Accumulation Of Arachidonic Acid Research Articles

Inhibiting arachidonic acid generation mitigates aging-induced hyperinsulinemia and insulin resistance in mice

BackgroundAging-related type 2 diabetes (T2DM) is characterized by hyperinsulinemia, insulin resistance, and β-cell dysfunction. However, the underlying molecular mechanisms remain to be unclear. MethodsWe conducted non-targeted metabolomics to compare human serum samples from young adults (YA), elderly adults (EA), and elderly adults with diabetes (EA+DM) of Chinese population. Adult mice and aged mice were intragastrically administered with varespladib every day for two weeks and metabolic characteristics were monitored. Serum levels of arachidonic acid, insulin, and C-peptide, as well as serum activity of secretory phospholipase A2 (sPLA2) were detected in mice. Mouse islet perfusion assays were used to assess insulin secretion ability. Phosphorylated AKT levels were measured to evaluate insulin sensitivities of peripheral tissues in mice. ResultsNon-targeted metabolomics analysis of human serum samples revealed differential metabolic signatures among the YA, EA, and EA+DM groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed significant enhancement of arachidonic acid metabolism and glycerophospholipid metabolism in the EA group compared with the YA group. Further analysis identified two metabolic fluxes that favored the accumulation of arachidonic acid in the elderly. Increased levels of arachidonic acid were also confirmed in aged mice with hyperinsulinemia and insulin resistance, together with subsequent glucose intolerance. Conversely, inhibiting the generation of arachidonic acid with varespladib, an inhibitor of sPLA2, reduced aging-associated diabetes by improving hyperinsulinemia and hepatic insulin resistance in aged mice but not in adult mice. Islet perfusion assays also showed that varespladib treatment suppressed the enhanced insulin secretion observed in aged islets. ConclusionsCollectively, our findings uncover that arachidonic acid serves as a metabolic hub in Chinese elderly population. Our results also suggest that arachidonic acid plays a fundamental role in regulating β-cell function during aging and point to a novel therapy for aging-associated diabetes.

Interactive Effects of Ceftriaxone and Chitosan Immobilization on the Production of Arachidonic Acid by and the Microbiome of the Chlorophyte Lobosphaera sp. IPPAS C-2047.

Pharmaceuticals including antibiotics are among the hazardous micropollutants (HMP) of the environment. Incomplete degradation of the HMP leads to their persistence in water bodies causing a plethora of deleterious effects. Conventional wastewater treatment cannot remove HMP completely and a promising alternative comprises biotechnologies based on microalgae. The use of immobilized microalgae in environmental biotechnology is advantageous since immobilized cultures allow the recycling of the microalgal cells, support higher cell densities, and boost tolerance of microalgae to stresses including HMP. Here, we report on a comparative study of HMP (exemplified by the antibiotic ceftriaxone, CTA) removal by suspended and chitosan-immobilized cells of Lobosphaera sp. IPPAS C-2047 in flasks and in a column bioreactor. The removal of CTA added in the concentration of 20 mg/L was as high as 65% (in the flasks) or 85% (in the bioreactor). The adsorption on the carrier and abiotic oxidation were the main processes contributing 65-70% to the total CTA removal, while both suspended and immobilized cells took up 25-30% of CTA. Neither the immobilization nor CTA affected the accumulation of arachidonic acid (ARA) by Lobosphaera sp. during bioreactor tests but the subsequent nitrogen deprivation increased ARA accumulation 2.5 and 1.7 times in the suspended and chitosan-immobilized microalgae, respectively. The study of the Lobosphaera sp. microbiome revealed that the immobilization of chitosan rather than the CTA exposure was the main factor displacing the taxonomic composition of the microbiome. The possibility and limitations of the use of chitosan-immobilized Lobosphaera sp. IPPAS C-2047 for HMP removal coupled with the production of valuable long-chain polyunsaturated fatty acids is discussed.

