Physical activity habits prevent psychological distress in female academic students: The multiple mediating role of physical and psychosocial parameters.

Background: Psychological distress is recognised as the most common mental health difficulty in emerging adult (18-to-24-year-old) female academic students. This study aimed to test a novel model positing physical activity habits as a protective factor for psychological distress through the mediating role of physical and psychological parameters. Adherence to the Mediterranean diet and self-reported physical health status were included as physical parameters. Self-reported psychological health status and time spent on leisure activities were the psychological parameters considered. Method: Data were collected between April and May 2021. Correlation analyses and a multiple mediation model were computed on 411 online questionnaires filled out by 18-to-24-year-old female students from the University of blind (Italy). Results: The multiple indirect effects were significant (ß = -0.088; p < 0.001). This means that physical activity habits reduce psychological distress through high adherence to the Mediterranean diet, a good self-assessment of one's physical and psychological health status, and more time spent on leisure activities outdoors, with friends, and with family members. Conclusions: Results show that academic policies should be adopted so as to design physical activity programmes that may improve the students' healthy behaviours and social interactions, which, in turn, mitigate the detrimental effects of psychological distress.

Quercetin inhibits fatty acid and triacylglycerol synthesis in rat-liver cells.

BACKGROUND: Quercetin plays a cardiovascular protective role because of its antioxidant capacity and ability to modulate dyslipidemia. As alterations in hepatic lipid synthesis are crucial to the regulation of serum lipid levels, we investigated the quercetin effect on lipogenesis in rat liver cells. MATERIALS AND METHODS: The effect of quercetin on the rate of synthesis of fatty acids, cholesterol, neutral lipids, phospholipids and very-low-density lipoproteins (VLDL) was investigated in rat hepatocyte suspensions following [1-(14)C]acetate incorporation into these lipid fractions. Enzyme activities of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) as well as diacylglycerol acyltransferase (DGAT) and 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA-R), pace-setting steps of de novo fatty acid, triacylglycerol (TAG) and cholesterol synthesis respectively were assayed in digitonin-permeabilized hepatocytes. RESULTS: Within 30 min of quercetin addition to the hepatocytes, inhibition (IC50 approximately 25 microM) of fatty acid synthesis occurred. A reduction in label incorporation mainly into TAG was observed. Among neosynthesized fatty acids, palmitic acid formation was greatly reduced, suggesting that enzymatic step(s) of de novo fatty synthesis was affected. Only ACC activity was noticeably reduced, but no change in FAS activity was observed. DGAT activity was also inhibited. The decreased intracellular TAG content was paralleled by a reduction in acetate incorporation into VLDL-TAG. Conversely, cholesterol synthesis and HMG-CoA-R were not significantly affected by quercetin. CONCLUSIONS: In hepatocytes from normal rats, the quercetin-induced decrease in both de novo fatty acid and TAG synthesis, with a consequent reduction in VLDL-TAG formation, may represent a potential mechanism contributing to the reported hypotriacylglycerolemic effect of quercetin.

n-6 PUFAs downregulate expression of the tricarboxylate carrier in rat liver by transcriptional and posttranscriptional mechanisms.

The tricarboxylate (citrate) carrier (TCC), a protein of the mitochondrial inner membrane, is an obligatory component of the shuttle system by which mitochondrial acetyl-CoA is transported into the cytosol, where lipogenesis occurs. The aim of this study was to investigate the molecular basis for the regulation of TCC gene expression by a high-fat, n-6 PUFA-enriched diet. Rats received for up to 4 weeks a diet enriched with 15% safflower oil (SO), which is high in linoleic acid (70.4%). We found a gradual decrease of TCC activity and a parallel decline in the abundance of TCC mRNA, the maximum effect occurring after 4 weeks of treatment. At this time, the estimated half-life of TCC mRNA was the same in the hepatocytes from rats on both diets, whereas the transcriptional rate of TCC mRNA, tested by nuclear run-on assay, was reduced by approximately 38% in the rats on the SO-enriched diet. The RNase protection assay showed that the ratio of mature to precursor RNA, measured in the nuclei, decreased with the change to the n-6 PUFA diet. These results suggest that administration of n-6 PUFAs to rats leads to changes not only in the transcriptional rate of the TCC gene but also in the processing of the nuclear precursor for TCC RNA.

Citrate carrier activity and cardiolipin level in eel (Anguilla anguilla) liver mitochondria.

The activity of the tricarboxylate (citrate) carrier has been assayed in intact liver mitochondria from yellow eel (Anguilla anguilla) and compared to that from rat. The eel-citrate carrier specific activity was approximately 1.7-fold higher than that assayed in rat-liver mitochondria. The content of the main mitochondrial phospholipids, phosphatidylethanolamine and phosphatidylcholine, did not show a significant difference between the two species, while in eel a higher cardiolipin level was observed. Fatty acid composition of eel-liver mitochondrial phospholipids was characterised by a large amount of unsaturated fatty acids, dominated by octadecaenoic acid (C(18:1) (n-9)) and docosahexaenoic acid (C(22:6) (n-3)). The cardiolipin fatty acid pattern of eel-liver mitochondria showed, with respect to the rat, a higher C(20:5) (n-3) and C(22:6) (n-3) content and a lower amount of C(18:2) (n-6) and C(20:4) (n-6). A noticeable activity of lipogenic enzymes was also detected in eel liver cytosol. The results of this study suggest that the remarkable activity of the citrate carrier in eel-liver mitochondria can most likely be ascribed to a considerable cardiolipin level. A covariance of citrate carrier and lipogenic enzyme activities was observed.

