Inst 250 Assignment Discovery

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Significance

Largely overlooked, the viruses of protists have started to attract more attention. Several viruses of the family Totiviridae are currently implicated in the increased pathogenicity of parasitic protozoa such as Leishmania to vertebrate hosts. We conducted a broad survey of RNA viruses within trypanosomatids, one of the iconic groups of protists. These revealed several previously unidentified viral taxa including one designated “Leishbunyaviridae” and a highly divergent virus termed “Leptomonas pyrrhocoris ostravirus 1.” Our studies provide important information on the origins as well as the diversity and distribution of viruses within a group of protists related to the human parasite Leishmania.

Abstract

Knowledge of viral diversity is expanding greatly, but many lineages remain underexplored. We surveyed RNA viruses in 52 cultured monoxenous relatives of the human parasite Leishmania (Crithidia and Leptomonas), as well as plant-infecting Phytomonas. Leptomonas pyrrhocoris was a hotbed for viral discovery, carrying a virus (Leptomonas pyrrhocoris ostravirus 1) with a highly divergent RNA-dependent RNA polymerase missed by conventional BLAST searches, an emergent clade of tombus-like viruses, and an example of viral endogenization. A deep-branching clade of trypanosomatid narnaviruses was found, notable as Leptomonas seymouri bearing Narna-like virus 1 (LepseyNLV1) have been reported in cultures recovered from patients with visceral leishmaniasis. A deep-branching trypanosomatid viral lineage showing strong affinities to bunyaviruses was termed “Leishbunyavirus” (LBV) and judged sufficiently distinct to warrant assignment within a proposed family termed “Leishbunyaviridae.” Numerous relatives of trypanosomatid viruses were found in insect metatranscriptomic surveys, which likely arise from trypanosomatid microbiota. Despite extensive sampling we found no relatives of the totivirus Leishmaniavirus (LRV1/2), implying that it was acquired at about the same time the Leishmania became able to parasitize vertebrates. As viruses were found in over a quarter of isolates tested, many more are likely to be found in the >600 unsurveyed trypanosomatid species. Viral loss was occasionally observed in culture, providing potentially isogenic virus-free lines enabling studies probing the biological role of trypanosomatid viruses. These data shed important insights on the emergence of viruses within an important trypanosomatid clade relevant to human disease.

The ability of viruses to infect virtually any cellular life form on Earth contributes to their immense diversity. While many eukaryotic groups have been probed for the viral presence, the full diversity of viruses remains to be explored (1). Especially promising is the investigation of RNA viruses in simple eukaryotes such as fungi, green algae, diatoms, slime molds, oomycetes, dinoflagellates, apicomplexans, kinetoplastids, diplomonads, and trichomonads (2⇓–4). While originally considered to be little more than evolutionary curiosities, these viruses have started to attract more attention as their important biological roles are now emerging. For example, Cryphonectria hypovirus 1 plays a key role in limiting pathogenicity to its fungal hosts, with applications toward biological control (5), and several viruses of the family Totiviridae have been implicated in the increased pathogenicity of parasitic protozoa to vertebrate hosts (6, 7).

Most studies reporting unicellular eukaryotic viruses arose from fortuitous discovery of virus-like particles (VLPs) or abundant discrete RNA segments rather than from systematic searches often termed “virus hunting.” Here we present a broad survey of RNA viruses within trypanosomatids, one of the iconic groups of protists. Members of the family Trypanosomatidae exhibit strikingly unusual molecular and biochemical traits (8⇓⇓⇓–12). Several species cause widespread severe illnesses, such as sleeping sickness, Chagas disease, and kala-azar in humans (13). Monoxenous (with one host) parasites of invertebrates (primarily insects) were ancestors of these dixenous (with two hosts) pathogens and still represent the majority of trypanosomatid lineages (14, 15). Phylogenetic analysis of the Trypanosomatidae has shown convincingly that the transition from a monoxenous to a dixenous state occurred at least three times, giving rise to the genera Trypanosoma and Leishmania (both parasites of vertebrates), as well as plant-dwelling Phytomonas (16).

VLPs were reported from a number of trypanosomatid species including Endotrypanum schaudinni, Leishmania hertigi [now classified as Paraleishmania hertigi (17)], Phytomonas spp., Crithidia pragensis, Leptomonas seymouri, Angomonas desouzai, and others (18⇓⇓⇓⇓–23). The molecular era in the research of trypanosomatid viruses began with the pioneering studies of those found in South American Leishmania spp. including Leishmania RNA virus 1 (LRV1) from Leishmania guyanensis and Leishmania braziliensis (24, 25), and an unrelated RNA virus in Phytomonas (21). The biological significance of these lays fallow until the finding that LRV1 was associated with increased disease pathology, parasite numbers, and immune response in animal models (6, 26⇓⇓–29). Subsequent studies provided evidence linking LRV1 to the severity of human leishmaniasis, including acute pathology and drug-treatment failures (30⇓⇓–33), although data relating the viral presence to the chronic mucocutaneous leishmaniasis are mixed (32, 34⇓–36).

Recently, molecular descriptions have been made for the viruses from several additional trypanosomatid species. Among them were a bunyavirus-like virus of Leptomonas moramango (37) as well as narnavirus-like viruses of Leptomonas seymouri (38) and the dixenous plant pathogen Phytomonas serpens (39). Provocatively, Leptomonas seymouri has been recovered from cultures from visceral leishmaniasis patients infected with Leishmania donovani, and many of such Leptomonas seymouri strains bear NLV1 (40). Thus, there appears to be considerable unexplored viral diversity in trypanosomatids, the study of which may contribute to our understanding of the biology of trypanosomatids and their insect and/or plant hosts as well as the origins of viruses in Leishmania.

