新疆塔里木柯坪地区上奥陶统凯迪阶串管海绵类化石及其滤食选择性探讨北大核心

奥陶纪是串管海绵早期演化的一个关键阶段,记录了该类群的首次大规模辐射演化事件(属级分类单元达15个)。然而,现有大部分奥陶系串管海绵的报道来自澳大利亚东部和北美等地,在中国至今仅发现了两个属,与前述地区相比研究程度偏低。早期研究主要基于形态学特征对串管海绵进行系统分类描述,对其滤食策略知之甚少,因此制约了对此类海绵在奥陶纪底栖生态系统作用的相关探讨。本文系新疆塔里木柯坪地区奥陶纪串管海绵的首次系统古生物学报道,详细描述凯迪阶(上奥陶统)印干组中保存完好的阔室丛花海绵(Corymbospongia amplia)化石的形态学特征,并通过研究标本外壁微孔孔径的大小分布,探讨其滤食选择性。海绵外壁微孔孔径的分析表明:小型和微型浮游生物可能是其食物的主要来源,而多细胞浮游动物因个体尺寸大于海绵外壁微孔,不能被阔室丛花海绵捕获。本研究为奥陶纪串管海绵古生态学及其地球生物学意义的探讨提供了进一步的依据。     

Formation of heterosymplasts in human reticular cell cultures]

The cell fusion has been studied in human reticular cell cultures J-96 and J-41 treated with the Sendai virus or with polyethylene glycol 1000 and 6000. The J-96 cells have a high alkaline phosphatase activity, in J-41 cells the enzyme is not detectable. No heterogenous alkaline phosphatase activity was seen in the protoplasm of symplasts 18 hours after virus cell fusion. It has been shown with polyethylene glycol treatment that during the fusion of cells J-96 and J-41 the enzyme activity was spreading over the symplast protoplasm.     

Ratio of the antiproliferative action of interferon to the degree of purity of the preparation

The antiproliferative (AP) action of human leukocytic interferon (HLI) of varying degrees of purification was studied and compared in cultures of human cells differing in interferon sensitivity. The concentrated and purified preparations of HLI suppressed the incorporation of 3H-thymidine and mitotic activities of the cultures sensitive to HLI of the cells, affecting, but insignificantly, the proliferation of the resistant cell culture. Poorly purified HLI suppressed the proliferation of both cell types. This indicates that native HLI contains impurities that have an AP action and exerts no antiviral activity.     

Study of the complex formation between alpha- and beta- forms of NAD-kinase and glutamate dehydrogenase and the effect of metabolites on enzyme interaction

The alpha- and beta-forms of rabbit liver NAD kinase were found to differ significantly in terms of their ability to form complexes with glutamate dehydrogenase. The beta-form of the enzyme was shown to form a more stable complex with glutamate dehydrogenase (Kd = 1.5.10(-8) M), whereas the Kd value for the alpha-form is 2.9.10(-7) M. Using two independent methods, it was shown that in the absence of effectors 40% of the beta-form of NAD kinase and up to 20% of the alpha-form are bound to glutamate dehydrogenase. The substrates of NAD kinase markedly activate the complex formation only in the case of the alpha-form of the enzyme. The time needed for this process is also reduced in the presence of the substrates.     

Comparative analysis of analgesic activities of dermorphin, [DPro<Superscript>6</Superscript>]-dermorphin,and their C-terminal tripeptides

Analgesic activities of dermorphin (DM), [DPro⁶]-DM, and their C-terminal tripeptides were comparatively studied. Analgesic activity was evaluated in tail flick, hot plate, tail pinch, formalin, and acetic acid writhing tests describing different levels of organization of pain sensitivity. Intraperitoneal administration of the peptides decreased the pain threshold in all these tests. The C-terminal tripeptides DM_5–7 and [DPro⁶]-DM_5–7 demonstrated analgesics activity comparable or sometimes higher than that of the full-length molecules. The effect of DM, [DPro⁶]-DM, and C-terminals fragments DM_5–7 and [DPro⁶]-DM_5–7 decreased after co-administration with naloxone, which points to the opioid nature of analgesic activity of the peptides.