An imaging system for standardized quantitative analysis of <Emphasis Type="Italic">C. elegans</Emphasis> behavior

Background  

The nematode Caenorhabditis elegans is widely used for the genetic analysis of neuronal cell biology, development, and behavior. Because traditional methods for evaluating behavioral phenotypes are qualitative and imprecise, there is a need for tools that allow quantitation and standardization of C. elegans behavioral assays.     

Copper complex of hydroxyl-substituted triazamacrocyclic ligand and its antitumor activity

The protonation constants and the stability constants for the formation of copper (II) complex of the ligand [1,4,7] Triazecan-9-ol (L) were presented. Antitumor activity of CuL complex was reported. Preliminary pharmacological tests showed that it had antitumor activity against HXO-RB44 and BEL-7402 cell lines in vitro. Nuclei of [CuL]-stimulated BEL-7402 cells clearly exhibited condensation and break down into chromatin clumps typical of apoptosis. Also it exhibited perturbation effects to BEL-7402 cell lines cycle and further studies showed that it could cleave supercoiled DNA (pBR 322) to nicked and linear DNA.     

Low-density lipoprotein receptor family: endocytosis and signal transduction

The low-density lipoprotein receptor (LDLR) family is composed of a class of single transmembrane glycoproteins, generally recognized as cell surface endocytic receptors, which bind and internalize extracellular ligands for degradation by lysosomes. Structurally, members of the LDLR family share homology within their extracellular domains, which are highlighted by the presence of clusters of ligand-binding repeats. Recently, information regarding the structural and functional elements within their cytoplasmic tails has begun to emerge, which suggests that members of the LDLR family function not only in receptor-mediated endocytosis, but also in transducing signals that are important during embryonic development and the pathogenesis of Alzheimer's disease. This review focuses on recent knowledge of the structural and functional aspects of LDLR family members in endocytosis and signal transduction. The relationship of these functions to the development of the neuronal system and in the pathogenesis of Alzheimer's disease is specifically discussed.     

Metallohistins: a new class of plant metal-binding proteins

Two small multimeric histidine-rich proteins, AgNt84 and Ag164, encoded by two nodule-specific cDNAs isolated from nodule cDNA libraries of the actinorhizal host plant Alnus glutinosa, represent a new class of plant metal binding proteins. This paper reports the characterization of the purified in vitro-expressed proteins by size exclusion chromatography, circular dichroism, equilibrium dialysis, metal affinity chromatography coupled with mass spectrometry, and nuclear magnetic resonance spectroscopy. These analyses reveal that each polypeptide is capable of binding multiple atoms of Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺, Cd²⁺ and Hg²⁺. A reversible shift in histidine C1 and C2 protons in NMR analysis occurred during titration of this protein with ZnCl₂ strongly suggesting that histidine residues are responsible for metal binding. AgNt84 and Ag164 are not related to metal binding metallothioneins and phytochelatins and represent a new class of plant metal binding proteins that we propose to call metallohistins. Possible biological roles in symbioses for AgNt84 and Ag164, and their potential for use in bioremediation are discussed.     

Changes of adrenomedullin and receptor activity modifying protein 2 (RAMP2) in myocardium and aorta in rats with isoproterenol-induced myocardial ischemia

Adrenomedullin is a potent vasodilator peptide originally isolated from a pheochromocytoma. Recently, a novel adrenomedullin receptor has been identified as a complex of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 2 (RAMP2). To explore the pathophysiological roles of adrenomedullin and its receptor component RAMP2 in ischemic cardiovascular diseases, we studied the changes of adrenomedullin and RAMP2 mRNA in myocardium and aorta in rats with isoproterenol (ISO)-induced myocardial impairment. In ISO-treated rats, heart became enlarged markedly, the ratio of heart to body weight was increased by 54% (P<0.01), and myocardial malondialdehyde content and plasma lactate dehydrogenase activity was elevated by 43% (P<0.01) and 138% (P<0.01), respectively. Immunoreactive adrenomedullin (ADM) in plasma, myocardium and aorta was augmented by 116.7% (P<0.01), 50.8% (P<0.01) and 12.5% (P>0.05), respectively. ADM mRNA in myocardium and aorta was increased by 96.8% (P<0.01) and 38.5% (P<0.01), respectively. RAMP2 mRNA in myocardium and aorta was increased by 19.6% (P<0.05) and 15.8% (P<0.01), respectively. These results suggest that the increase of ADM level and the up-regulation of ADM and RAMP2 gene in myocardium and aorta may be significant in the pathogenesis of ischemic myocardiopathy.     

The C-terminal domain of nucleolin accelerates nucleic acid annealing

We report that the abundant nucleolar protein nucleolin accelerates nucleic acid annealing. Nucleolin accelerates annealing of complementary oligonucleotides and of oligonucleotides that contain a limited number of mismatches. The annealing activity of nucleolin can be localized to a C-terminal region consisting of two RNA binding domains (RBD3 and RBD4) and the RGG(9) domain (RBD3-RBD4-RGG(9)). This same region mediates self-association of nucleolin. The RGG(9) domain of nucleolin, believed to mediate interactions between nucleolin and several ribosomal proteins, is neither sufficient for self-association, as determined by small-angle X-ray scattering, nor can it independently accelerate annealing. Acceleration of nucleic acid annealing by nucleolin is likely to depend on self-association of nucleolin molecules bound to nucleic acid.     

Detection of Escherichia coli O157:H7 in the Beef Marketed in Malaysia

Twelve strains of Escherichia coli O157:H7 were isolated from 9 of 25 beef samples purchased from retail stores in Malaysia. These strains produced Shiga toxin 2 with or without Shiga toxin 1 and had the eae gene and a 60-MDa plasmid. The antibiograms and the profiles of the arbitrarily primed PCR of the strains were diverse, suggesting that the strains may have originated from diverse sources.     

聚合牛血红蛋白抗原性的初步研究

对乙醇醛聚合的牛血红蛋白的抗原性进行了研究。将聚合的牛血红蛋白桉兔血量的10％和20％分别输入兔耳缘静脉,间隔7天后重复输液,共输注3次。ELISA检测未显示抗体产生。将聚合的牛血红蛋白、人血红蛋白和兔血红蛋白分别与免疫佐剂混合常规免疫家兔3次,并用上述抗原包被聚乙烯板,用ELISA方法检测抗体滴度,结果显示聚合牛血红蛋白和人血红蛋白加佐剂免疫家兔后均产生抗体,且有交叉反应,表明这两种血红蛋白有同源性,存在相似的抗厚决定簇。兔血红蛋白免疫家兔后无抗体产生,且无交叉反应,表明机体对自体蛋白有天然的耐受。     

线虫与果蝇先天免疫系统的比较

一般认为无脊椎动物没有获得性免疫系统,先天免疫系统就成了无脊椎动物唯一的防御手段。由于不同物种的生活环境不同,它们所面临的病原体也不同,这就产生了不同物种先天免疫的特异性。主要就线虫和果蝇这2种模式生物在先天免疫系统方面的差异作一比较。