scholarly journals Functional conservation of mitochondrial RNA levels despite divergent mtDNA organization

2020 ◽  
Author(s):  
James P Held ◽  
Maulik R Patel

Abstract Objective: Mitochondria-encoded ribosomal RNA (rRNA) genes in humans are expressed at a higher rate than protein coding genes of the mitochondria. The organization of the human mitochondrial genome (mtDNA) is amenable to differential expression of rRNAs as the rRNA encoding genes lie in tandem immediately downstream of the promoter-containing region. However, mtDNA is not organized in the same way as humans in all metazoans. In the nematode, Caenorhabditis elegans, the rRNA genes are on opposite sides of the mtDNA molecule and there are no obvious promoter sequences specific to the rRNA genes. Thus, we asked whether rRNA levels are higher relative to mRNAs in mitochondria of C. elegans as they are in humans.Results: Using droplet digital PCR, we discovered that steady-state mitochondrial rRNA transcript levels are approximately 120 times higher than the levels of mitochondrial mRNAs. These data demonstrate that despite the lack of conservation in mitochondrial genome organization, a high mitochondrial rRNA-to-mRNA ratio is a conserved feature of metazoans.

2020 ◽  
Author(s):  
James P Held ◽  
Maulik R Patel

Abstract Objective: Mitochondria-encoded ribosomal RNA (rRNA) genes in humans are expressed at a higher rate than protein coding genes of the mitochondria. The organization of the human mitochondrial genome (mtDNA) is amenable to differential expression of rRNAs as it contains a promoter specific to the transcription of the two rRNAs. However, mtDNA is not organized in the same way as humans in all metazoans. In the nematode, Caenorhabditis elegans, the rRNA genes are on opposite sides of the mtDNA molecule and there are no obvious promoter sequences specific to the rRNA genes. Thus, we asked whether rRNA levels are higher relative to mRNAs in mitochondria of C. elegans as they are in humans.Results: Using droplet digital PCR, we discovered that steady-state mitochondrial rRNA transcript levels are approximately 120 times higher than the levels of mitochondrial mRNAs. These data demonstrate that despite the lack of conservation in mitochondrial genome organization, a high mitochondrial rRNA-to-mRNA ratio is a conserved feature of metazoans.


2018 ◽  
Vol 94 ◽  
Author(s):  
P. Zhang ◽  
R.K. Ran ◽  
A.Y. Abdullahi ◽  
X.L. Shi ◽  
Y. Huang ◽  
...  

AbstractDipetalonema gracile is a common parasite in squirrel monkeys (Saimiri sciureus), which can cause malnutrition and progressive wasting of the host, and lead to death in the case of massive infection. This study aimed to identify a suspected D. gracile worm from a dead squirrel monkey by means of molecular biology, and to amplify its complete mitochondrial genome by polymerase chain reaction (PCR) and sequence analysis. The results identified the worm as D. gracile, and the full length of its complete mitochondrial genome was 13,584 bp, which contained 22 tRNA genes, 12 protein-coding genes, two rRNA genes, one AT-rich region and one small non-coding region. The nucleotide composition included A (16.89%), G (20.19%), T (56.22%) and C (6.70%), among which A + T = 73.11%. The 12 protein-coding genes used TTG and ATT as start codons, and TAG and TAA as stop codons. Among the 22 tRNA genes, only trnS1AGN and trnS2UCN exhibited the TΨC-loop structure, while the other 20 tRNAs showed the TV-loop structure. The rrnL (986 bp) and rrnS (685 bp) genes were single-stranded and conserved in secondary structure. This study has enriched the mitochondrial gene database of Dipetalonema and laid a scientific basis for further study on classification, and genetic and evolutionary relationships of Dipetalonema nematodes.


PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242541
Author(s):  
Lvpei Du ◽  
Shanya Cai ◽  
Jun Liu ◽  
Ruoyu Liu ◽  
Haibin Zhang

Phymorhynchus is a genus of deep-sea snails that are most distributed in hydrothermal vent or cold seep environments. In this study, we presented the complete mitochondrial genome of P. buccinoides, a cold seep snail from the South China Sea. It is the first mitochondrial genome of a cold seep member of the superfamily Conoidea. The mitochondrial genome is 15,764 bp in length, and contains 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. These genes are encoded on the positive strand, except for 8 tRNA genes that are encoded on the negative strand. The start codon ATG and 3 types of stop codons, TAA, TAG and the truncated termination codon T, are used in the 13 PCGs. All 13 PCGs in the 26 species of Conoidea share the same gene order, while several tRNA genes have been translocated. Phylogenetic analysis revealed that P. buccinoides clustered with Typhlosyrinx sp., Eubela sp., and Phymorhynchus sp., forming the Raphitomidae clade, with high support values. Positive selection analysis showed that a residue located in atp6 (18 S) was identified as the positively selected site with high posterior probabilities, suggesting potential adaption to the cold seep environment. Overall, our data will provide a useful resource on the evolutionary adaptation of cold seep snails for future studies.


