mRNA翻译起始区的结构改变对几个外源基因翻译的影响

为观察ｍＲＮＡ翻译起始区结构与基因表达的关系,利用密码子的简并性,在不改变表达产物氨基酸序列的前提下定点突变几个外源基因的５′端若干位点,使基佤表达载体重组后转录形成的ｍＲＮＡ翻译起始区结构发生改变。经ＳＤＳ－ＰＡＧＥ等分析证实这些改变大大提高了外源基因的表达水平,ＲＮＡｄｏｔｂｌｏｔ表明突变与非突变基因转录水平差别不大,表达水平的提高主要由于翻译效率的提高,ｍＲＮＡ翻译起始区二级结构预测提示其生     

枯草杆菌核糖体蛋白质突变对碱性蛋白酶基因表达的影响

用枯草杆菌体外转录-翻译偶联系统检测13种19株枯草杆菌核糖体蛋白质突变对碱性蛋白酶基因表达的影响,发现10种13株核糖体蛋白质突变能影响碱性蛋白酶基因的表达。其中依赖链霉素突变核糖体几乎不能翻译碱性蛋白酶mRNA。依赖链霉素突变在翻译层次抑制碱性蛋白酶基因的表达,但对中性蛋白酶基因的表达没有影响。在碱性蛋白酶mRNA翻译起始区有一个复合二级结构,用体外突变方法破坏其中一个,翻译效率提高8.2倍。依赖链霉素突变和抗链霉素突变核糖体的高级结构不同,与碱性蛋白酶mRNA 5'端片段的亲合力也有差异。由于碱性蛋白酶mRNA翻译起始区的复合二级结构和低起始强度以及依赖链霉素突变核糖体高级结构的改变,使依赖链霉素突变核糖体不能翻译碱性蛋白酶mRNA。     

基因表达与mRNA结构的关系

基因的转录调控和转录后水平的调控在基因表达过程中起着重要作用。mRNA的结构与基因表达调控的关系非常密切。目前对于mRNA结构对表达的影响因素,主要集中于起始密码子和S-D序列的结构和间隔长度、基因和基因间的间隔区序列和长度,5’末端与3’末端非翻译区、多聚（A）尾、内含子序列对翻译起始效率、发夹结构对mRNA的稳定性的影响和mRNA翻译起始区等对基因表达影响。     

一种优化翻译起始效率的方法

本文以人分裂细胞核抗原(PCNA)基因作为目的基因,把包括PCNA基因5′端非翻译区(5′NTR)的24bp和编码38个氨基酸114 bp的顺序插入pTZ19R,构建与LacZ’5′端的融合基因。用寡核苷酸定点突变法在PCNA 5′NTR形成SD顺序,再用PCR法在SD顺序左右两侧分别随机突变6个和7个碱基,使它们与结构基因5′端顺序自发地形成各种可能的翻译起始区(TIR)二级结构。重组质粒转化JM109(DE3),以T7 RNA聚合酶-T7启动子调控转录。对288个重组子的β-gal活性测定表明,不同重组的表达量可相差55倍,其中9个表达量不同的重组子的RNA dot blot证实它们在转录水平无明显表达差异。由此提示,该研究策略和方法能有效地改变目的基因的TIR二级结构和捕获具有高翻译起始效率的表达克隆。     

基于mRNA 5'端TIR区二级结构优化提高重组sTNFαRI在大肠杆菌中的表达水平

目的:通过优化PET11b-s TNFαRI 5'mRNA翻译起始区(TIR)二级结构从而提高可溶性肿瘤坏死因子I型受体(sTNFαRI)在大肠杆菌[E.coli BL21(DE3)]中的表达水平。方法:通过对PET11b-s TNFαRI mRNA 5'端TIR区二级结构的自由能及核苷酸位置熵分析,设计相应的引物对mRNA 5'翻译起始区(TIR)相应密码子进行突变,从而使核糖体结合位点(RBS)及起始密码子(AUG)暴露于发夹结构之外,此外将p ET11b核糖体结合位点由GAAGGAGA突变为GAAGAA,以利于翻译复合体的组装以及翻译起始。通过基因克隆的方法将5'端TIR区优化后的序列与s TNFαRI序列一起克隆到p ET11b载体中,并转化大肠杆菌BL21(DE3),阳性转化子经IPTG诱导表达,SDS-PAGE和Western blot检测。结果:通过对PET11b-s TNFαRI 5'TIR mRNA二级结构优化,经SDS-PAGE和Western blot分析表明重组s TNFαRI的表达水平较优化前提高50%~60%。结论:通过对重组载体翻译起始区(TIR)mRNA序列的二级结构优化可以有效提高目的蛋白的表达水平,对进一步工业化生产具有重要的应用价值。     

