Interactions of 14N:15N stearic acid spin-label pairs: effects of host lipid alkyl chain length and unsaturation

Electron-electron double resonance (ELDOR) and saturation recovery electron paramagnetic resonance (EPR) spectroscopy have been employed to examine the interactions of 14N:15N stearic acid spin-label pairs in fluid-phase model membrane bilayers composed of a variety of phospholipids. The [14N]-16-doxylstearate:[15N]-16-doxylstearate (16:16) pair was utilized to measure lateral diffusion of the spin-labels, while the [14N]-16-doxylstearate:[15N]-5-doxylstearate (16:5) pair provided information on vertical fluctuations of the 16-doxylstearate nitroxide moiety toward the membrane surface. Three saturated host lipids of varying alkyl chain length [dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), and distearoylphosphatidylcholine (DSPC)], an alpha-saturated, beta-unsaturated lipid [1-palmitoyl-2-oleoylphosphatidylcholine (POPC)], and phosphatidylcholine from a natural source [egg yolk phosphatidylcholine (egg PC)] were utilized as host lipids. Lateral diffusion of the stearic acid spin-labels was only slightly affected by alkyl chain length at a given reduced temperature (Tr) in the saturated host lipids but was significantly decreased in POPC at the same Tr. Lateral diffusion in DMPC, POPC, and egg PC was quite similar at 37 degrees C. A strong correlation was noted between lateral diffusion constants and rotational mobility of [14N]-16-doxylstearate. Vertical fluctuations were likewise only slightly influenced by alkyl chain length but were strongly diminished in POPC and egg PC relative to the saturated systems. This diminution of the 16:5 interaction was observed even under conditions where no differences were discernible by conventional EPR. These studies indicate that vertical fluctuation of 16-doxylstearate is quite sensitive to host lipid unsaturation and that ELDOR studies of interactions between 14N:15N spin-label pairs can provide information on spin-label motion beyond that given by conventional EPR.     

Lectin bindings and diethylstilbestrol effects on the recognition of mullerian inhibiting substance (MIS) on chick mullerian ducts by MIS-antiserum

Summary A high intensity of lectin bindings was demonstrated on the epithelial cells and serosa cells of the regressing right Mullerian ducts (Mds) in the female chick embryos. The strong lectin bindings occurs on, or in the regressing Md cells along with marked surface MIS bindings at the age of day 13. However, at the age of days 5–7 1/2, bindings of lectins were weak. Neither Wheat-germ agglutinin (WGA) or Concanavalin A (Con-A) labelings before MIS-antiserum (MIS-Ab) incubation can block antibody recognitions to the antigens, including MIS and growth hormone at the age of day 13. Our previous studies indicated that after WGA labeling on the surfaces of Md epithelial cells prior to the incubation of MIS-Ab at day 10 did not prevent the recognition of MIS-Ab (Wang 1989). On the contrary, at day 7 1/2, the specific binding of MIS was eliminated after preincubations with lectins and prenatal diethylstilbestrol (DES) treatment at the age of day 5. It is suggested that DES provides a protection to the Mds from MIS-induced regression by preventing the MIS binding to its specific membrane receptors. An increase of extra- and intracellular glycoproteins or carbohydrates of regressing Md epithelial cells were suggested. Internalization of WGA but not MIS molecules was found in Md epithelial cells. The Golgi saccules were negative of lectin bindings.     

九江地区人头发横断面的研究

本文对九江市汉族463例健康人,4710根头发横断面进行观察和显微测量。分析了本地区人年龄与头发直径的关系、年龄与头发黑色素颗粒分布的关系。结果表明:黑色素颗粒随年龄增长而渐浓密,成年人最丰富,老年人头发黑色素颗粒则渐崩溃稀少;头发各径亦随年龄增长而增大,而老年人头发各径是逐渐减小。此外,本文还同欧、亚、美国各民族人头发资料进行比较。根据头发指数,确定本市人头发形伏为直发形。     

