Biotechnological Production of Docosahexaenoic Acid Using Aurantiochytrium limacinum: Carbon Sources Comparison And Growth Characterization

Aurantiochytrium limacinum, a marine heterotrophic protist/microalga has shown interesting yields of docosahexaenoic acid (DHA) when cultured with different carbon sources: glucose, pure and crude glycerol. A complete study in a lab-scale fermenter allowed for the characterization and comparison of the growth kinetic parameters corresponding to each carbon source. Artificial Marine Medium (AMM) with glucose, pure and crude glycerol offered similar biomass yields. The net growth rates (0.10–0.12 h⁻¹), biomass (0.7–0.8 g cells/g Substrate) and product (0.14–0.15 g DHA/g cells) yields, as well as DHA productivity were similar using the three carbon sources. Viable potential applications to valorize crude glycerol are envisioned to avoid an environmental problem due to the excess of byproduct.     

基于PLC伺服控制的甘油雾化喷涂系统设计

根据香烟滤棒的丝束甘油雾化喷涂原理,设计的甘油雾化喷涂系统采用PLC和触摸屏作为主控制器,由甘油桶、温度控制子系统、甘油雾化子系统、喷涂活门和伺服系统组成.研究了活门精确定位的伺服控制,该技术实时跟随丝束的运行速度,由PLC给出活门开度对应的、伺服电机转动所需的、高速脉冲数作为系统的位置给定量,通过位置环、速度环和电流环的三闭环PID控制精确定位活门开度,实现甘油的均匀喷涂,保证甘油喷涂量.给出PLC控制程序流程图,对系统进行了实际运行测试.结果表明：系统运行可靠,滤棒的硬度控制达到国家标准.     

Effects of transforming growth factor‐β1 treatment on muscle regeneration and adipogenesis in glycerol‐injured muscle

Transforming growth factor (TGF)‐β1 is associated with fibrosis in many organs. Recent studies demonstrated that delivery of TGF‐β1 into chemically injured muscle enhances fibrosis. In this study, we investigated the effects of exogenous TGF‐β1 on muscle regeneration and adipogenesis in glycerol‐injured muscle of normal mice. Tibialis anterior (TA) muscles were injured by glycerol injection. TGF‐β1 was either co‐injected with glycerol, as an ‘early treatment’ group, or injected at day 4 after glycerol, as a ‘late treatment’ group and the TA muscles were collected at day 7 after initial injury. Myotube density was significantly lower in the early treatment group than in the glycerol‐injured group (without TGF‐β1 treatment). Moreover, the Oil red O‐positive area was significantly smaller in the early treatment group than in the late treatment group and glycerol‐injured group. Furthermore, TGF‐β1 treatment increased endomysial fibrosis and induced immunostaining of α‐smooth muscle actin. The greater inhibitory effects of early TGF‐β1 treatment than that of late TGF‐β1 treatment during regeneration in glycerol‐injured muscle suggest a more potent effect of TGF‐β1 on the initial stage of muscle regeneration and adipogenesis. Combination of TGF‐β1 with glycerol might be an alternative to enhance muscle fibrosis for future studies.     

The effect of some cryoprotectants on dromedary camel frozen‐thawed semen

The cryopreserved camel semen is often associated with poor quality and fertility. This study aimed to improve the dromedary frozen semen quality by comparing the efficiency of four cryoprotectant agents (CPAs) on sperm freezability. Semen samples were collected from seven male Maghrabi camels, diluted with Shotor diluent supplemented with glycerol (Sh‐G), dimethyl formamide (DMF, Sh‐DF), dimethyl sulfoxide (DMSO, Sh‐DS) or ethylene glycol (EG, Sh‐EG), all at 6% final concentration, and the samples were subjected to cryopreservation. The results revealed the superiority of Sh‐DF over Sh‐G and Sh‐DS in terms of post‐thaw motility (55.83 ± 2.20 vs. 47.50 ± 4.33 and 45.00 ± 2.89%, respectively), sperm membrane (49.00 ± 0.58, 39.33 ± 3.33 and 42.67 ± 1.45%, respectively) and acrosomal integrities (53.00 ± 0.58, 57.33 ± 0.88 and 52.33 ± 1.45%, respectively). Sh‐EG group showed the lowest post‐thaw motility, plasma membrane and acrosome integrities (12.50 ± 1.44, 22.67 ± 1.45 and 30.67 ± 1.45, respectively). In conclusion, the protocols of dromedary camel semen cryopreservation could be enhanced using 6% DMF as a cryoprotectant agent.     

