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1.
Wanwisa Dejnirattisai Daming Zhou Helen M. Ginn Helen M.E. Duyvesteyn Piyada Supasa James Brett Case Yuguang Zhao Thomas S. Walter Alexander J. Mentzer Chang Liu Beibei Wang Guido C. Paesen Jose Slon-Campos César López-Camacho Natasha M. Kafai Adam L. Bailey Rita E. Chen Baoling Ying Gavin R. Screaton 《Cell》2021,184(8):2183-2200.e22
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Cultural and biological data suggests the Polynesian origin of the Rapanui population, although the presence of foreign genes
in the native population, as a result of admixture with Europeans in the last two centuries has also to be considered. In
order to estimate the genetic affinities of the present-day inhabitants of Easter Island and the nearby populations, we used
seven polymorphisms of the Y chromosome. However we want to estimate the grade of admixture on the genetic structure that
was brought from foreigners within the last two centuries upon the more geographically isolated populations in the world.
The preliminary results showed the presence of 18 haplotypes analyzed on 30 male samples.
The analysis of the allelic frequency showed a distribution typical of the Polynesian populations. Available data in literature,
even with some differences probably due to either the founder effect or historical and ecological events that created sudden
demographic variations on the island population. The phylogentic analysis of the haplotypes obtained through Network Median
Joining showed two different cluster of haplotypes, of which one represents about 64% of the present haplotypes on Easter
Island, which are characterized from the presence of the allele DYS19*16, very frequent in the Pacific populations. The other cluster is characterized from the presence of the allele DYS19*14, absent within the populations in the Pacific and with reasonable high frequency within the European populations and South
American. Most probably the two clusters are the product of several colonizations that Easter Island had endured from the
time of the Chilian and European Colonies. It was demonstrated in fact, that the arrival in 1914 of 50 German and English
prisoners would have left a considerable genetic impact on the population of Rapanui, which during this period was of small
size. 相似文献
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Occurrence of Drug-Resistant Bacteria in Two European Eel Farms 总被引:5,自引:0,他引:5
The occurrence of strains that are resistant to oxolinic acid, oxytetracycline, sulfamethoxazole-trimethoprim, and nitrofurantoin among heterotrophic bacteria, including human and fish pathogens, in two freshwater eel farms was investigated. High levels of individual- and multiple-drug-resistant bacteria were detected, although sampling events were not correlated with clinical outbreaks and drug therapy. 相似文献
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A new lycopsid family Kladnostrobaceae is proposed, based on the type of sporangia, their attachment by a pedicel and the type of reticulate spores enclosed. All these characteristics distinguish the Kladnostrobaceae from all other lycopsid families. A new lycopsid genus Kladnostrobus nov. gen., consisting of two new species Kladnostrobus clealii nov. sp. and Kladnostrobus psendae nov. sp., is described from the Kladno-Rakovník Basin (Lower Bolsovian) of the central and western Carboniferous continental basins of the Czech Republic. Helically arranged distal laminae and pedicels are relatively primitive, suggesting that Kladnostrobus may represent a new, primitive type of lycopsid cone produced by some unknown, probably arborescent lycopsid parent plant. Spores of Kladnostrobus are about 90-100 μm in diameter, and possess reticulate sculpture. The proximal contact area of spores is laevigate. In situ spores can resemble some dispersed species of the genera Convolutispora Hoffmeister, Staplin and Malloy, Camptotriletes (Naumova) Potonié and Kremp, Reticulatisporites (Ibrahim) Neves and mainly Dictyotriletes (Naumova) Smith and Buttterworth. 相似文献