| 1. |
- Bernander, Rolf, et al.
(författare)
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An archaeal origin for the actin cytoskeleton : implications for eukaryogenesis
- 2011
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Ingår i: Communicative & Integrative Biology. - : Landes Bioscience. - 1942-0889. ; 4:6, s. 664-667
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Tidskriftsartikel (refereegranskat)abstract
- A hallmark of the eukaryotic cell is the actin cytoskeleton, involved in a wide array of processes ranging from shape determination and phagocytosis to intracellular transport and cytokinesis. Recently, we reported the discovery of an actin-based cytoskeleton also in Archaea. The archaeal actin ortholog, Crenactin, was shown to belong to a conserved operon, Arcade (actin-related cytoskeleton in Archaea involved in shape determination), encoding an additional set of cytoskeleton-associated proteins. Here, we elaborate on the implications of these findings for the evolutionary relation between archaea and eukaryotes, with particular focus on the possibility that eukaryotic actin and actin-related proteins have evolved from an ancestral archaeal actin gene. Archaeal actin could thus have played an important role in cellular processes essential for the origin and early evolution of the eukaryotic lineage. Further exploration of uncharacterized archaeal lineages is necessary to find additional missing pieces in the evolutionary trajectory that ultimately gave rise to present-day organisms.
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| 2. |
- Dahl, Tais W., et al.
(författare)
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Do large predatory fish track ocean oxygenation?
- 2011
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Ingår i: Communicative & Integrative Biology. - : Informa UK Limited. - 1942-0889. ; 4:1, s. 92-94
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Tidskriftsartikel (refereegranskat)abstract
- The Devonian appearance of 1-10 meter long armored fish (placoderms) coincides with geochemical evidence recording a transition into fully oxygenated oceans. A comparison of extant fish shows that the large individuals are less tolerant to hypoxia than their smaller cousins. This leads us to hypothesize that Early Paleozoic O2 saturation levels were too low to support >1 meter size marine, predatory fish. According to a simple model, both oxygen uptake and oxygen demand scale positively with size, but the demand exceeds supply for the largest fish with an active, predatory life style. Therefore, the largest individuals may lead us to a lower limit on oceanic O2 concentrations. Our presented model suggests 2-10 meter long predators require >30-50% PAL while smaller fish would survive at <25% PAL. This is consistent with the hypothesis that low atmospheric oxygen pressure acted as an evolutionary barrier for fish to grow much above ~1 meter before the Devonian oxygenation.
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| 3. |
- Hagman, Mattias
(författare)
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Pheromone-induced life-history shifts : a novel approach to controlling invasive toads
- 2010
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Ingår i: Communicative & Integrative Biology. - 1942-0889. ; 3:3, s. 238-239
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Tidskriftsartikel (refereegranskat)abstract
- In a recent paper,1 we showed that recurrent exposure to alarm pheromones reduced development time and size at metamorphosis in larval cane toads (Bufo marinus). Subsequent measurements of post-metamorphic toads revealed larger parotoid glands relative to body size and increased amounts of bufalin (a toxic bufodienalide) in animals from the experimental treatment, suggesting increased investment in chemical defenses. These findings are of interest for evolutionary theory. But the study was also part of a larger conservation-based research program of which this pheromone work was an important component in the development of a management strategy for reducing the ecological impact of invasive cane toads in Australia. For example, our study1 aimed to quantify biochemical and life-history effects as well as assess the likely longterm impact of pheromone exposure on toads. In this addendum, I discuss the conservation potential of our research, with emphasis on exploiting alarm pheromones to induce viability reducing life-history shifts.
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| 4. |
- Johansson, Fredrik, et al.
(författare)
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Theoretical considerations for understanding a Purkinje cell timing mechanism
- 2014
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Ingår i: Communicative & Integrative Biology. - : Informa UK Limited. - 1942-0889. ; 7:6, s. 994376-994376
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Tidskriftsartikel (refereegranskat)abstract
- In classical conditioning, cerebellar Purkinje cells learn an adaptively timed pause in spontaneous firing. This pause reaches its maximum near the end of the interstimulus interval. While it was thought that this timing was due to temporal patterns in the input signal and selective engagement of changes in synapse strength, we have shown Purkinje cells learn timed responses even when the conditional stimulus is delivered to its immediate afferents.(1) This shows that Purkinje cells have a cellular timing mechanism. The cellular models of intrinsic timing we are aware of are based on adapting the rise time of the concentration of a given ion. As an alternative, we here propose a selection mechanism in abstract terms for how a Purkinje cell could learn to respond at a particular time after an external trigger.
