Cellular distribution of GAP-43 mRNA in hippocampus and cerebellum of adult rat brain by in situ RT-PCR.

The growth-associated protein GAP-43 is a presynaptic membrane phosphoprotein that plays a key role in guiding the growth of axons and in modulating the formation of new synapses. To identify the cells that synthesize GAP-43 mRNA, we applied direct in situ reverse transcription-polymerase chain reaction (in situ RT-PCR) in cerebellum and hippocampus of adult rat brain. In situ RT-PCR revealed GAP-43 mRNA in cerebellar granule cells, in Purkinje cells and in some interneurons of the molecular layer. Previous in situ hybridization studies had demonstrated a dense label throughout the granular layer of the cerebellar cortex but no labeling of other cerebellar neurons. Hippocampal cells showing distinct GAP-43 mRNA signal after in situ RT-PCR were CA1 and CA3 pyramidal neurons, CA4 hilar cells, and dentate gyrus granule cells, whereas in situ hybridization studies had detected GAP-43 mRNA only in CA3 and CA1 pyramidal neurons. Our data indicate that GAP-43 mRNA is widely distributed, suggesting that many cell types are potentially involved in synaptic plasticity events. (J Histochem Cytochem 49:1195-1196, 2001)

A gender--dependent genetic predisposition to produce high levels of IL-6 is detrimental for longevity.

Current literature indicates that elevated IL-6 serum levels are associated with diseases, disability and mortality in the elderly. In this paper, we studied the IL-6 promoter genetic variability at -174 C/G locus and its effect on IL-6 serum levels in a total of 700 people from 60 to 110 years of age, including 323 centenarians. We found that the proportion of homozygotes for the G allele at -174 locus decreases in centenarian males, but not in centenarian females. Moreover, we found that, only among males, homozygotes for the G allele at -174 locus have higher IL-6 serum levels in comparison with carriers of the C allele. On the whole, our data suggest that those individuals who are genetically predisposed to produce high levels of IL-6 during aging, i.e. -174 locus GG homozygous men, are disadvantaged for longevity.

Increase of homozygosity in centenarians revealed by a new inter-Alu PCR technique.

In the present study a novel inter-Alu PCR technique that allows one to detect inter-individual differences in the genomic regions flanked by Alu repetitive sequences was developed. Two primers complementary to sequences present in different Alu repeats and marked with two different fluorochromes were used in the same PCR reaction, and the PCR products were separated and analyzed by capillary electrophoresis using an automatic sequencer. The method is highly reliable, and three patterns of peaks (QM376-400, QM780-790 and QM480) appeared to be representative for germ-line polymorphisms, as suggested by the results obtained in nine couples of monozygotic twins and four three-generation families. The frequency of these polymorphic peaks was studied in two different age groups (100 young subjects and 69 centenarians). In two out of the three regions (QM376-400 and QM480) a significant increase in homozygote genotypes frequency was observed in centenarians. These counterintuitive results suggest that increased homozygosity contributes to human longevity. This novel inter-Alu PCR approach could represent a valuable tool to identify longevity-associated DNA sequences interspersed throughout human genome, without making any a priori assumption about their nature and function.