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Fragmented mitochondrial genomes in two suborders of parasitic lice of eutherian mammals (Anoplura and Rhynchophthirina, Insecta).

Shao R, Barker SC, Li H, Song S, Poudel S, Su Y - Sci Rep (2015)

Bottom Line: The typical animal mitochondrial (mt) genome organization, which consists of a single chromosome with 37 genes, was found in chewing lice in the suborders Amblycera and Ischnocera.Each minichromosome is 3.5-4.2 kb in size and has 2-6 genes.Our results indicate that mt genome fragmentation is shared by the suborders Anoplura and Rhynchophthirina.

View Article: PubMed Central - PubMed

Affiliation: GeneCology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland 4556, Australia.

ABSTRACT
Parasitic lice (order Phthiraptera) infest birds and mammals. The typical animal mitochondrial (mt) genome organization, which consists of a single chromosome with 37 genes, was found in chewing lice in the suborders Amblycera and Ischnocera. The sucking lice (suborder Anoplura) known, however, have fragmented mt genomes with 9-20 minichromosomes. We sequenced the mt genome of the elephant louse, Haematomyzus elephantis - the first species of chewing lice investigated from the suborder Rhynchophthirina. We identified 33 mt genes in the elephant louse, which were on 10 minichromosomes. Each minichromosome is 3.5-4.2 kb in size and has 2-6 genes. Phylogenetic analyses of mt genome sequences confirm that the elephant louse is more closely related to sucking lice than to the chewing lice in the Amblycera and Ischnocera. Our results indicate that mt genome fragmentation is shared by the suborders Anoplura and Rhynchophthirina. Nine of the 10 mt minichromosomes of the elephant louse differ from those of the sucking lice (Anoplura) known in gene content and gene arrangement, indicating that distinct mt karyotypes have evolved in Anoplura and Rhynchophthirina since they diverged ~92 million years ago.

No MeSH data available.


Related in: MedlinePlus

Schematic illustration of the non-coding regions of the mitochondrial minichromosomes of the elephant louse, Haematomyzus elephantis.USFB1567 and ELR are the primers used to amplify the coding regions of all mitochondrial minichromosomes. A 346-bp unit (in green) repeated twice and a 225-bp unit (in yellow) repeated 4 times; the sequence similarity between/among the repeat copies of each unit is ~85%. A 99-bp sequence (in red) is present only in T-nad1-Q minichromosome.
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f2: Schematic illustration of the non-coding regions of the mitochondrial minichromosomes of the elephant louse, Haematomyzus elephantis.USFB1567 and ELR are the primers used to amplify the coding regions of all mitochondrial minichromosomes. A 346-bp unit (in green) repeated twice and a 225-bp unit (in yellow) repeated 4 times; the sequence similarity between/among the repeat copies of each unit is ~85%. A 99-bp sequence (in red) is present only in T-nad1-Q minichromosome.

Mentions: We sequenced the NCRs of four mt minichromosomes of the elephant louse in full length. The NCRs are 2,324, 2,457, 2,348 and 2,359 bp respectively for trnI-cox1-trnE, trnT-nad1-trnQ, trnK-nad4-trnC and trnH-nad5 minichromosomes, and account for 58%, 68%, 61% and 57% of the total size of each minichromosome (Fig. S1; Alignment S1). The NCR of T-nad1-Q minichromosome has a 99-bp sequence at the 3′ end, which is not seen in the NCRs of other minichromosomes. Otherwise, the NCRs of the four minichromosomes have high sequence similarity (>97%) to each other. Contrary to those of most animals, the NCRs of the elephant louse have higher GC content (thus lower AT content) than the coding regions: 40% vs 38% for trnI-cox1-trnE minichromosome, 39% vs 34% for trnT-nad1-trnQ minichromosome, 40% vs 34% for trnK-nad4-trnC minichromosome, and 41% vs 35% for trnH-nad5 minichromosome. Whether or not the high GC content in the NCRs has any functional significance to the fragmented mt genome of the elephant louse remains to be investigated. There are tandem-repeat units in the NCRs of the elephant louse, 225 and 346 bp in length, respectively. The 225-bp unit repeated four times whereas the 346-bp unit repeated twice; the different copies of each unit have ~85% identity to each other (Fig. 2). We also sequenced the NCRs of the other six minichromosomes of the elephant louse except for the GC-rich parts and the tandem-repeat parts using a Sanger sequencing platform (Fig. S2; Alignment S2). The exact length of the NCRs of these six minichromosomes was unknown. The full-length NCR sequences shown in Fig. S1 were the consensus sequences obtained from the assembly of the Illumina sequence-reads. The high coverage of the Illumina sequence-reads also revealed numerous heteroplasmic sites in these NCRs of the elephant louse (Table S2–S5), which is consistent with that observed in human lice and pig lice891122.


