Immune Reactivity following Poly I·Poly C Treatment in Mice

POLYINOSINIC-polycytidylic acid (poly I·poly C) and other synthetic double stranded RNAs are known to be potent inducers of interferon¹, to enhance humoral^2,3 and cellular^3,4 immune responses and to exert a protective action against viral¹ and bacterial infections⁵ and tumours⁶. In addition to these protective effects, however, deleterious characteristics such as pyrogenicity in rabbits⁷ and toxicity in other species⁸ have been described. We show here that poly I·poly C can also produce either enhancement or depression of the immune response to sheep red blood cells (SRBC) depending on the time of injection of the polyribonucleotides in relation to antigenic stimulation.     

Common Bean (Phaseolus vulgaris L.) Mutants Defective in Root Nodule Formation: II GENETIC ANALYSIS

Genetic analysis of crosses between two induced, ineffectivelynodulating mutants of common bean, NOD238 and NOD109, revealedthat their mutated nodulation phenotype is under the controlof the same locus in both mutants. The two mutants also resultedallelic for poor pod fertility, the other trait common to themutants. F₁ plants from crosses with their wild types nodulatedeffectively and had wild type pod fertility. Ineffective nodulationand poor pod fertility traits co-segregated in the F₂generationin which plants with the mutant nodulation and pod fertilityphenotypes represented 12.5% of the total population. Analysisin F₃confirmed that these plants were homozygous for both mutatedcharacters. The results indicated both mutant traits studiedare determined by a single recessive allele, named sym-2, whoseinheritance is negatively affected by its pleiotropic effecton pod fertility determining a deficit of ineffectively nodulatingcombinations. In an allelism test with the non-nodulating mutantof common bean NOD125 it was found that ineffective nodulationis controlled at a different locus and that the two loci arenot linked. Key words: Phaseolus valgaris, nitrogen fixation, nodulation mutants, genetics