All modes work fully as intended, with photo and voice translations being particularly useful. The conversations mode is the most complex aspect of the app, requiring the person you are speaking with to “join” the conversation using a device of their own – so, this is reserved for specific situations rather than off-the-cuff use.
Underneath, there are icons for history, phrasebook and settings. The key settings, available in-app unlike its Apple Translate rival, include having your phone speak the translations, increasingly slowing down the speed of audio translations to make them clearer, access to offline language translation and the ability to clear your translation history. While the phrasebook, again, adds to the feeling that this tool is a great travel companion – providing quick access to a wide range of basic phrases in a chosen language.
In terms of translation quality, My Language Lab found the Microsoft Translator app had a strong vocabulary, accurate text translation – even if it does require some personal revision – and no standout issues.
The Microsoft Translator app is simple to use and should be the go-to app for those who want digital translations – even if they aren’t an every day, or power, smartphone user. The app has a good range of features, too, making it scalable for those who may want to do more with their translations.
Platform: Android/iOS
Pros: Accessible; accurate for voice and text translation; useful additional features
Cons: Overly complex conversation mode
Score: 8/10
SayHi
Some awkward design choices but great for text translation
Stepping away from the big players like Google, Apple and Microsoft, there are a couple of popular options from less well-known companies. SayHi is one of them – and it’s also free to use.
The app brings a similar level of simplicity to competitors, with a large white background and two mic buttons at the bottom taking centre stage. The two mics make this an app focused on back and forth of voice translations, letting you quickly switch from translating a voice in one language to translating another voice in another.
The menu in the top left corner offers up additional conversation and image modes (both in beta). While settings lets you tweak some basic things like playing translations aloud and auto-saving images taken with the app’s in-built camera.
Unfortunately, the focus on recording voices back and forth does not play into the hands of the SayHi app’s capabilities. When it comes to general accuracy, My Language Lab found that translations regularly fell below an acceptable standard.
Fujitsu Ltd. on Thursday released a multilingual speech translation service that does not require users to operate devices by hand.
The service is designed for settings in which multilingual communication is needed amid a rise in the domestic population of non-Japanese speakers, such as medical facilities.
It automatically translates speech after identifying the voices and locations of users on the basis of sound picked up by directional microphones connected to tablet devices.
Fujitsu said that the voice recognition is highly accurate thanks to technology limiting the effects of background noise.
In addition to medical settings, the service is expected to be used at tourist sites.
The service is capable of translating English, Mandarin, Korean, French, Spanish, Portuguese, Indonesian, Thai, Vietnamese and Myanmar. It can display both simplified and traditional Chinese characters.
The product, which includes the tablet device, microphones and an app for the service, is priced at ¥16,500 per month. The company plans to sell 3,000 sets by the end of fiscal 2025.
The multilingual translation technology was developed in cooperation with the state-backed National Institute of Information and Communications Technology as part of efforts promoted by the Internal Affairs and Communications Ministry. The technology has been tested at medical and tourism facilities.
The Fujitsu service employs the speech translation service offered by Mirai Translate Co., which used the research by the NICT.
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By subscribing, you can help us get the story right.
Last year was the centenary of the establishment of the Nazi Party in Germany. In 1920, Adolf Hitler wasn’t yet the party’s leader, but he was one of its leading figures. Another five years would pass for the public to become aware of his thoughts and plans, as set forth in his book “Mein Kampf” (“My Struggle”). Its original title was “My Struggle: Four and a Half Years of Struggle against Lies, Stupidity and Cowardice.” Is the time ripe for a new look at and reassessment of this book?
“Mein Kampf” is considered one of the most influential books of the 20th century. In many countries, Israel among them, it’s considered dangerous, but elsewhere it has actually garnered appreciation today. Although it was translated into many languages already in the 1930s, no Hebrew translation of its two volumes exists. The book is viewed as “tainted,” a hate tract rife with gutter language, written by a young politician and frustrated artist. Still, a series of studies published in recent years, as well as popular literature and articles in the press, offer a new, realistic vantage point on it that’s unrelated to a neo-Nazi or far-right worldview.
