利用紫薯粉基质ARTP诱变选育富硒酵母菌株

旨在通过ARTP诱变技术选育出能够高效利用紫薯粉为营养源并富集硒的酿酒酵母菌株,以期开发出新型的富硒紫薯酵母产品,推动紫薯原料的高值化多元利用。以酿酒酵母CICC1015为出发菌株,ARTP诱变结合硒耐受性梯度驯化筛选,选育出能够在含有紫薯粉的培养基中生长,并能够耐受较高浓度亚硒酸钠且进行高效生物转化为有机硒的酵母突变菌株。结果表明:以培养16 h的菌株作为诱变的出发菌株,ARTP处理时间110 s,致死率达到94.2%,既能够较好的保持高突变频率,又利于筛选有益突变菌株。筛选最高耐受200 mg·L^(−1)亚硒酸钠的突变菌株FJH-010,该突变株能在以10%紫薯分为原料的环境下生长良好,生物量达到20.6 g·L^(−1)(干重),硒含量达到4245μg·g^(−1),其中有机硒占比95.3%,硒的转化率达到95.8%,而且遗传稳定性良好,显示了较强的硒富集与转化能力,为进一步开发含有机硒的富硒紫薯酵母产品提供了新途径。

褪黑素对人骨肉瘤细胞p53、c-Myc表达的影响

目的研究褪黑素对人骨肉瘤MG63、U2细胞p53、c-Myc基因表达的调控。方法体外培养MG63、U2细胞,4mmol·L^-1褪黑素干预24h,实时荧光定量PCR及免疫印迹法检测p53及c-Myc基因表达情况。结果褪黑素作用后,U2细胞上调p53基因表达(P<0.05);MG63、U2细胞下调c-Myc蛋白水平表达(P<0.05)。结论褪黑素可能通过上调p53基因及下调c-Myc蛋白表达促进骨肉瘤细胞凋亡。

An Oscillation Condition for an Electrode－separated Piezoelectric Sensor in Non－electrolyte Liquid

n oscillation condition was proposed and experimentally verified for an elec-troderaeparated piezoelectric sensor (ESPS) in non-electrolyte liquid, it was ex-pressed as , where C_s is the solution capaci-tance , R_q, C_o and w are the motional resistance , static capacitance and resonant an-gle frequency of the crystal , respectively. And Y-tgθ, where θ is the phase shift inthe oscillator. The relationships between the minimum cell constant needed for ES-PS to oscillate and each of the following parameters, permittivity, density and vis-cosity of the liquid as well as the oscillator phase shift were discussed. The″ cease-to-oscillate″ frequency of ESPS was measured. The oscillation ability of ESPS in-creases with increasing permittivity or decreasing density and viscosity of the liq-uid. An oscillator with a larger Y value is helpful to drive ESPS.