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- Dahlin, C., et al.
(författare)
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Protochlorophyllide-independent import of two NADPH : Pchlide oxidoreductase proteins (PORA and PORB) from barley into isolated plastids
- 2000
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Ingår i: Physiologia Plantarum. - Copenhagen : Munksgaard Forlag. - 0031-9317 .- 1399-3054. ; 109:3, s. 298-303
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Forskningsöversikt (refereegranskat)abstract
- The enzyme catalysing the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), NADPH:Pchlide oxidoreductase (POR; EC 1.6.99.1), is a nuclear-encoded protein that is post-translationally imported to the plastid, In barley and Arabidopsis thaliana, the reduction of Pchlide is controlled by two different PORs, PORA and PORE. To characterise the possible Pchlide dependency for the import reaction, radiolabelled precursor proteins of barley PORA and PORE (pPORA and pPORB, respectively) were used for in vitro assays with isolated plastids of barley and pea with different contents of Pchlide, To obtain plastids with different endogenous levels of Pchlide, several methods were used. Barley plants were grown in darkness or in greenhouse conditions for 6 days. Alternatively, greenhouse-grown pea plants were incubated for 4 days in darkness before plastid isolation, or chloroplasts isolated from greenhouse-grown plants were incubated with delta-aminolevulinic acid (ALA), an early precursor in the Chi biosynthesis resulting in elevated Pchlide contents in the plastids, Both barley pPORA and pPORB were effectively imported into barley and pea chloroplasts isolated from the differentially treated plants, including those isolated from greenhouse-grown plants. The absence or presence of Pchlide did not significantly affect the import capacity of barley pPORA or pPORB, Assays performed on stroma-enriched fractions from chloroplasts and etioplasts of barley indicated that no post-import degradation of the proteins occurred in the stroma, irrespective of whether the incubation was performed in darkness or in light.
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| 2. |
- Jonsdottir, I.H.
(författare)
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Neuropeptides and their interaction with exercise and immune function
- 2000
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Ingår i: Immunology and Cell Biology. - Oxford : Blackwell Publishing. - 0818-9641 .- 1440-1711. ; 78:5, s. 562-570
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Forskningsöversikt (refereegranskat)abstract
- It is known today that the immune system is influenced by various types of psychological and physiological stressors, including physical activity. It is well known that physical activity can influence neuropeptide levels both in the central nervous system as well as in peripheral blood. The reported changes of immune function in response to exercise have been suggested to be partly regulated by the activation of different neuropeptides and the identification of receptors for neuropeptides and steroid hormones on cells of the immune system has created a new dimension in this endocrine-immune interaction. It has also been shown that immune cells are capable of producing neuropeptides, creating a bidirectional link between the nervous and immune systems. The most common neuropeptides mentioned in this context are the endogenous opioids. The activation of endogenous opioid peptides in response to physical exercise is well known in the literature, as well as the immunomodulation mediated by opioid peptides. The role of endogenous opioids in the exercise-induced modulation of immune function is less clear. The present paper will also discuss the role of other neuroendocrine factors, such as substance P, neuropeptide Y and vasoactive intestinal peptide, and pituitary hormones, including growth hormone, prolactin and adrenocorticotrophin, in exercise and their possible effects on immune function.
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