几种因素对油菜茎尖培养中玻璃化作用的影响

按前文[植物生理学通讯,1990(3):35]方法继续研究几种影响油菜(Brassica napus )茎尖培养中玻璃化作用的因素,获得结果列于表1。     

茎用芥菜的离休培养及植株再生

植物名称:茎用芥菜(Brassica juncea var.tumida)。材料类别:幼叶、子叶。培养条件:以MS为基本培养基,诱芽培养基为:(1)MS BA 2mg/L(单位下同) NAA 0.2;(2)MS BA2 NAA0.5;(3)M8 BA4 NAA0.1.(4)MSS BA4 NAA 0.2;(5)MS BA4 NAA 1.0。生根培养基为:(6)MS NAA 0;(7)MS NAA 0.1;(8)MS NAA 0.5;(9)MS     

Competency for graviresponse in the leaf-sheath pulvinus of Avena sativa: onset to loss

The development of the leaf-sheath pulvinus of oat (Avena sativa L. cv. Victory) was studied in terms of its competency to respond to gravistimulation. Stages of onset of competency, maximum competency and loss of competency were identified, using the length of the supertending internode as a developmental marker. During the early phases in the onset of competency, the latency period between stimulus and graviresponse decreased and the steady state response rate increased significantly. When fully competent, the latency period remained constant as the plant continued to develop, suggesting that the latency period is relatively insensitive to quantitative changes (e.g., in carbohydrate or nutrient availability) at the cell level within the plant. In contrast, the response rate was found to increase with plant development, indicating that graviresponse rate is more strongly influenced by quantitative cellular changes. The total possible graviresponse of a single oat pulvinus was confirmed to be significantly less than the original presentation angle. This was shown to not result from a loss of competency, since the graviresponse could be reinitiated by increasing the presentation angle. As a result of the low overall graviresponse of individual pulvini, two or more pulvini are required to bring the plant apex to the vertical. This was determined to occur though the sequential, rather than simultaneous, action of successive pulvini, since a given pulvinus lost competency to gravirespond shortly after the next pulvinus became fully competent.     

齿龈内阿米巴生态的研究

齿龈内阿米巴是Gros氏从人牙垢中首次发现。后由Von Prowazek(1904)作了描述。许多学者认为它是非病源原虫。国内将其列入“罕见”人体寄生虫。但我们对内蒙古医学院口腔科门诊病人及正常人作阿米巴感染与疾病关系调后证明其在人群中感染普遍并与牙周病有关。为了解其流行与环境关系而对其生态进行研究。     

霍乱弧菌肠毒素基因在大肠杆菌的表达

霍乱毒素基因在大肠杆菌获得了表达,在大肠杆菌中产生的毒素,具有霍乱毒素同样的生物活性、抗原性和免疫原性。但它产生的霍乱毒索,90％是保持在胞内的,其毒性可被胰酶激活。     

L-精氨酸产生菌诱变育种的研究

本文报道了L-精氢酸产生菌诱变育种的研究结果。以谷氨酸产生菌钝齿棒状杆菌AS1．542为出发菌株,经亚硝基胍多次逐级诱变,获得了一株能够积累大量L-精氨酸的菌株971.1。该菌属于组氢酸缺陷型,并具有对磺胺孤的抗药性。在以葡萄糖为碳源、硫酸铵为氮源的培养基中直接发酵四天,产酸最高可达25·2 mg／ml,并具有较高的产酸稳定性。     

带坐骨神经的蟾蜍离体脊髓标本的制作

离体蟾蜍脊髓标本制作方法简单,反应稳定。由于冷冻麻醉 故手术时不需要麻醉剂和肌松剂。并可严格控制外环境的变化(PH、温度、药物剂量)。施加药物时不受血脑屏障影响,进行神经反射机理研究时不受高位中枢及外周感受器影响,故为进行电药理、电生理学研究的一个较为理想的标本。 本文所介绍的标本带有一条坐骨神经干,尤其利于进行电生理学实验。     

Diazinon resistance, fluctuating asymmetry and fitness in the Australian sheep blowfly, lucilia cuprina

Genetic evidence suggests that the evolution of resistance to the insecticide diazinon in Lucilia cuprina initially produced an increase in asymmetry. At that time resistant flies were presumed to be at a selective disadvantage in the absence of diazinon. Subsequent evolution in natural populations selected modifiers to ameliorate these effects. The fitness and fluctuating asymmetry levels of resistant flies are currently similar to those of susceptibles. Previous genetic analyses have shown the fitness modifier to co-segregate with the region of chromosome III marked by the white eyes, w, locus, unlinked to the diazinon resistance locus, Rop-1, on chromosome IV. This study maps the asymmetry modifier to the same region, shows, as in the case of the fitness modifier, its effect to be dominant and presents data consistent with the fitness/asymmetry modifier being the same gene (gene complex). These results suggest changes in fluctuating asymmetry reflect changes in fitness.     

Genetic Analysis of the Heterochromatin of Chromosome 3 in Drosophila Melanogaster. II. Vital Loci Identified through Ems Mutagenesis

Chromosome 3 of Drosophila melanogaster contains the last major blocks of heterochromatin in this species to be genetically analyzed. Deficiencies of heterochromatin generated through the detachment of compound-3 chromosomes revealed the presence of vital loci in the heterochromatin of chromosome 3, but an extensive complementation analysis with various combinations of lethal and nonlethal detachment products gave no evidence of tandemly repeated vital genes in this region. These findings indicate that the heterochromatin of chromosome 3 is genetically similar to that of chromosome 2. A more thorough genetic analysis of the heterochromatic regions has been carried out using the chemical mutagen ethyl methanesulfonate (EMS). Seventy-five EMS-induced lethals allelic to loci uncovered by detachment-product deficiencies were recovered and tested for complementation. In total, 12 complementation groups were identified, ten in the heterochromatin to the left of the centromere and two to the right. All but two complementation groups in the left heterochromatic block could be identified as separate loci through deficiency mapping. The interallelic complementation observed between some EMS-induced lethals, as well as the recovery of a temperature-sensitive allele for each of the two loci, provided further evidence that single-copy, transcribed vital genes reside in the heterochromatin of chromosome 3. Cytological analysis of three detachment-product deficiencies provided evidence that at least some of the genes uncovered in this study are located in the most distal segments of the heterochromatin in both arms. This study provides a detailed genetic analysis of chromosome 3 heterochromatin and offers further information on the genetic nature and heterogeneity of Drosophila heterochromatin.