STRANDEDNESS OF VICIA FABA CHROMOSOMES AS REVEALED BY ENZYME DIGESTION STUDIES

Chromosomes and nuclei isolated from neutral formalin-fixed Vicia faba lateral roots were treated with trypsin, pepsin, RNase, or DNase. Only trypsin affected the morphology of the chromosomes and nuclei. The appearance of the chromosomes after trypsin digestion indicated that each chromatid contained four strands that could be seen with an ordinary light microscope. The experiments are interpreted as indicating that mitotic chromosomes of Vicia faba are multistranded and that the linear continuity of the chromosome is dependent on protein.     

THE EFFECT OF THE CONCENTRATION OF ENZYME ON THE RATE OF DIGESTION OF PROTEINS BY PEPSIN

1. In certain cases the rate of digestion of proteins by pepsin is not proportional to the total concentration of pepsin. 2. It is suggested that this is due to the fact that the enzyme in solution is in equilibrium with another substance (called peptone for convenience) and that the equilibrium is quantitatively expressed by the law of mass action, according to the following equation. See PDF for Equation It is assumed that only the uncombined pepsin affects the hydrolysis of the protein. 3. The hypothesis has been put in the form of a differential equation and found to agree quantitatively with the experimental results when the concentration of pepsin, peptone, or both is varied. 4. Pepsin inactivated with alkali enters the equilibrium to the same extent as active pepsin. 5. Under certain conditions (concentration of peptone large with respect to pepsin, and concentration of substrate relatively constant) the relative change in the amount of active pepsin is inversely proportional to the concentration of peptone and the equation simplifies to Schütz''s rule. 6. An integral equation is obtained which holds for the entire course of the digestion (except for the first few minutes) with varying enzyme concentration. This equation is identical in form with the one derived by Arrhenius for the action of ammonia on ethyl acetate. 7. It is pointed out that there are many analogies between the action of pepsin on albumin solutions and the action of toxins on an organism.     

ASSESSMENT OF BIVALVE INTRACELLULAR DIGESTION BASED ON DIRECT MEASUREMENTS

Two methods of studying intracellular digestive state in bivalvemolluscs, (1) the subjective tubule grading technique and (2)an alternative method based on measurements of digestive tubuleand luminal widths, were compared using data from a starvation/feedingexperiment on the quahog, Mercenaria mercenaria (L.). Measurementsof digestive cell heights or lumen widths could not be directlycompared due to differences in tubule widths within and betweenindividuals (range = 56.6 to 77.4 µm; X = 63.0; SD 4.8(µm) which were unrelated to quahog length. Instead, themean proportion of the tubule width (MPTW) covered by digestivecell cytoplasm was used for comparisons between samples of animals.MPTW covaried directly with the subjectively established proportionof Type II tubules (r = 0.882). The inclusion of data from obliquesections of digestive tubules did not unduly affect statisticalresults . Of 4 sampling schemes compared, a systematic samplingscheme in which measurements were made on only one digestivegland tubule within an area containing a cluster of similartubule types, was shown to be best. ¹Contribution No. 105, Marine Science Institute, NortheasternUniversity, Nahant, MA., 01908 ²Current address: New England Aquarium, Central Wharf, Boston,MA, 02110 USA (Received 28 September 1981;     

单酶切cDNA-AFLP改良法分离草菇冷诱导基因

采用单酶切cDNA-AFLP改良法克隆分离了十条草菇冷诱导基因片段VC7、VC8、VC9、VC10、VC11、VC12、VC13、VC14、VC15、VC16。DNA序列测定结果表明,克隆分离的十条DNA片段分别为504bp、549bp、555bp、301bp、189bp、602bp、605bp、834bp、703bp、1085bp。同源性BLAST程序搜索结果显示,除VC14与粗糙脉孢菌Neurosporacrassa的钙磷型ATP酶基因有较高的同源性外,其余九条DNA片段目前都没有搜索到同源的核酸序列;而其翻译的蛋白质序列,除了VC11和VC15目前未能搜索到同源的蛋白质序列外,其余八条DNA片段翻译的蛋白质序列与粗糙脉孢菌Neurosporacrassa、裂殖酵母Schizosaccharomycespombe、链霉菌Streptomycesavermitilis等的有关蛋白质序列具有较高的同源性。     

