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31.
Two orthologous linkage groups have been mapped in sheep and deer. Seven loci have been mapped in deer, and 12 in sheep. The sheep linkage group is assigned to ovine chromosome 24. The linkage groups consist of loci from the short arm of human chromosome 16, spanning the region containing the human Batten disease locus, and from human chromosome 7. One locus from the long arm of human chromosome 16 is also present, demonstrating a previously unknown rearrangement between human and ruminant chromosomes. There is no significant difference in marker order and distances between the two linkage groups, implying that this linkage pattern was present in the genome of the common ancestor of the pecora ruminants. 相似文献
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The behaviour of dace infected with Diplostomum spathaceum was investigated in the laboratory. As the number of parasites present in the eye increased, the efficiency with which the fish fed on Gammarus pulex declined. The loss of efficiency was compensated for by an increase in the time devoted to feeding. Heavily infected fish spent more time in the surface layers of the water. This may increase the likelihood that a gull might eat the fish and thereby continue the life-cycle of the parasite. The parasite modifies the behaviour of its host in a way that increases the parasite's chances of survival at the expense of the host. 相似文献
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ADP-ribosylation is involved in the integration of foreign DNA into the mammalian cell genome. 总被引:6,自引:3,他引:3 下载免费PDF全文
F Farzaneh G N Panayotou L D Bowler B D Hardas T Broom C Walther S Shall 《Nucleic acids research》1988,16(23):11319-11326
The most commonly used DNA transfection method, which employs the calcium phosphate co-precipitation of the donor DNA, involves several discrete steps (1,2). These include the uptake of the donor DNA by the recipient cells, the transport of the DNA to the nucleus, transient expression prior to integration into the host cell genome, concatenation and integration of the transfected DNA into the host cell genome and finally the stable expression of the integrated genes (2,3). Both the concatenation and the integration of the donor DNA into the host genome involve the formation and ligation of DNA strand-breaks. In the present study we demonstrate that the nuclear enzyme, adenosine diphosphoribosyl transferase (ADPRT, E.C. 2.4.2.30), which is dependent on the presence of DNA strand breaks for its activity (4,5) and necessary for the efficient ligation of DNA strand-breaks in eukaryotic cells (4,6), is required for the integration of donor DNA into the host genome. However, ADPRT activity does not influence the uptake of DNA into the cell, its episomal maintenance or replication, nor its expression either before or after integration into the host genome. These observations strongly suggest the involvement of ADPRT activity in eukaryotic DNA recombination events. 相似文献
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Wahlin S Floderus Y Ros AM Broomé U Harper P 《Physiological research / Academia Scientiarum Bohemoslovaca》2006,55(Z2):S155-S157
We give a short survey of the Swedish erythropoietic protoporphyria patients (EPP) with respect to the lapsed time between symptom debut and diagnosis. With two examples we illustrate the consequence of undiagnosed EPP for the patient and also the family. We recall efforts to spread information among health workers in order to investigate patients suffering from extreme sun-exposure intolerance for this uncommon kind of porphyria as well. 相似文献
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Chemically defended species often have conspicuous signals that warn potential predators of these defences. Recent evidence
suggests that some such aposematic prey are not as conspicuous as possible, even though increased conspicuousness would bring
additional anti-predator benefits. Here we present a simple model to explore the generality of these observations. Our model
predicts that optimal fitness will often be achieved at an intermediate level of conspicuousness and not simply by maximising
conspicuousness. This comes about because of the ubiquitous trade-off that increased conspicuousness has an ecological cost
in increasing the encounter rate with predators, as well as a benefit in terms of enhancing learned aversion by predators
of defended prey. However, importantly, we also predict that a small deviation away from maximal crypsis generally causes
a decrease in fitness, even if a larger deviation would lead to an intermediate level of conspicuousness that maximises fitness.
Hence, further consideration of whether intermediate levels of aposematism are as common in nature as predicted in this model
will require consideration of the underlying evolution of appearance, and the plausibility of evolution across the fitness
trough, from maximal crypsis to an intermediate level of aposematism. 相似文献
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