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Acknowledgments: This work was supported by grants from
the National Basic Research Program of China (2010CB912400
to P.Z., 2011CB966300 to G.L., and 2009CB825500 to
R.M.X. and P.Z.); the National Natural Science Foundation
of China (91219202 to G.L., 31230018 to P.Z., 91019007 to
G.L., 21261130090 to P.Z., and 31000566 to P.C.); Strategic
Priority Research Program (XDA01010304 to G.L. and
XDB08010100 to P.Z. and R.M.X.) and Key Research
Program (KJZD-EW-L05 to P.Z., G.L., and R.M.X.) from the
Chinese Academy of Sciences; and the Scientific Research
Foundation for the Returned Overseas Chinese Scholars,
State Education Ministry, to P.C. All EM data were collected
and processed at the Center for Bio-imaging, Institute of
Biophysics, Chinese Academy of Sciences. We thank G. Ji
and X. Huang for their technical help and support with
electron microscopy and L. Ling for technical help and
support with the data processing in the High Performance
Computing Service Station. We are also indebted to the
colleagues whose work could not be cited because of the
limitation of space. The cryo-EM maps for the 12 × 177 bp,
12 × 187 bp and 24 × 177 bp chromatin fibers were
deposited into the Electron Microscopy Data Bank with the
accession codes EMD-2600, EMD-2601 and EMD-2602,
respectively. The authors declare no conflicts of interest.
Materials and Methods
Figs. S1 to S8
Movies S1 to S3
28 January 2014; accepted 18 March 2014
Genome Sequence of the Tsetse
Fly (Glossina morsitans): Vector of
International Glossina Genome Initiative*†
Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa.
Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable
differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous
reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase
Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted
protein–encoding genes led to multiple discoveries, including chromosomal integrations of bacterial
(Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of
host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These
genome data provide a foundation for research into trypanosomiasis prevention and yield important
insights with broad implications for multiple aspects of tsetse biology.
African trypanosomiasis is transmitted by the tsetse fly to humans (sleeping sick- ness) and livestock (nagana) throughout
sub-Saharan Africa, with an estimated 70 million
people at risk of infection. Rearing livestock in
endemic areas is difficult to impossible and re-
sults in an economic loss in agricultural output of
several billion U.S. dollars per year. Human in-
fections are fatal if untreated, but tools for disease
control are limited because it has not been pos-
sible to develop vaccines and current trypanocidal
drug treatments result in undesirable side effects
with growing reports of drug resistance. The re-
duction or elimination of tsetse populations is an
effective method for disease control that could be
improved with greater knowledge of their biol-
ogy and genetics (1).
Tsetse flies are key representatives of the
dipteran clade Calyptratae, which represents 12%
of the known diversity within the dipteran order.
Many of the calyptrate species are blood feeders
of biomedical importance (2). In addition, mem-
bers of the calyptrate family of Glossinidae and
superfamily Hippoboscoidea, to which tsetse be-
long (fig. S1) (3), are defined by the ability to
nourish intrauterine offspring from glandular se-
cretions and give birth to fully developed larvae
(obligate adenotrophic viviparity). Tsetse flies live
considerably longer than other vector insects, which
somewhat compensates for their slow rate of repro-
duction. Trypanosome infections in tsetse are ac-
quired by blood feeding from an infected vertebrate
host, and trypanosomes have to overcome multiple
immune barriers to establish an infection within
the fly. As a result, trypanosome infection prev-
alence is low in field populations and in experi-
mentally infected tsetse (4). Tsetse have symbionts
that compensate for their nutritionally restricted
diet by the production of specific metabolites and
influence multiple other aspects of the fly’s im-
mune and reproductive physiology (5).
In 2004, the International Glossina Genome
Initiative (IGGI) was formed (6) to expand research capacity for Glossina, particularly in sub-Saharan Africa, through the generation and
distribution of molecular resources, including bioinformatics training. An outcome of the effort
undertaken by IGGI is the annotated Glossina
morsitans genome presented here and further
developed in satellite papers on genomic and
functional biology findings that reflect the unique
physiology of this disease vector (7–14).
Characteristics of the Glossina Genome
A combination of sequencing methods were used
to obtain the Glossina morsitans morsitans (Gmm)
genome, including Sanger sequencing of bacterial artificial chromosomes (BACs), small-insert
plasmid and large-insert fosmid libraries, and 454
and Illumina sequencing (tables S1 and S2). The
sequences were assembled into 13,807 scaffolds
of up to 25.4 Mb, with a mean size of 27 kb and
half the genome present in scaffolds of at least
120 kb. The 366-Mb genome is more than twice
the size of the Drosophila melanogaster genome
(fig. S2A and table S3). Clear conservation of
synteny was detected between Glossina and Drosophila, but with the blocks of synteny tending
to be twice as large in Glossina due to larger introns and an increase in the size of intergenic
sequences, possibly as a result of transposon
activity and/or repetitive sequence expansions.
Sequences from most of the major groups of
retrotransposons and DNA transposons are found
in the Glossina genome (table S4). These sequences comprise ~14% of the assembled genome, in contrast to 3.8% of the Drosophila
*Members of the International Glossina Genome Initiative,
affiliations, and individual contributions appear at the end of
†Corresponding author. E-mail: firstname.lastname@example.org
(Serap Aksoy); email@example.com (G.M.A.); mb4@