mRNA翻译起始区二级结构优化提高(R)-羰基还原酶的表达及催化效率

为了提高近平滑假丝酵母(Candida parapsilosis CCTCC M203011)的(R)-羰基还原酶在大肠杆菌中的表达水平及催化效率,对酶编码基因mRNA翻译起始区中+1～+78区进行二级结构的优化,并构建了相应的突变体。优化后mRNA翻译起始区的发夹结构明显减少,自由能显著下降(由原始的?9.5kcal/mol降至?5.0kcal/mol),使酶蛋白的表达水平及粗酶比活力分别比优化前提高了4～5倍和61.9%。在高底物浓度(5.0g/L2-羟基苯乙酮)下,优化突变株不对称转化效率较高,产物(R)-苯基乙二醇的光学纯度和产率分别为93.1%e.e.和81.8%,比优化前提高了27.5%和40.5%。研究结果表明:优化mRNA翻译起始区的二级结构,克服蛋白翻译启动的空间位阻,不仅能促进翻译的顺利进行,使目标蛋白得到高效表达,而且有利于蛋白空间结构的正确折叠,有效提高酶蛋白活力及生物催化功能。     

霍乱毒素A基因内部翻译调控元件具有翻译起始功能

通过大肠杆菌体外转录－体外翻译系统,证明霍乱毒素Ａ基因内部的翻译调控元件具有翻译起始功能,且其翻译起始效率较ｃｔｘＡ基因高得多,当ｃｔｘＡ的起始密码突变时,从该元件起始的翻译效率下降,说明基因内翻译起以ｃｔｘＡ翻译起始的调控。结果进一步证实了霍乱毒素Ａ、Ｂ亚工比例表达调控的翻译弱化－翻译偶联机理。     

5′端非翻译区对LT-B基因表达的影响

mRNA5＇端非翻译区的不同结构可影响基因表达,为了改善编码人毒素源性大肠杆菌热敏感肠毒素B亚单位的LT-B基因的表达水平,我们把该基因置于pBV220载体的P_RP_L串联启动子下游,构建了带有不同核苷酸组成的5＇端非翻译区的重组体。这些重组体分别在大肠杆菌HB101和DH5α中表达。结果表明,起始密码前有两个连续串联SD序列的LT-B基因的表达水平低于只有单个SD序列下的表达水平,而翻译偶联可使表达改善;用不同的SD序列LT-B基因的表达水平也有所不同,用基因本身SD序列可能要比用pBV220P_L启动子下游的SD序列好;在只含单个LT-B基因SD序列的重组体中,5＇端非翻译区序列的长短对LT-B基因表达没有什么影响;重组体在HB101中的表达水平高于在DH5α中的表达水平。     

