应用离体叶片法鉴定棉花种质抗螨性的研究

应用离体叶片法,对9个棉花种质进行了鉴定,试验结果表明;种质间抗生性和忌避性差异显著;同株棉花不同部位的叶片对朱砂叶螨的抗生性无显著性差异。通过对叶螨在不同棉花种质上种群增长动态进行系统聚类,可将9个棉花种质划分为3类:斯字棉825-91、杞县86789、鄂棉314、苏联8911为1类,中棉164、潼南接龙棉、新库861517-2、南农NAC90-2为1类,美棉7-15独立为1类。依据朱砂叶螨在不同种质上的种群增长曲线和高峰期螨量增长倍数,可将9个种质划分为3个类型;斯字棉825-91、新库861517-2为抗性类型,潼南接龙棉、美棉7-15、南农NAC90-2为感性类型,其余为中抗类型。从忌避性看:斯字棉825-91、美棉7-15表现出较高的忌避性。     

蜂花粉抗脑衰老的实验动物研究

蜂花粉抗脑衰老的实验动物研究蒋滢,杨炳华,黄美英苏州医学院生化教研室苏州２１５００７２探索衰老机制,寻求延缓衰老的有效途径是生命科学中的重大问题,也是亟待解决的实际问题。脑是指挥全身一切活动的中枢,脑组织特别容易遭受自由基及活性氧的损伤,因此防治脑衰...     

大鼠免疫性血小板减少模型的研究

采用注射兔抗大鼠血小板血清（ＡＰＳ）方法,建立了大鼠免疫性血小板减少模型。大鼠腹腔注射１：４稀释的ＡＰＳ（０．７ｍｌ／２００ｇ体重）,连续３ｄ,可使血小板数量显著降低,其降低率为８１±９％（ｎ＝１２）,且其骨随巨核细胞增生活跃,但注射ＡＰＳ后对血中红细胞数和白细胞数无明显影响．在注射ＡＰＳ的同时,给予大鼠灌胃强的松（１ｍｇ／２００ｇ体重）,可抑制ＡＰＳ所致的血小板减少的下降程度,并促进停止注射ＡＰＳ后血小板数的恢复。以上结果表明,该模型符合免疫性血小板减少性紫癜的病理特征。     

The 5[prime] Flanking Regions of Vicilin and Napin Storage Protein Genes Are Down-Regulated by Desiccation in Transgenic Tobacco

Drying of seeds, when imposed prematurely, elicits a switch in metabolism; events unique to development, such as synthesis of storage protein, are terminated, whereas syntheses associated with germination and growth are initiated. To determine the role of desiccation in down-regulating the expression of genes for storage proteins, the desiccation responsiveness of the 5[prime] and 3[prime] regulatory regions of the genes encoding the pea storage protein vicilin and the Brassica napus storage protein napin was tested in transgenic tobacco seed. Chimeric genes were introduced into tobacco; these genes consisted of the coding region of the reporter gene for [beta]-glucuronidase (GUS) and 5[prime] and/or 3[prime] regions from the vicilin or napin genes or, as controls, the same regions derived from constitutively expressed genes, presumed to be desiccation insensitive. In transgenic seed expressing the gene constructs containing the vicilin or napin promoters, GUS activities declined during late seed development, and more dramatically, after imbibition of mature dry seed or prematurely dried seed. In contrast, GUS activities increased after seed rehydration when the constitutive viral promoter replaced the storage-protein gene 5[prime] region. Transient expression assays support the hypothesis that premature drying down-regulates the expression of the storage-protein gene promoter. Following desiccation, this region may become insensitive to positive controlling factors; alternatively, changes to trans-acting factors may occur.     

Intracellular interference of tick-borne flavivirus infection by using a single-chain antibody fragment delivered by recombinant Sindbis virus.

A single-chain antibody fragment that identifies a neutralizing epitope on the envelope protein of louping ill and some other tick-borne flaviviruses was previously expressed in soluble form from bacteria and shown to be functionally active in vitro. To see whether or not the single-chain antibody could bind and inactivate infectious virus in vivo, we have used recombinant Sindbis virus as a delivery vehicle for intracellular expression of the antibody fragment. The variable genes and interchain linker encoding the single-chain antibody were cloned into a double subgenomic Sindbis virus expression vector to generate recombinant Sindbis virus. Infection with this recombinant Sindbis virus provided high-level cytoplasmic expression of the antibody fragment in mammalian cells. We demonstrate (i) that the antibody fragment was antigen binding and (ii) that louping ill virus infectivity was significantly reduced in the presence of intracellular antibody expressed by the superinfecting recombinant Sindbis virus.     

