Hosts have evolved a multiplicity of defensive responses against avian brood parasites. One of them is mobbing behaviour which often includes direct contact attacks. These aggressive strikes may not only distract the parasites but may also be fatal to them, as documented by cases of dead brood parasite females found near host nests. Here, we present the first video-recording of a great reed warbler (Acrocephalus arundinaceus) host whose vigorous nest defence appears to directly lead to the death of a female common cuckoo (Cuculus canorus). We suggest that the chance of parasite death probably rises with the presence of unfavourable factors, such as water below the nest. Our observation supports previous suggestions that hosts may pose a lethal danger to their parasites.
We investigated the variation in body colour and its thermoregulatory function in Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae), a parasitoid wasp of Spodoptera and other free-living lepidopteran larvae. We show that the body colour of adult wasps darkens when cocoons are kept at low temperatures. The range in the variation in colour, however, differs for different parts of the body and among uniparental (thelytokous) strains. This melanism enables these wasps to attain a body temperature in sunshine up to 2°C. Moreover, this small gain in body temperature can markedly increase the flight activity of wasps at low ambient temperatures. We conclude that the variation in body colour that resulted from rearing the cocoons at different temperatures enable the wasps to adapt to changing thermal environments. The ecological significance of the difference in the degree of melanism of the different strains is discussed., Yosuke Abe, Takuma Nishimura, Kaoru Maeto., and Seznam literatury
Black rats and avian cavity-nesters share the same nest boxes in different oak habitat types on Corsica. The proportion of boxes occupied by cavity-nesting rats did not differ between broad-leaf deciduous and evergreen oak woodland, but was higher in boxes with a larger entrance hole. Competition between black rat and avian hole-nesters on Corsica may be stronger in great tits than in blue tits.
The notion of Cayley color graphs of groups is generalized to inverse semigroups and groupoids. The set of partial automorphisms of the Cayley color graph of an inverse semigroup or a groupoid is isomorphic to the original inverse semigroup or groupoid. The groupoid of color permuting partial automorphisms of the Cayley color graph of a transitive groupoid is isomorphic to the original groupoid.
The CD8+ natural killer (NK) subpopulation has recently been identified as a fast and reliable biodosimetric indicator within human peripheral blood mononuclear cells (PBMC) in vitro. In irradiated and subsequently cultivated PBMC, a decrease of the relative number of intact CD3-CD8+ lymphocytes 16 and 48 h after treatment has allowed for estimating the received dose in the range of 0 - 10 Gy and lethal/sublethal dose discrimination, respectively. Here we show that suitable biodosimeters can also be found in the peripheral blood B-cell compartment. Multiparameter flow cytometric analysis of irradiated and subsequently cultivated human PBMC revealed that both the CD27+ and CD21- B-cell subpopulations can be used as biodosimeters and the CD19+CD27+ lymphocytes have proved useful for retrospective determination of the received dose in the range of 0 - 6 Gy. In addition, several CD19+ lymphocyte subsets characterized by co-expression of CD21, CD27 and CD38 have been shown to bear biodosimetric potential, too. However, when important parameters like the original size within the CD19+ compartment, its radiation-induced changes and data variation had been taken into account, the CD27+ subpopulation proved superior to the other B-cell subpopulations and subsets. It appears that, in the dose range of 0 - 6 Gy, the relative decrease of CD27+ B lymphocytes provides more sensitive and reliable data than that of CD8+ NK-cells due mainly to lower data variation. In contrast to CD27+ B-cells, the proportions of CD27+ subpopulations of T-cells were not affected by irradiation. We have also proposed a simple experimental protocol based on full blood cultivation and three-color CD27/CD3/CD19 immuno-phenotyping as a time-saving and inexpensive approach for practical biodosimetric evaluations on simple, three-to-four color flow cytometers., Z. Řeháková, J. Šinkora, M. Vlková, D. Vokurková, J. Österreicher, J. Vávrová, D. Driák., and Obsahuje bibliografii a bibliografické odkazy
In the current study, we tested a hypothesis that CD36 fatty acid (FA) transporter might affect insulin sensitivity by indirect effects on FA composition of adipose tissue. We examined the effects of CD36 downregulation by RNA interference in 3T3-L1 adipocytes on FA transport and composition and on sensitivity to insulin action. Transfected 3T3-L1 adipocytes, without detectable CD36 protein, showed reduced neutral lipid levels and significant differences in FA composition when levels of essential FA and their metabolites were lower or could not be detected including gamma linolenic (C18:3 n6), eicosadienic (C20:2 n6), dihomo-gamma linolenic (C20:3 n6), eicosapentaenoic (EPA) (C20:5 n3), docosapentaenoic (DPA) (C22:5 n3), and docosahexaenoic (DHA) (C22:6 n3) FA. Transfected 3T3-L1 adipocytes exhibited a significantly higher n6/n3 FA ratio, reduced Δ5-desaturase and higher Δ9-desaturase activities. These lipid profiles were associated with a significantly reduced insulin-stimulated glucose uptake (4.02±0.1 vs. 8.42±0.26 pmol.10-3 cells, P=0.001). These findings provide evidence that CD36 regulates FA composition thereby affecting sensitivity to insulin action in 3T3-L1 adipocytes., K. Kontrová, J. Zídková, B. Bartoš, V. Skop, J. Sajdok, L. Kazdová, K. Mikulík, P. Mlejnek, V. Zídek, M. Pravenec., and Obsahuje bibliografii a bibliografické odkazy
Protective immunity against murine malaria infection depends largely on the establishment of effective Th1 immune response during the early stages of infection. Experimental data suggest that the death of Plasmodium yoelii 17XL (P.y 17XL) susceptible BALB/c mice results from the suppression of Th1 immune response mediated by CD4+CD25+Foxp3+regulatory T cells (Tregs). However, the mechanism by which Tregs regulate Th1 immune response is poorly understood. Since immunity is initiated by dendritic cells (DCs), we analysed DC responses to P.y 17XL in control and Treg-depleted BALB/c mice. Myeloid DC proliferation, phenotypic maturation and interleukin-12 (IL-12) production were strongly inhibited in control BALB/c mice. In contrast, plasmacytoid DC proliferation and IL-10 production were strongly enhanced in control BALB/c mice. In-vivo depletion of Tregs resulted in significantly reversed inhibition of DC response, which may contribute to the establishment of Th1 immune response, indicating that Tregs contribute to the suppression of Th1 immune response during malaria. These findings suggest Tregs contribute to prevent Th1 immune response establishment during the early stage of P.y 17XL infection by inhibiting DC response.