Results and Discussion

Screening of Trypanosomatid Isolates.

We surveyed 52 isolates including 44 belonging to the genera Crithidia and Leptomonas (subfamily Leishmaniinae), as well as eight belonging to Phytomonas spp. These originated from diverse insect or plant hosts and geographic regions (Table S1). Total RNA from these isolates was digested with S1 nuclease, removing most cellular RNAs, after which the remaining dsRNA arising from dsRNA viruses or replicative intermediates of ssRNA viruses could then be sensitively detected by gel electrophoresis (see Figs. 1A, 3A, and 4A) (41). From this analysis, 11 Leishmaniinae and three Phytomonas spp. exhibited dsRNA bands, while the remainder appeared to lack them (Table 1). Most RNA segments were sequenced, and the sequences of those encoding viral RNA-dependent RNA polymerase (RDRP) were used to assign affiliations to the known viral families.

Fig. 1.

Tombus-like virus from Leptomonas pyrrhocoris. (A) Agarose gel electrophoresis of S1-digested total RNAs from strains H10 (lane 1), F19 (lane 2), and F165 (lane 3). LeppyrTLV1 segments are labeled “RNA-T1” and “RNA-T2” on the right and marked by green dots; LeppyrOV1 segments are marked by red dots. The left lane shows a 1-kb DNA ladder. (B) Genome structure of LeppyrTLV1. ORFs for different predicted proteins are shown in different colors. A 127-nt stem-loop is found within the predicted N-terminal region of ORF2. (C) Sequence of the ORF1/2 overlap region including a putative slippery sequence (yellow). The RDRP domain is predicted to start from the ACC coding for threonine as previously reported for the UUUUUA slippery sequence (43). (D) Maximum likelihood phylogenetic tree based on RDRP amino acid sequences. Host taxa are shown by symbols defined in the key for hosts. Numbers at the branches indicate Bayesian posterior probability and maximum likelihood bootstrap supports, respectively; those having a Bayesian posterior probability value of 1.0 and maximum likelihood bootstrap support of 100% are marked with black circles. (The scale bar indicates the number of substitutions per site.) The tree was rooted with the sequences of Nodaviridae. Abbreviations and GenBank accession numbers are given in Tables S2–S4.

Table 1.

Virus-positive trypanosomatid isolates

RNA Viruses of Leptomonas pyrrhocoris.

Three of 18 isolates of Leptomonas pyrrhocoris (H10, F165, and F19) originating from various locations worldwide (42) exhibited viral dsRNA bands (Table S1). All three bore two common RNAs of 3.5 and 2.2 kb, termed “RNA-T1” and “RNA-T2” (marked by green dots in Fig. 1A), and two (H10 and F19) contained six additional bands termed “RNAs O1–O6” (marked by red dots in Fig. 1A). Sequence analysis of all RNA segments from H10 and F165 suggested the presence of two viruses. The first was distantly related to Tombusviridae. It comprised RNAs T1 and T2 and was named “Leptomonas pyrrhocoris tombus-like virus 1” (hereafter, “LeppyrTLV1”). The second virus comprising RNAs O1–O6 could not be associated with any of known viral groups and was named “Leptomonas pyrrhocoris ostravirus 1” after the city of Ostrava, where it was discovered (hereafter “LeppyrOV1”). PCR tests confirmed the presence/absence of assignments made by S1 nuclease analysis (Table 1).

LeppyrTLV1.

The sequences of segments T1 and T2 in the strains H10 and F165 were highly similar (96.7 and 97.05% nucleotide identity, respectively). RNA-T1 contained two overlapping ORFs with predicted proteins of 850 and 515 aa (Fig. 1 B and C). For ORF1, a BLAST search in the National Center for Biotechnology Information (NCBI) nonredundant protein database did not yield any hits. The ORF2 showed a clear homology to viral RDRP (cd01699 in the NCBI Conserved Domain Database, CDD) with closest relationships to positive-strand RNA viruses of the Tombusviridae/Nodaviridae group (1). The two ORFs showed an overlap of 880 nt (Fig. 1C). A putative slippery sequence, UUUUUUA, was found 6 nt into the overlap, followed by a 127-nt hairpin 6 nt further. Both elements are typical of the −1 ribosomal frameshift of various viruses (43⇓–45). These data suggest that the RDRP of this virus arises through the synthesis of an N-terminal frameshifted protein. While typical Tombusviridae encode RDRPs translated as a C-terminal extension of an upstream ORF by stop-codon read-through (46), several examples of −1 ribosomal frameshifting have been reported recently (1, 47, 48). RNA-T2 encoded a single ORF (ORF3) with a predicted protein of 455 aa (Fig. 1B), for which no homologs were identified in BLAST database searches.

Neither RNA T1 nor T2 exhibited conserved terminal sequences, which are also absent in both Tombusviridae and Nodaviridae (49, 50). Typically tombusviruses are monopartite, and the members of the related family Nodaviridae have two segments (49, 51). However, recent studies have shown remarkable variation within both groups (1).

Phylogenetic reconstruction using RDRP sequences placed LeppyrTLV1 within a clade distantly related to Tombusviridae, which usually infect plants (Fig. 1D). This clade includes viruses from invertebrates including parasitic nematodes, terrestrial myriapods, bivalves, cephalopods, freshwater crustaceans, and gastropods (Fig. 1D and Table S2) (1). Pyrrhocoris apterus, the firebug host of Leptomonas pyrrhocoris, is known to feed on the corpses of invertebrates (52), suggesting this as a possible route of acquisition.

