An antimicrobial peptide that inhibits translation by trapping release factor trap.

Apidaecin (Api) belongs to the group of proline-rich antimicrobial peptides (PrAMPs), which are produced by insects and mammals and protect the host from bacterial infection. PrAMPs enter the bacterial cell, bind to the ribosome, and inhibit protein synthesis. Biochemical characterization and recent high-resolution crystal structures have shown that most PrAMPs obstruct the nascent peptide exit tunnel and the peptidyl transferase center in the ribosome and block the initiation step of translation. Despite the lack of the structural information about the Api-bound ribosome, its similarities with the other PrAMPs suggested that Api also inhibits translation initiation. However, our toeprinting experiments in a cell free translation system revealed that Api does not inhibit initiation but, instead, stalls the ribosome at the stop codon. Isolation of Api-resistant E. coli mutants with alterations in class-1 release factors RF1 and RF2, indicated that Api may interfere with the functions of these factors and/or their association with the ribosome. Consistently, our high-resolution cryo-EM structures of ribosomes complexed with Api showed that Api establishes interactions with the ribosomal exit tunnel and with the functionally important conserved GGQ motif of RF1. Furthermore, kinetic studies revealed that Api does not prevent the release of the nascent peptide chain but impedes the dissociation of RF from its binding site in the ribosome. By trapping RF1 and RF2 in the ribosome, Api leads to depletion of free class-1 RFs in the cell, resulting in inhibition of protein synthesis and cell growth arrest. Importantly, the Api-dependent depletion of RFs facilitates premature stop codon read-through. We envision the possibility that similar trapping of RFs on eukaryotic ribosomes could aid in relieving the effects of human genetic diseases caused by premature stop-codons

Faddeev Calculations of Proton-Deuteron Radiative Capture with Exchange Currents

pd capture processes at various energies have been analyzed based on solutions of 3N-Faddeev equations and using modern NN forces. The application of the Siegert theorem is compared to the explicit use of $\pi$- and $\rho$-like exchange currents connected to the AV18 NN interaction. Overall good agreement with cross sections and spin observables has been obtained but leaving room for improvement in some cases. Feasibility studies for 3NF's consistently included in the 3N continuum and the 3N bound state have been performed as well.Comment: Minor changes in notation, ps files for figure

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

Zmienność ofert cenowych przewoźników pasażerskich na przykładzie trasy Warszawa - Bruksela

In the study, the authors dealt with the price offer of four air carriers on the Warsaw – Brussels route. There were two traditional carriers (LOT Polish Airlines and Lufthansa) and two low-cost carriers (Ryanair and Wizz Air). The analysis considered changes in the ticket prices for a flight on a specific day over six months. A diversified pricing policy was found. Low-cost carriers and Lufthansa changed prices frequently but to a small extent. On the other hand, the cost of a ticket on Polish airlines was gradually increasing, the fastest in the last month before the flight. To minimize the ticket price at PLL LOT, a reservation had to be made at least three months before the flight. The lowest price of a Lufthansa and Ryanair ticket occurred a month before departure. On the other hand, at Wizz Air, the final price was lower than that offered at the beginning of the study

Technologies for retrieving sediment cores in Antarctic subglacial settings

Accumulations of sediment beneath the Antarctic Ice Sheet contain a range of physical and chemical proxies with the potential to document changes in ice sheet history and to identify and characterize life in subglacial settings. Retrieving subglacial sediments and sediment cores presents several unique challenges to existing technologies. This paper briefly reviews the history of sediment sampling in subglacial environments. It then outlines some of the technological challenges and constraints in developing the corers being used in sub-ice shelf settings (e.g. George VI Ice Shelf and Larsen Ice Shelf), under ice streams (e.g. Rutford Ice Stream), at or close to the grounding line (e.g. Whillans Ice Stream) and in subglacial lakes deep under the ice sheet (e.g. Lake Ellsworth). The key features of the corers designed to operate in each of these subglacial settings are described and illustrated together with comments on their deployment procedures

Systeme multidetecteur pour la recherche et l'etude d'isomeres de spin eleve et de haute energie produits dans des reactions nucleaires induites par ions lourds

SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc