Higher Dietary Arachidonic Acid Levels Improved the Growth Performance, Gonad Development, Nutritional Value, and Antioxidant Enzyme Activities of Adult Sea Urchin(Strongylocentrotus intermedius)

The gonads of sea urchins(Strongylocentrotus intermedius) are characterized by high levels of arachidonic acid(ARA, 20:4 n-6) and eicosapentaenoic acid(EPA, 20:5 n-3). However, to our knowledge, little information is available regarding the physiological response of adult sea urchins to dietary ARA. In the present study, four dietary feeds were formulated with graded ARA(0, 0.5%, 1%, and 2% dry diet). Each diet was randomly allocated to three cages during a 56-day feeding experiment. The results showed that the sea urchin weight gain rate(WGR) and the gonadosomatic index(GI) significantly increased as ARA was equal to or above 1.0% of dry diet(P < 0.05). The activities of superoxide dismutase(SOD), catalase(CAT), and total anti-oxidative capacity(T-AOC) were the highest in the coelomic fluid of sea urchins that were fed diets with 1% ARA. The total essential amino acid(TEAA) and its ratio to total non-essential amino acid(TNEAA) showed a similar tendency to WGR and GI as dietary ARA increased, and the highest TEAA and TEAA/TNEAA were observed in the gonads of sea urchins that were fed diets with 1% ARA. Levels of ARA and ARA/EPA of the gonads increased while n-3/n-6 polyunsaturated fatty acid(PUFA) decreased with the increase of dietary ARA(P < 0.05). EPA in the gonads of experimental animals fed with formulated feeds showed no significant differences(P> 0.05), but was significantly lower than those fed with kelp(P < 0.05). These results suggested that relatively higher levels of ARA(1% dry diet) significantly promoted growth, gonad development, activities of antioxidant enzymes, as well as nutritional values(TEAA, TEAA/TNEAA, and PUFA) of adult S. intermedius.

Hepatitis B virus X protein promotes liver cell proliferation via a positive cascade loop involving arachidonic acid metabolism and p-ERK1/2

Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upregulated the levels of cyclooxygenase-2 （COX-2）, 5-1ipoxygenase （5-LOX） and phosphorylated extracellular signal-regulated protein kinases 1/2 （p-ERK1/2） in liver cells. HBx-induced p-ERK1/2 was abolished by inhibition of Gi/o proteins, COX or LOX. In addition, HBx increased the amounts of prostaglandin E2 （PGE2） and leukotriene B4 （LTB4） released from cell lines derived from hepatocytes. Moreover, these released arachidonic acid metabolites were able to activate ERK1/2. Interestingly, activated ERK1/2 could upregulate the expression of COX-2 and 5-LOX in a positive feedback manner. In conclusion, HBx enhances and maintains liver cell proliferation via a positive feedback loop involving COX-2, 5-LOX, released arachidonic acid metabolites, Gi/o proteins and p-ERK1/2.

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA (TREBOUXIOPHYCEAE,CHLOROPHYTA) EXPOSED TO HIGH PFD

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve of Parietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobioreactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m 2·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%-41%) followed by linoleic acid (17%-21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m 2·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate.

PHYSIOLOGICAL INHIBITORY EFFECT OF OCS IN ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA (TREBOUXIOPHYCEAE, CHLOROPHYTA)

Parietochloris incisa is an arachidonic acid rich snow green alga. The main physiological profiles, such as ash free dry weight (AFDW), chlorophyll, carotenoid, protein and total fatty acids (TFA), in this alga exposed to old culture supernatant (OCS) at the decline phase or its crude ethyl acetate extracts (CEAE) were investigated by using tubular photobioreactors of different diameters. Results showed that both OCS and CEAE had strong inhibitory effect on the above physiological parameters. The longer the culture was exposed to OCS and the more CEAE were added into the algal culture, the more the above physiological properties were inhibited. Arachidonic acid (AA), the dominant component of fatty acids in this alga, was also seriously inhibited with respect to total TFA, AFDW of cell mass, or culture volume, due to a probable reduction of enzymes activities catalyzing chain elongation from C18:1ω9 to AA. These results incontestably evidenced that some CEAE dissolving substances existing in OCS, like auto inhibitors, inhibited P. incisa growth through feedback. Hence, any efficient removal of auto inhibitors from algal culture to decrease their bioactivity could be good for maximal production of desired products like AA.

