翻译过程研究:回顾与展望

翻译过程研究是不可或缺的一部分,对翻译学的建设和发展具有较强的意义。从经验之谈、理论演绎、实证研究三个方面论述了学界关于翻译过程的研究。     

翻译正确的保证

翻译正确的保证严锦文,姜嘉娴（扬州大学农学院生化教研室,扬州２２５００１）关键词翻译翻译是一个十分复杂的过程,而翻译产生错误的频率却是很低的,大约接近于１０－４。这么低的错误频率在合成含１００、３００及１０００个氨基酸残基的无错误蛋白质的几率依次为０...     

鸡卵清蛋白表达调控

简要介绍鸡卵清蛋白,综述其基因结构和表达调控,表达调控从染色质水平、转录水平和翻译水平三个方面进行综述。     

RNA翻译的复杂性：不翻译、部分翻译、从头翻译及过度翻译

经典分子生物学的中心法则描述了遗传信息的传递方向.中心法则认为RNA只有通过翻译产生蛋白质才在生命活动中发挥功能.但是随着分子生物学的发展,很多RNA其本身就可以承担生命学功能.而且RNA的形式也不仅仅只有线性这一种.本文总结了RNA转录后命运的4种形式:不翻译、部分翻译、从头翻译和过度翻译.RNA命运的多样性使得对于翻译的理解比经典的中心法则规定的内容将更加丰富、复杂.充分了解RNA转录后的命运,对以后研究RNA的功能提出了更高的要求,也为我们真正而全面地了解RNA的功能提供了可能.     

中医术语英译标准化与翻译的文化取向

重申中医术语英译标准化的意义、目标并探讨WHO西太区、世界中医药学会联合会等对中医名词术语翻译的标准化中翻译文化取向的意义。针对目前对中医术语国际标准化翻译的重新审定,提出中医术语翻译的文化取向、民族性原则的重要性,重视国际交流中翻译的话语权,凸显翻译中的文化内涵,据此提出自己见解:(1)对中医文化负载词的概念的翻译应以音译或异化为主;(2)中药、方剂翻译应以音译为主。     

重金属对基因表达的影响

重金属对基因表达的调控研究是近几年的前沿课题。综述了重金属在转录前水平、转录水平、转录后水平、翻译水平、翻译后酶活性5个方面基因表达的影响。着重介绍了在转录前水平、转录水平、翻译后酶活性的影响。     

真核翻译起始因子5A在蛋白质合成中的功能及机制

在蛋白质合成过程中,除核糖体、氨酰 tRNA和mRNA外,还有多种翻译因子参与其中。真核翻译起始因子5A（eukaryotic translation initiation factor 5A, eIF5A）是维持细胞活性必不可少的翻译因子,在进化上高度保守。eIF5A是真核细胞中唯一含有羟腐胺赖氨酸（hypusine）的蛋白质,该翻译后修饰对eIF5A的活性至关重要。1978年,人们首次鉴定出eIF5A,认为它在翻译起始阶段促进第1个肽键的形成。直到2013年才证实它主要在翻译延伸阶段调控含多聚脯氨酸基序蛋白质的翻译。在经过四十多年研究后,人们对eIF5A的功能有了新的认识。近期基于核糖体图谱数据的分析表明,eIF5A能够缓解翻译延伸过程中核糖体在多种基序处的停滞,并不局限于多聚脯氨酸基序,并且它还能够通过促进肽链的释放增强翻译终止。此外,eIF5A还可以通过调控某些蛋白质的翻译,间接影响细胞内的各种生命活动。本文综述了eIF5A的多种翻译后修饰、在蛋白质合成和细胞自噬过程中的调控作用以及与人类疾病的关系,并与细菌及古细菌中的同源蛋白质进行了比较,探讨了该因子在进化中的保守性,以期为相关领域的研究提供一定的理论基础。     