侵染长豇豆的豇豆蚜传花叶病毒的鉴定

长豇豆花叶病是辽宁省长豇豆的一种严重病害,1983年我们在沈阳地区获得一个花叶病分离物(CpV-2),在长豇豆上表现为花叶、脉带,黄斑,叶面皱缩、叶缘缺刻及叶尖下卷等症状,人工摩擦接种可侵染豆科、藜科、茄科、胡麻科中的15种植物,在苋色藜、昆诺藜、芝麻和蒙若豆的接种叶上仅产生局部褪绿斑或坏死斑,该病毒的钝化温度为60～65℃(10分钟),稀释限点10~(-3)～10~(-4),体外存活期1～3天(19～20℃),可由桃蚜、豆蚜、大豆蚜以非持久性方式传毒,种子传毒率为4.5～10.5％,病毒仅存在于种胚内,提纯的病毒有侵染性,具有典型的核蛋白紫外吸收光谱,A260nm/280hm为1.910,病毒粒体为线条状,平均长747.4nm,宽13nm,该病毒仅与豇豆蚜传花叶病毒的抗血清呈阳性反应,因此认为,该分离物(CpV-2)系豇豆蚜传花叶病毒(Cowpea aphidborne mosaic virus,CAMV)。     

中国大麦黄花叶病毒分离物的分子变异

１３个供试的中国和英国大麦黄花叶病毒（ＢａＹＭＶ）分离物,经ＲＮＡ１和ＲＮＡ２全基因组不同区域ＤＮＡ片段背地里单构象多态分析（ＳＳＣＰ）,外壳蛋白基因和ＲＮＡ２ ７０ｋＤ基因５端７０５碱基序列分析,以及此７－５碱基ＤＮＡ片段限制性内切酶图谱分析结果,它们的ＲＮＡ１和ＲＮＡ２彼此无一相同,其中ＲＮＡ２变异比ＲＮＡ１更大。由于变异十分复杂,且没有规律性,因而当前通用的分子生物学技术尚不能简单地ＢａＹＭ     

大麦黄花叶病毒单克隆抗体的制备

大麦黄花叶病毒(Barley yellow mosaic virus,BaYMV)广泛分布于西欧、日本和我国长江中下游和东部沿海地区,严重危害了大麦生产,并呈现出不断蔓延扩大的趋势。该病毒经土壤禾谷多粘菌介体感染大麦后,病毒繁殖发病的状况,易受到大麦品种不同、环境温湿度等因素的影响,发病程度的差异很大,而且还发现带毒隐症的大麦品种,使大麦抗源筛选和大麦抗性品种的选育工作受到严重干扰,因此迫切需要建立一种快速、灵敏和准确的检测方法。目前,比较理想的方法是ELISA等免疫学技术。     

EXPERIMENTS BEARING ON THE NATURE OF INTRACELLULAR INCLUSIONS IN PLANT VIRUS DISEASES

The intracellular changes resultant on infection with aucuba mosaic and Hy. III diseases are described and are compared with the cytological effects of tobacco mosaic virus. With the two former viruses, inclusion bodies are formed by the aggregation and fusion of minute particles which appear in the cytoplasmic stream. With tobacco mosaic disease an amoeba-like body is produced and this persists for some weeks before suddenly disappearing again. It is accompanied by striate material all of which ultimately fuses into one large body.
Attempts have been made to parallel these conditions in healthy cells of Solanaceous plants by treatment with substances known to coagulate protoplasm. Almost all the reagents used induced stimulation of the cytoplasmic stream similar to the initial sign of virus infection. With salts of molybdic acid, all the cytological abnormalities due to aucuba mosaic or Hy. III disease have been imitated. Treatment with lactic acid induces the formation of amoeboid bodies like the X-bodies of tobacco mosaic, but these bodies persist for only a few hours.
Attempts have also been made to inhibit the formation of inclusion bodies induced by several different diseases in a number of hosts but no success was obtained.
The experiments support the view that the intracellular inclusions of plant virus diseases are essentially products of the host cell.     