Covariance of tricarboxylate carrier activity and lipogenesis in liver of polyunsaturated fatty acid (n-6) fed rats.

The mitochondrial tricarboxylate (citrate) carrier plays an important role in hepatic intermediary metabolism because, among other functions, it supplies the cytosol with acetyl units for fatty-acid synthesis. In this study, the effect of polyunsaturated fatty acids (PUFA, n-6) on the function of this mitochondrial transporter and on lipogenic enzyme activities was investigated by feeding rats for 4 weeks with a 15%-fat diet composed of high linoleic safflower oil. Citrate transport was strongly reduced in liver mitochondria isolated from PUFA-treated rats. A reduced transport activity was also observed when solubilized mitochondrial citrate carrier from PUFA-treated rats was reconstituted into liposomes. In the same animals, a decrease of cytosolic lipogenic enzyme activities was observed. These results indicate a coordinated modulation of citrate carrier and of lipogenic enzyme activities by PUFA feeding. Kinetic analysis of the carrier activity showed that only V(max) decreased, whereas K(m) was almost virtually unaffected. The PUFA-mediated effect is most likely due to the reduced mRNA level and lower content of the citrate carrier protein observed in the safflower oil-fed rats.

Fatty acid chain elongation synthesis in eel (Anguilla anguilla) liver mitochondria.

The properties of fatty acid chain elongation synthesis have been investigated in liver mitochondria of the European eel (Anguilla anguilla). The incorporation of [1-(14)C]acetyl-CoA into fatty acids shows a specific activity of 0.43+/-0.05 nmol/min x mg protein (n=6), which is more than twice higher than that previously reported in rat liver mitochondria. Label incorporation into fatty acids was, in mitochondria disrupted by freezing and thawing, much higher than in intact organelles thus suggesting a probable localization of this pathway inside mitochondria. Only a negligible acetyl-CoA incorporation into fatty acids occurs in the absence of ATP, Mg2+ or reduced pyridine nucleotides; NADH alone seems to be as effective as NADH + NADPH as a hydrogen donor for the reducing steps. CoASH, without effect up to 10 microM, showed a strong inhibition at higher concentrations. From the ratio of total radioactivity and radioactivity in carboxyl carbon it can be inferred that in eel-liver mitochondria only chain elongation of preexisting fatty acids occurs. A significant fatty acid chain elongation activity is also present when, instead of acetyl-CoA, [2-(14)C]malonyl-CoA is used as a carbon unit donor. Moreover, the synthesized fatty acids were actively incorporated into phopholipids, mainly phosphatidylcholine, phosphatidylethanolamine and sphyngomyelin.

Oleic acid inhibits endothelial activation : A direct vascular antiatherogenic mechanism of a nutritional component in the mediterranean diet.

Because oleic acid is implicated in the antiatherogenic effects attributed to the Mediterranean diet, we investigated whether this fatty acid can modulate endothelial activation, ie, the concerted expression of gene products involved in leukocyte recruitment and early atherogenesis. We incubated sodium oleate with human umbilical vein endothelial cells for 0 to 72 hours, followed by coincubation of oleate with human recombinant tumor necrosis factor, interleukin (IL)-1alpha, IL-1beta, IL-4, Escherichia coli lipopolysaccharide (LPS), or phorbol 12-myristate 13-acetate for a further 6 to 24 hours. The endothelial expression of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and intercellular adhesion molecule-1 was monitored by cell surface enzyme immunoassays or flow cytometry, and steady-state levels of VCAM-1 mRNA were assessed by Northern blot analysis. At 10 to 100 micromol/L for >24 hours, oleate inhibited the expression of all adhesion molecules tested. After a 72-hour incubation with oleate and a further 16-hour incubation with oleate plus 1 microg/mL LPS, VCAM-1 expression was reduced by >40% compared with control. Adhesion of monocytoid U937 cells to LPS-treated endothelial cells was reduced concomitantly. Oleate also produced a quantitatively similar reduction of VCAM-1 mRNA levels on Northern blot analysis and inhibited nuclear factor-kappaB activation on electrophoretic mobility shift assays. Incubation of endothelial cells with oleate for 72 hours decreased the relative proportions of saturated (palmitic and stearic) acids in total cell lipids and increased the proportions of oleate in total cell lipids without significantly changing the relative proportions of polyunsaturated fatty acids. Although less potent than polyunsaturated fatty acids in inhibiting endothelial activation, oleic acid may contribute to the prevention of atherogenesis through selective displacement of saturated fatty acids in cell membrane phospholipids and a consequent modulation of gene expression for molecules involved in monocyte recruitment.

