增强UV-B辐射对蚕豆幼苗叶片抗氧化保护系统的影响

采用人工增强UV-B辐射的方法,研究了在不同强度UV-B辐射下,蚕豆幼苗保护酶活性及抗氧化物质含量的变化。结果表明:在本试验条件下,随辐射强度增加,POD活性上升,CAT活性下降,短期低强度的UV-B辐射下ASA含量增加,增强的UV-B辐射显著抑制类胡萝卜素的合成。     

椭圆背角无齿蚌肝脏的组织学观察

运用组织学方法研究了椭圆背角无齿蚌肝脏的组织学结构。结果表明,肝脏是一对大型的腺体,消化腺为复管状腺,由分泌管、导管、连接管及间质构成,腺管上皮有消化细胞和嗜碱性细胞2种类型,消化细胞内含众多的囊泡和颗粒。     

Acute Renal Failure in Liver Transplant Patients: Indian Study

The acute renal failure is the frequent medical complication observed in liver transplant patients. The objective of this study was to determine the cause of acute renal failure in post liver transplant patients. A total of 70 patients who underwent (cadaveric 52, live 18) liver transplantation were categorized based on clinical presentation into two groups, namely hepatorenal failure (HRF, n = 29), and Hepatic failure (HF, n = 41). All the patients after the liver transplant had received tacrolimus, mycophenolate and steroids. We analyzed the modification of diet in renal disease, (MDRD) serum urea, creatinine and albumin before and after 5th and 30th day of liver transplant and data was categorized into survivors and non-survivors group. In HRF survivor group, serum creatinine, and urea levels were high and, albumin, MDRD were low in pre- transplant and reached to normal levels on 30th day of post transplant, and 79.3 % of patients in this group showed resumption of normal kidney function. On the contrary in HRF nonsurvivor group, we did not observed any significant difference and 20.7 % of patients showed irreversible changes after the liver transplant. In HF survivor group, 82.9 % of liver failure patients did not show any deviation in serum creatinine, urea, albumin and MDRD, whereas in HF non survivor group, 17.1 % of liver failure patients who had HCV positive before the transplant developed acute renal failure. The levels of creatinine, urea, albumin and MDRD were normal before the transplant and on day 30th, the levels of albumin and MDRD were significantly low whereas serum urea, creatinine levels were high. In conclusion, based on these observations, an diagnosis and treatment of Acute renal failure is important among the liver transplantation cases in the early postoperative period.     

肝癌患者血清SOD及MDA的变化研究

目的:探索肝癌患者血清SOD、MDA的变化。对肝癌患者26例和健康对照组30例。方法:对肝癌患者均应用改良TBA微量法测定血清丙二醛(MDA)、以黄嘌呤氧化酶法测定超氧化物歧化酶(SOD)水平的变化。结果:肝癌组患者血清MDA水平显著高于对照组(P<0.01),而血清SOD水平显著低于对照组(P<0.01)。结论:提示肝癌患者存在明显的抗氧化能力障碍,通过血清MDA、SOD水平的检测,可为肝癌的临床治疗及疗效观察提供一定的依据。     

Activity of Hydrolytic Enzymes in Various Regions of Normal Human Brain Tissue

The activity of six hydrolytic enzymes-carboxyl esterase, acid phosphatase, alkaline phosphatase, β-galactosidase, β-glucosidase and β-hexosaminidase, were studied in different regions of the normal human brain tissue obtained at autopsy. Protein estimation and activities of the hydrolytic enzymes with respective substrates were assayed by spectrophotometric and spectroflourometric methods. Amongst the eight regions of the brain-frontal, parietal, occipital, temporal, thalamus, cerebellum and hippocampus, the pineal gland showed highest activity for all hydrolytic enzymes studied except for carboxyl esterase. Among six hydrolases studied, hexosaminidase exhibited highest activity in all regions of the human brain while alkaline phosphatase activity was the least amongst all regions studied. A majority of the enzymes studied showed higher activity in gray matter as compared to the white matter except acid phosphatase and β-glucosidase which exhibited higher activity in the white matter. The most significant finding in the present study was the high activity of all hydrolytic enzymes noted in the pineal gland as compared to all other regions of the human brain. Such a finding has not been hitherto reported earlier in human brain tissue samples. If the specific activities of these enzymes are to be considered as any functional index, then pineal gland may be more metabolically active tissue with respect to the hydrolytic function as compared to the other regions of the brain.     

烤烟种子萌发活动中有关酶及物质动态研究

以K326品种为材料,探索烤烟种子萌发活动中有关酶活性及相关物质的变化动态,结果表明：呼吸强度、淀粉酶与可溶性总糖和还原糖,蛋白酶与总游离氨基酸,脂肪酶与脂肪酸,以及过氧化物酶（POD）、多酚氧化酶（PPO）、可溶性蛋白质、脯氨酸（pro）、丙二醛（MDA）等的活性或含量都随种子萌发进程呈上升趋势,虽然其间有所起伏,但高峰期大都在第84～168h之间,仅POD、总游离氨基酸与MDA含量在萌发中期才开始明显上升,直到萌发结束时达高峰期．淀粉酶、蛋白酶、脂肪酶活性与各自催化水解的产物含量相关性显著,粗脂肪含量随萌发进程而下降,与脂肪酸含量呈极显著负相关．萌发集中在46～68h,发芽势96％,同步指数0．94．萌发动态符合Logistic生长曲线方程．     

