The invasive crayfish Faxonius immunis causes the collapse of macroinvertebrate communities in Central European ponds

Aquatic Ecology - The invasive crayfish Faxonius immunis is regarded as a threat to amphibians and macroinvertebrates in the Upper Rhine Valley, Germany, eradicating macrophytes and establishing...     

Water availability shapes edaphic and lithic cyanobacterial communities in the Atacama Desert

In the Atacama Desert, cyanobacteria grow on various substrates such as soils (edaphic) and quartz or granitoid stones (lithic). Both edaphic and lithic cyanobacterial communities have been described but no comparison between both communities of the same locality has yet been undertaken. In the present study, we compared both cyanobacterial communities along a precipitation gradient ranging from the arid National Park Pan de Azúcar (PA), which resembles a large fog oasis in the Atacama Desert extending to the semiarid Santa Gracia Natural Reserve (SG) further south, as well as along a precipitation gradient within PA. Various microscopic techniques, as well as culturing and partial 16S rRNA sequencing, were applied to identify 21 cyanobacterial species; the diversity was found to decline as precipitation levels decreased. Additionally, under increasing xeric stress, lithic community species composition showed higher divergence from the surrounding edaphic community, resulting in indigenous hypolithic and chasmoendolithic cyanobacterial communities. We conclude that rain and fog water, respectively, cause contrasting trends regarding cyanobacterial species richness in the edaphic and lithic microhabitats.     

Regulation of autophagy as a therapy for immunosenescence-driven cancer and neurodegenerative diseases: The role of exercise

Aging is one of the risk factors for the development of low-grade inflammation morbidities, such as several types of cancer and neurodegenerative diseases, due to changes in the metabolism, hormonal secretion, and immunosenescence. The senescence of the immune system leads to improper control of infections and tissue damage increasing age-related diseases. One of the mechanisms that maintain cellular homeostasis is autophagy, a cell-survival mechanism, and it has been proposed as one of the most powerful antiaging therapies. Regular exercise can reestablish autophagy, probably through AMP-activated protein kinase activation, and help in reducing the age-related senescence diseases. Therefore, in this study, we discuss the effects of exercise training in immunosenescence and autophagy, preventing the two main age-related disease, cancer and neurodegeneration.     

Virus-related Knowledge in Covid-19 Times - Results from two Cross-sectional Studies in Austria and Implications for School

Viruses have become a prominent issue in public health, politics and economics due to the Covid-19 pandemic. Yet they have still met little attention in educational research, although misconceptions concerning viruses may contribute to antibiotics misuse, disbelief in existence of viruses and distrust in vaccination. We investigated knowledge and attitudes in Austria concerning Covid-19, viruses in general and vaccination. We conducted two cross-sectional online surveys. Study A was performed Austrian-wide (N = 1027), study B specifically targeted Austrian students from middle and high schools (N = 1728). Several participants did not believe in the existence of SARS-CoV-2. General vaccination damage was highly overrated. Many defined viruses as unicellular organisms or bacteria, and 6-10 % believed that they can be killed by antibiotics. Very many participants were unable to identify, whether a specific disease was caused by a virus or another pathogen. Knowledge was significantly correlated with level of education/grade and interest in virology. Additionally, willingness to become vaccinated was significantly correlated with knowledge. Many participants felt insufficiently informed about viruses at school. We strongly recommend that virus-related school education must highly improve to enable the population to correctly assess health-related information, counter fake news and come to scientifically informed decisions.     

