脊髓苯环立啶受体的心血管效应与去甲肾上腺素能系统

本文应用受体阻断、高效液相,6-OHDA 化学损毁神经末梢和放射自显影等多学科技术方法,探讨脊髓苯环立啶受体的心血管效应与去甲肾上腺素能神经系统的关系。结果表明,哌唑嗪、育亨宾均可对抗 ith PCP 的降压和减慢心率作用,ith PCP 产生降压和减慢心率作用时,脊髓脑脊液内 MHPG 的含量升高;用6-OHDA 损毁脊髓 NA 能神经末梢后,ith PCP的降压和减慢心率作用大为减弱,脊髓 PCP 受体密度亦同时大为降低。可以认为,脊髓内有 PCP 受体分布于 NA 能神经末梢上,促进 NA 释放或抑制 NA 重摄取,可能是脊髓 PCP 受体产生心血管抑制效应的重要机理。     

用体外免疫法建立人—人抗流行性乙型脑炎病毒杂交瘤细胞株

利用单克隆抗体(McAb)进行病毒病的治疗是人们所关心的一个重大课题。 流行性乙型脑炎(乙脑)是一种严重威胁人民健康的急性传染病,病死率高,后遗症严重。国内外目前尚无特效疗法。陈伯权等用乙脑病毒皮下或腹腔感染3周龄小白鼠24、48小时及5天后,分别用乙脑病毒51-8McAb进行治疗,平均治愈率分别为78％、73％及22％。     

Germin-Like Polypeptides Increase in Barley Roots during Salt Stress

The 26 kilodalton, isoelectric point 6.3 and 6.5 (Gs1 and Gs2) polypeptides that increase in barley (Hordeum vulgare L.) roots during salt stress were isolated and identified. Both Gs1 and Gs2 had high sequence similarity to germin, a protein that increases significantly in germinating wheat seeds. Like germin, Gs1 and Gs2 were resistant to proteases and were glycosylated. Immunoblots were probed with antibodies to Gs1 and Gs2 to determine the distribution of these polypeptides among organs and cell-free fractions. Gs1 and Gs2 were present in roots and coleoptiles, but absent from leaves. In roots, Gs1 and Gs2 were present in the mature region, but not the tip. Gs1 and Gs2 increased in roots, but decreased in coleoptiles in response to salt stress. Gs1 and Gs2 were distributed among the soluble, microsomal, and cell wall fractions of roots, but the majority of Gs1 and Gs2 was present in the soluble fraction. Although Gs1 and Gs2 were heat stable, their synthesis was not affected by abscisic acid treatment. Gs2 accumulated during abscisic acid treatment, whereas Gs1 did not. However, a 25.5 kilodalton, isoelectric point 6.1 polypeptide that was immunologically related to Gs1 did accumulate with abscisic acid treatment.     

西双版纳傣族“龙山”的生态学意义

傣族“龙山”是西双版纳地区傣族的民族植物文化中的一例。其概念是“神居住的地方”,在这个地方的动植物都是神的家园里的生灵,是神的伴侣,是不能砍伐、狩猎和破坏的。人     

Phosphorylation of ankyrin decreases its affinity for spectrin tetramer

The effects of phosphorylation on the interaction between spectrin and ankyrin were investigated. Spectrin and ankyrin were phosphorylated using purified human erythrocyte membrane and cytosolic (casein kinase A) kinases. These two kinases have similar properties as well as activities toward spectrin and ankyrin. Both kinases catalyzed the incorporation of about 2 mol of phosphate/mol of spectrin and about 7 mol of phosphate/mol of ankyrin. These phosphates were incorporated primarily into seryl and threonyl residues of the proteins. The phosphopeptide maps of ankyrin phosphorylated by the membrane kinase and casein kinase A were identical. Binding studies indicate that ankyrin exhibits different affinities for spectrin dimers (KD = 2.5 +/- 0.9 X 10(-6) M) and tetramers (KD = 2.7 +/- 0.8 X 10(-7) M). These dissociation constants were not appreciably affected by the phosphorylation of spectrin. On the other hand, phosphorylation of ankyrin was found to significantly reduce its affinity for either phosphorylated or unphosphorylated spectrin tetramers (KD = 1.2 +/- 0.1 X 10(-6) M) but not spectrin dimers (KD = 2.5 +/- 0.4 X 10(-6) M). The same results were obtained using either the membrane kinase or casein kinase A as the phosphorylating enzyme. The above observation suggests that ankyrin phosphorylation may provide an important mechanism for the regulation of the erythrocyte membrane cytoskeletal network.     

元江干热河谷山地五百年来植被变迁探讨

元江河谷是云南省最干热地区之一,在海拔800—900米以下的山地上广泛分布着稀树灌草丛。根据《元江府志》(1714年编纂)、《元江州志》(1826年编纂)、《元江志稿》(1922年编篡)及对现存植被的考察,本文探讨了元江干热河谷山地五百年来植被的变迁。 元江县森林复盖率的减少与人口的增加有密切关系,十七世纪中期以前,森林复盖率在75％以上,十八、十九世纪时为70％左右,1958年为61.5％,1975年为27.3％,至1982年则为19.3％。研究表明,在十九世纪以前,这个地区分布的主要植被是热带季雨林,甚而热带季节雨林,以后热带稀树灌草丛则迅速发展。植被的历史变化与土壤流失密切相关。植物群落的演变是由以乔木树种为优势演变为以灌木种类为优势,再演变为以多年生草木植物为优势,而最后则成为裸地。本文也讨论了这个地区植被恢复的方法。     

兴安落叶松结实规律与长短枝习性的关系

1987年5月,大兴安岭林区发生的特大森林火灾,实属世界罕见,火灾面积达1.0×10~6ha 多。大量的火烧迹地亟待更新、无论是人工更新还是人工促进天然更新,其中关键的问题之一是种子的来源,在大兴安岭地区,兴     

Analysis of Lactobacillus phages and bacteriocins in American dairy products and characterization of a phage isolated from yogurt.

Yogurt and acidophilus milk that contain Lactobacillus acidophilus could promote human health because L. acidophilus can inhibit enteric and food-borne microbial pathogens. To evaluate the stability of diary L. acidophilus cultures, we studied whether some diary lactobacilli could be inhibited by phages or bacteriocins released by other dairy lactobacilli. From 20 yogurts and two acidophilus milks purchased at local food markets, 38 Lactobacillus strains were isolated. Eight Lactobacillus type strains were used as controls. With mitomycin induction and agar spot assay, phages and bacteriocins were isolated from these strains and their activities were analyzed. Lactobacillus strains from 11 yogurts released phages, while the strains from most of the remaining products released bacteriocins. One phage, designated phi y8, was characterized. It was spontaneously released from its host strain L. acidophilus Y8, at a rate of about 10(4)/ml. This phage lysed nine other dairy Lactobacillus strains tested. It had a burst size of 100, an elongated prolate head of 39 by 130 nm, a long, flexible but noncontractile tail of 300 nm, and a 54.3-kb linear double-stranded DNA. DNA fingerprinting analysis indicated that L. acidophilus phages of nine yogurts in this study belonged to the same type as phi y8. Although they may be sensitive to bacteriocins, all lysogens resisted further phage attacks, whereas most nonlysogens were sensitive to both phages and bacteriocins. Therefore, Lacotbacillus cultures of some American yogurts and acidophilus milks may be unstable or unsafe because they can either be inhibited by phages or bacteriocins or release them to inhibit lactobacilli or other diary products.