Reconstituted low density lipoprotein: A vehicle for the delivery of hydrophobic fluorescent probes to cells

Previous studies have shown that the cholesteryl ester core of plasma low density lipoprotein (LDL) can be extracted with heptane and replaced with a variety of hydrophobic molecules. In the present report we use this reconstitution technique to incorporate two fluorescent probes, 3-pyrenemethyl-23, 24-dinor-5-cholen-22-oate-3β-yl oleate (PMCA oleate) and dioleyl fluorescein, into heptane-extracted LDL. Both fluorescent lipoprotein preparations were shown to be useful probes for visualizing the receptor-mediated endocytosis of LDL in cultured human fibroblasts. When normal fibroblasts were incubated at 37°C with either of the fluorescent LDL preparations, fluorescent granules accumulated in the perinuclear region of the cell. In contrast, fibroblasts from patients with the homozygous form of familial hypercholesterolemia (FH) that lack functional LDL receptors did not accumulate visible fluorescent granules when incubated with the fluorescent reconstituted LDL. A fluorescence-activated cell sorter was used to quantify the fluorescence intensity of individual cells that had been incubated with LDL reconstituted with dioleyl fluorescein. With this technique a population of normal fibroblasts could be distinguished from a population of FH fibroblasts. The current studies demonstrate the feasibility of using fluorescent reconstituted LDL in conjunction with the cell sorter to isolate mutant cells lacking functional LDL receptors.     

The influence of insulin on glucose permeability and metabolism of human granulocytes.

Viable human polymorphonuclear leukocytes isolated from peripheral blood were incubated for 1 h at 37 degrees C with variable concentrations of insulin in a saline medium buffered at pH 7.4. The hormone increased glucose consumption by about 40% without influencing the permeability of the membranes to glucose, whose uptake followed a passive diffusion process. The measurement of intermediates localized activation of glycolysis by insulin, down to 0.36 nM, at the phosphofructokinase step. However, the spectrophotometric measurement showed no activation of phosphofructokinase after preincubation with insulin of either intact granulocytes or crude or ultracentrifuged homogenates. The level of cyclic AMP, which is known to activate phosphofructokinase, was not modified by insulin; cyclic GMP did not activate the enzyme in the granulocyte extracts: neither of the two nucleotides can therefore be considered as a direct messenger of the action of insulin on phosphofructokinase. An important fraction of the extra glucose consumed under the influence of insulin was recovered as neither glycogen nor lactate, nor was it oxidized in the Krebs cycle. It might be assumed to have been converted into glycerolipids. However, insulin produced no detectable accumulation of triglycerides and activated neither the pentose phosphate pathway nor oxidative decarboxylation of pyruvate. The fate of the extra glucose consumed under the influence of insulin therefore remains questionable.     

Malocclusion of the premolar and molar teeth in the guinea pig.

Malocclusions of the premolar and molar teeth of inbred Strain 2/N and Strain 13/N and outbred Dunkin-Harley guinea pigs were examined. A higher incidence of malocclusion observed in the inbred strains suggested a genetic basis for the disorder.     

河口盐沼植物对大型底栖动物群落的影响

通过对长江口崇明东滩盐沼海三棱燕草带大型底栖无脊椎动物进行取样调查,研究了不同盐沼底栖动物群落结构及其多样性特征,分析了盐沼植物群落特征与底栖动物群落的关系。研究发现。（1）沿着河口盐沼海拔梯度,从低位盐沼到高位盐沼,底栖动物群落结构及多样性具有明显的梯度变化;（2）盐沼植被与底栖动物群落有密切的关系,尤其是植株高度,地下部分生物量与底栖动物密度,Shannon-Weiner多样性指数,物种丰度的相关性最显著。（3）盐沼植被影响底栖动物群落,是由于植物的地下部分和地下部分结构导致盐沼生境结构复杂,增加了沉积物表层环境的结构异质性,使生境多样化,给底栖动物提供大量生活空间,（4）不同盐沼带海三陵蔗草群落的差异,提供了盐沼表层地貌的变化,这种变化及植物结构的复杂化,在这一些动物提供拓殖地的同时,也为底栖动物躲避捕食者提供了避护所;（5）盐沼植被可以改变口潮滩生境中的沉积环境,并通过消浪、缓流及调节有机质的输入动态和沉积作用而影响底栖动物群落的组成和结构。     