PTC下游翻译重启导致NMD途径的逃逸

无义突变介导的mRNA降解(nonsense-mediated mRNA decay,NMD)途径是真核生物体内一种重要的mRNA监督质控机制,它降解含有由无义突变、错误剪接、移码突变等产生的提前终止翻译密码子(premature translation termination codon,PTC)的mRNA,从而防止这种mRNA翻译产生的截短型蛋白质对机体造成的伤害.研究发现,一些含有PTC的mRNA发生了NMD途径逃逸,但具体机制仍不清楚.本研究将成视网膜细胞瘤基因1(retinoblastoma gene 1,RB1)作为NMD途径的靶基因,构建mini-RB1基因,包括外显子1~14(c DNA)、内含子14-外显子15-内含子15和外显子16~27(c DNA)的三部分序列,将其构建到真核表达载体pc DNA 3.1(-)中.根据人类基因组突变数据库选择3个突变位点W99X、G310X和R467X,构建相应无义突变体.分别将mini-RB1基因野生型和无义突变体转入He La细胞进行表达.用qRT-PCR检测发现,W99X无义突变体与野生型相比mRNA的水平无显著差异.为了进一步证实mini-RB1(W99X)发生了NMD逃逸,利用NMD途径抑制剂放线菌酮和转录抑制剂放线菌素D,分别处理转入野生型的mini-RB1基因及其无义突变体mini-RB1(W99X)的哺乳动物细胞,发现mini-RB1基因无义突变体的mRNA水平与野生型无明显差异,说明含有W99X无义突变的mini-RB1基因的mRNA发生了NMD逃逸.Western印迹检测mini-RB1基因的蛋白质表达发现,在无义突变位点W99X下游重新起始了蛋白质的翻译,因此,PTC下游蛋白质翻译的重新起始可能是导致无义mRNA逃逸NMD途径监控的主要原因.     

PTC下游翻译的重新起始导致NMD途径的逃逸

无义突变介导的mRNA降解（nonsense mediated mRNA decay, NMD）途径是真核生物体内一种重要的mRNA监督质控机制, 它降解含有由无义突变、错误剪接、移码突变等产生的提前终止翻译密码子（premature translation termination codon, PTC）的mRNA, 从而防止这种mRNA翻译产生的截短型蛋白质对机体造成的伤害. 研究发现, 一些含有PTC的mRNA发生了NMD途径逃逸, 但具体机制仍不清楚.本研究将成视网膜细胞瘤基因1 (retinoblastoma gene 1, RB1)作为NMD途径的靶基因, 构建mini-RB1基因,包括外显子1～14(cDNA)、内含子14 外显子15 内含子15和外显子16～27(cDNA) 的三部分序列, 将其构建到真核表达载体pcDNA 3.1(-)中.根据人类基因组突变数据库选择3个突变位点W99X、G310X和R467X, 构建相应无义突变体.分别将mini RB1基因野生型和无义突变体转入HeLa细胞进行表达.用qRT-PCR检测发现, W99X无义突变体与野生型相比mRNA的水平无显著差异.为了进一步证实mini- RB1（W99X）发生了NMD逃逸, 利用NMD途径抑制剂放线菌酮和转录抑制剂放线菌素D, 分别处理转入野生型的mini RB1基因及其无义突变体mini-RB1（W99X）的哺乳动物细胞, 发现mini-RB1基因无义突变体的mRNA水平与野生型无明显差异, 说明含有W99X无义突变的mini-RB1基因的mRNA发生了NMD逃逸.Western印迹检测mini-RB1基因的蛋白质表达发现, 在无义突变位点W99X下游重新起始了蛋白质的翻译, 因此,PTC下游蛋白质翻译的重新起始可能是导致无义mRNA逃逸NMD途径监控的主要原因.     

Pure translation display

Methods such as monoclonal antibody technology, phage display, and ribosome display provide genetic routes to the selection of proteins and peptides with desired properties. However, extension to polymers of unnatural amino acids is problematic because the translation step is always performed in vivo or in crude extracts in the face of competition from natural amino acids. Here, we address this restriction using a pure translation system in which aminoacyl-tRNA synthetases and other competitors are deliberately omitted. First, we show that such a simplified system can synthesize long polypeptides. Second, we demonstrate "pure translation display" by selecting from an mRNA library only those mRNAs that encode a selectable unnatural amino acid upstream of a peptide spacer sequence long enough to span the ribosome tunnel. Pure translation display should enable the directed evolution of peptide analogs with desirable catalytic or pharmacological properties.     