Caloric Restriction: Conservation of in Vivo Cellular Replicative Capacity Accompanies Life-Span Extension in Mice

In male mice of a long-lived hybrid strain (B6D2F1), long-term 40% caloric restriction (CR) extended both mean and maximum life spans by 36 and 20%, respectively, over that of ad libitum fed (AL) controls. Measurements of entry into S-phase were made in vivo of six different cell types in five different organs using 2-week exposures to BrdU. The labeling index (L.I.) in all organs studied was lower in young CR mice than in young AL fed mice. In most cases, the L.I. in AL mice fell to the levels of that in the CR mice by 13 months of age, and the two groups then remained so through old age. However, when the L.I. was measured in old CR mice which had been placed on the AL diet for a period of 4 weeks (this was termed refeeding (RF)), it was found to be above that of similar age AL or CR mice and almost at the level of young AL mice. This was still true, but to a lesser degree, in a repeat study using an 8-week period of RF. In a separate but parallel in vitro study (companion paper, this volume), the superiority of CR over AL for retention of cellular replication capacity was confirmed by clone size distribution measurements made in several cell types in mice of several age groups. These results indicate that: (1) the rate of cell replication in AL diet mice diminishes greatly by early middle age in all organ sites studied and then plateaus or declines much more slowly; (2) CR broadly preserves in vivo cellular replicative capacity but often requires the energy levels provided by a switch to AL feeding to demonstrate this late in life; (3) accordingly, the replicative deficit in AL fed mice appears to be cumulative and is significant only in old age. The mechanism(s) involved is yet to be discovered but may be related to, or even the same as, that which extends life spans in CR animals. Correspondingly, and with corroborative data from our in vitro companion study, (W. R. Pendergrass et al., 1995. Exp. Cell. Res. 217, 309-316), we suggest that cell populations sustain an accrual of biochemical damage or physiological alterations which increasingly limit their replicative capacity as the animal ages, and that CR reduces the accrual of this damage.     

Ras transformation results in an elevated level of cyclin D1 and acceleration of G1 progression in NIH 3T3 cells.

Ectopic overexpression of v-H-Ras protein in NIH 3T3 cells resulted in cellular transformation and an acceleration of G1 progression of these cells. A shortened G1 phase was found to be associated with an increased level of cyclin D1 but not cyclin E protein. Using an antisense blocking method, reduced synthesis of cyclin D1 in v-H-Ras transformants resulted in a slower G1 progression rate of these cells. Although constitutive overexpression of cyclin D1 in NIH 3T3 cells accelerated G1 progression, cells remained untransformed. Furthermore, inhibition of cyclin D1 synthesis greatly impaired the soft-agar cloning efficiency of v-H-Ras transformants. These results suggest that increased expression of cyclin D1 is necessary but not sufficient for the transforming activity of v-H-Ras. Similar effect on cell cycle progression was also observed in Raf-transformed cells. In addition to cyclin D1, cyclin E protein was found to be elevated in Src transformants. This may account for the further shortening of the G1 phase of these cells. Activation of an additional Ras-independent pathway was suggested to be responsible for the further acceleration of the G1 phase in Src transformants.     

Characterization of electron transfer reactions of microperoxidase assembled at short-chain thiol-monolayers on gold

In this study thiol-monolayers were used in order to modify gold and provide suitable chemical functionalities for the immobilization of the small redox-active haem-containing peptide, microperoxidase (MP-11). Initially, we assembled a variety of thiol-containing species on the gold electrodes and measured a series of electron transfer reactions, each characteristic of the surface-modifier. Using suitable immobilization strategies, we subsequently covalently bound MP-11 to appropriate monolayers and found two characteristic electrochemical responses (i.e. using MP-11 bound to mercaptopropionic acid, redox peaks were seen at E^0′ = −315 mV and at +179 mV versus Ag|AgCl, with the former being attributed to the haem and the latter with the thiol monolayer). Exposure of the peptide-thiol surface to UV irradiation resulted in cleavage of the Au---S bond, leading to a decrease in the magnitude of both responses. Our work is supported by corroborative evidence showing the immobilization of the peptide, obtained using both X-ray photoelectron and reflectance Fourier transform infra-red spectroscopies. We hypothesize that differences in the ionic charges on the protein backbone account for the shift in E^0′ for MP-11, as observed in our system, when compared to that found for MP-11 immobilized by different strategies.     

The maize actin-depolymerizing factor, ZmADF3, redistributes to the growing tip of elongating root hairs and can be induced to translocate into the nucleus with actin

The maize actin depolymerizing factor, ZmADF3, binds G-and F-actin, and increases in vitro actin dynamics. Polyclonal antibodies have been raised against ZmADF3 and these detect a single band of approximately 17 kDa in all maize tissues examined, with the exception of pollen. In the development of root hairs, the distribution of ZmADF3 is related to actin reorganization. In the early stages of hair development, ZmADF3 is distributed throughout the cytoplasm. As the hair emerges and the microfilament bundles redirect to the outgrowth there is a simultaneous redistribution of ZmADF3 which now concentrates at the tip of the emerging hair and remains in this position as elongation proceeds. These observations show that ZmADF3 localizes to a region where actin is being remodelled during tip growth. After cytochalasin D treatment which disrupts actin filaments, short rods of ZmADF3 and actin appear in the nucleus suggesting that ZmADF3 may function by guiding actin to sites of actin polymerization.     

广西和湖南的大瓣鱼科化石

详细记述了广西博白和湖南长沙中泥盆世的大瓣鱼科化石,依其特征建立一新属——广西瓣甲鱼Guangxipetalichthysgennov,该属头甲骨片排列型式与澳大利亚的Shearsbyaspis较为接近。同时讨论了鱼化石动物群及相关的地层问题。