Endogenous viral element related to LeppyrTLV1.

BLAST searches against the genome assembly of Leptomonas pyrrhocoris H10 (53) revealed that the ORF H10_02_0010 at the rightmost end of the chromosome 2 is homologous to the LeppyrTLV1 RDRP (Fig. S1A). Similar to the RNA-T1 of LeppyrTLV1, an overlapping ORF, H10_02_0020, was found immediately upstream. The overlap contained a potential slippery sequence, GGGAAAU, although we did not detect a stem-loop element thereafter (Fig. S1). The ORF H10_02_0010 and the LeppyrTLV1 RDRP shared 38% overall amino acid identity, including conservation of key RDRP motifs (Fig. S1D). Whole-transcriptome data for Leptomonas pyrrhocoris (53) confirmed transcription of both ORFs. No homology was detected between the ORF1 of LeppyrTLV1 and the predicted chromosomal protein H10_02_0020. We considered the two ORFs of the chromosome 2 as an endogenous viral element (EVE) related to LeppyrTLV1 and named it “LeppyrTLV-EVE1.”

PCR tests with primers specific to LeppyrTLV-EVE1 RDRP revealed its presence in four additional European isolates (P59, LP, PP1, and PP2), all of whose sequences were identical (Tables S3 and S4). In contrast, this EVE1 region differed by 180 nt substitutions (and 84 indels) from the corresponding part of the LeppyrTLV1 RDRP, while the TLV1 RDRP sequences of strains H10 and F165 differed by only seven nucleotide substitutions. The similarity between EVE1 and TLV1 suggests that a TLV1-like RNA was captured via reverse transcription and integration into the Leptomonas pyrrhocoris genome. EVEs occur frequently in evolution and are thought to be mediated primarily by reverse transcriptases encoded in host retroposons (54⇓–56). Indeed, a number of telomere-associated transposable element (TATE) and spliced leader-associated (SLAC) retroelements have been identified in the Leptomonas pyrrhocoris genome (53), including one located immediately upstream of the LeppyrTLV-EVE1 (Fig. S1A). The high level of sequence divergence with LeppyrTLV1 points to a relatively ancient origin of EVE1, perhaps predating the dispersal of Leptomonas pyrrhocoris across Europe (42).

LeppyrOV1.

The six RNAs O1–O6 of strains H10 and F19 (Fig. 1A) were initially viewed as “satellite” RNAs of LeppyrTLV1. However, several observations suggested that they comprise separate virus. First, unlike TLV1 RNAs T1 and T2, the termini of RNAs O1–O6 share common sequences: AAAGAAAAAA at the 5′ and ATGAGTTT at the 3′ ends (defined in the presumptive protein-coding strand orientation) (Fig. 2A). Conserved terminal sequences are known to participate in the replication of viruses and often are defining features of viral families (57). Second, in all strains the ratio of RNAs T1 to T2 was relatively constant; the same was true for RNAs O1–O6. However, the overall ratio of both RNA groups was substantially different.

Fig. 2.

Leptomonas pyrrhocoris ostravirus 1, a unique virus from Leptomonas pyrrhocoris. (A) Genome structure of LeppyrOV1, showing shared terminal sequences and a single ORF per segment (squiggle marks an incompletely sequenced end). The location of an RDRP domain predicted on RNA-O3 by CDD search, PHYRE2, and HHPred software is shown. (B) Multiple alignments of the LeppyrOV1 putative RDRP with those of Picorna-, Flavi-, and Caliciviridae. Identical residues are shown in red; similar residues are shown in blue. Amino acid motifs, typically found in viral RDRPs, are highlighted in yellow.

Segments O1–O6 each contained a single ORF, and conventional BLAST searches did not yield any homologs for the corresponding hypothetical proteins. However, search algorithms focused on both structural and sequence homology revealed a putative RDRP motif within the predicted 1,315-aa protein within segment O3 (Fig. 2A), albeit with modest statistical support (NCBI CDD, amino acids 767–870, e = 0.89; PHYRE 2, amino acids 684–874, confidence = 56%; HHPRED, amino acids 693–874, confidence = 89.7%) (58, 59). Within this region we identified conserved viral RDRP motifs responsible for catalytic activity and ribonucleotide selectivity (Fig. 2B) (60⇓–62). Analysis of the base frequencies of codon third positions of the viral ORFs showed significant differences between TLV1 and OV1 and a greater degree between these and the nuclear genome of Leptomonas pyrrhocoris (Table S5).

Thus, we conclude that RNAs O1–O6 comprise a previously undescribed virus, Leptomonas pyrrhocoris ostravirus 1 (LeppyrOV1). As yet, we have not found a trypanosomatid strain containing this virus alone, which would firmly establish its independence from LeppyrTLV1. Further studies are required to address the functional relationships between the six segments of this virus and significance of its co-occurrence with LeppyrTLV1.

A Bunyavirus-Like Genus, “Leishbunyavirus.”

Six isolates showed the presence of dsRNAs related to previously described viruses of Leptomonas moramango (37). LepmorLBV1a and b showed features characteristic of many other bunyaviruses, including a trisegmented genome, terminal “panhandle” repeats, and sequence relatedness of the predicted RDRP and nucleocapsid proteins, and were thus assigned as species within the genus Leishbunyavirus (LBV) (37). We confirmed the presence of LepmorLBV1a and 1b in Leptomonas moramango, as well as LBV1s in the dixenous phytopathogenic Phytomonas sp. TCC231 (PTCCLBV1) and four species of Crithidia: Crithidia otongatchiensis (CotoLBV1), Crithidia abscondita (CabsLBV1), Crithidia sp. G15 (CG15LBV1), and Crithidia sp. ZM (CZMLBV1) (Fig. 3A and Table 1). PCR tests with primers complementary to the conserved regions of LBV1 RDRPs showed the presence of these viruses in Crithidia sp. C4 and Crithidia pragensis as well (Table 1). These LBV1-positive strains showed three dsRNAs, except PTCCLBV1 which exhibited only two (Table 1). We sequenced all segments of CotoLBV1 and CabsLBV1 and the largest segment (completely or partially) of the others (Table 1 and Tables S3 and S4).

