Expression of a microinjected immunoglobulin gene in the spleen of transgenic mice

Transgenic mice were produced by microinjection of a rearranged, functional immunoglobulin kappa gene into fertilized mouse eggs and implantation of the microinjected embryos into foster mothers. Mice that integrated the injected gene were mated and the DNA, RNA and serum kappa chains of their offspring were analysed. The data from offspring of three different transgenic mice indicate that the microinjected gene is expressed in the spleen, but not the liver of mice which inherited the injected gene.     

High frequency of unequal recombination in pseudoautosomal region shown by proviral insertion in transgenic mouse

The mammalian X and Y chromosomes, in contrast to the autosomes, pair during male meiosis only near the telomeres. Alleles localized in this region can undergo reciprocal exchange during meiosis. Because such sequences do not show strict sex-linked inheritance, they have been termed pseudoautosomal. In man, several DNA sequences have been described which show pseudoautosomal transmission and which are localized in the pairing region at the ends of the short arms of both the X and Y chromosomes (refs 6-9, and D. Page, unpublished results). We now show that the transgenic mouse strain, Mov-15, contains a single Moloney murine leukaemia virus (M-MuLV) genome in its germline, and genetic evidence indicates that the provirus is integrated into the pseudoautosomal region of the sex chromosome. Proviral copies are lost or gained in 7% of male meioses in this strain, and mouse sequences flanking the provirus are tandemly repeated and highly variable. We conclude that unequal recombination events occur with high frequency in the pairing region, possibly because of the presence of repeated sequences.     

Selective activation of Lyt 2+ precursor T cells by ligation of the antigen receptor

Resting T lymphocytes may be activated either physiologically, by the specific recognition of antigen in association with molecules encoded by the major histocompatibility complex (MHC), or non-physiologically using mitogens such as concanavalin A (Con A). The former activation process is difficult to analyse because resting precursor T cells specific for a particular antigen-MHC combination can only be isolated in the presence of a large excess of bystander cells of irrelevant specificity; clonal populations of uniform specificity are not useful for studying the activation of naive T cells because there is no reason to believe that such cloned cells ever return to the state of resting precursors. Mitogens may activate a large fraction of resting T cells, but analysis is again complicated because the target molecule(s) of most mitogens is unknown and the relationship of this kind of activation to physiological induction by antigen plus MHC molecules remains unclear. By using a monoclonal antibody specific for the antigen receptors on approximately 25% of all T cells of both Lyt 2+ and Lyt 2- subsets, we have studied the induction of lymphokine responsiveness in resting normal T cells. This antibody, immobilized on Sepharose beads, is sufficient to activate Lyt 2+ T cells, but not Lyt 2- T cells, to clonal expansion in the presence of a mixture of lymphokines (10% rat spleen Con A supernatant). We report here that clonal growth of the T cells obeys single-hit kinetics in limiting-dilution microcultures, suggesting that a single cell type is limiting. We conclude that cytotoxic T-lymphocyte (Tc) precursors require only ligation of the antigen receptor before they become responsive to lymphokines, whereas helper T-lymphocyte (Th) precursors require additional signals.     

PMSM伺服控制的数字电流环研究

研究了永磁同步电动机（ＰＭＳＭ）伺服系统的一种新型数字电流环方案，该方案采用了规则采样法生成ＰＷＭ波的比例型电流调节器，提出用前馈补偿和变电流环增益技术才能提高电流调节性能，给出了数字仿真和实验结果。     

一种地面目标的相关跟踪方法

提出了一种用多子模板对目标进行相关跟踪的方法，该方法建立了综合多子模板相关结果、目标跟踪判断及自适应刷新模板等准则，较好地解决了相关跟踪中如何判断目标锁定、部分遮挡、相似目标出现及模板的刷新等问题。     

非共轭齿面鼓形齿联轴器运动分析

建立了非共轭齿面鼓形齿联轴器的内外齿面方程，根据非共轭齿面的啮合条件进行了啮合状态的计算分析，得出了若干运动学分析的结论．     

新型高效冷风机翅片管紧固效果的试验研究

采用网格法测量了冷风机翅片冲压加工的变形量，确定了翅片材料的成形极限。用塑性大应变计测试了不同工况下冷风机翅片管胀管变形的全过程，建立了分析冷风机翅片管紧固效果的特征曲线方法，提出了用宽裕度作为胀头过盈量设计取值的概念，综合评价了不同翅片管的紧固效果。