1,5-diamino-2-pentyne is both a substrate and inactivator of plant copper amine oxidases.

1,5-diamino-2-pentyne (DAPY) was found to be a weak substrate of grass pea (Lathyrus sativus, GPAO) and sainfoin (Onobrychis viciifolia, OVAO) amine oxidases. Prolonged incubations, however, resulted in irreversible inhibition of both enzymes. For GPAO and OVAO, rates of inactivation of 0.1-0.3 min(-1) were determined, the apparent KI values (half-maximal inactivation) were of the order of 10(-5) m. DAPY was found to be a mechanism-based inhibitor of the enzymes because the substrate cadaverine significantly prevented irreversible inhibition. The N1-methyl and N5-methyl analogs of DAPY were tested with GPAO and were weaker inactivators (especially the N5-methyl) than DAPY. Prolonged incubations of GPAO or OVAO with DAPY resulted in the appearance of a yellow-brown chromophore (lambda(max) = 310-325 nm depending on the working buffer). Excitation at 310 nm was associated with emitted fluorescence with a maximum at 445 nm, suggestive of extended conjugation. After dialysis, the color intensity was substantially decreased, indicating the formation of a low molecular mass secondary product of turnover. The compound provided positive reactions with ninhydrin, 2-aminobenzaldehyde and Kovacs' reagents, suggesting the presence of an amino group and a nitrogen-containing heterocyclic structure. The secondary product was separated chromatographically and was found not to irreversibly inhibit GPAO. MS indicated an exact molecular mass (177.14 Da) and molecular formula (C10H15N3). Electrospray ionization- and MALDI-MS/MS analyses yielded fragment mass patterns consistent with the structure of a dihydropyridine derivative of DAPY. Finally, N-(2,3-dihydropyridinyl)-1,5-diamino-2-pentyne was identified by means of 1H- and 13C-NMR experiments. This structure suggests a lysine modification chemistry that could be responsible for the observed inactivation.     

Kinetic studies of electron transfer in the cyt b 5 : metHb system

 The kinetics of methemoglobin reduction by cytochrome b ₅ has been studied by stopped-flow and saturation transfer NMR. A forward rate constant k _f = 2.44×10⁴ M^–1 s^–1 and a reverse rate constant k _b = 540 M^–1s^–1 have been observed at 10 mm, pH 6.20, 25  °C. The ratio k _f/k _b = k _eq = 43.6 is in good agreement with the equilibrium constant calculated from the electrochemical potential between cyt b ₅ and methemoglobin. A bimolecular collisional mechanism is proposed for the electron transfer from cyt b ₅ to methemoglobin based on the kinetic data analysis. The dependence of the rate constants on ionic strengths supports such collisional mechanism. It is also found that the reaction rate strongly depends on the conformations of methemoglobin. Received: 20 February 1996 / Accepted: 4 June 1996     

高压静电场分离水稻、油菜及芝麻种子对萌发期生物效应的影响

落入高压静电场内的水稻、芝麻及油菜种子,在场的作用下,即产生沿电场方向的位移,在同一跌落高度下,重量基本相同的种子,其分离距离产生很大的差异,且分离距离与种子的发芽率及发芽势的改善程度存在着较为明显的相关关系,研究中证实,种子活力强度得到提高,其α淀粉酶活性、蛋白酶活性、脂肪酶活性及电导率得到明显的改善。     

菜蚜二项式抽样设计及其精度分析

１９９０～１９９２年间对杭州市郊区青菜上桃蚜（Ｍｙｚｕｓｐｅｒｓｉｃａｅ）、萝卜蚜（Ｌｉｐａｐｈｉｓｅｒｙｓｉｍｉ）及其混合种群的田间近１００组调查数据,利用每样方（株）虫口不超过数阈值Ｔ（分别为０、１、５、１０、２０、３０、４０）头蚜虫的植株比例（ＰＴ）与种群密度（ｍ,头·株－１）的关系,通过拟合经验公式ｌｎ（ｍ）＝ａ＋ｂｌｎ［－ｌｎ（ＰＴ）］而设计的二项式抽样．通过对三者不同数阈值（Ｔ）的回归决定系数（ｒ２）、种群密度的回归估计方差（Ｖａｒ（ｍ））、抽样精度（以ｄ表示）和实际应用等的比较,结果表明当桃蚜种群处于较高密度即ｍ≥１０时,其理想的Ｔ值为３０;当萝卜蚜种群处于较高密度即ｍ≥５时,其理想的Ｔ值为１０;而它们的混合种群未得到其理想的Ｔ值．数阈值Ｔ为３０和１０可分别用于桃蚜和萝卜蚜的二项式抽样设计．而传统的二项式抽样即０～１抽样由于应用于小白菜上菜蚜的抽样设计时产生很大的误差,不宜采用．     

