文蛤副溶血弧菌病的研究

近年来,广西沿海在５—６月份常发生文蛤大批死亡现象,从死亡文蛤中分离到病原菌,经人工感染试验得到证实。病原菌为革兰氏阴性短杆菌（０．８－１．０×１．５－１．８μｍ）,具偏端生单鞭毛。在ＴＣＢＳ琼脂平板上培养２４ｈ后,形成蓝绿笠状菌落,菌落直径２－３ｍｍ,发酵葡萄糖产酸不产气,精氨酸－碱反应阴性,赖氨酸、鸟氨酸脱羧阳性,靛基质阳性。在温度１０－４２℃、ｐＨ值５－１１、盐度０．５－８１％的环境条件下都能生长。该菌具有较强的毒力。经系统生理生化特性鉴定和ＶＩＴＥＫ微生物自动分析仪鉴定,病原菌为副溶血弧菌（Ｖｉｂｒｉｏｐａｒａｈａｅｍｏｌｙｔｉｃｕ）。选择适当的养殖场地、做好蛤苗投放工作、掌握好放养密度、加强养成管理、加强环境监测预报是防治文蛤疾病流行的主要措施。     

文蛤弗尼斯弧菌病研究

由江苏南部沿海滩涂死亡文蛤中分离到一种革兰氏阴性杆菌,经系统生理生化特性鉴定为弗尼斯弧菌(Vibrio furnissii)。该菌能利用文蛤汤作为培养基,在25—37℃海水中大量繁殖,具有较强的毒力。用此菌感染健康文蛤,发病症状及死亡情况均与自然发病一致。我们认为江苏南部文蛤大批死亡与文蛤弗尼斯弧茵病流行有关,这在国内外尚未见报道。     

弗氏柠檬酸杆菌对河触致病性的研究

首次报道了弗氏柠檬酸杆菌对河蟹的病原性、并导致其病理变化,药对物该菌的敏感试验及生产中药物治疗效果。从垂死的病蟹肝胰脏中分离得到可疑病菌,经人工感染试验证实此菌导致健康蟹发病死亡。该菌可导致河触的肝胰腺、鳃等发生病理变化,最终引起败血症而死亡。通过16种药物对该菌的敏感试验,筛选出有效药物,应用于生产中取得了较好疗效。     

THE STABILITY OF BACTERIAL SUSPENSIONS : II. THE AGGLUTINATION OF THE BACILLUS OF RABBIT SEPTICEMIA AND OF BACILLUS TYPHOSUS BY ELECTROLYTES.

1. Measurements have been made of the potential and of the cohesive force at the surface of Bacillus typhosus and the bacillus of rabbit septicemia in solutions of various salts and acids. 2. Electrolytes in low concentration (0.01 N) affect primarily the potential, and in high concentration decrease the cohesive force. 3. As long as the cohesive force is not affected, agglutination occurs whenever the potential is reduced below about 15 millivolts. 4. When the cohesive force is decreased the critical potential is also decreased, and in concentrated salt solution no agglutination occurs even though there is no measurable potential.     

AN EXPERIMENTAL FIELD STUDY OF ANTHER-SMUT DISEASE OF SILENE ALBA CAUSED BY USTILAGO VIOLACEA: GENOTYPIC VARIATION AND DISEASE INCIDENCE

Twenty cloned genotypes of Silene alba differed greatly (0–100%) in the percentage of flowering plants that became diseased by the anther-smut fungus Ustilago violacea following natural spore dispersal in a two-year field experiment. Male genotypes with the highest percentage of disease had high rates of flower production; this trait may increase the probability of spore deposition on flowers, a common site of infection. Because of this relationship, male genotypes with the highest percentage of disease also produced the most healthy flowers in the two-year period. Flowering early in the season was also a predictor of high disease levels for male genotypes in the first year. Variation among female genotypes in disease levels was not correlated with either flower production or phenology, suggesting that the sexes differ in their interaction with the pathogen. Plants of both sexes that remained nonreproductive the first year but flowered the second year could become diseased due to infection of vegetative tissue. Disease levels of the genotypes following natural spore dispersal were not correlated with disease levels of the genotypes following inoculation of vegetative tissue. This discrepancy points out that the methodology used to investigate genetic variation in disease resistance may affect the results obtained.     

弗氏柠檬酸杆菌对河蟹致病性的研究

首次报道了弗氏柠檬酸杆菌对河蟹的病原性、并导致其病理变化,药物对该菌的敏感试验及生产中药物治疗效果.从垂死的病蟹肝胰脏中分离得到可疑病菌,经人工感染试验证实此菌导致健康蟹发病死亡.该菌可导致河蟹的肝胰腺、鳃等发生病理变化,最终引起败血症而死亡.通过16种药物对该菌的敏感试验,筛选出有效药物,应用于生产中取得了较好疗效.       

