BIOLOGICAL TECHNIQUES FOR THE EVALUATION OF FUNGICIDES

The effectiveness of fungicides for the control of Plasmodtophora brassicae Woron. in pot tests under controlled conditions is influenced by spore load, duration of storage of spores prior to inoculation, time of year and temperature. Many fungicides are less effective in soil which has been heavily treated with calcium hydroxide than in unlimed soil or in soil treated with calcium carbonate. In general, fungicides are less efficient when very heavy attacks of the disease occur. If experiments are made under comparable conditions consistent conclusions can be obtained.
A schedule of testing is recommended, and it is suggested that fungicides found to be satisfactory in a preliminary test should be subjected to a detailed test. The proposed method of evaluation of a fungicide is to compare its efficacy with that of a standard treatment under comparable conditions. For comparative purposes the efficiency of a fungicide is measured by the percentage number of diseased plants occurring in treated soil and also by the disease index.     

A DIRECT-SPRAY TECHNIQUE FOR THE BIOLOGICAL EVALUATION OF PYRETHRUM-IN-OIL INSECTICIDES FOR USE AGAINST STORED PRODUCT INSECTS IN WAREHOUSES

A direct-spray technique for the biological assay of pyrethrins in Shell oil P31 is described, together with the experiments leading to its adoption. The technique is such that film effects are reduced to the minimum practicable, but it is otherwise as similar as possible to the film technique described by Parkin & Green (1943). Methods for statistical analysis of the results are discussed. For the biological assay of pyrethrins in Shell oil P31, the direct-spray method is slightly superior to Parkin & Green's film method, but both techniques should have their uses in general experimental work.     

A FIELD TECHNIQUE FOR RECORDING THE ACTIVITY OF LIMPETS

A field technique for recording both temporal and spatial parametersof activity in limpets was tested on a Tyrrhenian populationof Patella rustica Linnaeus which shows definite homing behaviour.Timing of foraging excursions was recorded using reed switchesactivated by a magnet glued to the shell apex. The ‘lsquo;athome-away’ status of each animal was continuously screenedthroughout one month by interfacing the sensors with a computer.Moreover, individual excursions were minutely reconstructedby using a moto-graphic technique which combined LED-tracking(nocturnal activity) and instantaneous photography (daytimemovements). An original wave-meter was designed to monitor thesea-status during the study period. The quality of the temporaland spatial data obtained with this technique is evaluated,and further improvements of the technique are discussed. (Received 24 October 1989; accepted 25 January 1990)     

A NEPHELOMETRIC METHOD FOR THE EVALUATION OF BACTERIOSTATIC ACTIVITY

SUMMARY: Different suspensions of Bacterium coli in distilled water, prepared by a routine technique and adjusted nephelometrically with reference to a ground glass screen, showed no significant difference in their viable counts at the 5% level.
In a study of the inhibition by phenol of cultures grown in peptone water from inocula of such suspensions the regression line obtained by plotting the probit of the percentage inhibition against the logarithm of the concentration was rectilinear. From this the concentration needed for 95% inhibition was calculated.     

THE DEVELOPMENT OF A COMPARATIVE METHOD FOR THE EVALUATION OF THE MOTH-PROOFNESS OF WOOL SERGE

Existing test methods for the moth-proofness of wool were compared in inter-laboratory experiments and found to be lacking in accuracy and agreement between laboratories.
Several factors influencing the usefulness of such a test method were investigated, and it was found that a considerable gain in accuracy could be reached if weight loss due to larval attack on test samples was referred to weight loss obtained with a standard wool serge impregnated with a standard moth-proofing substance. Apart from this principle, improvements in the general testing procedure, including the number of test samples and test animals used, the definition of weight loss and the introduction of strict randomization procedures proved to be valuable.
As a provisional reference standard, wool serge impregnated with dinitro-α-naphthol was adopted. A tolerance level for the moth-proofness of wool serge was laid down.     

竹提取物对淡色库蚊Culexpipienspallens幼虫的活性评价(英文)

报道了竹提取物对淡色库蚊Culex pipiens pallens幼虫的毒杀作用。研究结果表明,巨县苦竹(Pleioblastus juxianensis)、白纹短穗竹(Brachystachyum albostriatum)、灰水竹(Phyllostachysplatyglossa)和苦竹(Pleioblastus amarus)提取物对淡色库蚊幼虫的24h致死中浓度(LC50)分别为30.65mg／L、53.94 mg／L、41.21mg／L、54.49mg／L。巨县苦竹索氏抽提物对淡色库蚊幼虫的毒杀作用明显强于间歇振荡提取物,前者对淡色库蚊幼虫的LC50为30.65 mg／L,95％置信限27.12~34.63 mg／L;后者的LC50为48.34 mg／L,95％置信限为40.37~59.62 mg／L。巨县苦竹乙醚浸提物对淡色库蚊幼虫的毒杀作用效果显著,125mg／L浓度时12h校正死亡率为56.67％,24h后达92.90％;石油醚浸提物及甲醇浸提物对淡色库蚊幼虫的毒杀作用则不明显, 24h校正死亡率均不超过40％。研究结果将有助于综合利用竹类资源,开发新型环境友好农药。     