"MIT" redirects here. For other uses, see MIT (disambiguation).

MottoMens et Manus (Latin)

Motto in English

Mind and Hand[1]
TypePrivate
Land grant
Space grant
EstablishedApril 10, 1861 (1861-04-10)

Academic affiliations

AAU
AICUM
AITU
APLU
COFHE
NAICU[2]
URA
568 Group
Endowment$14.8 billion (2017)[3]
ChancellorCynthia Barnhart
PresidentL. Rafael Reif
ProvostMartin A. Schmidt

Academic staff

1,021[4]
Students11,319[5]
Undergraduates4,512[5]
Postgraduates6,807
LocationCambridge, Massachusetts, U.S.
CampusUrban, 168 acres (68.0 ha)[6]
NewspaperThe Tech
ColorsCardinal Red and Silver Gray[7]
         
NicknameEngineers[8]

Sporting affiliations

NCAA Division III – NEWMAC, NEFC,
Pilgrim League
Division I – EARC and EAWRC(rowing)
MascotTim the Beaver[9]
Websiteweb.mit.edu

The Massachusetts Institute of Technology (MIT) is a privateresearch university in Cambridge, Massachusetts, United States. Founded in 1861 in response to the increasing industrialization of the United States, MIT adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. The Institute is traditionally known for its research and education in the physical sciences and engineering, but more recently in biology, economics, linguistics and management as well. MIT is often cited among the world's best universities by various organizations.[10][11][12][13][14] It was ranked as the world's top university for 6 years in a row by QS.[15]

As of 2017[update], 88 Nobel laureates, 52 National Medal of Science recipients, 65 Marshall Scholars, 45 Rhodes Scholars, 38 MacArthur Fellows, 34 astronauts, 21 Turing award winners, 16 Chief Scientists of the U.S. Air Force and 6 Fields Medalists have been affiliated with MIT. The school has a strong entrepreneurial culture and the aggregated revenues of companies founded by MIT alumni would rank as the eleventh-largest economy in the world.[16][17] MIT is a member of the Association of American Universities (AAU).

History[edit]

Main article: History of the Massachusetts Institute of Technology

Foundation and vision[edit]

[...] a school of industrial science aiding the advancement, development and practical application of science in connection with arts, agriculture, manufactures, and commerce.
— Act to Incorporate the Massachusetts Institute of Technology,
Acts of 1861, Chapter 183[18]

In 1859, a proposal was submitted to the Massachusetts General Court to use newly filled lands in Back Bay, Boston for a "Conservatory of Art and Science", but the proposal failed.[19][20] A charter for the incorporation of the Massachusetts Institute of Technology, proposed by William Barton Rogers, was signed by the governor of Massachusetts on April 10, 1861.[21]

Rogers, a professor from the University of Virginia, wanted to establish an institution to address rapid scientific and technological advances.[22][23] He did not wish to found a professional school, but a combination with elements of both professional and liberal education,[24] proposing that:

The true and only practicable object of a polytechnic school is, as I conceive, the teaching, not of the minute details and manipulations of the arts, which can be done only in the workshop, but the inculcation of those scientific principles which form the basis and explanation of them, and along with this, a full and methodical review of all their leading processes and operations in connection with physical laws.[25]

The Rogers Plan reflected the German research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars and laboratories.[26][27]

Early developments[edit]

Two days after MIT was chartered, the first battle of the Civil War broke out. After a long delay through the war years, MIT's first classes were held in the Mercantile Building in Boston in 1865.[28] The new institute was founded as part of the Morrill Land-Grant Colleges Act to fund institutions "to promote the liberal and practical education of the industrial classes" and was a land-grant school.[29][30] In 1863 under the same act, the Commonwealth of Massachusetts founded the Massachusetts Agricultural College, which developed as the University of Massachusetts Amherst. In 1866, the proceeds from land sales went toward new buildings in the Back Bay.[31]

MIT was informally called "Boston Tech".[31] The institute adopted the European polytechnic university model and emphasized laboratory instruction from an early date.[32] Despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under President Francis Amasa Walker.[33] Programs in electrical, chemical, marine, and sanitary engineering were introduced,[34][35] new buildings were built, and the size of the student body increased to more than one thousand.[33]

The curriculum drifted to a vocational emphasis, with less focus on theoretical science.[36] The fledgling school still suffered from chronic financial shortages which diverted the attention of the MIT leadership. During these "Boston Tech" years, MIT faculty and alumni rebuffed Harvard University president (and former MIT faculty) Charles W. Eliot's repeated attempts to merge MIT with Harvard College's Lawrence Scientific School.[37] There would be at least six attempts to absorb MIT into Harvard.[38] In its cramped Back Bay location, MIT could not afford to expand its overcrowded facilities, driving a desperate search for a new campus and funding. Eventually the MIT Corporation approved a formal agreement to merge with Harvard, over the vehement objections of MIT faculty, students, and alumni.[38] However, a 1917 decision by the Massachusetts Supreme Judicial Court effectively put an end to the merger scheme.[38]

