Molecular genetic diversity and characterization of conjugation genes in the fish parasite Ichthyophthirius multifiliis

MacColl, Elisabeth; Therkelsen, Matthew D.; Lama-Sherpa, Tshering; Ellerbrock, Hannah; Johnston, Lily A.; Jariwala, Ravi; Chang, Wei‐Jen; Gurtowski, James; Schatz, Michael C.; Hossain, M. Mozammal; Cassidy-Hanley, Donna; Clark, Theodore G.

doi:10.1016/j.ympev.2015.02.017

Cited by 17 publications

(33 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Indeed, it is highly questionable whether Ichthyophthirius has sexual reproduction since conjugation in Ichthyophthirius has not been studied in depth to date. Although in a very recent study, population genetics data showed that this organism also reproduces sexually, but that conjugation-related genes in this ciliate are poorly-conserved compared to Tetrahymena , suggesting that mechanical differences between Ichthyophthirius and other ciliates may exist (MacColl et al, 2015). Therefore, currently it is difficult to speculate about the role of ATG genes during PND in Ichthyophthirius .…”

Section: Discussionmentioning

confidence: 98%

A comparative in-silico analysis of autophagy proteins in ciliates

Aslan

Küçükoğlu

Arslanyolu

2017

PeerJ

View full text Add to dashboard Cite

Autophagy serves as a turnover mechanism for the recycling of redundant and/or damaged macromolecules present in eukaryotic cells to re-use them under starvation conditions via a double-membrane structure known as autophagosome. A set of eukaryotic genes called autophagy-related genes (ATGs) orchestrate this highly elaborative process. The existence of these genes and the role they play in different eukaryotes are well-characterized. However, little is known of their role in some eukaryotes such as ciliates. Here, we report the computational analyses of ATG genes in five ciliate genomes to understand their diversity. Our results show that Oxytricha trifallax is the sole ciliate which has a conserved Atg12 conjugation system (Atg5-Atg12-Atg16). Interestingly, Oxytricha Atg16 protein includes WD repeats in addition to its N-terminal Atg16 domain as is the case in multicellular organisms. Additionally, phylogenetic analyses revealed that E2-like conjugating protein Atg10 is only present in Tetrahymena thermophila. We fail to find critical autophagy components Atg5, Atg7 and Atg8 in the parasitic ciliate Ichthyophthirius multifiliis. Contrary to previous reports, we also find that ciliate genomes do not encode typical Atg1 since all the candidate sequences lack an Atg1-specific C-terminal domain which is essential for Atg1 complex formation. Consistent with the absence of Atg1, ciliates also lack other members of the Atg1 complex. However, the presence of Atg6 in all ciliates examined here may rise the possibility that autophagosome formation could be operated through Atg6 in ciliates, since Atg6 has been shown as an alternative autophagy inducer. In conclusion, our results highlight that Atg proteins are partially conserved in ciliates. This may provide a better understanding for the autophagic destruction of the parental macronucleus, a developmental process also known as programmed nuclear death in ciliates.

show abstract

Section: Discussionmentioning

confidence: 98%

A comparative in-silico analysis of autophagy proteins in ciliates

Aslan

Küçükoğlu

Arslanyolu

2017

PeerJ

View full text Add to dashboard Cite

show abstract

“…We also find two SSU rDNA haplotypes differing by three nucleotides in C. irritans. In I. multifiliis only one SSU rDNA haplotype was detected at this locus among 9 isolates (MacColl, et al, 2015). The two SSU rDNA haplotypes detected in C. irritans also distinguish Group I isolates from Group II.…”

Section: Discussionmentioning

confidence: 86%

“…Similar approaches have been applied to and yield successful outcomes in detecting both intra-and interspecies variation in Tetrahymena spp. (Chantangsi, et al, 2007;Chantangsi and Lynn, 2008), and intraspecies variations in another ciliate parasite, Ichthyophthirius multifiliis (MacColl, et al, 2015). Based on cox-1 sequences C. irritans can be divided into two distinct groups, I and II, with 9.29% sequence divergence between these two groups, which is far greater than some interspecies divergences in Tetrahymena spp.…”

Section: Discussionmentioning

confidence: 99%

“…Its DNA sequence is also longer (full length ~ 2,500 nt), and can potentially provide more evolutionary signals: both GenBank and the Consortium for the Barcode of Life use cox-1 sequences as their default DNA barcoding sequences. Recent successes in using cox-1 sequences to classify isolates of another ciliate parasite, Ichthyophthirius multifiliis, also suggest a similar approach may be applicable to help characterize isolates of C. irritans at the molecular level (MacColl, et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High genetic diversities between isolates of the fish parasite Cryptocaryon irritans (Ciliophora) suggest multiple cryptic species

