Is there a contradiction here?
Wirth T, Wang X, Linz B, Novick RP, Lum JK, Blaser M, Morelli G, Falush D, Achtman M. Distinguishing human ethnic groups by means of sequences from Helicobacter pylori: Lessons from Ladakh. Proc Natl Acad Sci U S A. 2004 Mar 29
Department of Molecular Biology, Max-Planck-Institut fur Infektionsbiologie, Schumannstrasse 21/22, 10117 Berlin, Germany; ( paragraph sign )Skirball Institute of Biomolecular Medicine and ()Department of Medicine, New York University School of Medicine, 540 First Avenue, NY 10016.
The history of mankind remains one of the most challenging fields of study. However, the emergence of anatomically modern humans has been so recent that only a few genetically informative polymorphisms have accumulated. Here, we show that DNA sequences from Helicobacter pylori, a bacterium that colonizes the stomachs of most humans and is usually transmitted within families, can distinguish between closely related human populations and are superior in this respect to classical human genetic markers. H. pylori from Buddhists and Muslims, the two major ethnic communities in Ladakh (India), differ in their population-genetic structure. Moreover, the prokaryotic diversity is consistent with the Buddhists having arisen from an introgression of Tibetan speakers into an ancient Ladakhi population. H. pylori from Muslims contain a much stronger ancestral Ladakhi component, except for several isolates with an Indo-European signature, probably reflecting genetic flux from the Near East. These signatures in H. pylori sequences are congruent with the recent history of population movements in Ladakh, whereas similar signatures in human microsatellites or mtDNA were only marginally significant. H. pylori sequence analysis has the potential to become an important tool for unraveling short-term genetic changes in human populations.
Datta S, Chattopadhyay S, Balakrish Nair G, Mukhopadhyay AK, Hembram J, Berg DE, Rani Saha D, Khan A, Santra A, Bhattacharya SK, Chowdhury A. Virulence genes and neutral DNA markers of Helicobacter pylori isolates from different ethnic communities of West Bengal, India. J Clin Microbiol. 2003 Aug;41(8):3737-43.
National Institute of Cholera and Enteric Diseases, Beliaghata, Calcutta 700010, India.
Virulence-associated genes and neutral DNA markers of Helicobacter pylori strains from the Santhal and Oroan ethnic minorities of West Bengal, India, were studied. These people have traditionally been quite separate from other Indians and differ culturally, genetically, and linguistically from mainstream Bengalis, whose H. pylori strains have been characterized previously. H. pylori was found in each of 49 study participants, although none had peptic ulcer disease, and was cultured from 31 of them. All strains carried the cag pathogenicity island and potentially toxigenic s1 alleles of vacuolating cytotoxin gene (vacA) and were resistant to at least 8 micro g of metronidazole per ml. DNA sequence motifs in vacA mid-region m1 alleles, cagA, and an informative insertion or deletion motif next to cagA from these strains were similar to those of strains from ethnic Bengalis. Three mobile elements, IS605, IS607, and ISHp608, were present in 29, 19, and 10%, respectively, of Santhal and Oroan strains, which is similar to their prevalence in Bengali H. pylori. Thus, there is no evidence that the gene pools of H. pylori of these ethnic minorities differ from those of Bengalis from the same region. This relatedness of strains from persons of different ethnicities bears on our understanding of H. pylori transmission between communities and genome evolution.
