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1.
报道了一个黏菌新变种,小筛菌大孢变种Cribraria microcarpa var.megaspora nov.var.,获得于湿室培养的采自云南大围山国家级自然保护区的柳杉Cryptomeria fortunei树皮上,其特征是比原变种具有明显较大的孢子。这里描述和图示了这个新变种,模式标本保存于南京师范大学微生物菌种保藏中心。  相似文献   

2.
Carcasses of mosquito larvae killed by Bacillus thuringiensis var. israelensis allow its complete growth cycle (germination, vegetative growth, and sporulation), thus becoming toxic themselves to scavenging larvae. In this study, we demonstrate that the bacterium is capable of inducing death of Aedes aegypti pupae and of recycling in the resulting carcasses. B. thuringiensis var. israelensis-killed pupae were obtained by treating 40-hr-old synchronized fourth instar larvae with a low dose of spores (8000/ml). The fraction of dead pupae was reduced by higher or lower spore concentrations as well as by treating younger or older larval populations (both fourth instar): Increased proportions of dead larvae were obtained at higher concentration or by earlier treatment, whereas lower concentrations or later treatment resulted in more living pupae. Multiplication of B. thuringiensis var. israelensis is shown to occur in the carcasses of dead pupae. The number of spores in each pupal carcass followed a similar kinetic as in larval carcasses, but the final yield was about 10-fold higher, apparently reflecting the difference in dry weight between the two mosquito developmental stages (426 micrograms vs 83 micrograms, respectively). The specific larvicidal activity in a homogenized dead pupa was similar to that of B. thuringiensis var. israelensis powder, LC50 of about 600 spores/ml.  相似文献   

3.
A method based on the tyndallization procedure is described for isolation of Bacillus popilliae var. rhopaea spores from the soil. A soil suspension is diluted with a germinating medium, which promotes the germination of most spores except B. popilliae var. rhopaea, and is treated with a series of seven heat shocks (70°C for 20 min) at hourly intervals. This treatment reduced the number of contaminant spores by over 95%. The suspension is then plated out onto “J” medium which allows the germination and growth of all surviving spores including the milky disease spores. The plates are incubated anaerobically at 28°C for 7 days before the characteristic small transparent colonies of B. popilliae var. rhopaea are counted. In testing the method it was revealed that about 15% of the milky disease spores in the soil produced visible colonies, and that a spore concentration of over 1.2 × 105 spores/g dry wt of soil could be quantified. This concentration of spores produces only 3% infection in Rhopaea verreauxi larvae. The method may be applicable to other varieties of B. popilliae which will grow on “J” medium.  相似文献   

4.
The larvicidal activity of Bacillus thuringiensis var. israelensis against mosquitoes and the blackfly is included in parasporal crystalline bodies which are produced during sporulation. Following ingestion, the crystals are solubilized in the larval midgut and induce death within a short time; the spores germinate in the dead larvae and complete a growth cycle. The fate of the spores in surviving live larvae was elucidated by using a nonlarvicidal B. thuringiensis var. israelensis mutant. When introduced as the only food source, spores of this mutant support development to the adult stage of newly hatched Aedes aegypti larvae at a rate directly related to spore concentration. The conclusion that spores of B. thuringiensis var. israelensis are digested in the larval gut was substantiated by following the incorporation of [35S]methionine-labeled spores into larval tissues.  相似文献   

5.
Thalictrum fortunei S. Moore var. bulbiliferum B. Chen & X. J. Tian, a new variety of the Ranunculaceae from Jurong County, Jiangsu Province, China, is described and illustrated. It is different from the typical variety, var. fortunei, by having bulbils in axils of most of the cauline leaves after anthesis.  相似文献   

6.
记载了中国江苏宝华山唐松草属一新变种——珠芽华东唐松草Thalictrum fortunei S. Moore var. bulbiliferum B. Chen &; X. J. Tian。该变种在花谢之后在大部分叶腋处形成一枚直径3-10 mm的珠芽,明显区别于原变种。  相似文献   