Chi

Taik

Foley

et al. 2017

Molecular Phylogenetics and Evolution

Self Cite

View full text Add to dashboard Cite

The ciliate protozoan Cryptocaryon irritans parasitizes marine fish and causes lethal white spot disease. Sporadic infections as well as large-scale outbreaks have been reported globally and the parasite's broad host range poses particular threat to the aquaculture and ornamental fish markets. In order to better understand C. irritans' population structure, we sequenced and compared mitochondrial cox-1, SSU rRNA, and ITS-1 sequences from 8 new isolates of C. irritans collected in China, Japan, and Taiwan. We detected two SSU rRNA haplotypes, which differ at three positions, separating the isolates into two main groups (I and II). Cox-1 sequences also support the division into two groups, and the cox-1 divergence between these two groups is unexpectedly high (9.28% for 1582 nucleotide positions). The divergence is much greater than that detected in Ichthyophthirius multifiliis, the ciliate protozoan causing freshwater white spot disease in fish, where intraspecies divergence on cox-1 sequence is only 1.95%. ITS-1 sequences derived from these eight isolates and from all other C. irritans isolates (deposited in the GenBank) not only support the two groups, but further suggest the presence of a third group with even greater sequence divergence. Finally, a small Ka/Ks ratio estimated from cox-1 sequences suggests that this gene in C. irritans remains under strong purifying selection. Taken together, the C. irritans species may consists of many subspecies and/or syngens. Further work is needed to determine if there is reproductive isolation between the groups we have defined.

show abstract

“…Ichthyophthirius has sexual reproduction since conjugation in Ichthyophthirius has not been studied in depth to date. Although in a very recent study, population genetics data showed that this organism also reproduces sexually, but that conjugation-related genes in this ciliate are poorlyconserved compared to Tetrahymena, suggesting that mechanical differences between Ichthyophthirius and other ciliates may exist (MacColl et al, 2015). Therefore, currently it is difficult to speculate about the role of ATG genes during PND in Ichthyophthirius.…”

Section: Discussionmentioning

confidence: 91%

Peer Review #1 of "A comparative in-silico analysis of autophagy proteins in ciliates (v0.1)"

2017

View full text Add to dashboard Cite

Autophagy serves as a turnover mechanism for the recycling of redundant and/or damaged macromolecules present in eukaryotic cells to re-use them under starvation conditions via a double-membrane structure, autophagosome. A set of eukaryotic genes called autophagy-related genes (ATGs) orchestrate this highly elaborative process. The existence of these genes and the role they play in different eukaryotes are wellcharacterized. However, little is known of their role in some eukaryotes, like ciliates. Here, we report the computational analyses of ATG genes in five ciliate genomes to understand their diversity. Our results show that Oxytricha trifallax is the sole ciliate which has a conserved Atg12 conjugation system (Atg5-Atg12-Atg16). Interestingly, Oxytricha Atg16 protein includes WD repeats in addition to its N-terminal Atg16 domain as is the case in multicellular organisms. Additionally, phylogenetic analyses revealed that E2-like conjugating protein Atg10 is only present in Tetrahymena thermophila. We fail to find critical autophagy components Atg5, Atg7 and Atg8 in the parasitic ciliate Ichthyophthirius multifiliis. Contrary to previous reports, we also find that ciliate genomes do not encode typical Atg1 since all the candidate sequences lack an Atg1-specific C-terminal domain which is essential for Atg1 complex formation. Consistent with the absence of Atg1, ciliates also lack other members of the Atg1 complex. However presence of Atg6 in all ciliates examined here may rise the possibility that autophagosome formation could be operated through Atg6 in ciliates, since Atg6 has been shown as an alternative autophagy inducer. In conclusion, our results highlight that Atg proteins are partially conserved in ciliates. This may provide a better understanding for the autophagic destruction of the parental macronucleus, a developmental process also known as programmed nuclear death in ciliates.

show abstract

Molecular genetic diversity and characterization of conjugation genes in the fish parasite Ichthyophthirius multifiliis

Cited by 17 publications

References 48 publications

A comparative in-silico analysis of autophagy proteins in ciliates

A comparative in-silico analysis of autophagy proteins in ciliates

High genetic diversities between isolates of the fish parasite Cryptocaryon irritans (Ciliophora) suggest multiple cryptic species

Peer Review #1 of "A comparative in-silico analysis of autophagy proteins in ciliates (v0.1)"

Contact Info

Product

Resources

About