@article {94795, title = {Fragmented mitochondrial genomes of the rat lice, Polyplax asiatica and Polyplax spinulosa: intra-genus variation in fragmentation pattern and a possible link between the extent of fragmentation and the length of life cycle}, journal = {BMC Genomics}, volume = {15}, year = {2014}, month = {01-2014}, pages = {44}, abstract = {

Background: Blood-sucking lice (suborder Anoplura) parasitize eutherian mammals with 67\% of the 540 described species found on rodents. The five species of blood-sucking lice that infest humans and pigs have fragmented mitochondrial genomes and differ substantially in the extent of fragmentation. To understand whether, or not,
any life-history factors are linked to such variation, we sequenced the mt genomes of Polyplax asiatica and Polyplax spinulosa, collected from the greater bandicoot rat, Bandicota indica, and the Asian house rat, Rattus tanezumi, respectively.
Results: We identified all of the 37 mitochondrial genes common to animals in Polyplax asiatica and Polyplax spinulosa. The mitochondrial genes of these two rat lice are on 11 circular minichromosomes; each minichromosome is 2\–4 kb long and has 2\–7 genes. The two rat lice share the same pattern for the distribution of the protein-coding genes and ribosomal RNA genes over the minichromosomes, but differ in the pattern for the distribution of 8 of the 22 transfer RNA genes. The mitochondrial genomes of the Polyplax rat lice have 3.4 genes, on average, on each minichromosome and, thus, are less fragmented than those of the human lice (2.1 and 2.4 genes per minichromosome), but are more fragmented than those of the pig lice (4.1 genes per minichromosome).
Conclusions: Our results revealed distinct patterns of mitochondrial genome fragmentation within the genus Polyplax and, furthermore, indicated a possible inverse link between the extent of mitochondrial genome fragmentation and the length of life cycle of the blood-sucking lice.

}, keywords = {Chromosome evolution, genome fragmentation, minichromosome, Mitochondrial genome, sucking lice}, issn = {1471-2164}, doi = {10.1186/1471-2164-15-44}, url = {http://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-15-44}, author = {Dong,Wen-ge and Simon Song and Dao-chao Jin and Guo,Xian-guo and Renfu Shao} } @article {94794, title = {Fragmented mitochondrial genomes are present in both major clades of the blood-sucking lice (suborder Anoplura): evidence from two Hoplopleura rodent lice (family Hoplopleuridae)}, journal = {BMC Genomics}, volume = {15}, year = {2014}, month = {Sept-2014}, pages = {13 pp}, abstract = {

Background: The suborder Anoplura contains 540 species of blood-sucking lice that parasitize over 840 species of eutherian mammals. Fragmented mitochondrial (mt) genomes have been found in the lice of humans, pigs, horses and rats from four families: Pediculidae, Pthiridae, Haematopinidae and Polyplacidae. These lice, eight species in total, are from the same major clade of the Anoplura. The mt genomes of these lice consist of 9\–20 minichromosomes; each minichromosome is 1.5\–4 kb in size and has 1\–8 genes. To understand mt genome fragmentation in the other major clade of the Anoplura, we sequenced the mt genomes of two species of rodent lice in the genus Hoplopleura (family Hoplopleuridae).
Results: We identified 28 mt genes on 10 minichromosomes in the mouse louse, Ho. akanezumi; each minichromosome is 1.7\–2.7 kb long and has 1\–6 genes. We identified 34 mt genes on 11 minichromosomes in the rat louse, Ho. kitti; each minichromosome is 1.8\–2.8 kb long and has 1\–5 genes. Ho. akanezumi also has a chimeric minichromosome with parts of two rRNA genes and a full-length tRNA gene for tyrosine. These two rodent lice share the same pattern for the distribution of all of the protein-coding and rRNA genes but differ in tRNA gene content and gene arrangement in four minichromosomes. Like the four genera of blood-sucking lice that have been investigated in previous studies, the Hoplopleura species have four minichromosomes that are only found in this genus.
Conclusions: Our results indicate that fragmented mt genomes were present in the most recent common ancestor of the two major clades of the blood-sucking lice, which lived ~75 million years ago. Intra-genus variation in the pattern of mt genome fragmentation is common in the blood-sucking lice (suborder Anoplura) and genus- specific minichromosomes are potential synapomorphies. Future studies should expand into more species, genera and families of blood-sucking lice to explore further the phylogenetic utility of the novel features associated with fragmented mt genomes.

