土壤中含EB病毒诱导物的检测

从广西壮族自治区梧州市、苍梧县、罗城县和北京市收集的土壤标本中发现有EB病毒诱导物。梧州市和苍梧县沿公路和江河两旁桐油树下的土壤标本,对EB病毒早期抗原诱导的阳性率为40～58％。在其他大戟科植物下的土壤标本中,也发现有EB病毒诱导物。对桐油树下土壤中EB病毒诱导物与鼻咽癌发生的可能关系进行了讨论。     

抗胃癌细胞系单克隆抗体PD4的初步研究

以胃癌细胞系MGC803免疫Balb/c小鼠,取其脾细胞与小鼠骨髓瘤细胞NS-1融合。经选择培养、筛选及克隆化,获得恒定地分泌抗胃癌细胞系单克隆抗体(MoAb)的杂交瘤细胞系PD4。MoAb PD4与3/4胃癌细胞系有强结合反应,与4/4肺癌细胞系有弱结合反应,但与淋巴细胞、ABO红细胞、骨髓细胞、二倍体成纤维细胞及经检测的其他肿瘤细胞均无反应。PD4抗原主要表达于靶细胞的膜上,不耐热,为分子量40kD的蛋白性抗原。该抗原与HLA抗原系统,血型抗原系统无关,亦不同于其他作者所报告的其他胃癌相关抗原。     

Electron microscopy and hydrodynamic properties of blood clotting factor V and activation fragments of factor V with phospholipid vesicles

The electron microscopic and hydrodynamic properties of factor V and factor Va-vesicle complexes were determined. Images of negatively stained factor V bound to vesicles showed the protein as a relatively large globular domain (9.5 nm diameter) connected to the membrane through a narrow protein region 0.5-3 nm in length. This connecting region was not always visible and was measured as the distance between the globular region and the apparent vesicle edge. Factor V protein alone usually appeared as two connected globular regions of 10.2 and 6.5 nm diameter. The two-domain protein structure appeared consistent with both the image of factor V alone and bound to the membrane. Factor V had no biological activity in a phospholipid-free prothrombinase assay system used. The proteolytically activated form of factor V generated by digestion with thrombin (factor Va) was at least 30,000 times more active. The electron microscopic images of factor Va-vesicle complexes showed a smaller protein that was more closely associated with the vesicle surface than was factor V. The light chain (Mr about 80,000) component of factor Va also bound to the surface of the vesicles and appeared to be largely external to the membrane. Protein-induced hydrodynamic radius changes for the factor V-vesicle and factor Va-vesicle complexes were 12.8 and 6.3 nm, respectively. The images observed in the electron microscope were used to calculate protein-induced radius changes. Comparison of these values with the experimentally determined hydrodynamic radius changes showed approximate agreement for factor Va-membrane complexes. However, the images of factor V-vesicle complexes suggested smaller hydrodynamic radius changes than were actually observed.     

水分胁迫下露花光合型的转变

CAM植物按其对环境的反应可分为两种类型:即专一CAM植物和兼性CAM植物。前者不易受外界环境的变化而改变其CAM性质;后者的光合型可随季节和水分胁迫等而发生变化,也可因人工诱导作用而使其由C_3型转变为CAM型。     

牛胰多肽对急性胰腺炎大鼠胰组织中磷脂酶A和胰蛋白酶活性的影响

以0.25％牛磺胆酸钠-0.25％胰蛋白酶溶液注入大鼠胰导管制备急性(出血坏死性)胰腺炎模型。观察剂量为 3μg/kg的牛胰多肽(BPP)对胰腺炎大鼠胰组织磷脂酶 A(PA)活性、钙含量、胰蛋白酶活性以及血清α_1-抗胰蛋白酶抑制力(STIC)的影响。结果如下:1.在伴注BPP的胰腺炎组,PA 活性、钙含量、胰蛋白酶活性及STIC 分别降为胰腺炎组的51％(P<0.001),75％(P<0.001)、20％(P<0.001)以及24％(P<0.001);2.在伴注碳酰胆碱的胰腺炎组,上述四项指标的水平升高。但在伴注碳酰胆碱及BPP 两者的胰腺炎组却分别降至伴注碳酰胆碱的胰腺炎组的39％(P<0.005)、51％(P<0.001)、40％(P<0.001)以及 59％(P<0.001);3.在伴注Ca~(2 )的胰腺炎组,上述四项指标剧升,注射 BPP对其无影响。结果提示,BPP 能降低大鼠胰组织内磷脂酶A 和胰蛋白酶活性及胰内钙沉积量。机制可能与 BPP打断胰酶活化链有关,是否还影响腺泡细胞膜上M受体的功能,有待探讨。     

