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The mitochondrial genome of Paragyrodactylus variegatus (Platyhelminthes: Monogenea): differences in major non-coding region and gene order compared to Gyrodactylus.

Ye F, King SD, Cone DK, You P - Parasit Vectors (2014)

Bottom Line: The gene order (tRNAGln, tRNAMet and NCR) differs in arrangement compared to the mitochondrial genomes reported from Gyrodactylus spp.Both morphological characters and characteristics of the mitochondrial genome support Paragyrodactylus as a distinct genus from Gyrodactylus.Considering their specific distribution and known hosts, we believe that Paragyrodactylus is a relict freshwater lineage of viviparous monogenean isolated in the high plateaus of central Asia on closely related river loaches.

View Article: PubMed Central - PubMed

Affiliation: Co-Innovation Center for Qinba regions' sustainable development, College of Life Science, Shaanxi Normal University, Xi'an 710062, China. youping@snnu.edu.cn.

ABSTRACT

Background: Paragyrodactylus Gvosdev and Martechov, 1953, a viviparous genus of ectoparasite within the Gyrodactylidae, contains three nominal species all of which infect Asian river loaches. The group is suspected to be a basal lineage within Gyrodactylus Nordmann, 1832 sensu lato although this remains unclear. Further molecular study, beyond characterization of the standard Internal Transcribed Spacer region, is needed to clarify the evolutionary relationships within the family and the placement of this genus.

Methods: The mitochondrial genome of Paragyrodactylus variegatus You, King, Ye and Cone, 2014 was amplified in six parts from a single worm, sequenced using primer walking, annotated and analyzed using bioinformatic tools.

Results: The mitochondrial genome of P. variegatus is 14,517 bp, containing 12 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and a major non-coding region (NCR). The overall A + T content of the mitochondrial genome is 76.3%, which is higher than all reported mitochondrial genomes of monogeneans. All of the 22 tRNAs have the typical cloverleaf secondary structure, except tRNACys, tRNASer1 and tRNASer2 that lack the dihydrouridine (DHU) arm. There are six domains (domain III is absent) and three domains in the inferred secondary structures of the large ribosomal subunit (rrnL) and small ribosomal subunit (rrnS), respectively. The NCR includes six 40 bp tandem repeat units and has the double identical poly-T stretches, stem-loop structure and some surrounding structure elements. The gene order (tRNAGln, tRNAMet and NCR) differs in arrangement compared to the mitochondrial genomes reported from Gyrodactylus spp.

Conclusion: The Duplication and Random Loss Model and Recombination Model together are the most plausible explanations for the variation in gene order. Both morphological characters and characteristics of the mitochondrial genome support Paragyrodactylus as a distinct genus from Gyrodactylus. Considering their specific distribution and known hosts, we believe that Paragyrodactylus is a relict freshwater lineage of viviparous monogenean isolated in the high plateaus of central Asia on closely related river loaches.

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The genetic distance of protein and rRNA genes ofParagyrodactylus variegatusandGyrodactylusspp.
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Fig4: The genetic distance of protein and rRNA genes ofParagyrodactylus variegatusandGyrodactylusspp.

Mentions: The Ka/Ks values for all 12 PCGs of P. variegatus versus Gyrodactylus spp. are presented, which all are less than 0.3. The highest average Ka/Ks value is ND2 (0.29), while the Ka/Ks ratios of half the PCGs are low (Ka/Ks < 0.1). The genetic distance between P. variegatus and the three reported species of Gyrodactylus (G. thymalli, G. salaris and G. derjavinoides) are much greater than among the three species of Gyrodactylus (Figure 4). The maximum divergence occurs in ND5 gene (48.9%) between P. variegatus and G. salaris. In addition, the genetic distances of rRNA genes are lower than protein genes (Figure 4).Figure 4


The mitochondrial genome of Paragyrodactylus variegatus (Platyhelminthes: Monogenea): differences in major non-coding region and gene order compared to Gyrodactylus.

Ye F, King SD, Cone DK, You P - Parasit Vectors (2014)

The genetic distance of protein and rRNA genes ofParagyrodactylus variegatusandGyrodactylusspp.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150975&req=5

Fig4: The genetic distance of protein and rRNA genes ofParagyrodactylus variegatusandGyrodactylusspp.
Mentions: The Ka/Ks values for all 12 PCGs of P. variegatus versus Gyrodactylus spp. are presented, which all are less than 0.3. The highest average Ka/Ks value is ND2 (0.29), while the Ka/Ks ratios of half the PCGs are low (Ka/Ks < 0.1). The genetic distance between P. variegatus and the three reported species of Gyrodactylus (G. thymalli, G. salaris and G. derjavinoides) are much greater than among the three species of Gyrodactylus (Figure 4). The maximum divergence occurs in ND5 gene (48.9%) between P. variegatus and G. salaris. In addition, the genetic distances of rRNA genes are lower than protein genes (Figure 4).Figure 4

Bottom Line: The gene order (tRNAGln, tRNAMet and NCR) differs in arrangement compared to the mitochondrial genomes reported from Gyrodactylus spp.Both morphological characters and characteristics of the mitochondrial genome support Paragyrodactylus as a distinct genus from Gyrodactylus.Considering their specific distribution and known hosts, we believe that Paragyrodactylus is a relict freshwater lineage of viviparous monogenean isolated in the high plateaus of central Asia on closely related river loaches.

View Article: PubMed Central - PubMed

Affiliation: Co-Innovation Center for Qinba regions' sustainable development, College of Life Science, Shaanxi Normal University, Xi'an 710062, China. youping@snnu.edu.cn.

ABSTRACT

Background: Paragyrodactylus Gvosdev and Martechov, 1953, a viviparous genus of ectoparasite within the Gyrodactylidae, contains three nominal species all of which infect Asian river loaches. The group is suspected to be a basal lineage within Gyrodactylus Nordmann, 1832 sensu lato although this remains unclear. Further molecular study, beyond characterization of the standard Internal Transcribed Spacer region, is needed to clarify the evolutionary relationships within the family and the placement of this genus.

Methods: The mitochondrial genome of Paragyrodactylus variegatus You, King, Ye and Cone, 2014 was amplified in six parts from a single worm, sequenced using primer walking, annotated and analyzed using bioinformatic tools.

Results: The mitochondrial genome of P. variegatus is 14,517 bp, containing 12 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and a major non-coding region (NCR). The overall A + T content of the mitochondrial genome is 76.3%, which is higher than all reported mitochondrial genomes of monogeneans. All of the 22 tRNAs have the typical cloverleaf secondary structure, except tRNACys, tRNASer1 and tRNASer2 that lack the dihydrouridine (DHU) arm. There are six domains (domain III is absent) and three domains in the inferred secondary structures of the large ribosomal subunit (rrnL) and small ribosomal subunit (rrnS), respectively. The NCR includes six 40 bp tandem repeat units and has the double identical poly-T stretches, stem-loop structure and some surrounding structure elements. The gene order (tRNAGln, tRNAMet and NCR) differs in arrangement compared to the mitochondrial genomes reported from Gyrodactylus spp.

Conclusion: The Duplication and Random Loss Model and Recombination Model together are the most plausible explanations for the variation in gene order. Both morphological characters and characteristics of the mitochondrial genome support Paragyrodactylus as a distinct genus from Gyrodactylus. Considering their specific distribution and known hosts, we believe that Paragyrodactylus is a relict freshwater lineage of viviparous monogenean isolated in the high plateaus of central Asia on closely related river loaches.

Show MeSH
Related in: MedlinePlus