The appearance of the scholarly annotated edition of the work in Germany five years ago stirred a furor, not least because the researchers, some of whom were involved in the publication, tried to justify the project by calling for the book’s historicization. The new German edition is part of the “young Hitler wave” that has been prominent in the world of research in the past decade, particularly in Germany. New biographies and articles have been reexamining the path followed by the young politician, from his service in World War I until his release from Landsberg Prison at the end of 1924.
“Mein Kampf” is notorious for being lengthy, clumsy and difficult to read. Other than translators, and researchers and editors of the academic editions – including the editors of the abridged Hebrew edition that appeared many years ago (“Chapters from ‘My Struggle,’” edited by Moshe Zimmermann and Oded Heilbronner, Akademon Publishers) – few people have read the entire book, or even most of it, according to the research. Hitler himself noted in his introduction that the book was aimed not at the general public but at Nazi Party faithful; he added that most people are lazy and impatient and don’t bother to read books unless they meet their expectations. In the Third Reich, too, the vast majority of Germans didn’t read the book. The comment that “After all, in ‘Mein Kampf’ Hitler claimed that…” was widespread in Germany, and during wartime also among its enemies, but as noted, few of those who uttered it had taken the trouble to read the whole book. It’s probably safe to say that today, too, young neo-Nazis read it very selectively.
The first volume of “Mein Kampf” appeared in the summer of 1925, in what was a particularly turbulent period. The Weimar Republic was in its first years and in dire straits, even seeming to be on the brink of collapse. One of the small, far-right groups that despised the republic was the Nazi Party, officially known as the National Socialist German Workers Party, headed by Hitler, whose activity was based in Bavaria. Following the party’s failed putsch attempt, in Munich in November 1923, he served about eight months in Landsberg Prison in Bavaria. Probably he knew that after his release he would be forbidden from speaking in public, which until then had been the main source of his political power. Political writing was meant to be a substitute. Apparently the “respite” from politics that was foisted on him enabled him to reprocess ideas he had harbored even before the putsch into a relatively solid worldview, which he continued to advocate until his suicide in 1945.
During this period, Hitler devised a new strategy for rehabilitating the party, his status in it and how he would go about toppling the republic. Gradually he started to see himself as a future führer (leader) of Germany. He planned to have the party run in the different elections held in the country during the 1920s and early ‘30s, which would result in his appointment as chancellor. He understood the mistake he had made in trying to overthrow the German army, and henceforth strove to cooperate with the military. Finally, Hitler chose to differentiate his relatively small party from the rest of the far right, to avoid cooperation with other groups and to emphasize its distinctive features.
In addition to addressing political and national questions, the first volume of “Mein Kampf” is intended to help cultivate the myth around its author’s image. The autobiographical elements are structured to show Hitler as a natural-born ideologist, politician and artist: his tragic life story in Vienna and Munich, his heroism in the war and his entry into politics as a rank-and-file member of the German Workers Party. His aim was to depict himself as a simple but intelligent person, a war hero who was willy-nilly caught up in political life and whose whole desire was to save Germany from the Jews and the communists.
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Volume 1 of “Mein Kampf” was written in patchwork fashion. Hitler dictated parts of it to his secretary, Rudolf Hess, and to other confidants. It contains long articles and speeches published before the putsch, particularly in the party organ the Völkischer Beobachter (People’s Observer). Historian Thomas Weber maintains that some sections were written in 1923 by a radical-conservative journalist named Victor von Koerber, who set down what Hitler told him or formulated in writing ideas that the latter provided to him orally.
In the summer of 1925, when the first volume was published, the reestablished Nazi Party was at a nadir and drew little attention in Germany. The book cost 12 marks, a hefty sum at a time when a loaf of bread sold for 1.30 marks. But “Mein Kampf” was an immediate, huge success, selling 10,000 copies on its publication. The haste to get the book into shops might explain the sloppy (some might say lack of) editing, the absence of a guiding theme throughout the book, the multiple contradictions and the clumsy wording – all of which made reading it a chore. The repetitive style of certain chapters look like an attempt by Hitler to apply the principles of spoken propaganda to the written word. When delivering propaganda orally, he maintained, it’s essential to repeat key words and sentences over and over.