EVALUATION OF EXTRACTS FROM BAMBOO FOR BIOLOGICAL ACTIVITY AGAINST CULEX PIPIENS PALLENS

The extracts from 7 species of bamboo were tested for larvicidal activity against Culex pipiens pallens. At the tested concentration, the extracts of selected bamboo had different degree of toxic effects on the fourth instar larvae of Culex pipiens pallens. Among them,the extracts of Pleioblastus juxianensis, Brachystachyum albostriatum, Phyllostachys platyglossa and Pleioblastus amarus were found to be effective with LC50values at 24h of 30.65mg/L,53.94mg/L, 41.21 mg/L and 54.49 mg/L respectively, against Culex pipiens pallens larvae. The extract of Pleioblastus juxianensis by Soxhlet method showed stronger activity than the extract obtained by interval-shaking, the LC50 of which were 30.65 mg/L and 48.34 mg/L, respectively.The diethyl ether extract of Pleioblastus juxianensis exhibited better larvicidal activity than the methanol extract and the petroleum ether extract. The results would help to provide the basis for the study of environment acceptable pesticide for mosquito control, and also help to comprehensively utilize the source of bamboo.     

A NEW INCUBATION TECHNIQUE FOR THE STUDY OF SYNAPTOSOMAL TRANSPORT

A simple, inexpensive method is described for the incubation and study of transport in synaptosomes. This method avoids the many potential sources of error inherent in the methods currently in use. The transport of two sugars and two amino acids has been studied, using this system, and the resulting data is compared to similar studies already published by others. A steady-state was achieved and maintained for 60 min independent of tissue concentration, except in the case of γ-aminobutyric acid. An analysis of the entry kinetics of 2-deoxy-d -glucose has been performed, the results indicating that the present method offers the advantage of substantially increasing oxygenation and hence, efficiency of the uptake. Using α-aminoisobutyric acid, analysis of substrate flux within the system was performed, illustrating the utility of the method. The specific advantages offered by the technique over other methods in use are discussed. It is concluded that adequate oxygenation of the synaptosome during study is essential to reliable results and can easily be achieved by means of the methodology described in this report.     

A TECHNIQUE FOR THE ANALYSIS OF EPISTATIC GENE ACTION II. THE APPLICATION OF THE METHOD

With a method based on probability of phenotypic ratios being produced by crosses involving two pairs of interacting genes, data from genetic studies of Impatiens Sultana Hook. f. (Balsaminaceae) were analysed. Nine genes postulated to control floral color are: P, purple; I and W, white; R, red; O, orange; F, fuchsia; D, red; E, red; S, salmon. Epistatic action was evaluated, but progeny counts were too small for linkage to be determined.     

A TECHNIQUE FOR THE ANALYSIS OF EPISTATIC GENE ACTION I. THE METHOD OF ANALYSIS

The thirty-two possible genic crosses involving two pairs of nonlinked genes were simulated. The anticipated progeny of each cross was analyzed according to each of the seven basic types of epistatic action. A key was devised to facilitate the recognition of genic action since most phenotypic progeny ratios are produced exclusively either by phenotypically similar parents or phenotypically dissimilar parents. Only ratios of 3:1, 2:1, and 1:1 can be produced by both types of parents.     

A LIGHT-SCATTERING TECHNIQUE FOR THE STUDY OF THE PERMEABILITY OF RAT BRAIN SYNAPTOSOMES IN VITRO

Abstract— (1) Swelling of synaptosomes was measured spectrophotometrically by recording changes in extinction at 520 nm.
(2) Synaptosomes behaved as osmometers in NaCl solutions. When the tonicity of the medium was changed, synaptosome volume changed in accordance with Boyle and van't Hoff's Law. These changes were reversed on restoring the tonicity of the medium.
(3) The rate at which a solute entered the synaptosome was determined from the rate of swelling in the presence of that solute. Permeability of synaptosomes to non-electrolytes was in the order glucose ≪ glycerol < thiourea = formamide < propylene glycol = dimethylsulphoxide.
(4) Synaptosomes were freely permeable to ammonium and acetate ions and impermeable to Ca²⁺, Mg²⁺, PO₄²⁻, SO₄²⁻ and oxalate ions.