7.
Magnolia denudata var. glabrata Y. L. Wang et S. Z. Zhang var. nov. is described and illustrated from Hunan, China. The variety occurs mainly in semi‐evergreen forest of south Hunan at altitudes between 700 and 1260 m a.s.l. It differs from M. denudata var. denudata by its green and glabrous twigs and leaves which are glabrous above and have some white pubescence underneath. With its white flowers consisting of mostly 9 tepals, it differs from M. sprengeri Pamp. which mainly has 12 tepals in various shades of red/pink to white. The new variety is rare and considered endangered due to habitat destruction.  相似文献   

8.
毛节缬草的粉末鉴别   总被引:1,自引:0,他引:1  
目的:研究黑龙江省毛节缬草Valeriana alternifolia Bunge var.stolonifera Bar.et Skv.的粉末鉴别特征.方法:性状鉴别、显微鉴别.结论:毛节缬草根、根茎、茎和叶的粉末均有明显的鉴别特征,可作为鉴别毛节缬草的依据.  相似文献   

9.
The antigenic and toxic properties of the crystalline proteins from two varieties of B. thuringiensis (var. galleriae and var. insectus) were studied. Methods of double diffusion in agar and two-dimensional disc immunoelectrophoresis revealed four antigens in the crystalline protein from var. galleriae and three in that from var. insectus. A definite correlation was found between the toxicity of the crystalline protein and its capacity to interact with antiserum in a precipitation reaction in agar. It was established that the total protein content cannot be used as the criterion for an evaluation of the activity of preparations from B. thuringiensis. Immunodiffusion methods are recommended for an evaluation of the quality of these preparations.  相似文献   

10.
11.
Cryptococcus neoformans is a human fungal pathogen that exists as three distinct varieties or sibling species: the predominantly opportunistic pathogens C. neoformans var. neoformans (serotype D) and C. neoformans var. grubii (serotype A) and the primary pathogen C. neoformans var. gattii (serotypes B and C). While serotypes A and D are cosmopolitan, serotypes B and C are typically restricted to tropical regions. However, serotype B isolates of C. neoformans var. gattii have recently caused an outbreak on Vancouver Island in Canada, highlighting the threat of this fungus and its capacity to infect immunocompetent individuals. Here we report a large-scale analysis of the mating abilities of serotype B and C isolates from diverse sources and identify unusual strains that mate robustly and are suitable for further genetic analysis. Unlike most isolates, which are of both the a and α mating types but are predominantly sterile, the majority of the Vancouver outbreak strains are exclusively of the α mating type and the majority are fertile. In an effort to enhance mating of these isolates, we identified and disrupted the CRG1 gene encoding the GTPase-activating protein involved in attenuating pheromone response. crg1 mutations dramatically increased mating efficiency and enabled mating with otherwise sterile isolates. Our studies provide a genetic and molecular foundation for further studies of this primary pathogen and reveal that the Vancouver Island outbreak may be attributable to a recent recombination event.  相似文献   

12.
Genkal  S. I.  Kiss  K. T. 《Hydrobiologia》1993,269(1):39-47
Cyclotella atomus collected from different rivers, reservoirs and lakes shows considerable morphological variability. On the basis of electronmicroscopic (EM) study, we propose Cyclotella atomus var. gracilis Genkal et Kiss as a new variety of this species. Cyclotella atomus var. atomus has short and long radial striae, which are irregularly arranged on the same valve, and the alveolar chambers are not clearly divided from the central, hyaline part of the valve face. In addition to the described basic form, several specimens with other features have also been found and are thought to belong to an undescribed variety. The striae of the new variety are equal in length, and the alveolar chambers are clearly divided from the hyaline central area of the valve face by a curved structure.There are EM micrographs on Cyclotella atomus var. gracilis under different names in different papers. The new variety has several characteristics also found in other species, e.g. Cyclotella caspia Grun., or C. meneghiniana Kütz.  相似文献   

13.
A hot-air sterilizer capable of exposing airborne microorganisms to elevated temperatures with an almost instantaneous heating time was developed and evaluated. With this apparatus, aerosolized Bacillus subtilis var. niger spores were killed in about 0.02 sec when exposed to temperatures above 260 C. This is about 500 times faster than killing times reported by others. Extrapolation and comparison of data on the time and temperature required to klll B. subtilis var. niger spores on surfaces show that approximately the same killing time is required as is necessary for spores in air, if corrections are made for the heating time of the surface.  相似文献   