大劣按蚊吸血活动与交配受精的关系

大劣按蚊Anophelos dirus是我国及东南亚地区的重要传疟媒介。研究表明成蚊羽化后,在未喂血的情况下,可有较高的交配受精率。在同一蚊笼,吸血机会完全相同的条件下,大蚊笼受精雌蚊吸血率为59.88%,未受精雌蚊的吸血率为35.38%;小蚊笼受精雌蚊的吸血率为74.13%,未受精雌蚊吸血率仅为43.56%。正常交配雌蚊的吸血率为49.71%,未进行交配的处女雌蚊吸血率为28.42%。同为正常交配蚊群,喂血组雌蚊受精率55.85%,不喂血组的受精率为44.51%。初步认为大劣按蚊的吸血活动与交配受精有一定的关系。     

Electron nuclear double resonance and electron paramagnetic resonance study on the structure of the NO-ligated heme alpha 3 in cytochrome c oxidase

The techniques of EPR and electron nuclear double resonance (ENDOR) were used to probe structure and electronic distribution at the nitric oxide (NO)-ligated heme alpha 3 in the nitrosylferrocytochrome alpha 3 moiety of fully reduced cytochrome c oxidase. Hyperfine and quadrupole couplings to NO (in both 15NO and 14NO forms), to histidine nitrogens, and to protons near the heme site were obtained. Parallel studies were also performed on NO-ligated myoglobin and model NO-heme-imidazole systems. The major findings and interpretations on nitrosylferrocytochrome alpha 3 were: 1) compared to other NO-heme-imidazole systems, the nitrosylferrocytochrome alpha3 gave better resolution of EPR and ENDOR signals; 2) at the maximal g value (gx = 2.09), particularly well resolved NO nitrogen hyperfine and quadrupole couplings and mesoproton hyperfine couplings were seen. These hyperfine and quadrupole couplings gave information on the electronic distribution on the NO, on the orientation of the g tensor with respect to the heme, and possibly on the orientation of the FeNO plane; 3) a combination of experimental EPR-ENDOR results and EPR spectral simulations evidenced a rotation of the NO hyperfine tensor with respect to the electronic g tensor; this implied a bent Fe-NO bond; 4) ENDOR showed a unique proton not seen in the other NO heme systems studied. The magnitude of this proton's hyperfine coupling was consistent with this proton being part of a nearby protein side chain that perturbs an axial ligand like NO or O2.     

Quantum theory of nerve excitation

Based on quantum transitions of membrane dipoles, the four fundamental properties of nerve impulse are derived in this paper: the all-or-none response, the strength-duration relation, refractoriness and refractory period and frequency modulation. Furthermore, the theory offers a physical mechanism for nerve excitation similar to a two-level ammonia maser. It also implies non-threshold excitation at elevated temperatures. The role of trimethylamine ions near the surface of a phospholipid membrane is briefly discussed to indicate a possible connection between theory and reality.     

Carbon Balance of a Mannitol Fermentation and the Biosynthetic Pathway

The carbon balance was determined for a fermentation in which mannitol is produced from glucose by an Aspergillus species. The products found were: cells (17% of carbon input), CO(2) (26%), mannitol (35%), glycerol (10%), erythritol (2.5%), glycogen (1%), and unidentified compounds (8%). Thus, 92% of the carbon input was accounted for. Cell-free enzyme studies showed that mannitol was synthesized via the reduction of fructose-6-phosphate and not by the direct reduction of fructose. If the cell yield from glucose was assumed to be 50% and the theoretical conversion efficiency from glucose to polyols was 90%, as calculated from the energy balance, then 34% of the glucose carbon was used for growth and 53% was used for polyol formation.