A Research Overview on Arachidonic Acid:Fermentation Regulation and Purification

Arachidonic acid （ARA or AA）, one of the most important polyunsaturated fatty acids （PUFAs）, has various physiological activities and positive effects on human health. ARA production by Mortierella alpina has become a hot topic in recent years, owing to that it is effective, safe and easy to control. How to improve ARA yield and purification efficiency is important to ARA production in M. alpina. Therefore, in this review, we summarized some methods to improve ARA yield： optimization of culture conditions, mycelium aging technologies and metabolic regulation, and the commonly used methods for ARA isolation and purification, to provide a theoretical basis for ARA production by M. alpina fermentation.

Enhancement of Arachidonic Acid Production by Mortierella isabellina Through Protoplast Regeneration Mutagenesis

A developed method was used for the enhancement of arachidonic acid production by M. isabellina. An orthogonal, rotatable and central composite design was applied to determine the optimum conditions for protoplast regeneration mutagenesis. The results showed that a commixture enzyme （cellulase and glusulase） at the concentration of 4%, enzymolysis temperature at 30℃ and enzymolysis time on 7.5 h were the optimal conditions, in which the lethality of M. isabellina spores was 78.4%. After mutagenesis and re-screenings, M. isabellina mutant Y-69 was obtained. GC analysis showed that the yield of arachidonic acid by Y-69 （2.92 g. L-1） was 3.56 times higher than that of the wild-type strain （0.82 g.L-1）. Pass generation tests showed that the properties of Y-69 by mutation were readily inherited.

Functional characterization of a Δ6 fatty acid desaturase gene and its 5′-upstream region cloned from the arachidonic acid-rich microalga Myrmecia incisa Reisigl(Chlorophyta)

It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors.

Long-term modifications of blood pressure in normotensive and spontane-ously hypertensive rats by gene delivery of rAAV-mediated cytochrome P450 arachidonic acid hydroxylase

Arachidonic acid cytochrome P-450 （CYP） hydroxylase 4A isoforms, including 4A1, 4A2, 4A3 and 4A8 in the rat kidney, catalyze arachidonic acid to produce 19/20-Hydroxyeicosatetraenoic acids （20-HETE）, a biologically active metabolite, which plays an important role in the regulation of blood pressure. However, controversial results have been reported regarding the exact role of 20-HETE on blood pressure. In the present study, we used recombinant adenoassociated viral vector （rAAV） to deliver CYP 4A1 cDNA and antisense 4A1 cDNA into Sprague-Dawley （SD） rats and spontaneously hypertensive rats （SHR）, respectively, to investigate the effects of long-term modifications of blood pressure and the potential for gene therapy of hyperténsion. The mean systolic pressure increased by 14.2±2.5 mm Hg in rAAV.4A 1-treated SD rats and decreased by 13.7±2.2 mm Hg in rAAV.anti4A l-treated SHR rats 5 weeks after the injection compared with controls and these changes in blood pressure were maintained until the experiments ended at 24 weeks. In 4A1 treated animals CYP4A was overexpressed in various tissues, but preferentially in the kidney at both mRNA and protein levels. In anti-4Al-treated SHR, CYP4A mRNA in various tissues was probed, especially in kidneys, but 4A l protein expression was almost completely inhibited. These results suggest that arachidonic acid CYP hydroxylases contribute not only to the maintenance of normal blood pressure but also to the development of hypertension. rAAV-mediated anti4A administration strategy has the potential to be used as targeted gene therapy in human hypertension by blocking expression of CYP 4A in kidneys.

