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PubMed2026

Mitogenome assembly and phylogenetic relationships of Phalaris arundinacea.

INTRODUCTION: As a perennial herb of Poaceae, Phalaris arundinacea plays key roles in grazing, production, and soil and water conservation because of its well-developed rhizomes and seed dispersal. We assembled and annotated the first mitogenome of P. arundinacea to support evolutionary and taxonomic research. METHODS: We assembled and annotated the first complete mitochondrial genome of P. arundinacea by integrating Illumina short reads with Nanopore long reads via a hybrid assembly strategy. The genome architecture was comprehensively characterized, encompassing codon usage bias, repetitive sequence organization, and inter-organellar genetic exchange with the chloroplast genome. RESULTS AND DISCUSSION: Assembly of the P. arundinacea mitogenome revealed two circular structures with a combined length of 526,717 bp. The genome comprised a set of 37 protein-coding genes (PCGs), 27 tRNAs, and 8 rRNAs, with the rRNA genes exhibiting full assembly (100% coverage). The mitochondrial genome contained 154 forward and 164 palindromic repeats, along with 25 tandem repeats and 124 simple sequence repeats (SSRs). Notably, 102 SSRs were distributed on contig1, predominantly in tetrameric form. Furthermore, 376 RNA editing sites were predicted. A total of 104 fragments were integrated into the mitochondrial genome from the chloroplast, amounting to 55,866 bp of transferred sequence. Finally, phylogenetic analysis of 28 plant mitogenomes placed P. arundinacea closest to species within the genus Poa (P. chaixii and P. pratensis). Comparative analysis of non-synonymous-to-synonymous substitution rate (Ka/Ks) ratios across divergent species revealed that the mitochondrial genome of P. arundinacea underwent stabilizing evolutionary dynamics, characterized by predominant purifying selection with several lineage-specific variations in selective pressure. Our findings support the close phylogenetic relationship between P. arundinacea and species of the genus Poa and provide a reference mitochondrial genome resource for future comparative studies within Phalaris that incorporate broader taxon sampling. These results support deeper phylogenetic investigations of P. arundinacea and facilitate future work on its germplasm characterization and applied use.

Phalaris arundinacea↗
PubMed2026

Phylogenetic position of the enigmatic starfish family Podosphaerasteridae (Asteroidea, Valvatida) with a morphological observation of the skeletal structure by micro-CT.

Background The genus Podosphaeraster comprises seven species, characterised by a distinctive spherical body, all currently known from the seabed at depths below approximately 70 m. Its peculiar morphology has made its phylogenetic placement a subject of ongoing debate. It was initially suggested to be placed in Sphaerasteridae, the same family as fossil species. However, subsequent detailed skeletal analyses of the fossil forms suggested that this similarity was likely due to convergent evolution. Recent molecular analyses have revealed that Valvatida, in which the genus is currently placed, is likely a large polyphyletic group, leaving its taxonomic position still unresolved. New information A detailed examination of the internal skeletal structure of Podosphaeraster toyoshiomaruae, collected from the seas around Japan, was conducted using micro-focus X-ray computed tomography. Concurrently, shotgun sequencing was performed to identify key molecular markers for recent asteroid phylogeny. Additionally, shotgun sequencing determined the complete mitochondrial genome. Despite conservative evolution amongst asteroidean mitochondrial genomes, a translocation of the COX2 gene was revealed, representing the first discovery of a major protein-coding gene translocation within Asteroidea. In the phylogenetic tree, P. toyoshiomaruae was positioned as the most basal lineage within Valvatida. However, the statistical support for this placement was low, potentially due to the long-branch attraction caused by the excessively rapid evolutionary rate. Images reconstructed by micro-CT confirmed the presence of calcified reinforcement in the mesentery and showed its detailed structure for the first time. The mesentery skeleton was found to connect to the V-plate and five pairs of plates, including three kinds of marginal plates. This suggests that the marginal plates of this species may not be homologous with those of other asteroids. Although varying degrees of marginal plate reduction are shared with the order Velatida, we consider this to be a case of convergent evolution. Our phylogenetic analysis indicates a close relationship between P. toyoshiomaruae and Poraniidae (and other Valvatida), all of which possess marginal plates differentiated to varying extents, the homology of which remains uncertain.

