. It is further explained that this is not the case for the estimate based on the use of the simplest ``tight-binding'' sum rule. We discuss possible interpretations of the remarkable agreement between the Josephson coupling energies and the condensation energies. The most plausible interpretation is that the interlayer tunneling of the Cooper pairs provides the dominant contribution to the condensation energy of the bilayer compounds; in other words that the condensation energy of these compounds can be accounted for by the interlayer tunneling theory. We suggest an extension of this theory, which may also explain the high values of T_{c} in the single layer compounds Tl_{2}Ba_{2}CuO_{6} and HgBa_{2}CuO_{4}, and we make several experimentally verifiable predictions.Comment: 16 pages (including Tables) and 7 figures; accepted for publication in Physical Review

Penetration of Josephson vortices and measurement of the c-axis penetration depth in Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+\delta}: Interplay of Josephson coupling, surface barrier and defects

The first penetration field H_{J}(T) of Josephson vortices is measured through the onset of microwave absorption in the locked state, in slightly overdoped $\rm{Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}}$ single crystals (T_{c} ~ 84 K). The magnitude of H_{J}(T) is too large to be accounted for by the first thermodynamic critical field H_{c1}(T). We discuss the possibility of a Bean-Livingston barrier, also supported by irreversible behavior upon flux exit, and the role of defects, which relates H_{J}(T) to the c-axis penetration depth $\lambda_{c}(T)$. The temperature dependence of the latter, determined by a cavity perturbation technique and a theoretical estimate of the defect-limited penetration field are used to deduce from H_{J}(T) the absolute value of $\lambda_{c}(0)=(35 \pm 15) \mu m$.Comment: 9 pages, 6 figure

Possibilities of Improvement of Production Traits of the Carp (Cyprinus Carpio) by Selective Breeding

Selective breeding for growth rate in common carp (Cyprinus carpio L.) has not been actively pursued after some early unsuccessful selection experiments. Prerequisite for successful selective breeding is accurate and objective evaluation of genetic parameters used in the planning and implementation of selection methods. The aim of this work was to assess the possibilities of improving production traits (weight, length and height) that are related to the growth of carp, through selection. Estimated variation and heritabilities were significantly high for all examined characteristics. Based on the obtained results can be expected to improve growth rate of common carp through selective breeding