A novel fragmented mitochondrial genome in the protist pathogen Toxoplasma gondii and related tissue coccidia
Sivaranjani NamasivayamRodrigo P. BaptistaWenyuan XiaoErica M. HallJ. Stone DoggettKarin TroellJessica C. Kissinger
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Abstract:
Mitochondrial genome content and structure vary widely across the eukaryotic tree of life, with protists displaying extreme examples. Apicomplexan and dinoflagellate protists have evolved highly reduced mitochondrial genome sequences, mtDNA, consisting of only three cytochrome genes and fragmented rRNA genes. Here, we report the independent evolution of fragmented cytochrome genes in Toxoplasma and related tissue coccidia and evolution of a novel genome architecture consisting minimally of 21 sequence blocks (SBs) totaling 5.9 kb that exist as nonrandom concatemers. Single-molecule Nanopore reads consisting entirely of SBs ranging from 0.1 to 23.6 kb reveal both whole and fragmented cytochrome genes. Full-length cytochrome transcripts including a divergent coxIII are detected. The topology of the mitochondrial genome remains an enigma. Analysis of a cob point mutation reveals that homoplasmy of SBs is maintained. Tissue coccidia are important pathogens of man and animals, and the mitochondrion represents an important therapeutic target. The mtDNA sequence has been elucidated, but a definitive genome architecture remains elusive.Keywords:
Coccidia
Eukaryote
34 faecal specimens of captive adult cranes representing 5 species,collected in Zhengzhou Zoo,were examined to determine the prevalence and species of coccidian oocysts.The results showed that,the infection ratio of Coccidia was 35.29%,the average infection intensity(OPG) was 2.08×104.Three Coccidia spp.in cranes were discovered,namely,Eimeria gruis,Eimeria reichenowi and Isospora lacazei.
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Eukaryote genomes contain many noncoding regions, and they are quite complex. To understand these complexities, we constructed a database, Genome Composition Database, for the whole genome composition statistics for 101 eukaryote genome data, as well as more than 1,000 prokaryote genomes. Frequencies of all possible one to ten oligonucleotides were counted for each genome, and these observed values were compared with expected values computed under observed oligonucleotide frequencies of length 1–4. Deviations from expected values were much larger for eukaryotes than prokaryotes, except for fungal genomes. Mammalian genomes showed the largest deviation among animals. The results of comparison are available online at http://esper.lab.nig.ac.jp/genome-composition-database/.
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THE ease with which shells of eggs may become contaminated with the oocysts of coccidia has led many poultrymen to believe that chickens become infected with coccidia while in the incubator. Morse (1911) advocated that eggs that were to be incubated be washed with alcohol to free them from the oocysts of coccidia. Since oocysts of coccidia have been found to be very resistant to chemicals and very susceptible to drying when free from organic material (Fish 1931), hatcherymen generally have depended upon cleanliness and the natural drying of the eggs to free them from coccidia. Tyzzer (1932) and others have found that when they placed oocysts of coccidia upon the shells of incubating eggs, the oocysts did not survive the incubation period of the eggs. The incubator used by Tyzzer was not equipped with a humidifying device and the relative humidity of the incubator may have been lower than . . .
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Abstract Background Numerous cases of horizontal transfers (HTs) have been described for eukaryote genomes, but in contrast to prokaryote genomes, no whole genome evaluation of HTs has been carried out. This is mainly due to a lack of parametric methods specially designed to take the intrinsic heterogeneity of eukaryote genomes into account. We applied a simple and tested method based on local variations of genomic signatures to analyze the genome of the pathogenic fungus Aspergillus fumigatus . Results We detected 189 atypical regions containing 214 genes, accounting for about 1 Mb of DNA sequences. However, the fraction of atypical DNA detected was smaller than the average amount detected in the same conditions in prokaryote genomes (3.1% vs 5.6%). It appeared that about one third of these regions contained no annotated genes, a proportion far greater than in prokaryote genomes. When analyzing the origin of these HTs by comparing their signatures to a home made database of species signatures, 3 groups of donor species emerged: bacteria (40%), fungi (25%), and viruses (22%). It is to be noticed that though inter-domain exchanges are confirmed, we only put in evidence very few exchanges between eukaryotic kingdoms. Conclusions In conclusion, we demonstrated that HTs are not negligible in eukaryote genomes, bearing in mind that in our stringent conditions this amount is a floor value, though of a lesser extent than in prokaryote genomes. The biological mechanisms underlying those transfers remain to be elucidated as well as the biological functions of the transferred genes.
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Attempted infection of 2 young lambs with oocysts of Eimeria christenseni from a goat was unsuccessful. Negative results were obtained also when young kids were fed oocysts of Eimeria ninakohlyakimovae from sheep. There was no difficulty in infecting lambs with the sheep coccidium resembling E. ninakohlyakimovae nor goats with the goat coccidium E. christenseni. Oocysts from the goat measured 38.4 X 26.7 microns, but were easily distinguished from Eimeria ahsata from the sheep by sporocyst size and shape, and from Eimeria ovina by oocyst size. Eimeria ninakohlyakimovae-like oocysts from sheep averaged 23.0 X 18.2 microns and were morphologically indistinguishable from previously reported goat coccidia. Since no cross infections of sheep and goats could be accomplished with oocysts of Eimeria sp. characteristic of one or the other host, I concluded that sheep coccidia previously known as E. ninakohlykimovae are distinct from morphologically similar goat coccidia and therefore constitute a separate species. Since the name E. ninakohlyakimovae was first used for coccidia from the goat, the sheep coccidium is renamed Eimeria ovinoidalis with oocyst structure and endogenous stages similar to those previously described from the sheep.
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[Objective] To investigate the sensitivity of Eimeria coccidia strains isolated from two chicken farms in Anhui Province to different anti-coccidial drugs and provide a theoretical basis for coccidiosis treatment.[Method] The fresh feces were collected from two chicken farms,and Eimeria coccidia strains were isolated and propagated in laboratory.A total of eight anticoccidial drugs including diclazuril,robenidine,dinitolmide,decoquinate,nicarbazine,maduramicin,salinomycin and lasalocid were selected for sensitivity test.[Results] In Farm I,Eimeria coccidia strains were sensitive to decoquinate,partially resistant to nicarbazine and completely resistant to other six drugs.In Farm II,Eimeria coccidia strains were sensitive to decoquinate and nicarbazine,partially resistant to robenidine and completely resistant to other five drugs.[Conclusion] Drug resistance of Eimeria coccidia to many anticoccidial drugs had been highly developed in these two farms.
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1. Chickens were infected with Coccidia, considered to be Eimeria meleagridis , from turkeys. 2. Turkeys were subsequently infected with oocysts obtained from the chickens. 3. Slight variation from normal measurements of the coccidia in chickens is attributed to development in an abnormal host. 4. E. acervulina from chickens was not infective to a coccidia-free turkey chick.
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