| 1. |
- Dore, Riccardo, et al.
(författare)
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Resistance to thyroid hormone induced tachycardia in RTHα syndrome
- 2023
-
Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in thyroid hormone receptor α1 (TRα1) cause Resistance to Thyroid Hormone α (RTHα), a disorder characterized by hypothyroidism in TRα1-expressing tissues including the heart. Surprisingly, we report that treatment of RTHα patients with thyroxine to overcome tissue hormone resistance does not elevate their heart rate. Cardiac telemetry in male, TRα1 mutant, mice indicates that such persistent bradycardia is caused by an intrinsic cardiac defect and not due to altered autonomic control. Transcriptomic analyses show preserved, thyroid hormone (T3)-dependent upregulation of pacemaker channels (Hcn2, Hcn4), but irreversibly reduced expression of several ion channel genes controlling heart rate. Exposure of TRα1 mutant male mice to higher maternal T3 concentrations in utero, restores altered expression and DNA methylation of ion channels, including Ryr2. Our findings indicate that target genes other than Hcn2 and Hcn4 mediate T3-induced tachycardia and suggest that treatment of RTHα patients with thyroxine in high dosage without concomitant tachycardia, is possible.
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| 2. |
- Herbert-Read, James E., et al.
(författare)
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Proto-cooperation : group hunting sailfish improve hunting success by alternating attacks on grouping prey
- 2016
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 283:1842
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Tidskriftsartikel (refereegranskat)abstract
- We present evidence of a novel form of group hunting. Individual sailfish (Istiophorus platypterus) alternate attacks with other group members on their schooling prey (Sardinella aurita). While only 24% of attacks result in prey capture, multiple prey are injured in 95% of attacks, resulting in an increase of injured fish in the school with the number of attacks. How quickly prey are captured is positively correlated with the level of injury of the school, suggesting that hunters can benefit from other conspecifics' attacks on the prey. To explore this, we built a mathematical model capturing the dynamics of the hunt. We show that group hunting provides major efficiency gains (prey caught per unit time) for individuals in groups of up to 70 members. We also demonstrate that a free riding strategy, where some individuals wait until the prey are sufficiently injured before attacking, is only beneficial if the cost of attacking is high, and only then when waiting times are short. Our findings provide evidence that cooperative benefits can be realized through the facilitative effects of individuals' hunting actions without spatial coordination of attacks. Such 'proto-cooperation' may be the pre-cursor to more complex group-hunting strategies.
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| 3. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Krause, Stefan, et al.
(författare)
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Guppies occupy consistent positions in social networks : mechanisms and consequences
- 2017
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 28:2, s. 429-438
-
Tidskriftsartikel (refereegranskat)abstract
- The social network approach has focused increasing attention on the complex web of relationships found in animal groups and populations. As such, network analysis has been used frequently to identify the role that particular individuals play in their social interactions and this approach has led to the question of whether, and in what context, individuals consistently occupy certain positions within their network. Here we investigated the social networks of guppies, Poecilia reticulata, in the wild and tested whether 1) individual fish occupy consistent positions in their network and 2) whether these positions are robust to experimental manipulations to their habitat. Our habitat manipulations involved increasing and decreasing the surface area of their pools as well as translocating an entire pool population between different pools in situ. We found that guppies did indeed consistently occupy positions within their social networks, irrespective of the type of manipulation and that individual network positions vary between individuals. Our results suggest that at least 2 factors contribute to the observed individual variation in network position including 1) the tendency to be social and 2) sex-specific social preferences. Finally, we used a simulation to explore the implications of individuals consistently occupying different network positions regarding the exposure of fish to parasites and predators. The time until infection decreased with increasing rank of individual betweenness and the predation risk increased with decreasing rank of the individual node strength thus illustrating the potential ecological and evolutionary consequences of consistent network positions.
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| 5. |
- Kurvers, Ralf H. J. M., et al.
