细胞因子基因转导对人乳腺癌细胞MHC抗原及细胞膜糖蛋白表达的影响

为探讨细胞因子基因(人IL-2、IL-6)转导对于肿瘤细胞膜MHC抗原及细胞膜糖蛋白表达调控的影响,本文利用脂质体介导的方法,将含人IL-6、IL-2基因的逆转录病毒载体分别导入人乳腺癌细胞系MCF-7细胞中,采用间接免疫荧光染色流式细胞仪测定法,对基因转导的瘤细胞细胞膜糖蛋白及MHC抗原表达进行测定。结果表明经两种基因修饰的MCF-7细胞MHCⅠ型抗原表达均获得增强,此外,基因转导细胞可程度不同地表现出细胞膜多种糖蛋白表达的变化。提示肿瘤细胞膜抗原及糖蛋白表达的改变可能是细胞因子基因转导影响肿瘤细胞免疫原性的重要结构基础。     

Morphological forms and viability of Campylobacter species studied by electron microscopy.

Electron microscopic studies of Campylobacter revealed that different morphological forms predominate at different parts of a colony. At the periphery, cells were almost all spirals, while in the center of the colony cells were mainly coccus shaped. Unusual ring-shaped cells, "donuts", were observed in the raised, peripheral region of the colony. Donut or ring forms have not previously been reported for Campylobacter organisms. Our data indicate that young or actively growing cells are mainly spiral shaped. Older cells undergo a degenerative change to coccoid forms. The donut shape appears to be an intermediate stage between spirals and cocci. Comparisons of plate counts of actively growing and inactive cells confirmed that coccoid cells are probably nonviable.     

Value of cane trash in nitrogen nutrition of sugarcane

The significance of trash containing 0.3 to 0.5% N in the N nutrition of sugarcane (Saccharum hybrid sp.) was investigated in pot- and field experiments using¹⁵N-labelled trash. The data obtained from the pot study with 2 silty-clay loams (a Humic Nitosol and a Humic Acrisol) showed that surface-applied trash (10 tonnes/ha), although ground to pass a 1-mm sieve, contributed less than 10% of N removed by sugarcane. Uptake of trash N was most active during the initial 6 months of the experiment though at the end of the study period of 18 months less than 15% of trash N was altogether recovered by sugarcane. In the absence of fertilizer N in a field study on the Humic Acrisol (C/N ratio 22), unground trash (5 tonnes. ha⁻¹) depressed soil N uptake by sugarcane by immobilizing available soil N. The field study moreover confirmed that the contribution of trash N in the supply of N to sugarcane is negligible. The value of trash would reside in its capacity to increase over the long term the organic matter level in the soils.     

Changes in repeat number, sequence, and reading frame in S-antigen genes of Plasmodium falciparum.

The S antigens from different isolates of Plasmodium falciparum exhibit extensive size, charge, and serological diversity. We show here that the S-antigen genes behave as multiple alleles of a single locus. The size heterogeneity results from different numbers, lengths, and/or sequences of tandem repeat units encoded within the S-antigen genes. Two genes studied here encode antigenically different S antigens but nevertheless have closely related tandem repeat sequences. We show that antigenic differences can arise because repeats are translated in different reading frames.     

Phosphoinositide breakdown and evidence for protein kinase C involvement during human NK killing

Conjugation between human NK cells and susceptible target cells (K562 and Jurkat) leads to breakdown of inositol lipids in the effector cells but not when conjugated with resistant target cells. Extracellular Ca2+ is required for this activation. Sphingosine inhibits NK killing in both normal and IL-2-activated NK cells. Phorbol esters, TPA, and PDBU enhanced NK killing at low concentrations, where 4-alpha-PDIDE did not. The diacylglycerol derivative OAG increased NK cell killing and activated PKC from human lymphocytes. These results strongly suggest that phosphoinositide breakdown and activation of PKC is involved in NK killing.     

短尾猴和日本猴雄性性行为的比较研究

本文比较研究了短尾猴和日本猴的雄性性行为。短尾猴属单次爬跨射精型种类,每次交配平均持续23.2秒,日本猴属多次爬跨射精型种类,每次交配平均持续8.2分,交配期间雄性平均爬跨雌性lO.6次才能达到射精。短尾猴第1顺位雄性是群中的主要交配者,它占有交配总数的70.9 %;而日本猴第5顺位以下的雄性占交配总数的64%。交配中,两种猴雄性间相互打搅行为的发生频率大致相当。短尾猴高顺位雄性的打搅行为能使低顺位雄性的交配中断,但日本猴高顺位的打搅行为只能使低顺位雄性交配的54.3%中断。