Spliced Leader RNAs, Mitochondrial Gene Frameshifts and Multi-Protein Phylogeny Expand Support for the Genus Perkinsus as a Unique Group of Alveolates

Mitochondria are membrane organelles present in almost all eukaryotic cells. In addition to their well-known role in energy production, mitochondria regulate central cellular processes, including calcium homeostasis, Reactive Oxygen Species (ROS) generation, cell death, thermogenesis, and biosynthesis of lipids, nucleic acids, and steroid hormones. Glucocorticoids (GCs) regulate the mitochondrially encoded oxidative phosphorylation gene expression and mitochondrial energy metabolism. The identification of Glucocorticoid Response Elements (GREs) in mitochondrial sequences and the detection of Glucocorticoid Receptor (GR) in mitochondria of different cell types gave support to hypothesis that mitochondrial GR directly regulates mitochondrial gene expression. Numerous studies have revealed changes in mitochondrial gene expression alongside with GR import/export in mitochondria, confirming the direct effects of GCs on mitochondrial genome. Further evidence has made clear that mitochondrial GR is involved in mitochondrial function and apoptosis-mediated processes, through interacting or altering the distribution of Bcl2 family members. Even though its exact translocation mechanisms remain unknown, data have shown that GR chaperones (Hsp70/90, Bag-1, FKBP51), the anti-apoptotic protein Bcl-2, the HDAC6- mediated deacetylation and the outer mitochondrial translocation complexes (Tom complexes) co-ordinate GR mitochondrial trafficking. A role of mitochondrial GR in stress and depression as well as in lung and hepatic inflammation has also been demonstrated.

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Mitochondrial Mistranslation in Brain Provokes a Metabolic Response Which Mitigates the Age-Associated Decline in Mitochondrial Gene Expression

International Journal of Molecular Sciences ◽

10.3390/ijms22052746 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2746

Author(s):

Dimitri Shcherbakov ◽

Reda Juskeviciene ◽

Adrián Cortés Sanchón ◽

Margarita Brilkova ◽

Hubert Rehrauer ◽

...

Keyword(s):

Gene Expression ◽

Metabolic Response ◽

Mitochondrial Gene ◽

Tca Cycle ◽

Brain Mitochondria ◽

Mitochondrial Gene Expression ◽

Rna Seq ◽

The Tca Cycle ◽

Neurological Phenotype

Mitochondrial misreading, conferred by mutation V338Y in mitoribosomal protein Mrps5, in-vivo is associated with a subtle neurological phenotype. Brain mitochondria of homozygous knock-in mutant Mrps5V338Y/V338Y mice show decreased oxygen consumption and reduced ATP levels. Using a combination of unbiased RNA-Seq with untargeted metabolomics, we here demonstrate a concerted response, which alleviates the impaired functionality of OXPHOS complexes in Mrps5 mutant mice. This concerted response mitigates the age-associated decline in mitochondrial gene expression and compensates for impaired respiration by transcriptional upregulation of OXPHOS components together with anaplerotic replenishment of the TCA cycle (pyruvate, 2-ketoglutarate).

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Evolution of Sex Chromosome Heteromorphy in Geographic Populations of the Japanese Tago’s Brown Frog Complex

Cytogenetic and Genome Research ◽

10.1159/000512964 ◽

2021 ◽

pp. 1-9

Author(s):

Chiao Kuwana ◽

Hiroyuki Fujita ◽

Masataka Tagami ◽

Takanori Matsuo ◽

Ikuo Miura

Keyword(s):

Sex Chromosomes ◽

Sex Chromosome ◽

Mitochondrial Gene ◽

Population Level ◽

Chromosome 7 ◽

Geographic Population ◽

Geographic Populations ◽

Western Japan ◽

Brown Frog ◽

Eastern Japan

The sex chromosomes of most anuran amphibians are characterized by homomorphy in both sexes, and evolution to heteromorphy rarely occurs at the species or geographic population level. Here, we report sex chromosome heteromorphy in geographic populations of the Japanese Tago’s brown frog complex (2n = 26), comprising Rana sakuraii and R. tagoi. The sex chromosomes of R. sakuraii from the populations in western Japan were homomorphic in both sexes, whereas chromosome 7 from the populations in eastern Japan were heteromorphic in males. Chromosome 7 of R. tagoi, which is distributed close to R. sakuraii in eastern Japan, was highly similar in morphology to the Y chromosome of R. sakuraii. Based on this and on mitochondrial gene sequence analysis, we hypothesize that in the R. sakuraii populations from eastern Japan the XY heteromorphic sex chromosome system was established by the introduction of chromosome 7 from R. tagoi via interspecies hybridization. In contrast, chromosome 13 of R. tagoi from the 2 large islands in western Japan, Shikoku and Kyushu, showed a heteromorphic pattern of constitutive heterochromatin distribution in males, while this pattern was homomorphic in females. Our study reveals that sex chromosome heteromorphy evolved independently at the geographic lineage level in this species complex.

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A juvenile Tristan albatross (Diomedea dabbenena) on land at the Crozet Islands

Polar Biology ◽

10.1007/s00300-020-02786-0 ◽

2020 ◽

Author(s):

Alexander L. Bond ◽

Christopher Taylor ◽

David Kinchin-Smith ◽

Derren Fox ◽

Emma Witcutt ◽

...

Keyword(s):

Atlantic Ocean ◽

Cytochrome B ◽

Adult Male ◽

Mitochondrial Gene ◽

Small Population ◽

South Atlantic ◽

South Atlantic Ocean ◽

Tristan Da Cunha ◽

Gough Island ◽

Dispersal Events

AbstractAlbatrosses and other seabirds are generally highly philopatric, returning to natal colonies when they achieve breeding age. This is not universal, however, and cases of extraordinary vagrancy are rare. The Tristan Albatross (Diomedea dabbenena) breeds on Gough Island in the South Atlantic Ocean, with a small population on Inaccessible Island, Tristan da Cunha, ca 380 km away. In 2015, we observed an adult male albatross in Gonydale, Gough Island, which had been ringed on Ile de la Possession, Crozet Islands in 2009 when it was assumed to be an immature Wandering Albatross (D. exulans). We sequenced 1109 bp of the cytochrome b mitochondrial gene from this bird, and confirmed it to be a Tristan Albatross, meaning its presence on Crozet 6 years previous, and nearly 5000 km away, was a case of prospecting behaviour in a heterospecific colony. Given the challenges in identifying immature Diomedea albatrosses, such dispersal events may be more common than thought previously.

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