(författare)
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The Evolution of Lateralization in Group Hunting Sailfish
- 2017
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 27:4, s. 521-526
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Tidskriftsartikel (refereegranskat)abstract
- Lateralization is widespread throughout the animal kingdom [1-7] and can increase task efficiency via shortening reaction times and saving on neural tissue [8-16]. However, lateralization might be costly because it increases predictability [17-21]. In predator-prey interactions, for example, predators might increase capture success because of specialization in a lateralized attack, but at the cost of increased predictability to their prey, constraining the evolution of lateralization. One unexplored mechanism for evading such costs is group hunting: this would allow individual-level specialization, while still allowing for group-level unpredictability. We investigated this mechanism in group hunting sailfish, Istiophorus platypterus, attacking schooling sardines, Sardinella aurita. During these attacks, sailfish alternate in attacking the prey using their elongated bills to slash or tap the prey [22-24]. This rapid bill movement is either leftward or rightward. Using behavioral observations of identifiable individual sailfish hunting in groups, we provide evidence for individual-level attack lateralization in sailfish. More strongly lateralized individuals had a higher capture success. Further evidence of lateralization comes from morphological analyses of sailfish bills that show strong evidence of one-sided micro-teeth abrasions. Finally, we show that attacks by single sailfish are indeed highly predictable, but predictability rapidly declines with increasing group size because of a lack of population-level lateralization. Our results present a novel benefit of group hunting: by alternating attacks, individual-level attack lateralization can evolve, without the negative consequences of individual-level predictability. More generally, our results suggest that group hunting in predators might provide more suitable conditions for the evolution of strategy diversity compared to solitary life.
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| 6. |
-
- 2019
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Blöcher, Jens, et al.
(författare)
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Descent, marriage, and residence practices of a 3,800-year-old pastoral community in Central Eurasia
- 2023
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 120:36
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Tidskriftsartikel (refereegranskat)abstract
- Our understanding of prehistoric societal organization at the family level is still limited. Here, we generated genome data from 32 individuals from an approximately 3,800-y-old burial mound attributed to the Bronze Age Srubnaya-Alakul cultural tradition at the site of Nepluyevsky, located in the Southern Ural region of Central Eurasia. We found that life expectancy was generally very low, with adult males living on average 8 y longer than females. A total of 35 first-degree, 40 second-degree, and 48 third-degree biological relationships connected 23 of the studied individuals, allowing us to propose a family tree spanning three generations with six brothers at its center. The oldest of these brothers had eight children with two women and the most children overall, whereas the other relationships were monogamous. Notably, related female children above the age of five were completely absent from the site, and adult females were more genetically diverse than males. These results suggest that biological relationships between male siblings played a structural role in society and that descent group membership was based on patrilineality. Women originated from a larger mating network and moved to join the men, with whom they were buried. Finally, the oldest brother likely held a higher social position, which was expressed in terms of fertility.
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| 8. |
- Blösch, Günter, et al.
(författare)
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Twenty-three unsolved problems in hydrology (UPH) - a community perspective
- 2019
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 64:10, s. 1141-1158
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
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| 9. |
- Chapman, Ben, et al.
(författare)
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Behavioural consequences of sensory plasticity in guppies
- 2010
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 277:1686, s. 1395-1401
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Tidskriftsartikel (refereegranskat)abstract
- Sensory plasticity, whereby individuals compensate for sensory deprivation in one sense by an improvement in the performance of an alternative sense, is a well-documented phenomenon in nature. Despite this, the behavioural and ecological consequences of sensory plasticity have not been addressed. Here we show experimentally that some components (vision and chemoreception) of the sensory system of guppies are developmentally plastic, and that this plasticity has important consequences for foraging behaviour. Guppies reared under low light conditions had a significantly stronger response to chemical food cues encountered in isolation than fish reared at higher light levels. Conversely, they exhibited a weaker response to visual-only cues. When visual and olfactory/gustatory cues were presented together, no difference between the strength of response for fish reared at different light intensities was evident. Our data suggest that guppies can compensate for experience of a visually poor, low light environment via a sensory switch from vision to olfaction/gustation. This switch from sight to chemoreception may allow individuals to carry out the foraging behaviour that is essential to their survival in a visually poor environment. These considerations are especially important given the increasing frequency of anthropogenic changes to ecosystems. Compensatory phenotypic plasticity as demonstrated by our study may provide a hitherto unconsidered buffer that could allow animals to perform fundamental behaviours in the face of considerable change to the sensory environment.
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| 10. |
- Chapman, Ben, et al.
