Divergent nuclear 18S rDNA paralogs in a turkey coccidium, Eimeria meleagrimitis, complicate molecular systematics and identification

El-Sherry, Shiem; Ogedengbe, Mosun E.; Hafeez, Mian Abdul; Barta, John R.

doi:10.1016/j.ijpara.2013.03.005

Cited by 61 publications

(40 citation statements)

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“…Line 5 was used for all experiments described herein. The sequence of the mitochondrial cytochrome c oxidase subunit I (mtCOI) and nuclear small subunit 18S rDNA (nu 18S) loci of this singleoocyst-derived line of E. adenoeides has been previously reported by El-Sherry et al (2013). Sporulation of the oocysts were conducted by suspending them in 2.5 % potassium dichromate and incubated at 26°C on a rotary shaker for a minimum of 72 h. Oocysts were then washed from the potassium dichromate by centrifugation (1,000×g for 10 min), resuspended in1× phosphate buffered saline (PBS), and stored at 4°C.…”

Section: Methodsmentioning

confidence: 86%

“…Oocyst morphometrics, endogenous and exogenous biological features of this strain, as well as oocyst shedding patterns and overall parasite fecundity are presented to complement previously reported molecular characterization of the E. adenoeides Guelph strain (El-Sherry et al 2013). The present study addresses the lack of stability of the species concept for E. adenoeides Moore and Brown 1951 by providing a formal taxonomic re-description for this important pathogen of turkeys, including designation and deposition of neotypes linked to multilocus genetic markers.…”

Section: Introductionmentioning

confidence: 84%

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Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria adenoeides Moore and Brown, 1951

et al. 2014

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The Guelph strain of Eimeria adenoeides was obtained from a commercial turkey flock in Ontario, Canada, in 1985. Single oocyst derived lines of E. adenoeides were propagated, and one of them used to re-describe biological and morphological features of E. adenoeides in the turkey. Oocysts of this strain are within the lower size ranges in the original species description reported by Moore and Brown (1951); oocysts of the Guelph strain averaged 18.7 ± 1.4 μm (16.7-22.5) by 14.3 ± 0.9 μm (13-16.2, n = 30) with a shape index (SI) of 1.3 ± 0.1. It is possible that the original species description was based, at least in part, on a mixed culture of two or more Eimeria species. Immature first-generation meronts of E. adenoeides Guelph strain were observed histologically at 32 h post-infection in the ileum and cecal neck. Early studies reported only two asexual generations suggested that first asexual cycle observed at 32 h post-infection was overlooked. In the present study, three asexual generations were observed before the start of gametogony. The Guelph strain is also characterized by a prepatent period of 112 h. The Guelph strain of E. adenoeides is a highly pathogenic coccidium that forms classic cecal lesions, including prominent caseous cecal cores, during moderate to severe infections. The maximum output of oocysts (1.77 × 10(7) per bird) was obtained from birds inoculated with 1 × 10(3) oocysts; maximum fecundity (1.55 × 10(5) oocyst shed per oocyst inoculated) was obtained with an inoculation of 1 × 10(2) oocysts, but fecundity dropped dramatically as the inoculation dose increased. To promote stability of the E. adenoeides species concept, neotype specimens (a parahapantotype slides series and phototype) have been designated and deposited for future reference.

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Section: Methodsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 84%

Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria adenoeides Moore and Brown, 1951

et al. 2014

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“…The well-documented intraspecific heterogeneity in the 18S rRNA gene of several Sarcocystis spp. has not received as much attention as similar findings in other apicomplexan genera like Plasmodium, Cryptosporidium, Babesia, Theileria and Eimeria (see Bhoora et al 2009;Vrba et al 2011;El-Sherry et al 2013), possibly because this interesting feature has not been sufficiently emphasised in the associated papers. The intra-isolate variability in the 18S rRNA gene of Sarcocystis spp.…”

Section: Discussionmentioning

confidence: 99%

Molecular characterisation of three regions of the nuclear ribosomal DNA unit and the mitochondrial cox1 gene of Sarcocystis fusiformis from water buffaloes (Bubalus bubalis) in Egypt