In 1916, the MIT administration and the MIT charter crossed the Charles River on the ceremonial barge Bucentaur built for the occasion,[39][40] to signify MIT's move to a spacious new campus largely consisting of filled land on a mile-long tract along the Cambridge side of the Charles River.[41][42] The neoclassical "New Technology" campus was designed by William W. Bosworth[43] and had been funded largely by anonymous donations from a mysterious "Mr. Smith", starting in 1912. In January 1920, the donor was revealed to be the industrialist George Eastman of Rochester, New York, who had invented methods of film production and processing, and founded Eastman Kodak. Between 1912 and 1920, Eastman donated $20 million ($236.6 million in 2015 dollars) in cash and Kodak stock to MIT.[44]

Curricular reforms[edit]

In the 1930s, President Karl Taylor Compton and Vice-President (effectively Provost) Vannevar Bush emphasized the importance of pure sciences like physics and chemistry and reduced the vocational practice required in shops and drafting studios.[45] The Compton reforms "renewed confidence in the ability of the Institute to develop leadership in science as well as in engineering".[46] Unlike Ivy League schools, MIT catered more to middle-class families, and depended more on tuition than on endowments or grants for its funding.[47] The school was elected to the Association of American Universities in 1934.[48]

Still, as late as 1949, the Lewis Committee lamented in its report on the state of education at MIT that "the Institute is widely conceived as basically a vocational school", a "partly unjustified" perception the committee sought to change. The report comprehensively reviewed the undergraduate curriculum, recommended offering a broader education, and warned against letting engineering and government-sponsored research detract from the sciences and humanities.[49][50] The School of Humanities, Arts, and Social Sciences and the MIT Sloan School of Management were formed in 1950 to compete with the powerful Schools of Science and Engineering. Previously marginalized faculties in the areas of economics, management, political science, and linguistics emerged into cohesive and assertive departments by attracting respected professors and launching competitive graduate programs.[51][52] The School of Humanities, Arts, and Social Sciences continued to develop under the successive terms of the more humanistically oriented presidents Howard W. Johnson and Jerome Wiesner between 1966 and 1980.[53]

Defense research[edit]

MIT's involvement in military science surged during World War II. In 1941, Vannevar Bush was appointed head of the federal Office of Scientific Research and Development and directed funding to only a select group of universities, including MIT.[54] Engineers and scientists from across the country gathered at MIT's Radiation Laboratory, established in 1940 to assist the British military in developing microwaveradar. The work done there significantly affected both the war and subsequent research in the area.[55] Other defense projects included gyroscope-based and other complex control systems for gunsight, bombsight, and inertial navigation under Charles Stark Draper's Instrumentation Laboratory;[56][57] the development of a digital computer for flight simulations under Project Whirlwind;[58] and high-speed and high-altitude photography under Harold Edgerton.[59][60] By the end of the war, MIT became the nation's largest wartime R&D contractor (attracting some criticism of Bush),[54] employing nearly 4000 in the Radiation Laboratory alone[55] and receiving in excess of $100 million ($1.2 billion in 2015 dollars) before 1946.[46] Work on defense projects continued even after then. Post-war government-sponsored research at MIT included SAGE and guidance systems for ballistic missiles and Project Apollo.[61]

...a special type of educational institution which can be defined as a university polarized around science, engineering, and the arts. We might call it a university limited in its objectives but unlimited in the breadth and the thoroughness with which it pursues these objectives.
— MIT president James Rhyne Killian, 1949[62]

These activities affected MIT profoundly. A 1949 report noted the lack of "any great slackening in the pace of life at the Institute" to match the return to peacetime, remembering the "academic tranquility of the prewar years", though acknowledging the significant contributions of military research to the increased emphasis on graduate education and rapid growth of personnel and facilities.[63] The faculty doubled and the graduate student body quintupled during the terms of Karl Taylor Compton, president of MIT between 1930 and 1948; James Rhyne Killian, president from 1948 to 1957; and Julius Adams Stratton, chancellor from 1952 to 1957, whose institution-building strategies shaped the expanding university. By the 1950s, MIT no longer simply benefited the industries with which it had worked for three decades, and it had developed closer working relationships with new patrons, philanthropic foundations and the federal government.[64]

In late 1960s and early 1970s, student and faculty activists protested against the Vietnam War and MIT's defense research.[65][66] In this period MIT's various departments were researching helicopters, smart bombs and counterinsurgency techniques for the war in Vietnam as well as guidance systems for nuclear missiles.[67] The Union of Concerned Scientists was founded on March 4, 1969 during a meeting of faculty members and students seeking to shift the emphasis on military research toward environmental and social problems.[68] MIT ultimately divested itself from the Instrumentation Laboratory and moved all classified research off-campus to the MIT Lincoln Laboratory facility in 1973 in response to the protests.[69][70] The student body, faculty, and administration remained comparatively unpolarized during what was a tumultuous time for many other universities.[65] Johnson was seen to be highly successful in leading his institution to "greater strength and unity" after these times of turmoil.[71] However six MIT students were sentenced to prison terms at this time and some former student leaders, such as Michael Albert and George Katsiaficas, are still indignant about MIT's role in military research and its suppression of these protests.[72] (Richard Leacock's film, November Actions, records some of these tumultuous events.[73])

In the 1980s, there was more controversy at MIT over its involvement in SDI (space weaponry) and CBW (chemical and biological warfare) research.[74] More recently, MIT’s research for the military has included work on robots, drones and ‘battle suits’.[75]

Recent history[edit]

