Chlorophyll fluorescence induction and relaxation system for the continuous monitoring of photosynthetic capacity in photobioreactors

The development of high‐performance photobioreactors equipped with automatic systems for non‐invasive real‐time monitoring of cultivation conditions and photosynthetic parameters is a challenge in algae biotechnology. Therefore, we developed a chlorophyll (Chl) fluorescence measuring system for the online recording of the light‐induced fluorescence rise and the dark relaxation of the flash‐induced fluorescence yield (Qa^? ? re‐oxidation kinetics) in photobioreactors. This system provides automatic measurements in a broad range of Chl concentrations at high frequency of gas‐tight sampling, and advanced data analysis. The performance of this new technique was tested on the green microalgae Chlamydomonas reinhardtii subjected to a sulfur deficiency stress and to long‐term dark anaerobic conditions. More than thousand fluorescence kinetic curves were recorded and analyzed during aerobic and anaerobic stages of incubation. Lifetime and amplitude values of kinetic components were determined, and their dynamics plotted on heatmaps. Out of these data, stress‐sensitive kinetic parameters were specified. This implemented apparatus can therefore be useful for the continuous real‐time monitoring of algal photosynthesis in photobioreactors.     

Hair Mineral and Trace Element Content in Children with Down’s Syndrome

Biological Trace Element Research - Chronic exposure to lead causes disruption to energy production mechanisms and tissue damage, in particular through its binding to thiol groups and competition...     

Structural variability of DNA-containing Mg-pyrophosphate microparticles: optimized conditions to produce particles with desired size and morphology

Our previous studies demonstrated the formation of structurally diverse DNA-containing microparticles (DNA MPs) in PCR with Mg-pyrophosphate (MgPPi) as the structure-forming component. These DNA MPs were referred to major structural types: microdisks (2D MPs) with nanometer thickness and 3D MPs with sophisticated morphology and constructed from intersecting disks and their segments. Little is known about factors that influence both the morphology and size of DNA MPs, and the present study was aimed at fulfilling this gap. We showed that the addition of Mn²⁺ cations to PCR mixtures caused the profound changes in MPs morphology, depending on DNA polymerase used (KlenTaq or Taq). Asymmetric PCR with 20-fold decrease in the concentration of one of two primers facilitated the predominant formation of microdisks with unusual structure. The addition of 1 mM Na-pyrophosphate to PCR mixtures with synthesized DNA and subsequent thermal cycling (10–15 cycles) were optimal to produce microdisks or nanometer 3D particles. Using electron microscopy, we studied also the structure of inorganic micro- and nanoparticles from MgPPi, formed during multiple heating and cooling cycles of a mixture of Mg²⁺ and Na-pyrophosphate in various regimes. Also, we found the conditions to yield planar (Mg·Mn)PPi nanocrystals (diameter ~100 nm and thickness ~10 nm) which efficiently adsorbed exogenous DNA. These inorganic nanoparticles are promising for DNA delivery in transfection studies. Mechanisms to be involved in structural modifications of MPs and perspectives of their practical application are discussed.     

Correction to: Correlative Inhibition Between Branches in Two-Branched Pea Seedlings is Cultivar-Dependent

Journal of Plant Growth Regulation - The original version of this article unfortunately contained a mistake in Fig. 5. The dot lines are missing and some unnecessary circles are filled in...     

Novel protein from larval sponge cells,ilborin, is related to energy turnover and calcium binding and is conserved among marine invertebrates

Sponges (phylum Porifera) are early-branching animals, whose outwardly simple body plan is underlain by a complex genetic repertoire. The transition from a mobile larva to an attached filter-feeding organism occurs by metamorphosis, a process accompanied by a radical change of the body plan and cell transdifferentiation. The continuity between larval cells and adult tissues is still obscure. In a previous study, we have produced polyclonal antibodies against the major protein of the flagellated cells covering the larva of the sponge Halisarca dujardini, used them to trace the fate of these cells and shown that the larval flagellated cells transdifferentiate into the choanocytes. In the present work, we identified the sequence of this novel protein, which we named ilborin. A search in the open databases showed that multiple orthologues of the newly identified protein are present in sponges, cnidarians, flatworms, ctenophores and echinoderms, but none of them has been described yet. Ilborin has two conserved domains: triosephosphate isomerase-barrel, which has enzymatic activity against macroergic compounds, and canonical EF-hand, which binds calcium. mRNA of ilborin is expressed in the larval flagellated cells. We suggest that the new protein is involved in the calcium-mediated regulation of energy metabolism, whose activation precedes metamorphosis.     

VEGF receptor 2/‐3 heterodimers detected in situ by proximity ligation on angiogenic sprouts

The vascular endothelial growth factors VEGFA and VEGFC are crucial regulators of vascular development. They exert their effects by dimerization and activation of the cognate receptors VEGFR2 and VEGFR3. Here, we have used in situ proximity ligation to detect receptor complexes in intact endothelial cells. We show that both VEGFA and VEGFC potently induce formation of VEGFR2/‐3 heterodimers. Receptor heterodimers were found in both developing blood vessels and immature lymphatic structures in embryoid bodies. We present evidence that heterodimers frequently localize to tip cell filopodia. Interestingly, in the presence of VEGFC, heterodimers were enriched in the leading tip cells as compared with trailing stalk cells of growing sprouts. Neutralization of VEGFR3 to prevent heterodimer formation in response to VEGFA decreased the extent of angiogenic sprouting. We conclude that VEGFR2/‐3 heterodimers on angiogenic sprouts induced by VEGFA or VEGFC may serve to positively regulate angiogenic sprouting.     

Redox-sensitive mechanism of no scavenging by nitronyl nitroxides

Nitronyl nitroxides, NN., have been increasingly used in the field of NO-related studies as specific antagonists of NO. . We employed a combination of EPR and NMR spin trapping to study the mechanisms of the reaction of NN. with NO. in reducing environments. EPR allowed observation of NO-induced transformation of the paramagnetic trap, NN., to the corresponding iminonitroxide, IN. . In a complementary way, corresponding EPR-invisible diamagnetic products (the hydroxylamines NN-H and IN-H) were detected by 19F-NMR using newly synthesized fluorinated traps. Addition of reducing agents to a solution of NN. resulted in fast disappearance of its EPR spectra and appearance of a 19F-NMR peak of the corresponding hydroxylamine, NN-H. Addition of NO. as a bolus, or NO. generated on sodium nitroprusside photolysis, resulted in 19F-NMR-detectable accumulation of the hydroxylamine, IN-H. Upon high rates of NO. generation in ascorbate-containing solutions, partial recovery of NN. was observed, which undergoes further reactions with NO. and ascorbate in a competitive manner. Using 19F-NMR and a fluorinated trap, NO-induced conversion of NN-H into IN-H was also observed in vivo in hypertensive ISIAH rats compared with normotensive WAG rats. The results provide insight into a new potential redox-sensitive mechanism of the antagonistic action of NN. against NO., which may provide insight into previously unexplained behavior of this category of NO-reacting compounds.