Members Of Tricarboxylic Acid Cycle Research Articles

Comparative genomic analysis of the tricarboxylic acid cycle members in four Solanaceae vegetable crops and expression pattern analysis in Solanum tuberosum

BackgroundThe tricarboxylic acid (TCA) cycle is crucial for energy supply in animal, plant, and microbial cells. It is not only the main pathway of carbohydrate catabolism but also the final pathway of lipid and protein catabolism. Some TCA genes have been found to play important roles in the growth and development of tomato and potato, but no comprehensive study of TCA cycle genes in Solanaceae crops has been reported.ResultsIn this study, we analyzed TCA cycle genes in four important Solanaceae vegetable crops (potato (Solanum tuberosum), tomato (Solanum lycopersicum), eggplant (Solanum melongena), and pepper (Capsicum annuum)) based on comparative genomics. The four Solanaceae crops had a total of 180 TCA cycle genes: 43 in potato, 44 in tomato, 40 in eggplant, and 53 in pepper. Phylogenetic analysis, collinearity analysis, and tissue expression patterns revealed the conservation of and differences in TCA cycle genes between the four Solanaceae crops and found that there were unique subgroup members in Solanaceae crops that were independent of Arabidopsis genes. The expression analysis of potato TCA cycle genes showed that (1) they were widely expressed in various tissues, and some transcripts like Soltu.DM.01G003320.1(SCoAL) and Soltu.DM.04G021520.1 (SDH) mainly accumulate in vegetative organs, and some transcripts such as Soltu.DM.12G005620.3 (SDH) and Soltu.DM.02G007400.4 (MDH) are preferentially expressed in reproductive organs; (2) several transcripts can be significantly induced by hormones, such as Soltu.DM.08G023870.2 (IDH) and Soltu.DM.06G029290.1 (SDH) under ABA treatment, and Soltu.DM.07G021850.2 (CSY) and Soltu.DM.09G026740.1 (MDH) under BAP treatment, and Soltu.DM.02G000940.1 (IDH) and Soltu.DM.01G031350.4 (MDH) under GA treatment; (3) Soltu.DM.11G024650.1 (SDH) can be upregulated by the three disease resistance inducers including Phytophthora infestans, acibenzolar-S-methyl (BTH), and DL-β-amino-n-butyric acid (BABA); and (4) the levels of Soltu.DM.01G045790.1 (MDH), Soltu.DM.01G028520.3 (CSY), and Soltu.DM.12G028700.1 (CSY) can be activated by both NaCl and mannitol. The subcellular localization results of three potato citrate synthases showed that Soltu.DM.01G028520.3 was localized in mitochondria, while Soltu.DM.12G028700.1 and Soltu.DM.07G021850.1 were localized in the cytoplasm.ConclusionsThis study provides a scientific foundation for the comprehensive understanding and functional studies of TCA cycle genes in Solanaceae crops and reveals their potential roles in potato growth, development, and stress response.

The influence of AICAR - direct activator of AMP-activated protein kinase (AMPK) - on liver proteome in apoE-knockout mice

There is a growing body of evidence that altered functioning of apoE may aggravate cellular energy homeostasis and stress response, leading to oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress and inflammation, leading to hypercholesterolemia, dyslipidemia, liver steatosis and neurodegeneration. One of the key cellular responses to mitochondria and ER-stress related processes and cellular energy imbalance is AMP-activated protein kinase (AMPK), considered as a cellular master energy sensor and critical regulator of mitochondrial homeostasis.The aim of our study was to use differential proteomics and transcriptomics approach to elucidate the effect of direct AMPK activator AICAR on liver proteome in apoE−/− mice – experimental model of atherosclerosis and moderate nonalcoholic steatosis. We applied Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) labeling and two-dimensional chromatography coupled with mass spectrometry (2DLC-MS/MS) MudPIT strategy, as well as RT-PCR to investigate the changes in mitochondrial and cytosolic proteins and transcripts expression in 6-month old AICAR-treated apoE−/−.AICAR elicited induction of proteins related to mitochondrial β-oxidation, protein degradation and energy producing pathways (i.a. tricarboxylic acid cycle members and mitochondrial adenylate kinase 2). On the other hand, AICAR repressed inflammatory and pro-apoptotic markers in the apoE−/− mice liver, alongside reduction in several peroxisomal proteins, possibly suggesting induction of anti-oxidative pexophagy.

