河南浮戏山植物区系地理及其近缘关系

浮戏山有种子植物９６科３１３属５５２种，区系成分以北温带、泛热带和旧世界温带三种成分为主，其次是东亚和东亚北美间断成分，植物区系具有明显的温带性质。以植物地理成分为指标，将浮戏山和全国其它１９个地区进行系统聚类分析，结果表明，浮戏山植物区系成分和与其同处于中纬度地区的河南境内的桐柏山、大别山、小秦岭、老君山及山西中条山山东泰山最为相似，而与高纬度地区的长白山。低纬度地区的广西大瑶山和海南五指山最为     

福建水牛肉孢子虫形态学的考察

用光镜和电镜观察了福建水牛的肉孢子虫形态,证明有两型的孢囊。大型包囊的原级囊壁有菜花状突起,顶端呈树枝状分支,内有环纹小纤丝、微管和电子致密颗粒,经鉴定是梭状肉孢子虫(Sarcocystis fusiformis)。小型包囊有两种,其中一种的囊壁外侧有倾斜的放射状突起条纹,其原级囊壁具有斜状突起的绒毛,鉴定为李氏肉孢子虫(S.Levinei),另一小型包囊的囊壁光滑,无放射状条纹,囊内隔板不明显,所含的慢殖子较少,与李氏肉孢子虫有明显差异,故暂不定种名。     

关于武汉大气污染和室内冬冷夏热的对策

采取合理的城市规划,限制现有工厂向大气排放污染物,选择建筑物的最佳朝向和建筑气候的对策,可以在不同程度上解决武汉大气污染和室内夏热冬冷的问题。这种对策的优点是:耗资小,见效快,一劳永逸。     

Tumour necrosis factors alpha and beta inhibit virus replication and synergize with interferons

Tumour necrosis factor (TNF) and lymphotoxin were initially described as tumoricidal proteins that are produced by activated macrophages and lymphocytes, respectively. Since TNF and lymphotoxin are structurally related, bind to the same cell surface receptor and have indistinguishable biological activities, they have been designated as TNF-alpha and TNF-beta, respectively. The multiple activities of these molecules indicate their importance in immunoregulative responses. Here we report that both TNF-alpha and TNF-beta have antiviral activity and synergize with interferons (IFNs) in the induction of resistance to both RNA and DNA virus infection in diverse cell types. These effects of TNFs are not due to the induction of IFN synthesis. Virus-infected cells are selectively killed by TNFs and this activity is accelerated by IFN-gamma. The production of TNFs is induced by viruses, further suggesting the importance of TNFs in the physiological antiviral response.     

Latent synaptic pathways revealed after tetanic stimulation in the hippocampus

Synaptic plasticity may result from changes at existing synapses or from alterations in the number of functional synaptic connections. In the hippocampus excitatory synaptic strength is persistently enhanced after tetanic stimulation. Here we report that latent synaptic pathways may also become functional. Simultaneous intracellular recordings were made from pairs of CA3 pyramidal cells in slices from guinea pig hippocampus. After stimulating afferent fibres repetitively, polysynaptic excitatory pathways between previously unconnected cells became apparent. The efficacy of recurrent inhibitory circuits was also reduced. The loss of inhibitory control is of interest because latent excitatory pathways are revealed after pharmacological suppression of inhibition. This plasticity in local synaptic circuits leads to the emergence of synchronous firing in groups of CA3 cells. The formation of groups of associated cells and the ability of some cells to initiate synchronous firing in a larger cell group through recurrent pathways is reminiscent of several models of information storage and recall in the cortex.     

The effects of sodium and amiloride on the motility of the caudal epididymal spermatozoa of the rat

Summary The forward motility of the rat caudal epididymal spermatozoa has been studied in different Na⁺ concentrations. When spermatozoa were suspended in a completely Na⁺-free solution, the forward motility suffered a progressive fall and after 3 h was completely suppressed. This effect was fully reversible on resuspending the spermatozoa in a solution containing Na⁺. Amiloride caused a fall in motility and the effect was similar to that of Na⁺ removal. The inhibition by amiloride of the motility was concentration dependent and the dose response curve showed an IC₅₀-value of about 5×10^–5 M. The role of Na⁺ influx in the maintenance of sperm motility was discussed.This work was supported by the World Health Organization.The technical assistance of Mr C.M. Li and the gift of amiloride from Merck, Sharp and Dohme are gratefully acknowledged.