Steerable optical tweezers for ultracold atom studies

We report on the implementation of an optical tweezer system for controlled transport of ultracold atoms along a narrow, static confinement channel. The tweezer system is based on high-efficiency acousto-optical deflectors and offers two-dimensional control over beam position. This opens up the possibility for tracking the transport channel when shuttling atomic clouds along the guide, forestalling atom spilling. Multiple clouds can be tracked independently by time-shared tweezer beams addressing individual sites in the channel. The deflectors are controlled using a multichannel direct digital synthesizer, which receives instructions on a sub-microsecond time scale from a field-programmable gate array. Using the tweezer system, we demonstrate sequential binary splitting of an ultracold $\rm^{87}Rb$ cloud into $2^5$ clouds.Comment: 4 pages, 5 figures, 1 movie lin

A laser based accelerator for ultracold atoms

We present first results on our implementation of a laser based accelerator for ultracold atoms. Atoms cooled to a temperature of 420 nK are confined and accelerated by means of laser tweezer beams and the atomic scattering is directly observed in laser absorption imaging. The optical collider has been characterized using Rb87 atoms in the |F=2,mF=2> state, but the scheme is not restricted to atoms in any particular magnetic substates and can readily be extended to other atomic species as well.Comment: (c) 2012 The Optical Society, 3 pages, 4 figures, 1 movie lin

Freshwater algae Cladophora glomerata and Vaucheria sp. from Serbia as sources of bioactive compounds: chemical analysis and biological activities

We examined potential biological activities of two taxa of freshwater algae, Cladophora glomerata and Vaucheria sp., from Serbia. The total phenolic and pigment contents, antioxidant potential, antimicrobial, antibiofilm activities, and cytotoxicity of the ethanol and acetone extracts were evaluated. The extracts were also subjected to Fourier transform infrared spectroscopy (FTIR) analysis. The levels of total phenolic compounds, chlorophylls a and b, and carotenoids varied based on both the algal taxa and the type of extracts. FTIR analysis showed the presence of lipids, unsaturated fatty acids, protein, carbohydrates, and phenols in the algal extracts. The extracts had moderate DPPH radical scavenging activity and lower reducing power compared with ascorbic acid. The antimicrobial activity expressed as minimum inhibitory concentrations ranged from 0.31 mg/mL to 10 mg/mL. The strains of Staphylococcus aureus and Bacillus cereus isolated from food samples, as well as S. aureus ATCC 25923, were the most sensitive. For the first time, the antibiofilm activity test revealed 98.7% inhibition of S. aureus biofilm formation. The extracts exhibited cytotoxic effects on choriocarcinoma JAR cells but without selectivity on normal fetal lung fibroblast MRC-5 cells. This is the first report on the biological activities of freshwater macroalgae from Serbia

Supplementary data for article: Stanojević, M.; Trifković, J.; Akšić, M. F.; Rakonjac, V.; Nikolić, D.; Šegan, S.; Milojković-Opsenica, D. Sugar Profile of Kernels as a Marker of Origin and Ripening Time of Peach (Prunus Persicae L.). Plant Foods for Human Nutrition 2015, 70 (4), 433–440. https://doi.org/10.1007/s11130-015-0515-4

Supplementary material for: [https://doi.org/10.1007/s11130-015-0515-4]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2001

