The stele – a developmental perspective on the diversity and evolution of primary vascular architecture

The stele concept is one of the oldest enduring concepts in plant biology. Here, I review the history of the concept and build an argument for an updated view of steles and their evolution. Studies of stelar organization have generated a widely ranging array of definitions that determine the way we classify steles and construct scenarios about the evolution of stelar architecture. Because at the organismal level biological evolution proceeds by changes in development, concepts of structure need to be grounded in development to be relevant in an evolutionary perspective. For the stele, most traditional definitions that incorporate development have viewed it as the totality of tissues that either originate from procambium – currently the prevailing view – or are bordered by a boundary layer (e.g. endodermis). Consensus between these two perspectives can be reached by recasting the stele as a structural entity of dual nature. Following a brief review of the history of the stele concept, basic terminology related to stelar organization, and traditional classifications of the steles, I revisit boundary layers from the perspective of histogenesis as a dynamic mosaic of developmental domains. I review anatomical and molecular data to explore and reaffirm the importance of boundary layers for stelar organization. Drawing on information from comparative anatomy, developmental regulation, and the fossil record, I propose a stele concept that integrates both the boundary layer and the procambial perspectives, consistent with a dual nature of the stele. This dual stele model posits that stelar architecture is determined at the apical meristem by two major cell fate specification events: a first one that specifies a provascular domain and its boundaries, and a second event that specifies a procambial domain (which will mature into conducting tissues) from cell subpopulations of the provascular domain. If the position and extent of the developmental domains defined by the two events are determined by different concentrations of the same morphogen (most likely auxin), then the distribution of this organizer factor in the shoot apical meristem, as modulated by changes in axis size and the effect of lateral organs, can explain the different stelar configurations documented among tracheophytes. This model provides working hypotheses that incorporate assumptions and generate implications that can be tested empirically. The model also offers criteria for an updated classification of steles in line with current understanding of plant development. In this classification, steles fall into two major categories determined by the configuration of boundary layers: boundary protosteles and boundary siphonosteles, each with subtypes defined by the architecture of the vascular tissues. Validation of the dual stele model and, more generally, in-depth understanding of the regulation of stelar architecture, will necessitate targeted efforts in two areas: (i) the regulation of procambium, vascular tissue, and boundary layer specification in all extant vascular plants, considering that most of the diversity in stelar architecture is hosted by seed-free plants, which are the least explored in terms of developmental regulation; (ii) the configuration of vascular tissues and, especially, boundary layers, in as many extinct lineages as possible.     

Characterization of ligno-cellulosic materials bleached with oxo-diperoxo-molybdates

A newly effective system was used to bleach ligno-cellulosic textile materials. This system is based on two different newly synthesized natrium oxo-diperoxo molybdates, Na₂[MoO (O₂)₂(C₂O₄)] and Na₂[MoO (O₂)₂(C₆H₆O₇)].     

Cross-linked amylose as matrix for drug controlled release. X-ray and FT-IR structural analysis

For cross-linked amylose (CLA) tablets prepared by direct compression, a linear increase in cross-linking degree (cld) defined as percentage of epichlorohydrin cross-linker/polymer, generates non-monotonous variation of drug release time. Controlled release (up to 20–24 h) properties were obtained only for tablets from CLA (Contramid^TM) with relatively low cld (CLA-2 up to CLA-6). Moderate increase in cld (CLA-15) generates a sharp decrease in the release time (2–6 h). This is a particular characteristic of the CLA matrix. The controlled release properties were related to the X-ray pattern of the dry CLA network. The increase in cld induces a transition from B-type (double helix) to a predominat V-type (single helix) and to more amorphous conformation of CLA powders. Furthermore, FT-IR data indicated low free water content at low cld. For low cross-linked CLA, chains are closely located and stabilized by HO groups involved in hydrogen bonding and thus more resistant to hydration and more appropriate for the control of drug release.     