Splicing factor SRp30c interaction with Y-box protein-1 confers nuclear YB-1 shuttling and alternative splice site selection

The multifunctional DNA- and RNA-associated Y-box protein 1 (YB-1) specifically binds to splicing recognition motifs and regulates alternative splice site selection. Here, we identify the arginine/serine-rich SRp30c protein as an interacting protein of YB-1 by performing a two-hybrid screen against a human mesangial cell cDNA library. Co-immunoprecipitation studies confirm a direct interaction of tagged proteins YB-1 and SRp30c in the absence of RNA via two independent protein domains of YB-1. A high affinity interaction is conferred through the N-terminal region. We show that the subcellular YB-1 localization is dependent on the cellular SRp30c content. In proliferating cells, YB-1 localizes to the cytoplasm, whereas FLAG-SRp30c protein is detected in the nucleus. After overexpression of YB-1 and FLAG-SRp30c, both proteins are co-localized in the nucleus, and this requires the N-terminal region of YB-1. Heat shock treatment of cells, a condition under which SRp30c accumulates in stress-induced Sam68 nuclear bodies, abrogates the co-localization and YB-1 shuttles back to the cytoplasm. Finally, the functional relevance of the YB-1/SRp30c interaction for in vivo splicing is demonstrated in the E1A minigene model system. Here, changes in splice site selection are detected, that is, overexpression of YB-1 is accompanied by preferential 5' splicing site selection and formation of the 12 S isoform.     

Sinorhizobium meliloti acpXL mutant lacks the C28 hydroxylated fatty acid moiety of lipid A and does not express a slow migrating form of lipopolysaccharide

Lipid A is the hydrophobic anchor of lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria. Lipid A of all Rhizobiaceae is acylated with a long fatty acid chain, 27-hydroxyoctacosanoic acid. Biosynthesis of this long acyl substitution requires a special acyl carrier protein, AcpXL, which serves as a donor of C28 (omega-1)-hydroxylated fatty acid for acylation of rhizobial lipid A (Brozek, K.A., Carlson, R.W., and Raetz, C. R. (1996) J. Biol. Chem. 271, 32126-32136). To determine the biological function of the C28 acylation of lipid A, we constructed an acpXL mutant of Sinorhizobium meliloti strain 1021. Gas-liquid chromatography and mass spectrometry analysis of the fatty acid composition showed that the acpXL mutation indeed blocked C28 acylation of lipid A. SDS-PAGE analysis of acpXL mutant LPS revealed only a fast migrating band, rough LPS, whereas the parental strain 1021 manifested both rough and smooth LPS. Regardless of this, the LPS of parental and mutant strains had a similar sugar composition and exposed the same antigenic epitopes, implying that different electrophoretic profiles might account for different aggregation properties of LPS molecules with and without a long acyl chain. The acpXL mutant of strain 1021 displayed sensitivity to deoxycholate, delayed nodulation of Medicago sativa, and a reduced competitive ability. However, nodules elicited by this mutant on roots of M. sativa and Medicago truncatula had a normal morphology and fixed nitrogen. Thus, the C28 fatty acid moiety of lipid A is not crucial, but it is beneficial for establishing an effective symbiosis with host plants. acpXL lies upstream from a cluster of five genes, including msbB (lpxXL), which might be also involved in biosynthesis and transfer of the C28 fatty acid to the lipid A precursor.     

B cell developmental requirement for the G alpha i2 gene

Null mutation of the Galphai2 trimeric G protein results in a discrete and profound mucosal disorder, including inflammatory bowel disease (IBD), attenuation of IL-10 expression, and immune function polarized to Th1 activity. Genetic and adoptive transfer experiments have established a role for B cells and IL-10 in mucosal immunologic homeostasis and IBD resistance. In this study, we addressed the hypothesis that Galphai2 is required for the development of IL-10-producing B cells. Galphai2(-/-) mice were reduced in the relative abundance of marginal zone (MZ), transitional type 2 (T2), and B-1a B cells and significantly increased in follicular mature and B-1b B cells. Reconstitution of RAG2(-/-) mice with Galphai2(-/-) bone marrow induced an IBD-like colitis and a deficiency in absolute numbers of MZ, T2, and B-1 B cells. Thus, the Galphai2(-/-) genotype in colitis susceptibility and B cell development involved a cis effect within the hemopoietic compartment. In vitro, the B cell population of Galphai2(-/-) mice was functionally deficient in LPS-induced proliferation and IL-10 production, consistent with the exclusive capacity of T2 and MZ cell subpopulations for LPS responsiveness. In vivo, Galphai2(-/-) mice were selectively impaired for the IgM response to T-independent type II, consistent with the relative depletion of MZ and peritoneal B-1 subpopulations. Collectively, these results reveal a selective role for Galphai2 in MZ and B-1 B cell development. Disorders of this Galphai2-dependent process in B cell development may represent a mechanism for IBD susceptibility.     