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。     

真核生物mRNA非翻译区结构特征与mRNA翻译

真核生物中蛋白质合成通常在翻译水平受到调控,而mRNA非翻译区与mRNA翻译之间关系密切。真核生物mRNA非翻译区长度、mRNA二级结构、GC含量、顺式作用元件与反式作用因子、mRNA帽端结构和多聚腺苷酸尾等结构对翻译具有重要的调控作用。本文就真核生物mRNA非翻译区结构特征对其翻译的影响做一综述。     

医学英语的文体特征和翻译策略

随着现代科技的突飞猛进,作为其重要分支之一的现代医学进入跨越式发展阶段。与此同时,医学翻译一直在我国的科技翻译中占有重要地位。作为一个特殊的文体,医学翻译具有独特的文体特征和翻译准则。笔者介绍了医学英语的文体特征,并提出可行的翻译策略。     

Pacific treefrogs use temporal integration to differentiate advertisement from encounter calls

Male Pacific treefrogs, Hyla regilla, use advertisement and encounter calls in their reproductive communication. Encounter calls are produced when a male hears either advertisement or encounter calls at amplitudes that exceed his aggressive threshold for that call type, and they are believed to play a role in male spacing in a chorus. Aggressive thresholds of males for advertisement and encounter calls are plastic; males resume advertisement calling (i.e. accommodate) after repeated exposure to either advertisement or encounter calls that exceed their aggressive thresholds for that call type. Presentation of one call type does not elevate a male's aggressive threshold for the other call type, indicating that discrete neural ‘channels’ exist for processing advertisement versus encounter calls. Because these calls are spectrally highly similar, it is likely that they are differentiated in the central auditory system on the basis of their different temporal structure; pulses are repeated in advertisement and encounter calls at rates of approximately 100 pulses/s and 30 pulses/s, respectively. The present study tested whether consecutive advertisement-type interpulse intervals (IPIs) are required to activate the filter for advertisement calls. Males were accommodated to synthetic stimuli that differed in the proportion of advertisement versus encounter IPIs. Aggressive thresholds of males for the encounter call and advertisement call (monophasic type) were elevated 450% and 58%, respectively, following accommodation to a stimulus that had nine of each IPI type, arranged in an alternating sequence. Aggressive thresholds for the monophasic advertisement call were elevated 151%, however, when males were accommodated with stimuli that had two sets of eight to nine consecutive advertisement IPIs; consistent with previous work, aggressive thresholds for the encounter call were not significantly elevated. Aggressive thresholds for the advertisement call are typically elevated approximately four-fold following accommodation with that call type. These findings are consistent, therefore, with the hypothesis that several consecutive advertisement IPIs are required to activate the ‘advertisement channel’; if consecutive advertisement IPIs were not required, the stimulus that consisted of the same number of advertisement and encounter IPIs should have induced comparable elevations of the aggressive thresholds of males for advertisement and encounter calls. Selective filters for the advertisement call, therefore, appear to integrate information across many consecutive ‘correct’ IPIs. This integration process may contribute to a female's call preference.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .     

Does a trade‐off between current reproductive success and survival affect the honesty of male signalling in species with male parental care?

Recent theory predicted that male advertisement will reliably signal investment in paternal care in species where offspring survival requires paternal care and males allocate resources between advertisement and care. However, the predicted relationship between care and advertisement depended on the marginal gains from investment in current reproductive traits. Life history theory suggests that these fitness gains are also subject to a trade‐off between current and future reproduction. Here, we investigate whether male signalling remains a reliable indicator of parental care when males allocate resources between current advertisement, paternal care and survival to future reproduction. We find that advertisement is predicted to remain a reliable signal of male care but that advertisement may cease to reliably indicate male quality because low‐quality males are predicted to invest in current reproduction, whereas higher‐quality males are able to invest in both current reproduction and survival to future reproduction.     