Asteroidea↗
PubMed1992

[Mitochondrial disease and complete heart block. Kearns-Sayre syndrome. Description of a case].

Defects of the mitochondrial respiratory chain form a clinically and biochemically heterogeneous group of diseases. Mitochondrial diseases include myopathies and multisystem disorders that are defined either by biochemical abnormalities of the mitochondria or by the presence of "ragged red fibers" in muscle-biopsy specimens stained with modified Gomori's trichrome stain. Several syndromes have been identified. Typical Kearns-Sayre syndrome is a sporadic condition that is characterized by an onset before the age of 20, progressive external ophthalmoplegia, pigmentary retinopathy and cardiac disorders. Mitochondrial DNA deletions were found in patient with Kearns-Sayre syndrome. We report the case of a 33 year-old woman, with neuromuscular syndrome of the Kearns-Sayre type, insulin-sensitive diabetes and complete heart block, who was implanted a pacemaker.

Adult↗
PubMed1977

The complete amino acid seqeunce of mitochondrial asparatate aminotransferase from pig heart.

The complete amino acid sequence of the mitochondrial aspartate aminotransferase from pig heart was determined by analyses of the fragments obtained from tryptic digestion and cyanogen bromide treatment of the protein. The sequence analyzer was useful for establishing the primary structure of the N-terminal portion of the whole protein. There are 401 amino acid residues in the molecule. The sequence was compared with that of the cytoplasmic isozyme, showing 48% homology.

Amino Acid Sequence↗
PubMed1975

Rearrangement of mitochondrial DNA molecules during the differentiation of mitochondria in yeast. I.-Electron microscopic studies of size and shape.

Size and shape of purified mitochondrial DNA was analyzed by electron microscopy as a function of mitochondrial differentiation. The mitochondrial DNA was extracted at fourth growth stages corresponding to different steps of mitochondria repression and depression. It was heterogeneous both in form and length. The size of linear molecules ranged from 1 mu to 25 mu but most of the molecules could be assigned into four Gaussian subpopulations with mean lengths of 2.2 mu to 4.0 mu, 6.0 mu and 10.0 mu. The circular molecules were all open and sized varied from 0.5 mu to 10 mu. Their length repartition was congruent with a logarithmic Gaussian distribution. The relative proportion of the different classes of molecules changed according to the stage of the growth cycle: during the repression most of the mitochondrial DNA molecules were short: the population of 2.2 mu was predominant. The longest linear molecules were observed during derepression where the populations of 4.0 mu and 10.0 mu were only found as well as the highest proportion of circular molecules. At the stationary phase the mitochondrial DNA became short again and the circles disappeared completely. The mitochondrial DNA extracted from a cytoplasmic "petite" was composed of linear and circular molecules. The linear molecules ranged from 0.1 mu to 32 mu and most of them could be assigned to two subpopulations of 1.3 mu and 4.2 mu. The circular molecules which accounted for 11 percent had contour lengths of 0.7 mu and 1.5 mu. The physiological meaning of the change in the relative proportion of different classes of mitochondrial DNA is discussed.

DNA, Circular↗
PubMed1978

Studies on the mitochondrially bound form of rat brain creatine kinase.

