| 1. |
- Ah-King, Malin, et al.
(författare)
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Genital Evolution : Why Are Females Still Understudied?
- 2014
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 12:5, s. e1001851-
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Tidskriftsartikel (refereegranskat)abstract
- The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.
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| 2. |
- Andersson, Marlene, et al.
(författare)
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Carbonic Anhydrase Generates CO2 and H+ That Drive Spider Silk Formation Via Opposite Effects on the Terminal Domains
- 2014
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 12:8, s. e1001921-
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Tidskriftsartikel (refereegranskat)abstract
- Spider silk fibers are produced from soluble proteins (spidroins) under ambient conditions in a complex but poorly understood process. Spidroins are highly repetitive in sequence but capped by nonrepetitive N- and C-terminal domains (NT and CT) that are suggested to regulate fiber conversion in similar manners. By using ion selective microelectrodes we found that the pH gradient in the silk gland is much broader than previously known. Surprisingly, the terminal domains respond in opposite ways when pH is decreased from 7 to 5: Urea denaturation and temperature stability assays show that NT dimers get significantly stabilized and then lock the spidroins into multimers, whereas CT on the other hand is destabilized and unfolds into ThT-positive beta-sheet amyloid fibrils, which can trigger fiber formation. There is a high carbon dioxide pressure (pCO(2)) in distal parts of the gland, and a CO2 analogue interacts with buried regions in CT as determined by nuclear magnetic resonance (NMR) spectroscopy. Activity staining of histological sections and inhibition experiments reveal that the pH gradient is created by carbonic anhydrase. Carbonic anhydrase activity emerges in the same region of the gland as the opposite effects on NT and CT stability occur. These synchronous events suggest a novel CO2 and proton-dependent lock and trigger mechanism of spider silk formation.
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| 3. |
- Benson, Roger B. J., et al.
(författare)
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Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage
- 2014
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 12:5, s. e1001853-
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages.
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| 5. |
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| 6. |
- Bozek, Katarzyna, et al.
(författare)
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Exceptional evolutionary divergence of human muscle and brain metabolomes parallels human cognitive and physical uniqueness.
- 2014
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Metabolite concentrations reflect the physiological states of tissues and cells. However, the role of metabolic changes in species evolution is currently unknown. Here, we present a study of metabolome evolution conducted in three brain regions and two non-neural tissues from humans, chimpanzees, macaque monkeys, and mice based on over 10,000 hydrophilic compounds. While chimpanzee, macaque, and mouse metabolomes diverge following the genetic distances among species, we detect remarkable acceleration of metabolome evolution in human prefrontal cortex and skeletal muscle affecting neural and energy metabolism pathways. These metabolic changes could not be attributed to environmental conditions and were confirmed against the expression of their corresponding enzymes. We further conducted muscle strength tests in humans, chimpanzees, and macaques. The results suggest that, while humans are characterized by superior cognition, their muscular performance might be markedly inferior to that of chimpanzees and macaque monkeys.
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| 7. |
- Bozhkov, Peter
(författare)
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A Bipartite Molecular Module Controls Cell Death Activation in the Basal Cell Lineage of Plant Embryos
- 2013
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Plant zygote divides asymmetrically into an apical cell that develops into the embryo proper and a basal cell that generates the suspensor, a vital organ functioning as a conduit of nutrients and growth factors to the embryo proper. After the suspensor has fulfilled its function, it is removed by programmed cell death (PCD) at the late stages of embryogenesis. The molecular trigger of this PCD is unknown. Here we use tobacco (Nicotiana tabacum) embryogenesis as a model system to demonstrate that the mechanism triggering suspensor PCD is based on the antagonistic action of two proteins: a protease inhibitor, cystatin NtCYS, and its target, cathepsin H-like protease NtCP14. NtCYS is expressed in the basal cell of the proembryo, where encoded cystatin binds to and inhibits NtCP14, thereby preventing precocious onset of PCD. The anti-cell death effect of NtCYS is transcriptionally regulated and is repressed at the 32-celled embryo stage, leading to increased NtCP14 activity and initiation of PCD. Silencing of NtCYS or overexpression of NtCP14 induces precocious cell death in the basal cell lineage causing embryonic arrest and seed abortion. Conversely, overexpression of NtCYS or silencing of NtCP14 leads to profound delay of suspensor PCD. Our results demonstrate that NtCYS-mediated inhibition of NtCP14 protease acts as a bipartite molecular module to control initiation of PCD in the basal cell lineage of plant embryos.
