Moderately Susceptible Research Articles

Pathochemical studies of cowpea, infected with Xanthomonas campestris pv. vignicola, and the role of leaf amino acids in evoking susceptible and resistant responses

Summary Summary The disease index of susceptible cowpea cultivars “Pusa Phalguni”, “Pusa Dofasli”, and “24/8-2 Assam” ranged between 67–70%, 15 d after infection of Xanthomonas campestris pv. vignicola . In the moderately susceptible “Pusa Barsati” and “Cowpea 9805” it was only 40 %. In the resistant cultivar “Red seeded” the symptoms were not at all exposed. The size and composition of the amino acid pool of the bacterium-inoculated leaf tissues varied with days of host-pathogen incubation and was specific and distinct for the above three categories of leaf tissues. In the suscepts and moderate suscepts the development of disease was sustained through post-infectional utilization of serine and β -alanine and high to moderate levels of early build up or constant and continued availability of leucine/isoleucine, phenylalanine, tyrosine, dl-alanine, dl-threonine, glycine, glutamic acid, asparagine, and aspartic acid in the infected tissues. However, in the moderately susceptible cv. a lesser degree of disease reaction was conjured through a minor level use-up of homoserine and glutamine. The resistant response in the variety “Red seeded” was, on the other hand, maintained through a vigorous shake-up in the amino acid pool, due to rapid and greater loss of homoserine, histidine, and arginine and a minor level of post-inoculative use up of glutamine, asparagine, glutamic acid, aspartic acid, glycine and tyrosine. These amino compounds, specially homoserine, histidine, and arginine, through their utilization as bactericidal substance, offered resistance in them.

Combination Effect of Cefmenoxime with Four Aminoglycosides on Enterobacteriaceae Susceptible and Moderately Susceptible to this New Cephalosporin

The inhibitory combination effect of cefmenoxime with gentamicin, tobramycin, netilmicin and amikacin against 148 Enterobacteriaceae was compared using the checkerboard agar dilution technique. On average 41% of cefmenoxime-moderately susceptible (MIC between 2 and 32 micrograms/ml) or cefmenoxime-resistant (MIC greater than 32 micrograms/ml) strains were inhibited by synergistic, and 23,5% by partial synergistic cefmenoxime-aminoglycosides combinations. Against cefmenoxime-susceptible strains, these rates of synergy or partial synergy were twofold lower, but only one isolate was not susceptible to these combinations. The amikacin-cefmenoxime interaction was the most performant.

Selectivity Mechanisms for Foliar Applications of Diclofop-methyl. II. Metabolism

The fate of foliarly applied14C diclofop-methyl {methyl 2-[4-(2,3-dichlorophenoxy)phenoxy] propanoate} was determined in intact plants of barnyardgrass [Echinochloa crus-galli(L.) Beauv.], a susceptible (S) grass; proso millet (Panicum miliaceumL.), a moderately susceptible (MS) grass; longspine sandbur [Cenchrus longispinus(Hack.) Fern.], a tolerant (T) grass; soybean [Glycine max(L.) Merr. ‘Hark’], and cucumber (Cucumis sativusL. ‘Green Star’), both T broadleaf plants, 1,3, and 5 days after treatment (DAT). Diclofop-methyl accounted for 94% of the radioactivity washed from the leaf surfaces of all species. Plant extracts contained diclofop-methyl, diclofop, and water-soluble conjugates. Barnyardgrass (S), proso millet (MS), and soybean (T) had 75, 68, and 66% of the extracted radioactivity as diclofop and diclofop-methyl. Longspine sandbur (T) and cucumber (T) had 71 and 84% of the extracted radioactivity as water-soluble conjugates. Acid hydrolysis of the water-soluble conjugates yielded 84 and 71% diclofop in barnyardgrass (S) and proso millet (MS). Cucumber (T), soybean (T), and longspine sandbur (T) had 43, 23, and 25% ring-OH diclofop. Alkaline hydrolysis of the non-extracted plant residue yielded diclofop as the major component in all species.

METHODS OF ASSAYING MOTION SICKNESS PREVENTIVES ON DOGS

The details of assay methods used since 1942 to test the effectiveness of motion sickness preventives in dogs are described.Animals first were classified according to their susceptibility to motion. Over a three year period dogs of moderate or marked susceptibility show little variation in the response to swinging or to treatment. Dogs of low susceptibility may become adapted to motion and be effectively treated by reduced dosage when used repeatedly.All dogs were treated using V-12 ethyl-β-methylallylthiobarbituric acid as a standard. Complete protection followed oral doses ranging from 1.25 to 30 mgm./kgm. and no untoward side effects were produced. Dogs of lowest susceptibility were most readily protected—by doses up to 5 mgm./kgm. Moderately susceptible animals required up to 15 mgm./kgm. and markedly susceptible ones more than this dose.Comparative assays with two other barbiturates showed that the results were not consistent when tests were made on groups of dogs of different susceptibility. V-12 was relatively more effective when tested on dogs of greatest susceptibility. Assays on dogs of low susceptibility that are readily treated are probably of questionable accuracy.Reducing the degree of swinging by one-half allowed the dogs to be effectively treated by one-fourth of the former dosage. The relative difference in potency between V-12 and another barbiturate was reduced by the change in magnitude of the swinging.The size and amplitude of the swing has a marked influence on quantitative assays. The smaller the degree of motion, the greater the apparent potency of a drug. Individual susceptibility to motion of the dogs is also a factor in obtaining comparable results. The greater the susceptibility, the more accurate the determination and comparison. Such factors will markedly limit comparisons of results obtained by different workers.