Integration analysis of metabolome and transcriptome reveals the effect of arachidonic acid on hemorrhagic anovulatory follicles in jennies

Compared with other livestock, fertility is low in jennies. Although the majority of jennies shows normal ovulation throughout the year, some jennies display hemorrhagic anovulatory follicles (HAF) in the middle of the winter or summer. Based on our previous results (https://doi.org/10.1111/rda.13883), this research was carried out in from November to January of the next year. In experiment 1, a total of 24 Yangyuan jennies (4∼8 years old) were included, with half of them showing normal preovulatory follicles (control group, Con-G) while the other half had HAF ad diagnosed by transrectal ultrasound (HAF-G). The content of the preovulatory follicle or HAF was collected from each jenny by ultrasound-guided ovum pick-up. The follicular fluid (FF) and granulosa cells (GCs) were used for omics analysis. The results of metabolomics analysis showed that the level of arachidonic acid (AA) was significantly increased in HAF-G (P < 0.05). According to transcriptomics results, the mRNA levels of arachidonate 5-lipoxygenase gene (ALOX5) was significantly increased (P < 0.05) while the level of cytochrome P450 family 2 subfamily J member 2 gene (CYP2J2) was significantly decreased in HAF-G (P < 0.05). However, there was no significant difference between the two groups in the expressionsof prostaglandin-endoperoxide synthase 1 gene (COX1) and COX2 (P > 0.05). Meanwhile, the expressions of FSHR, LHCGR and CYP19A1 were significantly decreased in the HAF-G compared with the Con-G (P < 0.05). In order to pursue the molecular mechanism of AA regulating the functions of granulosa cell, the experiment two was carried out. The mice GCs from antral follicles were cultured in media supplemented with 0, 50 μM or 100 μM AA respectively, and both of cell viability and some genes’ expressions were assayed. The results demonstrate that the survival of GCs and mRNA expressions of FSHR and LHCGR were higher in 50 μM AA group than the control group (P < 0.05). However, when the AA concentration was increased to 100 μM in the medium, the survival rates and expression of FSHR and LHCGR were decreased in comparison to the control group (P < 0.05). Moreover, 100 μM AA increased the expression of ALOX5 and decreased the expression of CYP2J2 compared with 50 μM AA, which was similar to GCs from HAF of jennies. In conclusion, the occurrence of HAF in jennies may be related to the accumulation of AA in follicular fluid of the preovulatory follicles which caused abnormal expression of FSHR, LHCGR and ALOX5 on GCs leading to anovulation and HAF.

Abstract 1250: Aberrant polyunsaturated fatty acids desaturation impairs survival and anti-tumor immunity of tumor resident memory CD8+ T cell in hepatocellular carcinoma

Abstract Background &amp; Aim: Aberrant polyunsaturated fatty acids (PUFAs) metabolism is closely associated with the immunosuppressive tumor microenvironment (TME). Tissue-resident memory T cell (Trm) plays a central role against solid tumors, including HCC, depending on the uptake of exogenous fatty acids to maintain survival and anti-tumor immunity. Here we aimed to explore the potential interaction in TME between HCC-derived PUFAs and Trm function in a series of integrated clinical, basic and translational studies. Methods: Tissue interstitial fluids (TIFs) were isolated and analyzed from fresh paired adjacent tissues and HCC for detecting the PUFAs alterations in the HCC TME. Integrated analyses were performed in multiple public databases and local cohorts. Fatty acid desaturase 1 (FADS1) knockdown (KD) HCC cell line was generated to observe the tumor biology and metabolic function. The effects of FADS1 knockout (KO) or overexpression were investigated in multiple spontaneous HCC mouse models via hydrodynamic tail vein injection (HTVI) in vivo. Mutation landscape analysis was used to explore the mechanism of FADS1 transcription. Therapeutic interventions by downregulating FADS1 were also evaluated in vivo. Results: Clinically, we found that the arachidonic acid (ARA) level was enriched in HCC TIFs. A rate-limiting enzyme controlling PUFA biosynthesis, especially ARA production from dihomo-γ-linolenic acid (DGLA), FADS1, was overexpressed in HCC patients. High expression of FADS1 predicted poor survival and was negatively correlated with CD8+CD103+Trm infiltration. Moreover, in the local clinical trial, we noticed that the expression of FADS1 was upregulated in non-response patients with anti-PD-1 mAb treatment. Functionally, we demonstrated that the ARA level was decreased in the conditioned medium (CM) from FADS1 KD cells. Applying CM prolonged the survival of CD8+CD103+Trm ex vivo. FADS1 KO inhibited tumor development by increasing intratumor infiltration and function of CD8+CD103+Trm. In contrast, overexpression of FADS1 promoted HCC progression by restraining immune surveillance in vivo. Mechanistically, we found that the expression of FADS1 was upregulated in the TP53 mutation group by analyzing the mutation landscape of HCC. Mutant P53 protein could bind to the promoter region of FADS1. Therapeutically, recombinant adeno-associated 8 (rAAV8)-shRNAs delivery and anti-PD-1 mAb administration inhibited the tumor growth of anti-PD-1 mAb treatment-resistant HCC model driven by CTNNB1N90 and MYC. Conclusions: We demonstrated that mutant P53 protein directly promoted FADS1 transcription, increasing ARA accumulation in HCC TME. FADS1 remodeling the metabolic patterns of PUFAs impaired CD8+CD103+Trm anti-tumor immunity, possibly leading to HCC progression. Citation Format: Tao Ding, Li Pang, Runying Long, Shinuan Zeng, Kevin TP Ng, Qingmei Zhang, Zhiwei Chen, Kwan Man. Aberrant polyunsaturated fatty acids desaturation impairs survival and anti-tumor immunity of tumor resident memory CD8+ T cell in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1250.