An efficient mammalian cell-free translation system supplemented with translation factors

Development of an efficient cell-free translation system from mammalian cells is an important goal. We examined whether supplementation of HeLa cell extracts with any translation initiation factor or translational regulator could enhance protein synthesis. eIF2 (eukaryotic translation initiation factor 2) and eIF2B augmented translation of capped, uncapped and encephalomyocarditis virus-internal ribosome entry site-promoted mRNAs. eIF4E specifically stimulated capped mRNA translation, while p97, a homologue to the C-terminal two-thirds of eIF4G, increased uncapped mRNA translation. When the HeLa cell extract was supplemented with a combination of eIF2, eIF2B, and p97, the capacity to synthesize a protein from an uncapped mRNA became comparable to that from the capped counterpart stimulated with a combination of eIF2, eIF2B, and eIF4E. A dialysis method rendered the HeLa cell extract capable of synthesizing proteins for 36h, and the yield was augmented when supplemented with initiation factors. In contrast, the productivity of a rabbit reticulocyte lysate was not enhanced by this method. Collectively, the translation factor-supplemented HeLa cell extract should become an important tool for the production of recombinant proteins.     

Chloroplast translation regulation

Chloroplast gene expression is primarily controlled during the translation of plastid mRNAs. Translation is regulated in response to a variety of biotic and abiotic factors, and requires a coordinate expression with the nuclear genome. The translational apparatus of chloroplasts is related to that of bacteria, but has adopted novel mechanisms in order to execute the specific roles that this organelle performs within a eukaryotic cell. Accordingly, plastid ribosomes contain a number of chloroplast-unique proteins and domains that may function in translational regulation. Chloroplast translation regulation involves cis-acting RNA elements (located in the mRNA 5′ UTR) as well as a set of corresponding trans-acting protein factors. While regulation of chloroplast translation is primarily controlled at the initiation steps through these RNA-protein interactions, elongation steps are also targets for modulating chloroplast gene expression. Translation of chloroplast mRNAs is regulated in response to light, and the molecular mechanisms underlying this response involve changes in the redox state of key elements related to the photosynthetic electron chain, fluctuations of the ADP/ATP ratio and the generation of a proton gradient. Photosynthetic complexes also experience assembly-related autoinhibition of translation to coordinate the expression of different subunits of the same complex. Finally, the localization of all these molecular events among the different chloroplast subcompartments appear to be a crucial component of the regulatory mechanisms of chloroplast gene expression.     

Translating translation: Regulated protein translation as a biomedical intervention

Altering the cellular response to internal and external stressors is essential for survival, hence the process of translation is exquisitely regulated to rapidly change the proteomic profile upon physiological challenges. We recently reported that genetic and pharmacological manipulation of translation may be beneficial in the treatment of Parkinson disease (PD). Using two Drosophila models of PD, we showed that altering the regulation of protein translation is sufficient to ameliorate the phenotypes of these models, including neurodegeneration, mitochondrial defects and behavioral deficits. Previous studies implicating translation regulation in lifespan extension further implicates this as an important mechanism that can mediate cell protective pathways, not just for age-related diseases such as PD, but also of aging itself. As such, translation regulation represents a convergent target for therapeutic interventions. Here we highlight the therapeutic potential of translation regulation in disease and describe how determining profiles of protein synthesis may help in the fight for disease prevention and healthy aging.     

