红豆杉抗苯丙氨酸细胞系的筛选及悬浮培养特性

通过胁迫筛选法筛选红豆杉抗－苯丙氨酸细胞变异系,并比较了该细胞系与同步培养的原型细胞系悬浮培养的几项生理指标,结果表明,抗苯丙氨酸细胞系的紫杉醇含量显著高于原型细胞系的3－5倍,并且抗性细胞系的生长速率,细胞活性,pH值,胞内可溶性糖含量及褐变强度均与原型细胞系存在显著差别。     

股前外侧穿支皮瓣与胸腹带蒂皮瓣对手外伤组织缺损修复的应用效果及对创面愈合程度的影响

摘要 目的：探讨股前外侧穿支皮瓣与胸腹带蒂皮瓣对手外伤组织缺损修复的应用效果及对创面愈合程度的影响。方法：选取我院2018年12月到2020年12月共收治的119例手外伤组织缺损患者作为研究对象,随机分为2组,分别为对照组（n=59,应用胸腹带蒂皮瓣修复术）和观察组（n=60,应用股前外侧穿支皮瓣修复术）。对比两组患者治疗优良率,对比两组患者治疗前后手部创面面积、创面愈合程度以及组织愈合时间,对比两组患者治疗后的Jamar握力、TAM和DASH评分情况,对比两组患者的皮瓣成活率、皮瓣危象率和血管吻合时间。结果：通过对比两组患者治疗优良率发现,观察组患者优的人数为21例、良为35例,优良率为93.33%,对照组患者优的人数为16例,良为30例,优良率为77.97%,观察组高于对照组（P＜0.05）;治疗后,与对照组相比,观察组患者的手部创面面积、组织愈合时间和DASH评分显著减少,创面愈合程度以及TAM与Jamar握力显著增加（P＜0.05）;通过对比两组患者的皮瓣成活率、术后皮瓣危象率以及血管吻合时间发现,两组患者的术后皮瓣危象率、血管吻合时间对比无明显差异（P＞0.05）,两组患者的术后皮瓣成活率对比差异显著,观察组明显高于对照组（P＜0.05）。结论：对手外伤组织缺损患者应用股前外侧穿支皮瓣与胸腹带蒂皮瓣修复术均具有明显的修复效果,但是应用股前外侧穿支皮瓣能够提升治疗效果,提升患者创面愈合程度减少愈合时间,提升患者手部运动情况,提升术后皮瓣成活率,值得临床应用推广。     

腰椎旁神经阻滞联合超短波对腰椎间盘突出症患者疼痛及腰背肌生物力学性能的影响

目的:探讨腰椎旁神经阻滞联合超短波对腰椎间盘突出症疼痛及腰背肌生物力学性能的影响。方法:选择我院2014年2月~2016年8月收治的98例腰椎间盘突出症患者,按抽签法分组对照组与研究组。对照组采用腰椎旁神经阻滞治疗,研究组基于对照组加用超短波治疗。观察两组的临床疗效、治疗前后视觉模拟评分(VAS)、60°/s角速、120°/s角速平均功率(AP)、峰力矩(PT)、腰背屈/伸比值(F/E)、血清P物质(SP)、β-内啡肽(β-EP)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)水平的变化及不良反应的发生情况。结果:研究组总有效率为95.91%,显著高于对照组,差异有统计学意义(P0.05)。治疗后,两组F/E值、血清SP、IL-6、TNF-α水平均较治疗前显著降低,且研究组以上指标均明显低于对照组,两组AP、PT、血清β-EP水平均较治疗前明显上升,且研究组以上指标显著高于对照组,差异均有统计学意义(P0.05)。两组不良反应的发生率比较差异无统计学意义(P0.05)。结论:腰椎旁神经阻滞联合超短波治疗腰椎间盘突出症的效果明显优于单用腰椎旁神经阻滞治疗,其可有效缓解疼痛及改善腰背肌生物力学性能,并减轻炎症反应。     

