Influence of the Numbers of Rhizobium supplied on the Subsequent Nodulation of the Legume Host Plant

The effect of numbers of Rhizobium supplied on the subsequentnumbers of nodules formed was tested with Phaseolus radiatusvar. aurea in water culture. Nine weeks after inoculation plants supplied with from 88,700to 887,000 bacteria per c.c. of culture solution bore significantlymore nodules than those given from 89 to 887 per c.c. An inoculumof 44,350 per c.c. produced intermediate numbers of nodules. One week after inoculation, the percentage of curled and ofinfected root-hairs on the seedlings was roughly proportionalto the logarithm of the bacterial numbers supplied, while thenumbers of nodules produced at this stage already showed a significantdifference between extreme doses of inoculum. Nine weeks after inoculation the final nodule numbers were relatedto the percentages of curled and of infected root-hairs afterone week. The final nodule numbers are related to the growth of the rootsystem since the final number of nodules per gramme of rootis independent of the initial dose of inoculum, the effect ofwhich was mainly to cause an increase in root growth.     

A SIMPLIFIED METHOD of COLONY HYBRIDIZATION USING RADIOLABELED PROBES IN SEALED PETRI DISHES

A simplified colony hybridization procedure was developed using sealed disposable plastic petri dishes in place of sealed plastic bags. Prior to hybridization, the dishes were sealed with successive layers of parafilm, plastic wrap and aluminum foil to prevent evaporation of the solution. This self-contained procedure eliminates some of the technical problems such as spilling of radioactive materials, leakage of solution, sealing of plastic bags and the formation of air bubbles. Therefore, this method allows for safer and easier handling of radioactive materials during hybridization procedures.     

A METHOD FOR ISOLATION OF CHROMOSOMAL AND PLASMID DNA FROM YERSINIA ENTEROCOLITICA FOR SIMULTANEOUS AMPLIFICATION BY POLYMERASE CHAIN REACTION: A POSSIBLE MODEL FOR OTHER BACTERIA

A commercial DNA isolation kit was evaluated for simultaneous isolation of chromosomal and plasmid DNA from Yersina enterocolitica for polymerase chain reaction amplification. The genomic and plasmid DNA samples obtained by use of the kit were suitable for use in polymerase chain reactions both individually and in multiplex reactions. The results obtained by the use of the kit suggest that this kit may be applied to isolate both genomic and plasmid DNA from other microorganisms for polymerase chain reaction amplification.     

Neoglycoproteins as Carriers for Receptor-Mediated Drug Targeting in the Treatment of Experimental Visceral Leishmaniasis

ABSTRACT. Methotrexate (MTX) coupled to mannosyl bovine serum albumin (BSA) was taken up efficiently through the mannosyl receptors present on macrophages. Binding experiments indicate that conjugation does not decrease the affinity of the neoglycoprotein for its cell surface receptor. The drug conjugate eliminated intracellular amastigotes of Leishmania donovani in mouse peritoneal macrophages about 100 times more efficiently than free drug on the basis of 50% inhibitory dose. Inhibitory effect of the conjugate was directly proportional to the density of sugar on the neoglycoprotein carrier. Colchicine and monensin, inhibitors of receptor-mediated endocytosis, can prevent the leishmanicidal effect of the conjugate. Antileishmanial effect of the conjugate can be competitively inhibited by mannose-BSA and mannan. In a murine model of experimental visceral leishmaniasis the drug conjugate reduced the spleen parasite burden by more than 85% in a 30-day model whereas the same concentration of free drug caused little effect. These results indicate that MTX-neoglycoprotein conjugate binds specifically to macrophages, and is internalized and degraded in lysosomes releasing the active drug to act on Leishmania parasites. These results also represent the potential for a general approach to intracellular targeting of clinical agents for macrophage-associated disorders.     

A METHOD FOR the DETERMINATION of STRANDEDNESS of DNA FRAGMENTS CLONED IN PHAGE M13

Recombinant M13Hol phage containing Eco R1 restriction endonuclease fragments B, E, and F of adenovirus type 2 (Ad2) DNA were constructed by cloning into the unique Eco R1 site of the replicative form of the phage M13Hol176 DNA. Polarity of the adenovirus inserts in recombinant molecules was deduced by the following procedures: Viral DNA fragments obtained from Ad2 DNA molecules were purified, denatured, and subjected to electrophoresis. the separated DNA strands were transferred from agarose to nitrocellulose by the Southern procedure and hybridized with radioactive 3'-end labeled Hae III fragments of the recombinant phage DNAs. This procedure provided a rapid test for assaying strandedness of the cloned fragments.