Rapid colour changes in Euglena sanguinea (Euglenophyceae) caused by internal lipid globule migration

The accumulation of red pigments under chronic stress is a response observed in most groups of oxygenic photoautotrophs. It is thought that the red pigments in the cell shield the chlorophyll located underneath from the light. Among these red pigments, the accumulation of carotenoids is one of the most frequent cases. However, the synthesis or degradation of carotenoids is a slow process and this response is usually only observed when the stress is maintained over a period of time. In the Euglenophyte Euglena sanguinea, this is due to the accumulation of a large amount of free and esterified astaxanthin (representing 80% of the carotenoid pool). While reddening is a slow and sometimes irreversible process in other phototrophs, reducing the efficiency of light harvesting by chlorophyll, in E. sanguinea it is highly dynamic, capable of shifting from red to green (and vice-versa) in 10-20 min. This change is not due to de novo carotenogenesis, but to the relocation of cytoplasmic lipid globules where astaxanthin accumulates. Thus, red globules migrate from the centre of the cell to peripheral locations when photoprotection is demanded. This protective system seems to be so efficient that other classical mechanisms are not operative in this species. For example, despite the presence and operation of the diadino-diatoxanthin cycle, nonphotochemical quenching (NPQ) is almost undetectable. Since E. sanguinea forms extensive floating colonies, reddening can be observed at much greater scale than at a cellular level, the mechanism described here being one of the fastest and most dramatic colour changes attributable to photosynthetic organisms at cell and landscape level. In sum, these data indicate an extremely dynamic and efficient photoprotective mechanism based on organelle migration more than on carotenoid biosynthesis that prevents excess light absorption by chlorophylls reducing the need for other protective processes related to energy dissipation.This work was supported by the Basque Government [UPV/EHU-GV IT-1018-16] [UPV/EHU PPG17/67 – GV IT-1040-16], and by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Research and Development Foundation (FEDER) through (i) [CTM2014-53902-C2-2-P] national grant and (ii) a “Juan de la Cierva-Incorporación” postdoctoral grant [IJCI-2014-22489] to BFM

Effects of insoluble cereal fibre on body fat distribution in the optimal fibre trial

Scope: The Optimal Fibre Trial (OptiFiT) investigates metabolic effects of insoluble cereal fibre in subjects with impaired glucose tolerance (IGT), showing moderate glycemic and anti-inflammatory benefits, especially in subjects with an obesity-related phenotype. An OptiFiT sub-group is analysed for effects on body fat distribution. Methods and results: 180 participants with IGT receive a blinded, randomized supplementation with insoluble cereal fibre or placebo for 2 years. Once a year, all subjects undergo fasting blood sampling, oral glucose tolerance test, and anthropometric measurements. A subgroup (n=47) also received magnetic resonance imaging and spectroscopy for quantification of adipose tissue distribution and liver fat content. We compared MR, metabolic and inflammatory outcomes between fibre and placebo group metabolism and inflammation. Visceral and non-visceral fat, fasting glucose, HbA1c, fasting insulin, insulin resistance, and uric acid decrease only in the fibre group, mirroring effects of the entire cohort. However, after adjustment for weight loss, there are no significant between-group differences. There is a statistical trend for fibre-driven liver fat reduction in subjects with confirmed non-alcoholic fatty liver disease (NAFLD; n = 19). Conclusions: Data and evidence on beneficial effects of insoluble cereal fibre on visceral and hepatic fatstorage is limited, but warrants further research. Targeted trials are required

The role of the anterior intraparietal sulcus in crossmodal processing of object features in humans: An rTMS study

Investigations in macaques and humans have shown that the anterior intraparietal sulcus (IPS) has an important function in the integration of information from tactile and visual object manipulation. The goal of this study was to investigate the special functional role of the anterior IPS in visuo-tactile matching in humans. We used the "virtual-lesion" technique of repetitive transcranial magnetic stimulation (rTMS) to test the functional relevance of anterior IPS for visuo-tactile crossmodal matching. Two crossmodal (visual encoding and tactile recognition and vice versa) and two unimodal delayed matching-to-sample tests with geometrical patterns were performed by 12 healthy subjects. We determined error rates before and after focal low-frequency rTMS applied over the left anterior IPS, right anterior IPS and vertex. During the manipulation of objects with the right hand, rTMS over the left anterior IPS induced a significant deterioration for visual encoding and tactile recognition, but not for tactile encoding and visual recognition. For the visual and tactile unimodal conditions, no significant alterations in task performance were found. rTMS application over right IPS when manipulating objects with the left hand did not affect crossmodal task performance. In conclusion, we have demonstrated an essential functional role of the left anterior IPS for visuo-tactile matching when manipulating objects with the right hand. However, we found no clear evidence for left IPS involvement in tactile encoding and visual recognition. The differential effect of rTMS on tactile and visual encoding and recognition are not consistently explained by previous concepts of visuo-tactile integration

Predictive effect of GIPR SNP rs10423928 on glucose metabolism liver fat and adiposity in prediabetic and diabetic subjects.