Combination of bicarbonate and low temperature stress induces the biosynthesis of both arachidonic and docosahexaenoic acids in alkaliphilic microalgae Dunaliella salina HTBS

High bicarbonate levels and low temperature may have an impact on microalgae cultivation. However, changes in cellular composition in response to the combination of the above stresses are still poorly understood. In this study, the combined effects of bicarbonate and low temperature on biochemical changes in alkaliphilic microalgae Dunaliella salina HTBS were investigated. Comparing to the control condition of 25°C without bicarbonate, the cell density was increased from 0.69 to 1.18 in the treatment condition of 0.15 M bicarbonate and low temperature (16 °C) while the lipid\protein\carbohydrate contents were increased from 34.71% to 43.94%, 22.44% to 26.03%, 22.62% to 29.18%, respectively. Meanwhile, the PUFAs, arachidonic acid (AA) and docosahexaenoic acid (DHA) contents reached to 3.52% and 4.73% with the combination of low temperature and bicarbonate, respectively, whereas they were not detected when the cells were treated with single condition. Moreover, both the chlorophyll and carotenoid contents were also detected with increased profiles in the combined treatments. As a result, the maximum photochemical efficiency but not reduced non-photochemical quenching was strengthened, which enhanced the photosynthetic performance. Additionally, our results indicated that D. salina HTBS could acclimate to the combined stress by up-regulating the activity of SOD\CAT and reducing MDA content. These findings demonstrated that the addition of a certain bicarbonate under low temperature could effectively enhance the biomass production and accumulation of AA and DHA, which would benefit the development of the microalgae industry in value-added products.

Comparative Genomics of Mortierellaceae Provides Insights into Lipid Metabolism: Two Novel Types of Fatty Acid Synthase.

Fungal species in the family Mortierellaceae are important for their remarkable capability to synthesize large amounts of polyunsaturated fatty acids, especially arachidonic acid (ARA). Although many genomes have been published, the quality of these data is not satisfactory, resulting in an incomplete understanding of the lipid pathway in Mortierellaceae. We provide herein two novel and high-quality genomes with 55.32% of syntenic gene pairs for Mortierella alpina CGMCC 20262 and M. schmuckeri CGMCC 20261, spanning 28 scaffolds of 40.22 Mb and 25 scaffolds of 49.24 Mb, respectively. The relative smaller genome for the former is due to fewer protein-coding gene models (11,761 vs. 13,051). The former yields 45.57% of ARA in total fatty acids, while the latter 6.95%. The accumulation of ARA is speculated to be associated with delta-5 desaturase (Delta5) and elongation of very long chain fatty acids protein 3 (ELOVL3). A further genomic comparison of 19 strains in 10 species in three genera in the Mortierellaceae reveals three types of fatty acid synthase (FAS), two of which are new to science. The most common type I exists in 16 strains of eight species of three genera, and was discovered previously and consists of a single unit with eight active sites. The newly revealed type II exists only in M. antarctica KOD 1030 where the unit is separated into two subunits α and β comprised of three and five active sites, respectively. Another newly revealed type III exists in M. alpina AD071 and Dissophora globulifera REB-010B, similar to type II but different in having one more acyl carrier protein domain in the α subunit. This study provides novel insights into the enzymes related to the lipid metabolism, especially the ARA-related Delta5, ELOVL3, and FAS, laying a foundation for genetic engineering of Mortierellaceae to modulate yield in polyunsaturated fatty acids.

Relevance of ω-6 GLA Added to ω-3 PUFAs Supplements for ADHD: A Narrative Review.