(författare)
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Unpredictability in food supply during early life influences boldness in fish
- 2010
-
Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 21:3, s. 501-506
-
Tidskriftsartikel (refereegranskat)abstract
- Behavioral variation has been documented both between and within populations in a variety of traits. Many of these behavioral traits are phenotypically plastic and are conditional on the early environment an animal experiences, yet despite this the role of the environment in generating variation in boldness is not well understood. Here we investigate the importance of early and recent experience of temporal unpredictability in food supply on the behavior of a species of freshwater fish, the Trinidadian guppy Poecilia mticulata. We predict that individuals that experience temporally unpredictable food supplies will engage in more risky behavior than those experiencing a Predictable food supply and find evidence to support this. Fish with early experience of unpredictable environments are generally bolder and more exploratory than fish reared in predictable environments, exploring a significantly greater proportion of a novel maze and spending less time in a refuge during the trial. Individuals with early experience of unpredictability also spent significantly less time associating with conspecifics in a shoaling tendency assay, again suggesting that they are bolder than guppies reared in predictable conditions. These findings suggest that early experience is important in shaping exploratory anti shoaling behavior in this species and that unpredictability in early life can influence boldness in guppies.
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| 11. |
- Christopoulos, Dimitrios, et al.
(författare)
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Multi-User Detection in Multibeam Mobile Satellite Systems : A Fair Performance Evaluation
- 2013
-
Ingår i: 2013 IEEE 77th Vehicular Technology Conference. - 9781467363372
-
Konferensbidrag (refereegranskat)abstract
- Multi-User Detection (MUD) techniques are currently being examined as promising technologies for the next generation of broadband, interactive, multibeam satellite communication (SatCom) systems. Results in the existing literature have shown that when full frequency and polarization reuse is employed and user signals are jointly processed at the gateway, more than threefold gains in terms of spectral efficiency over conventional systems can be obtained. However, the information theoretic results for the capacity of the multibeam satellite channel are given under ideal assumptions, disregarding the implementation constraints of such an approach. Considering a real system implementation, the adoption of full resource reuse is bound to increase the payload complexity and power consumption. Since these novel techniques require extra payload resources, fairness issues in the comparison among the two approaches arise. The present contribution evaluates in a fair manner, the performance of the return link (RL) of a SatCom system serving mobile users that are jointly decoded at the receiver. In this context, the throughput performance of the assumed system is compared to that of a conventional one, under the constraint of equal physical layer resource utilization; thus the comparison can be regarded as fair. Results show, that even when systems operate under the same payload requirements as the conventional systems, a significant gain can be realized, especially in the high SNR region. Finally, existing analytical formulas are also employed to provide closed form descriptions of the performance of clustered systems, thus introducing insights on how the performance scales with respect to the system parameters.
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| 12. |
- Danilo, Spano, et al.
(författare)
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Per-antenna power minimization in symbol-level precoding for the multibeam satellite downlink
- 2018
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Ingår i: International Journal of Satellite Communications And Networking. - : Wiley. - 1542-0973 .- 1542-0981. ; 37:1, s. 15-30
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of multiuser interference in the forward downlink channel of a multibeam satellite system. A symbol-level precoding scheme is considered, to exploit the multiuser interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, a per-antenna power minimization scheme is proposed, under quality-of-service constraints, for multilevel modulation schemes. The consideration of the power limitations individually for each transmitting radio frequency chain is a central aspect of this work, and it allows to deal with systems using separate per-antenna amplifiers. Moreover, this feature is also particularly relevant for systems suffering nonlinear effects of the channel. This is the case of satellite systems, where the nonlinear amplifiers should be properly driven to reduce the detrimental saturation effect. In the proposed scheme, the transmitted signals are designed to reduce the power peaks, while guaranteeing some specific target signal-to-noise ratios at the receivers. Numerical results are presented to show the effectiveness of the proposed scheme, which is compared both with the state of the art in symbol-level precoding and with the conventional minimum mean square error precoding approach.
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| 13. |
- Dudenhöffer-Pfeifer, Monika, et al.
(författare)
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Different Munc13 isoforms function as priming factors in lytic granule release from murine cytotoxic T lymphocytes.
