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Pohjoismäki, J. L. O.

Publications and source records attributed to Pohjoismäki, J. L. O..

2 recordsLinked to original sources

The type and source of reactive oxygen species influences the outcome of oxidative stress in cultured cells

Oxidative stress can be modeled using various different experimental approaches, such as exposing the cells or organisms to oxidative chemicals. However, the actual effects of these chemicals, outside of the immediate measured effect, have attracted relatively little attention. We show here that three commonly used oxidants, menadione, potassium bromate and hydrogen peroxide, while known to function differently, also elicit different types of responses in cultured cells. While cells response to menadione and bromate exposure mainly by an integrated stress response, hydrogen peroxide has more indirect effects. Primary oxidative stress does not induce DNA repair or antioxidant defense mechanisms. However, cells with previous experience of oxidative stress show adaptive changes when the stress is renewed. Our results urge caution when comparing studies using different sources of oxidative stress or generalizing the findings of these studies to different tissue or oxidant types.

cell biology↗

Promiscuous specialists: Host specificity patterns among generalist louse flies

Ectoparasites such as louse flies (Diptera: Hippoboscidae) have tendency for host specialization, which is driven by adaptation to host biology as well as competition avoidance between parasites of the same host. However, some louse fly species, especially in genera attacking birds, show wide range of suitable hosts. In the presented study, we have surveyed the current status of bird attacking louse flies in Finland to provide comprehensive host association data to analyse the ecological requirements of the generalist species. A thorough sampling of 9342 birds, representing 134 species, recovered 576 specimens of louse flies, belonging to six species: Crataerina hirundinis, C. pallida, Ornithomya avicularia, O. chloropus, O. fringillina and Ornithophila metallica. Despite some overlapping hosts, the three Ornithomya species showed a notable pattern in their host preference, which was influenced not only by the host size but also by the habitat and host breeding strategy. We also provide DNA barcodes for most Finnish species of Hippoboscidae, which can be used as a resource for species identification as well as metabarcoding studies in the future.

zoology↗