鹅掌楸种子和胚胎发育的研究

应用控制授粉、软 X-射线法、常规石蜡制片法和荧光检测等手段,研究了鹅掌楸(Lirio-dendron chinense(Hemsl.)Sarg.胚胎发育和控制授粉与结籽率的相关性。控制授粉后2小时花粉萌发,6小时萌发率最高,柱头可授期持续30小时左右。花粉管借助于柱头毛之间的分泌物进入柱头沟,经花柱沟、珠孔塞和珠心冠原进入胚囊,行珠孔受精。授粉后2周,胚乳为2至3细胞厚的狭组织;第6周,胚乳充满胚囊腔,珠心随之解体殆尽;第7到8周,球形胚、心形胚发生;第14到16周,子叶形成;第22周种子或熟,胚乳丰富。单株自然授粉结籽率不足1%。控制授粉后,单个聚合果的最高结籽率可达39%,9个聚合果的平均结籽率为17.7%。     

An endemic brackish water faunule from the middle jurassic of southern qinghai province,China

An endemic brackish water faunule consisting of three taxa of bivalves,Hudsonella sinensis (Chen) n. gen.,Hudsonella sp., andProtocardia hepingxiangensis Chen & Lin occurs in the Bajocian of the southern Qinghai province, China.Hudsonella sinensis is a very variable species with a hinge structure characteristic of the subfamily Pachydontinae of the family Corbulidae. According to both geochemical data (stable carbon isotopes and the strontium/barium ratio) and ecological data the faunule lived in a brackish water embayment of mesohaline salinity (5#x2013;18 per mil) burrowing in soft substrate.     

Characterization of a human cervical carcinoma-associated antigen by lectin binding and immuno-electron microscopy

Summary The specific binding and nature of the epitope recognized by monoclonal antibody (Mab) 1H10, which binds an antigen expressed on human cervical tumors, was characterized by enzyme digestion, lectin competition assay and immuno-electron microscopy. Membrane homogenates of CaSki cervical carcinoma cells were digested with various enzymes, then analysed by SDS-PAGE and immunoblotting. Cells grown on coverslips were treated with various enzymes and in situ binding of Mab 1H10 to cells was analysed by electron microscopy. The ability of lectin-conjugates to block Mab 1H10 binding to CaSki cells was also examined. Treatment of samples with sodium periodate abrogated antigen recognition by Mab 1H10. Neuraminidase and hyaluronidase digestion decreased but did not eliminate Mab 1H10 binding to cells in situ. Chondroitinase ABC digestion, in contrast, removed Mab 1H10 binding sites both in vitro and in situ. Trypsin and chymotrypsin digestion of cell membrane homogenates decreased the molecular weight of the Mab 1H10 antigen but did not decrease the binding intensity. Wheat germ agglutinin (WGA) strongly bound to CaSki cells and partially blocked Mab 1H10 binding, indicating that the antigen contains N-acetyl-galactosamine residues at or near the epitope recognized by Mab 1H10. Ricinus communis agglutinin (RCA) exhibited a similar binding pattern to WGA. However, concanavalin A bound only weakly to CaSki cells and was ineffective at blocking Mab 1H10 binding. The tumor-associated antigen recognized by Mab 1H10 is concluded to be a chondroitin sulphate glycoprotein or proteoglycan rather than a mucopolysaccharide or lipoprotein.     

点状气单胞菌引起虹鳟感染症及其病原学机制的初步研究

对山西省朔县省虹鳟试验场1987年8月在亲鱼中爆发的一次流行病进行了病原菌分离、培养、毒力试验和详细的生理生化测定,确定点状气单胞菌为其病原菌。并对该菌胞外产物的致病性进行了研究,通过测定其溶血活性、酪蛋白酶活性、对鱼致死性以及对其引起的组织病理学变化的观察,初步确定了胞外产物与该菌侵袭力的相关性。     

高原低氧对机体无氧代谢阈值的影响

为了探讨高原低氧对机体无氧代谢阈值(AT)的影响,本研究采用Wasserman无创性方法,分别测定了11名新兵在平原(四川淮口,海拔500m)和经空运进驻高原 (西藏错那,海拔4370m)后的第3、5、7和14天的AT。结果表明:新兵进驻高原后AT由平原的813.6±147.4kg·m/min降低到395.5±194.5 kg·m/min(P<0.01);高原低氧引起AT的降低幅度与受试者平原AT的高低呈正相关(r=0.933,P<0.01);进驻高原后第3、5、7天AT维持在较低水平,随后呈上升趋势。但移居高原1年战士的AT仍低于平原水平(P<0.05)。提示,高原低氧能够显著地降低机体的AT,并且AT越高的个体进驻高原后受低氧环境的影响程度越大。