Discrepancy variation of dinucleotide microsatellite repeats in eukaryotic genomes

To address whether there are differences of variation among repeat motif types and among taxonomic groups, we present here an analysis of variation and correlation of dinucleotide microsatellite repeats in eukaryotic genomes. Ten taxonomic groups were compared, those being primates, mammalia (excluding primates and rodentia), rodentia, birds, fish, amphibians and reptiles, insects, molluscs, plants and fungi, respectively. The data used in the analysis is from the literature published in the Journal of Molecular Ecology Notes. Analysis of variation reveals that there are no significant differences between AC and AG repeat motif types. Moreover, the number of alleles correlates positively with the copy number in both AG and AC repeats. Similar conclusions can be obtained from each taxonomic group. These results strongly suggest that the increase of SSR variation is almost linear with the increase of the copy number of each repeat motif. As well, the results suggest that the variability of SSR in the genomes of low-ranking species seem to be more than that of high-ranking species, excluding primates and fungi.

Exploratory study on natural focus and its causative agent of genotype of Lyme disease by polymerase chain reaction in the forest areas of Beijing / 中华流行病学杂志

<p><b>OBJECTIVE</b>To learn the existence of natural focus of Lyme disease and its distribution.</p><p><b>METHODS</b>A semi-nested polymerase chain reaction (PCR) method was developed for detection and genotyping of Borrelia burgdorferi on basis of outer surface protein A (OspA) gene. Ticks and mice collected from 6 forest areas in Beijing were detected with above methods. The positive PCR products were cloned and sequenced. The sequences were compared with published sequences for homology. IFA as used to detect IgG antibody on Borrelia burgdorferi. Lyme disease spirochete were isolated from H. longicornis were also attempted.</p><p><b>RESULTS</b>B. Burgdorferi sensu lato were detected from 939 ticks and 250 mice specimens collected from above 6 study sites using primer pairs OA(1)/OA(4) and SL/OA(4). Only the specimens collected from Dongling mountain showed positive amplification. One in three adult Ixodes persulcatus with one of 57 nymph Ixodes persulcatus showed positive while 9 of 119 (7.56%) mice specimens showed positive, of which 8 were B. grinii and one B. afzelii. In this study, we attempted to isolate B. burgdorferi sensu lato strains from 160 H. longicornis ticks (20/group) but failed. Serological survey showed a 9.1% (5/55) infection rate with B. burgdorferi sensu lato in the mice of Dongling mountain forest areas.</p><p><b>CONCLUSIONS</b>The natural focus of Lyme disease including B. garinii and B. afzelii might have existed in Dongling mountain of Mentougou district, Beijing. Ixodes persulcatu and mice may serve as vectors and reservoirs, respectively.</p>

mRNA of MAGE genes as specific markers in detection of tumor cells in the peripheral blood of patients with hepatocellular carcinoma / 中华预防医学杂志

<p><b>OBJECTIVE</b>To detect tumor cells in the peripheral blood of patients with hepatocellular carcinoma (HCC) by using the mRNA of the MAGE-1 and MAGE-3 genes as specific tumor markers.</p><p><b>METHODS</b>Peripheral blood was obtained from 25 HCC patients and 20 healthy volunteers. The mRNA of the MAGE-1 and MAGE-3 genes in the peripheral blood mononuclear cells (PBMCs) was detected by nested RT-PCR. The MAGE-1 and MAGE-3 transcripts in the tumor tissues of these HCC patients were also detected by RT-PCR.</p><p><b>RESULTS</b>Of the 25 HCC patients, MAGE-1 and MAGE-3 mRNA were positive in 44% (11/25) and 36% (9/25) of PBMCs respectively, and in 68% (17/25) and 56% (14/25) of HCC tissues respectively. In the PBMCs of the 25 HCC patients, 16 (64%) samples were detected to express at least one type of MAGE mRNA. MAGE mRNA were not detected in the PBMCs from the patients whose tumors did not express the MAGE genes, nor in the PBMCs from the 20 healthy donors. The positive rate of MAGE mRNA in the PBMCs was closely correlated with the TNM stages and the diameter of tumors, but there was no correlation between the positive rate of MAGE mRNA in PBMCs and tumor differentiation degree or serum alpha-FP level. Of 9 HCC patients whose serum alpha-FP was normal or slightly elevated (< 50 ng/ml), 6 were MAGE-1 and/or MAGE-3 mRNA positive in their PBMCs.</p><p><b>CONCLUSION</b>MAGE-1 and MAGE-3 mRNA could be specifically detected with high percentage in the PBMCs of HCC patients by our method. They can be used as specific tumor markers for the detection of the circulating HCC cells, and the detection results may be helpful to evaluate the prognosis of HCC patients.</p>