影响菜豆普通花叶病毒种子传毒的因素

研究了影响菜豆普通花叶病毒(BCMV)种子传毒的一些因素,不同品种,不同感染时期种子的传毒率有显著差异,苗期感病的植株,不同荚位的种子传毒率是:下部>中部>上部,花期感病者则是:中部>上部>下部,感病植株的斑驳荚种子传毒率,依品种的不同,比无斑驳荚者高3.2～9.3倍。     

DIGESTION OF MICROCYSTIS AERUGINOSA BY OREOCHROMIS MOSSAMBICUS

SUMMARY

The mean assimilation efficiency of aquarium acclimatized Oreochromis mossambiaue fed on a diet of Microcystis aeruginosa collected from Hartbeespoort Dam was determined as 50,8% for total organic matter, 63,7% for protein and 75,5% for phosphorus. Transmission electron microscopic examination of faeces of fish fed on M. aeruginosa, revealed that most Microcystis cell walls had become permeable allowing cell contents to leach out. Further digestion resulted in the break down of the cell wall structure. Up to 25% of the cells, however, appeared intact after passing through the fish. Fish fed on a diet of M. aeruginosa lost mass initially, but after 21 days showed a slight gain in mass. The high protein content of M. aeruginosa nay have inhibited efficient metabolism and would have led to reduced growth in fish.     

生物发光法测定溶脲脲原体内微量ATP

目的　监测在液体培养基中生长的溶脲脲原体(Uu)细胞内微量ATP的变化趋势,方法　运用生物化学发光技术,建立ATP定量法。结果　Uu标准血清型1(U     

蚕豆种子超氧物歧化酶的纯化及性质

蚕豆种子粗提液经乙醇－氯仿混合物处理、丙酮沉淀、ＤＥＡＥ－纤维素层析和Ｓｅｐｈａｒｏｓｅ６Ｂ层析,获得比活性为２８５２单位ｍｇ－１蛋白的超氧物歧化酶．经聚丙烯酰胺凝胶电泳证明酶已纯化到均一程度．该酶对ＫＣＮ和Ｈ２Ｏ２敏感,说明它为Ｃｕ,Ｚｎ－ＳＯＤ．酶分子量和亚基分子量分别为３１０００和１４４００,说明它是由两个相同亚基组成。该酶在７０℃以下和在ｐＨ５—９条件下稳定．紫外区最大吸收峰为２７３．５ｎｍ。     

STUDIES ON DANDELION YELLOW MOSAIC AND OTHER VIRUS DISEASES OF LETTUCE

The symptoms caused by dandelion yellow mosaic virus on cultivated lettuce, Lactuca serriola and L. virosa , are described and compared with those caused by lettuce mosaic virus. Lettuce is much more susceptible than dandelion to the yellow mosaic virus; no infections of dandelion were obtained by mechanical inoculation and only three by aphides, whereas infection of lettuce is regularly obtained by aphides and by inoculation provided an abrasive is used. Myzus ornatus, M. ascalonicus and Aulacorthum solani transmitted dandelion yellow mosaic virus but not lettuce mosaic virus, whereas Myzus persicae transmitted the latter but not the former. Nasonovia ribicola , the common lettuce aphis, transmitted neither. Aphides became infective only after feeding periods of some hours on the diseased plants and ceased to be infective within an hour of the infective feeding. Their efficiency as vectors was not increased by a preliminary starving period, as happens with Myzus persicae and lettuce mosaic virus. Lettuce mosaic virus was found in most samples of commercial seed, which explains its prevalence; no evidence was found for the seed-transmission of dandelion mosaic virus and it is doubtful if it occurs, for infected lettuce are so severely affected that they rarely set seed.
Cucumber mosaic virus was isolated from naturally infected lettuce.