Trade-offs between sexual advertisement and immune function in the pied flycatcher (Ficedula hypoleuca)

Good genes models of sexual selection assume that sexual advertisement is costly and thus the level of advertisement honestly reveals heritable viability. Recently it has been suggested that an important cost of sexual advertisement might be impairment of the functioning of the immune system. In this field experiment we investigated the possible trade-offs between immune function and sexual advertisement by manipulating both mating effort and activity of immune defence in male pied flycatchers. Mating effort was increased in a non-arbitrary manner by removing females from mated males during nest building. Widowed males sustained higher haematocrit levels than control males and showed higher expression of forehead patch height, suggesting that manipulation succeeded in increasing mating effort. Males that were experimentally forced to increase mating effort had reduced humoral immune responsiveness compared with control males. In addition, experimental activation of immune defence by vaccination with novel antigens reduced the expression of male ornament dimensions. To conclude, our results indicate that causality behind the trade-off between immune function and sexual advertisement may work in both directions: sexual activity suppresses immune function but immune challenge also reduces sexual advertisement.     

Intraspecific variation in advertisement call characteristics and acoustic strategies among male forest green tree frogs

Frogs are a representative taxon that use advertisement calls to aid in reproduction. In most frog species, calls vary with body size, and allometric constraints between body size and call frequency have been widely reported among anuran species. Although this variation is an important driver of sexual selection in frogs, male advertisement call strategies may also vary according to body size. In this study, we conducted playback experiments on the male forest green tree frog (Zhangixalus arboreus) to determine whether male advertisement call characteristics and strategies vary according to body size and the amplitude of intraspecific chorus noise. The results indicated that the calls of larger individuals are louder and lower than those of smaller ones, who call more frequently; moreover, the calls become lower, and the number of calls decreases, as noise levels increase. These findings suggest that forest green tree frog emits lower calls or refrains from calling when chorus noise increases, and that intraspecific variation in advertisement call characteristics can induce different strategies in response to chorus noise. Because advertisement call variation with body size is common among frog species, intraspecific variation in male advertisement call strategies may also be a common phenomenon.     

Aggressive Thresholds of Male Pacific Treefrogs for Advertisement Calls Vary with Amplitude of Neighbors' Calls

In breeding choruses, male Pacific treefrogs (H. regilla) produce advertisement and encounter calls. The role of each call type in establishing intermale spacing patterns was investigated by playing back, at various amplitudes, recordings of these vocalizations to resident males. The aggressive threshold of a male for each call type was defined as the lowest amplitude of playback that elicited encounter calls. Pacific treefrogs consistently had lower aggressive thresholds to playbacks of encounter calls than to playbacks of advertisement calls. Aggressive thresholds to playbacks of advertisement calls were positively correlated with the maximum amplitude of the advertisement calls of neighboring males, as measured at the position of the focal male.     

Will male advertisement be a reliable indicator of paternal care,if offspring survival depends on male care?

Existing theory predicts that male signalling can be an unreliable indicator of paternal care, but assumes that males with high levels of mating success can have high current reproductive success, without providing any parental care. As a result, this theory does not hold for the many species where offspring survival depends on male parental care. We modelled male allocation of resources between advertisement and care for species with male care where males vary in quality, and the effect of care and advertisement on male fitness is multiplicative rather than additive. Our model predicts that males will allocate proportionally more of their resources to whichever trait (advertisement or paternal care) is more fitness limiting. In contrast to previous theory, we find that male advertisement is always a reliable indicator of paternal care and male phenotypic quality (e.g. males with higher levels of advertisement never allocate less to care than males with lower levels of advertisement). Our model shows that the predicted pattern of male allocation and the reliability of male signalling depend very strongly on whether paternal care is assumed to be necessary for offspring survival and how male care affects offspring survival and male fitness.     