The use of polyunsaturated fatty acids in Attention-Deficit/Hyperactivity Disorder (ADHD) and developmental disorders has been gaining interest with preparations containing different dosages and combinations. Gamma-linolenic acid (GLA) is an ω-6 fatty acid of emerging interest with potential roles as an adjuvant anti-inflammatory agent that could be used with ω-3 PUFAs in the treatment of ADHD and associated symptoms. A narrative review was undertaken to examine the potential role(s) of the ω-6 fatty acid GLA. PubMed, Google Scholar, and Scopus were searched to examine the potential role(s) of the ω-6 fatty acid GLA as (1) an antioxidant and anti-inflammatory agent, (2) a synergistic nutrient when combined with ω-3 PUFAs, and (3) a potential etiological factor in ADHD and its treatment. The results show that GLA exerts anti-inflammatory effects by increasing dihomo-gamma-linolenic acid in immune cells. ω-3 PUFAs, such as EPA and DHA, are often co-administered with GLA because these ω-3 PUFAs may prevent the accumulation of serum arachidonic acid in response to GLA administration without limiting the storage of DGLA in immune cells. The administration of ω-3 PUFAs alone might not be sufficient to effectively treat patients with ADHD and developmental disorders. Overall studies point towards a combination of EPA and DHA with GLA in a 9:3:1 ratio appearing to be associated with ADHD symptom improvement. A combination of PUFAs may lead to better outcomes.

Arachidonic acid, a clinically adverse mediator in the ovarian cancer microenvironment, impairs JAK‐STAT signaling in macrophages by perturbing lipid raft structures

Survival of ovarian carcinoma is associated with the abundance of immunosuppressed CD163highCD206high tumor‐associated macrophages (TAMs) and high levels of arachidonic acid (AA) in the tumor microenvironment. Here, we show that both associations are functionally linked. Transcriptional profiling revealed that high CD163 and CD206/MRC1 expression in TAMs is strongly associated with an inhibition of cytokine‐triggered signaling, mirrored by an impaired transcriptional response to interferons and IL‐6 in monocyte‐derived macrophages by AA. This inhibition of pro‐inflammatory signaling is caused by dysfunctions of the cognate receptors, indicated by the inhibition of JAK1, JAK2, STAT1, and STAT3 phosphorylation, and by the displacement of the interferon receptor IFNAR1, STAT1 and other immune‐regulatory proteins from lipid rafts. AA exposure led to a dramatic accumulation of free AA in lipid rafts, which appears to be mechanistically crucial, as the inhibition of its incorporation into phospholipids did not affect the AA‐mediated interference with STAT1 phosphorylation. Inhibition of interferon‐triggered STAT1 phosphorylation by AA was reversed by water‐soluble cholesterol, known to prevent the perturbation of lipid raft structure by AA. These findings suggest that the pharmacologic restoration of lipid raft functions in TAMs may contribute to the development new therapeutic approaches.

Accumulation of Arachidonic Acid, Precursor of Pro-Inflammatory Eicosanoids, in Adipose Tissue of Obese Women: Association with Breast Cancer Aggressiveness Indicators.

While obesity is linked to cancer risk, no studies have explored the consequences of body mass index (BMI) on fatty acid profiles in breast adipose tissue and on breast tumor aggressiveness indicators. Because of this, 261 breast adipose tissue samples of women with invasive breast carcinoma were analyzed. Fatty acid profile was established by gas chromatography. For normal-weight women, major changes in fatty acid profile occurs after menopause, with the enrichment of long-chain polyunsaturated fatty acids (LC-PUFAs) of both n-6 and n-3 series enrichment, but a stable LC-PUFAs n-6/n-3 ratio across age. BMI impact was analyzed by age subgroups to overcome the age effect. BMI increase is associated with LC-PUFAs n-6 accumulation, including arachidonic acid. Positive correlations between BMI and several LC-PUFAs n-6 were observed, as well as a strong imbalance in the LC-PUFAs n-6/n-3 ratio. Regarding cancer, axillary lymph nodes (p = 0.02) and inflammatory breast cancer (p = 0.08) are more frequently involved in obese women. Increased BMI induces an LC-PUFAs n-6 accumulation, including arachidonic acid, in adipose tissue. This may participate in the development of low-grade inflammation in obese women and breast tumor progression. These results suggest the value of lifestyle and LC-PUFAs n-3 potential, in the context of obesity and breast cancer secondary/tertiary prevention.

Heterotrophic properties of Myrmecia incisa and strategies for enhanced arachidonic acid production

Myrmecia incisa is a valuable microalga worth investigating as it is rich in arachidonic acid (ArA), a polyunsaturated fatty acid that is essential for human health. The present study developed a two-stage cultural strategy for M. incisa. In stage Ⅰ, heterotrophic mode was conducted for the purpose of high algal biomass production. By determining the optimal cultural parameters including dissolved oxygen level, inoculum size, glucose concentration and pH values, the biomass of M. incisa was up to 10.86 g L−1, representing the highest report on the heterotrophic growth of M. incisa so far. In stage Ⅱ, the algae were transferred to phototrophic mode and subjected to nutrient deficiency for the purpose of rapid ArA accumulation. As a result, the final ArA content was 11.95% of dry cell weight with the maximum productivity being 48.52 mg L−1d−1. In addition, it was found that 85.12% of ArA was stored in neutral lipids, which is beneficial for the downstream separation and extraction. Findings of the present study strongly demonstrated the superiority of M. incisa as a promising feedstock for ArA-rich oil.

