Optically detected magnetic resonance studies of porcine pancreatic phospholipase A2 binding to a negatively charged substrate analogue

The direct binding of porcine pancreatic phospholipase A2 and its zymogen to 1,2-bis(heptanylcarbamoyl)-rac-glycerol 3-sulfate was studied by optical detection of triplet-state magnetic resonance spectroscopy in zero applied magnetic field. The zero-field splittings of the single Trp3 residue undergo significant changes upon binding of phospholipase A2 to lipid. Shifts in zero-field splittings, characterized mainly by a reduction of the E parameter from 1.215 to 1.144 GHz, point to large changes in the Trp3 local environment which accompany the complexing of phospholipase A2 with lipid. This may be attributed to Stark effects caused by the binding of a charged group near Trp3 in the enzyme-lipid complex. The cofactor, Ca2+, which is strongly bound to the enzyme active site, has an influence on the bonding, as reflected by smaller zero-field splitting shifts. A relatively small change in the Trp environment was observed for the interaction of the zymogen with lipid.     

Effects of SOX2 on Proliferation,Migration and Adhesion of Human Dental Pulp Stem Cells

As a key factor for cell pluripotent and self-renewing phenotypes, SOX2 has attracted scientists’ attention gradually in recent years. However, its exact effects in dental pulp stem cells (DPSCs) are still unclear. In this study, we mainly investigated whether SOX2 could affect some biological functions of DPSCs. DPSCs were isolated from the dental pulp of human impacted third molar. SOX2 overexpressing DPSCs (DPSCs-SOX2) were established through retroviral infection. The effect of SOX2 on cell proliferation, migration and adhesion ability was evaluated with CCK-8, trans-well system and fibronectin-induced cell attachment experiment respectively. Whole genome expression of DPSCs-SOX2 was analyzed with RNA microarray. Furthermore, a rescue experiment was performed with SOX2-siRNA in DPSC-SOX2 to confirm the effect of SOX2 overexpression in DPSCs. We found that SOX2 overexpression could result in the enhancement of cell proliferation, migration, and adhesion in DPSCs obviously. RNA microarray analysis indicated that some key genes in the signal pathways associated with cell cycle, migration and adhesion were upregulated in different degree, and the results were further confirmed with qPCR and western-blot. Finally, DPSC-SOX2 transfected with SOX2-siRNA showed a decrease of cell proliferation, migration and adhesion ability, which further confirmed the biological effect of SOX2 in human DPSCs. This study indicated that SOX2 could improve the cell proliferation, migration and adhesion ability of DPSCs through regulating gene expression about cell cycle, migration and adhesion, and provided a novel strategy to develop seed cells with strong proliferation, migration and adhesion ability for tissue engineering.     

Increased rates of illness and death from asthma in Canada.

Recent rates of illness and death from asthma in Canada and rates of hospital admission/separation for asthma were examined by age group and region. The death rates were higher in 1982-84 than in 1970-72, especially among those aged 15 to 34 years. Increases were also noted in hospital admission/separation rates, especially among those less than 15 years of age. Hospital admission/separation rates were highest in the Maritime provinces and Saskatchewan, whereas death rates were highest in Alberta and Saskatchewan. Examination of death certificates for coding errors and recoding of certificates to a single (8th) revision of the International Classification of Diseases indicated that changes in disease coding and errors in coding did not account for the significant increase in rates of death from asthma for those aged 15 to 34 years. These increases in rates of illness and death from asthma are unexplained and warrant further investigation.     

Important risk factors for death in adults: a 10-year follow-up of the Nutrition Canada survey cohort.

Data on mortality among over 8000 Canadians aged 35 to 79 years who participated in the Nutrition Canada survey are presented. The effects of various risk factors on mortality were assessed with a multivariate Poisson regression analysis. Factors associated with a significantly increased risk of death over a 10-year follow-up period ending in 1981 included cigarette smoking, hypertension and diabetes mellitus. A shallow U-shaped mortality pattern was observed for body mass index and for serum cholesterol level. No statistically significant increases in risk were associated with alcohol consumption. The population attributable risks for smoking, hypertension and diabetes were 39%, 8% and 6% respectively for men and 21%, 12% and 7% respectively for women.     

Quasi-continuum models of twist-like and accordion-like low-frequency motions in DNA.

Formulae for calculating low-frequency twist-like and accordion-like modes of DNA molecules have been derived using a quasi-continuum model. The formulae can be employed in essentially all (viz. A, B, C, D, E, and Z) forms of DNA. Calculated results indicate that the experimentally observed low-frequency modes at 22 cm-1 for the A-form octanucleotide (d[CCCCGGGG]) and at 18 cm-1 for the B-form dodecanucleotide (d[CGCAA ATTTGCG]) may result from accordion-like motions, while those observed at 12 cm-1 and 15 cm-1 may result from combinations of twist-like oscillations excited in the intact segments of B- and A-DNA's, respectively. Frequency shifts in the low-frequency modes observed when DNA molecules undergo conformational changes among different forms are also discussed in terms of the current model.     

抗阿特拉津转基因大豆植株后代的遗传分析

本试验用阿特拉津溶液涂抹、荧光诱导动力学检测、分子杂交等方法对抗阿特拉津转基因大豆植株的后代进行了鉴定,在第二代及第三代中检测到了抗性基因的存在,表明从龙葵中得到的此抗阿特拉津 psbA 基因不仅能导人大豆叶绿体基因组中获得表达,而且可以遗传到后代。     

Disruption of baker's yeast by a new bead mill

Summary A continuous high-speed bead mill of novel design (Sulzer Annu Mill 01) was tested for cell disruption of baker's yeast as a model system. The efficiency of cell disruption was evaluated for the relative amount of released protein. The effects of rotation speed, cell concentration and flow rate of cell suspension on the cell disruption were investigated. The maximum yield of released protein was found to be 2.62 kg protein/L.h. This novel design appears to be more effective than existing commercially available mills.Notations Cs cell concentration (g packed yeast/L) - F flow rate of suspension, mL/min - F_R cumulative residence time distribution - N rotation speed of the rotor (rpm) - P number of passes of suspension through mill - R amount of protein released from cell, mg/g packed yeast - R_m maximum amount of protein released, mg/g packed yeast - t time, s - mean residence time, s