Hitler in traditional Bavarian garb, 1923.Farabola / Leemage / AFP
Political worldview
The second volume, written during 1925, at Hitler’s home in the Bavarian town of Berchtesgaden and published a year and a half after the first book, was a commercial failure. In contrast to its predecessor, which set forth a life story (half invented), the second volume advanced a political worldview. The book contains dozens of speeches that Hitler had delivered before his imprisonment, and it also develops ideas its author had floated in the first volume, many of them relating to foreign policy. This volume is more coherent than the first, and the influence of Dietrich Eckart, Hitler’s ideological mentor, who died in 1923 and to whom the book is dedicated, is apparent in many of the chapters.
At the time, Hitler’s leadership was still in danger, and not all the party’s members and supporters approved of his political-social vision. Moreover, the situation in the German republic had stabilized, the agreement with the Soviet Union (Treaty of Rapallo, 1922) was being observed, and the United States turned out to be Weimar’s close ally. The election of Paul von Hindenburg as president in 1925 bolstered the strength of the conservative right, and the extreme right had to reinvent itself.
In its two volumes, “Mein Kampf” was supposed to reestablish Hitler’s leadership, which started in 1921 but was challenged while he was imprisoned, this time as a führer with a vision – that is, a leader by supreme grace not bound to any authority – and to show the Völkisch (ethno-nationalist) German right wing the truth: The republic’s flimsy racial and social foundations would not allow it to sustain itself over time.
Is “Mein Kampf” a dangerous book, then? Armin Mohler’s 1950 study “The Conservative Revolution in Germany” shows that Hitler’s book was part of a wave in the decade following World War I of autobiographies and political essays written by leading members of all the political camps in Germany. Figures on the extreme right published dozens of books explaining why Germany had lost the war, and laying out what could be corrected and the path to deliverance. Their language was often crass, offensive and pernicious. Examples are the books by veteran Nazis such as Alfred Rosenberg (“Immorality in the Talmud”), Artur Dinter (“The Sins of the Time”) and Ernst Graf zu Reventlow (“Für Christen, Nichtchristen, Antichristen,” published only in German).
In fact, a proper reading of “Mein Kampf” can provide a clear, substantive picture of Hitler’s worldview. Some sections offer a lucid, fundamental, far-right interpretation of recent historical events: the war, the defeat, the establishment of the Weimar Republic. The book expounds (albeit in crude language) on Hitler’s opposition to the popular demand voiced during the 1920s to have Germany return to its eve-of-war boundaries on the basis of the right of self-determination for all the peoples living within its historical borders.
It is clear today that one cardinal reason for the eruption of World War I was the national divisions in Europe and the fact that in various parts of the continent different national groups were intermixed. Like others in the German right, Hitler promised to correct this historic “wrong.” His objections to German colonialism in Africa are also based on arguments familiar today to many historians who indirectly justify his approach.
As an obsessive reader of political and historical literature, Hitler knew well the writings of, among others, Marx, Victor Adler, Lenin and Gustave Le Bon, and of course the works of such well-known racist antisemites as Count Gobineau, Houston Chamberlain, Hans Guenther and many others. His great interest in mobilizing the masses and taking control of the street was influenced both by Vienna mayor Karl Lueger, on the right, whom he admired from the period of his residence in the Austrian capital, and also by the communists, with whom he apparently had a brief fling in Munich in the months following World War I. Chapters like “Propaganda and Organization” and “Word-Concept and Organization” read as though they were written by Lenin or Le Bon, author of “Psychology of Crowds.” Guidelines for the rehabilitation of the Nazi Party after the failed putsch are also put forward as an orderly, clear plan of action driven by two basic tactics: recruitment of supporters and loyalists by means of political propaganda rallies, and control over the relations between the party’s leaders and its base – for example, via the political information that was to be made available to supporters i to cement their loyalty to the leadership.
A Turkish copy of Adolf Hitler's "Mein Kampf"REUTERS
The Jewish question
And now to the Jewish question. Historian Ian Kershaw is right when he asserts that “we do not know for certain why, nor even when, Hitler turned into a manic and obsessive antisemite.” In “Mein Kampf” itself it’s difficult to find the origins of the Holocaust, or even inklings of it. Hitler and the heads of his party did argue that the exposure of “12,000 or 15,000 Hebrews” to poison gas in the war would have saved the lives of millions of Germans – a comment that was interpreted in different ways. The famous Chapter 11 of the first volume, “People and Race,” is sometimes read with a shudder because of its harsh depictions of the Jews, and was later quoted by Josef Goebbels and by the SS newspaper The Black Corps. However, such sentiments were standard fare among certain segments of the German and European public at the time and were not unique to Hitler.