Chlorella vulgaris triggers apoptosis in hepatocarcinogenesis-induced rats

Chlorella vulgaris (CV) has been reported to have antioxidant and anticancer properties. We evaluated the effect of CV on apoptotic regulator protein expression in liver cancer-induced rats. Male Wistar rats (200-250 g) were divided into eight groups: control group (normal diet), CDE group (choline deficient diet supplemented with ethionine in drinking water to induce hepatocarcinogenesis), CV groups with three different doses of CV (50, 150, and 300 mg/kg body weight), and CDE groups treated with different doses of CV (50, 150, and 300 mg/kg body weight). Rats were sacrificed at various weeks and liver tissues were embedded in paraffin blocks for immunohistochemistry studies. CV, at increasing doses, decreased the expression of anti-apoptotic protein, Bcl-2, but increased the expression of pro-apoptotic protein, caspase 8, in CDE rats, which was correlated with decreased hepatoctyes proliferation and increased apoptosis as determined by bromodeoxy-uridine (BrdU) labeling and terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) assay, respectively. Our study shows that CV has definite chemopreventive effect by inducing apoptosis via decreasing the expression of Bcl-2 and increasing the expression of caspase 8 in hepatocarcinogenesis-induced rats.     

Probing transient protein-mediated DNA linkages using nanoconfinement

We present an analytic technique for probing protein-catalyzed transient DNA loops that is based on nanofluidic channels. In these nanochannels, DNA is forced in a linear configuration that makes loops appear as folds whose size can easily be quantified. Using this technique, we study the interaction between T4 DNA ligase and DNA. We find that T4 DNA ligase binding changes the physical characteristics of the DNA polymer, in particular persistence length and effective width. We find that the rate of DNA fold unrolling is significantly reduced when T4 DNA ligase and ATP are applied to bare DNA. Together with evidence of T4 DNA ligase bridging two different segments of DNA based on AFM imaging, we thus conclude that ligase can transiently stabilize folded DNA configurations by coordinating genetically distant DNA stretches.     

Extracellular expression in Bacillus subtilis of a thermostable Geobacillus stearothermophilus lipase

BackgroundThe extracellular expression of enzymes in a secretion host such as Bacillus subtilis is a useful strategy in reducing the cost of downstream processing of industrial enzymes. Here, we present the first report of the successful extracellular expression in Bacillus subtilis WB800 of Geobacillus stearothermophilus lipase (T1.2RQ), a novel industriallydesirable thermostable lipolytic enzyme which has an excellent hydrolytic and transesterification activity. Signal peptides of α-amylase, extracellular protease, and lipase A, as well as two different promoters, were used in the secretion and expression of lipase T1.2RQ.ResultsLipase activity assay using p-nitrophenyl laurate showed that all three signal peptides directed the secretion of lipase T1.2RQ into the extracellular medium. The signal peptide of lipase A, resulted in the highest extracellular yield of 5.6 U/ml, which corresponds to a 6-fold increase over the parent Bacillus subtilis WB800 strain. SDS-PAGE and zymogram analysis confirmed that lipase T1.2RQ was correctly processed and secreted in its original size of 44 kDa. A comparison of the expression levels of lipase T1.2RQ in rich medium and minimal media showed that the enzyme was better expressed in rich media, with up to an 8-fold higher yield over minimal media. An attempt to further increase the lipase expression level by promoter optimization showed that, contrary to expectation, the optimized promoter exhibited similar expression levels as the original one, suggesting the need for the optimization of downstream factors.ConclusionsThe successful extracellular secretion of lipase T1.2RQ in Bacillus subtilis represents a remarkable feat in the industrial-scale production of this enzyme.How to cite: Ridwan E, Suwanto A, Thenawidjaja M. Extracellular expression in Bacillus subtilis of a thermostable Geobacillus stearothermophilus lipase. Electron J Biotechnol 2021;53. https://doi.org/10.1016/j.ejbt.2021.07.003     

昆虫壳聚糖对运动训练大鼠肝脏抗氧化酶系与SOD基因表达的影响

目的:报道了补充虫源壳聚糖对大鼠肝脏抗氧化酶系和SOD基因表达影响的研究结果。方法:对大负荷游泳训练大鼠补充剂量分别为各组平均体重的0.5 g/kg、1.0 g/kg和2.0 g/kg的虫源壳聚糖,在8周大负荷训练结束后测定肝脏抗氧化酶系的活性,并分析不同处理组动物肝脏SOD基因表达水平差异。结果:补充虫源壳聚糖能够显著提高抗氧化酶系活性,虫源壳聚糖0.5 g/kg补充组与单纯大负荷运动组相比,SOD、CAT和GSH-Px酶活性显著升高(P<0.05);虫源壳聚糖1.0 g/kg和2.0 g/kg补充组与单纯大负荷运动组相比:SOD、CAT和GSH-Px酶活性升高极为显著(P<0.01)。MDA含量在不同水平虫源壳聚糖补充组均显著低于单纯大负荷运动组(P<0.01)。对SOD基因表达分析结果显示,SOD酶活性的升高与其基因表达水平提高呈正相关。结论:补充虫源壳聚糖有助于提高训练大鼠的运动肝脏抗氧化酶系活性,活性的提高与相关编码基因的表达水平提高有关。