1. The development of the total rat brain creatine kinase was studied in brain homogenates. Until approx. 14-15 days after birth, the activity remains less than one-third that of the adult activity (207+/-6 units/g wet wt. s.d.; n=3). Over the next 10 days the activity increases markedly to the adult value and thereafter remains essentially constant. 2. In the adult brain, approx. 5% (11.9+/-2.2 units/g wet wt. s.d.; n=5) of the total creatine kinase is associated with the mitochondrial fraction. This creatine kinase could not be solubilized by sodium acetate solutions of up to 0.8m concentration, whereas 66% of the hexokinase associated with brain mitochondria was released under these conditions. 3. Rat brain mitochondria incubated in the presence of various concentrations of creatine (1, 5 and 10mm) and ADP (100mum) synthesized phosphocreatine at rates of approx. 4.5, 11 and 17.5nmol/min per mg of mitochondrial protein. Atractyloside (50mum) or oligomycin (1.5mug/mg of mitochondrial protein) completely inhibited the synthesis of phosphocreatine. 4. The apparent K(m) and V(max.) values of the mitochondrially bound rat brain creatine kinase were determined in both directions. The V(max.) in the direction of phosphocreatine synthesis is 237nmol/min per mg of mitochondrial protein, with an apparent K(m) for creatine of 1.67mm and for MgATP(2-) of 0.1mm, and in the reverse direction V(max.) is 489nmol/min per mg of mitochondrial protein, with an apparent K(m) for phosphocreatine of 0.4mm and for MgADP(-) of 27mum. 5. The results are discussed with reference to the role that the mitochondrially bound creatine kinase may play in the development of brain energy metabolism.

Acetates↗
PubMed1976

Effects of corticosterone on adrenocorticotrophin-induced mitochondrial differentiation with special reference to 11 beta- and 18-hydroxylation.

The effects of corticosterone in concentrations found in adrenal venous plasma on ACTH-induced changes in cultured cortical cells derived from foetal rat adrenals were studied. Corticosterone at a concentration of 5-7 X 10(-5) mol/l completely inhibited mitochondrial differentiation to fasciculte-like morphology. The same cultures revealed significant inhibition of 11beta- and 18-hydroxylation compared with cultures treated with ACTH only. This was shown by the reduced formation of corticosterone and 18-OH-deoxycorticosterone (48%, P less than 0-001) and simultaneous enhancement of deoxycorticosterone formation (33%, P less than 0-05) from added [4-14C]progesterone. Similar inhibition was observed when dibutyryl cyclic AMP replaced ACTH as an inducer of differentiation. Lower concentrations of corticosterone (1-2 X 10(-5) and 2-4 X 10(-5) mol/l) inhibited ACTH-stimulated formation of corticosterone and 18-OH-deoxycorticosterone from endogenous precursors. The results demonstrate that corticosterone regulates the stage of differentiation in cultured adrenocortical cells. The possible role of corticosterone in the regulation of growth and steroidogenic capacity of the adrenal cortex is discussed.

18-Hydroxydesoxycorticosterone↗
PubMed1977

Activities of mitochondrial enzymes during aerobic synchronous growth of aerobically and anaerobically grown Saccharomyces cerevisiae.

The mitochondrial enzymes cytochrome-c:O2-oxidoreductase (E.C.1.9.3.1), NADH:cytochrome-c-oxidoreductase (E.C.1.6.2.1), NADH: ferricyanide oxidoreductase (E.C.1.6.2.99), L-malate hydrolase (E.C.4.2.1.2) and L-malate:NADH-oxidoreductase (E.C.1.1.3.7) increase their activities during the aerobic synchronous growth of aerobically grown Saccharomyces cerevisiae in discrete steps and only once during the cell cycle. An identical phenomenon was observed during the aerobic synchronous growth of anaerobically grown yeast. The mechanism of completization of mitochondrial membranes is thus likely to be discontinuous and the same during both mitochondrial multiplication and the conversion of promitochondria to fully functioning mitochondria.

Aerobiosis↗
PubMed1977

Relationship of potassium ion transport and ATP synthesis in pea cotyledon mitochondria.

Simultaneous monitoring of ATP synthesis and K+ movements across pea mitochondrial membranes revealed information about the competition of the two processes for mitochondrial energy. In the presence of valinomycin and at low extramitochondrial K+ concentration, ADP could be phosphorylated rapidly. This occurred with a decrease in net potassium ion uptake. At higher external K+ concentrations respiratory energy was unavailable for ATP synthesis and only a portion of added ADP could be phosphorylated within a reasonable time. Magnesium ions were shown to have an inhibitor effect on the K+ uptake, and stimulated a greater rate of ATP synthesis. When valinomycin and ADP were added simultaneously so that phosphorylation of the ADP and enhancement of K+ uptake could complete for mitochondrial energy, K+ uptake was preferred over ATP synthesis.