An increase of phosphatidylcholines in follicular fluid implies attenuation of embryo quality on day 3 post-fertilization

BackgroundAlthough oocyte quality is the dominant factor determining embryo quality, few studies have been conducted to evaluate embryo quality based on the metabolites related to the oocyte. With quantification of the follicular fluid (FF) metabolites, in assisted reproductive technology (ART), this study sought to evaluate the embryo or oocyte quality through an informative approach.ResultsAn evaluation model consisting of 17 features was generated to distinguish the embryo quality on day 3 post-fertilization, and phosphatidylcholines (PCs) were the key contributors to the evaluation. The model was extended to the patients under different ages and hyperstimulations, and the features were further enriched to facilitate the evaluation of the embryo quality. The metabolites were clustered through pathway analysis, leading to a hypothesis that accumulation of arachidonic acid induced by PCs might weaken embryo quality on day 3 post-fertilization.ConclusionsA discriminating model with metabolic features elicited from follicular fluid was established, which enabled the evaluation of the embryo or oocyte quality even under certain clinical conditions, and the increase of PCs in follicular fluid implies the attenuation of embryo quality on day 3 post-fertilization.

Nitric oxide synthesis stimulated by arachidonic acid accumulation via PPARα in acetylcholine-stimulated gastric mucous cells.

What is the central question of this study? Arachidonic acid (AA) stimulates NO production in antral mucous cells without any increase in [Ca2+ ]i . Given that the intracellular AA concentration is too low to measure, the relationship between AA accumulation and NO production remains uncertain. Is AA accumulation a key step for NO production? What is the main finding and its importance? We demonstrated that AA accumulation is a key step for NO production. The amount of AA released could be measured using fluorescence-HPLC. The intracellular AA concentration was maintained at <1μM. Nitric oxide is produced by AA accumulation in antral mucous cells, not as a direct effect of [Ca2+ ]i . In the present study, we demonstrate that NO production is stimulated by an accumulation of arachidonic acid (AA) mediated via peroxisome proliferation-activated receptorα (PPARα) and that the NO produced enhances Ca2+ -regulated exocytosis in ACh-stimulated antral mucous cells. The amount of AA released from the antral mucosa, measured by fluorescence high-performance liquid chromatography (F-HPLC), was increased by addition of ionomycin (10 μM) or ACh, suggesting that AA accumulation is stimulated by an increase in [Ca2+ ]i . The AA production was inhibited by an inhibitor of cytosolic phospholipaseA2 (cPLA2-inhα). GW6471 (a PPARα inhibitor) and cPLA2-inhα inhibited NO synthesis stimulated by ACh. Moreover, indomethacin, an inhibitor of cyclooxygenase, stimulated AA accumulation and NO production. However, acetylsalicylic acid did not stimulate AA production and NO synthesis. An analogue of AA (AACOCF3) alone stimulated NO synthesis, which was inhibited by GW6471. In antral mucous cells, indomethacin enhanced Ca2+ -regulated exocytosis by increasing NO via PPARα, and the enhancement was abolished by GW6471 and cPLA2-inhα. Thus, AA produced via PLA2 activation is the key step for NO synthesis in ACh-stimulated antral mucous cells and plays important roles in maintaining antral mucous secretion, especially in Ca2+ -regulated exocytosis.

Molecular mechanism of arachidonic acid biosynthesis in Porphyridium purpureum promoted by nitrogen limitation.

The red alga Porphyridium purpureum has been known to produce polyunsaturated fatty acids, especially arachidonic acid (ARA), under stressful conditions. However, there is no consistent conclusion about the response of ARA in this alga to nitrogen (N) stress. Also, no research has been done to clearly elucidate the underlying molecular mechanisms of N stress. In this work, P. purpureum CoE1 was cultivated under nitrogen limitation conditions and the putative Δ5-desaturase related gene FADSD5 was isolated. The results showed that the fatty acids in P. purpureum CoE1 were significantly higher in the N limited cultures (54.3mgg-1) than in the N-replete cultures (45.3mgg-1) at the 18th day (t-test, p < 0.001), which was attributed to the upregulated abundance of the putative Δ5-desaturase related protein, Δ5-Des. The study also indicated that the expression of the putative Δ5-desaturase related gene, FADSD5, increased with cell growth, demonstrating considerable potentials for ARA biosynthesis in P. purpureum CoE1. These results might guide the direction in illuminating the biosynthetic pathway of fatty acids with molecular evidence and enable genetic modifications of P. purpureum CoE1 for enhancing the ARA accumulation.