Author(s):  
Tianhong Wang ◽  
Zihao Wang ◽  
Ruwei Bai ◽  
Zhijun Yu ◽  
Jingze Liu

Haemaphysalis qinghaiensis is an endemic species and mainly inhabiting in the northwestern plateau of China, which can transmit many zoonotic pathogens and cause great harm to animals. In this study, the complete mitochondrial genome (mitogenome) of H. qinghaiensis was assembled through the Illumina HiSeq platform. The mitogenome was 14,533 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes and 3 noncoding regions (NCRs). The bias towards a high A+T content with 77.65% in mitogenome of H. qinghaiensis. The rearrangement of mitochondrial genes in H. qinghaiensis was consistent with other hard ticks. The phylogenetic analysis based on the concatenation of 13 PCGs from 65 tick mitogenomes showed that the H. qinghaiensis was clustered into a well-supported clade within the Haemaphysalis genus. This is the first complete mitogenome sequence of H. qinghaiensis, which provides a useful reference for understanding of the taxonomic and genetics of ticks.


Zootaxa ◽  
2020 ◽  
Vol 4747 (3) ◽  
pp. 547-561
Author(s):  
QING ZHAO ◽  
GERASIMOS CASSIS ◽  
LING ZHAO ◽  
YIFAN HE ◽  
HUFANG ZHANG ◽  
...  

Zicrona caerulea (Linnaeus, 1758) is a cosmopolitan stink bug species, which belongs to the predatory subfamily Asopinae. In this study, the complete mitochondrial genome of Zicrona caerulea from Shanxi, China was sequenced for the first time, using next generation sequencing. The mitogenome was found to be 15,479 bp in length. It contained 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a typical control region. This research revealed an overall A+T content of 77.14%. All tRNA genes had a clover-leaf structure except for trnS1, which lacks a dihydrouridine (DHU) arm; and for trnV, the DHU arm forms a simple loop. The lengths of rrnS and rrnL were 797 bp and 1,285 bp, respectively. Because of a shortage in tandem repeats, the A+T-rich region was 644 bp in length. Phylogenetic relationships based on these mitogenomes, using Bayesian inference and Maximum likelihood methods, showed that Zicrona caerulea belongs to Asopinae. The monophyly of families of the Pentatomoidea is supported, albeit limited taxon sampling. 


Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1274
Author(s):  
Malte Mader ◽  
Hilke Schroeder ◽  
Thomas Schott ◽  
Katrin Schöning-Stierand ◽  
Ana Paula Leite Montalvão ◽  
...  

European beech, Fagus sylvatica L., is one of the most important and widespread deciduous tree species in Central Europe and is widely managed for its hard wood. The complete DNA sequence of the mitochondrial genome of Fagus sylvatica L. was assembled and annotated based on Illumina MiSeq reads and validated using long reads from nanopore MinION sequencing. The genome assembled into a single DNA sequence of 504,715 bp in length containing 58 genes with predicted function, including 35 protein-coding, 20 tRNA and three rRNA genes. Additionally, 23 putative protein-coding genes were predicted supported by RNA-Seq data. Aiming at the development of taxon-specific mitochondrial genetic markers, the tool SNPtax was developed and applied to select genic SNPs potentially specific for different taxa within the Fagales. Further validation of a small SNP set resulted in the development of four CAPS markers specific for Fagus, Fagaceae, or Fagales, respectively, when considering over 100 individuals from a total of 69 species of deciduous trees and conifers from up to 15 families included in the marker validation. The CAPS marker set is suitable to identify the genus Fagus in DNA samples from tree tissues or wood products, including wood composite products.


2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Li-Shang Dai ◽  
Bao-Jian Zhu ◽  
Yue Zhao ◽  
Cong-Fen Zhang ◽  
Chao-Liang Liu

Abstract In this study, we sequenced the complete mitochondrial genome of Eligma narcissus and compared it with 18 other lepidopteran species. The mitochondrial genome (mitogenome) was a circular molecule of 15,376 bp containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and an adenine (A) + thymine (T) − rich region. The positive AT skew (0.007) indicated the occurrence of more As than Ts. The arrangement of 13 PCGs was similar to that of other sequenced lepidopterans. All PCGs were initiated by ATN codons, except for the cytochrome c oxidase subunit 1 (cox1) gene, which was initiated by the CGA sequence, as observed in other lepidopterans. The results of the codon usage analysis indicated that Asn, Ile, Leu, Tyr and Phe were the five most frequent amino acids. All tRNA genes were shown to be folded into the expected typical cloverleaf structure observed for mitochondrial tRNA genes. Phylogenetic relationships were analyzed based on the nucleotide sequences of 13 PCGs from other insect mitogenomes, which confirmed that E. narcissus is a member of the Noctuidae superfamily.