MIT has kept pace with and helped to advance the digital age. In addition to developing the predecessors to modern computing and networking technologies,[76][77] students, staff, and faculty members at Project MAC, the Artificial Intelligence Laboratory, and the Tech Model Railroad Club wrote some of the earliest interactive computer video games like Spacewar! and created much of modern hackerslang and culture.[78] Several major computer-related organizations have originated at MIT since the 1980s: Richard Stallman's GNU Project and the subsequent Free Software Foundation were founded in the mid-1980s at the AI Lab; the MIT Media Lab was founded in 1985 by Nicholas Negroponte and Jerome Wiesner to promote research into novel uses of computer technology;[79] the World Wide Web Consortiumstandards organization was founded at the Laboratory for Computer Science in 1994 by Tim Berners-Lee;[80] the OpenCourseWare project has made course materials for over 2,000 MIT classes available online free of charge since 2002;[81] and the One Laptop per Child initiative to expand computer education and connectivity to children worldwide was launched in 2005.[82]

MIT was named a sea-grant college in 1976 to support its programs in oceanography and marine sciences and was named a space-grant college in 1989 to support its aeronautics and astronautics programs.[83][84] Despite diminishing government financial support over the past quarter century, MIT launched several successful development campaigns to significantly expand the campus: new dormitories and athletics buildings on west campus; the Tang Center for Management Education; several buildings in the northeast corner of campus supporting research into biology, brain and cognitive sciences, genomics, biotechnology, and cancer research; and a number of new "backlot" buildings on Vassar Street including the Stata Center.[85] Construction on campus in the 2000s included expansions of the Media Lab, the Sloan School's eastern campus, and graduate residences in the northwest.[86][87] In 2006, President Hockfield launched the MIT Energy Research Council to investigate the interdisciplinary challenges posed by increasing global energy consumption.[88]

In 2001, inspired by the open source and open access movements,[89] MIT launched OpenCourseWare to make the lecture notes, problem sets, syllabi, exams, and lectures from the great majority of its courses available online for no charge, though without any formal accreditation for coursework completed.[90] While the cost of supporting and hosting the project is high,[91] OCW expanded in 2005 to include other universities as a part of the OpenCourseWare Consortium, which currently includes more than 250 academic institutions with content available in at least six languages.[92] In 2011, MIT announced it would offer formal certification (but not credits or degrees) to online participants completing coursework in its "MITx" program, for a modest fee.[93] The "edX" online platform supporting MITx was initially developed in partnership with Harvard and its analogous "Harvardx" initiative. The courseware platform is open source, and other universities have already joined and added their own course content.[94]

Three days after the Boston Marathon bombing of April 2013, MIT Police patrol officer Sean Collier was fatally shot by the suspects Dzhokhar and Tamerlan Tsarnaev, setting off a violent manhunt that shut down the campus and much of the Boston metropolitan area for a day.[95] One week later, Collier's memorial service was attended by more than 10,000 people, in a ceremony hosted by the MIT community with thousands of police officers from the New England region and Canada.[96][97][98] On November 25, 2013, MIT announced the creation of the Collier Medal, to be awarded annually to "an individual or group that embodies the character and qualities that Officer Collier exhibited as a member of the MIT community and in all aspects of his life". The announcement further stated that "Future recipients of the award will include those whose contributions exceed the boundaries of their profession, those who have contributed to building bridges across the community, and those who consistently and selflessly perform acts of kindness".[99][100][101]

In September 2017, the school announced the creation of an artificial intelligence research lab called the MIT-IBM Watson AI Lab. IBM will spend $240 million over the next decade and the lab will be staffed by MIT and IBM scientists.[102]

Campus[edit]

Main article: Campus of the Massachusetts Institute of Technology

MIT's 168-acre (68.0 ha) campus in the city of Cambridge spans approximately a mile along the north side of the Charles River basin.[6] The campus is divided roughly in half by Massachusetts Avenue, with most dormitories and student life facilities to the west and most academic buildings to the east. The bridge closest to MIT is the Harvard Bridge, which is known for being marked off in a non-standard unit of length – the smoot.[103][104]

The KendallMBTA Red Line station is located on the northeastern edge of the campus, in Kendall Square. The Cambridge neighborhoods surrounding MIT are a mixture of high tech companies occupying both modern office and rehabilitated industrial buildings, as well as socio-economically diverse residential neighborhoods.[105][106] In early 2016, MIT presented its updated Kendall Square Initiative to the City of Cambridge, with plans for mixed-use educational, retail, residential, startup incubator, and office space in a dense high-rise transit-oriented development plan.[107][108] The MIT Museum will eventually be moved immediately adjacent to a Kendall Square subway entrance, joining the List Visual Arts Center on the eastern end of the campus.[108][109]

Each building at MIT has a number (possibly preceded by a W, N, E, or NW) designation and most have a name as well. Typically, academic and office buildings are referred to primarily by number while residence halls are referred to by name. The organization of building numbers roughly corresponds to the order in which the buildings were built and their location relative (north, west, and east) to the original center cluster of Maclaurin buildings.[110] Many of the buildings are connected above ground as well as through an extensive network of underground tunnels, providing protection from the Cambridge weather as well as a venue for roof and tunnel hacking.[111][112]

MIT's on-campus nuclear reactor[113] is one of the most powerful university-based nuclear reactors in the United States. The prominence of the reactor's containment building in a densely populated area has been controversial,[114] but MIT maintains that it is well-secured.[115] In 1999 Bill Gates donated US$20 million to MIT for the construction of a computer laboratory named the "William H. Gates Building", and designed by architect Frank Gehry. While Microsoft had previously given financial support to the institution, this was the first personal donation received from Gates.[116]