葡萄糖对ICR小鼠胚胎体外发育的影响

研究葡萄糖在小鼠早期胚胎体外发育中的作用。实验1将6—8周龄的ICR雌鼠超数排卵后与公鼠交配,收集1-细胞放入含0(对照组)、0.5、1、3、5、10mmol/L葡萄糖的CZB中培养;实验2将从超排的ICR雌鼠输卵管内收集的1-细胞放入无糖CZB中培养,分别于1细胞、2细胞、4细胞、桑椹胚阶段移入含3.0mmol/L葡萄糖(最适浓度)的CZB中,培养24h后又移回到无糖CZB中(桑椹胚阶段除外)继续培养以及整个胚胎培养过程均在含糖CZB中,对照组胚胎培养全程均在无糖CZB中。每组胚胎于37℃、5%CO2培养箱中培养120h,每24h在倒置显微镜下观察胚胎发育情况,分别计算2-细胞率、4-细胞率、桑椹胚率、囊胚率和孵化率,并进行囊胚细胞计数。结果显示,小鼠胚胎在含糖CZB中与在无糖CZB中4-细胞发育率无差异;含糖CZB中囊胚率显著高于对照组;3.0mmol/L浓度组囊胚细胞数显著高于其余组;2-细胞至4-细胞、4-细胞至桑椹胚前添加葡萄糖囊胚率显著高于对照组,1-细胞至2-细胞、桑椹胚及其以后阶段添加葡萄糖囊胚率与对照组无差异。实验证实,在ICR小鼠胚胎体外培养中加入葡萄糖不会导致2-细胞阻滞;葡萄糖浓度增至10mmol/L对ICR小鼠胚胎无毒性作用;ICR小鼠胚胎体外培养的最适葡萄糖浓度为3.0mmol/L;2-细胞至4-细胞、4-细胞至桑椹胚前添加葡萄糖是必要的。     

The N-terminal region of the starch-branching enzyme from Phaseolus vulgaris L. is essential for optimal catalysis and structural stability

Starch-branching enzymes (SBEs) play a pivotal role in determining the fine structure of starch by catalyzing the syntheses of alpha-1,6-branch points. They are the members of the alpha-amylase family and have four conserved regions in a central (beta/alpha)8 barrel, including the catalytic sites. Although the role of the catalytic barrel domain of an SBE is known, that of its N- and C-terminal regions remain unclear. We have previously shown that the C-terminal regions of the two SBE isozymes (designated as PvSBE1 and PvSBE2) from kidney bean (Phaseolus vulgaris L.) have different roles in branching enzyme activity. To understand the contribution of the N-terminal region to catalysis, six chimeric enzymes were constructed between PvSBE1 and PvSBE2. Only one enzyme (1Na/2Nb)-II, in which a portion of the N-terminal region of PvSBE2 was substituted by the corresponding region of PvSBE1, retained 6% of the PvSBE2 activity. The N-terminal truncated form (DeltaN46-PvSBE2), lacking 46 N-terminal residues of PvSBE2, lost enzyme activity and stability to proteolysis. To investigate the possible function of this region, three residues (Asp-15, His-24, and Arg-28) among these 46 residues were subjected to site-directed mutagenesis. The purified mutant enzymes showed nearly the same K(m) values as PvSBE2 but had lower V(max) values and heat stabilities than PvSBE2. These results suggest that the N-terminal region of the kidney bean SBE is essential for maximum enzyme activity and thermostability.     

A secondary xylan-binding site enhances the catalytic activity of a single-domain family 11 glycoside hydrolase

Bacillus circulans xylanase (BcX) is a single-domain family 11 glycoside hydrolase. Using NMR-monitored titrations, we discovered that an inactive variant of this enzyme, E78Q-BcX, bound xylooligosaccharides not only within its pronounced active site (AS) cleft, but also at a distal surface region. Chemical shift perturbation mapping and affinity electrophoresis, combined with mutational studies, identified the xylan-specific secondary binding site (SBS) as a shallow groove lined by Asn, Ser, and Thr residues and with a Trp at one end. The AS and SBS bound short xylooligosaccharides with similar dissociation constants in the millimolar range. However, the on and off-rates to the SBS were at least tenfold faster than those of kon approximately 3x10(5) M(-1) s(-1) and koff approximately 1000 s(-1) measured for xylotetraose to the AS of E78Q-BcX. Consistent with their structural differences, this suggests that a conformational change in the enzyme and/or the substrate is required for association to and dissociation from the deep AS, but not the shallow SBS. In contrast to the independent binding of small xylooligosaccharides, high-affinity binding of soluble and insoluble xylan, as well as xylododecaose, occurred cooperatively to the two sites. This was evidenced by an approximately 100-fold increase in relative Kd values for these ligands upon mutation of the SBS. The SBS also enhances the activity of BcX towards soluble and insoluble xylan through a significant reduction in the Michaelis KM values for these polymeric substrates. This study provides an unexpected example of how a single domain family 11 xylanase overcomes the lack of a carbohydrate-binding module through the use of a secondary binding site to enhance substrate specificity and affinity.     