Correction for sample free glycerol is needed for accurate measurement of plasma triglyceride concentrations in miniature Swine

Methods for the measurement of plasma or serum triglyceride concentrations usually quantify the glycerol released by enzymatic hydrolysis of the triglyceride molecule. Any free glycerol in the sample is measured erroneously as triglyceride in these methods. As miniature swine have been used commonly for comparative studies of plasma lipoprotein lipids, this study was conducted to assess the need for free glycerol correction of plasma triglyceride measurements by comparing glycerol-blank corrected and non-corrected total plasma triglyceride concentrations from fasted minipigs. Fasting plasma free glycerol concentrations range from 9 to 14 mg/dl. The mean +/- SD (n = 16) glycerol-blank corrected total plasma triglyceride value (77 +/- 8 mg/dl) was significantly (p < 0.001) less than the uncorrected measurement value (189 +/- 12 mg/dl). Poor correlation (r = 0.24) between corrected and uncorrected total plasma triglyceride measurements suggests that mathematic correction by a constant correction factor would yield inaccurate results for miniature swine. Free glycerol blanking is essential for determination of the true total plasma triglyceride concentration.     

葡萄糖、丙三醇和盐对厚唇裂腹鱼精子活力的调控研究

为了探究厚唇裂腹鱼(Schizothorax irregularis)精子活力的调控规律,提高受精率和苗种生产效率,文章采用显著性检验和响应面法,研究了葡萄糖、丙三醇和3种盐对厚唇裂腹鱼精子活力的单项调控和复合项调控作用。结果表明,葡萄糖为433.7 kPa时厚唇裂腹鱼精子的快速运动时间(FT)最大(37.00 s),显著高于其他组(P<0.05);丙三醇为506.7 kPa时厚唇裂腹鱼精子的FT最大(32.33 s),与416.3 kPa组无差异,但显著高于其他组(P<0.05);氯化钠为431.4 kPa时厚唇裂腹鱼精子的FT最大(35.00 s),与348.8 kPa组无差异,但显著高于其他组(P<0.05);氯化钾对精子的激活效果不明显,氯化镁则有抑制效果;建立了厚唇裂腹鱼精子FT与葡萄糖、丙三醇和氯化钠的拟合方程,该方程的一次效应、二次效应均极显著(P<0.01),交互效应显著(P<0.05);模型优化配方为氯化钠164.78 kPa、丙三醇216.55 kPa、葡萄糖208.43 kPa,理论FT为68.24 s。运用响应面法优化的激活液配方,能有效提高该鱼的精子活力。     

不同处理对三色堇花瓣护色效果的影响

以3个不同品种新鲜的三色堇花材为试验材料,研究了柠檬酸、氯化镁和甘油用不同方法对三色堇花瓣保色、护色效果的影响。结果表明,采用B_2试剂用重压干燥法对XXL-YB-1-1品种的处理效果较好;采用B_2试剂用重压干燥法对DSRFB品种的处理效果较好,采用B_3试剂用微波炉干燥法对RIRB品种的处理效果较好。     

1，3—丙二醇发酵生产的研究进展

对国内外1,3－丙二醇（1，3－PD）发酵生产的研究成果进行了综述，包括其发酵机理、发酵方式及基因工程菌生产1，3－PD的现状等，探讨了1，3－PD发酵生产的发展前景。