A DISEASE OF CHERRY LAUREL CAUSED BY TROCHILA LAUROCERASI (DESM.) FR

A leaf spot disease of cherry laurel is described. The infected areas eventually become occluded and fall out, leaving irregular holes in the foliage. The disease is caused by Trochila Laurocerasi (Desm.) Fr., the imperfect stage of which is proved to be Gloeosporium-phacidiellum Grove. Infection takes place on the young leaves, most commonly through wounds, and a moist atmosphere is essential for the development and spread of the disease. Control can be effected by spraying with colloidal sulphur during spring and early summer, and by cutting back the bushes only in the autumn, not at short intervals during the summer as is frequently the practice.
The writer wishes to acknowledge her indebtedness to Dr G. H. Pethybridge for valuable suggestions during the course of this work, also to Dr C. E. Foister for the photographs reproduced on PL XXXI.     

GENETIC EXCHANGE BETWEEN BACILLUS SUBTILIS AND BACILLUS LICHENIFORMIS: VARIABLE HYBRID STABILITY AND THE NATURE OF BACTERIAL SPECIES

Experiments employing both broth and soil cultures demonstrated the capacity for bidirectional genetic exchange between the eubacterial species Bacillus subtilis and Bacillus licheniformis. The process was studied using standard laboratory strains and wild isolates of these species. The genetic exchange in soil occurs spontaneously. The interspecific recombination involved markers for antibiotic resistance and for the use of specific carbon sources (API characters). Hybrids frequently had unstable phenotypes, i.e., lacked a consistent expression of foreign genes over repeated transfer and growth. This instability often involved a “correction” back toward the phenotype of one or the other of the parental species for many differentiating characters; the final phenotype was always that of the more probable or actually known recipient species. This “correction” process is reminiscent of phenomena associated with the instability of artificial fusion protoplasts or noncomplementing diploids of B. subtilis, as well as the merodiploids formed by intergeneric crosses with enteric bacteria. The hybrids observed here must also be diploid, in some manner, because they sequentially express traits of both parental species at rates well above the frequency of mutation. Among the unstable changes in hybrids of the wild strains there was a 3:1 bias in favor of “correction.” The dynamics of the hybridization process in soil are described. It appears that the hybrids are formed most rapidly following outgrowth from spores and during the early growth of parental vegetative cell populations. Later on, the hybrids are much less frequent in the soil cultures, suggesting that they are competitively inferior to the parental species. It is argued that the capacity for recombination found between B. subtilis and B. licheniformis could locally erase their distinctness, even though they possess only about 15% DNA sequence homology. Yet they remain distinct in the wild. The methods and results of these experiments prepare the way for detailed studies of the nature of species and species boundaries throughout the genus Bacillus.     

SEEDLING BLIGHT OF SUGAR-CANE-A NEW DISEASE CAUSED BY HELMINTHOSPORIUM SACCHARI BUTLER

The fungus Helminthosporium sacchari Butler, known to be the cause of eye spot, a common air-borne disease of sugar-cane leaves, is now shown to be the cause of an undescribed seed-borne disease of sugar-cane seedlings. It is therefore suggested that the disease should be renamed eye spot and seedling blight of sugarcane.
The symptoms of seedling blight are described, and the pathogenicity of the fungus to sugar-cane seedlings is confirmed. Incidence of seedling blight is shown to be markedly affected by the growing conditions, and disease-escape is common. The two most important factors predisposing seedlings to attack appear to be (i) the relative humidity of the atmosphere, and (ii) the occurrence of a check to the continuous growth of the seedlings.
With the discovery of the existence of seedling blight, eye spot assumes a particular significance in plant-breeding plots, because it may be responsible for the loss of sugar-cane seedlings, any one of which is potentially a desirable new variety.     

草鱼的一种急性细菌性传染病病原的分离鉴定及致病性研究

草鱼(Ctenopharyngodon idellus)的细菌性疾病是草鱼人工养殖过程中经常出现的疾病。文章对河南一草鱼养殖场2009年8月出现的暴发性细菌性传染病进行了研究。该渔场饲养的草鱼成鱼和鱼苗出现了体表溃烂、局部出血, 肠系膜充血、出血, 腹腔积水等症状, 并大量死亡。从濒死草鱼的内脏中分离到3株细菌, 经形态学、生理生化特性及16S rDNA序列分析, 鉴定为霍乱弧菌(Vibrio cholerae)、嗜水气单胞菌(Aeromonas hydrophila)和柱状黄杆菌(Flavobacterium columnare)。其中, 从患病鱼苗体内分离到霍乱弧菌; 从成鱼分离到嗜水气单胞菌和柱状黄杆菌。回归试验证明3株细菌均能使草鱼致死, 其中霍乱弧菌和嗜水气单胞菌对草鱼的半数致死量(LD50)分别是0.15104 cfu/g和0.96103 cfu/g。从草鱼中分离到致病性霍乱弧菌是首次报道。药敏试验表明, 在所试的17种抗生素中, 霍乱弧菌仅对利福平、左旋氧氟沙星、链霉素、奥复星、庆大霉素等5种抗生素敏感; 嗜水气单胞菌仅对菌必治、奥复星、庆大霉素等3种抗生素敏感; 而柱状黄杆菌则对其中的氨苄青霉素、利福平、左旋氧氟沙星等10种抗生素均敏感。