Parasitology ◽  
2006 ◽  
Vol 134 (5) ◽  
pp. 749-759 ◽  
Author(s):  
J.-K. PARK ◽  
K.-H. KIM ◽  
S. KANG ◽  
H. K. JEON ◽  
J.-H. KIM ◽  
...  

SUMMARYThe complete nucleotide sequence of the mitochondrial genome was determined for the fish tapeworm Diphyllobothrium latum. This genome is 13 608 bp in length and encodes 12 protein-coding genes (but lacks the atp8), 22 transfer RNA (tRNA) and 2 ribosomal RNA (rRNA) genes, corresponding to the gene complement found thus far in other flatworm mitochondrial (mt) DNAs. The gene arrangement of this pseudophyllidean cestode is the same as the 6 cyclophyllidean cestodes characterized to date, with only minor variation in structure among these other genomes; the relative position of trnS2 and trnL1 is switched in Hymenolepis diminuta. Phylogenetic analyses of the concatenated amino acid sequences for 12 protein-coding genes of all complete cestode mtDNAs confirmed taxonomic and previous phylogenetic assessments, with D. latum being a sister taxon to the cyclophyllideans. High nodal support and phylogenetic congruence between different methods suggest that mt genomes may be of utility in resolving ordinal relationships within the cestodes. All species of Diphyllobothrium infect fish-eating vertebrates, and D. latum commonly infects humans through the ingestion of raw, poorly cooked or pickled fish. The complete mitochondrial genome provides a wealth of genetic markers which could be useful for identifying different life-cycle stages and for investigating their population genetics, ecology and epidemiology.


ZooKeys ◽  
2020 ◽  
Vol 925 ◽  
pp. 73-88
Author(s):  
Chaoyi Hu ◽  
Shuaibin Wang ◽  
Bisheng Huang ◽  
Hegang Liu ◽  
Lei Xu ◽  
...  

Scolopendra mutilans L. Koch, 1878 is an important Chinese animal with thousands of years of medicinal history. However, the genomic information of this species is limited, which hinders its further application. Here, the complete mitochondrial genome (mitogenome) of S. mutilans was sequenced and assembled by next-generation sequencing. The genome is 15,011 bp in length, consisting of 13 protein-coding genes (PCGs), 14 tRNA genes, and two rRNA genes. Most PCGs start with the ATN initiation codon, and all PCGs have the conventional stop codons TAA and TAG. The S. mutilans mitogenome revealed nine simple sequence repeats (SSRs), and an obviously lower GC content compared with other seven centipede mitogenomes previously sequenced. After analysis of homologous regions between the eight centipede mitogenomes, the S. mutilans mitogenome further showed clear genomic rearrangements. The phylogenetic analysis of eight centipedes using 13 conserved PCG genes was finally performed. The phylogenetic reconstructions showed Scutigeromorpha as a separate group, and Scolopendromorpha in a sister-group relationship with Lithobiomorpha and Geophilomorpha. Collectively, the S. mutilans mitogenome provided new genomic resources, which will improve its medicinal research and applications in the future.


ZooKeys ◽  
2018 ◽  
Vol 790 ◽  
pp. 127-144 ◽  
Author(s):  
Qiao-Hua Zhang ◽  
Pan Huang ◽  
Bin Chen ◽  
Ting-Jing Li

To date, only one mitochondrial genome (mitogenome) in the Eumeninae has been reported in the world and this is the first report in China. The mitogenome ofO.a.aterrimusis 17 972 bp long, and contains 38 genes, including 13 protein coding genes (PCGs), 23 tRNA genes, two rRNA genes, a long non-coding region (NCR), and a control region (CR). The mitogenome has 79.43% A + T content, its 13 PCGs use ATN as the initiation codon except forcox1using TTG, and nine genes used complete translation termination TAA and four genes have incomplete stop codon T (cox2,cox3,nad4, andcytb). Twenty-two of 23 tRNAs can form the typical cloverleaf secondary structure except fortrnS1. The CR is 1 078 bp long with 84.69% A+T content, comprising 28 bp tandem repeat sequences and 13 bp T-strech. There are two gene rearrangements which are an extratrnM2located betweentrnQandnad2and thetrnL2in the upstream ofnad1. Within all rearrangements of these mitogenomes reported in the family Vespidae, the translocation betweentrnS1andtrnEgenes only appears in Vespinae, and the translocation oftrnYin Polistinae and Vespinae. The absent codons of 13 PCGs in Polistinae are more than those both in Vespinae and Eumeninae in the family Vespidae. The study reports the complete mitogenome ofO.a.aterrimus, compares the characteristics and construct phylogenetic relationships of the mitogenomes in the family Vespidae.


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