Experimental Studies on the Formation of Volatile Nitrogen Compounds Induced by Pseudomonas Fragi in A Synthetic Medium with Amino Acids as Source of Nitrogen

The influence of the growth of Pseudomonas fragi strain F 111 was studied in a synthetic medium. It was shown that volatile nitrogen compounds were rapidly liberated as a result of the decomposition at 5°C of arginine and histidine. A later and slower increase of TVN was observed in media, which contained lysine or urea. From the other 7 amino acids which were included in the test, no increase of TVN was observed to be caused by the strain F 11. It was shown that within the range of 0.05 to 0.8 % histidine added to the basic salt solution the amount of TVN liberated was correlated to the amount of histidine included in the media. At the TVN maximum approx. 50 % of the amino acid nitrogen of the medium was recovered as TVN. It was further shown that the liberation of TVN was correlated to the added amount of arginine and histidine included in the growth medium. The presence of lysine also influenced on the TVN maximum which was reached. In the synthetic medium to which arginine or histidine was added the growth of strain F 111 was stimulated by the presence of glucose. The acids produced by the oxidative breakdown of glucose were neutralized partly by the volatile bases produced in the decomposition of amino acids. The ability of the Pseudomonas fragi to grow in anaerobic conditions and to produce enzymes which could decompose histidine was studied. It was concluded that the anaerobic breakdown of histidine was similar to the anaerobic breakdown of arginine reported by other authors.     

Early Prediction of Sepsis Incidence in Critically Ill Patients Using Specific Genetic Polymorphisms

Several diagnostic methods for the evaluation and monitoring were used to find out the pro-inflammatory status, as well as incidence of sepsis in critically ill patients. One such recent method is based on investigating the genetic polymorphisms and determining the molecular and genetic links between them, as well as other sepsis-associated pathophysiologies. Identification of genetic polymorphisms in critical patients with sepsis can become a revolutionary method for evaluating and monitoring these patients. Similarly, the complications, as well as the high costs associated with the management of patients with sepsis, can be significantly reduced by early initiation of intensive care.     

Effect of energy deprivation on metabolite release by anaerobic marine naphthalene-degrading sulfate-reducing bacteria

The aromatic hydrocarbon naphthalene, which occurs in coal and oil, can be degraded by aerobic or anaerobic microorganisms. A wide-spread electron acceptor for the latter is sulfate. Evidence for in situ naphthalene degradation stems in particular from the detection of 2-naphthoate and [5,6,7,8]-tetrahydro-2-naphthoate in oil field samples. Because such intermediates are usually not detected in laboratory cultures with high sulfate concentrations, one may suppose that conditions in reservoirs, such as sulfate limitation, trigger metabolite release. Indeed, if naphthalene-grown cells of marine sulfate-reducing Deltaproteobacteria (strains NaphS2, NaphS3 and NaphS6) were transferred to sulfate-free medium, they released 2-naphthoate and [5,6,7,8]-tetrahydro-2-naphthoate while still consuming naphthalene. With 2-naphthoate as initial substrate, cells produced [5,6,7,8]-tetrahydro-2-naphthoate and the hydrocarbon, naphthalene, indicating reversibility of the initial naphthalene-metabolizing reaction. The reactions in the absence of sulfate were not coupled to observable growth. Excretion of naphthalene-derived metabolites was also achieved in sulfate-rich medium upon addition of the protonophore carbonyl cyanide4-(trifluoromethoxy)phenylhydrazone or the ATPase inhibitor N,N′-dicyclohexylcarbodiimide. In conclusion, obstruction of electron flow and energy gain by sulfate limitation offers an explanation for the occurrence of naphthalene-derived metabolites in oil reservoirs, and provides a simple experimental tool for gaining insights into the anaerobic naphthalene oxidation pathway from an energetic perspective.     

The Use of Exosomes as Biomarkers for Evaluating and Monitoring Critically Ill Polytrauma Patients with Sepsis

Regarding genetic biomarkers for early assessment and monitoring the clinical course in polytrauma patients with sepsis, in recent years a remarkable evolution has been highlighted. One of the main representatives is the exosome miRNAs. In this paper, we would like to present in more details the various methods of using exosome miRNAs as a biomarker for monitoring polytrauma patients with sepsis, as well as establishing a belated outcome by aggregating the entire clinical aspects. The use of exosome miRNAs for late evaluating and monitoring the clinical evolution of polytrauma patients can bring significant improvements in current clinical practice through the optimization and modulation of intensive care according to the needs of each patient individually.