Fruit advertisement strategies in two Neotropical plant–seed disperser markets

Mutualisms can be seen as biological markets in which participating species exchange resources and services. Advertisements like the colors fleshy fruits are commonly used to attract mutualistic partners such seed dispersers. Although advertisements are common, the strategies employed in partner attraction and shaping the diversity of advertisements such as fruit colors remain largely unknown. Here, we adopt a market perspective on fruit color advertisement in multi-specific ensembles of fleshy-fruited plants and their avian seed dispersers. We develop and test the following non-exclusive hypotheses about fruit advertisement strategies in two Neotropical plant ensembles: (1) some low-rewarding plants offering low-energy fruits have fruit advertisements indistinguishable from those of some highly rewarding ones offering high-energy fruits thus forming possible mimicry pairs; (2) highly rewarding plants advertise their fruits with distinctive colors; and (3) fruit colors indicate the type of nutrient offered. We find support for two of the advertisement strategies. Further, we discuss how constraints on signal diversity may affect the evolution of advertisement strategies and we provide a perspective on which processes could characterize plant advertisement strategies in the biological market of seed-dispersal mutualisms.     

Multimodal Signaling in Male and Female Foot-Flagging Frogs Staurois guttatus (Ranidae): An Alerting Function of Calling

In multimodal communication, individuals use several sensory modalities for information transfer. We report on novel observations of foot‐flagging in the Bornean ranid frog Staurois guttatus that is temporally linked to advertisement calling. In addition, we document the first case of foot‐flagging in a female anuran as well as additional visual displays in both males and females including arm‐waving, vocal‐sac pumping and open‐mouth display. In males, advertisement calls and foot‐flags were given throughout most of the day, suggesting that acoustic and visual signals form a multicomponent and multimodal display. We tested the efficacy‐based alerting signal hypothesis of multimodal communication using acoustic playback experiments with males. This hypothesis predicts that an initial signal draws the receiver's attention to the location of a subsequent more informative signal. Several lines of evidence supported the alerting hypothesis. First, the latency between foot‐flags and advertisement calls was significantly higher than that between advertisement calls and foot‐flags, suggesting a functional linkage with calls drawing attention to foot‐flags. Secondly, advertisement calling had a signaling function with males responding significantly more often with both calls and foot‐flags compared with pre‐ and post‐playback control periods. Finally, and most notably, all males tested turned towards the playback stimulus, suggesting that the advertisement call serves to focus their attention on subsequent signals. We discuss the potential of multimodal signaling for conspecific and heterospecific communication and the circumstances under which such a multimodal communication system could evolve.     

Vocalizations of Hypsiboas goianus (Lutz, 1968) (Anura: Hylidae) in Central Brazil

Environmental and morphological factors and social context influence the vocalizations of anuran species. Herein, we observed the acoustic behavior of Hypsiboas goianus males from Central Brazil and analyzed the following calls: advertisement, short aggressive and long aggressive. The acoustic parameters of advertisement calls were not correlated with air temperature, mass or snout–vent length; however, the acoustic parameters of short aggressive calls were influenced by these variables. The temporal parameters of advertisement and short aggressive calls were classified as dynamic properties, while the dominant frequency was considered a static property. Dominant frequency is the most important variable to discriminate calls among individuals.     

Temporal order and the evolution of complex acoustic signals

The evolution of complex signals may be favoured by hidden preferences or pre-existing sensory biases. Females of two species of grey treefrogs (Hyla chrysoscelis and Hyla versicolor) were tested with combinations of a conspecific advertisement call and acoustic appendages. Appendages consisted of aggressive calls and segments of advertisement calls from conspecific males and males of three other species and bursts of filtered noise. When a wide variety of these acoustic appendages followed the advertisement call, the resulting compound signal was often more attractive than the same advertisement call alone. When the same appendages led advertisement calls, however, the compound signal was never more attractive and sometimes less attractive. The order effect was especially strong in tests of H. versicolor in which advertisement-call duration was decreased. These results cannot be explained by a general pre-existing bias for extra stimulation per se. Rather, order and other effects may constrain the evolution and subsequent modification of complex and extravagant signals, examples of which have been reported for a wide range of taxa.