Interactions of a designed peptide with lipopolysaccharide: Bound conformation and anti-endotoxic activity

Designed peptides that would selectively interact with lipopolysaccharide (LPS) or endotoxin and fold into specific conformations could serve as important scaffolds toward the development of antisepsis compounds. Here, we describe solution structure of a designed amphipathic peptide, H₂N-YVKLWRMIKFIR-CONH₂ (YW12D) in complex with endotoxin as determined by transferred nuclear Overhauser effect spectroscopy. The conformation of the isolated peptide is highly flexible, but undergoes a dramatic structural stabilization in the presence of LPS. Structure calculations reveal that the peptide presents two amphipathic surfaces in its bound state to LPS whereby each surface is characterized by two positive charges and a number of aromatic and/or aliphatic residues. ITC data suggests that peptide interacts with two molecules of lipid A. In activity assays, YW12D exhibits neutralization of LPS toxicity with very little hemolysis of red blood cells. Structural and functional properties of YW12D would be applicable in designing low molecular weight non-toxic antisepsis molecules.     

Prefibrillar transthyretin oligomers and cold stored native tetrameric transthyretin are cytotoxic in cell culture

Recent studies suggest that soluble, oligomeric species, which are intermediates in the fibril formation process in amyloid disease, might be the key species in amyloid pathogenesis. Soluble oligomers of human wild type transthyretin (TTR) were produced to elucidate oligomer properties. Employing ThT fluorescence, time-resolved fluorescence anisotropy of pyrene-labeled TTR, chemical cross-linking, and electron microscopy we demonstrated that early formed soluble oligomers (within minutes) from A-state TTR comprised on the average 20-30 TTR monomers. When administered to neuroblastoma cells these early oligomers proved highly cytotoxic and induced apoptosis after 48 h of incubation. More mature fibrils (>24 h of fibrillation) were non-toxic. Surprisingly, we also found that native tetrameric TTR, when purified and stored under cold conditions (4 °C) was highly cytotoxic. The effect could be partially restored by increasing the temperature of the protein. The cytotoxic effects of native tetrameric TTR likely stems from a hitherto unexplored low temperature induced rearrangement of the tetramer conformation that possibly is related to the conformation of misfolded TTR in amyloigogenic oligomers.     

Activation of cardiac progenitor cells through paracrine effects of mesenchymal stem cells

Mesenchymal stem cells (MSC) transplantation has been proved to be promising strategy to treat the failing heart. The effect of MSC transplantation is thought to be mediated mainly in a paracrine manner. Recent reports have suggested that cardiac progenitor cells (CPC) reside in the heart. In this study, we investigated whether MSC had paracrine effects on CPC in vitro. CPC were isolated from the neonatal rat heart using an explant method. MSC were isolated from the adult rat bone marrow. MSC-derived conditioned medium promoted proliferation of CPC and inhibited apoptosis of CPC induced by hypoxia and serum starvation. Chemotaxis chamber assay demonstrated that MSC-derived conditioned medium enhanced migration of CPC. Furthermore, MSC-derived conditioned medium upregulated expression of cardiomyocyte-related genes in CPC such as β-myosin heavy chain (β-MHC) and atrial natriuretic peptide (ANP). In conclusion, MSC-derived conditioned medium had protective effects on CPC and enhanced their migration and differentiation.     

Recovery plan for an exploited species, southern bluefin tuna

Southern bluefin tuna (SBT) were heavily depleted in the mid-1980s, and the fishing quota has been restricted since 1985. As a result of this restriction and protection of immature individuals, spawning stock biomass (SSB) recently has shown a slight increase. The Commission for the Conservation of Southern Bluefin Tuna (CCSBT) has the target of recovering SSB to the 1980 level by 2020. We investigated whether SBT populations will recover and reach the target level set by CCSBT. Our projection shows that the SSB of the SBT will temporarily decrease again after 1999. This temporary decrease of SSB does not always mean failure of the recovery plan, because the SSB trend is highly vulnerable to age-composition dynamics. The SBT is an example of this. The number of mature SBT was small during the 1980s because of overfishing. Thus, the number of eggs that were spawned by these mature SBT was small in these years, and when these small numbers of immature fish become mature, the SSB will decrease again. We call this effect the inverse baby-boom effect. The inverse baby-boom effect may be common for managed bioresources that have once been overexploited. We also examine the use of spawning potential (SP) and SSB as an index of stock recovery. Received: August 17, 2000 / Accepted: March 19, 2001     