Uticaj minazela plus na proizvodne rezultate i ekonomicnost tova junica

This paper presents the effects of the Minazel Plus zeolite product on the production performance – body weight, feed consumption and feed conversion, and economic performance of heifers in a fattening trial. The trial involved 22 female domestic spotted Simmental calves allocated to two groups (control C - ration without zeolite, and experimental E-I – ration with 0.2% Minazel Plus), each containing 11 calves with an average body weight of 139.09 kg at the beginning of the trial. The length of the trial period was 283 days. Ration included meadow hay and complete feed. Minazel Plus supplementation was provided through the feed concentrate. The trial involved measurement of body weights of heifers and feed consumption across groups at 31, 61, 91, 121, 151 and 283 days of the trial. Results showed that, at the end of the trial, control heifers had an average body weight of 432.73 kg/calf and concentrate feed conversion of 5.234 kg/kg weight gain, whereas the respective values in E-I heifers were 435.91 kg/calf and 5.179 kg/kg weight gain. The cost of the weight gain produced was higher by 0.33% (0.31 RSD/kg) in C calves than in E-I heifers, whereas the economic performance of the experimental animals receiving diet with Minazel Plus (0.2%) was higher by 0.29%.U radu su prikazani efekti zeolitskog preparata Minazel Plus na proizvodne rezultate –telesnu masu, konzumaciju i konverziju hrane i ekonomičnost tova ženske junadi u tovu. U ogledu je bilo 22 ženske teladi domaće šarene rase u tipu simentalca, podeljih u dve grupe (K grupa, obrok bez zeolitskog preparata i O-I grupa hranjena obrokom sa 0,2% Minazela Plus) sa po 11 grla u grupi, prosečne telesne mase na početku ogleda 139,09kg. Ogled je trajao 283 dana. Obrok je bio sastavljen od livadskog sena i potpune smeše, a Minazel Plus je dodavan preko koncentrovanog dela obroka. U toku ogleda merene su telesne mase junica i konzumacija hrane po grupama 31-og, 61-og, 91-og, 121-og, 150-og i na kraju ogleda - 283 dana. Rezultati istraživanja su pokazali da su junice iz kontrolne grupe na kraju ogleda imale prosečnu masu 432,73 kg/grlu i konverziju koncentrovane hrane 5,234 kg/kg prirasta, a grla iz O-I grupe prosečnu masu 435,91 kg/grlu i konverziju koncentrovane hrane 5,179 kg/kg prirasta. Cena koštanja proizvedenog prirasta bila je veća za 0,33% (0,31din/kg) kod K grupe u odnosu na O-I grupu, a u pogledu ekonomičnosti proizvodnje, ogledna grupa koja je obrokom dobijala Minazel-Plus (0,2%) imala je ekonomičniju proizvodnju za 0,29%

Supplementary data for article: Stanojević, M.; Trifković, J.; Akšić, M. F.; Rakonjac, V.; Nikolić, D.; Šegan, S.; Milojković-Opsenica, D. Sugar Profile of Kernels as a Marker of Origin and Ripening Time of Peach (Prunus Persicae L.). Plant Foods for Human Nutrition 2015, 70 (4), 433–440. https://doi.org/10.1007/s11130-015-0515-4

Supplementary material for: [https://doi.org/10.1007/s11130-015-0515-4]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2001

CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage

This is the final version. Available on open access from Nature Research via the DOI in this record. The Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we determine the structure of pIV from the f1 filamentous bacteriophage at 2.7 Å resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV subunits assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage egress. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.Wellcome TrustBiotechnology and Biological Sciences Research Council (BBSRC)Medical Research Council (MRC)Gordon and Betty Moore FoundationEuropean Research Council (ERC)Biotechnology and Biological Sciences Research CouncilAustralian Postgraduate Award (APA)IMB Research Advancement Awar

Intracellular directed evolution of proteins from combinatorial libraries based on conditional phage replication

Directed evolution is a powerful tool to improve the characteristics of biomolecules. Here we present a protocol for the intracellular evolution of proteins with distinct differences and advantages in comparison with established techniques. These include the ability to select for a particular function from a library of protein variants inside cells, minimizing undesired coevolution and propagation of nonfunctional library members, as well as allowing positive and negative selection logics using basally active promoters. A typical evolution experiment comprises the following stages: (i) preparation of a combinatorial M13 phagemid (PM) library expressing variants of the gene of interest (GOI) and preparation of the Escherichia coli host cells; (ii) multiple rounds of an intracellular selection process toward a desired activity; and (iii) the characterization of the evolved target proteins. The system has been developed for the selection of new orthogonal transcription factors (TFs) but is capable of evolving any gene—or gene circuit function—that can be linked to conditional M13 phage replication. Here we demonstrate our approach using as an example the directed evolution of the bacteriophage λ cI TF against two synthetic bidirectional promoters. The evolved TF variants enable simultaneous activation and repression against their engineered promoters and do not cross-react with the wild-type promoter, thus ensuring orthogonality. This protocol requires no special equipment, allowing synthetic biologists and general users to evolve improved biomolecules within ~7 weeks