- 2013
-
Ingår i: Traffic. - : Wiley. - 1398-9219 .- 1600-0854. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- In order to fuse lytic granules (LGs) with the plasma membrane at the immunological synapse, cytotoxic T lymphocytes (CTLs) have to render these LGs fusion-competent through the priming process. In secretory tissues such as brain and neuroendocrine glands, this process is mediated by members of the Munc13 protein family. In human CTLs, mutations in the Munc13-4 gene cause a severe loss in killing efficiency, resulting in familial hemophagocytic lymphohistiocytosis type 3, suggesting a similar role of other Munc13 isoforms in the immune system. Here, we investigate the contribution of different Munc13 isoforms to the priming process of murine CTLs at both the mRNA and protein level. We demonstrate that Munc13-1 and Munc13-4 are the only Munc13 isoforms present in mouse CTLs. Both isoforms rescue the drastical secretion defect of CTLs derived from Munc13-4-deficient Jinx mice. Mobility studies using total internal reflection fluorescence microscopy indicate that Munc13-4 and Munc13-1 are responsible for the priming process of LGs. Furthermore, the domains of the Munc13 protein, which is responsible for functional fusion, could be identified. We conclude from these data that both isoforms of the Munc13 family, Munc13-1 and Munc13-4, are functionally redundant in murine CTLs.
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| 14. |
- Grotz, Joel, et al.
(författare)
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Applicability Of Interference Processing To DTH Reception
- 2006
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Ingår i: Ninth International Workshop on Signal Processing for Space Communications, September 2006.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Today fixed satellite broadcast reception has to compete efficiently with other means of broadcast content delivery to end-users. The ease of reception is essential to maintain a high penetration rate under more competitive conditions. The introduction of DVB-S2 increases efficiency and allows for a higher throughput or a reduction of the reception equipment requirements. This means that a robust broadcast reception is conceivable with a reduced direct-to-home (DTH) antenna size. The current interference situation at common geostationary broadcast positions dictates the spatial discrimination requirements of common direct-to-home (DTH) reception antennas. A more robust coding rate or a relaxation of the frequency coordination constraints would obviously relax the requirements on the reception front-end but only at the expense of a reduced aggregate efficiency. The use of known interference processing schemes for DTH reception has been investigated under dual reception path scenarios, see [1]. The present work extends the concept by introducing linear pre-processing (LPP) to combine coherent reception paths. These mechanisms will only be practical if the transmitted broadcast signals are compliant with established standards (ie. DVB-S [5] or DVB-S2 [4]). The maximization of the efficiency is a main objective under given reception environments. We show how multi-user detection techniques can increase efficiency and allow reduced antenna size under realistic conditions.
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| 15. |
- Grotz, Joel, et al.
(författare)
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Data-aided frequency synchronization under interference limited conditions
- 2005
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Ingår i: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE. - : IEEE. ; , s. 2683-2686
-
Konferensbidrag (refereegranskat)abstract
- Data-aided multi-user burst frequency synchronization under interference limited conditions is analyzed. It is assumed that a unique-word based synchronization mechanism is used to achieve synchronization. In a first approach this unique-word is assumed to be located at the beginning of the burst structure. The interference represents frequency-adjacent bursts that are coarsely time synchronous. This corresponds to a typical multi frequency (MF) TDMA system with co-channel interference (CCI) limited minimal frequency separation. A novel approach is analyzed to reduce the interference impact of the carrier offset estimation, applying interference cancellation iteratively to increase the estimation accuracy. We demonstrate improved frequency synchronization with this novel approach of iterative burst synchronization.
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| 16. |
- Grotz, Joel, et al.
(författare)
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Decision-directed interference cancellation applied to satellite broadcast reception : 2005 IEEE 62ND VEHICULAR TECHNOLOGY CONFERENCE, 1-4, PROCEEDINGS
- 2005
-
Ingår i: VTC2005-FALL. ; , s. 903-906
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the usage of established interference cancellation techniques applied to the simultaneous reception of geostationary satellite broadcast signals from two or more satellites. In particular the reduction of interference from adjacent satellites is of interest, which would allow a reduction of the antenna size and the requirements on the directivity of the installation. The rejection of unwanted adjacent satellite interferers can imply a large equivalent parabolic reflector size to achieve the required spatial separation of the signals. The usage of small and cheap reception antennas at the end-user premises can be facilitated by the reduction of the requirements on the antenna characteristics in terms of adjacent satellite interference rejection, in particular for the joint reception of signals from two or more simultaneous geostationary orbital locations. In this study the novel approach of using simple decision directed interference reduction techniques at the symbol detection level is considered to relax the requirements on the reception system front-end.