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| 8. |
- Brochet, Mathieu, et al.
(författare)
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Phosphoinositide metabolism links cGMP-dependent protein kinase G to essential Ca²⁺ signals at key decision points in the life cycle of malaria parasites
- 2014
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Ingår i: PLoS biology. - : Public Library of Science. - 1544-9173 .- 1545-7885. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Many critical events in the Plasmodium life cycle rely on the controlled release of Ca²⁺ from intracellular stores to activate stage-specific Ca²⁺-dependent protein kinases. Using the motility of Plasmodium berghei ookinetes as a signalling paradigm, we show that the cyclic guanosine monophosphate (cGMP)-dependent protein kinase, PKG, maintains the elevated level of cytosolic Ca²⁺ required for gliding motility. We find that the same PKG-dependent pathway operates upstream of the Ca²⁺ signals that mediate activation of P. berghei gametocytes in the mosquito and egress of Plasmodium falciparum merozoites from infected human erythrocytes. Perturbations of PKG signalling in gliding ookinetes have a marked impact on the phosphoproteome, with a significant enrichment of in vivo regulated sites in multiple pathways including vesicular trafficking and phosphoinositide metabolism. A global analysis of cellular phospholipids demonstrates that in gliding ookinetes PKG controls phosphoinositide biosynthesis, possibly through the subcellular localisation or activity of lipid kinases. Similarly, phosphoinositide metabolism links PKG to egress of P. falciparum merozoites, where inhibition of PKG blocks hydrolysis of phosphatidylinostitol (4,5)-bisphosphate. In the face of an increasing complexity of signalling through multiple Ca²⁺ effectors, PKG emerges as a unifying factor to control multiple cellular Ca²⁺ signals essential for malaria parasite development and transmission.
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| 9. |
- Bülow, Morten Hillgaard, 1979-, et al.
(författare)
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Becoming Transdisciplinary? : Three Dialogues
- 2011
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Ingår i: PLoS biology. - 1544-9173 .- 1545-7885. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- The Neuroschool, and in particular the Experiment contest with which the week culminated, was a transformative experience for the 2010 Alumni. The participants were determined to continue reflecting on the ways in which this experience had affected their perspectives on research and so, scattered across the globe, each Experiment team organised a Skype meeting to discuss a list of questions derived in collaboration with Dr Giovanni Frazzetto. Their aim was to produce group dialogues that would help participants clarify what they had learned about transdisciplinarity, and which would also communicate to others the experience of taking part in The Experiment. Further, the group production of this report was itself a way in which to continue addressing the challenges of transdisciplinary collaboration.
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| 10. |
- Bülow, Morten Hillgaard, 1979-, et al.
(författare)
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Becoming Transdisciplinary? : Three Dialogues
- 2010
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Ingår i: PLoS biology. - : www.plosbiology.org. - 1544-9173 .- 1545-7885. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- The Neuroschool, and in particular the Experiment contest with which the week culminated, was a transformative experience for the 2010 Alumni. The participants were determined to continue reflecting on the ways in which this experience had affected their perspectives on research and so, scattered across the globe, each Experiment team organised a Skype meeting to discuss a list of questions derived in collaboration with Dr Giovanni Frazzetto. Their aim was to produce group dialogues that would help participants clarify what they had learned about transdisciplinarity, and which would also communicate to others the experience of taking part in The Experiment. Further, the group production of this report was itself a way in which to continue addressing the challenges of transdisciplinary collaboration.
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