In any event, as contemporary critical writings have showed, until 1930 and in large measure until 1933, there was no great admiration for the book, but the number of its readers grew together with the party’s electoral strength. By 1933, about a quarter of a million copies of the popular edition had been sold. There were those who said unabashedly that the book was unreadable, and Hitler made a number of revisions for the readers’ benefit. In the 1932 edition, on the eve of his ascension to power, when interest in the Nazi Party grew internationally – he amplified the chapters dealing with foreign policy and in particular stressed his call for an alliance with Britain.
Of course, the picture changed following the establishment of the Third Reich. In 1933, the book was published for the first time in English, in the U.K., in an abridged edition, with a blurb that described Hitler as “a remarkable character, whose intense belief in his ideals won over a mighty nation.” A full American edition of the two volumes, published in 1939 by Houghton and Mifflin, before Kristallnacht, adopted an ambivalent approach. The editors made a point of stating their opposition to the violent ideas contained in the book, especially to its race theory, but described Hitler as having held from boyhood “a passionate belief that Germany must obtain a larger place in the sun… and set out to mobilize the whole nation for a new advance.” They add that the repetitions in the book reflect the personality of the author, and assert that “Mein Kampf” is, “above all, a book of feeling.”
During the era of the Third Reich, multiple editions of the book were published in Germany – more than a thousand. The difficulty in estimating their number is due to the contradictory data issued by Eher, the official publishing house of the Nazi Party, headed by Hitler’s “friend” Max Amann. The last edition appeared in December 1944, when the end of the Nazi regime loomed clearly. By then, more than 12 million unabridged copies had been sold in the Third Reich.
Following Germany’s defeat, sale of the book was banned, first by the occupying powers, and from 1949 on by the governments of both East and West Germany, though public and academic libraries acquired the (pre-1944) version with no limitations. Outside Germany and Austria, it was freely available. In Scandinavia and Britain the book enjoyed a resurgence of popularity in the 1970s, possibly because of the growing strength of a fascist far right. It’s worth recalling David Bowie’s short-lived fondness for Hitler and possibly his book in the 1970s. Today the book is available in bookstores, libraries and academic institutions, as well as on internet sites and in discussion groups around the world.
Starting in 2016, more than 70 years after “Mein Kampf” was banned in Germany, it again became available for purchase in bookstores there. A new annotated, critical edition, published by the Munich-based Institute for Contemporary History, consists of about a thousand pages of the original text and another thousand pages of notes and commentaries by the institute’s researchers.
The publication of the new German edition involved political and moral battles. It was a joint project of the Institute for Contemporary History and the government of the Free State of Bavaria, which had been granted the copyright by the American occupation forces in the region immediately following the war. However, in 2010, the Bavarian government dropped its support for the project for what it termed “moral” reasons, and the institute continued the work with its own funding and with support from academic bodies in Germany.
Hasn’t the time come to follow in Germany’s footsteps, and make available to Hebrew readers a translation of the full text with annotations to make it accessible to them? Not for a forgiving or understanding reading, but for a reading that relates to the book as a historical text.
Prof. Oded Heilbronner is a senior lecturer at the Shenkar College of Engineering, Art and Design, and also teaches at the Hebrew University of Jerusalem and at the Interdisciplinary Center, Herzliya .
In April 2016, comedian-actor Patton Oswalt's life was rocked upside down after his late wife of over a decade, Michelle McNamara, died in her sleep. His daughter Alice was only 7 years old when she lost her mom. While Oswalt may be a funnyman at heart, he fully admits that if he didn't have Alice, the grief and darkness would have drowned him. "Drinking would have been a problem. Binge-eating would have been a problem. I would have merely existed," he told The Guardian. "Having Alice was like: 'I've got to get up, I've got to make breakfast, I got to take care of this little life.' So, it's almost like I had freedom from choice because I had our daughter."
From the support of family, friends, each other, and Oswalt's now wife Meredith Salenger, they're healing. "I don't want her memories of me to be of a parent that's despairing even deeper than she is," he explained to People magazine. " . . . I went out of my way to deal with myself and just be there as a symbol of strength and happiness for her." It's clear as day the two are inseparable and we adore watching their relationship blossom. Read more about their father-daughter bond ahead!