Docosahexaenoic acid suppresses arachidonic acid-induced proliferation of LS-174T human colon carcinoma cells

AIM： To investigate the impact of arachidonic acid （AA） and docosahexaenoic acid （DHA） and their combination on colon cancer cell growth. METHODS： The LS-174T colon cancer cell line was used to study the role of the prostaglandin precursor AA and the omega-3 polyunsaturated fatty acid DHA on cell growth. Cell viability was assessed in XTT assays. For analysis of cell cycle and cell death, flow cytometry and DAPI staining were applied. Expression of cyclooxygenase-2 （COX-2）, p21 and bcl-2 in ceils incubated with AA or DHA was examined by real-time RT-PCR. Prostaglandin E2 （PGE2） generation in the presence of AA and DHA was measured using a PGE2- ELISA. RESULTS： AA increased cell growth, whereas DHA reduced viability of LS 174T cells in a time- and dosedependent manner. Furthermore, DHA down- regulated mRNA of bcl-2 and up-regulated p21. Interestingly, DHA was able to suppress AA-induced cell proliferation and significantly lowered AA-derived PGE2 formation. DHA also down-regulated COX-2 expression. In addition to the effect on PGE2 formation, DHA directly reduced PGE2-induced cell proliferation in a dosedependent manner. CONCLUSION： These results suggest that DHA can inhibit the pro-proliferative effect of abundant AA or PGE2.

Evaluation of the inhibitory effect of docosahexaenoic acid and arachidonic acid on the initial stage of amyloid β1-42 polymerization by fluorescence correlation spectroscopy

Amyloid β(Aβ)1-42 fibrillation is a crucial step in the development of pathological hallmarks, such as neuritic plaques and neurofibrillary tangles, of Alzheimer’s disease (AD). In this study, we evaluated the effects of free docosahexaenoic acid (DHA), an essential brain polyunsaturated fatty acid (PUFA), on the inhibition of Aβ1-42 fibrillation by fluorescence correlation spectroscopy (FCS), a technique capable of detecting molecular movements and interactions in solution. We also examined whether free arachidonic acid (AA), eicosapentaenoic acid (EPA), and metabolites of DHA, including neuroprotectin D1 (NPD1, 10S, 17S-dihydroxy-DHA), resolvin D1 (RvD1, 7S, 8R, 17S-trihydroxy-DHA), and didocosahexaenoyl glycerol (diDHA), affect Aβ1-42 polymerization. The results of the FCS study reveal that DHA and AA significantly reduced the diffusion time of TAMRA (5-carboxytetramethylrhoda-mine)-Aβ1-42 by 28% and 31%, respectively, while EPA, NPD1, RvD1, and diDHA had no effects on diffusion time. These results indicate that DHA and AA inhibited Aβ1-42 polymerization and that their inhibitory effects occurred at the initial stage of Aβ1-42 polymerization. This study will advance the research on PUFAs in preventing AD progression.

Arachidonic acid Metabolism in Galactosamine／Endotoxin Indudced Acute Liver injury in Rats

The changes of the levels of LTC4, PGI2 and TXA2 in the liver tissue in SD rats with GaIN/LPS-induced acute liver injury was studied with radioimmunoassay (RIA). As a result,12h after the administration of GaIN/LPS, serum AST (398±37u), ALT (565 ±43u) increased (P<0.001 ) and the concentration of TXA2 (12188±588pg/g· w· wt) in liver tissue increased sigiuficantly(p<0.001), while the content of LTC4 (9713± 3557ng/g·w·wt ) and PGI2 (1748±560 pg/g· w·wt) in liver tissue were not obviously changed(p>0.05) and the inflammatory changes of the pathological findings were observed. The improvement of serum ALT (300±168u)(p< 0.05) and AST(273±424 u) (P<0. 05) and histopathological damage was observed after the administration of diethylcarbamazine (DEC), a LTA4 synthesis inhibitor, the liver TXA2(12740±699) concentration significantly increased (P<0. 001), while the levels of LTC4 (8179±1653) and PGI2 (2320±630) were not obviously changed. Serum ALT (536±74u) and AST (416± 41u)(P> 0. 05) levels and histopathology did not change with administration of indomethacin, a cyclooxygenase inhibitor, but the liver LTC4 (12166±13027) contents increased (P<0.05 ) and TXA2 (1868±791) reduced significantly (P<0. 001). The present study suggests that arachidonic acid metabolism in rats with acute liver injury are significantly abnormal. Leukotrienes and thromboxane are important inflammatory mediators in the liver injury.

