Method-integrated fish assemblage structure at two spatial scales along a free-flowing stretch of the Austrian Danube

Fish assemblages in large rivers are highly diverse communities. However, a single method to describe these complex systems adequately is not available as of yet. In this paper we propose a combination of normalized catch-per-unit-effort data of three fish sampling methods, thus providing a more inclusive representation of the overall assemblage. We investigate fish species occurrence and abundance in a survey at three consecutive sites in the free-flowing main channel of the Austrian Danube east of Vienna. Using boat and wading electrofishing, as well as longline fishing we collected data in four mesohabitats at each site. We analysed richness, assemblage structure and abundance of single species and tested site and mesohabitat as differentiating forces on the fish assemblage structure, applying PERMANOVA and NMDS. The investigated sites are populated by a species-rich fish assemblage, of which we collected a total of 36 species. The composition of the assemblage was rather consistent except for the occasional occurrence of rare species. At the smaller mesohabitat scale, however, the assemblages differed considerably and hydromorphological conditions were apparently the major structuring force. Overall, the combination of methods considerably improves the assessment across sites and mesohabitats and contributes to our understanding of large river fish assemblages.     

Cortical‐layer‐specific effects of PACAP and tPA on interneuron migration during post‐natal development of the cerebellum

During early post‐natal development of the cerebellum, granule neurons (GN) execute a centripetal migration toward the internal granular layer, whereas basket and stellate cells (B/SC) migrate centrifugally to reach their final position in the molecular layer (ML). We have previously shown that pituitary adenylate cyclase‐activating polypeptide (PACAP) stimulates in vitro the expression and release of the serine protease tissue‐type plasminogen activator (tPA) from GN, but the coordinated role of PACAP and tPA during interneuron migration has not yet been investigated. Here, we show that endogenous PACAP is responsible for the transient arrest phase of GN at the level of the Purkinje cell layer (PCL) but has no effect on B/SC. tPA is devoid of direct effect on GN motility in vitro, although it is widely distributed along interneuron migratory routes in the ML, PCL, and internal granular layer. Interestingly, plasminogen activator inhibitor 1 reduces the migration speed of GN in the ML and PCL, and that of B/SC in the ML. Taken together, these results reveal for the first time that tPA facilitates the migration of both GN and fast B/SC at the level of their intersection in the ML through degradation of the extracellular matrix.

     

Indigenous demosponge spicules in a Late Devonian stromatoporoid basal skeleton from the Frasnian of Belgium

This paper records the first example of a demosponge spicule framework in a single specimen of a Devonian stromatoporoid from the Frasnian of southern Belgium. The small sample (2.5 × 2 cm) is a component in a brecciated carbonate from a carbonate mound in La Boverie Quarry 30 km east of Dinant. Because of the small size of the sample, generic identification is not confirmed, but the stromatoporoid basal skeleton is similar to the genus Stromatopora. The spicules are arranged in the calcified skeleton, but not in the gallery space, and are recrystallized as multi‐crystalline calcite. The spicules fall into two size ranges: 10–20 μm diameter and 500–2000 μm long for the large ones and between 5–15 μm diameter and 50–100 μm length for the small ones. In tangential section, the spicules are circular, they have a simple structure, and no axial canal has been preserved. The large spicules are always monaxons, straight or slightly curved styles or strongyles. The spicules most closely resemble halichondrid/axinellid demosponge spicules and are important rare evidence of the existence of spicules in Palaeozoic stromatoporoids, reinforcing the interpretation that stromatoporoids were sponges. The basal skeleton may have had an aragonitic spherulitic mineralogy. Furthermore, the spicules indicate that this stromatoporoid sample is a demosponge.     

A Type IV Translocated Legionella Cysteine Phytase Counteracts Intracellular Growth Restriction by Phytate

The causative agent of Legionnaires'' pneumonia, Legionella pneumophila, colonizes diverse environmental niches, including biofilms, plant material, and protozoa. In these habitats, myo-inositol hexakisphosphate (phytate) is prevalent and used as a phosphate storage compound or as a siderophore. L. pneumophila replicates in protozoa and mammalian phagocytes within a unique “Legionella-containing vacuole.” The bacteria govern host cell interactions through the Icm/Dot type IV secretion system (T4SS) and ∼300 different “effector” proteins. Here we characterize a hitherto unrecognized Icm/Dot substrate, LppA, as a phytate phosphatase (phytase). Phytase activity of recombinant LppA required catalytically essential cysteine (Cys²³¹) and arginine (Arg²³⁷) residues. The structure of LppA at 1.4 Å resolution revealed a mainly α-helical globular protein stabilized by four antiparallel β-sheets that binds two phosphate moieties. The phosphates localize to a P-loop active site characteristic of dual specificity phosphatases or to a non-catalytic site, respectively. Phytate reversibly abolished growth of L. pneumophila in broth, and growth inhibition was relieved by overproduction of LppA or by metal ion titration. L. pneumophila lacking lppA replicated less efficiently in phytate-loaded Acanthamoeba castellanii or Dictyostelium discoideum, and the intracellular growth defect was complemented by the phytase gene. These findings identify the chelator phytate as an intracellular bacteriostatic component of cell-autonomous host immunity and reveal a T4SS-translocated L. pneumophila phytase that counteracts intracellular bacterial growth restriction by phytate. Thus, bacterial phytases might represent therapeutic targets to combat intracellular pathogens.     