An Increase of Phosphatidylcholines in Follicular Fluid Implies Attenuation of Embryo Quality

Background: Although oocyte quality is the dominant factor determining embryo development, while the metabolites related with oocyte are sensitive to reflect the alive oocyte, there is few study to take the metabolites in follicular fluid (FF), a microenvironment of oocyte living, for evaluation of embryo quality. Methods: The FFs were donated from the patients who received in vitro fertilization-embryo transfer or intracytoplasmic sperm injection. The embryo quality was preliminarily judged by the development status of embryo on day 3 under microscope. The extracted metabolomes in the FFs were quantitated with triple quadrupole mass spectrometer. Based on the metabolomic datasets, the statistical tools such as Wilcoxon rank-sum tests, principle component analysis and random forest were employed under unsupervised or supervised condition to seek a discrimination panel for good or poor embryo. Weighted gene co-expression network analysis was taken to find out the pathway linkages among the panel metabolites. Findings: An evaluation model consisting of 17 features was generated to distinguish the embryo quality and phosphatidylcholines were the key contributors for the evaluation. The model was extended to the patients under different age and hyperstimulations and the features were further enriched to facilitate the evaluation of embryo quality. The metabolites were clustered through pathway analysis, leading a hypothesis that accumulation of arachidonic acid induced by phosphatidylcholines might weaken embryo quality. Interpretation: As the metabolomics in FF reflects the metabolite exchanges between oocyte and its microenvironment, the corresponding changes in FF are likely to setup a new assessment to oocyte or embryo. Funding Statement: This work was supported by the National Key Research and Development Program of China (2017YFC0906703, 2016YFC1000200 and 2018YFC1003100), the National Natural Science Foundation of China (81873478), the Science and Technology Major Project of the Ministry of Science and Technology of Hunan Province, China (2017SK1030), and Hunan Provincial Grant for Innovative Province Construction (2019SK4012). Declaration of Interests: Authors declare no competing interests. Ethics Approval Statement: This study was approved by the Ethics Committee of the Reproductive and Genetic Hospital of CITIC-XIANGYA (reference LLSC-2018-036) and Beijing Genomics Institute (BGI) (reference BGI-IRG 20035).

Reproductive performance in virgin pikeperch (Sander lucioperca L.) females fed different dietary levels of arachidonic acid with respect to the duration of spawning induction

Pikeperch (Sander lucioperca) is a species of significant importance for the further development of intensive aquaculture, what makes the total control over species’ reproductive cycle a high priority task. The present study aimed to assess the effect of arachidonic acid (AA) dietary enrichment on the reproductive performance in virgin females (two-years-old; individual weight 1.0 ± 0.2 kg) kept in fully controlled conditions with respect to different time of hormonal application. Two groups of breeders, ARA (fed AA enriched diet) and CTRL (fed control feed), were reared in two separated tanks of the recirculation system over the course of seven months. Five, six, and seven months after the start of trial, batches of five pairs of breeders (in total 15 pairs per each feeding group) from each group were hormonally treated. Ovulations occurred after six and seven months (oocyte diameter range 912−1030 μm), and samples of dry eggs were taken for the analysis of fatty acid profiles. Among the parameters of reproductive success, the embryo survival was significantly affected by the diet, while induction duration affected latency time only. The CTRL group females showed overall higher embryo survival across both reproduction occasions (p = 0.028) than group fed AA enriched diet (35.7 ± 17.1 % and 18.6 ± 13.6 % in CTRL and ARA group, respectively). A significant accumulation of AA was found in ARA group eggs in both reproduction batches. Virgin pikeperch breeders appear to keep at least one month plasticity towards the duration of spawning induction in controlled conditions and optimal oocyte diameter range for artificial reproduction is between 900−1000 μm. Levelling dietary AA with eicosapentaenoic acid during the entire photothermal protocol negatively altered the egg quality.

Evaluation and Transcriptome Analysis of the Novel Oleaginous Microalga Lobosphaera bisecta (Trebouxiophyceae, Chlorophyta) for Arachidonic Acid Production.

