Dietary n−3 FA modulate long and very long chain FA content, rhodopsin content, and rhodopsin phosphorylation in rat rod outer segment after light exposure

A previous study has shown that the long and very long chain FA (VLCFA) content of the rat retina responds to changes in dietary n−6/n−3 ratio of the fat fed (1). The present study tested whether similar changes in these FA are associated with alterations in rhodopsin content and rhodopsin phosphorylation after light treatment. Weanling rats were fed diets containing 20% (w/w, 40% energy) fat with either high (4.8%, w/w) or low (1.2%, w/w) n−3 FA. After 6 wk of feeding, half of the animals in each group were exposed to light for 48 h at 350 lx or were kept in complete darkness. In the rod outer segment, the high n−3 diet treatment increased the level of 20∶5n−3 and 22∶6n−3 and reduced the levels of 20∶4n−6 and 24∶4n−6 in PC, PE, and PS. After the feeding of a high n−3 FA diet, total n−3 pentaenoic VLCFA from C₂₄ to C₃₄ increased in PC, whereas the n−6 tetra- and pentaenoic VLCFA decreased. No changes occurred in n−3 hexaenoic VLCFA regardless of the level of 22∶6n−3 in the diet. After light exposure, animals fed a high n−3 FA diet showed reduction in 22∶6n−3 as well as in n−6 and n−3 VLCFA in PC. FFA and TG fractions contained increased levels of both 20∶4n−6 and 22∶6n−3 after light exposure. Dark-adapted rhodopsin content and rhodopsin phosphorylation in the rod outer segment of rats fed the low n−3 FA diet were higher than in animals fed a high n−3 FA diet. After light exposure, animals fed the low n−3 FA diet lost more rhodopsin compared to animals fed the high n−3 FA diet, resulting in less phosphorylation of rhodopsin. Results indicate that the FA composition, rhodopsin content, and phosphorylation in visual cells is influenced by the dietary n−3 FA fed as well as by light exposure. The results also imply that 22∶6n−3 may not be the precursor for synthesis of hexaenoic VLCFA.     

Effect of piezo-driven injection system on the macroscopic and microscopic atomization characteristics of diesel fuel spray

This study was conducted to determine the macroscopic and fuel atomization characteristics of a piezo-driven injection system and to compare it with a solenoid-driven injection system in a common-rail diesel engine.In order to obtain the macroscopic characteristics of fuel spray, the spray development process was visualized using the spray visualization system composed of a Nd:YAG laser and an ICCD camera. The injection characteristics of the fuel spray such as injection rate and injection delay profile were investigated under the various injection conditions. The injection and atomization characteristics were investigated in terms of the droplet mean axial and radial velocities, droplet diameter, and droplet distributions obtained using a phase Doppler particle analyzer (PDPA) system.It was found that the piezo-driven injection system has a short injection delay and quickly reaches the maximum injection rate compared to the solenoid-driven injection system. Spray tip penetration makes little difference; however, the spray cone angle of the piezo-driven injector is larger than that of the solenoid-driven injector. The atomization performance of the piezo-driven injection system is superior to that of the solenoid-driven injection system due to a faster response time and higher injection rate.     

Synthesis and optically acid-sensory properties of novel polyoxadiazole derivatives

New organo-soluble and blue-emissive fluorene-based polyoxadiazoles, PFO_x and PFO_xEH, exhibit colorimetric and fluorescent acid-sensory properties to a strong acid due to the weak basicity of imine-type nitrogen atom(s) in an 1,3,4-oxadiazole ring. To further investigate their protonation with an acid, ¹H NMR spectroscopy and AM1 semiempirical quantum-mechanics are utilized as well as UV-visible absorption and fluorescence spectroscopies. These investigations indicate the protonation does not proceed thermodynamically but kinetically at the initial stage of the complex formation of an acid and an oxadiazole ring in the polymer backbone.     

Improvement of lactulose synthesis through optimization of reaction conditions with immobilized β-galactosidase

Kluyveromyces lactis β-galactosidase was immobilized on silica gels using a covalent bonding method. To improve lactulose synthesis using immobilized β-galactosidase, the optimal reaction conditions, such as lactose and fructose concentrations, pH and ionic strength of the buffer, loading amount of the enzyme and temperature, were determined. Lactulose synthesis using the immobilized β-galactosidase was markedly improved after optimization of the reaction conditions. When the lactulose synthesis was carried out at 47 °C using 40% (w/v) lactose, 20% (w/v) fructose and immobilized β-galactosidase of 12 U/ml in 50 mM sodium phosphate buffer at pH 7.5, the lactulose concentration and specific productivity were 15.80 g/l and 1.32 mg/U·h, respectively. In addition, when the immobilized β-galactosidase was reused for lactulose synthesis, its catalytic activity retained 60.5% after 10 reuses.     

Porcine G0/G1 Switch Gene 2 (G0S2) Expression is Regulated During Adipogenesis and Short-Term In-Vivo Nutritional Interventions

Adipose triglyceride lipase (ATGL), catalyzing the initial step of hydrolysis of triacylglycerol (TAG) in adipocytes, has been known to be inhibited by G0/G1 switch gene 2 (G0S2). In this study, we report the porcine G0S2 cDNA and amino acid sequences as well as the expression level of porcine G0S2. The porcine G0S2 mRNA was abundantly expressed in adipose tissue and liver among various tissues. In adipose tissue, porcine G0S2 expression was 16-fold higher in the fat cell fraction than the stromal vascular fraction. The G0S2 level increased significantly during adipogenesis in vitro and in vivo. These data indicate that G0S2 expression is closely associated with lipid accumulation and adipogenesis. Considering G0S2 as an inhibitor of cell proliferation, the relatively low levels of G0S2 in preadipocytes and adipose tissues of fetal and neonatal pigs compared to adipocytes and adipose tissues of adult pigs may allow the fast cell proliferation rates. Further studies showed that a short-term 24-h fast down-regulated G0S2 expression and increased ATGL expression in adipose tissue; however, a long-term calorie restriction for 8 days had no influence on the level of G0S2 but increased ATGL expression. Therefore, porcine G0S2, which is both a negative regulator of ATGL-mediated lipolysis and cell proliferation in adipose tissue, can be down-regulated in vivo by a short-term 24-h fast followed by increased ATGL-mediated lipolysis.