14.
报道了四川德昌县发现的山茶科(Theaceae)木荷属(Schima Reinw.)一新变种--扁果银木荷(Schima argentea Pritz.var.platycarpa Q.Luo).新变种花瓣长2~2.6 cm,宽1.6~2.2cm,内面基部被柔毛,蒴果扁球形,直径1.7~2.1cm,高1~1.3cm等特...  相似文献   

15.
Viability, antibiotic properties and variation of 4 variants of Bac. brevis var. G.-B. were studied after lyophilization and storage for a year in the lyophilized state. It was shown that the spores and vegetative cells of S and P- variants not synthesizing gramicidin S were somewhat more stable than the spores and cells of R and P+ variants producing the antibiotic. The latter dissociated by 10 per cent towards the cells producing and not producing gramicidin. The developmental rate of the lyophilized vegetative cells was higher than that of the lyophilized spores. Under analogous cultivation conditions they produced higher amounts of the biomass and antibiotic. The lyophilization method described may be recommended for the maintenance of viability and stability of the spores and vegetative cells of Bacillus brevis var. G.-B. producing gramicidin S.  相似文献   

16.
Dry-heat sterilization of planetary lander capsules requires a knowledge of the thermal resistivity of microorganisms in the environment to which they will be subjected during sterilization of the space hardware. The dry-heat resistance of Bacillus subtilis var. niger spores on various lander capsule materials was determined at 125 C. Eight surface materials were evaluated, including a reference material, stainless steel. Survivor curves were computed, and decimal reduction times (D values) were obtained by a linear regression analysis. In four tests on stainless steel, the average value of D at 125 C was 17.07 min. The D values for the other seven materials tested ranged from 18.64 min on magnesium surfaces to 20.83 min on conversion-coated magnesium. Of the materials evaluated, the results indicate that there is only a significant difference in the thermal resistance of B. subtilis var. niger spores on conversion-coated magnesium and conversion-coated aluminum from that on the reference material, stainless steel. The differences in D values for all the test surfaces may be the result of variations in test procedures rather than the effect of the surfaces on the thermal resistivity of the spores.  相似文献   

17.
广西唇柱苣苔属(苦苣苔科)一新变种——光华唇柱苣苔   总被引:1,自引:0,他引:1  
记载了广西苦苣苔科Gesneriaceae一新变种——光华唇柱苣苔Chirita tribracteata、W.T.Wang var.zhuana Z.Y.Li,Q.Xing&Y.B.Li。该变种与原变种不同在于叶大而厚,边缘具圆齿或牙齿,叶柄具宽翅,苞片宽倒卵形或倒披针形,有锯齿,花冠淡紫色,喉部具黄色纵纹。  相似文献   

18.
A new variety of Mallomonas corymbosa is described from a pond in Nahuel-Huapi National Park (Argentina): M. corymbosa var. interrupt nov. var. Fine structure of scales and bristles has been studied by scanning and transmission electron microscopy.  相似文献   

19.
对苞萱草的核型研究   总被引:2,自引:0,他引:2  
孔红   《广西植物》1998,18(4):368-370
本文报道用光学显微镜观察对苞萱草Hemerocalisfulva(L.)L.var.op positibracteataH.KongetC.J.Wang,var.nov.的染色体,按全国第一次植物染色体学术讨论会建议的标准进行核型分析。研究结果表明,对苞萱草体细胞染色体数目2n=22,核型公式k(2n)=22=12m+6sm+4st,属于Stebbins核型的2B型。甘肃萱草属植物的核型可分为两大类群,对苞萱草的核型属于第二类群。对苞萱草与萱草H.fulva(L.)L.的核型较接近,为新变种的确立提供了细胞学方面的依据。  相似文献   

20.
报道并描述了罂粟科一新变种--重瓣野罂粟(Papaver nudicaule var.pleiopetalum J.C.Shao,var.nov.).该变种与野罂粟的主要区别是具有重瓣花.  相似文献   

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