Taxonomy, chemodiversity, and chemoconsistency of Aspergillus, Penicillium, and Talaromyces species

Aspergillus, Penicillium, and Talaromyces are among the most chemically inventive of all fungi, producing a wide array of secondary metabolites (exometabolites). The three genera are holophyletic in a cladistic sense and polythetic classes in an anagenetic or functional sense, and contain 344, 354, and 88 species, respectively. New developments in classification, cladification, and nomenclature have meant that the species, series, and sections suggested are natural groups that share many extrolites, including exometabolites, exoproteins, exocarbohydrates, and exolipids in addition to morphological features. The number of exometabolites reported from these species is very large, and genome sequencing projects have shown that a large number of additional exometabolites may be expressed, given the right conditions (“cryptic” gene clusters for exometabolites). The exometabolites are biosynthesized via shikimic acid, tricarboxylic acid cycle members, nucleotides, carbohydrates or as polyketides, non-ribosomal peptides, terpenes, or mixtures of those. The gene clusters coding for these compounds contain genes for the biosynthetic building blocks, the linking of these building blocks, tailoring enzymes, resistance for own products, and exporters. Species within a series or section in Aspergillus, Penicillium, and Talaromyces have many exometabolites in common, seemingly acquired by cladogenesis, but some the gene clusters for autapomorphic exometabolites may have been acquired by horizontal gene transfer. Despite genome sequencing efforts, and the many breakthroughs these will give, it is obvious that epigenetic factors play a large role in evolution and function of chemodiversity, and better methods for characterizing the epigenome are needed. Most of the individual species of the three genera produce a consistent and characteristic profile of exometabolites, but growth medium variations, stimulation by exometabolites from other species, and variations in abiotic intrinsic and extrinsic environmental factors such as pH, temperature, redox potential, and water activity will add significantly to the number of biosynthetic families expressed in anyone species. An example of the shared exometabolites in a natural group such as Aspergillus section Circumdati series Circumdati is that most, but not all species produce penicillic acids, aspyrones, neoaspergillic acids, xanthomegnins, melleins, aspergamides, circumdatins, and ochratoxins, in different combinations.

Expression of Pyruvate Carboxylase in Cultured Oligodendroglial, Microglial and Ependymal Cells

The mitochondrial enzyme, pyruvate carboxylase (PC; EC 6.4.1.1) is considered to play a significant role in the intermediary metabolism of neural tissue. PC-catalyzed carboxylation of pyruvate to oxaloacetate is a major anaplerotic reaction in brain. Anaplerosis is essential for homeostasis of the members of the tricarboxylic acid (TCA) cycle. Several biochemical pathways rely on withdrawing TCA cycle members. Prominent among these are biosynthesis of fatty acids and of non-essential amino acids such as aspartate, asparagine, glutamate and glutamine, gluconeogenesis, glycogen synthesis, and regeneration of NADPH. The expression of PC in brain has already been described and assigned to astrocytes. Since pyruvate carboxylase deficiency is associated with malformations of the brain, e.g., inadequate development of the corpus callosum and the lack of myelination, one can hypothesize that PC may be expressed also in glial cells other than astrocytes. Therefore, the expression of PC was investigated in cultured oligodendroglial, microglial, and ependymal cells. As assessed by RT-PCR, all these cultures contain PC mRNA. This mRNA is generated in a transcription process that is regulated by the "distal class" of promoters of the PC gene. The expression of PC among cultured glial cells was studied with a rabbit antiserum by immunoblotting and immunocytochemistry. The results indicate that PC is not only expressed in cultured astroglial cells but also in cultured oligodendrocytes, microglial cells, and ependymocytes. It appears that the intermediary metabolism of these cells includes the anaplerotic action of PC as well as possibly also functions of the enzyme in biosynthetic pathways and the provision of NADPH for defense against reactive oxygen species.