The gastric inhibitory polypeptide receptor (GIPR) regulates postprandial metabolism. In this context GIPR SNP rs10423928 seems toplay an important role in modulating glucose metabolism and insulinsensitivity. However, evidence regarding thisparticular SNP is still vague.In this study, we collected baseline data from four different dietaryintervention studies. We genotyped 424 subjects with prediabetes and 73with diabetes for GIPR SNP rs10423928 and examined its impact on glucosemetabolism, insulin sensitivity and body fat accumulation.We extended previous data by showing that carriers of the A allele withprediabetes displayed increased fasting glucose (p = 0.015). Unexpectedly,A allele carriers showed lower glucose levels 2 h (p = 0.021) after anoral glucose challenge compared to T/T homozygous individuals. A allelecarriers also showed significantly higher insulin sensitivity (p < 0.001)(assessed by Cederholm Index), indicating an enhanced beta-cell response.This study points to a potential protective role for rs10423928 inglucose metabolism and insulin sensitivity in subjects with prediabetes.Further studies are necessary to confirm these results

Holocene fluviatile processes and valley history in the river Rhine catchment

Eine Detailuntersuchung des Rheineinzugsgebietes erbrachte ein System der fluviatilen Fazies (die "Fluviatile Serie"), der Struktur, der texturellen Anordnung fluviatiler Terrassenkörper und unterschiedliche Terrassenmuster. Der Talgrund erweist sich als durch zehn fluviatile Akkumulationsphasen gestaltet, drei oberwürmzeitliche und sieben holozäne. Zeitgleiche Phasen fluviatiler Aktivität und Ruhe an großen und kleinen Flüssen belegen klimatische Steuerung. Die Ruhephasen werden nicht nur aus still werdender Sedimentation ersichtlich, sondern auch aus fossilen Böden, die die Auensedimentdecken verschiedener fluviatiler Serien trennen. Regionale Prägung durch die individuellen Flusseinzugsgebiete beeinflussen Textur, Terrassenmuster, Innenaufbau und typologische Auenbodenprägung der Terrassenabfolgen. Menschliche Einflussnahme modifiziert seit dem Neolithikum zunehmend die natürlichen talformenden Prozesse, wie Feinsedimenteintrag in die Auen seit dem Atlantikum, deutliche Auenverbreiterung seit Beginn des Subatlantikums, Flussbettverflachung mit Tendenz zur Verzweigung seit dem Frühmittelalter, Kanalisierung des Flussbetts und Umgestaltung der Aue seit dem Verlauf des 19. Jahrhunderts. Dennoch bleibt neben anthropogener Überprägung die natürliche Steuerung die Haupttriebfeder fluviatiler Aktivität und bleibt als solche deutlich sichtbar. Erste Versuche der Budgetierung der Sedimentflussraten von einzelnen Zeitausschnitten der drei Perioden, der glazialen, der waldholozänen und kulturholozänen Perioden, sind dem Text in drei Fallbeispielen angefügt, die nach Zeitauflösung und Raum noch bescheiden sind: das Rheindelta im oberen Bodensee, das zum unteren Neckar gehörige Elsenz-Einzugsgebiet nahe Heidelberg und ein Ausschnitt des Siebengebirgsgehänges gegen den Rhein. /// A detailed investigation of the River Rhine catchment resulted in a system of the fluvial facies (the "fluvial series"), the structure and the texture of fluviatile terrace bodies and different terrace patterns. The valley bottom is formed by ten fluvial accumulation phases, three of upper Würmian age and seven of Holocene age. Synchronous phases of alternating increased fluvial activity and quiescence on major and smaller rivers give proof of climatic control over the fluvial rhythmicity. The quiescence phases are not only marked by a retreat of the river sedimentation but also by fossil soils that are separating flood loam veneers of the individual fluviatile series. Local forming of the valley ground by the individual river catchment does affect the texture, pattern, structure and floodplain soil types of the terrace sequences. Man's impact since the Neolithic period modifies increasingly the natural valley-forming processes: input of fines into the floodplain since the Atlantic period, essential widening of the floodplain since the beginning of the Subatlantic period, flattening of the channel with a tendency to braiding since the early Middle Ages, canalising of the channel and remodelling of the floodplain since the course of the 19th century. But despite human modification, the natural imprints are dominating and remain visible. A first small onset of budgeting of the sediment flux rates of parts of the three periods, the glacial, the natural Holocene and the human Holocene periods, is shown by three case studies still rather restricted in space and resolution of time: the Rhine delta within the Lake Constance, the Elsenz catchment as a Neckar tributary close to Heidelberg and a versant area in the Siebengebirge directed towards the River Rhine

Sensory Axon growth requires spatiotemporal integration of CaSR and TrkB Signaling

Neural circuit development involves the coordinated growth and guidance of axons. During this process, axons encounter many different cues, but how these cues are integrated and translated into growth is poorly understood. In this study, we report that receptor signaling does not follow a linear path but changes dependent on developmental stage and coreceptors involved. Using developing chicken embryos of both sexes, our data show that calcium-sensing receptor (CaSR), a G-protein-coupled receptor important for regulating calcium homeostasis, regulates neurite growth in two distinct ways. First, when signaling in isolation, CaSR promotes growth through the PI3-kinase-Akt pathway. At later developmental stages, CaSR enhances tropomyosin receptor kinase B (TrkB)/BDNF-mediated neurite growth. This enhancement is facilitated through a switch in the signaling cascade downstream of CaSR (i.e., from the PI3-kinase-Akt pathway to activation of GSK3α Tyr279). TrkB and CaSR colocalize within late endosomes, cotraffic and coactivate GSK3, which serves as a shared signaling node for both receptors. Our study provides evidence that two unrelated receptors can integrate their individual signaling cascades toward a nonadditive effect and thus control neurite growth during development. SIGNIFICANCE STATEMENT This work highlights the effect of receptor coactivation and signal integration in a developmental setting. During embryonic development, neurites grow toward their targets guided by cues in the extracellular environment. These cues are sensed by receptors at the surface that trigger intracellular signaling events modulating the cytoskeleton. Emerging evidence suggests that the effects of guidance cues are diversified, therefore expanding the number of responses. Here, we show that two unrelated receptors can change the downstream signaling cascade and regulate neuronal growth through a shared signaling node. In addition to unraveling a novel signaling pathway in neurite growth, this research stresses the importance of receptor coactivation and signal integration during development of the nervous system