Temperature effects on lipid properties of microalgae Tetraselmis subcordiformis and Nannochloropsis oculata as biofuel resources

Microalgae Tetraselmis subcordiformis and Nannochloropsis oculata were cultured at 15,20,25,30,and 35℃ and their properties as potential biofuel resources were examined.The results indicate that T.subcordiformis and N.oculata grew best at 20℃ and 25℃ and yielded the highest total lipids at 20℃and 30℃,respectively.With increased temperature,neutral lipid and polyunsaturated fatty acids(FAs)decreased while saturated FAs increased,accompanied by increased monounsaturated FAs(MUFAs) in T.subcordiformis and decreased MUFAs in N.oculata;meanwhile,the predicted cetane number of FA methyl esters increased from 45.3 to 47.6 in T.subcordiformis and from 52.3 to 60.3 in N.oculata.Therefore,optimizing culture temperatures is important for improving microalgal biodiesel production.

Excess dietary cholesterol may have an adverse effect on growth performance of early post-larval Litopenaeus vannamei

One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannameL Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol （D1, D2, D3 and D4 with 0, 0.5%, 1% and 2% cholesterol, respectively） were fed to triplicate groups of L. vannamei shrimp （mean initial wet weight 0.8 mg） for 27 days. After the trial, shrimp fed the D1 diet had the best growth performance （final body weights： FBW; weight gain： WG; specific growth rate： SGR）, while there was no significant difference between diet treatments with respect to survival. The whole body crude protein level in the shrimp decreased with the increase in dietary cholesterol levels, while the whole body crude lipid level in shrimps in the D4 diet treatment was significantly higher （P 〈 0.05） than in other diet treatments. Dietary analysis indicated that the D1 diet contained 0.92% cholesterol prior to supplementation, which may have satisfied the dietary cholesterol requirement of post-larval L. vannamei; excess dietary cholesterol may thus lead to adverse effects on the growth performance of post-larval shrimp.

Dietary arachidonate in milk replacer triggers dual benefits of PGE2 signaling in LPS-challenged piglet alveolar macrophages

Background: Respiratory infections challenge the swine industry, despite common medicinal practices. The dual signaling nature of PGE2(supporting both inflammation and resolution) makes it a potent regulator of immune cell function. Therefore, the use of dietary long chain n-6 PUFA to enhance PGE2 effects merits investigation.Methods: Day-old pigs(n = 60) were allotted to one of three dietary groups for 21 d(n = 20/diet), and received either a control diet(CON, arachidonate = 0.5% of total fatty acids), an arachidonate(ARA)-enriched diet(LC n-6,ARA = 2.2%), or an eicosapentaenoic(EPA)-enriched diet(LC n-3, EPA = 3.0%). Alveolar macrophages and lung parenchymal tissue were collected for fatty acid analysis. Isolated alveolar macrophages were stimulated with LPS in situ for 24 h, and m RNA was isolated to assess markers associated with inflammation and eicosanoid production.Culture media were collected to assess PGE2 secretion. Oxidative burst in macrophages was measured by: 1)oxygen consumption and extracellular acidification(via Seahorse), 2) cytoplasmic oxidation and 3) nitric oxide production following 4, 18, and 24 h of LPS stimulation.Results: Concentration of ARA(% of fatty acids, w/w) in macrophages from pigs fed LC n-6 was 86% higher than CON and 18% lower in pigs fed LC n-3(P < 0.01). Following LPS stimulation, abundance of COX-2 and TNF-α mRNA(P < 0.0001), and PGE2 secretion(P < 0. 01) were higher in LC n-6 PAM vs. CON. However, ALOX5 abundance was1.6-fold lower than CON. Macrophages from CON and LC n-6 groups were 4-fold higher in ALOX12/15 abundance(P < 0.0001) compared to LC n-3. Oxygen consumption and extracellular acidification rates increased over 4 h following LPS stimulation(P < 0.05) regardless of treatment. Similarly, increases in cytoplasmic oxidation(P < 0.001)and nitric oxide production(P < 0.002) were observed after 18 h of LPS stimulation but were unaffected by diet.Conclusions: We infer that enriching diets with arachidonic acid may be an effective means to enhance a stronger innate immunologic response to respiratory challenges in neonatal pigs. However, further work is needed to examine long-term safety, clinical efficacy and economic viability.