A secreted ribonuclease effector from Verticillium dahliae localizes in the plant nucleus to modulate host immunity

The arms race between fungal pathogens and plant hosts involves recognition of fungal effectors to induce host immunity. Although various fungal effectors have been identified, the effector functions of ribonucleases are largely unknown. Herein, we identified a ribonuclease secreted by Verticillium dahliae (VdRTX1) that translocates into the plant nucleus to modulate immunity. The activity of VdRTX1 causes hypersensitive response (HR)‐related cell death in Nicotiana benthamiana and cotton. VdRTX1 possesses a signal peptide but is unlikely to be an apoplastic effector because its nuclear localization in the plant is necessary for cell death induction. Knockout of VdRTX1 significantly enhanced V. dahliae virulence on tobacco while V. dahliae employs the known suppressor VdCBM1 to escape the immunity induced by VdRTX1. VdRTX1 homologs are widely distributed in fungi but transient expression of 24 homologs from other fungi did not yield cell death induction, suggesting that this function is specific to the VdRTX1 in V. dahliae. Expression of site‐directed mutants of VdRTX1 in N. benthamiana leaves revealed conserved ligand‐binding sites that are important for VdRTX1 function in inducing cell death. Thus, VdRTX1 functions as a unique HR‐inducing effector in V. dahliae that contributes to the activation of plant immunity.     

辽东栎林下和开阔地上短柄五加(Acanthopanax brachpus)无性系种群生长的比较研究

研究了分布于开阔地和辽东栎林下短柄五加无性系种群拆散方式、无性系的形态可塑性和分株的死亡年龄,研究结果表明,开阔地上无性系分株的扩散方式为稀疏线型,根茎长度、无性系分株数目,林下和开阔地差异显著,根茎分枝角度、无性系根茎总长无显著性差异。林下分株的死亡年龄显著小于开阔地上无性系分株的死亡年龄。     

长山群岛海域真核微藻粒级结构及扇贝摄食选择性

采用高通量测序-分子鉴定分级技术于2019年对长山群岛全海域真核微藻粒级结构进行了研究。结果发现,春季以中（47%）、小粒级（41%）为主,夏季以小（39%）、大粒级（38%）为主,秋季以大粒级（60%）为主,春、夏、秋季小、中、大粒级微藻比例为42：47：11、39：23：38、22：18：60。小粒级微藻优势种为细小微胞藻（Micromonas pusilla）、融合微胞藻（Micromonas commoda）和金牛微球藻（Ostreococcus tauri）,中粒级微藻优势种为剧毒卡尔藻（Karlodinium veneficum）、大粒级微藻优势种为柔弱几内亚藻（Guinardia delicatula）、平野亚历山大藻（Alexandrium hiranoi）、多纹膝沟藻（Gonyaulax polygramma）,综合整个真核微藻群落,春季由中粒径的剧毒卡尔藻占据优势（23.9%）,夏季由大粒径的平野亚历山大藻占据优势（29.4%）,秋季由大粒径的多纹膝沟藻占据优势（66.8%）,有毒甲藻在该海域中占有绝对优势,贝毒累积风险较高,小粒径微藻中金牛微球藻和抑食金球藻曾在渤海引发褐潮,潜在威胁该海域贝类养殖业。虾夷扇贝对小粒级和大粒级微藻的选择性较低,对中粒级微藻的选择性较高,尤其对水体中优势种剧毒卡尔藻一直表现出主动选择。光学需氧量、无机氮、溶解氧、石油类及部分重金属Cd、As、Hg影响着整个长山群岛海域真核微藻粒级结构时空演变。     

广竹的生物学特性及栽培技术研究

对广竹的生物学特性及栽培技术研究结果表明:广竹的出笋历期较短且非常集中,出笋高峰期集中在4月上旬,出笋数量占全期出笋总数的62.7%;幼竹高生长及枝条生长曲线均呈"S"形,遵循慢—快—慢的节律;此竹种属于混生竹,可移竹繁殖和埋鞭繁殖,前一方法的繁殖效果较好,成活率可达60%,而埋鞭繁殖效果相对较差,成活率只有38%,最佳繁殖时间宜在12月下旬至次年2月进行;根据其各生长阶段的生长规律、无性繁殖栽培技术以及生产实践,提出了主要栽培技术措施。