The developmental pattern of homologous and heterologous tRNA methylation in rat brain differential effect of spermidine

Using S -adenosyl- L -[Me- 14 C] methionine, rat cerebral cortex methyltransferase activity was determined during the early postnatal period in the absence of added Escherichia coli tRNA and in its presence. [Me- 14 C] tRNA was purified from both systems and its [Me- 14 C] base composition determined. The endogenous formation of [Me- 14 C] tRNA (homologous tRNA methylation) was totally abolished in the presence of 2.5 mM spermidine, whereas E. coli B tRNA methylation (heterologous methylation) was markedly stimulated. Only [Me- 14 C] 1-methyl guanine and [Me- 14 C] N 2 -methyl guanine were formed by homologous methylation, there being an inverse shift in their relative proportions with age. Heterologous tRNA methylation led, additionally, to the formation of [Me- 14 C] N 2 2 -dimethyl guanine, 5-methyl cytosine, 1-methyl adenine, 5-methyl uracil, 2-methyl adenine, and 1-methyl hypoxanthine. A comparison of heterologous tRNA methylation between the whole brain cortex (containing nerve and glial cells) and bulk-isolated nerve cell bodies revealed markedly lower proportions of [Me- 14 C] N 2 -methyl and N 2 2 -dimethyl guanine and significantly higher proportions of [Me- 14 C] 1-methyl adenine in the neurons. The present findings suggest (1) that homologous tRNA methylation may provide developing brain cells with continuously changing populations of tRNA and (2) that neurons are enriched in adenine residue-specific tRNA methyltransferases that are highly sensitive to spermidine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45399/1/11064_2004_Article_BF00966229.pd

Seroprevalence for brucellosis and leptospirosis in dogs from Belém and Castanhal, State of Pará, Brazil

Brucellosis and leptospirosis are widely spread bacterial infections and dogs are the most important source of infection and reservoir for diseases. Dogs can disseminate the agents in the environment and transmit them to humans and/or other animals. The objective of this study was assess the occurrence of reactive to antibodies anti-Leptospira spp., Brucella canis and B. abortus in Belém and Castanhal, State of Pará, Amazon, Brazil. A total of 156 samples were randomly collected in the city of Belém and 158 samples in Castanhal. The anti-B. canis antibodies research was performed by Agar Gel Immunodiffusion (AGID) with and without 2-mercaptoethanol serum treatment (AGID-2ME). To assess the anti-B. abortus antibodies, the technique of Fast Seroagglutination with buffered acidified plate antigen (BAPAT) was used. For anti-Leptospira spp. antibodies research, the Microscopic Agglutination Technique (MAT) was used. No animal reacted to Brucella abortus and one animal was reactive to B. canis at the AGID, but it was negative to the AGID-2ME test. Seventeen percent of dogs (47/274) presented anti-Leptospira spp. antibodies, with prevalence of serovar Canicola. The dogs from Belém and Castanhal are not source of infection for B. abortus and B. canis, however, they are reservoirs for different serovars of Leptospira spp