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| 17. |
- Grotz, Joel, et al.
(författare)
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Joint channel synchronization under interference limited conditions
- 2007
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Ingår i: IEEE Transactions on Wireless Communications. - : IEEE. - 1536-1276 .- 1558-2248. ; 6:10, s. 3781-3789
-
Tidskriftsartikel (refereegranskat)abstract
- Spectral efficiency is of great concern in the return channel of satellite based broadband systems. In [1] the feasibility of increased efficiency by reducing channel spacing below the Symbol Rate was demonstrated using joint detection and decoding for a synchronized system. We extend this work by addressing the critical synchronization problem in the presence of adjacent channel interference (ACI) which limits performance as carrier spacing is reduced. A pilot sequence aided joint synchronization scheme for a multi-frequency time division multiple access (MF-TDMA) system is proposed. Based on a maximum likelihood (ML) criterion, the channel parameters, including frequency, time and phase are jointly estimated for the channel of interest and the adjacent channels. The impact of ACI on the synchronization and detection performance is investigated. It is shown that joint channel parameter estimation outperforms single carrier synchronization with reasonable additional computational complexity in the receiver. Based on the proposed synchronization scheme in conjunction with an appropriate joint detection mechanism, see [1], carrier spacing can be reduced significantly compared to current systems providing a substantial increase in spectral efficiency.
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| 18. |
- Grotz, Joel, et al.
(författare)
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Signal Detection and Synchronization for Interference Overloaded Satellite Broadcast Reception
- 2010
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Ingår i: IEEE Transactions on Wireless Communications. - : IEEE. - 1536-1276 .- 1558-2248. ; 9:10, s. 3052-3063
-
Tidskriftsartikel (refereegranskat)abstract
- We address fixed satellite broadcast reception with the goal of decreasing the aperture of the receiving antenna. The front-end antenna size is commonly determined by the presence of interference from adjacent satellites. A small antenna aperture leads to interference from neighboring satellites utilizing the same frequency bands. We propose a reception system with. M multiple input elements and with subsequent joint detection of desired and interfering signals that provides reliable communication in the presence of multiple interfering signals. An iterative least squares technique is adopted combining spatial and temporal processing and achieving robustness against pointing errors. Simulation results show how the proposed joint spatial and temporal adapted mechanism outperforms the simple combination of existing techniques under interference overloaded conditions. Also, we demonstrate how to accurately synchronize the signals as part of the detection procedure. The technique is evaluated in a realistic simulation study representing the conditions encountered in a DVB-S2 broadcast scenario.
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| 19. |
- Halimani, Mahantappa, et al.
(författare)
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Syntaxin11 serves as a t-SNARE for the fusion of lytic granules in human cytotoxic T lymphocytes
- 2014
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 44:2
-
Tidskriftsartikel (refereegranskat)abstract
- CTLs kill target cells via fusion of lytic granules (LGs) at the immunological synapse (IS). Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) function as executors of exocytosis. The importance of SNAREs in CTL function is evident in the form of familial hemophagocytic lymphohistiocytosis type 4 that is caused by mutations in Syntaxin11 (Stx11), a Qa-SNARE protein. Here, we investigate the molecular mechanism of Stx11 function in primary human effector CTLs with high temporal and spatial resolution. Downregulation of endogenous Stx11 resulted in a complete inhibition of LG fusion that was paralleled by a reduction in LG dwell time at the IS. Dual color evanescent wave imaging suggested a sequential process, in which first Stx11 is transported to the IS through a subpopulation of recycling endosomes. The resulting Stx11 clusters at the IS then serve as a platform to mediate fusion of arriving LGs. We conclude that Stx11 functions as a t-SNARE for the final fusion of LG at the IS, explaining the severe phenotype of familial hemophagocytic lymphohistiocytosis type 4 on a molecular level.
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| 20. |
- Herbert-Read, James E., et al.