Other notable campus facilities include a pressurized wind tunnel for testing aerodynamic research and a towing tank for testing ship and ocean structure designs.[117][118] MIT's campus-wide wireless network was completed in the fall of 2005 and consists of nearly 3,000 access points covering 9,400,000 square feet (870,000 m2) of campus.[119]

In 2001, the Environmental Protection Agency sued MIT for violating the Clean Water Act and the Clean Air Act with regard to its hazardous waste storage and disposal procedures.[120] MIT settled the suit by paying a $155,000 fine and launching three environmental projects.[121] In connection with capital campaigns to expand the campus, the Institute has also extensively renovated existing buildings to improve their energy efficiency. MIT has also taken steps to reduce its environmental impact by running alternative fuel campus shuttles, subsidizing public transportation passes, and building a low-emission cogeneration plant that serves most of the campus electricity, heating, and cooling requirements.[122]

The MIT Police with state and local authorities, in the 2009-2011 period, have investigated reports of 12 forcible sex offenses, 6 robberies, 3 aggravated assaults, 164 burglaries, 1 case of arson, and 4 cases of motor vehicle theft on campus; affecting a community of around 22,000 students and employees.[123]

MIT has substantial commercial real estate holdings in Cambridge on which it pays property taxes, plus an additional voluntary payment in lieu of taxes (PILOT) on academic buildings which are legally tax-exempt. As of 2017[update], it is the largest taxpayer in the city, contributing approximately 14% of the city's annual revenues.[124] Holdings include Technology Square, parts of Kendall Square, and many properties in Cambridgeport and Area 4 neighboring the educational buildings.[125] The land is held for investment purposes and potential long-term expansion.

Architecture[edit]

MIT's School of Architecture, now the School of Architecture and Planning, was the first in the United States,[126] and it has a history of commissioning progressive buildings.[127][128] The first buildings constructed on the Cambridge campus, completed in 1916, are sometimes called the "Maclaurin buildings" after Institute president Richard Maclaurin who oversaw their construction. Designed by William Welles Bosworth, these imposing buildings were built of reinforced concrete, a first for a non-industrial – much less university – building in the U.S.[129] Bosworth's design was influenced by the City Beautiful Movement of the early 1900s[129] and features the Pantheon-esque Great Dome housing the Barker Engineering Library. The Great Dome overlooks Killian Court, where graduation ceremonies are held each year. The friezes of the limestone-clad buildings around Killian Court are engraved with the names of important scientists and philosophers.[a] The spacious Building 7 atrium at 77 Massachusetts Avenue is regarded as the entrance to the Infinite Corridor and the rest of the campus.[106]

Alvar Aalto's Baker House (1947), Eero Saarinen's MIT Chapel and Kresge Auditorium (1955), and I.M. Pei's Green, Dreyfus, Landau, and Wiesner buildings represent high forms of post-war modernist architecture.[132][133][134] More recent buildings like Frank Gehry's Stata Center (2004), Steven Holl's Simmons Hall (2002), Charles Correa's Building 46 (2005), and Fumihiko Maki's Media Lab Extension (2009) stand out among the Boston area's classical architecture and serve as examples of contemporary campus "starchitecture".[127][135] These buildings have not always been well received;[136][137] in 2010, The Princeton Review included MIT in a list of twenty schools whose campuses are "tiny, unsightly, or both".[138]

Housing[edit]

Main article: Housing at the Massachusetts Institute of Technology

Undergraduates are guaranteed four-year housing in one of MIT's 12 undergraduate dormitories.[139] Those living on campus can receive support and mentoring from live-in graduate student tutors, resident advisors, and faculty housemasters.[140] Because housing assignments are made based on the preferences of the students themselves, diverse social atmospheres can be sustained in different living groups; for example, according to the Yale Daily News staff's The Insider's Guide to the Colleges, 2010, "The split between East Campus and West Campus is a significant characteristic of MIT. East Campus has gained a reputation as a thriving counterculture."[141] MIT also has 5 dormitories for single graduate students and 2 apartment buildings on campus for married student families.[142]

MIT has an active Greek and co-op housing system, including thirty-six fraternities, sororities, and independent living groups (FSILGs).[143] As of 2015[update], 98% of all undergraduates lived in MIT-affiliated housing; 54% of the men participated in fraternities and 20% of the women were involved in sororities.[144] Most FSILGs are located across the river in Back Bay near where MIT was founded, and there is also a cluster of fraternities on MIT's West Campus that face the Charles River Basin.[145] After the 1997 alcohol-related death of Scott Krueger, a new pledge at the Phi Gamma Delta fraternity, MIT required all freshmen to live in the dormitory system starting in 2002.[146] Because FSILGs had previously housed as many as 300 freshmen off-campus, the new policy could not be implemented until Simmons Hall opened in that year.[147] Recently, MIT has also shut down Senior House. Last year, MIT administrators released data showing just 60 percent of Senior House residents graduated in four years. Campus-wide, the four-year graduation rate is 84 percent.[148]

Organization and administration[edit]

MIT is chartered as a non-profit organization and is owned and governed by a privately appointed board of trustees known as the MIT Corporation.[149] The current board consists of 43 members elected to five-year terms,[150] 25 life members who vote until their 75th birthday,[151] 3 elected officers (President, Treasurer, and Secretary),[152] and 4 ex officio members (the president of the alumni association, the Governor of Massachusetts, the Massachusetts Secretary of Education, and the Chief Justice of the Massachusetts Supreme Judicial Court).[153][154] The board is chaired by Robert Millard, a co-founder of L-3 Communications Holdings.[155][156] The Corporation approves the budget, new programs, degrees and faculty appointments, and elects the President to serve as the chief executive officer of the university and preside over the Institute's faculty.[106][157] MIT's endowment and other financial assets are managed through a subsidiary called MIT Investment Management Company (MITIMCo).[158] Valued at $13.182 billion in 2016, MIT's endowment is the sixth-largest among American colleges and universities.[3]

