利用黑斑双鳍电鳐构建实验性自身免疫性重症肌无力小鼠模型

目的建立符合国际化的临床前实验标准的实验性自身免疫性重症肌无力(experimental autoimmune myasthenia gravis, EAMG)动物模型。方法参照文献报道的方法并改进后,从电鳐电器官提取乙酰胆碱受体(acetylcholine receptor,AchR)蛋白纯品,并采用SDS凝胶电泳蛋白定性鉴定及BCA法蛋白定量;用纯化的蛋白主动免疫C57BL/6小鼠,共免疫3次(分别于第1天、第30天、第60天),进行EAMG小鼠临床评分、体重、血清AchR抗体含量、新斯的明试验、肌电图等综合评价。结果 EAMG模型组与佐剂组比较,自第三周开始发病,平均临床评分显著上升(P<0.01);发病小鼠体重显著减轻(P<0.01);新斯的明试验阳性;血清AchR抗体含量明显增加(P<0.01);肌电图重复电刺激实验阳性。结论从黑斑双鳍电鳐的电器官提取、纯化AchR蛋白成功诱导C57BL/6 EAMG小鼠模型,为进一步研究重症肌无力创造了良好条件。     

表施和混施污泥对团花根系生长的影响

林地利用被认为是污泥资源化利用的重要方式,但施用污泥对林木根系生长的影响报道较少。本研究通过根箱试验,分析表施和混施10%污泥对速生树种团花不同土层根系形态、土壤pH值和电导率动态变化及根系重金属含量的影响,并拟合土壤pH值、电导率和根系重金属含量与根长的关系。结果表明: 与不施污泥(对照)相比,混施污泥显著抑制了团花根长、根表面积和根体积增长,混施污泥120和240 d后,0～20 cm土层总根长分别为不施污泥的76.9%和67.4%;表施污泥对团花根长和根表面积的影响不显著,但显著提高了根体积。混施污泥显著提高了土壤pH值和电导率及根系重金属含量,混施污泥0～20和20～40 cm土层根系镉含量分别是不施污泥的11.5和10.0倍。线性回归拟合分析显示,不同处理0～20 cm土层的电导率与根长均呈显著负相关;表施和混施污泥根系镉含量与根长呈极显著负相关。上述结果表明,混施污泥抑制了团花根系生长,这可能是由于混施污泥提高了土壤电导率和根系镉含量所致,而表施污泥对团花根系生长的作用不明显。     

Use of Ψ<Superscript>α</Superscript>-ETOs in the unified treatment of electronic attraction,electric field and electric field gradient multicenter integrals of screened Coulomb potentials over Slater orbitals

In this study, using complete orthonormal sets of -ETOs (where =1, 0, –1, –2, ...)introduced by the author, a large number of series expansion formulae for the multicenter electronic attraction (EA), electric field (EF) and electric field gradient (EFG) integrals of the Yukawa-like screened Coulomb potentials (SCPs) is presented through the new central and noncentral potentials and the overlap integrals with the same screening constants. The final results obtained are valid for arbitrary locations of STOs and their parameters.An erratum to this article can be found at     

Determinants of sperm transfer in the scorpionfly Panorpa cognate: male variation, female condition and copulation duration

Recent studies suggest that sperm production and transfer may have significant costs to males. Male sperm investment into a current copulation may therefore influence resources available for future matings, which selects for male strategic mating investment. In addition, females may also benefit from actively or passively altering the number of sperm transferred by males. In the scorpionfly Panorpa cognata, the number of sperm transferred during copulation depended on copulation duration and males in good condition (residual weight) copulated longer and also transferred more sperm. Moreover, sperm transferred and stored per unit time was higher in copulations with females in good condition than in copulations with females in poor condition. Males varied greatly and consistently in their sperm transfer rate, indicative of costs associated with this trait. The duration of the pairing prelude also varied between males and correlated negatively with the male's sperm transfer rate, but no other male character correlated significantly with male sperm transfer rate. The results are consistent with strategic mating effort but sperm transfer could also be facilitated by the physical size of females and/or females in good condition may be more cooperative during sperm transfer.     

Strong bending of purple membranes in the M-state

Structure changes of purple membranes during the photocycle were analysed in solution by measurements of the electric dichroism. The D96N-mutant was used to characterize the M-state at neutral pH. The transition from the resting state to 61% photo-stationary M-state is associated with a strong reduction of the dichroism decay time constant by a factor of approximately 2. Because the change of the time constant is independent of the bacteriorhodopsin concentration, the effect is not attributed to light-induced dissociation but to light-induced bending of purple membranes. After termination of light-activation the dichroism decay of the resting state is restored with a time constant close to that of the M-state decay, which is more than two orders of magnitude slower than proton transfer to the bulk. Thus, bending is not due to asymmetric protonation but to the structure of the M-state. A very similar reduction of decay time constants at a corresponding degree of light-activation was found for wild-type bacteriorhodopsin at pH-values 7.8-9.3, where the lifetime of the M-state is extended. Light-induced bending is also reflected in changes of the stationary dichroism, whereas the overall permanent dipole moment remains almost constant, suggesting compensation of changes in molecular and global contributions. Bead model simulations indicate that disks of approximately 1 microm diameter are bent at a degree of photo-activation of 61% to a radius of approximately 0.25 microm, assuming a cylindrical bending modus. The large light-induced bending effect is consistent with light-induced opening of the protein on the cytoplasmic side of the membrane detected by electron crystallography, which is amplified due to coupling of monomers in the membrane. Bending may function as a mechanical signal.     