Fragmented mitochondrial genomes in two suborders of parasitic lice of eutherian mammals (Anoplura and Rhynchophthirina, Insecta).

Shao R, Barker SC, Li H, Song S, Poudel S, Su Y - Sci Rep (2015)

Schematic illustration of the non-coding regions of the mitochondrial minichromosomes of the elephant louse, Haematomyzus elephantis.USFB1567 and ELR are the primers used to amplify the coding regions of all mitochondrial minichromosomes. A 346-bp unit (in green) repeated twice and a 225-bp unit (in yellow) repeated 4 times; the sequence similarity between/among the repeat copies of each unit is ~85%. A 99-bp sequence (in red) is present only in T-nad1-Q minichromosome.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663631&req=5

f2: Schematic illustration of the non-coding regions of the mitochondrial minichromosomes of the elephant louse, Haematomyzus elephantis.USFB1567 and ELR are the primers used to amplify the coding regions of all mitochondrial minichromosomes. A 346-bp unit (in green) repeated twice and a 225-bp unit (in yellow) repeated 4 times; the sequence similarity between/among the repeat copies of each unit is ~85%. A 99-bp sequence (in red) is present only in T-nad1-Q minichromosome.
Mentions: We sequenced the NCRs of four mt minichromosomes of the elephant louse in full length. The NCRs are 2,324, 2,457, 2,348 and 2,359 bp respectively for trnI-cox1-trnE, trnT-nad1-trnQ, trnK-nad4-trnC and trnH-nad5 minichromosomes, and account for 58%, 68%, 61% and 57% of the total size of each minichromosome (Fig. S1; Alignment S1). The NCR of T-nad1-Q minichromosome has a 99-bp sequence at the 3′ end, which is not seen in the NCRs of other minichromosomes. Otherwise, the NCRs of the four minichromosomes have high sequence similarity (>97%) to each other. Contrary to those of most animals, the NCRs of the elephant louse have higher GC content (thus lower AT content) than the coding regions: 40% vs 38% for trnI-cox1-trnE minichromosome, 39% vs 34% for trnT-nad1-trnQ minichromosome, 40% vs 34% for trnK-nad4-trnC minichromosome, and 41% vs 35% for trnH-nad5 minichromosome. Whether or not the high GC content in the NCRs has any functional significance to the fragmented mt genome of the elephant louse remains to be investigated. There are tandem-repeat units in the NCRs of the elephant louse, 225 and 346 bp in length, respectively. The 225-bp unit repeated four times whereas the 346-bp unit repeated twice; the different copies of each unit have ~85% identity to each other (Fig. 2). We also sequenced the NCRs of the other six minichromosomes of the elephant louse except for the GC-rich parts and the tandem-repeat parts using a Sanger sequencing platform (Fig. S2; Alignment S2). The exact length of the NCRs of these six minichromosomes was unknown. The full-length NCR sequences shown in Fig. S1 were the consensus sequences obtained from the assembly of the Illumina sequence-reads. The high coverage of the Illumina sequence-reads also revealed numerous heteroplasmic sites in these NCRs of the elephant louse (Table S2–S5), which is consistent with that observed in human lice and pig lice891122.

Bottom Line: The typical animal mitochondrial (mt) genome organization, which consists of a single chromosome with 37 genes, was found in chewing lice in the suborders Amblycera and Ischnocera.Each minichromosome is 3.5-4.2 kb in size and has 2-6 genes.Our results indicate that mt genome fragmentation is shared by the suborders Anoplura and Rhynchophthirina.

View Article: PubMed Central - PubMed

Affiliation: GeneCology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland 4556, Australia.

ABSTRACT
Parasitic lice (order Phthiraptera) infest birds and mammals. The typical animal mitochondrial (mt) genome organization, which consists of a single chromosome with 37 genes, was found in chewing lice in the suborders Amblycera and Ischnocera. The sucking lice (suborder Anoplura) known, however, have fragmented mt genomes with 9-20 minichromosomes. We sequenced the mt genome of the elephant louse, Haematomyzus elephantis - the first species of chewing lice investigated from the suborder Rhynchophthirina. We identified 33 mt genes in the elephant louse, which were on 10 minichromosomes. Each minichromosome is 3.5-4.2 kb in size and has 2-6 genes. Phylogenetic analyses of mt genome sequences confirm that the elephant louse is more closely related to sucking lice than to the chewing lice in the Amblycera and Ischnocera. Our results indicate that mt genome fragmentation is shared by the suborders Anoplura and Rhynchophthirina. Nine of the 10 mt minichromosomes of the elephant louse differ from those of the sucking lice (Anoplura) known in gene content and gene arrangement, indicating that distinct mt karyotypes have evolved in Anoplura and Rhynchophthirina since they diverged ~92 million years ago.

No MeSH data available.


Related in: MedlinePlus