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| 5. |
- Liénard, Marjorie, et al.
(författare)
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Functional flexibility as a prelude to signal diversity? Role of a fatty acyl reductase in moth pheromone evolution.
- 2010
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Ingår i: Communicative & Integrative Biology. - : Informa UK Limited. - 1942-0889. ; 3:6, s. 586-588
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Tidskriftsartikel (refereegranskat)abstract
- Sex pheromones are the hallmark of reproductive behavior in moths. Mature females perform the task of mate signaling and release bouquets of odors that attract conspecific males at long range. The pheromone chemistry follows a relatively minimal design but still the combinatorial action of a handful of specialized pheromone production enzymes has resulted in remarkably diverse sexual signals that subtly vary in structure and in number and ratio of components. In a recent article,1 we showed that a single reductase gene (pgFAR) enables the conversion of key biosynthetic fatty-acyl precursors into fatty alcohols, the immediate precursors of the multi-component pheromone in small ermine moths (Lepidoptera: Yponomeutidae). In the light of the widespread usage of multi-component pheromone blends across Lepidoptera, it is likely that the pgFAR biochemical flexibility is a regular feature of the moth pheromone machinery and polyvalent reductase genes are emerging as pivots to promote phenotypic transitions in moth mating signals. In addition, the small ermine moth pgFAR nevertheless contributes to regulating the ratio among components. Here we show that the pgFAR substrate specificity is actually counterbalancing the inherent chain-length preference of an upstream desaturase with Δ11-activity and that the enzymes together modulate the final blend ratio between the Z11-16:OH, Z11-14:OH and E11-14:OH compounds before the final acetylation.
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| 6. |
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| 7. |
- Nordenfelt, Pontus, et al.
(författare)
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The role of calcium in neutrophil granule-phagosome fusion.
- 2010
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Ingår i: Communicative & Integrative Biology. - 1942-0889. ; 3:3, s. 224-226
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Tidskriftsartikel (refereegranskat)abstract
- During phagocytosis, neutrophils kill microorganisms by delivering antimicrobial substances to the phagosome. For this, the intracellular targeting and fusion of granules must be strictly regulated and a dependence on the cytosolic concentration of free calcium has been suggested. New evidence show that different mechanisms regulate early and late stages of Fc receptor-mediated phagocytosis. The early fusion events are dependent on calcium but this is not the case for the fusion of azurophilic granules with phagosomes at later stages. Certain pathogens target the granule-phagosome fusion machinery in order to survive intracellularly; a deeper understanding of intracellular membrane traffic processes could allow new approaches for the eradication of pathogens that are harbored inside the cells of our immune system.
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| 9. |
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| 10. |
- Spetea Wiklund, Cornelia, 1968-, et al.
(författare)
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Solute transporters in plant thylakoid membranes key players during photosynthesis and light stress
- 2010
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Ingår i: Communicative & Integrative Biology. - : Taylor & Francis. - 1942-0889. ; 3:2, s. 122-129
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Tidskriftsartikel (refereegranskat)abstract
- Plants utilize sunlight to drive photosynthetic energy conversion in the chloroplast thylakoid membrane. Here are located four major photosynthetic complexes, about which we have great knowledge in terms of structure and function. However, much less we know about auxiliary proteins, such as transporters, ensuring an optimum function and turnover of these complexes. The most prominent thylakoid transporter is the proton-translocating ATP-synthase. Recently, four additional transporters have been identified in the thylakoid membrane of Arabidopsis thaliana, namely one copper-transporting P-ATPase, one chloride channel, one phosphate transporter, and one ATP/ADP carrier. Here, we review the current knowledge on the function and physiological role of these transporters during photosynthesis and light stress in plants. Subsequently, we make a survey on the outlook of thylakoid activities awaiting identification of responsible proteins. Such knowledge is necessary to understand the thylakoid network of transporters, and to design strategies for bioengineering crop plants in the future.
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