Related: Yep, Kristen Bell and Dax Shepard Seem Like Pretty Cool Parents to Us; Here's the Proof
Communicating with others who speak a different language has gotten easier with technological advances. We can use translation apps on our mobile devices and built-in translation tools for our desktop applications. Luckily, Microsoft Outlook is one such desktop app with a translation tool, and the tool is available in Outlook for the web.
When you receive an email in another dialect, you have a few ways to translate it. You can adjust your settings to handle all incoming emails in another language the same way. Or you can do translations when needed.
How to Change Your Outlook Translation Setting for Incoming Mail
If you regularly receive emails that need to be translated, making a quick change in your settings to accommodate this need is a good way to go. Here’s how to do it in the Outlook desktop app.
Open Outlook and head to File > Options.
In the Outlook Options window, select Language on the left.
Scroll down on the right to Translation.
Pick an option at the top. You can choose Always translate, Ask me before translating, or Never translate. Obviously, you’ll want to select one of the first two options.
You can confirm the translation language, which should be set to your default already.
If there are languages other than your own that you do not want translations for, you can click Add a language to include it in the box at the bottom.
Click OK.
To navigate to the same setting in Outlook for the web, follow these steps.
Click Settings (gear icon) on the top right.
At the bottom of the sidebar, click View all Outlook settings.
On the furthest left, select Mail, and to the right, select Message Handling.
Under Translation, you have the same choices for Always, Ask, and Never.
Make your selection and click Save.
Depending on which option you select, your incoming messages will behave differently always to translate or ask before translating. But they work basically the same in the desktop app and Outlook for the web.
Using Always Translate
This is the quickest way to go if you regularly receive emails in another dialect. The translation takes only seconds (depending on your connection), and you’ll receive the translated text automatically.
You can see the text’s original language and can click Show Original to see it before the translation.
Using Ask Me Before Translating
For this setting, you’ll see an option at the top of the message for Translate message to: [language]. Click that, and you’ll see Outlook translate the text to your preferred language.
Like with the above setting, you can click Show Original to see the untranslated text. You also have options to turn on automatic translations as described earlier.
How to Perform a One-Time Translation for an Email
Maybe you prefer to keep your Translation setting at Never translate in Step 4 above and use Outlook to translate emails as they arrive.
Select the text you want to translate in the email by dragging your cursor through it.
Right-click and move your cursor to Translate in the shortcut menu.
You’ll then see the translation at the top of the pop-out window. You can also choose Translate Message to translate the text within the email itself or use the Translate button in the ribbon.
Communicate Quicker With Microsoft Outlook Translations
With both settings and one-time translations in the Microsoft Outlook desktop app and on the web, communicating in other languages doesn’t have to be difficult. You can use Outlook to translate emails effortlessly.
For additional help with translations, take a look at how to translate a PDF document.
A new business intelligence report released by Advance Market Analytics with title Online Translation Market Insights, Analytical Overview, Growth Factors, Demand and Forecast to 2025.This report provides a detailed overview of key factors in the Online Translation Market and factors such as driver, restraint, past and current trends, regulatory scenarios and technology development. A thorough analysis of these factors has been conducted to determine future growth prospects in the global market.
What is Online Translation?
Online translation refers to machine translation which converts one language into another. With over 6500 languages across the world, it’s humanly impossible for an individual to have a sound understanding of many of them. Online translation solutions coupled with growing digitalization and increasing internet penetration help reducing the problems caused by a language barrier. Considering the rapid growth in the international tourism industry and wide adoption in the education sector, online translation services will continue to grow.
The titled segments and sub-section of the market are illuminated below:
Type (Android, Ios, Windows), Application (Automotive, Military & Defense, Electronics, IT, Healthcare, Others), Technology (RBMT, SMT, Others)
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Online Translation the manufacturing cost structure analysis of the market is based on the core chain structure, engineering process, raw materials and suppliers. The manufacturing plant has been developed for market needs and new technology development. In addition, Online Translation Market attractiveness according to country, end-user, and other measures is also provided, permitting the reader to gauge the most talented or commercial areas for investments. The report also provides a detailed synopsis of the competitive scenario, wherein complete business profiles of some of the prime companies in the market are included.