Lost in translation

Some view social constructivism as a threat to the unique objectivity of science in describing the world. But social constructivism merely observes the process of science and can offer ways for science to regain public esteem.Political groups, civil organizations, the media and private citizens increasingly question the validity of scientific findings about challenging issues such as global climate change, and actively resist the application of new technologies, such as GM crops. By using new communication technologies, these actors can reach out to many people in real time, which gives them a huge advantage over the traditional, specialist and slow communication of scientific research through peer-reviewed publications. They use emotive stories with a narrow focus, facts and accessible language, making them often, at least in the eyes of the public, more credible than scientific experts. The resulting strength of public opinion means that scientific expertise and validated facts are not always the primary basis for decision-making by policy-makers about issues that affect society and the environment.The scientific community has decried this situation not only as a crisis of public trust in experts but more so as a loss of trust in scientific objectivity. The reason for this development, some claim, is a postmodernist perception of science as a social construction [1]. This view claims that context—in other words society—determines the acceptance of a scientific theory and the reliability of scientific facts. This is in conflict with the more traditional view held by most scientists, that experimental evidence, analysis and validation by scientific means are the instruments to determine truth. ‘Social constructivism'', as this postmodernist view on science has been called, challenges the ‘traditional'' view of science: that it is an objective, experiment-based approach to collect evidence that results in a linear accumulation of knowledge, leading to reliable, scientifically proven facts and trust in the role of experts.However, constructivists maintain that society and science have always influenced one another, thereby challenging the notion that science is objective and only interested in uncovering the truth. Moderate social constructivism merely acknowledges a controversy and attempts to provide answers. The extreme interpretation of this approach sustains that all facts and all parties—no matter how absurd or unproven their ‘facts'' and claims—should be treated equally, without any consideration for their interests [2].…scientific expertise and validated facts are not always the primary basis for decision-making by policy-makers about issues that affect society and the environmentThe truth might actually be somewhere in the middle, between taking scientific results as absolute truths at one extreme, and requiring that all facts and all actors should be given equal attention and consideration at the other. What is needed, however, is a closer connection and mutual appreciation between science and society, especially when it comes to science policy and making decisions that require scientific expertise. To claim that all perspectives are equally important when there is a lack of absolute facts—leading to an ‘all truths are equal'' approach to decision-making—is surely ridiculous. Nonetheless, societies are highly complex and sufficient facts are often not available when policy-makers and regulatory bodies have to make a decision. The aim of this essay is to argue that social construction and scientific objectivity can coexist and even benefit from one another.The question is whether social constructivism really caused a crisis of objectivity and a change in the traditional view of science? A main characteristic of the traditional view is that science progresses in isolation from any societal influences. However, there are historical and contemporary examples of how social mores influence the acceptability of certain areas of research, the direction of scientific research and even the formation of a scientific consensus—or in the words of Thomas Kuhn, of a scientific paradigm.Arrival at a scientific consensus driven by non-scientific factors will probably happen in a new research field when there is insufficient scientific information or knowledge to make precise claims. As such, societal factors can become determinants in settling disputes, at least until more information emerges. Religious and ethical beliefs have had such an impact on science throughout history. One could argue, for example, that the focus on research into induced pluripotent stem cells and the potency of adult stem cells is driven, at least in part, by religious and ethical objections to using human embryonic stem cells. Similarly, the near universal consensus that scientists should not clone humans is not based on scientific reason, but on social, religious and ethical arguments.Another example of the influence of non-scientific values on the establishment of a scientific consensus comes from the field of artificial intelligence. In the 1960s, a controversy erupted between the proponents of symbolic processing—led by Marvin Minsky—and the proponents of neural nets—who had been led by the charismatic Frank Rosenblatt. The publication of a book by Minsky and Seymour Papert, which concluded that progress in neural networks faced insurmountable limitations, coincided with the unfortunate death of Rosenblatt and massive funding from the US Department of Defense through the Defense Advanced Research Projects Agency (DARPA) for projects on symbolic processing. DARPA''s decision to ignore neural networks—because they could not foresee any immediate military applications—convinced other funding agencies to avoid the field and blocked research on neural nets for a decade. This has become known as the first artificial intelligence winter [3]. The military, in particular, has often had a major influence on setting the direction of scientific research. The atomic bomb, radar and the first computers are just some examples of how military interests drove scientific progress and its application.The traditional perception of science also supposes a gradual and linear accumulation of scientific knowledge. Whilst the gradual part remains undisputed, scientific progress is not