花生四烯酸(ARA)对凡纳对虾亲本繁殖、免疫及脂质代谢的影响

为探究花生四烯酸(ARA)对凡纳对虾亲本繁殖、免疫及脂质代谢的影响,实验根据实际亲虾培育与幼体生产模式,选取6月龄,大小规格一致的雄虾与单侧眼柄切除的雌虾,随机分为5组,雌雄分开养殖,分别投喂含有不同含量ARA(0.03%、2.70%、4.99%、10.63%)的软颗粒饲料(分别命名为Z1~Z4组)与纯生物饵料(沙蚕)的生产组(Z5)。结果显示,摄食饲料的雌虾增重率(WGR)比生产组显著提升,亲本肝胰腺指数(HSI)随着ARA含量的增加呈现先升后降的整体趋势,在4.99%ARA影响下亲本肝胰腺发育良好,孵化率最高,幼体产量最多质量最好,且卵巢发育相关基因(Vtg、VtgR、VASA与FAMeT2)表达最高;4.99%ARA添加量还可影响雌虾肝胰腺脂质代谢水平,提高脂质利用与转运相关基因(PL、SREPB与FATB)表达,进而影响受精卵中脂肪酸成分变化,显著增加功能性脂肪酸DHA含量,同时影响其中∑n-3 PUFA与∑n-6 PUFA含量及其之间比值。因繁殖与免疫的拮抗关系,造成该ARA含量下抗氧化应激与非特异免疫水平下降。研究表明,饲料中添加不同ARA能够影响凡纳对虾亲本生长与繁殖、免疫及脂质代谢能力,在优先考虑繁殖性能下,建议在亲虾饲料中保持4.99%ARA更能促进卵巢发育与幼体生产。

Mutagenesis of Arachidonic Acid-producing Mortierella Isabellina and Analyses of Δ~6-desaturase Role by qPCR

Arachidonic acid （AA or ARA）, an essential to-6 polyunsaturated fatty acid （PUFA）, can be produced by Mortierella isabellina. Mutagenesis on Mortierella isabellina As3.3410 was induced to raise ARA production. The mutant strain of YZ-124 had the highest ARA of 4.72 g. L-1, which was 5.5 times higher than that of the original strain 3.3410. mRNA expression level of △ 6- desaturase was determined in five different kinds of ARA-producing Mortierella isabellina after cultured for 7 days, and in the mutant strain YZ-124 over a 3-8 day time-course. In addition, the desaturase activity and ARA content were measured at the selected time points. The lowest expression of △6-desaturase was observed in the original strain and the highest expression in the mutant strain YZ-124, which increased with increasing time in culture. Furthermore, a positive correlation was observed between the expression levels of △6-desaturase and ARA content. Based on this, △6-desaturase played a significant role in ARA synthesis pathway in Mortierella isabellina.

Involvement of Oxidative Stress and Down-Regulation of Bcl-2 in Arachidonic Acid-Induced Apoptosis in HUVECs

Human umbilical vein endothelial cells （HU VECs） were treated with arachidonic acid （AA）. After 24 h exposure to AA, typical morphological changes of apoptosis were observed by Giemsa stain and transmission electron microscopy. The apoptotic ratio in HUVECs treated with 50μmol/L, 100μmol/L and 150μmol/L AA were （20.7±3.6）%, （38.6±4.3）% and （52.5±7.5） % respectively. Contrarily, low concentration of AA （425μmol/L） exerted no influence on cell viability by MTT assay. Intracellular malondialdehyde increased significantly in a dose-dependent manner upon AA treatment and for the reduced glutathione. the opposite tendency was found Western Blots show that apoplosis triggered by AA was associated with the down-regulation of Bcl-2 expression, but not with Bax and p53. Pretreatment with 50μmol/L α-tocopherol reduced AA-induced oxidative stress and apoptosis, also inhibited the dowwregulation of Bcl-2/Bax ratio. These results suggested that high concentration of free AA could induce apoptosis in HUVECs probably via oxidative stress and down-regulation of Bcl-2.

Research on Arachidonic Acid and Eicosapentaenoic Acid Anabolic Metabolism in Diasporangium sp.

The fatty acids of a strain of Diasporangium sp.had been analyzed by using GC-MS.The fatty acids of twenty mutants were determined.Based on these results,the producing of eicosapentaenoic acid(EPA)supposed via 18∶2,18∶3,20∶3,20∶4 which all belong to ω-6 fatty acids.The ω-3 desaturation was undertaken at arachidonic acid(AA).In addition,mutant strains resulted in enhanced content of AA which could get two times more than initial strain,but no compact on EPA.