Geographically World Online Translation markets can be classified as North America, Europe, Asia Pacific (APAC), Middle East and Africa and Latin America. North America has gained a leading position in the global market and is expected to remain in place for years to come. The growing demand for Online Translation markets will drive growth in the North American market over the next few years.
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In the last section of the report, the companies responsible for increasing the sales in the Online Translation Market have been presented. These companies have been analyzed in terms of their manufacturing base, basic information, and competitors. In addition, the application and product type introduced by each of these companies also form a key part of this section of the report. The recent enhancements that took place in the global market and their influence on the future growth of the market have also been presented through this study.
Market Trends:
Adoption of Online Translation and Instant Web Publishing Requirement
Development of Translation Based Apps
Growing Inclination Towards the expansion of Business in Different Regions
E-Learning Courses in Different Language
Market Drivers:
Need For Cost-Effective and Quick Translation Solution
Rising International Tourism and Multilingual World’s Culture
Opportunities:
Digital Transformation and AI-Driven Translation Technology
Emergence of Video Translation Techniques
Challenges:
Lack of Quality Limits Other Uses Apart from Colloquial
Network Issues and System Failure
Strategic Points Covered in Table of Content of Online Translation Market:
Chapter 1: Introduction, market driving force product Objective of Study and Research Scope the Online Translation market
Chapter 2: Exclusive Summary – the basic information of the Online Translation Market.
Chapter 3: Displaying the Market Dynamics- Drivers, Trends and Challenges of the Online Translation
Chapter 4: Presenting the Online Translation Market Factor Analysis Porters Five Forces, Supply/Value Chain, PESTEL analysis, Market Entropy, Patent/Trademark Analysis.
Chapter 5: Displaying the by Type, End User and Region 2013-2018
Chapter 6: Evaluating the leading manufacturers of the Online Translation market which consists of its Competitive Landscape, Peer Group Analysis, BCG Matrix & Company Profile
Chapter 7: To evaluate the market by segments, by countries and by manufacturers with revenue share and sales by key countries in these various regions.
Chapter 8& 9: Displaying the Appendix, Methodology and Data Source
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When exposed to external antigens, T cells are rapidly activated to proliferate and differentiate. A genetic screen identified a mutation called elektra that causes immunodeficiency in mice through a single loss-of-function missense mutation in the Schlafen 2 (Slfn2) gene (1). Slfn2 mutation was associated with impaired T cell activation. However, whether Slfn2 regulates T cell function directly, and how, was unclear. On page 703 of this issue, Yue et al. (2) report that SLFN2 safeguards T cells from excessive stress during activation and thus facilitates the necessary up-regulation of protein translation. SLFN2 binds and shields transfer RNAs (tRNAs), essential adaptor molecules in translation of messenger RNAs (mRNAs), from stress-activated fragmentation. Without SLFN2, excessive tRNA fragmentation lowers global translation and specifically decreases the translation of key cytokine receptor proteins important for T cell activation. This study expands the role of tRNA fragmentation and implicates SLFN2 in preventing fragmentation to enable immune function.
During T cell activation, quiescent T cells turn on cellular machineries to ramp up metabolism, which demands an increase in protein synthesis. SLFN2 is a member of the Schlafen gene family, mostly present in mammals. The family was first identified in 1998 through the screening of regulators for thymocyte development (3). Owing to a lack of homology with other protein families, the functions and mechanisms of action of the Schlafen proteins are still mostly elusive. Yue et al. found that signaling in response to the cytokine interleukin-2 (IL-2) was impaired by Slfn2 deficiency in T cells. IL-2 receptors (IL-2Rs) are expressed on activated T cells, and binding to IL-2 induces gene expression and metabolic programs that are important for T cell activation (4, 5). Expression of IL-2Rβ and IL-2Rγ, but not the IL-2Rα subunit, is decreased, most likely as a result of decreased translation, when Slfn2 is absent. A global proteomics study showed that translation is highly dynamic during T cell activation, with both rapid turnover of select proteins and idling ribosomes poised for new synthesis (6). A similar analysis will clarify which proteins, besides IL-2Rβ and IL-2Rγ, are specifically protected for translation by SLFN2 during T cell activation.