linear. Theories are proposed, discussed, rejected, accepted, sometimes forgotten, rediscovered and reborn with modifications as part of an ever-changing network of scientific facts and knowledge. Gregor Mendel discovered the laws of inheritance in 1865, but his finding received scant attention until their rediscovery in the early 1900s by Carl Correns and Erich von Tschermak. Ignaz Semmelweis, a Hungarian obstetrician, developed the theory that puerperal fever or childbed fever is mainly transmitted by the poor hygiene of doctors before assisting in births. He observed that when doctors washed their hands with a chlorine solution before obstetric consultations, deaths in obstetrics wards were drastically reduced. The medical community ridiculed Semmelweis at the time, but the development of Louis Pasteur''s germ theory of disease eventually vindicated him [4].Another challenge to the traditional view of science is the claim that scientific facts are constructed. This does not necessarily imply that they are false: it acknowledges the process of independently conducted experiments, ‘trial and error'' approaches, collaborations and discussions, to establish a final consensus that then becomes scientific fact. Critics of constructivism claim that viewing scientific discovery this way opens the gate to non-scientific influences and arguments, thereby undermining factuality. However, without consensus on the importance of a discovery, no fact is sufficient to change or establish a scientific theory. In fact, classical peer review treats scientific discoveries as constructions essentially by taking apart the proposed fact, analysing the process of its determination and, based on the evidence, accepting or rejecting it.‘Social constructivism'' […] challenges the ‘traditional'' view of science: that it is an objective, experiment-based approach to collect evidence…Ultimately, then, it seems that social constructivism itself is not the sole or most important factor for changing the traditional view of science. Social, religious and ethical values have always influenced human endeavours, and science is no exception. Yet, there is one aspect of traditional science for which constructivism only has the role of an observer: public trust in scientific experts. Societies can resist the introduction of new technologies owing to their potential risks. Traditionally, the potential victims of such hazards—consumers, affected communities and the environment—had no input into either the risk-assessment process, or the decisions that were made on the basis of the assessment.The difficulty is that postmodern societies tend to perceive certain risks as greater compared with how they were viewed by modern or premodern societies, ostensibly and partly because of globalization and better communication [5]. As a result, the evaluation of risk increasingly takes into account political considerations. Each stakeholder inevitably defines risks and their acceptability according to their own agenda, and brings their own cadre of experts and evidence to support their claims. As such, the role of unbiased experts is undermined not only because they are similarly accused of having their own agenda, but also because the line between experts and non-experts is redrawn [5]. In addition, the internet and other communication technologies have unprecedentedly empowered non-expert users to broadcast their opinions. The emergence of so-called ‘pseudo-experts'', enabled by “the cult of the amateur” [6], further challenges the position of scientific experts. Trust is no longer a given for anyone, and even when people trust science, it is not lasting, and has to be earned for new information. This erosion of trust cannot be blamed entirely on the “cult of the amateur”. The German sociologist Ulrich Beck argued that when scientists make recommendations to society on how to deal with risks, they inevitably make assumptions that are embedded in cultural values, moving into a social and cultural sphere without assessing the public view of those values. Scientists thus presuppose a certain set of social and cultural values and judge everything that comes against that set as irrational [5].…without consensus on the importance of a discovery, no fact is sufficient to change or establish a scientific theoryRegardless of how trust in expertise was eroded, and how pseudo-experts have filled the gap, the main issue is how to assess the implications of scientific results and new technologies, and how to manage any risks that they entail. To gain and maintain trust, decision-making must consider stakeholder involvement and public opinion. However, when public participation attempts to accommodate an increasing number of stakeholders, it raises the difficult issue of who should be involved, either as part of the administrative process or as producers of knowledge [7,8]. An increasing number of participants in decision-making and an increasing amount of information can result in conflicting perspectives, different perceptions of facts and even half-truths or half-lies when information is not available, missing or not properly explained. There is no dominant perspective and all evidence seems subjective. This seems to be the nightmare scenario when ‘all truths are equal''.It is important to point out that the constructivist perspective of looking at the interactions between science and society is not an attempt to impose a particular world-view; it is merely an attempt to understand the mechanisms of these interactions. It attempts to explain why, for example, anti-GMO activists destroy experimental field trials without any scientific proof regarding the harm of such experiments. In addition, constructivism does not attempt to destroy the credibility of science, nor to overemphasize alternative knowledge, but to offer possibilities for wider participation in policy-making, especially in contentious cases when the lines between the public and experts are no longer clear [8]. In this situation, expert knowledge is not meant to be replaced by non-expert knowledge, but to be enriched by it.Nonetheless, the main question is whether scientific objectivity can prevail when science meets society. The answer should be yes. Even when several seemingly valid perspectives persist, objective facts are and should be the foundation