Shuffling the cards in signal transduction: Calcium, arachidonic acid and mechanosensitivity

Cell signaling is a very complex network of biochemical reactions triggered by a huge number of stimuli coming from the external medium. The function of any single signaling component depends not only on its own structure but also on its connections with other biomolecules. During prokaryotic-eukaryotic transition, the rearrangement of cell organization in terms of diffusional compartmentalization exerts a deep change in cell signaling functional potentiality. In this review I briefly introduce an intriguing ancient relationship between pathways involved in cell responses to chemical agonists (growth factors, nutrients, hormones) as well as to mechanical forces (stretch, osmotic changes). Some biomolecules (ion channels and enzymes) act as "hubs", thanks to their ability to be directly or indirectly chemically/mechanically co-regulated. In particular calcium signaling machinery and arachidonic acid metabolism are very ancient networks, already present before eukaryotic appearance. A number of molecular "hubs", including phospholipase A2 and some calcium channels, appear tightly interconnected in a cross regulation leading to the cellular response to chemical and mechanical stimulations.

The Property and Application of Arachidonic Acid

Arachidonic acid (AA) is one of the most important PUFAs (polyunsaturated fatty acids) in human body. A high-yield arachidonic acid-producing strain (mortierella alpina) was selected by ion implantation (the relative content of arachidonic acid is 70.2% among all fatty acids). This paper mainly introduced the structure, distribution, source, physiologic healthcare function and application of AA.

Microwave Irradiated Cross Coupling of Carboxylic Acids and Crotyl Bromides: Efficient Application to Make Arachidonic Acid Esters

A microwave irradiated palladium-catalyzed reaction of carboxylic acids and crotyl type bromides creates series of esters in good to high yields. This facile ester synthesis then is applied to make esters from arachidonic acid, salicylic acid, folic acid, and aspirin efficiently.

Comprehensive analysis reveals an arachidonic acid metabolism-related gene signature in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma(PDAC)is highly heterogeneous,making its prognosis prediction difficult.The arachidonic acid(AA)cascade is involved in carcinogenesis.Therefore,the metabolic enzymes of the AA cascade consist of lipoxygenases(LOXs),phospholipase A2s(PLA2s),and cyclooxygenases(COXs)along with their metabolic products,including leukotrienes.Nevertheless,the prognostic potential of AA metabolism-associated PDAC has not been explored.Herein,the mRNA expression patterns and the matching clinical information of individuals with PDAC were abstracted from online data resources.We employed the LASSO Cox regression model to develop a multigene clinical signature in the TCGA queue.The GEO queue and the ICGC queue were employed as the validation queue.There was differential expression of a significant number of AA metabolism-associated genes(56.8%)between PDAC and neighboring nonmalignant tissues in the TCGA queue.Univariate Cox regression demonstrated that 13 of the differentially expressed genes(DEGs)were linked to overall survival(OS)(p<0.05).A 6-gene clinical signature was developed for stratifying the PDAC patients into two risk groups,with the high-risk group patients exhibiting remarkably lower OS than the low-risk group patients(p<0.001 in the TCGA data set and the ICGC queue,and p=0.001 in the GEO data set).The multivariate Cox data revealed the risk score as an independent OS predictor(HR>1,p<0.01).The receiver operating characteristic(ROC)curve verified the predictive potential of our signature.The expression and alteration of the six genes in PDAC were also validated using online databases.Functional analyses demonstrated that immune-linked cascades were enriched,and the immune status was remarkably different between the high-and low-risk groups.In summary,an AA metabolism-associated clinical gene signature can be applied for prognostic estimation in PDAC.

A role for lipids as agents to alleviate stroke damage： the neuroprotective effect of 2-hydroxy arachidonic acid

Cerebrovascular accident（CVA）or stroke is one of the world＇s leading causes of death and permanent disability.The high social and medical costs associated with this pathology mean there is an urgent need to find effective therapies.Occlusion of the middle cerebral artery（MCAO）,mainly by clots,is the origin of most CVAs in humans.