In addition to specific IL-2R proteins, global translation was lowered by Slfn2 deficiency (2). This decrease was observed both in quiescent T cells and after T cell activation. The connection between SLFN2 and translation is perhaps not completely unexpected. Other Schlafen family members, human SLFN11 and SLFN13, can recognize and cleave tRNAs during HIV infection (7, 8). Yue et al. find that SLFN2 also binds tRNA. However, unlike SLFN11 and SLFN13, SLFN2 does not cleave tRNAs because of two missing acidic residues important for the ribonuclease (RNase) activity, but instead shields the tRNAs from cleavage into 30- to 40-nucleotide RNA fragments (tRNAs are 79 to 90 nucleotides).
tRNA fragmentation is known to repress global protein translation, repress translation of specific target mRNAs by microRNA-like action, and regulate mRNA stability. tRNA-derived fragments (tRFs), particularly the subclass that is nearly half a tRNA in size, are often generated upon stress and form stress granules, cytoplasmic RNA-protein complexes that repress global translation by sequestering translation initiation factors (9). What is causing tRNA cleavage during T cell activation? Paradoxically, rapid T cell proliferation is also accompanied by increased concentrations of reactive oxygen species (ROS). ROS arise as by-products from amplified mitochondrial metabolism and activate important transcription factors during T cell activation (10, 11). However, ROS have other downstream effects during T cell activation: tRNA cleavage, translation inhibition, and stress-granule formation. These stress responses are hyperactivated in Slfn2-deficient T cells, despite similar ROS concentrations, suggesting that Slfn2 deficiency exacerbates ROS sensing. The increased stress response and defective proliferation in Slfn2-deficient T cells are counteracted by antioxidant (N-acetylcysteine) treatment. Together, this suggests that increased ROS trigger excessive tRNA cleavage and suppress translation in the absence of SLFN2. Thus, SLFN2 sets the threshold for determining whether T cells should proliferate or be inactivated by the stress response when the cells recognize antigen (see the figure).
Protecting T cells from stress
T cell activation is accompanied by increased amounts of reactive oxygen species (ROS). Schlafen 2 (SLFN2) protects transfer RNAs (tRNAs) from ROS-induced cleavage to maintain the increased translation that is necessary for T cell activation. When SLFN2 is absent, this tRNA protection is removed, and T cells are more sensitive to ROS amounts and thus more likely to undergo cell death.
GRAPHIC: KELLIE HOLOSKI/SCIENCE
Angiogenin (ANG) is a potent RNase that cleaves the tRNA anticodon loop to produce the half-molecule type of tRFs (9). Yue et al. found that SLFN2 protects tRNAs from ANG cleavage, and lower ANG expression restored tRNA amounts, protein translation, and cell proliferation of Slfn2-deficient T cells. Ang mRNA and protein expression are upregulated by T cell activation, which can be reversed by antioxidant. This represents a newly identified mechanism to trigger tRNA cleavage by directly regulating RNase expression. Further investigation is needed to understand whether the tRNA-protective function of SLFN2 also exists in other cell types.
The study by Yue et al. reveals an intricate regulation of ROS sensing and translation by SLFN2 during T cell activation. This mechanism may be relevant in autoimmunity because SLFN2 is important in a mouse model of multiple sclerosis (2). Notably, Schlafen family functions are not completely understood (12). This study opens several future directions in Schlafen family research. Is the regulation of RNA metabolism and translation a common theme of Schlafen function? It is unknown whether Schlafen proteins can bind to (and protect or cleave) other cellular RNAs or viral RNAs. Additionally, whether there is redundancy of function between members of the family awaits further research.
Growing evidence shows that tRNA fragments are not random degradation products, but rather they have biological functions (9). Because tRNA fragmentation can repress translation by decreasing the pool of tRNAs, or through direct inhibitory effects of tRNA fragments on the translation machinery through stress-granule formation or microRNA-like action, it will be interesting to determine which mechanism, if not all, are contributing to translation repression in SLFN2-deficient T cells. Additionally, RNases other than ANG mediate tRNA fragmentation (9), and in other contexts, tRNA fragments are generated efficiently even after Ang deletion (13). This suggests that although Yue et al. characterize ANG as the major tRNase during T cell activation, the mechanism may be generalizable to other RNases, whose activities could be regulated by other SLFN2-like tRNA-protective proteins in other biological contexts or cell lineages.
Acknowledgments: Work in the authors' laboratory is supported by R01 AR067712 from the National Institutes of Health.