2015

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A total of 33 macroscopically visible (3-11 × 1-5 mm) sarcocysts of Sarcocystis fusiformis were excised from the oesophagus of 12 freshly slaughtered water buffalos in Giza, Egypt. Genomic DNA was extracted from the sarcocysts, and all isolates were characterised at the mitochondrial cytochrome c oxidase subunit I (cox1) gene through PCR amplification and direct sequencing, whereas a few selected isolates were characterised at the 18S and 28S ribosomal (r) RNA genes and the internal transcribed spacer 1 (ITS1) region of the nuclear rDNA unit following cloning. Among the 33 cox1 sequences (1,038-bp long), there was a total of 13 haplotypes, differing from each other by one to seven substitutions and sharing an identity of 99.3-99.9 %. In comparison, the sequence identity was 98.8-99.0 % among eight complete 18S rRNA gene sequences (1,873-1,879-bp long), 98.1-100 % among 28 complete ITS1 sequences (853-864-bp long) and 97.4-99.6 % among five partial 28S rRNA gene sequences (1,607-1,622 bp). At the three nuclear loci, the intraspecific (and intra-isolate) sequence variation was due to both substitutions and indels, which necessitated cloning of the PCR products before sequencing. Some additional clones of the 18S and 28S rRNA genes were highly divergent from the more typical clones, but the true nature of these aberrant clones could not be determined. Sequence comparisons and phylogenetic analyses based on either 18S rRNA gene or cox1 nucleotide sequences, placed S. fusiformis closest to Sarcocystis cafferi from the African buffalo, but only the analyses based on cox1 data separated the two taxa clearly from each other and showed that they were separate species (monophyletic clusters and 93 % sequence identity at cox1 versus interleaved sequences and 98.7-99.1 % sequence identity at the 18S rRNA gene). Two cats experimentally infected with sarcocysts of S. fusiformis started shedding small numbers of sporocysts 8-10 days post-infection (dpi) and were euthanized 15 dpi. Sporocysts isolated from the intestinal mucosa of both cats were identified molecularly as belonging to S. fusiformis through PCR amplification and sequencing of the partial cox1. The two sporocyst-derived cox1 sequences were identical with the most common sarcocyst-derived cox1 haplotype.

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“…For example, Plasmodium, Eimeria, and Toxoplasma spp. (22)(23)(24) are known to contain dispersed and highly divergent 18S rDNAs in their genome. Diversity of sequence among the repeats of rDNA has been shown for flatworms that may have a few distinct rRNA types maintained within the genome (25).…”

Section: Discussionmentioning

confidence: 99%

Candida inconspicua and Candida norvegensis: New Insights into Identification in Relation to Sexual Reproduction and Genome Organization

et al. 2015

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Candida inconspicua and Candida (Pichia) norvegensis are two emerging pathogenic species that exhibit reduced susceptibility to azole derivatives. Conventional (biochemical) approaches do not readily differentiate between the two species. The first aim of this work was to analyze the performance of biochemical, proteomic (matrix-assisted laser desorption ionization-time of flight [MALDI-TOF]), and molecular approaches in the precise identification of these species. These results then led us to sequence 3 genomic loci, i.e., the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA), the D1/D2 domain of the 28S rDNA, and the elongation factor 1␣ (EF-1␣) gene, either directly or following cloning, of 13 clinical isolates and 9 reference strains belonging to the 5 species included in the Pichia cactophila clade, namely, Pichia cactophila, Pichia insulana, C. inconspicua, C. norvegensis, and P. pseudocactophila. Finally, isolates of C. inconspicua were challenged for sexual reproduction on the appropriate medium. Our results show that EF-1␣ sequencing and proteic profiling by MALDI-TOF are the two most efficient approaches to distinguish between C. norvegensis and C. inconspicua. As a characteristic of the P. cactophila clade, we found multiple alleles of the rDNA regions in certain strains belonging to the tested species, making ITS or D1/D2 sequencing not appropriate for identification. Whatever the method of identification, including MALDI-TOF and EF-1␣ sequencing, none could differentiate C. inconspicua from P. cactophila. The results of phylogenetic analysis and the generation of asci from pure cultures of all C. inconspicua strains both support the identification of P. cactophila as the teleomorph of C. inconspicua. Candida spp. remain the predominant cause of invasive fungal infections (1). The incidence of candidemia, the main clinical form of invasive candidiasis, significantly increased in the 1980s (2). Concomitantly, non-C. albicans species have emerged among the causative agents of candidiasis (3). The reasons for this emergence remain unclear, but selective pressure due to a larger use of azole derivatives has been suggested (4). Indeed, in addition to C. glabrata and C. krusei, the two main fluconazole-resistant species isolated from patients with candidemia, a number of fluconazoleresistant species are now regularly isolated from deep-seated infections. Together, these "rare" species may account for as much as 10% of the etiologic agents in some medical centers (5).Candida inconspicua and Candida norvegensis (teleomorph [tel.]: Pichia norvegensis) are among those fluconazole-resistant emerging species that are more frequently isolated from invasive infections (6). In addition to this increasing concern, these two species are known to be difficult to differentiate from each other using routine techniques such as biochemical panels. Indeed, auxanograms such as ID32C differentiate the two species only according to the hydrolysis of esculin, a phenotypic trait whose variability is well know...

show abstract

Divergent nuclear 18S rDNA paralogs in a turkey coccidium, Eimeria meleagrimitis, complicate molecular systematics and identification

Cited by 61 publications

References 30 publications

Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria adenoeides Moore and Brown, 1951

Re-description of a genetically typed, single oocyst line of the turkey coccidium, Eimeria adenoeides Moore and Brown, 1951

Molecular characterisation of three regions of the nuclear ribosomal DNA unit and the mitochondrial cox1 gene of Sarcocystis fusiformis from water buffaloes (Bubalus bubalis) in Egypt

Candida inconspicua and Candida norvegensis: New Insights into Identification in Relation to Sexual Reproduction and Genome Organization

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