The plastidic pentose phosphate translocator represents a link between the cytosolic and the plastidic pentose phosphate pathways in plants

Plastids are the site of the reductive and the oxidative pentose phosphate pathways, which both generate pentose phosphates as intermediates. A plastidic transporter from Arabidopsis has been identified that is able to transport, in exchange with inorganic phosphate or triose phosphates, xylulose 5-phosphate (Xul-5-P) and, to a lesser extent, also ribulose 5-phosphate, but does not accept ribose 5-phosphate or hexose phosphates as substrates. Under physiological conditions, Xul-5-P would be the preferred substrate. Therefore, the translocator was named Xul-5-P/phosphate translocator (XPT). The XPT shares only approximately 35% to 40% sequence identity with members of both the triose phosphate translocator and the phosphoenolpyruvate/phosphate translocator classes, but a higher identity of approximately 50% to glucose 6-phosphate/phosphate translocators. Therefore, it represents a fourth group of plastidic phosphate translocators. Database analysis revealed that plant cells contain, in addition to enzymes of the oxidative branch of the oxidative pentose phosphate pathway, ribose 5-phosphate isomerase and ribulose 5-phosphate epimerase in both the cytosol and the plastids, whereas the transketolase and transaldolase converting the produced pentose phosphates to triose phosphates and hexose phosphates are probably solely confined to plastids. It is assumed that the XPT function is to provide the plastidic pentose phosphate pathways with cytosolic carbon skeletons in the form of Xul-5-P, especially under conditions of a high demand for intermediates of the cycles.     

Spatiotemporal Correlations between Cytosolic and Mitochondrial Ca2+ Signals Using a Novel Red-Shifted Mitochondrial Targeted Cameleon

The transfer of Ca²⁺ from the cytosol into the lumen of mitochondria is a crucial process that impacts cell signaling in multiple ways. Cytosolic Ca²⁺ ([Ca²⁺]_cyto) can be excellently quantified with the ratiometric Ca²⁺ probe fura-2, while genetically encoded Förster resonance energy transfer (FRET)-based fluorescent Ca²⁺ sensors, the cameleons, are efficiently used to specifically measure Ca²⁺ within organelles. However, because of a significant overlap of the fura-2 emission with the spectra of the cyan and yellow fluorescent protein of most of the existing cameleons, the measurement of fura-2 and cameleons within one given cell is a complex task. In this study, we introduce a novel approach to simultaneously assess [Ca²⁺]_cyto and mitochondrial Ca²⁺ ([Ca²⁺]_mito) signals at the single cell level. In order to eliminate the spectral overlap we developed a novel red-shifted cameleon, D1GO-Cam, in which the green and orange fluorescent proteins were used as the FRET pair. This ratiometric Ca²⁺ probe could be successfully targeted to mitochondria and was suitable to be used simultaneously with fura-2 to correlate [Ca²⁺]_cyto and [Ca²⁺]_mito within same individual cells. Our data indicate that depending on the kinetics of [Ca²⁺]_cyto rises there is a significant lag between onset of [Ca²⁺]_cyto and [Ca²⁺]_mito signals, pointing to a certain threshold of [Ca²⁺]_cyto necessary to activate mitochondrial Ca²⁺ uptake. The temporal correlation between [Ca²⁺]_mito and [Ca²⁺]_cyto as well as the efficiency of the transfer of Ca²⁺ from the cytosol into mitochondria varies between different cell types. Moreover, slow mitochondrial Ca²⁺ extrusion and a desensitization of mitochondrial Ca²⁺ uptake cause a clear difference in patterns of mitochondrial and cytosolic Ca²⁺ oscillations of pancreatic beta-cells in response to D-glucose.