Purification and characterization of the tricarboxylate carrier from eel liver mitochondria.

The tricarboxylate carrier from eel (Anguilla anguilla) liver mitochondria was solubilized with Triton X-100 and purified by sequential chromatography on hydroxyapatite and Matrex Gel Blue B. On SDS-polyacrylamide gel electrophoresis, the purified fraction showed a single polypeptide band with an apparent molecular mass of 30.4 kDa. When reconstituted into liposomes, the tricarboxylate transport protein catalyzed a very active 1,2,3-benzenetricarboxylate-sensitive citrate/citrate exchange. It was purified 641-fold with a recovery of 13.3% and a protein yield of 0.02% with respect to the mitochondrial extract. The properties of the reconstituted carrier, i.e., requirement for a counteranion, substrate specificity and inhibitor sensitivity, were similar to those of the tricarboxylate carrier purified from rat liver mitochondria. These studies provide the first information on the mitochondrial tricarboxylate transport protein of a fish.

Partial purification and reconstitution of the tricarboxylate carrier from eel liver mitochondria.

The tricarboxylate carrier of the inner membrane of eel liver mitochondria has been solubilized with Triton X-100 and partially purified by chromatography of the mitochondrial extract on dry hydroxyapatite. The purified fraction has been reconstituted into liposomes and functionally analyzed. The reconstituted carrier protein catalyzed a 1,2,3-benzenetricarboxylate-sensitive citrate uptake in liposomes. The substrate specificity and the inhibitor sensitivity of the tricarboxylate carrier are similar to those previously determined for the same protein of mammalian mitochondria.

GTG as translation initiation codon in the apocytochrome b gene of sunflower mitochondria.

Sunflower mitochondrial DNA contains a single copy of the cob gene. The gene begins with the unusual GTG initiation codon and lies in a transcription unit having a different organization with respect to that common to the other six known sequences from plant species which include both monocotyledons and dicotyledons.

Identification and mapping of trnI, trnE and trnfM genes in the sunflower mitochondrial genome.

Three sunflower mitochondrial HindIII restriction fragments containing the tRNA genes trnI, trnE and trnfM have been sequenced. The genes are present in single copy on the whole genome and are transcribed. Hybridization experiments and sequence analysis of the HindIII fragments allowed the precise mapping and orientation of each gene on the sunflower mitochondrial genome.

A tRNA(Val) (GAC) gene of chloroplast origin in sunflower mitochondria is not transcribed.

A tRNA(Val) (GAC) gene is located in opposite orientation 552 nucleotides (nt) down-stream of the cytochrome oxidase subunit III (coxIII) gene in sunflower mitochondria. The comparison with the homologous chloroplast DNA revealed that the tRNA(Val) gene is part of a 417 nucleotides DNA insertion of chloroplast origin in the mitochondrial genome. No tRNA(Val) is encoded in monocot mitochondrial DNA (mtDNA), whereas two tRNA(Val) species are coded for by potato mtDNA. The mitochondrial genomes of different plant species thus seem to encode unique sets of tRNAs and must thus be competent in importing the missing differing sets of tRNAs.

Physical and gene organization of mitochondrial DNA in fertile and male sterile sunflower. CMS-associated alterations in structure and transcription of the atpA gene.

To study the molecular basis of cytoplasmic male sterility (CMS) in sunflower (Helianthus annuus), we compared the physical organization and transcriptional properties of mitochondrial DNAs (mtDNAs) from isonuclear fertile and CMS lines. Mapping studies revealed much greater similarity between the two mtDNAs than in previous comparisons of fertile and CMS lines from other plant species. The two sunflower mtDNAs 1) are nearly identical in size (300 kb and 305 kb); 2) contain the same 12 kb recombination repeat and associated tripartite structure; 3) have the same dispersed distribution of mitochondrial genes and chloroplast DNA-homologous sequences; 4) are greater than 99.9% identical in primary sequence; and 5) are colinear over a contiguous region encompassing 94% of the genome. Detectable alterations are limited to a 17 kb region of the genome and reflect as few as two mutations--a 12 kb inversion and a 5 kb insertion/deletion. One endpoint of both rearrangements is located within or near atpA, which is also the only mitochondrial gene whose transcripts differ between the fertile and CMS lines. Furthermore, a nuclear gene that restores fertility to CMS plants specifically influences the pattern of atpA transcripts. Rearrangements at the atpA locus may, therefore, be responsible for CMS in sunflower.

Stimulation of protein synthesis in isolated mammalian mitochondria by a factor in the cytosol.

Dialyzed rat liver cytosol possesses the ability to stimulate the incorporation of [35S]-methionine into mitochondrial proteins. The addition of dialyzed cytosol stimulates sevenfold the rate of protein synthesis by isolated mitochondria after 10 minutes incubation and the extent of this stimulation increases with the time. Various control experiments indicate that the effect is not artifactual nor does it appear to be brought about by GDP or GTP.