温度对桃蚜、萝卜蚜体重及种群参数的影响

桃蚜Myrus perslcae、萝卜蚜Lipaphis crystml在能正常产仔的整个恒温范围内,成蚜和新产仔蚜体重随温度的变化都符合二次抛物线,但体重最高值出现较低的温度下．即体重变化主要表现为随温度升高而下降的趋势．在组建蚜虫的生命生殖力表时,以新产仔蚜体重对其在各温度下的生殖事进行校正。并未对计算所得的内禀增长能力rm值及其随温度的变化情况产生明显的影响,不仅没有提供新的信息。相反。这一方法使计算所得rm的值含义模糊。故建议不予采用。     

耐热蛋白质延长因子(EF-Tu)的分子和功能的性质(英文)

本文用亲和层析法从Calderobacteriumhydrogenophilum(极端耐热细菌)中分离得到纯的耐热蛋白质延长因子。测得其相对的分子量为51000。该蛋白质对热极其稳定,从膜过滤分析法测定EF-Tu 的活性可知,在80℃加热5 min后,原活性仅仅失去50%。Ouchterlony双向免疫扩散的结果表明,该蛋白延长因子与E.coli 延长因子有着抗原的相似性。而且该因子只含一个半胱氨酸残基,其位置在半胱氨酸81,即肽段T_(13)。Southern 杂交试验的结果显示出C.hydrogenophilum 的染色体DNA 中可能有两个基因编码同一蛋白。     

库布齐东段不同植被恢复阶段荒漠生态系统碳氮储量及分配格局

为科学评价植被恢复促进沙漠化逆转对碳氮储量的影响,以流动沙地、半固定沙地、油蒿固定沙地、柠条固定沙地、沙柳固定沙地5个阶段荒漠生态系统为研究对象,采用时空替代法分析植被恢复过程中荒漠生态系统碳氮储量及分配格局。结果表明:不同恢复阶段碳氮储量均表现为:流动沙地(3320.97 kg C/hm~2、346.69 kg N/hm~2)半固定沙地(4371.46 kg C/hm~2、435.95 kg N/hm~2)油蒿固定沙地(6096.50 kg C/hm~2、513.76 kg N/hm~2)柠条固定沙地(9556.80 kg C/hm~2、926.31 kg N/hm~2)沙柳固定沙地(19488.54 kg C/hm~2、982.11 kg N/hm~2)。植被层碳氮储量均呈现随植被恢复逐渐增加的趋势,除流动沙地外,其他阶段碳氮储量均以灌木层为主,占比分别为66.65%—91.41%和52.94%—93.39%,草本和凋落物占比较小。灌木各器官生物量及碳储量分配均为:茎根叶,氮储量分配无明显规律,草本各器官生物量及碳氮储量分配均为地上部分高于地下部分。土壤层是荒漠生态系统碳氮储量的主体,碳储量占比为68.64%—99.62%,氮储量占比为89.26%—99.89%,同样呈现随植被恢复逐渐增加的趋势。碳氮储量随土层加深逐渐降低,具有明显的表层富集特征,且随植被恢复过程富集性显著加强。这说明人工建植促进植被演替实现沙漠化逆转可以显著增强荒漠生态系统的碳氮固存能力。     

微生物介导的金纳米颗粒合成

金纳米颗粒凭借其独特的光学和电化学特性,广泛应用于信息存储、化学传感、医学成像、药物传输以及生物标记等领域。近年来,生物法合成金纳米颗粒因其环境友好、绿色低毒等特点引起研究者的广泛关注。研究表明,多种微生物包括细菌、放线菌、真菌和病毒等均具有合成金纳米颗粒的能力。本文综述了微生物介导合成金纳米颗粒的特性、机制及应用,并对未来发展趋势进行了展望。     

Intravital lipid droplet labeling and imaging reveals the phenotypes and functions of individual macrophages in vivo