Oncofetal H19 RNA promotes tumor metastasis

The oncofetal H19 gene transcribes a long non-coding RNA(lncRNA) that is essential for tumor growth. Here we found that numerous established inducers of epithelial to mesenchymal transition(EMT) also induced H19/miR-675 expression. Both TGF-β and hypoxia concomitantly induced H19 and miR-675 with the induction of EMT markers. We identified the PI3K/AKT pathway mediating the inductions of Slug, H19 RNA and miR-675 in response to TGF-β treatment, while Slug induction depended on H19 RNA. In the EMT induced multidrug resistance model, H19 level was also induced. In a mouse breast cancer model, H19 expression was tightly correlated with metastatic potential. In patients, we detected high H19 expression in all common metastatic sites tested, regardless of tumor primary origin. H19 RNA suppressed the expression of E-cadherin protein. H19 up-regulated Slug expression concomitant with the suppression of E-cadherin protein through a mechanism that involved miR-675. Slug also up-regulated H19 expression and activated its promoter. Altogether, these results may support the existence of a positive feedback loop between Slug and H19/miR-675, that regulates E-cadherin expression. H19 RNA enhanced the invasive potential of cancer cells in vitro and enhanced tumor metastasis in vivo. Additionally, H19 knockdown attenuated the scattering and tumorigenic effects of HGF/SF. Our results present novel mechanistic insights into a critical role for H19 RNA in tumor progression and indicate a previously unknown link between H19/miR-675, Slug and E-cadherin in the regulation of cancer cell EMT programs.     

Lengthening of the duration of xylogenesis engenders disproportionate increases in xylem production

In cold climates, the expected global warming will lead to earlier cambial resumptions in spring, with a resultant lengthening of the growing season but unknown consequences on forest productivity. The phenological traits of cambium activity and xylem formation were analyzed at a short time scale along a thermal gradient represented by an alti‐latitudinal range from the 48th to 53rd parallels and covering the whole closed black‐spruce [Picea mariana (Mill.) BSP] forest in Quebec, Canada. A hypothesis was tested that warmer temperatures influence cambium phenology, allowing longer duration and higher intensity of growth, and resulting in proportionally increased xylem production. From April to October 2012, cell division in cambium and post‐cambial differentiation of xylem were observed on anatomical sections obtained from microcores collected weekly from the stem of fifty trees. The southern and warmer site was characterized by the highest radial growth, which corresponded to both the highest rates and longest durations of cell production. The differences in terms of xylem phenology and growth were marginal between the other sites. Xylem growth was positively correlated with rate and duration of cell production, with the latter explaining most variability in growth. Within the range analyzed, the relationship between temperature and most phenological phases of xylogenesis was linear. On the contrary, temperature was related with cell production according to an exponential pattern. Periods of xylogenesis of 14 days longer (+13.1%) corresponded to a massive increase in cell production (33 cells, +109%). This disproportionate change occurred at a May–September average temperature of ca. 14 °C and a snow‐free period of 210–235 days. At the lower boundary of the distribution of black spruce, small environmental changes allowing marginal lengthening of the period of cell division could potentially lead to disproportionate increases in xylem cell production, with substantial consequences for the productivity of this boreal species.     

Gestational diabetes mellitus modulates neonatal high-density lipoprotein composition and its functional heterogeneity

Gestational diabetes mellitus (GDM) is related to neonatal macrosomia and an increased risk of vascular events. We hypothesized that GDM exerts qualitative effects on neonatal high-density lipoprotein (HDL). HDL was isolated from control (n = 11) and GDM maternal/neonatal donors (n = 9) and subjected to shotgun proteomics. Differences in HDL mobility were assessed by FPLC and native gel-electrophoresis. Paraoxonase (PON1) activity, cholesterol ester-transfer protein (CETP) mass and activity, phospholipid, triglyceride and cholesterol concentrations were quantified with commercial kits. Total anti-oxidative capacity and cholesterol efflux capability of HDLs were measured. Four proteins involved in lipid metabolism, inflammation and innate immunity were differentially expressed between controls and GDM neonates. ApoM (decreased, p < 0.05) and SAA1 (increased, p < 0.05) showed the same differences on both, maternal and neonatal GDM HDL. Lower PON1 protein expression was corroborated by lower activity (p < 0.05) which in turn was associated with attenuated anti-oxidant capacity of GDM HDL. Protein changes were accompanied by increased levels of triglycerides and decreased levels of cholesterol esters, respectively. The observed differences in GDM HDL lipid moiety may be related to CETP mass and activity alterations. The rate of cholesterol efflux from term trophoblasts to maternal and from placental endothelial cells to neonatal GDM HDL was impaired (p < 0.05). In conclusion, GDM causes changes in HDL composition and is intimately associated with impaired cholesterol efflux capability as well as diminished anti-oxidative particle properties. Remodeling of neonatal GDM HDL in utero supports the hypothesis that maternal conditions in pregnancy impact neonatal lipoprotein metabolism.