Arachidonic acid (AA) is an omega-6 long-chain polyunsaturated fatty acid and is important for human health. The coccoid green microalga Lobosphaera bisecta has been reported to be able to accumulate high AA content under certain conditions. Nutrient management and light intensity had significant effects on the biomass and accumulation of lipids and AA in L. bisecta SAG2043. Both a high nitrogen concentration (18 mM) and high light intensity (bilateral light-300 μmol m−2 s−1) were beneficial to the growth of L. bisecta, and the replacement of culture medium further enhanced the biomass, which reached 8.9 g L−1. Low nitrogen concentration (3.6 mM) and high light significantly promoted the accumulation of lipids and AA. The highest lipid and AA content reached 54.0% and 10.8% of dry weight, respectively. Lipid compositions analysis showed that 88.2% of AA was distributed within the neutral lipids. We then reconstructed the lipid metabolic pathways of L. bisecta for the first time, and demonstrated that the upregulation of a key desaturase and elongase in the Δ6 pathway was conducive to the accumulation of fatty acids toward AA synthesis. L. bisecta SAG2043 exhibits high biomass, lipid and AA production. It may be a potential candidate for AA production.

A More Comprehensive Approach to the Neuroprotective Potential of Long-Chain Polyunsaturated Fatty Acids in Preterm Infants Is Needed-Should We Consider Maternal Diet and the n-6:n-3 Fatty Acid Ratio?

There is growing evidence that long-chain polyunsaturated fatty acids (LCPUFAs) are of importance for normal brain development. Adequate supply of LCPUFAs may be particularly important for preterm infants, because the third trimester is an important period of brain growth and accumulation of arachidonic acid (n-6 LCPUFA) and docosahexaenoic acid (n-3 LCPUFA). Fatty acids from the n-6 and n-3 series, particularly, have important functions in the brain as well as in the immune system, and their absolute and relative intakes may alter both the risk of impaired neurodevelopment and response to injury. This narrative review focuses on the potential importance of the n-6:n-3 fatty acid ratio in preterm brain development. Randomized trials of post-natal LCPUFA supplementation in preterm infants are presented. Pre-clinical evidence, results from observational studies in preterm infants as well as studies in term infants and evidence related to maternal diet during pregnancy, focusing on the n-6:n-3 fatty acid ratio, are also summarized. Two randomized trials in preterm infants have compared different ratios of arachidonic acid and docosahexaenoic acid intakes. Most of the other studies in preterm infants have compared formula supplemented with arachidonic acid and docosahexaenoic acid to un-supplemented formula. No trial has had a comprehensive approach to differences in total intake of both n-6 and n-3 fatty acids during a longer period of neurodevelopment. The results from preclinical and clinical studies indicate that intake of LCPUFAs during pregnancy and post-natal development is of importance for neurodevelopment and neuroprotection in preterm infants, but the interplay between fatty acids and their metabolites is complex. The best clinical approach to LCPUFA supplementation and n-6 to n-3 fatty acid ratio is still far from evident, and requires in-depth future studies that investigate specific fatty acid supplementation in the context of other fatty acids in the diet.

The Omega-3 Fatty Acids EPA and DHA, as a Part of a Murine High-Fat Diet, Reduced Lipid Accumulation in Brown and White Adipose Tissues.

Excess energy intake can trigger an uncontrolled inflammatory response, leading to systemic low-grade inflammation and metabolic disturbances that are hypothesised to contribute to cardiovascular disease and type 2 diabetes. The long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are suggested to mitigate this inflammatory response, but the mechanisms are unclear, especially at the tissue level. Adipose tissues, the first tissues to give an inflammatory response, may be an important target site of action for EPA and DHA. To evaluate the effects of EPA and DHA in white and brown adipose tissues, we fed male C57Bl/6J mice either a high fat diet (HFD) with 5% corn oil, an HFD with 40% of the corn oil substituted for purified EPA and DHA triglycerides (HFD-ED), or normal chow, for 8 weeks. Fatty acid profiling and transcriptomics were used to study how EPA and DHA affect retroperitoneal white and brown adipose tissues. HFD-ED fed mice showed reduced lipid accumulation and levels of the pro-inflammatory fatty acid arachidonic acid in both white and brown adipose tissues, compared with HFD-corn oil fed animals. The transcriptomic analysis showed changes in β-oxidation pathways, supporting the decreased lipid accumulation in the HFD-ED fed mice. Therefore, our data suggests that EPA and DHA supplementation of a high fat diet may be anti-inflammatory, as well as reduce lipid accumulation in adipose tissues.