Respiration during Postharvest Development of Soursop Fruit, Annona muricata L

Fruit of soursop, Annona muricata L., showed increased CO(2) production 2 days after harvest, preceding the respiratory increase that coincided with autocatalytic ethylene evolution and other ripening phenomena. Experiments to alter gas exchange patterns of postharvest fruit parts and tissue cylinders had little success.The respiratory quotient of tissue discs was near unity throughout development. 2,4-Dinitrophenol uncoupled respiration more effectively than carbonylcyanide m-chlorophenylhydrazone; 0.4 millimolar KCN stimulated, 4 millimolar salicylhydroxamic acid slightly inhibited, and their combination strongly inhibited respiration, as did 10 millimolar NaN(3). Tricarboxylic acid cycle members and ascorbate were more effective substrates than sugars, but acetate and glutarate strongly inhibited.Disc respiration showed the same early peak as whole fruit respiration; this peak is thus an inherent characteristic of postharvest development and cannot be ascribed to differences between ovaries of the aggregatetype fruit. The capacity of the respiratory apparatus did not change during this preclimacteric peak, but the contents of rate-limiting malate and citrate increased after harvest.It is concluded that the preclimacteric rise in CO(2) evolution reflects increased mitochondrial respiration because of enhanced supply of carboxylates as a substrate, probably induced by detachment from the tree. The second rise corresponds with the respiration during ripening of other climacteric fruits.

INFLUENCES OF RELATED SUBSTANCES OF TRICARBOXYLIC ACID CYCLE UPON PARADOXICAL SLEEP

Investigations into the influences of precursors, members, and inhibitors of the citric acid cycle upon the sleep patterns were carried out in the rabbit with chronically implanted electrodes. The effects of these substances were compared before and after the pre-collicular transection.EMGs were recorded from m. trapezius-pars cervicalis and m. scutuloauricularis superior, EEGs from the frontal cortex, olfactory bulb, and dorsal hippocampus. Changes of the duration and latency of the firstly appeared signs of the paradoxical sleep (PS) after injection of such substances into the aural vein, were adopted as criteria of the facilitatory or inhibitory effects of the substances upon the PS. The results are as follows:A. In the decerebrate animal: 1) the latency of 31-190sec. and the duration of 50-470sec. are characteristic of the PS evoked by administering glucose-(10-30mg), and lactic acid (1.0-2.0mg), and pyruvic acid (1.0-2.0mg). 2) administration of 0.8-3.0mg of the members of the tricarboxylic acid cycle evoked the PS with latency of 20-270sec. and duration of 30-470sec. 3) spontaneous paradoxical sleep phase was not observed for more than 4 hours after the administration of fluoroacetate (0, 4-1.0mg); for 2 hours or more after the administration of malonic acid (1.0-2.0mg). Even if by co-administration of the inhibitors together with the precursors or the members of tricarboxylic acid cycle in gram equivalent, the PS was blocked. 4) after administering the short chain fatty acids (from C2 to C6; 0.6-1.2mg), acetoacetate (1.0-2.0mg) or acetone (0.8-1.2mg) the PS appeared with latency of 21-345sec. and duration of 20-487sec. 5) injection of DPNH (0.7-0.9mg) exercised a marked facilitatory effect upon the evocation of PS with 20-75 seconds latency and 180-960 seconds duration, whereas DPN, TPN or TPNH had no marked facilitating effect, but not produced inhibitory effect. 6) 2, 4-dinitrophenol (0.5-1.5mg) and 2, 3-dimercaptopropanol (0.7-1.0mg) produced neither facilitatory nor inhibitory effect.B. In the intact rabbit, after administration of such precursors and members of the tricarboxylic acid cycle and DPNH, the PS was evoked as in the precollicular animal. However, the latency was longer than in the pre-collicular animal, while the duration was shorter. The PS threshold to direct electrical. stimulation of the septum or the hypothalamus decreased by 40-70 per cent of the control after injection of these substances. No appreciable change in the total amount of PS episodes was revealed following administration of 2, 4-dinitrophenol (0.5-1.5mg) or 2, 3-dimercaptopropanol (0.7-1.0mg), but an increased amount of total PS for 4 hours after administration of the precursors and the members of tricarboxylic acid cycle, and such coenzyme in respiratory chain as DPNH was observed. On the other hand, the appearance of PS was blocked by administration of fluoroacetate (0.4-1.0 mg) or malonic acid (1.0-2.0mg) just as in the case of the supracollicular transected rabbit.C. In the control experiments of the intact animal, 0.2-0.3ml. of distilled water or physiological saline was administered and the PS appeared after the injection with the lapse of 22min. 30sec. to 58min. 50sec. except for one case with 19min. 10sec. After the transection it took 8min. to 30min. before the PS appearance.