Macrophages play pivotal roles in the maintenance of tissue homeostasis. However, the reactivation of macrophages toward proinflammatory states correlates with a plethora of inflammatory diseases, including atherosclerosis, obesity, neurodegeneration, and bone marrow (BM) failure syndromes. The lack of methods to reveal macrophage phenotype and function in vivo impedes the translational research of these diseases. Here, we found that proinflammatory macrophages accumulate intracellular lipid droplets (LDs) relative to resting or noninflammatory macrophages both in vitro and in vivo, indicating that LD accumulation serves as a structural biomarker for macrophage phenotyping. To realize the staining and imaging of macrophage LDs in vivo, we developed a fluorescent fatty acid analog-loaded poly(lactic-co-glycolic acid) nanoparticle to label macrophages in mice with high efficiency and specificity. Using these novel nanoparticles, we achieved in situ functional identification of single macrophages in BM, liver, lung, and adipose tissues under conditions of acute or chronic inflammation. Moreover, with this intravital imaging platform, we further realized in vivo phenotyping of individual macrophages in the calvarial BM of mice under systemic inflammation. In conclusion, we established an efficient in vivo LD labeling and imaging system for single macrophage phenotyping, which will aid in the development of diagnostics and therapeutic monitoring. Moreover, this method also provides new avenues for the study of lipid trafficking and dynamics in vivo.Supplementary key words: macrophage, inflammation, lipid droplet, nanoparticle delivery, in vivo imaging, fatty acid analog, bone marrow, systemic inflammation, lipid trafficking, biomarker

Macrophages, a type of immune cells, almost reside in all tissues of body, from the skin to the bone marrow (BM) (1). Macrophages have remarkable plasticity, and they can be activated into specific subtypes by modifying their physiology and functions in response to local environmental cues. Activated macrophages are commonly divided into proinflammatory killing subtype and anti-inflammatory repairing subtype. Proinflammatory macrophages responding to bacteria, IFN-γ, and lipopolysaccharide (LPS) are involved in host defense and inflammation, whereas anti-inflammatory macrophages responding to interleukin-4 (IL-4), IL-10, and IL-13 play a pivotal role in tissue homeostasis and remodeling (2). Increasing evidence indicates that the reactivation of macrophages toward proinflammatory states under diverse kinds of stress is correlated with a plethora of inflammatory diseases, such as atherosclerosis, diabetes, obesity, rheumatoid arthritis, neurodegeneration, and BM failure syndromes (3, 4). Thus, characterization of macrophage activation status and the underlying molecular mechanism in situ will help elucidate their functions in these diseases; however, in vivo analysis of the macrophage activation status in their native multicellular microenvironment is challenging.Although lipid droplets (LDs) have been initially described as intracellular fat storage organelles in adipocytes, increasing studies indicate that myeloid cells also form LDs under inflammation and stress (5, 6). Macrophages, as the effector cells of innate immunity, are found to form LDs to support their host defense when exposed to pathogens, such as parasites, bacteria, and viruses (7, 8, 9, 10, 11). However, abnormal LD accumulation in tissue-resident macrophages correlates with the pathogenesis of various inflammatory diseases. For instance, foam cells in atherosclerotic lesions can maintain the local inflammatory response by secreting proinflammatory cytokines (12, 13, 14). Moreover, LD-accumulating microglia contribute to neurodegeneration by producing high levels of reactive oxygen species (ROS) and secreting proinflammatory cytokines (15). These findings indicate that LD accumulation might be a hallmark of macrophages with proinflammatory functions.In this study, based on the typical activation of in vitro BM-derived macrophages, we find that proinflammatory M_{(LPS + IFN-γ)} macrophages are characterized by LD accumulation, whereas resting macrophages and anti-inflammatory M_(IL-4) and M_(IL-10) macrophages do not contain any LDs. These features also hold for Matrigel plug-recruited macrophages and tissue-resident macrophages in mice. These findings demonstrate that LD accumulation could serve as a morphological index to distinguish proinflammatory macrophages from others.It is feasible to distinguish LD-containing cells using imaging techniques, which has translational potential for identification of proinflammatory macrophages in vivo. However, current techniques for LD visualization are traditional in vitro staining method, and in vivo staining and imaging of LD in individual macrophages remains a challenge. Through nanocarrier screening, we selected the poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) as nanocarrier to deliver the lipophilic carbocyanine dye (DiI_C18(5) solid (1,1''-dioctadecyl-3,3,3'',3''-tetramethylindodicarbocyanine, 4-chlorobenzenesulfonate salt) [DiD]) and lipid staining dye (C1-BODIPY 500/510-C12) into macrophages. Using these dual fluorescence-labeled PLGA NPs, we achieved in situ and in vivo functional identification of single macrophages in various tissues under systemic or local inflammatory stress. Collectively, this study establishes an efficient in vivo labeling and imaging system of intracellular LDs for phenotyping the activation status and functions of individual macrophages in their dynamic niche, which is pivotal for disease diagnosis and preclinical research.