MIT has five schools (Science, Engineering, Architecture and Planning, Management, and Humanities, Arts, and Social Sciences) and one college (Whitaker College of Health Sciences and Technology), but no schools of law or medicine.[159][b] While faculty committees assert substantial control over many areas of MIT's curriculum, research, student life, and administrative affairs,[161] the chair of each of MIT's 32 academic departments reports to the dean of that department's school, who in turn reports to the Provost under the President.[162] The current president is L. Rafael Reif, who formerly served as provost under President Susan Hockfield, the first woman to hold the post.[163][164]

Academics[edit]

MIT is a large, highly residential, research university with a majority of enrollments in graduate and professional programs.[165] The university has been accredited by the New England Association of Schools and Colleges since 1929.[166][167] MIT operates on a 4–1–4 academic calendar with the fall semester beginning after Labor Day and ending in mid-December, a 4-week "Independent Activities Period" in the month of January, and the spring semester commencing in early February and ceasing in late May.[168]

MIT students refer to both their majors and classes using numbers or acronyms alone.[169] Departments and their corresponding majors are numbered in the approximate order of their foundation; for example, Civil and Environmental Engineering is Course 1, while Linguistics and Philosophy is Course 24.[170] Students majoring in Electrical Engineering and Computer Science (EECS), the most popular department, collectively identify themselves as "Course 6". MIT students use a combination of the department's course number and the number assigned to the class to identify their subjects; for instance, the introductory calculus-based classical mechanics course is simply "8.01" at MIT.[171][c]

Undergraduate program[edit]

The four-year, full-time undergraduate program maintains a balance between professional majors and those in the arts and sciences, and has been dubbed "most selective" by U.S. News,[174] admitting few transfer students[165] and 8.0% of its applicants in the 2015 admissions cycle.[175] MIT offers 44 undergraduate degrees across its five schools.[176] In the 2010–2011 academic year, 1,161 bachelor of science degrees (abbreviated "SB") were granted, the only type of undergraduate degree MIT now awards.[needs update][177][178] In the 2011 fall term, among students who had designated a major, the School of Engineering was the most popular division, enrolling 63% of students in its 19 degree programs, followed by the School of Science (29%), School of Humanities, Arts, & Social Sciences (3.7%), Sloan School of Management (3.3%), and School of Architecture and Planning (2%).[needs update] The largest undergraduate degree programs were in Electrical Engineering and Computer Science (Course 6–2), Computer Science and Engineering (Course 6–3), Mechanical Engineering (Course 2), Physics (Course 8), and Mathematics (Course 18).[172]

All undergraduates are required to complete a core curriculum called the General Institute Requirements (GIRs).[179] The Science Requirement, generally completed during freshman year as prerequisites for classes in science and engineering majors, comprises two semesters of physics, two semesters of calculus, one semester of chemistry, and one semester of biology. There is a Laboratory Requirement, usually satisfied by an appropriate class in a course major. The Humanities, Arts, and Social Sciences (HASS) Requirement consists of eight semesters of classes in the humanities, arts, and social sciences, including at least one semester from each division as well as the courses required for a designated concentration in a HASS division. Under the Communication Requirement, two of the HASS classes, plus two of the classes taken in the designated major must be "communication-intensive",[180] including "substantial instruction and practice in oral presentation".[181] Finally, all students are required to complete a swimming test;[182] non-varsity athletes must also take four quarters of physical education classes.[179]

Most classes rely on a combination of lectures, recitations led by associate professors or graduate students, weekly problem sets ("p-sets"), and periodic quizzes or tests. While the pace and difficulty of MIT coursework has been compared to "drinking from a fire hose",[183][184] the freshmen retention rate at MIT is similar to other research universities.[174] The "pass/no-record" grading system relieves some pressure for first-year undergraduates. For each class taken in the fall term, freshmen transcripts will either report only that the class was passed, or otherwise not have any record of it. In the spring term, passing grades (A, B, C) appear on the transcript while non-passing grades are again not recorded.[185] (Grading had previously been "pass/no record" all freshman year, but was amended for the Class of 2006 to prevent students from gaming the system by completing required major classes in their freshman year.[186]) Also, freshmen may choose to join alternative learning communities, such as Experimental Study Group, Concourse, or Terrascope.[185]

In 1969, Margaret MacVicar founded the Undergraduate Research Opportunities Program (UROP) to enable undergraduates to collaborate directly with faculty members and researchers. Students join or initiate research projects ("UROPs") for academic credit, pay, or on a volunteer basis through postings on the UROP website or by contacting faculty members directly.[187] A substantial majority of undergraduates participate.[188][189] Students often become published, file patent applications, and/or launch start-up companies

A 1905 map of MIT's Boston campus
Plaque in Building 6 honoring George Eastman, founder of Eastman Kodak, who was revealed as the anonymous "Mr. Smith" who helped maintain MIT's independence
The MIT Media Lab houses researchers developing novel uses of computer technology and shown here is the 1982 building, designed by I.M. Pei, with an extension (right of photo) designed by Fumihiko Maki opened in March 2010
The central and eastern sections of MIT's campus as seen from above Massachusetts Avenue and the Charles River. Left of center is the Great Dome overlooking Killian Court, with Kendall Square to the upper right.
MIT's Building 10 and Great Dome overlooking Killian Court
Lobby 7 (at 77 Massachusetts Avenue) is regarded as the main entrance to campus

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