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Simon Chioma Weli Malachy Ifeanyi Okeke Morten Tryland ?ivind Nilssen Terje Traavik 《Canadian journal of veterinary research》2004,68(2):140-145
Avipoxviruses from different geographic regions of the world have been characterized to study their genetic and biological properties, but so far, no such work has been performed on Norwegian isolates. Lesions suggestive of avian pox, found on a Norwegian wild sparrow (Passer domesticus) and wood pigeon (Palumbus palumbus), were obtained in 1972 and 1996, respectively. Histologically, these lesions were demonstrated to be characteristic of poxvirus infections and the poxvirus was observed using an electron microscope. The resulting viruses were propagated in chicken embryo fibroblast cells. Restriction fragment length polymorphism of genomes from 2 Norwegian isolates and fowl pox vaccine strain, generated by BamHI, revealed a high degree of heterogeneity among the isolates. The profiles of avipoxviruses isolated from wild birds were clearly distinct from each other and also to the fowl poxvirus strain. Furthermore, chickens experimentally infected with pigeon poxvirus had higher antibody titers and extensive lesions compared to other isolates. This may suggest that pigeon poxvirus is more virulent than the other isolates. 相似文献
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Summary
L. cyanella L. is known to occur in Europe, Siberia, and Japan. A map showing personal records ofL. cyanella on creeping thistle(Cirsium arvense) is given in Figure 2. Our findings suggest thatL. cyanella is more common and more evenly distributed in the western parts of Europe (western France and southern England) than in central
Europe (Switzerland, Germany, Austria), where only a very small proportion of the thistle stands examined yielded the beetle.
There are no personal records from southern Europe. The hibernating adults ofL. cyanella appear in late April and May on the rosettes and young shoots ofC. arvense, where they start feeding and ovipositing. The larvae which are covered with their faeces feed on the lower side of the leaves
ofC. arvense. Pupation takes place in the soil. In the laboratory the whole development from egg to adult lasted about 35 days. There
is only one generation per annuum. All available field observations ofL. cyanella refer toC. arvense as host plant (one record fromCirsium vulgare). “Short-term feeding tests” with adults ofL. cyanella yielded feeding responses withCarduus,Cirsium spp. andSilybum. Test plants belonging to 17 other genera of the Compositae family were not accepted. As shown in Table 1 this “Carduus-Cirsium-Silybum pattern” has also been found in feeding experiments with other highly specialized thistle insects. Within its subfamily (Criocerinae)L. cyanella appears to have developed a unique host association, since to date no related species are known to feed on thistles or other
Cynareae. Because of its high degree of host specifityL. cyanella may be a potential candidate insect for the biological control of creeping thistle in North America. Further feeding tests
with larvae and investigations as to the reasons for the scarcity ofL. cyanella in central Europe should be made, before a definite decision about the usefulness ofL. cyanella as a biological control agent can be taken.
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Reactivation of the paternal X chromosome in early mouse embryos 总被引：2，自引：0，他引：2
Mak W Nesterova TB de Napoles M Appanah R Yamanaka S Otte AP Brockdorff N 《Science (New York, N.Y.)》2004,303(5658):666-669
It is generally accepted that paternally imprinted X inactivation occurs exclusively in extraembryonic lineages of mouse embryos, whereas cells of the embryo proper, derived from the inner cell mass (ICM), undergo only random X inactivation. Here we show that imprinted X inactivation, in fact, occurs in all cells of early embryos and that the paternal X is then selectively reactivated in cells allocated to the ICM. This contrasts with more differentiated cell types where X inactivation is highly stable and generally irreversible. Our observations illustrate that an important component of genome plasticity in early development is the capacity to reverse heritable gene silencing decisions. 相似文献
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Bird W 《Science (New York, N.Y.)》2011,331(6023):1385
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