Mapping thermal inertia, soil moisture and evaporation from aircraft day and night thermal data

There are no author-identified significant results in this report

Visualization of translation termination intermediates trapped by the Apidaecin 137 peptide during RF3-mediated recycling of RF1.

During translation termination in bacteria, the release factors RF1 and RF2 are recycled from the ribosome by RF3. While high-resolution structures of the individual termination factors on the ribosome exist, direct structural insight into how RF3 mediates dissociation of the decoding RFs has been lacking. Here we have used the Apidaecin 137 peptide to trap RF1 together with RF3 on the ribosome and visualize an ensemble of termination intermediates using cryo-electron microscopy. Binding of RF3 to the ribosome induces small subunit (SSU) rotation and swivelling of the head, yielding intermediate states with shifted P-site tRNAs and RF1 conformations. RF3 does not directly eject RF1 from the ribosome, but rather induces full rotation of the SSU that indirectly dislodges RF1 from its binding site. SSU rotation is coupled to the accommodation of the GTPase domain of RF3 on the large subunit (LSU), thereby promoting GTP hydrolysis and dissociation of RF3 from the ribosome

Tissue-specific regulation of translational readthrough tunes functions of the traffic jam transcription factor

Translational readthrough (TR) occurs when the ribosome decodes a stop codon as a sense codon, resulting in two protein isoforms synthesized from the same mRNA. TR has been identified in several eukaryotic organisms; however, its biological significance and mechanism remain unclear. Here, we quantify TR of several candidate genes in Drosophila melanogaster and characterize the regulation of TR in the large Maf transcription factor Traffic jam (Tj). Using CRISPR/Cas9-generated mutant flies, we show that the TR-generated Tj isoform is expressed in a subset of neural cells of the central nervous system and is excluded from the somatic cells of gonads. Control of TR in Tj is critical for preservation of neuronal integrity and maintenance of reproductive health. The tissue-specific distribution of a release factor splice variant, eRF1H, plays a critical role in modulating differential TR of leaky stop codon contexts. Finetuning of gene regulatory functions of transcription factors by TR provides a potential mechanism for cell-specific regulation of gene ex-pression

LINGUÍSTICA DE CORPUS E ENSINO DE INGLÊS INSTRUMENTAL

Este artigo tem como objetivo demonstrar a possibilidade de aplicação efetiva da linguística de corpus à prática de ensino de língua inglesa para fins específicos, considerando a indisponibilidade de recursos computacionais e softwares específicos da maioria das salas de aula. Para tanto, foram aplicadas sete atividades a um grupo de cinco alunos adultos, profissionais e estudantes da área de geografia, com nível de inglês pré-intermediário. Essas atividades foram divididas em duas aulas, com duração de noventa minutos cada e foram ministradas em língua materna. Ao final das duas aulas, constatou-se que todos os alunos realizaram as sete atividades sem grandes dificuldades, demonstrando a aplicabilidade da linguística de corpus em uma sala de aula sem recursos computacionais e a efetividade das atividades propostas. Essa efetividade foi devido à utilização de textos autênticos, da área de atuação dos alunos, o que tornou as aulas mais fidedignas

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

Translational recoding: Canonical translation mechanisms reinterpreted.

During canonical translation, the ribosome moves along an mRNA from the start to the stop codon in exact steps of one codon at a time. The collinearity of the mRNA and the protein sequence is essential for the quality of the cellular proteome. Spontaneous errors in decoding or translocation are rare and result in a deficient protein. However, dedicated recoding signals in the mRNA can reprogram the ribosome to read the message in alternative ways. This review summarizes the recent advances in understanding the mechanisms of three types of recoding events: stop-codon readthrough, -1 ribosome frameshifting and translational bypassing. Recoding events provide insights into alternative modes of ribosome dynamics that are potentially applicable to other non-canonical modes of prokaryotic and eukaryotic translation

Resources for the teacher from a semiotic mediation perspective.

Abstract The potential of ICT tools for learning have been extensively studied, with a main focus on their possible use by students and the subsequent benefits for them. However, there has been the tendency to underestimate the complexity of the teacher’s role in exploiting this potential. In this chapter, we assume a semiotic mediation perspective and discuss different kinds of resources which are offered to teachers to enhance the teaching–learning activity centred on the use of an ICT tool: by resource for the teacher we mean any artefact which may help the teacher accomplish her educational objectives. Taking a semiotic mediation perspective means to acknowledge the central role of signs in teaching–learning activity: the focus is on semiotic processes, specifically production of signs and their transformation. Fostering or guiding these processes is a crucial issue and a demanding task for the teacher. Consequently, from such a perspective, a resource for the teacher is any artefact that can help her promoting and sustaining the development of those semiotic processes. In this chapter, we discuss the teacher’s use of specific resources – namely written texts – with respect to the semiotic processes which she is expected to orchestrate in the different moments of the teaching sequence