Effect of some soybean and bean phytoalexins and related isoflavonoids on growth of Candida albicans.
The influence of a series of related isoflavonoids on growth of the zoopathogenic yeast, Candida albicans, in liquid media was studied. The order of effectiveness was identical with that previously found for a range of phytopathogenic fungi. Minimum inhibitory concentration of phaseollinisoflavan, the most active test compound, was 250 microM for 3 days after inoculation. However, C. albicans resumed growth thereafter. Phaseollinisoflavan, 500 microM, did not inhibit but only delayed growth of the yeast. Tolerance of C. albicans to phaseollin and phaseollinisoflavan was based on nondegradative mechanism(s), while tolerance to glyceollin appeared to be based on detoxification.
Differential sensitivity of Phytophthora megasperma f.sp. glycinea isolates to glyceollin isomers
Abstract Glyceollin isomers I, II and III were extracted from soybean cotyledons (cv. Harosoy 63) inoculated with Phytophthora megasperma f.sp. glycinea race 1, and separated and purified by column, high performance and thin layer chromatography and quantitated by spectrophotometry. The extinction coefficient of glyceollin I was 10 800, that of glyceollin II and III conformed to published values. Glyceollin I (ED50 approx. 33 μg ml−1) was almost twice as inhibitory as glyceollin II and III to growth of P. megasperma f.sp. glycinea race 1 on V8 juice agar. All three isomers were less active in soybean hypocotyl extract agar. Glyceollin II (ED50 7 μg ml−1) was the most active against zoospore germination, and caused zoospores to burst; ED50 values for glyceollin I and III were 12·2 and 13·9 μg ml−1 respectively. Three isolates (1·1, 1·2, 1·3) were obtained from sectors in colonies on agar medium amended with glyceollin I, II or III respectively. Isolates 1·1 and 1·3 grew more rapidly on medium amended with glyceollin I, III or a natural glyceollin mixture than did wild type P. megasperma fsp. glycinea race I. All isolates and wild type had similar growth rates on medium amended with glyceollin II. The isolates did not lose their tolerance when grown on control medium and are presumably genetically controlled variants. Tolerance of glyceollin did not increase the aggressiveness of the isolates on soybeans.
Hedy: A Gradual Language for Programming Education
One of the aspects of programming that learners often struggle with is the syntax of programming languages: remembering the right commands to use and combining those into a working program. Prior research demonstrated that students submit source code with syntax errors in 73% of cases and even the best students do so in 50% of cases. An analysis of 37 million compilations by 250.000 students found that the most common error was a syntax error, which occurred in almost 800.000 compilations. It was also found that Java and Perl are not easier to understand than a programming language with randomly generated keywords, stressing the difficulties that novices face in understanding syntax. This paper presents Hedy: a new way of teaching the syntax of a programming language to novices, inspired by educational methods by which punctuation is taught to children. Hedy starts as a simple programming language without any syntactic elements such as brackets, colons or indentation. The rules slowly and gradually change until the novices are programming in Python. Hedy is evaluated on 9714 programs.