The development of structure and function in chloroplasts of greening mutants of Scenedesmus IV. Blue light-dependent carbohydrate and protein metabolism

Pigment mutant C-2A' of Scenedesmus obliquus forms only tracesof chlorophyll when grown heterotrophically in the dark. Thechloroplast shows pre-thylakoid structures and a high Contentof starch grains. Illumination causes a sequence of reactionsleading, finally, to chloroplasts with normal thylakoids andan efficiently functioning photosynthetic apparatus. Upon illumination the respiration of the cells is enhanced,starch is degraded and protein is synthesized. The newly-formedprotein in turn is used for formation of enzyme(s) leading tothe synthesis of -aminolevulinic acid, of structural proteinsin the thylakoid membranes and finally to the chlorophyll holochrome.Most of the newly-synthesized protein becomes part of the thylakoidmembranes. All these processes are strictly blue light-dependent. The blue light phenomena can be separated into two groups onthe basis of small wavelength shifts and of their energy requirement.Enhancement of respiration and starch degradation are saturatedat low energy (0.4 w/m² whereas the subsequent protein synthesisand following processes are saturated at high energy (100 w/m²) From the wavelength dependence of the reactions we conclude,in accordance with other authors, that flavoproteins are theprimary photoreceptors. The possibility that the primary lowenergy process might excite a flavoprotein which in turn causesa conformational change in its apoprotein, and that the highenergy process might present a direct energy transduction viaa flavoprotein is discussed. (Received May 10, 1978; )     

Der Buntsandstein. Eine lebensfeindliche Wüste oder doch mehr?

A hostile desert – or still more? The Bunter During the time span of the Bunter a continental, semiarid to arid climate with high temperatures prevailed in the “Germanic Basin”. The sediments deposited are often “coloured” – mostly red – because of the oxidizing conditions. They mostly represent braided river systems and large flood plains. In the Upper Bunter a connection to the Tethys sea existed. The evaporation of salt water led to the formation of thick layers of hydrogenetic rocks in the Early Upper Bunter. Palynomorphs and the famous fossil communities found are providing evidence of life and climate during the Bunter period.     

Natural antiviral compound silvestrol modulates human monocyte‐derived macrophages and dendritic cells

Outbreaks of infections with viruses like Sars‐CoV‐2, Ebola virus and Zika virus lead to major global health and economic problems because of limited treatment options. Therefore, new antiviral drug candidates are urgently needed. The promising new antiviral drug candidate silvestrol effectively inhibited replication of Corona‐, Ebola‐, Zika‐, Picorna‐, Hepatis E and Chikungunya viruses. Besides a direct impact on pathogens, modulation of the host immune system provides an additional facet to antiviral drug development because suitable immune modulation can boost innate defence mechanisms against the pathogens. In the present study, silvestrol down‐regulated several pro‐ and anti‐inflammatory cytokines (IL‐6, IL‐8, IL‐10, CCL2, CCL18) and increased TNF‐α during differentiation and activation of M1‐macrophages, suggesting that the effects of silvestrol might cancel each other out. However, silvestrol amplified the anti‐inflammatory potential of M2‐macrophages by increasing expression of anti‐inflammatory surface markers CD206, TREM2 and reducing release of pro‐inflammatory IL‐8 and CCL2. The differentiation of dendritic cells in the presence of silvestrol is characterized by down‐regulation of several surface markers and cytokines indicating that differentiation is impaired by silvestrol. In conclusion, silvestrol influences the inflammatory status of immune cells depending on the cell type and activation status.     

A tissue-specific marker of Ecdysozoa

Over the past few years, molecular studies of phylogeny have challenged the traditional view of evolutionary relationships among protostomian animal phyla. Based on analysis of 18S ribosomal RNA gene sequences, it has been suggested that some traditional groups, like the articulata and the pseudocoelomata, should be completely abandoned and that instead the protostomians should be split into two major clades: the Ecdysozoa and the Lophotrochozoa. However, this new molecular phylogeny still awaits confirmation by independent methods. In this study, we present a cytological feature that supports the new classification. The carbohydrate epitope that is recognised by antisera against the plant glycoprotein horseradish peroxidase (HRP) is known to be selectively expressed by membrane proteins on the surface of neural tissue in insects. We found that the major ecdysozoan phyla show neural expression of HRP immunoreactivity, which is completely absent in the nervous tissue of lophotrochozoans, deuterostomians, and cnidarians. This suggests that the presence of anti-HRP-reactive glycoproteins in neural tissue is an ecdysozoan autapomorphy.     

Chemo-somatosensory evoked potentials: A sensitive tool to assess conditioned pain modulation?

Background: Chemo-somatosensory evoked potentials (CSSEPs) elicited by chemical stimulation (CO₂ gas) of the nasal mucosa have been shown to be sensitive enough to pick up even weak analgesic effects. With the present study we wanted to investigate whether CSSEPs are also a sensitive tool to capture endogenous pain inhibitory mechanisms elicited by conditioned pain modulation (CPM; where a first conditioning stimulus reduces the sensitivity for a second test stimulus) with a conditioning stimulus of rather low noxious load.

Methods: Seventeen healthy participants were tested for CPM effects (conditioning stimulus: tonic heat pain with intensities around the pain threshold induced via a thermode; test stimulus: chemonasal stimulation (73% and 78% CO₂)) on CSSEPs and on self-report ratings.

Results: We found significant CPM effects in the CSSEPS, with reduced amplitudes and prolonged latencies at several electroencephalogram (EEG) recording positions when using the lower CO₂ concentration (73% CO₂). In contrast to the visible inhibitory effects on the CSSEPs, subjective ratings of the test stimulus did not reflect CPM action.

Discussion: The experimental pain model using CO₂ stimuli to elicit CSSEPs proved to be sensitive enough to capture weak CPM effects elicited by a conditioning stimulus of rather low noxious load. The usage of such mild noxious conditioning stimuli—in contrast to stimuli of higher noxious load (e.g., cold pressor test)—has the advantage that the activation of other types of pain inhibitory mechanisms in parallel (like attentional distraction, stress-induced analgesia) can be avoided.