Adenosine Diphosphate↗
PubMedDate not supplied

Mechanism of carrier-mediated glutamine transport across the inner mitochondrial membrane.

Mersalyl completely inhibits glutamine influx into kidney and liver mitochondria indicating clearly that this process requires the presence of functional thiol groups and probably a specific glutamine carrier. There is a close correlation between the transport of glutamine and the transport of inorganic phosphate. Glutamine crosses mitochondrial membrane as an electroneutral species driven by the concentration gradient. Proton gradient and membrane potential generated by the energization of kidney mitochondria stimulate the influx of glutamine. Glutaminase and glutamine carrier are probably distinct proteins.

Animals↗
PubMedDate not supplied

Cytoplasmic gamma-glutamyltransferase: isolation, product formation and physiological role.

These results establish the existence of a cytoplasmic glutaminase-gamma-glutamyltransferase enzyme as a distinct entity. Its products are ammonia and activated glutamate. Ammonia liberation is obligatory to the utilization of the amide bond energy in forming gamma-glutamyl-PO4. This activated glutamate can then be utilized in the gamma-glutamyl cycle for the synthesis of gamma-glutamylcysteine. The cytoplasmic glutamine utilizing pathway is closely coupled to gamma-glutamyl cycl activity: loading the cycle stimulates increased renal glutamine uptake into this pathway. Consequently, the pathway, stimulated by elevated ADP levels, appears to function as an auxilary source of gamma-glutamyl moieties for the gamma-glutamyl cycle. Although insignificant compared to the mitochondrial pathway's contribution to ammonia production in metabolic acidosis, it is highly significant from the perspective of the Unitary Hypothesis. The existence of this dual system allows the demonstration of a shift in glutamine utilization from predominant cytoplasmic to overwhelming mitochondrial glutamine utilization in metabolic acidosis corresponding to a rise in the NH3/gln ratio from 1.2 to 1.9 and a quantitative recovery of gln carbon as CO2 and glucose. The fact that this shift in pathways is induced by acidosis (through adrenosteroids) and that it represents a 10 to 20 fold activation of the mitochondrial pathway is completely consistent with a glucocorticoid mediated glutamine permeability increase of the inner mitochondrial membrane.

Animals↗
PubMed1977

Subcellular localization of the alterations in phosphatidylinositol metabolism following glucose-induced insulin release from rat pancreatic islets.

The subcellular localization of the incorporation of 2-(3H)-myoinositol into lipids has been studied in isolated pancreatic islets of the rat. The recovery of lipid-bound myoinositol increased with time in the nuclear, mitochondrial, microsomal, and secretory granule fractions. The utilization of a filtration technique for the more complete separation of mitochondrial and secretory granule elements permitted us to show that the recovery of lipid-bound 2-(3H)-myoinositol increased most rapidly in the secretory granule fraction. A 30-minute exposure of prelabeled islets to a stimulatory concentration of D-glucose (3.0 mg./ml.) resulted in a statistically significant decrease in the amount of lipid-bound 2-(3H)-myoinositol that was recovered from the secretory granule fraction (p less than 0.001). In contrast, exposure of islets to the elevated glucose concentration had no statistically significant effect on the recovery of lipid-bound radioactivity from other subcellular fractions. Since the majority of lipid-bound radioactivity associated with the secretory granule fraction could be recovered with the presumptive secretory granule membranes, these data suggest that the hydrolysis of phosphatidylinositol that accompanies glucose-induced insulin secretion from the rat pancreatic islet may be localized to the beta granule and, in particular, to its limiting membrane.

Animals↗
PubMed2023

The complete mitogenome of Paratanakia chii (Cypriniformes; Cyprinidae).