Alteration of erythrocyte membrane polyunsaturated fatty acids in preterm newborns with retinopathy of prematurity

Extremely preterm infants are at high risk for retinopathy of prematurity (ROP), a potentially blinding disease characterized by abnormalities in retinal vascularization. Whereas animal studies revealed that n-3 polyunsaturated fatty acids (PUFAs) may be of benefit in preventing ROP, human studies conducted on preterm infants during the 1st weeks of life showed no association between blood n-3 PUFA bioavailability and ROP incidence and/or severity, probably because of the influence of nutrition on the lipid status of infants. In the OmegaROP prospective cohort study, we characterized the erythrocyte concentrations of PUFAs in preterm infants aged less than 29 weeks gestational age (GA) without any nutritional influence. We show that GA is positively associated with the erythrocyte n-6 to n-3 PUFA ratio, and particularly with the ratio of arachidonic acid (AA) to docosahexaenoic acid (DHA), in infants with ROP. A time-dependent accumulation of AA at the expense of DHA seems to occur in utero in erythrocytes of preterm infants who will develop ROP, thus reinforcing previous data on the beneficial properties of DHA on this disease. In addition, preliminary data on maternal erythrocyte membrane lipid concentrations suggest modifications in placental transfer of fatty acids. Documenting the erythrocyte AA to DHA ratio at birth in larger cohorts might be useful to set up new prognostic factors for ROP.

Alox15b Gene Contributes to Lymphoma Tumorigenesis Via PI3K/AKT/mTOR Pathway Activation and Has a Synergistic Effect with Alox5 Gene

Deletion of the short arm of chromosome 17(del17p) is associated with resistance to standard treatment and the very poor clinical outcome in lymphocytic malignancy. Alongside with TP53 gene, ALOX15B gene is also lost in del(17p) patients. In our pervious study, partially knockdown of Alox15b in mice could accelerate lymphoma tumorigenesis with or without TP53 loss. Accumulation of arachidonic acid (AA) and reduction of apoptosis was observed. But how Alox15b gene and AA effect lymphoma tumorigenesis is not fully understood. Here we show that PI3K/AKT/mTOR pathway is activated in Alox15b-knockdown lymphocytes and contributes to the drug resistance. Besides, we also find that Alox15bgene and Alox5gene play a synergistic role lymphoma tumorigenesis in mice model.Experiments were performed using murine preB cell line, baf3 cell. We introduced shRNAs targeting Alox15b at 2 different loci (shAlox15b.1252 and shAlox15b.2865) to create 2 separated Alox15b-deficient cell lines. Intracellular AA level was tested by liquid chromatograph-mass spectrometer(LC-MS). And Alox15b-deficient lymphocytes showed an accumulation of intracellular AA.Then the activation status of PI3K/AKT/mTOR pathway was detected by examining the phosohor-S6 (pS6) protein level using Western Blot assay in wild-type baf3 cells with exogenous-added AA and Alox15b-deficient baf3 cell lines respectively. The results showed that exogenous-added AA activated PI3K/AKT/mTOR pathway in a dose-dependent manner in wild-type baf3 cells. Also, Alox15b-dificient baf3 cell lines showed an increase in pS6 protein level than control, suggesting that in Alox15b-deficient lymphocytes, PI3K/AKT/mTOR pathways is activated via accumulation of AAIn addition, the cell viability test was involved to test how Alox15b gene knockdown affected lymphocyte's reaction to rapamycin(RAPA), a mTOR inhibitor. The results showed Alox15b-dificient baf3 cells are more resistant to RAPA, which indicated that mTOR inhibitors may not be a suitable choice in del17p patients.At Last, we collected primary murine lymphoma cells induced by shAlox15b-shTP53/shREN-shTP53 and blood sample from del17p/non-del17p CLL patients to verify our assumption. In mice samples, as AA accumulation was already observed in previous study, we only test pS6 level. And one sample from each experimental group (shAlox15b-shTP53) showed an increase in pS6 level. In human samples, we can see a slightly increase in AA in del17p patient. But due to individual variation, the result isn't statistical significant.Besides, we constructed a plasmid, namely eMLM-shAlox15b-shAlox5, with 2 shRNA targeting Alox5 and Alox15b gene at the same time, introduced the plasmid into primary murine preB cells and transplanted back to recipient mice. After verified by flow cytometry and pathological staining, survival analysis revealed the fact that silencing Alox5 and Alox15b gene at the same time can accelerate lymphoma formation, suggesting that Alox5 and Alox15b gene have a synergistic effect in lymphoma tumorigenesis. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.