}, keywords = {Chromosome evolution, genome fragmentation, minichromosome, Mitochondrial genome, sucking lice}, issn = {1471-2164}, doi = {10.1186/1471-2164-15-751}, url = {http://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-15-751}, author = {Dong,Wen-ge and Simon Song and Guo,Xian-guo and Dao-chao Jin and Qianqian Yang and Stephen C. Barker and Renfu Shao} } @article {94793, title = {Understanding mitochondrial genome fragmentation in parasitic lice (Insecta: Phthiraptera)}, journal = {Hereditas (Beijing)}, volume = {35}, year = {2013}, pages = {847 - 855}, abstract = {

Paper written in Chinese, Title:\ 虱 目裂 化 线 粒 体 基 因组 研 究 进 展

Abstract: Lice are obligateectoparasites of mammals and birds. Extensiver fagmentation of mitochondrial genomes has been found in some louse \ species in the families Pediculidae,Pthiridae,Philopteridae and Trichodectidae. For example, the\ mt genomes of human body louse ( Pediculus humanus), head louse (Pediculus humanus capitis), and pubic louse (Pthirus pubis) have 20, 20 and 14 mini-chromosomes,respectively.These mini-chromosomes might be the results of deletion and\ recombination of mt genes .The factors and mechanism s of mitochondrial genome fragmentation are currently unknown. The fragmentation might be the results of evolutionary selection or random genetic drift or it is probably related to the lack of mtSSB (mitochondrial single-strand DNA binding protein).Understanding the fragmentation of mitochondrial genomes is \ of significance for understanding the origin and evolution of mitochondria. This paper reviews the recent advances in the studies of mitochondrial genome fragmentation in lice, including the phenomena of mitochrondrial genome fragmentation, characteristics of fragmentated mitochondrial genomes, and some factors and mechanism possibly leading to the mitochondrial genome fragmentation of lice.Perspectives for future studies on fragmented mt genomes arealso discussed.

}, keywords = {Chromosome evolution, genome fragmentation, Mitochondrial genome}, issn = {0253-9772}, doi = {10.3724/SP.J.1005.2013.00847}, url = {https://www.researchgate.net/publication/249321853_Understanding_mitochondrial_genome_fragmentation_in_parasitic_lice_Insecta_Phthiraptera}, author = {Dong,Wen-ge and Guo,Xian-guo and Dao-chao Jin and Shi-peng Xue and Simon Song and Stephen C. Barker and Renfu Shao} } @article {94401, title = {The Mitochondrial Genome of the Guanaco Louse, Microthoracius praelongiceps: Insights into the Ancestral Mitochondrial Karyotype of Sucking Lice (Anoplura, Insecta)}, journal = {Genome Biology and Evolution}, volume = {9}, year = {2017}, month = {Mar-23-2017}, pages = {431 - 445}, abstract = {

Fragmented mitochondrial (mt) genomes have been reported in 11 species of sucking lice (suborder Anoplura) that infest humans, chimpanzees, pigs, horses, and rodents. There is substantial variation among these lice in mt karyotype: the number of minichromosomes of a species ranges from 9 to 20; the number of genes in a minichromosome ranges from 1 to 8; gene arrangement in a minichromosome differs between species, even in the same genus. We sequenced the mt genome of the guanaco louse, Microthoracius praelongiceps, to help establish the ancestral mt karyotype for sucking lice and understand how fragmented mt genomes evolved. The guanaco louse has 12 mt minichromosomes; each minichromosome has 2\–5 genes and a non-coding region. The guanaco louse shares many features with rodent lice in mt karyotype, more than with other sucking lice. The guanaco louse, however, is more closely related phylogenetically to human lice, chimpanzee lice, pig lice, and horse lice than to rodent lice. By parsimony analysis of shared features in mt karyotype, we infer that the most recent common ancestor of sucking lice, which lived ~75 Ma, had 11 minichromosomes; each minichromosome had 1\–6 genes and a non-coding region. As sucking lice diverged, split of mt minichromosomes occurred many times in the lineages leading to the lice of humans, chimpanzees, and rodents whereas merger of minichromosomes occurred in the lineage leading to the lice of pigs and horses. Together, splits and mergers of minichromosomes created a very complex and dynamic mt genome organization in the sucking lice.

}, keywords = {genome fragmentation, guanaco, minichromosome, Mitochondrial genome, sucking lice.}, doi = {10.1093/gbe/evx007}, url = {https://academic.oup.com/gbe/article-lookup/doi/10.1093/gbe/evx007}, author = {Renfu Shao and Hu Li and Stephen C. Barker and Simon Song} } @article {94284, title = {Fragmented mitochondrial genomes in two suborders of parasitic lice of eutherian mammals (Anoplura and Rhynchophthirina, Insecta)}, journal = {Scientific Reports}, volume = {5}, year = {2015}, month = {Jun-15-2015}, pages = {11pp}, 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.

}, doi = {10.1038/srep17389}, url = {http://www.nature.com/articles/srep17389}, author = {Renfu Shao and Stephen C. Barker and Hu Li and Simon Song and Shree Kanta S. Poudel and Yuan Su} }