Social interactions and cortisol treatment increase the production of aggressive electrocommunication signals in male electric fish,Apteronotus leptorhynchus

Brown ghost knife fish, Apteronotus leptorhynchus, continually emit a weakly electric discharge that serves as a communication signal and is sensitive to sex steroids. Males modulate this signal during bouts of aggression by briefly (approximately 15 ms) increasing the discharge frequency in signals termed "chirps." The present study examined the effects of short-term (1-7 days) and long-term (6-35 days) male-male interaction on the continuous electric organ discharge (EOD), chirping behavior, and plasma levels of cortisol and two androgens, 11-ketotestosterone (11KT) and testosterone. Males housed in isolation or in pairs were tested for short-term and long-term changes in their EOD frequency and chirping rate to standardized sinusoidal electrical stimuli. Within 1 week, chirp rate was significantly higher in paired fish than in isolated fish, but EOD frequency was equivalent in these two groups of fish. Plasma cortisol levels were significantly higher in paired fish than in isolated fish, but there was no difference between groups in plasma 11KT levels. Among paired fish, cortisol levels correlated positively with chirp rate. To determine whether elevated cortisol can cause changes in chirping behavior, isolated fish were implanted with cortisol-filled or empty Silastic tubes and tested for short-term and long-term changes in electrocommunication signals and steroid levels. After 2 weeks, fish that received cortisol implants showed higher chirp rates than blank-implanted fish; there were no difference between groups in EOD frequency. Cortisol implants significantly elevated plasma cortisol levels compared to blank implants but had no effect on plasma 11KT levels. These results suggest that male-male interaction increases chirp rate by elevating levels of plasma cortisol, which, in turn, acts to modify neural activity though an 11KT-independent mechanism.     

急性脊髓损伤后大鼠电刺激运动诱发电位的变化

目的：比较不同程度脊髓损伤（SCI）与运动诱发电位（MEP）变化之间的关系,探索MEP检查在SCI早期诊断及预后中的价值。方法：27只雄性SD大鼠以改良Allen‘s打击法致伤T8－T9脊髓,按打击冲量随机分为空白对照组（n=5),SCI A组（50gcf,n=8),SCI B组（70gcf,n=8)和SCI C组（100gcf,n=6),采用单极经皮层电刺激,分别于损伤前、伤后即刻、15min、30min、1h、3h和6h连续观察scMEP变化,并计算脊髓出血坏死区域占脊髓横截面积的比率。结果：对照组MEP无显著改变,SCI A组和SCI B组动物MEP早成份波幅立即减低或消失,以后有所恢复,晚成份波消失后未再出现。SCI C组动物除2只大鼠SCI后MEP仍有所恢复外,其余动物再未出现MEP波。脊髓损伤随打击冲量增大而增加,与伤后1h scMEP最大波幅呈显著相关（r=-0.821)。结论：SCI后scMEP的变化程度与打击冲量和脊髓病理损伤面积相关,提示scMEP可以作为一种脊髓功能检测的客观指标。     

Changes in physico-chemical properties of human large intestine tumour cells membrane

Tumour cells produce and excrete to blood many substances which are present in the cell itself in trace amounts only. Our work has been aimed at the determination of changes in electric charge and in phospholipid composition of large intestine normal mucosa and colorectal cancer cells.Surface charge density of tumour unaffected mucosa and of tissue sections from tumours, was measured by electrophoresis. The measurements were carried out at various pH of solution. Membrane isoelectric point was determined by measuring its electric charge in function of pH as well as total positive charge at low pH and total negative charge at high pH. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC. Four phospholipid classes were identified: PI, PS, PE and PC and their surface concentrations were determined.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized.Tumour changes provoke an increase in surface charge density of large intestine membrane, whereas the content of individual phospholipids increased or decreased depending on a patient.     

The secretory response through electric stimulation of differentiated PC12 rat pheochromocytoma cells transfected with neuropeptide Y fused with enhanced green fluorescent protein

Exocytosis in pheochromocytoma cells was induced by electric stimulation. To chase the movement of vesicles by electric stimulation, dense-core secretory vesicles were visualized by expression of the fusion protein between neuropeptide Y and enhanced green fluorescent protein (EGFP) in these differentiated PC12 rat pheochromocytoma cells. When the cells were stimulated with constant voltage potential at –300 mV, the movement of dense-core secretory vesicles could be regulated.