树木气孔浸润级与SO2伤害及ABA的防护作用

以常见绿化树种为材料,通过实地测定和熏烟实验,探讨了气孔浸润级与树木SO₂伤害的关系及ABA的防护效应.结果表明,在特定环境下,相同树种的气孔浸润级较为稳定,不同树种的气孔浸润级差异较大;浸润级与叶绿素结合度呈负相关变化,但不明显;与K⁺渗出量呈正相关(r=0.92,α＜0.01),并按95%的置信度绘制了伤害预测图.不同SO₂浓度条件下,对同一树种的气孔浸润级的影响甚小,不超过一个等级,K⁺渗出量则依大气SO₂浓度和树木吸S量的增加而增多.气孔浸润级依ABA溶液处理浓度增大而降低,K⁺渗出量也相应减少,经2.5mol·L^-1×4h剂量的SO₂熏烟,预涂30mol·L^-1ABA者,降低了1.5～3个浸润级,K⁺渗出量减少36.5%～54.8%,其测定值与自然对照值相近,防护作用显著.     

树木气孔浸润级与SO_2伤害及ABA的防护作用

以常见绿化树种为材料 ,通过实地测定和熏烟实验 ,探讨了气孔浸润级与树木SO2 伤害的关系及ABA的防护效应 .结果表明 ,在特定环境下 ,相同树种的气孔浸润级较为稳定 ,不同树种的气孔浸润级差异较大 ;浸润级与叶绿素结合度呈负相关变化 ,但不明显 ;与K 渗出量呈正相关 (r =0 .92 ,α <0 .0 1) ,并按 95 %的置信度绘制了伤害预测图 .不同SO2 浓度条件下 ,对同一树种的气孔浸润级的影响甚小 ,不超过一个等级 ,K 渗出量则依大气SO2 浓度和树木吸S量的增加而增多 .气孔浸润级依ABA溶液处理浓度增大而降低 ,K 渗出量也相应减少 ,经 2 .5mol·L-1× 4h剂量的SO2 熏烟 ,预涂 30mol·L-1ABA者 ,降低了 1.5～ 3个浸润级 ,K 渗出量减少 36 .5 %～ 5 4.8% ,其测定值与自然对照值相近 ,防护作用显著 .     

长安麦饭石在月季切花上的保鲜效果

在40g/L蔗糖＋50mg/L SA 100mg/L Vc的保鲜液中,加入37μS/cm的长安麦饭石（CHMS）,能更好的保持月季切花较高的吸水能力,增强切花花朵膜损伤修复能力,增大花朵开放直径,增加盛开前花枝的鲜重,提高切花瓶插期的观赏品质,延长瓶插寿命。本试验也证明了水杨酸（SA）与8－羟基喹啉（8－HQ）对月季切花有相似的保鲜效果。     

新疆紫草中抗生育化学成分

从新疆紫草(Arnebia euchroma(Royle)Johnst.)的根部分得四种酚类化合物,经波谱分析,确定为rabdosiin二钾盐(dipotassium rabdosiin 1),迷迭香酸钾盐(potassium rosmarinate 2),迷迭香酸钠盐(sodium rosmarinate 3),阿魏酸钠盐(sodium ferulate 4).其中rabdosiin二钾盐具有显著的抗生育活性,而迷迭香酸钾盐、迷迭香酸钠盐和阿魏酸钠盐为首次从该植物中分离获得.     

Effects of rhizome age on the decomposition rate of Phragmites australis rhizomes

The change in dried rhizome samples that were left to decompose was investigated to elucidate the effects of rhizome age on the decomposition rate of Phragmites australis. Rhizomes were classified into five age categories and placed 30 cm below the soil surface of a reed stand. After 369 days of decay, new (i.e., aged less than one year) rhizomes had lost 84% of their original dry mass, compared with a loss of 41–62% for that of older rhizomes. The exponential decay rates of older rhizomes were nearly identical to that of aboveground biomass. The nitrogen (N) concentration increased to two times its original values, but the phosphorus (P) concentration remained constant after an initial loss by leaching. The carbon to nitrogen (C:N) and carbon to phosphorus ratios (C:P) leveled out at 22:1 to 38:1 and 828:1 to 1431:1, respectively, regardless of rhizome age. The results are important to understand the nutrient cycles of reed-dominant marsh ecosystems.