of decisions taken. Scientific facts do matter and there are objective frameworks in place to prove or disprove the validity of information. Yet, in settling disputes, the decision must also be accountable to prevent loss of trust. By establishing frameworks for inclusive discussions and acknowledging the role of non-expert knowledge, either by indicating areas of public concern or by improving the communication of scientific facts, consent and thus support for the decision can be achieved.Moreover, scientific facts are important, but they are only part of an informational package. In particular, the choice of words and the style of writing can become more important than the factual content of a message. Scientists cannot communicate to the wider public using scientific jargon and then expect unconditional trust. People tend to mistrust things they cannot understand. To be part of a decision-making process, members of the public need access to scientific information presented in an understandable manner. The core issue is communication, or more specifically, translation: explaining facts and findings by considering the receiver and context, and adapting the message and language accordingly. Scientists must therefore translate their work. Equally important, they must do this proactively to take advantage of social constructivism and its view of science. By understanding how controversies around new scientific discoveries and scientific expertise arise, they can devise better communication strategies.…the internet and other communication technologies have unprecedentedly empowered non-expert users to broadcast their opinionsSome examples show how better interaction between science and society—such as the involvement of more stakeholders and the use of appropriate language in communication—can raise awareness and acceptability of previously contentious technologies. In Burkina Faso in 1999, Monsanto partnered with Africare to provide farmers with GM cotton to address pest resistance to pesticides and to increase yields. The plan was originally met with suspicion from the public and public research institutes, but the partners managed to build trust among the different stakeholders by providing transparent and correct information. The project started with a public–private partnership. By being open about their motives, including profit-making, and acknowledging and discussing any potential risks, the project gradually achieved the full support of the main partners [9]. Another challenge was the relationship between scientists and journalists. By using scientific communicators that were both open to dialogue and careful to maintain the discussion within scientific boundaries, the relationship with the press improved [10]. In this case, efforts to translate scientific knowledge included transparency of information and contextualizing its delivery, as well as an increasingly wider participation of stakeholders in the development and commercialization of GM cotton.…scientists[…]should consider proactively translating their research for a wider audience […] in an inclusive and contextualized mannerWhen the Philippines, the first Asian country to adopt a GM food, approved Bt maize, environmental NGOs and the Catholic Church opposed the crop with regular protests. These slowly dissipated as farmers gradually adopted Bt maize [11] and the reporting media focused less on sensationalist stories [12]. Between 2000 and 2009, media coverage contributed substantially to a mostly positive (41%) or neutral (38%) public perception of biotechnology in the Philippines [12]. Most newspaper reports focused on the public accountability of biotechnology governance and analysed the validity of scientific information, together with the way in which conflicts in biotechnology research were managed. Science writers translated scientific facts into language that the wider public could understand. In addition, sources in which the public placed trust—either scientists or environmentalists—were cited in the media, which helped to facilitate public discussion [12]. In this case, the efforts of science writers to provide balanced, well-informed coverage, as well as a platform for public discussions, effectively translated the scientific facts and improved public opinion of Bt maize.Constructivism is not a threat to science. It is a concept that looks at the components and the processes through which a scientific theory or fact emerges; it is not an alternative to these processes. In fact, scientists should consider embracing constructivism, not only to understand what happens with the products of their labour beyond the laboratory, but also to understand the forces that determine the fate of scientific developments. We live in a complex world in which individual actors are empowered through modern communication tools. This might make it more challenging to prove and maintain scientific objectivity, but it does not make it unnecessary. Public decision-making requires an objective fact base for all decisions concerning the use of scientific discoveries in society. If scientists want to prevent their messages from being misunderstood or hijacked for political purposes, they should consider proactively translating their research for a wider audience themselves, in an inclusive and contextualized manner.? Open in a separate windowMonica Racovita     

Lost in translation

Protein synthesis is an efficient and vital mechanism mediated by the ribosomes. In all living organisms, it allows an accurate correspondence between the genetic information and the newly synthesized polypeptides. The process of translation needs accurate quality-control systems to ensure the correct readout of the genetic data at the cellular level. Among them, bacteria did develop a specific mechanism referred to as "trans-translation", ensuring the recycling of stalled translating ribosomes and the degradation of incomplete nascent proteins when incomplete messenger RNAs (mRNAs) are translated. tmRNA (transfer messenger RNA) and SmpB (small protein B) are the main components of that process. Recent biochemical, genetic and structural data provide insights on how the tmRNA-SmpB complex accomplishes its duty, allowing a deeper understanding of the intricate links between trans-translation, bacterial survival and virulence.