(författare)
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How predation shapes the social interaction rules of shoaling fish
- 2017
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 284:1861
-
Tidskriftsartikel (refereegranskat)abstract
- Predation is thought to shape the macroscopic properties of animal groups, making moving groups more cohesive and coordinated. Precisely how predation has shaped individuals' fine-scale social interactions in natural populations, however, is unknown. Using high-resolution tracking data of shoaling fish (Poecilia reticulata) from populations differing in natural predation pressure, we show how predation adapts individuals' social interaction rules. Fish originating from high predation environments formed larger, more cohesive, but not more polarized groups than fish from low predation environments. Using a new approach to detect the discrete points in time when individuals decide to update their movements based on the available social cues, we determine how these collective properties emerge from individuals' microscopic social interactions. We first confirm predictions that predation shapes the attraction-repulsion dynamic of these fish, reducing the critical distance at which neighbours move apart, or come back together. While we find strong evidence that fish align with their near neighbours, we do not find that predation shapes the strength or likelihood of these alignment tendencies. We also find that predation sharpens individuals' acceleration and deceleration responses, implying key perceptual and energetic differences associated with how individuals move in different predation regimes. Our results reveal how predation can shape the social interactions of individuals in groups, ultimately driving differences in groups' collective behaviour.
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| 21. |
- Khani, Sajjad, et al.
(författare)
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Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function
- 2024
-
Ingår i: Nature Metabolism. - 2522-5812.
-
Tidskriftsartikel (refereegranskat)abstract
- Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5′ truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation.
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| 22. |
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| 23. |
- Mann, Richard P., et al.
(författare)
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The dynamics of audience applause
- 2013
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 10:85, s. 20130466-
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Tidskriftsartikel (refereegranskat)abstract
- The study of social identity and crowd psychology looks at how and why individual people change their behaviour in response to others. Within a group, a new behaviour can emerge first in a few individuals before it spreads rapidly to all other members. A number of mathematical models have been hypothesized to describe these social contagion phenomena, but these models remain largely untested against empirical data. We used Bayesian model selection to test between various hypotheses about the spread of a simple social behaviour, applause after an academic presentation. Individuals' probability of starting clapping increased in proportion to the number of other audience members already 'infected' by this social contagion, regardless of their spatial proximity. The cessation of applause is similarly socially mediated, but is to a lesser degree controlled by the reluctance of individuals to clap too many times. We also found consistent differences between individuals in their willingness to start and stop clapping. The social contagion model arising from our analysis predicts that the time the audience spends clapping can vary considerably, even in the absence of any differences in the quality of the presentations they have heard.
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| 24. |
- Marras, Stefano, et al.
(författare)
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Not So Fast : Swimming Behavior of Sailfish during Predator-Prey Interactions using High-Speed Video and Accelerometry
- 2015
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 55:4, s. 719-727
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Tidskriftsartikel (refereegranskat)abstract
- Synopsis Billfishes are considered among the fastest swimmers in the oceans. Despite early estimates of extremely high speeds, more recent work showed that these predators (e.g., blue marlin) spend most of their time swimming slowly, rarely exceeding 2 m s(-1). Predator-prey interactions provide a context within which one may expect maximal speeds both by predators and prey. Beyond speed, however, an important component determining the outcome of predator-prey encounters is unsteady swimming (i.e., turning and accelerating). Although large predators are faster than their small prey, the latter show higher performance in unsteady swimming. To contrast the evading behaviors of their highly maneuverable prey, sailfish and other large aquatic predators possess morphological adaptations, such as elongated bills, which can be moved more rapidly than the whole body itself, facilitating capture of the prey. Therefore, it is an open question whether such supposedly very fast swimmers do use high-speed bursts when feeding on evasive prey, in addition to using their bill for slashing prey. Here, we measured the swimming behavior of sailfish by using high-frequency accelerometry and high-speed video observations during predator-prey interactions. These measurements allowed analyses of tail beat frequencies to estimate swimming speeds. Our results suggest that sailfish burst at speeds of about 7 m s(-1) and do not exceed swimming speeds of 10 m s(-1) during predator-prey interactions. These speeds are much lower than previous estimates. In addition, the oscillations of the bill during swimming with, and without, extension of the dorsal fin (i.e., the sail) were measured. We suggest that extension of the dorsal fin may allow sailfish to improve the control of the bill and minimize its yaw, hence preventing disturbance of the prey. Therefore, sailfish, like other large predators, may rely mainly on accuracy of movement and the use of the extensions of their bodies, rather than resorting to top speeds when hunting evasive prey.
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| 25. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
-
Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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