Paratanakia chii is a bitterling fish of the genus Paratanakia, subfamily Acheilognathinae and family Cyprinidae. The mitochondrial DNA sequence of P. chii is reported in this paper. The complete mitochondrial genome of P. chii is 16,575 bp in length, including 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and 1 displacement loop (D-loop). The genome sequence is consistent with those of most other carp. The majority of PCGs have AT- (Met) start codons and TA- end codons. The A + T contents of the genome, PCGs, transfer RNAs (tRNAs), and ribosomal RNAs (rRNAs) are 56.92%, 58.07%, 56.34%, and 54.21%, respectively. Phylogenetic analysis showed that P. chii is most closely related to Tanankia himantegus. These data will benefit relative ecological and phylogenetic studies.

Acheilognathinae↗
PubMed1975

Effects of thiamine deprivation and replacement on the mitochondrion of Polytomella agilis.

Late log-phase cells of Polytomella agilis, grown with or without thiamine, were examined by electron microscopy. The mitochondrial profiles of cells cultivated in the presence of thiamine are relatively few in number and irregular in shape. The inner membranes, randomly dispersed in a light matrix, are elongated, vesicular, or branched in appearance. In vitamin-deficient cells, numerous mitochondrial profiles are evident. They have a regular circular or ovoid appearance. The inner membranes are regularly arrayed in an electron-dense matrix and generally appear elongated. By means of partial 3-dimensional reconstruction of whole cells the appearance of mitochondrial profiles in vitamin-deficient cells can be explained by the increased branching of a single structure. Following transfer of vitamin-deficient cells to complete medium, normal mitochondrial structure is attained by similar to 3 hr. Reduced-minus-oxidized difference spectra of suspensions of normal and vitamin-deficient cells, grown with gentle aeration, were recorded. The concentrations of a- and b-type cytochromes are reduced by 80-90 per cent, and c-type cytochromes are reduced by 40 per cent in thiamine-deficient cells.

Culture Media↗
PubMed1975

Biochemical and cytological studies of mitochondrial development in chloramphenicol-induced rice coleoptiles.

The ultrastructure and respiratory activity of mitochondria in rice coleoptile grown in the presence and in the absence of an inibitor of mitochondrial protein synthesis (chloramphenicol) have been studied. It is shown that during the first 48 h of germination a rapid development of mitochondrial cristae takes place without notable influence of chloramphenicol on biogenesis of mitochondria. But the presence of the inhibitor has a significant effect in the subsequent period (48-144 h): a gradual and almost complete reduction of mitochondrial cristae is observed. These unusual "noncristate" mitochondria, although greatly lacking cytochrome oxidase, have a high respiratory activity. The respiration of "noncristate" mitochondria is resistant to KCN. It is supposed that chloramphenicol-induced rice coleoptile can be used as a new convenient object for studies of the nature of alternative oxidase as well as the biogenesis of mitochondria with cyanide-insensitive respiration.

Carbonyl Cyanide m-Chlorophenyl Hydrazone↗
PubMed1977

[A comparative study of the role of creatine phosphokinase isoenzymes in energy metabolism of skeletal and heart muscle].

It has been shown that the contents of mitochondria and mitochondrial isoenzyme of creatine phosphokinase are almost identical in skeletal and heart muscles. In mitochondria from both types of muscle creatine phosphokinase is functionally coupled to ATP-ADP translocase. This kind of coupling ensures complete conversion of mitochondrial ATP energy into the energy of creatine phosphate and effective control of oxidative phosphorylation by the creatine phosphokinase reaction. It has also been shown that all isoenzymes of creatine phosphokinase from heart and skeletal muscle have very similar kinetic properties. Significant differences have been found to exist between isoenzyme patterns of these muscles and also in distribution of different isoenzymes in the cells. In skeletal muscle cells creatine phosphokinase is present mainly as cytosolic MM isoenzyme; about 6% of total cellular activity is localised also in mitochondria. Due to high activity of cytosolic isoenzyme the total activity of creatine phosphokinase is about three times higher in skeletal muscle than in cardiac muscle. It has been also shown that phosphoenolpyruvate and glucose-6-phosphate do not have any inhibitory effect on creatine phosphokinase.

Animals↗