Stochastic von Bertalanffy models, with applications to fish recruitment

We consider three individual-based models describing growth in stochastic environments. Stochastic differential equations (SDEs) with identical von Bertalanffy deterministic parts are formulated, with a stochastic term which decreases, remains constant, or increases with organism size, respectively. Probability density functions for hitting times are evaluated in the context of fish growth and mortality. Solving the hitting time problem analytically or numerically shows that stochasticity can have a large positive impact on fish recruitment probability. It is also demonstrated that the observed mean growth rate of surviving individuals always exceeds the mean population growth rate, which itself exceeds the growth rate of the equivalent deterministic model. The consequences of these results in more general biological situations are discussed.     

Harvest prediction in ‘Algerie’ loquat

Plant phenology is in great measure driven by air temperature. To forecast harvest time for ‘Algerie’ loquat accurately, the growing degree days (GDD) needed from bloom to ripening were determined using data from nine seasons. The methods proposed by Zalom et al. (Zalom FG, Goodell PB, Wilson LT, Barnett WW, Bentley W, Degree-days: the calculation and use of heat units in pest management, leaflet no 21373, Division Agriculture and Natural Resources, University of California 10 pp, 1983) were compared as regards their ability to estimate heat summation based on hourly records. All the methods gave remarkably similar results for our cultivation area, although the double-sine method showed higher performance when temperatures were low. A base temperature of 3°C is proposed for ‘Algerie’ loquat because it provides a coefficient of variation in GDD among seasons of below 5%, and because of its compatibility with loquat growth. Based on these determinations, ‘Algerie’ loquat requires 1,715 GDD from bloom to harvest; under our conditions this heat is accumulated over an average of 159 days. Our procedure permits the ‘Algerie’ harvest date to be estimated with a mean error of 4.4 days (<3% for the bloom-harvest period). GDD summation did not prove superior to the use of the number of calendar days for predicting ‘Algerie’ harvest under non-limiting growing conditions. However, GDD reflects the developmental rate in water-stressed trees better than calendar days. Trees under deficit irrigation during flower development required more time and more heat to ripen their fruits.     

一类无穷时滞微分系统的周期解和全局吸引性

考虑如下具有无穷时滞的微分系统:x′(t)=A(t,x(t))x(t) (integral from -∞to 0)f(t,s,x(s t))ds (sum from i=1 to p) fi(t,x(t-T_i(t)))的周期解.利用重合度理论和构造适当的Lyapunov泛函得到上述系统周期解存在性和全局吸引性的充分条件,推广了已有的结论,得到了新的结果.     

A high-throughput strategy to screen 2D crystallization trials of membrane proteins

Electron microscopy of two-dimensional (2D) crystals has demonstrated potential for structure determination of membrane proteins. Technical limitations in large-scale crystallization screens have, however, prevented a major breakthrough in the routine application of this technology. Dialysis is generally used for detergent removal and reconstitution of the protein into a lipid bilayer, and devices for testing numerous conditions in parallel are not readily available. Furthermore, the small size of resulting 2D crystals requires electron microscopy to evaluate the results and automation of the necessary steps is essential to achieve a reasonable throughput. We have designed a crystallization block, using standard microplate dimensions, by which 96 unique samples can be dialyzed simultaneously against 96 different buffers and have demonstrated that the rate of detergent dialysis is comparable to those obtained with conventional dialysis devices. A liquid-handling robot was employed to set up 2D crystallization trials with the membrane proteins CopA from Archaeoglobus fulgidus and light-harvesting complex II (LH2) from Rhodobacter sphaeroides. For CopA, 1 week of dialysis yielded tubular crystals and, for LH2, large and well-ordered vesicular 2D crystals were obtained after 24 h, illustrating the feasibility of this approach. Combined with a high-throughput procedure for preparation of EM-grids and automation of the subsequent negative staining step, the crystallization block offers a novel pipeline that promises to speed up large-scale screening of 2D crystallization and to increase the likelihood of producing well-ordered crystals for analysis by electron crystallography.